Inter-satellite load balancing routing method and system based on topology switching for polar orbit constellation

Abstract

The application discloses a kind of based on topological switching's polar-orbit constellation inter-satellite load balancing routing method and system, first ground station is according to satellite constellation characteristics and carries out ground block division, is combined with reverse seam longitude information and satellite inter-satellite interconnect relationship, obtains ground block interconnect relationship;According to the service intensity of ground block, combined with ground block interconnect relationship, the link load intensity between block is calculated, and ground block topology table is obtained;According to ground block topology table, for each block, calculate routing table;According to the boundary condition of ground block, combined with satellite operation law, the time of each satellite switching coverage block is calculated, and the topology table, routing table, block switching time calculated by ground are uploaded to satellite, each satellite is according to the latitude and longitude information of itself operation, combined with block switching time, select a routing table matched with current time from ground block routing table vector as the routing table currently used by this satellite, and data is transmitted according to the routing table.

Description

Technical Field

[0001] This invention relates to the field of wireless network communication technology, and in particular to a polar-orbit constellation inter-satellite load balancing routing method and system based on topology switching. Background Technology

[0002] With the rapid development of communication technology, satellite communication has become an important research trend in the field. Low Earth Orbit (LEO) satellite networks, due to their low deployment cost, wide coverage, and advantages such as low two-way latency, low satellite-to-ground link loss, and high data transmission rates when communicating with ground nodes, have become an indispensable part of modern communication, navigation, and remote sensing. However, due to the uneven distribution of ground user traffic and the complex spatial distribution and time-varying nature of satellite networks, LEO satellite networks, while meeting ever-increasing mission demands, also face problems such as uneven resource utilization and network congestion. Currently, LEO satellite network routing algorithms primarily rely on inter-satellite links for on-board routing planning. Because LEO satellites are constantly moving, the network must continuously detect satellite orbits and positions, mapping the user's geographical location to the satellite covering that user to predict which satellite will cover the destination user at a specific time. This process requires highly automated systems and complex algorithms to achieve efficient and reliable inter-satellite routing. Therefore, designing a reasonable load-balancing routing algorithm to improve the overall network resource utilization efficiency and reduce computational complexity is particularly important.

[0003] Chinese patent application CN202310449553.4, entitled "A Routing Method and System for Low-Earth Orbit Satellite Constellation Networks," discloses a routing method and system for low-Earth orbit satellite constellation networks. Its features include timely route updates based on real-time link status information to better respond to changes in satellite network topology and network traffic; and enhanced network load balancing by providing a wider range of route options. However, its drawbacks include: the need for real-time collection and analysis of large amounts of data may increase the computational and storage overhead of nodes, affecting communication performance. Furthermore, frequent calculation and updating of routing information will increase the energy consumption of nodes, impacting the long-term stability of the satellite network.

[0004] Chinese patent application CN202010009907.X, entitled "Method and System for Inter-Satellite Load Routing Balancing of Low-Earth Orbit Satellite Constellations," discloses a method and system for inter-satellite load routing balancing of low-Earth orbit satellite constellations. Its key feature is that the Earth's surface is divided into multiple coverage areas based on the constellation configuration of the low-Earth orbit satellites. A traffic model is established to obtain the potential congestion values ​​for multiple coverage areas, and inter-satellite load routing is performed regionally based on these potential congestion values. However, its shortcomings are: when dividing the ground into regions, the regions are obtained by evenly dividing the Earth's latitude and longitude based on the number of satellite orbits and the number of satellites on each orbital plane, without fully considering the mapping relationship between ground areas and satellites, leading to significant errors in calculating potential congestion values. Furthermore, the method of routing by informing neighboring nodes to reduce transmission rates and querying the congestion status of next-hop nodes increases communication latency.

[0005] Therefore, combining ground traffic distribution information with the actual characteristics of low-Earth orbit constellation networks, developing a routing strategy that can fully adapt to the actual application environment, cope with congestion, and improve the resource utilization efficiency of the entire network has become a problem that needs to be solved in the research of load balancing routing strategies for low-Earth orbit satellite networks. Summary of the Invention

[0006] The purpose of this invention is to provide a load balancing routing method and system for polar-orbiting constellations based on topology switching, in order to solve the problems of existing low-orbit satellite constellation load balancing routing algorithms not fully considering ground traffic distribution information, not matching the actual operation patterns of satellites, and having high computational overhead.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The polar constellation inter-satellite load balancing routing method based on topology switching includes the following steps: Step S10: The ground control center divides the ground into blocks according to the satellite constellation parameters, calculates the boundary conditions of the ground blocks, and obtains the set of ground blocks; Step S20: Based on the set of ground blocks, combined with the longitude information of the reverse seam and the inter-satellite connectivity, calculate the ground block connectivity matrix; Step S30: Based on the service intensity of each ground block and the ground block connectivity matrix, calculate the inter-block link load intensity and generate a ground block topology vector. Step S40: Calculate the routing table for each ground block based on the ground block topology map vector, and generate the ground block routing table vector; Step S50: Based on the boundary conditions of the ground block and the satellite operation rules, calculate the time for each satellite to switch coverage blocks. The time for satellites to switch coverage blocks is referred to as the block switching time. Step S60: Upload the calculated ground block topology vector, ground block routing table vector, and block switching time to the landing satellite, and then spread them to other satellite nodes in the entire network from the landing satellite; Step S70: Each satellite selects a routing table that matches the current time from the ground block routing table vector based on its own latitude and longitude information and the block switching time, and uses the routing table to transmit data.

[0008] Furthermore, in step S10, the ground control center divides the ground into blocks based on the satellite constellation parameters, calculates the boundary conditions of the ground blocks, and obtains the set of ground blocks using the following specific method: Based on satellite constellation type, the ground is divided into latitude and longitude regions. The set of ground blocks is denoted as _block_, where each block corresponds to a satellite covering that block. ,in, The coverage of the i-th orbital plane satellite in the initial state There are 1 block, and the size of each block is 1. ; in, It is the total number of satellites in the constellation. It refers to the number of orbital planes of a constellation. It refers to the number of satellites in each orbital plane. The latitude range corresponding to the coverage area. The longitude range corresponding to the coverage area, and The sizes are respectively:

[0009] remember For blocks The latitude of the center For blocks The longitude of the center is taken as follows: , .

[0010] Depend on ,in Let F be the phase difference between adjacent orbital satellites, and F be the phase factor, then:

[0011]

[0012]

[0013]

[0014] remember , , , Blocks Given the positions of the four vertices, then: =

[0015] =

[0016] =

[0017] =

[0018] =

[0019] =

[0020] =

[0021] = .

[0022] Furthermore, the specific method for calculating the ground block connectivity matrix in step S20 based on the ground block set, combined with the reverse seam longitude information and satellite inter-satellite connectivity, is as follows: Step S21: Determine the connectivity status between blocks. When the ascent orbit of the first orbital plane satellite is located at longitude 0°~ In the case of satellite reverse seams, the communication links between adjacent ground blocks are considered broken, and the connectivity is represented by ∞; except for the adjacent ground blocks corresponding to satellite reverse seams, the communication between other adjacent blocks corresponds to the inter-satellite links of the satellites covering that block, and the connectivity is represented by 1; non-adjacent blocks cannot communicate directly and are considered broken, and the connectivity is represented by ∞; communication within a block is represented by 0; thus, the ground block connectivity matrix is ​​obtained. ; Among them, elements Represents a block and blocks The connection between them It is the total number of blocks; Step S22, according to step S21, as the Earth rotates, when the ascending orbit of the first orbital plane satellite is located at longitude 0°- Between ~0°, the communication link between adjacent ground blocks corresponding to the satellite reverse seam is considered broken, and the connectivity is represented by ∞; except for the adjacent ground blocks corresponding to the satellite reverse seam, the communication between other adjacent blocks corresponds to the inter-satellite link of the satellite covering that block, and the connectivity is represented by 1; non-adjacent blocks cannot communicate directly and are considered broken, and the connectivity is represented by ∞; communication within a block is represented by 0; thus, the ground block connectivity matrix is ​​obtained. ; Step S23, and so on, the ascending orbit of the first orbital plane satellite moves in longitude by 100 degrees. The satellite reverse slit reaches a new block, obtaining a new connectivity matrix, until the satellite reverse slit returns to its initial position, completing one Earth rotation period T, and thus obtaining... Let there be a set of connectivity relations. ,in, Let be the i-th connectivity matrix.

[0023] Furthermore, the specific method for generating the ground block topology map vector in step S30 is as follows: Based on the number of internet users in each block, the potential satellite network traffic for each block is obtained. This leads to the set of connectivity relationships. The corresponding inter-block link load strength set ={ },in, Represents the connectivity matrix The corresponding link load strength matrix; Among them, elements For blocks and blocks Link load strength between them, when At that time, the corresponding ,when Or when At that time, the corresponding = ; in, , Blocks and blocks Potential traffic For blocks and blocks The distance between centers; Among them, blocks and blocks Distance between centers The calculation method is as follows:

[0024] in, and Representing blocks and blocks The latitude of the center point and Representing blocks and blocks Longitude of the center point Represents the radius of the Earth; Using blocks as nodes and inter-block link load strength as edges, generate a set of connectivity relationships. Corresponding topological graph vector ;in, Represents the connectivity matrix The corresponding topology table consists of a block set. Inter-block link load strength matrix composition.

[0025] Further, in step S40, a routing table is calculated for each ground block to generate a ground block routing table vector. Specifically, the method involves using the inter-block link load strength as the weight and employing a minimum cost algorithm to calculate the routing table vector corresponding to the topology graph. Corresponding routing table vector For each path calculated, the weight of that path is increased by 1; in, Representation and topology table corresponding Zhang's routing table, express Each block has its own routing table, and each routing table maintains the routes from the current block to all other blocks at the current time.

[0026] Furthermore, the specific method for calculating the switching time of each satellite's coverage block in step S50 is as follows: After the satellite is powered on, the topology map is activated. and routing table Corresponding to the satellite's initial position, after the satellite arrives at the new block, a block handover is performed. The block handover time is calculated based on the latitudinal range of the ground block and the satellite's speed. = ; in, For the satellite's angular velocity, For the Earth's radius, For the orbital height, For gravitational constant, Earth mass; When the satellite reverse slot corresponds to a new block, a topology table switch and a routing table switch are performed. The switch times are calculated based on the longitude range spanned by the ground block and the Earth's rotation speed. = ,in, This refers to the Earth's rotation speed; After each topology switch, a phase deviation occurs between the satellite and the latitude of the corresponding coverage block after the topology switch. The phase deviation compensation time is calculated based on the phase deviation of the block latitude and the satellite's motion velocity. ;in, This represents the phase difference between satellites in adjacent orbits.

[0027] Furthermore, in step S60, the calculated ground block topology vector, ground block routing table vector, and block switching time are uploaded to the landing satellite, and then disseminated from the landing satellite to other satellite nodes in the entire network. The specific method is as follows: After the satellite is powered on, the ground station establishes a connection with the satellite covering the ground station. At this time, the satellite's identity changes to a landing satellite. The ground station uploads information packets consisting of the calculated ground block topology table, ground block routing table, and block switching time to the landing satellite, which then disseminates the information packets to other satellites in the network.

[0028] Furthermore, in step S70, each satellite, based on its own latitude and longitude information and the block switching time, selects a routing table from the ground block routing table vector that matches the current time as the routing table currently used by that satellite, and transmits data according to this routing table. The specific method is as follows: Each block has Zhang's routing table, corresponding to Each connection relationship is maintained in its routing table, which maintains the routes from the current block to all other blocks under that connection relationship. When a satellite enters the block, it undertakes the service requirements of that block. Based on its own latitude and longitude information and the block switching time, it determines the current ground block connectivity and selects the routing table that matches the current time from the ground block routing table vector as the routing table currently used by the satellite. Based on the routing table currently used by the block, it finds the transmission path from the source node to the destination node. ; in, Indicates the source node of the ground block. The node representing the destination of the ground block. Indicates the communication nodes in the transmission path; The satellite selects a satellite that covers a block of the transmission path at the current time to transmit the data, based on the transmission path. When a satellite leaves the block, a subsequent satellite takes over the services of that block and performs a link switch.

[0029] The polar-orbit constellation inter-satellite load balancing routing system based on topology switching includes a ground control center module and a satellite service transmission module; wherein: The ground control center module is used to divide ground blocks according to satellite constellation parameters, and obtain a ground block connectivity matrix by combining reverse seam longitude information and inter-satellite connectivity relationships; based on the service intensity of ground blocks and the ground block connectivity matrix, it calculates the inter-block link load intensity and obtains a ground block topology table; based on the ground block topology table, it calculates a routing table for each block; based on the ground block boundary conditions and satellite operation patterns, it calculates the timing pattern of each satellite switching coverage blocks; and it uploads the calculated topology table, routing table, block switching time, and other information to the satellites. The satellite service transmission module is used to select a routing table that matches the current time from the ground block routing table vector based on its own latitude and longitude information and the block switching time, and then transmit data according to the routing table.

[0030] Furthermore, the ground control center module includes: The block partitioning module is used to divide the ground into blocks, calculate the boundary conditions of the ground blocks, and obtain a set of ground blocks. The specific method is as follows: Based on satellite constellation type, the ground is divided into latitude and longitude regions. The set of ground blocks is denoted as _block_, where each block corresponds to a satellite covering that block. ,in, The coverage of the i-th orbital plane satellite in the initial state There are 1 block, and the size of each block is 1. ; in, It is the total number of satellites in the constellation. It refers to the number of orbital planes of a constellation. It refers to the number of satellites in each orbital plane. The latitude range corresponding to the coverage area. The longitude range corresponding to the coverage area, and The sizes are respectively:

[0031] remember For blocks The latitude of the center For blocks The longitude of the center is taken as follows: , ; Depend on ,in Let F be the phase difference between adjacent orbital satellites, and F be the phase factor.

[0032]

[0033]

[0034]

[0035] remember , , , Blocks The positions of the four vertices, then =

[0036] =

[0037] =

[0038] =

[0039] =

[0040] =

[0041] =

[0042] =

[0043] The connectivity matrix acquisition module is used to calculate the ground block connectivity matrix based on the ground block set, combined with the reverse seam longitude information and satellite inter-satellite connectivity. The specific method is as follows: Step S21: Determine the connectivity status between blocks. When the ascent orbit of the first orbital plane satellite is located at... ~ In the case of satellite reverse seams, the communication links between adjacent ground blocks are considered broken, and the connectivity is represented by ∞; except for the adjacent ground blocks corresponding to satellite reverse seams, the communication between other adjacent blocks corresponds to the inter-satellite links of the satellites covering that block, and the connectivity is represented by 1; non-adjacent blocks cannot communicate directly and are considered broken, and the connectivity is represented by ∞; communication within a block is represented by 0; thus, the ground block connectivity matrix is ​​obtained. ; Among them, elements Represents a block and blocks The connection between them It represents the total number of blocks.

[0044] Step S22, according to step S21, as the Earth rotates, when the ascending orbit of the first orbital plane satellite is located at longitude... - Between ~0°, the communication link between adjacent ground blocks corresponding to the satellite reverse seam is considered broken, and the connectivity is represented by ∞; except for the adjacent ground blocks corresponding to the satellite reverse seam, the communication between other adjacent blocks corresponds to the inter-satellite link of the satellite covering that block, and the connectivity is represented by 1; non-adjacent blocks cannot communicate directly and are considered broken, and the connectivity is represented by ∞; communication within a block is represented by 0; thus, the ground block connectivity matrix is ​​obtained. ; Step S23, and so on, the ascending orbit of the first orbital plane satellite moves in longitude by 100 degrees. The satellite reverse slit reaches a new block, obtaining a new connectivity matrix, until the satellite reverse slit returns to its initial position, completing one Earth rotation period T, and thus obtaining... Let there be a set of connectivity relations. ,in, Let i be the i-th connectivity matrix; The ground block topology vector acquisition module is used to calculate the inter-block link load strength based on the service intensity of each ground block and the ground block connectivity matrix, and generate a ground block topology vector. The specific method is as follows: Based on the number of internet users in each block, the potential satellite network traffic for each block is obtained. This leads to the set of connectivity relationships. The corresponding inter-block link load strength set ={ }.in, Represents the connectivity matrix The corresponding link load strength matrix; Among them, elements For blocks and blocks Link load strength between them, when At that time, the corresponding ,when Or when At that time, the corresponding = ; in, , Blocks and blocks Potential traffic For blocks and blocks The distance between centers; Among them, blocks and blocks Distance between centers The calculation method is as follows:

[0045] in, and Representing blocks and blocks The latitude of the center point and Representing blocks and blocks Longitude of the center point Represents the radius of the Earth; Using blocks as nodes and inter-block link load strength as edges, generate a set of connectivity relationships. Corresponding topological graph vector ;in, Represents the connectivity matrix The corresponding topology table consists of a block set. Inter-block link load strength matrix composition; The ground block routing table vector acquisition module is used to calculate the routing table for each block based on the ground block topology map vector, and generate the ground block routing table vector. The specific method is as follows: Using inter-block link load strength as weights, and employing a minimum cost algorithm, the vectors in the topology graph are calculated. Corresponding routing table vector For each path calculated, the weight of that path is increased by 1; in, Representation and topology table corresponding Zhang's routing table, express Each block has one routing table, and each routing table maintains the routes from the current block to all other blocks at the current time. The satellite handover coverage block pattern acquisition module is used to calculate the handover time for each satellite coverage block based on ground block boundary conditions and satellite operational patterns. The specific method is as follows: After the satellite is powered on, the topology map is activated. and routing table This corresponds to the satellite's initial position. After the satellite arrives at a new block, a block handover is performed. The block handover time is calculated based on the latitudinal range of the ground block and the satellite's speed. = ; in, For the satellite's angular velocity, For the Earth's radius, For the orbital height, For gravitational constant, Earth mass; When the satellite reverse slot corresponds to a new block, a topology table switch and a routing table switch are performed. The switch times are calculated based on the longitude range spanned by the ground block and the Earth's rotation speed. = ,in, This refers to the Earth's rotation speed; After each topology switch, a phase deviation occurs between the satellite and the latitude of the corresponding coverage block after the topology switch. The phase deviation compensation time is calculated based on the phase deviation of the block latitude and the satellite's motion velocity. ,in, The phase difference between satellites in adjacent orbits; The ground station uploading module is used to upload calculated topology vectors, routing table vectors, block switching times, and other information to the landing satellite, which then disseminates this information to other satellite nodes across the network. The specific method is as follows: After the satellite is powered on, the ground station establishes a connection with the satellite covering the ground station. At this point, the satellite's identity changes to a ground satellite. The ground station compiles the calculated topology table, routing table, block switching time, and other information into information packets and uploads them to the ground satellite, which then disseminates these packets to other satellites in the network. The satellite service transmission module includes: The routing table selection module is used by the satellite to select a routing table from the ground block routing table vector that matches the current time, based on its own latitude and longitude information and the block switching time. The specific method is as follows: Each block has Zhang's routing table, corresponding to Each connection relationship is defined. Each routing table maintains the routes from this block to all other blocks under that connection relationship. When a satellite enters the block, it undertakes the service requirements of that block. Based on its own latitude and longitude information and the block switching time, it determines the current ground block connectivity and selects the routing table that matches the current time from the ground block routing table vector as the routing table currently used by the satellite. Based on the routing table currently used by the block, it finds the transmission path from the source node to the destination node. ; in, Indicates the source node of the ground block. The node representing the destination of the ground block. Indicates the communication nodes in the transmission path; The service transmission module is used by the satellite to select satellites that cover the current time block in the transmission path according to the transmission path, and transmit the data. When a satellite leaves the block, a subsequent satellite takes over the services in that block and performs a link switch. Compared with the prior art, the present invention has the following beneficial technical effects: I. Current routing algorithms for low-Earth orbit (LEO) satellite networks primarily rely on inter-satellite links for on-board route planning. Because LEO satellites are constantly moving, the network must continuously monitor their orbits and positions, mapping a user's geographic location to the satellite covering that user to predict which satellite will cover the destination user at a specific time. This process requires highly automated systems and complex algorithms. In the method described here, by dividing the ground into blocks and planning routing tables for each block, it is only necessary to know which ground block the destination user is in. Satellites then forward services towards the destination ground block to complete service transmission, significantly reducing computational complexity.

[0046] Second, traditional ground segmentation methods typically use latitude and longitude grids to divide the Earth's surface into equally spaced square or rectangular areas. However, these methods do not consider the phase deviation between adjacent orbital satellites, leading to inconsistencies between the actual coverage area of ​​the satellites and the segmented areas. In this invention, based on the Earth's actual shape and considering parameters such as the number of orbital planes in the satellite constellation, the number of satellites on each plane, and the orbital phase factor, the ground is divided into irregular segments. Each satellite corresponds one-to-one with the ground segment it covers, reducing errors caused by the mismatch between satellite positions and the positions of the covered segments during potential traffic prediction and route planning.

[0047] Third, due to the high-speed motion of satellites and the Earth's rotation, the satellite-to-ground communication relationship exhibits irregular changes, requiring recalculation of the routing table each time to complete communication. In the method of this invention, the ground is divided into a finite number of blocks. Combining the satellite's reverse seam position and satellite motion patterns, the actual satellite operation patterns are integrated with the changes in ground block topology to plan a finite number of routing tables corresponding to the ground block topology. This ensures that the topology does not undergo structural changes within the calculated time interval, achieving more accurate route selection.

[0048] Fourth, due to the differences in traffic distribution across different ground blocks, by analyzing the traffic proportion of each ground block, we can further predict the potential traffic demand and inter-block link load intensity of each ground block. By sacrificing inter-block link load intensity, we can plan a routing table that consistently matches the ground traffic volume, enabling more efficient allocation of communication load and thus improving satellite network performance and resource utilization efficiency.

[0049] 5. After the ground-based system completes the routing table calculation and block switching time calculation, it uploads the routing table and block switching time information to the satellite. Satellite nodes, based on their own latitude and longitude information and the block switching time, periodically select the routing table that matches the current time for switching. This avoids the need for real-time collection of large amounts of data and frequent calculations and updates to the routing table, reducing the computational and storage overhead of satellite nodes, minimizing unnecessary energy consumption, reducing on-board processing latency, and improving the overall network efficiency and stability. Attached Figure Description

[0050] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0051] Figure 1 This is a flowchart of an example of the present invention; Figure 2 This is a schematic diagram of block division in an example of the present invention; Figure 3 Figure 4 This is a schematic diagram illustrating the switching of block connectivity relationships in an example of the present invention; Figure 5 This is a schematic diagram of routing table switching in an example of the present invention; Figure 6 This diagram illustrates how topology switching causes the original path to pass through a reverse seam, triggering satellite switching and path updates. Detailed Implementation

[0052] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0053] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0054] Example: A polar-orbit constellation inter-satellite load balancing routing method based on topology switching, the technical idea of ​​which is as follows: First, ground blocks are divided according to the characteristics of the satellite constellation. By combining the reverse seam longitude information and the inter-satellite connectivity, the ground block connectivity is obtained. Based on the service intensity of the ground blocks and the ground block connectivity, the inter-block link load intensity is calculated, resulting in a ground block topology table. Based on the ground block topology table, a minimum cost algorithm is used to calculate the routing table for each block. Based on the ground block boundary conditions and the satellite operation patterns, the switching time for each satellite to cover a block is calculated.

[0055] Secondly, the ground station uploads the calculated topology table, routing table, block switching time and other information to the landing satellite, which then disseminates it to other satellite nodes in the network.

[0056] Finally, each satellite selects a routing table from the ground block routing table vector that matches the current time based on its own latitude and longitude information and the block switching time, and uses this routing table to transmit data.

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with embodiments. Figure 1 The present invention will be further described in detail below.

[0058] The low-Earth orbit (LEO) satellite network of this invention consists of 80 LEO satellites in 8 orbital planes, with 10 satellites distributed on each plane. Each satellite is evenly distributed in an orbit at an altitude of 1000 km and an inclination of 87.5°, with a phase factor of 4. Except for the satellites on either side of the anti-slot, which have only 3 inter-satellite links (1 inter-orbit link and 2 intra-orbit links), each of the remaining satellites has 4 inter-satellite links, including 2 inter-orbit links and 2 intra-orbit links.

[0059] Step S10: Divide the ground into blocks according to the satellite constellation parameters: Reference Figure 2 Based on satellite constellation parameters, the ground is divided into blocks, each spanning 36° of latitude and 22.5° of longitude. The table below shows the latitude and longitude of the center point of each block: Table 1. Latitude and longitude coordinates of the center point of each block

[0060] Step S20: Based on the set of ground blocks, combined with the longitude information of the reverse seam and the inter-satellite connectivity, calculate the ground block connectivity matrix: Reference Figure 3 This represents the initial connectivity between blocks. The 80 blocks are virtualized as 80 points, each corresponding to a satellite. Inter-satellite links correspond to inter-block communication links. When the ascent orbit of the first orbital plane satellite is between 0° and 22.5° longitude (i.e., between blocks corresponding to the first and eighth orbital planes in the initial state), the communication link between adjacent blocks corresponding to the first and eighth orbital planes is considered broken, and the connectivity is represented by ∞. Except for satellite backslots corresponding to adjacent ground blocks, the communication link between other adjacent blocks corresponds to the inter-satellite link of the satellite covering that block, and the connectivity is represented by 1. Non-adjacent blocks cannot communicate directly and are considered broken, with the connectivity represented by ∞. Intra-block communication is represented by 0. The resulting connectivity matrix is: .

[0061]

[0062] As the Earth rotates, the ground region corresponding to the satellite's retrograde seam changes. (See reference...) Figure 4 At this point, the ascent orbit of the first orbital plane satellite is located between longitude -22.5° and 0°, meaning its ascent orbit lies between the blocks corresponding to the 8th and 7th orbital planes in the initial state. Therefore, the communication link between the blocks corresponding to the 8th and 7th orbital plane satellites in the initial state is considered broken, resulting in a connectivity matrix. .

[0063]

[0064] For the first orbital plane satellite, every 22.5° of longitude travel in its ascending orbit, the satellite's reverse slot reaches a new block, establishing a new connection, until the satellite's reverse slot returns to its initial position. The following pattern can be summarized: (1) The longitude position of the satellite orbit changes every time This means that for every 22.5° change in longitude of the satellite, the ground connectivity changes once.

[0065] (2) Within a connectivity relationship, the connectivity relationship of the blocks covered by satellites moving from south to north is: due south, due north, southwest, northeast; the connectivity relationship of the blocks covered by satellites moving from north to south is: due south, due north, northwest, southeast.

[0066] (3) The connectivity of the blocks covered by the satellite moving from south to north in the first orbital plane is: due south, due north, northeast; the connectivity of the blocks covered by the satellite moving from north to south in the first orbital plane is: due south, due north, southeast; the connectivity of the blocks covered by the satellite moving from south to north in the eighth orbital plane is: due south, due north, southwest; the connectivity of the blocks covered by the satellite moving from north to south in the eighth orbital plane is: due south, due north, northwest.

[0067] (4) When the Earth rotates once, the ascending orbit of the first orbital plane satellite returns to its initial position, completing one period T, resulting in 16 possible connections. Based on the Earth's rotation period... ,in ,get .

[0068] Denote the set of connectivity relations ,in, Let be the i-th connectivity matrix.

[0069] Step S30: Based on the service intensity of each ground block and combined with the ground block connectivity vector, calculate the inter-block link load intensity and generate a ground block topology vector. From the formula Given R=6371km, the initial distance between the center points of adjacent blocks of satellites in the same orbital plane is 4000.99km. The initial distances between the center points of adjacent blocks of satellites in adjacent orbital planes, from the poles to the equator, are: 2001.5087km, 2454.132km, 3053.2078km, 3559.1324km, and 3841.7003km, respectively.

[0070] When the connected matrix middle or At that time, the corresponding inter-block link load strength = When the connected matrix middle At that time, the corresponding inter-block link load strength Substitute , , To obtain the connected matrix Corresponding inter-block link load strength matrix :

[0071] Similarly, by combining the ground block connectivity vectors, we can obtain the connectivity set. The corresponding inter-block link load strength set ={ }.in, For the connectivity matrix The corresponding link load strength matrix.

[0072] Using blocks as nodes and inter-block link load strength as edges, generate a set of connectivity relationships. Corresponding topology table set .in, Represents the connectivity matrix The corresponding topology table consists of a block set. Inter-block link load strength matrix composition.

[0073] S40, based on the ground block topology map vector, calculate the routing table for each block and generate the ground block routing table vector: Using inter-block link load strength as the weight, and employing a minimum cost algorithm, the topology table set is calculated. The corresponding set of routing tables .

[0074] in, Representation and topology table corresponding There are 10 routing tables, one for each block, and each routing table maintains the routes from the current block to all other blocks at the current time.

[0075] S50 calculates the time for each satellite to switch coverage blocks based on ground block boundary conditions and satellite operation patterns: After the satellite is powered on, the topology table is activated. As the satellite moves, the coverage area changes. When a satellite reaches a new coverage area, a switchover is performed. The switchover time for each satellite coverage area is... = .in, ,get 630s.

[0076] When a satellite reverse seam corresponds to a new block, a topology table switch and a routing table switch are performed. The topology table and routing table switch time is... = ,in, rad / s, ,get .

[0077] After each topology switch, a phase deviation occurs between the satellite and the latitude of the corresponding coverage block after the topology switch. The phase deviation compensation time is... ,in ,get .

[0078] S60 uploads ground-calculated topology tables, routing tables, block switching times, and other information to the ground-based satellite, which then disseminates this information to other satellite nodes across the network. After the satellite is powered on, the ground station establishes a connection with the satellite covering the ground station. At this point, the satellite's identity changes to a ground satellite. The ground station compiles the calculated topology table, routing table, block switching time, and other information into information packets and uploads them to the ground satellite, which then disseminates these packets to other satellites in the network.

[0079] S70: Each satellite, based on its own latitude and longitude information and the block switching time, selects a routing table from the ground block routing table vector that matches the current time as the routing table currently used by that satellite, and transmits data according to this routing table. Each block has Zhang's routing table, corresponding to Each routing table maintains the routes from this block to all other blocks under this connection.

[0080] When a physical satellite enters the block, it undertakes the service requirements of that block. Based on its own latitude and longitude information and the block switching time, it determines the current ground block connectivity and selects a routing table from the ground block routing table vector that matches the current time as the routing table currently used by the satellite. Based on the routing table currently used by the block, it finds the transmission path from the source node to the destination node. ;in, Indicates the source node of the ground block. The node representing the destination of the ground block. This represents the communication nodes in the transmission path. Based on the transmission path, the satellite selects satellites that currently cover the blocks within the path to transmit data.

[0081] When a satellite leaves the block, it automatically transfers relevant information such as routing tables and service requirements to subsequent physical satellites and performs link switching.

[0082] Reference Figure 5 ,exist At that moment, the satellite's ascent orbit containing the reverse slot was located between 0° and 22.5° longitude. Initially, the communication link between the blocks corresponding to the satellites on the first and eighth orbital planes was considered broken, and the topology table was activated. When block A18 generates traffic to block A56, satellite S18 is positioned above block A18 and uses the routing table of block A18. A query of the routing table reveals that the transmission path from block A18 to block A56 is: A18→A17→A16→A27→A37→A48→A47→A46→A56. The satellites covering blocks A18, A17, A16, A27, A37, A48, A47, A46, and A56 are S18, S17, S16, S26, S36, S46, S45, S44, and S54, respectively. The corresponding satellite service transmission path is: S18→S17→S16→S26→S36→S46→S45→S44→S54. At +630s, the satellite arrives at the new block and performs a block handover. The satellites covering blocks A18, A17, A16, A27, A37, A48, A47, A46, and A56 are S17, S16, S15, S25, S35, S45, S44, S43, and S53, respectively. Satellite S17 takes over the routing table of block A18 and continues to handle the service from block A18 to block A46. The corresponding satellite service transmission path is: S17→S16→S15→S25→S35→S45→S44→S43→S53, and a link handover is performed.

[0083] Reference Figure 6 ,exist + At any given moment, due to Earth's rotation, the ascending orbit containing the satellite's reverse slot is between -22.5° and 0°. Initially, the communication link between the blocks corresponding to the satellites on the 8th and 7th orbital planes is considered broken, and the topology table is activated. At this time, satellite S26 is above block A18, and satellite S26 uses the routing table of block A18. According to the routing table, the transmission path from block A18 to block A56 is: A18→A19→A10→A11→A12→A13→A3→A56. The satellites covering blocks A18, A19, A10, A11, A12, A13, A3, and A56 are S26, S27, S28, S29, S20, S21, S11, and S1, respectively. The corresponding satellite service transmission path is: S26→S27→S28→S29→S20→S21→S11→S1.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the invention, but these changes, modifications or equivalent substitutions are all within the scope of protection of the pending claims of the invention.

Claims

1. A polar-orbit constellation inter-satellite load balancing routing method based on topology switching, characterized in that, Includes the following steps: Step S10: The ground control center divides the ground into blocks based on the satellite constellation parameters, calculates the boundary conditions of the ground blocks, and obtains a set of ground blocks. The specific method is as follows: Based on satellite constellation type, the ground is divided into latitude and longitude regions. The set of ground blocks is denoted as _block_, where each block corresponds to a satellite covering that block. ,in, The coverage of the i-th orbital plane satellite in the initial state There are 10 blocks, each block being 100 blocks in size. ; in, It is the total number of satellites in the constellation. It refers to the number of orbital planes of a constellation. It refers to the number of satellites in each orbital plane. The latitude range corresponding to the coverage area. The longitude range corresponding to the coverage area. and The sizes are respectively: remember For blocks The latitude of the center For blocks The longitude of the center is taken as follows: , ; Depend on ,in Let F be the phase difference between adjacent orbital satellites, and F be the phase factor, then: remember , , , Blocks Given the positions of the four vertices, then: = = = = = = = = ； Step S20: Based on the set of ground blocks, combined with the longitude information of the reverse seam and the inter-satellite connectivity, calculate the ground block connectivity matrix. The specific method is as follows: Step S21: Determine the connectivity status between blocks. When the ascent orbit of the first orbital plane satellite is located at longitude 0° ~ In the case of satellite reverse seams, the communication links between adjacent ground blocks are considered broken, and the connectivity is represented by ∞; except for the adjacent ground blocks corresponding to satellite reverse seams, the communication between other adjacent blocks corresponds to the inter-satellite links of the satellites covering that block, and the connectivity is represented by 1; non-adjacent blocks cannot communicate directly and are considered broken, and the connectivity is represented by ∞; communication within a block is represented by 0; thus, the ground block connectivity matrix is ​​obtained. ; Among them, elements Represents a block and blocks The connection between them It is the total number of blocks; Step S22, according to step S21, as the Earth rotates, when the ascending orbit of the first orbital plane satellite is located at longitude 0°- Between ~0°, the communication link between adjacent ground blocks corresponding to the satellite reverse seam is considered broken, and the connectivity is represented by ∞; except for the adjacent ground blocks corresponding to the satellite reverse seam, the communication between other adjacent blocks corresponds to the inter-satellite link of the satellite covering that block, and the connectivity is represented by 1; non-adjacent blocks cannot communicate directly and are considered broken, and the connectivity is represented by ∞; communication within a block is represented by 0; thus, the ground block connectivity matrix is ​​obtained. ; Step S23, and so on, the ascending orbit of the first orbital plane satellite moves in longitude by 100 degrees. The satellite reverse slit reaches a new block, obtaining a new connectivity matrix, until the satellite reverse slit returns to its initial position, completing one Earth rotation period T, and thus obtaining... Let there be a set of connectivity relations. ,in, Let i be the i-th connectivity matrix; Step S30: Based on the service intensity of each ground block and the ground block connectivity matrix, calculate the inter-block link load intensity and generate a ground block topology vector. The specific method is as follows: Based on the number of internet users in each block, the potential satellite network traffic for each block is obtained. This leads to the set of connectivity relationships. The corresponding inter-block link load strength set ={ },in, Represents the connectivity matrix The corresponding link load strength matrix; Among them, elements For blocks and blocks Link load strength between them, when At that time, the corresponding ,when Or when At that time, the corresponding = ; in, , Blocks and blocks Potential traffic For blocks and blocks The distance between centers; Among them, blocks and blocks Distance between centers The calculation method is as follows: in, and Representing blocks and blocks The latitude of the center point and Representing blocks and blocks Longitude of the center point Represents the radius of the Earth; Using blocks as nodes and inter-block link load strength as edges, generate a set of connectivity relationships. Corresponding topological graph vector ;in, Represents the connectivity matrix The corresponding topology table consists of a block set. Inter-block link load strength matrix composition; Step S40: Calculate the routing table for each ground block based on the ground block topology map vector, and generate the ground block routing table vector; Step S50: Based on the boundary conditions of the ground block and the satellite operation rules, calculate the time for each satellite to switch coverage blocks. The time for satellites to switch coverage blocks is referred to as the block switching time. Step S60: Upload the calculated ground block topology vector, ground block routing table vector, and block switching time to the landing satellite, and then spread them to other satellite nodes in the entire network from the landing satellite; Step S70: Each satellite selects a routing table that matches the current time from the ground block routing table vector based on its own latitude and longitude information and the block switching time, and uses the routing table to transmit data.

2. The polar-orbit constellation inter-satellite load balancing routing method based on topology switching according to claim 1, characterized in that, In step S40, a routing table is calculated for each ground block, generating a ground block routing table vector. Specifically, the method involves using the inter-block link load strength as weights and employing a minimum cost algorithm to calculate the topology map vector. Corresponding routing table vector For each path calculated, the weight of that path is increased by 1; in, Representation and topology table corresponding Zhang's routing table, express Each block has its own routing table, and each routing table maintains the routes from the current block to all other blocks at the current time.

3. The polar-orbit constellation inter-satellite load balancing routing method based on topology switching according to claim 2, characterized in that, The specific method for calculating the switching time of each satellite's coverage block in step S50 is as follows: After the satellite is powered on, the topology map is activated. and routing table Corresponding to the satellite's initial position, after the satellite arrives at the new block, a block handover is performed. The block handover time is calculated based on the latitudinal range of the ground block and the satellite's speed. = ; in, For the satellite's angular velocity, For the Earth's radius, For the orbital height, For gravitational constant, Earth mass; When the satellite reverse slot corresponds to a new block, a topology table switch and a routing table switch are performed. The switch times are calculated based on the longitude range spanned by the ground block and the Earth's rotation speed. = ,in, This refers to the Earth's rotation speed; After each topology switch, a phase deviation occurs between the satellite and the latitude of the corresponding coverage block after the topology switch. The phase deviation compensation time is calculated based on the phase deviation of the block latitude and the satellite's motion velocity. ;in, This represents the phase difference between satellites in adjacent orbits.

4. The polar-orbit constellation inter-satellite load balancing routing method based on topology switching according to claim 3, characterized in that, In step S60, the calculated ground block topology vector, ground block routing table vector, and block switching time are uploaded to the landing satellite, and then disseminated from the landing satellite to other satellite nodes in the entire network. The specific method is as follows: After the satellite is powered on, the ground station establishes a connection with the satellite covering the ground station. At this time, the satellite's identity changes to a landing satellite. The ground station uploads information packets consisting of the calculated ground block topology table, ground block routing table, and block switching time to the landing satellite, which then disseminates the information packets to other satellites in the network.

5. The polar-orbit constellation inter-satellite load balancing routing method based on topology switching according to claim 4, characterized in that, In step S70, each satellite, based on its own latitude and longitude information and the block switching time, selects a routing table from the ground block routing table vector that matches the current time as the routing table currently used by that satellite, and transmits data according to this routing table. The specific method is as follows: Each block has Zhang's routing table, corresponding to Each connection relationship is maintained in its routing table, which maintains the routes from the current block to all other blocks under that connection relationship. When a satellite enters the block, it undertakes the service requirements of that block. Based on its own latitude and longitude information and the block switching time, it determines the current ground block connectivity and selects the routing table that matches the current time from the ground block routing table vector as the routing table currently used by the satellite. Based on the routing table currently used by the block, it finds the transmission path from the source node to the destination node. ; in, Indicates the source node of the ground block. The node representing the destination of the ground block. Indicates the communication nodes in the transmission path; The satellite selects a satellite that covers a block of the transmission path at the current time to transmit the data, based on the transmission path. When a satellite leaves the block, a subsequent satellite takes over the services of that block and performs a link switch.

6. A polar-orbit constellation inter-satellite load balancing routing system based on topology switching, characterized in that, It includes a ground control center module and a satellite service transmission module; among which: The ground control center module is used to divide ground blocks according to satellite constellation parameters, and obtain a ground block connectivity matrix by combining reverse seam longitude information and inter-satellite connectivity relationships; based on the service intensity of ground blocks and the ground block connectivity matrix, it calculates the inter-block link load intensity and obtains a ground block topology table; based on the ground block topology table, it calculates a routing table for each block; based on the ground block boundary conditions and satellite operation patterns, it calculates the timing pattern of each satellite switching coverage blocks; and it uploads the calculated topology table, routing table, and block switching time to the satellites. The satellite service transmission module is used to select a routing table that matches the current time from the ground block routing table vector based on its own latitude and longitude information and the block switching time, and then transmit data according to the routing table. The ground control center module includes: The block partitioning module is used to divide the ground into blocks, calculate the boundary conditions of the ground blocks, and obtain a set of ground blocks. The specific method is as follows: Based on satellite constellation type, the ground is divided into latitude and longitude regions. The set of ground blocks is denoted as _block_, where each block corresponds to a satellite covering that block. ,in, The coverage of the i-th orbital plane satellite in the initial state There are 10 blocks, each block being 100 blocks in size. ; in, It is the total number of satellites in the constellation. It refers to the number of orbital planes of a constellation. It refers to the number of satellites in each orbital plane. The latitude range corresponding to the coverage area. The longitude range corresponding to the coverage area. and The sizes are respectively: remember For blocks The latitude of the center For blocks The longitude of the center is taken as follows: , ; Depend on ,in Let F be the phase difference between adjacent orbital satellites, and F be the phase factor. remember , , , Blocks The positions of the four vertices, then = = = = = = = = The connectivity matrix acquisition module is used to calculate the ground block connectivity matrix based on the ground block set, combined with the reverse seam longitude information and satellite inter-satellite connectivity. The specific method is as follows: Step S21: Determine the connectivity status between blocks. When the ascent orbit of the first orbital plane satellite is located at... ~ In the case of satellite reverse seams, the communication links between adjacent ground blocks are considered broken, and the connectivity is represented by ∞; except for the adjacent ground blocks corresponding to satellite reverse seams, the communication between other adjacent blocks corresponds to the inter-satellite links of the satellites covering that block, and the connectivity is represented by 1; non-adjacent blocks cannot communicate directly and are considered broken, and the connectivity is represented by ∞; communication within a block is represented by 0; thus, the ground block connectivity matrix is ​​obtained. ; Among them, elements Represents a block and blocks The connection between them It is the total number of blocks; Step S22, according to step S21, as the Earth rotates, when the ascending orbit of the first orbital plane satellite is located at longitude... - Between ~0°, the communication link between adjacent ground blocks corresponding to the satellite reverse seam is considered broken, and the connectivity is represented by ∞; except for the adjacent ground blocks corresponding to the satellite reverse seam, the communication between other adjacent blocks corresponds to the inter-satellite link of the satellite covering that block, and the connectivity is represented by 1; non-adjacent blocks cannot communicate directly and are considered broken, and the connectivity is represented by ∞; communication within a block is represented by 0; thus, the ground block connectivity matrix is ​​obtained. ; Step S23, and so on, the ascending orbit of the first orbital plane satellite moves in longitude by 100 degrees. The satellite reverse slit reaches a new block, obtaining a new connectivity matrix, until the satellite reverse slit returns to its initial position, completing one Earth rotation period T, and thus obtaining... Let there be a set of connectivity relations. ,in, Let i be the i-th connectivity matrix; The ground block topology vector acquisition module is used to calculate the inter-block link load strength based on the service intensity of each ground block and the ground block connectivity matrix, and generate a ground block topology vector. The specific method is as follows: Based on the number of internet users in each block, the potential satellite network traffic for each block is obtained. This leads to the set of connectivity relationships. The corresponding inter-block link load strength set ={ };in, Represents the connectivity matrix The corresponding link load strength matrix; Among them, elements For blocks and blocks Link load strength between them, when At that time, the corresponding ,when Or when At that time, the corresponding = ; in, , Blocks and blocks Potential traffic For blocks and blocks The distance between centers; Among them, blocks and blocks Distance between centers The calculation method is as follows: in, and Representing blocks and blocks The latitude of the center point and Representing blocks and blocks Longitude of the center point Represents the radius of the Earth; Using blocks as nodes and inter-block link load strength as edges, generate a set of connectivity relationships. Corresponding topological graph vector ;in, Represents the connectivity matrix The corresponding topology table consists of a block set. Inter-block link load strength matrix composition; The ground block routing table vector acquisition module is used to calculate the routing table for each block based on the ground block topology map vector and generate the ground block routing table vector. The satellite handover coverage block pattern acquisition module is used to calculate the time for each satellite to handover coverage block based on the ground block boundary conditions and the satellite operation pattern. The ground station uploading module is used to upload the calculated topology vector, routing table vector, and block switching time to the landing satellite, which then spreads them to other satellite nodes in the network.

7. The polar-orbit constellation inter-satellite load balancing routing system based on topology switching according to claim 6, characterized in that, The ground block routing table vector acquisition module is used to calculate the routing table for each block based on the ground block topology map vector, and generate the ground block routing table vector. The specific method is as follows: Using inter-block link load strength as weights, and employing a minimum cost algorithm, the vectors in the topology graph are calculated. Corresponding routing table vector For each path calculated, the weight of that path is increased by 1; in, Representation and topology table corresponding Zhang's routing table, express Each block has one routing table, and each routing table maintains the routes from the current block to all other blocks at the current time. The satellite handover coverage block pattern acquisition module is used to calculate the handover time for each satellite coverage block based on ground block boundary conditions and satellite operation patterns. The specific method is as follows: After the satellite is powered on, the topology map is activated. and routing table Corresponding to the satellite's initial position, after the satellite arrives at the new block, a block handover is performed. The block handover time is calculated based on the latitudinal range of the ground block and the satellite's speed. = ; in, For the satellite's angular velocity, For the Earth's radius, For the orbital height, For gravitational constant, Earth mass; When the satellite reverse slot corresponds to a new block, a topology table switch and a routing table switch are performed. The switch times are calculated based on the longitude range spanned by the ground block and the Earth's rotation speed. = ,in, This refers to the Earth's rotation speed; After each topology switch, a phase deviation occurs between the satellite and the latitude of the corresponding coverage block after the topology switch. The phase deviation compensation time is calculated based on the phase deviation of the block latitude and the satellite's motion velocity. ,in, The phase difference between satellites in adjacent orbits; The ground station uploading module is used to upload calculated topology vectors, routing table vectors, block switching times, and other information to the landing satellite, which then disseminates this information to other satellite nodes across the network. The specific method is as follows: After the satellite is powered on, the ground station establishes a connection with the satellite covering the ground station. At this time, the satellite's identity changes to a landing satellite. The ground station will compile the calculated topology table, routing table, block switching time and other information into information packets and upload them to the landing satellite. The landing satellite will then spread the packets to other satellites in the entire network. The satellite service transmission module includes: The routing table selection module is used by the satellite to select a routing table from the ground block routing table vector that matches the current time, based on its own latitude and longitude information and the block switching time. The specific method is as follows: Each block has Zhang's routing table, corresponding to Each connection relationship is maintained in its routing table, which maintains the routes from the current block to all other blocks under that connection relationship. When a satellite enters the block, it undertakes the service requirements of that block. Based on its own latitude and longitude information and the block switching time, it determines the current ground block connectivity and selects the routing table that matches the current time from the ground block routing table vector as the routing table currently used by the satellite. Based on the routing table currently used by the block, it finds the transmission path from the source node to the destination node. ; in, Indicates the source node of the ground block. The node representing the destination of the ground block. Indicates the communication nodes in the transmission path; The service transmission module is used by the satellite to select satellites that cover the current time block in the transmission path according to the transmission path, and transmit the data. When a satellite leaves the block, a subsequent satellite takes over the services of that block and performs a link switch.

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