A Routing Method for a Low-Earth Orbit Inclined Orbit Constellation Network

Abstract

The present application relates to a routing method for a low-earth orbit inclined orbit constellation network, including the following steps: Step 1, estimate the connectivity status of all inter-orbit inter-satellite links by obtaining the estimated connectable duration of a single inter-orbit inter-satellite link and obtaining the offset matrix of the switching moments of the connectivity status of all inter-orbit inter-satellite links; Step 2, based on the estimated connectivity status of all inter-orbit inter-satellite links; The present invention uses the inter-satellite ranging results and the periodic law of the movement of the constellation system to estimate the on-off status of all inter-orbit inter-satellite links within the entire constellation, and uses the remaining connectable duration of the inter-orbit inter-satellite links as an important parameter for evaluating the link value. Based on the complete constellation network connection relationship table and the constellation network link value index table, a constellation network routing method is realized, effectively avoiding the problems of increased cross-orbit communication delay and packet loss rate caused by the sudden disconnection of inter-orbit inter-satellite links, and overcoming the difficulties caused by the change of the constellation network topology to the routing of the low-earth orbit inclined orbit constellation network.

Description

Technical Field

[0001] This application relates to the technical field of low-earth orbit satellite constellation network routing, and in particular to a routing method for a low-earth orbit inclined orbit constellation network. Background Art

[0002] Low-earth orbit satellite communication constellations are currently the biggest hotspots in the field of satellite research and applications. Communication networks based on satellite constellations will become an important part of the future global network. The routing algorithm of the constellation network is the key to realizing constellation network communication. The difficulty in its design lies in the fact that the on-off state of the inter-orbit satellite links is constantly changing, resulting in the continuous change of the constellation network topology. If the inter-orbit satellite link is disconnected and not detected in time, it will lead to an increase in the transmission delay of cross-orbit communication frames and even the loss of communication frames.

[0003] Currently, the routing algorithms applied to constellation networks are roughly divided into three types, namely, snapshot-based routing algorithms, virtual node-based routing algorithms, and routing algorithms derived from mobile Ad Hoc networks. Among them, snapshot-based routing algorithms are mainly applied to polar orbit constellations and are not suitable for inclined orbit constellations. Similarly, virtual node-based routing algorithms are also mainly applied to polar orbit constellations and are only suitable for constellations with uniform satellite distribution and not for constellations with non-uniform satellite distribution. For routing algorithms derived from mobile Ad Hoc networks, although the satellite nodes in the constellation network have mobility and the network topology is variable, which is consistent with the characteristics of mobile Ad Hoc networks, the satellite nodes in the constellation network are relatively sparse, the inter-satellite distance is far, and the signal propagation delay is large. Therefore, applying mobile Ad Hoc network routing algorithms to constellation networks usually does not achieve ideal results. Moreover, when applying routing algorithms derived from mobile Ad Hoc networks to constellation networks, the characteristics of the periodic switching of the on-off state of inter-orbit satellite links and the change of network topology cannot be fully utilized. Therefore, the performance of this type of routing algorithm in constellation networks needs to be improved. Summary of the Invention

[0004] In order to solve the problems of large cross-orbit transmission delay and high packet loss rate of communication frames caused by the change of the connectivity state of inter-orbit satellite links in the existing constellation network cross-orbit routing in the above background art, this application provides a routing method for a low-earth orbit inclined orbit constellation network.

[0005] A routing method for a low-earth orbit inclined orbit constellation network provided by this application adopts the following technical solutions:

[0006] A routing method for a low-earth orbit inclined orbit constellation network includes the following steps:

[0007] Step 1: Estimate the connectivity status of all inter-orbit inter-satellite links by obtaining the estimated connectable duration of a single inter-orbit inter-satellite link and the offset matrix of the connectivity status switching moments of all inter-orbit inter-satellite links.

[0008] Step 2: Obtain the constellation network connection relation table and the constellation network link value index table based on the estimated connectivity status of all inter-orbit inter-satellite links.

[0009] Step 3: Select the optimal route for information transmission between any two nodes within the constellation according to the constellation network connection relation table and the constellation network link value table.

[0010] By adopting the above technical solutions, the whole process management from link state estimation to optimal route selection is realized step by step. In Step 1, by accurately estimating the connectable duration and the connectivity status switching moment of the inter-orbit link, reliable basic data is laid for the subsequent steps; in Step 2, by comprehensively considering the connectivity status and value index of the links in the constellation network, the constellation network connection relation table and the constellation network link value table are established, providing a comprehensive evaluation criterion for route selection; in the third step, the efficiency maximization of information transmission is achieved by selecting the optimal path. The overall method is applicable to low-orbit constellation networks with frequent dynamic continuous changes, improving the information transmission performance and communication efficiency of the constellation system, and being able to adapt to the requirements of dynamic changes in network topology.

[0011] Optionally, in the above Step 1, the method for estimating the connectable duration of a single inter-orbit inter-satellite link is: based on the close relationship between the distance between inter-orbit satellites, the sign of the relative velocity between satellites, and the connectivity of the corresponding inter-orbit inter-satellite link, use the measured results of the inter-satellite distance and relative velocity between two connectable inter-orbit satellites to estimate the duration for which the connectivity status of this inter-orbit inter-satellite link can last.

[0012] By adopting the above technical solutions, the correlation between the link connectivity status and orbital parameters is scientifically revealed. This method is based on measured distance and speed data, can dynamically calculate the continuous connection time of the link, and effectively avoids the error problems caused by over-reliance on empirical models in traditional methods. At the same time, this estimation method has stronger adaptability for complex inclined orbit constellations, can provide accurate duration prediction for dynamic route optimization, and improves the stability and reliability of the entire network.

[0013] Optionally, in the above Step 1, the method for obtaining the offset matrix of the connectivity status switching moments of all inter-orbit inter-satellite links includes the following steps:

[0014] S1: Analyze the moments when the connectivity status of all inter-orbit inter-satellite links switches within one orbital period according to the periodicity of the constellation system's motion and the distribution law of inter-orbit inter-satellite links.

[0015] S2. Taking one of the links as a reference benchmark, determine the time offset of the moment when all inter-orbit inter-satellite links switch to the connected state relative to the moment when the reference inter-orbit inter-satellite link switches to the connected state, so as to obtain the offset matrix of the moment when the inter-orbit inter-satellite links in the constellation network switch to the connected state.

[0016] By adopting the above technical solution, the management difficulty of dynamic links is simplified, and a reliable basis is provided for the connection state prediction and routing optimization of the constellation network. Especially in the deployment of high-density constellations, the stability and communication efficiency of the network can be significantly improved.

[0017] Optionally, in step one, the connection states of all inter-orbit inter-satellite links are the connection states at the current moment or within a certain future time range.

[0018] By adopting the above technical solution, through the acquisition of this real-time or predictive connection state, the possibility of dynamic adjustment is provided for subsequent route selection, which can effectively cope with the problem of frequent link changes in the constellation system and ensure the continuity and reliability of the information transmission path.

[0019] Optionally, in step two, the methods for obtaining the constellation network connection relation table and the constellation network link value index table are as follows:

[0020] According to the connection states of all inter-orbit inter-satellite links in the constellation network, the connection relation table of inter-orbit satellites in the constellation network at a specified moment can be obtained. At the same time, the remaining connectable duration of each inter-orbit satellite starting from the specified moment can also be obtained, and this duration is used as one of the parameters for evaluating the link value index of the corresponding inter-orbit inter-satellite link, generating the inter-orbit inter-satellite link value index table;

[0021] Combine the obtained connection relation table of inter-orbit satellites in the constellation network with the connection relation table of in-orbit satellites to generate the constellation network connection relation table;

[0022] Combine the obtained inter-orbit inter-satellite link value index table with the in-orbit inter-satellite link value index table to generate the constellation network link value index table.

[0023] By adopting the above technical solution, through constructing the connection relation table and the link value index table of the constellation network, a comprehensive characterization of the network topology structure is realized. This method combines inter-orbit links and in-orbit links to form a unified connection relation table, so as to accurately reflect the connection relation between any nodes in the constellation. At the same time, by generating a value index table with the link connectable duration as the main parameter, the communication value of the link can be quantitatively evaluated, providing a reliable reference for route selection. This combination method has both a global perspective and local optimization capabilities, and can significantly improve the scientificity and rationality of route selection in a dynamic network environment.

[0024] Optionally, for the inter-orbit inter-satellite link value index in the constellation network link value index table, the link available connection duration is used as one of the evaluation parameters, and the inter-orbit inter-satellite link value index table is used as the basis for route selection, so that when a communication frame is transmitted across orbits, the inter-orbit inter-satellite link that is currently connected and has a long remaining sustainable connection time is preferentially selected as the cross-orbit transmission path.

[0025] By adopting the above technical solution, it is possible to preferentially select a link that is currently connected and has a relatively long remaining available connection duration for cross-orbit transmission, thereby reducing the transmission delay and data packet loss risk caused by frequent link switching.

[0026] Optionally, in step three, when selecting the optimal route for information transmission between any two nodes within the constellation, it is necessary to consider the time taken for the communication frame to reach a certain node in the path, as well as the changes in the on-off state and value index of the inter-orbit inter-satellite link during this period.

[0027] By adopting the above technical solution, the route for the communication frame is selected not only based on the constellation network connection relationship table and link value table at a certain fixed moment, but also considering the changes in the inter-orbit inter-satellite connection relationship and value index during the transmission process of the communication frame, so as to select the real-time optimal route for the communication frame. This dynamic adjustment mechanism makes the route selection more accurate and effectively reduces the risk of transmission failure caused by sudden changes in link status or value changes.

[0028] Optionally, in step three, when selecting the optimal route for information transmission between any two nodes within the constellation, it is necessary to select the optimal transmission path from the current node to the destination node according to the latest constellation network connection relationship table and link value table before each hop of transmission, so as to cope with the abnormal changes in the constellation network connection relationship table or link value index table caused by special situations.

[0029] Optionally, the special situations include sudden satellite failure and / or sudden interference to the inter-satellite link.

[0030] By adopting the above technical solution, not only the flexibility and adaptability of route selection are improved, but also the transmission failure rate caused by abnormal changes is greatly reduced, further enhancing the stability and reliability of the low-earth orbit constellation network.

[0031] In summary, the present application includes at least one of the following beneficial technical effects:

[0032] The present invention utilizes the inter-satellite ranging results and the periodic law of the constellation system's movement to estimate the on-off states of all inter-orbit inter-satellite links within the entire constellation, and takes the remaining connectable duration of the inter-orbit inter-satellite links as an important parameter for evaluating the link value. Based on the complete constellation network connection relationship table and link value table, a constellation network routing method is realized, effectively avoiding the problems of increased cross-orbit communication delay and packet loss rate caused by the sudden disconnection of inter-orbit inter-satellite links, and overcoming the difficulties caused by the topological changes of the constellation network to the routing of low-earth orbit inclined orbit constellation networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a constellation configuration diagram of the present invention;

[0034] Figure 2 It is a schematic diagram of the curve of the inter-orbit inter-satellite distance changing with time and the connectable window of the present invention;

[0035] Figure 3 It is a schematic diagram of the inter-orbit inter-satellite position relationship of the present invention;

[0036] Figure 4 It is an error curve for estimating the connectable duration of inter-orbit inter-satellite links using the inter-satellite ranging results at different times of the present invention;

[0037] Figure 5 It is a schematic diagram of the connectable periods of different inter-orbit inter-satellite links between Orbit 1 and Orbit 2 of the present invention;

[0038] Figure 6 It is a schematic diagram of the occurrence times of the on-off states of all inter-orbit inter-satellite links within one operating cycle of a constellation system of the present invention;

[0039] Figure 7 It is the simulation result of the inter-orbit communication delay when the method of the present invention is not used;

[0040] Figure 8 It is the simulation result of the inter-orbit communication delay when the method of the present invention is used;

[0041] Figure 9 It is a flowchart of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The following further describes the present application in detail with reference to the accompanying drawings.

[0043] The embodiments of the present application disclose a routing method for a low-earth orbit inclined orbit constellation network, including the following three steps.

[0044] Step 1: Estimate the connection states of all inter-orbit inter-satellite links by obtaining the estimations of the connectable durations of single inter-orbit inter-satellite links and the offset matrix of the switching moments of the connection states of all inter-orbit inter-satellite links. The connection states of all inter-orbit inter-satellite links are the connection states at the current moment or within a certain time range in the future.

[0045] Specifically, the method for estimating the connectable duration of a single cross-orbit inter-satellite link is as follows: Based on the close relationship between the distance between cross-orbit satellites, the sign of the relative velocity between satellites, and the connectivity of the corresponding cross-orbit inter-satellite link, the measured results of the inter-satellite distance and relative velocity between connectable cross-orbit satellites are used to estimate the duration for which the connectivity state of the cross-orbit inter-satellite link can persist.

[0046] Specifically, as Figure 9 shown, the method for obtaining the offset matrix of the connectivity state switching moments of all cross-orbit inter-satellite links includes the following steps:

[0047] S1. Analyze the moments when the connectivity states of all cross-orbit inter-satellite links switch within one orbital period based on the periodicity of the constellation system's motion and the distribution law of cross-orbit inter-satellite links;

[0048] S2. Taking one link as a reference benchmark, determine the time offset of the moments when the connectivity states of all cross-orbit inter-satellite links switch relative to the moment when the connectivity state of the reference cross-orbit inter-satellite link switches, so as to obtain the offset matrix of the connectivity state switching moments of the cross-orbit inter-satellite links in the constellation network.

[0049] Step 2. Based on the estimated connectivity states of all cross-orbit inter-satellite links, obtain the connection relation table of the constellation network and the link value index table of the constellation network.

[0050] Specifically, the method for obtaining the connection relation table of the constellation network and the link value index table of the constellation network is as follows:

[0051] Based on the connectivity states of all cross-orbit inter-satellite links in the constellation network, the connection relation table of cross-orbit satellites in the constellation network at a specified moment can be obtained. At the same time, the remaining connectable duration of each cross-orbit satellite starting from the specified moment can also be obtained, and this duration is used as one of the parameters for evaluating the link value index of the corresponding cross-orbit inter-satellite link to generate the link value index table of cross-orbit inter-satellite links;

[0052] Combine the obtained connection relation table of cross-orbit satellites in the constellation network with the connection relation table of in-orbit satellites to generate the connection relation table of the constellation network;

[0053] Combine the obtained link value index table of cross-orbit inter-satellite links with the link value index table of in-orbit inter-satellite links to generate the link value index table of the constellation network.

[0054] Step 3. Based on the connection relation table of the constellation network and the link value table of the constellation network, select the optimal route for information transmission between any two nodes within the constellation.

[0055] Specifically, among the value indexes of the inter-orbit inter-satellite links in the constellation network link value index table, the value index of the inter-orbit inter-satellite link uses the link connectable duration as one of the evaluation parameters. Taking the inter-orbit inter-satellite link value index table as the basis for route selection, when a communication frame is transmitted across orbits, it preferentially selects an inter-orbit inter-satellite link that is currently connected and has a long remaining sustainable connection time as the cross-orbit transmission path. The purpose is to avoid sending the communication frame to a satellite where an inter-orbit inter-satellite link cannot be established currently or the inter-orbit inter-satellite link is about to disconnect, reducing the latency and packet loss rate of the communication frame during cross-orbit transmission.

[0056] Specifically, in step 3, when selecting the optimal route for information transmission between any two nodes within the constellation, it is necessary to consider the time taken for the communication frame to reach a certain node in the path, as well as the changes in the on / off state and value index of the inter-orbit inter-satellite link during this period. That is, instead of simply selecting a route for the communication frame based on the constellation network connection table and link value table at a fixed moment, it takes into account the changes in the inter-orbit inter-satellite connection relationship and value index during the transmission process of the communication frame, and selects the real-time optimal route for the communication frame.

[0057] Specifically, in step 3, when selecting the optimal route for information transmission between any two nodes within the constellation, not only the best route for the communication frame is selected before the first-hop transmission, but the optimal transmission path from the current node to the destination node needs to be selected according to the latest constellation network connection table and link value table before each hop of transmission, in order to cope with abnormal changes in the constellation network connection table or link value index table caused by special situations. The special situations include sudden satellite failure and / or sudden interference of the inter-satellite link. When there are no special situations, the best transmission path of the communication frame obtained at each intermediate node is a part of the best transmission path selected for the communication frame at the source node.

[0058] To further illustrate this low-Earth inclined orbit constellation network routing method, the following gives a specific embodiment actually applied to the demonstration and verification task of the "Huanjiang-1" micro-nano satellite constellation network in Zhuji Huanjiang Laboratory.

[0059] As Figure 1 shown, the low-Earth inclined orbit constellation of this embodiment consists of 50 satellites in 5 orbital planes, with 10 satellites evenly distributed in each orbital plane. Among them, Figure 1 the black dots represent satellites, and the lines are satellite orbits, with a total of 5. Next, first, it is explained how to determine the remaining connectable duration of the inter-orbit inter-satellite link based on the measurement results of the inter-orbit inter-satellite distance and the sign of the relative velocity between satellites.

[0060] As Figure 2As shown, the curve of the inter-satellite distance between two adjacent non-coplanar satellites in this embodiment has the same period as the process of the on-off state of the corresponding non-coplanar inter-satellite link changing with time. This shows that there is a one-to-one correspondence between the on-off state of the non-coplanar inter-satellite link and the interval where the non-coplanar inter-satellite distance is located. This means that, given the non-coplanar inter-satellite distance, the current on-off state of the non-coplanar inter-satellite link can be estimated. Further observation shows that the interval in which the non-coplanar inter-satellite link is in a connected state is centered around the moment when the non-coplanar inter-satellite distance reaches its maximum value. At the same time, within this interval, the curve of the non-coplanar inter-satellite distance change is symmetric about the left and right. On the left side of the interval, the non-coplanar inter-satellite distance gradually increases, indicating that the relative velocity between the non-coplanar satellites is positive. On the right side of the interval, the non-coplanar inter-satellite distance gradually decreases, indicating that the relative velocity between the non-coplanar satellites is negative. Therefore, by combining the measured magnitude of the non-coplanar inter-satellite distance at the current moment and the sign of the relative motion velocity between the non-coplanar satellites, the specific position of the non-coplanar inter-satellite link in the visible interval can be determined, and further, the time length for which the non-coplanar inter-satellite link can remain in a connected state can be determined.

[0061] As Figure 3 shown, the distance between non-coplanar satellites S1 and S2 is equal to the modulus of the vector The angle between the vectors and is denoted as , then the non-coplanar inter-satellite distance (1).

[0062] And has the following relationship with the phases and of their respective orbital planes in the two satellites:

[0063] (2)

[0064] Wherein, the two coefficients and are equal to

[0065]

[0066] In the above formula, represents the orbital inclination, and are the right ascensions of the ascending nodes of the orbital planes where the two satellites are located, respectively. and are quantities that change with time. Therefore, the non-coplanar inter-satellite distance is related to time and through .

[0067] According to formulas (1) and (2), the following relational formula can be obtained:

[0068] (3)

[0069] Let , where represents the angular velocity of the satellite. Equation (3) represents the relationship between the inter-satellite distance and time . Theoretically, given the magnitude of the inter-satellite distance between non-coplanar satellites, the time position of this distance within the change cycle can be calculated through Equation (3).

[0070] In this embodiment, the maximum length of the time window during which the inter-satellite link between non-coplanar satellites can be connected is 1510 s. At the same time, as mentioned before, this time window is symmetric about the moment when the inter-satellite distance between non-coplanar satellites reaches its maximum value. This indicates that when the inter-satellite distance between non-coplanar satellites reaches its maximum value, 755 s of the connectable time window of the inter-satellite link between non-coplanar satellites has elapsed. And according to Equation (3), when the inter-satellite distance takes its maximum value, it is calculated that . Therefore, if represents the time that has elapsed in the connectable time window of the inter-satellite link between non-coplanar satellites, then

[0071] (4)

[0072] where represents the relative velocity between satellites, is the sign function.

[0073] However, the measurement of the inter-satellite distance will deviate under the influence of factors such as relative motion between satellites, equipment delay, forwarding delay, and ionospheric delay, resulting in an error in the estimation of . Figure 4 gives the calculation result of the estimation error magnitude of when the ranging is approximately 60 m. It can be seen that when the inter-satellite distance is close to its maximum value, the estimation error of reaches 5.105 s; at other times, the estimation error of is less than 0.5 s, and the minimum estimation error is approximately 0.022 s. Therefore, the estimation of should be avoided when the inter-satellite distance is close to its maximum value.

[0074] As Figure 5 shown, in the constellation of this embodiment, the on-off states of different inter-satellite links between non-coplanar satellites change with time in a similar periodic manner. Specifically, at Figure 5The time periods for establishing and disconnecting the connections of 5 inter-orbit inter-satellite links on orbit 1 and orbit 2 are given. In the vertical coordinate system, 1C5-2C4 represents the inter-orbit inter-satellite link between satellite C5 on orbit 1 and satellite C4 on orbit 2, and other markings follow the same pattern. This means that there is a fixed time offset between the switching moments of the on / off states of different inter-orbit inter-satellite links. Figure 6 The moments when the on / off states of different inter-orbit inter-satellite links change within one operating cycle of a constellation system are given. The offset magnitude matrix table of the switching moments of different inter-orbit inter-satellite links in the constellation of this embodiment is shown in Table 1 below:

[0075] Table 1

[0076]

[0077] In the above table, the two numbers (x, y) in each row of the first column represent orbit x and orbit y. In the corresponding row, the first sub-row represents the corresponding inter-orbit inter-satellite link. For example, mCn represents satellite Cn on orbit m. mCn-xCy represents the inter-orbit inter-satellite link between satellite Cn on orbit m and satellite Cy on orbit x; the second sub-row represents the offset magnitude between the connection establishment moment of the corresponding inter-orbit inter-satellite link and the connection establishment moment of the 1C1-2C5 inter-orbit inter-satellite link.

[0078] When the position of one inter-orbit inter-satellite link in the on / off state change cycle at a specified moment is known, the positions of all other inter-orbit inter-satellite links in their own on / off state change cycles at the same moment can be calculated according to the offsets given in the table, that is, their on / off states can be deduced. If it is deduced that an inter-orbit inter-satellite link is in the connected state at a specified moment, then it can also be calculated how long it will take for this inter-satellite link to disconnect. Conversely, if it is deduced that an inter-orbit inter-satellite link is in the disconnected state at a specified moment, then it can be calculated how long it will take for this inter-satellite link to become connected. The remaining connectable duration of the inter-orbit inter-satellite link can be used as one of the evaluation factors for the value index of this inter-orbit inter-satellite link and used as a basis for cross-orbit route selection.

[0079] Combining the connection relationships of in-orbit satellites and the connection relationships of inter-orbit satellites can generate a constellation network connection relationship table. At the same time, combining the value indices of in-orbit inter-satellite links and the value indices of inter-orbit inter-satellite links can generate a constellation network link value table. The inter-satellite link value index is a comprehensive manifestation of link reliability and delay, and it can be jointly determined by multi-dimensional parameters such as the bit error rate, interference situation, and delay of the link. Combining the constellation network connection relationship table and the link value table can realize the constellation network routing function and select the optimal transmission path for communication frames within the entire constellation network.

[0080] As a comparison, Figure 7It shows the delay situation of sending communication frames between satellites in two adjacent orbits when the "low-earth inclined orbit constellation network routing method" of this embodiment is not adopted in the constellation of this embodiment. When the "low-earth inclined orbit constellation network routing method" of this embodiment is not adopted, it is assumed that each satellite node does not know the on-off state of the inter-orbit inter-satellite link between the current orbit and the adjacent orbit. Therefore, when sending a communication frame to a satellite in an adjacent orbit, first determine whether the current satellite can establish an inter-orbit inter-satellite link with the adjacent orbit. If yes, directly send it to the adjacent orbit. If not, send it to the next satellite in the same orbit along a fixed direction until the communication frame is sent to the satellite that can establish an inter-orbit inter-satellite link with the adjacent orbit.

[0081] Figure 8 It shows the delay situation of sending communication frames between satellites in two adjacent orbits when the "low-earth inclined orbit constellation network routing method" of this embodiment is adopted in the constellation of this embodiment. Compare Figure 7 and Figure 8 , it can be seen that the cross-orbit transmission delay of the communication frame has been greatly improved after adopting the "low-earth inclined orbit constellation network routing method" of this embodiment.

[0082] The above are all preferred embodiments of this application, and the protection scope of this application is not limited accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A low-orbit inclined orbit constellation network routing method, characterized in that: The following steps are involved: Step 1: By estimating the connectable duration of a single inter-satellite link and obtaining a connection state switching time offset matrix of all inter-satellite links, the connectivity state of all inter-satellite links is estimated; Step 2: Obtain a constellation network connection relationship table and a constellation network link value index table by estimating the connectivity status of all inter-satellite links in different orbits; wherein the method for obtaining the constellation network connection relationship table and the constellation network link value index table is: According to the connectivity status of all inter-orbital links of the constellation network, a connection relationship table of inter-orbital satellites of the constellation network at a specified time is obtained. At the same time, the remaining connectable time of each inter-orbital satellite from the specified time is obtained, and the time is used as one of the parameters for evaluating the value index of the corresponding inter-orbital link to generate an inter-orbital link value index table; The obtained constellation network different-orbit satellite connection relationship table is combined with the same-orbit satellite connection relationship table to generate a constellation network connection relationship table; The obtained inter-satellite link value index table of different orbits is combined with the inter-satellite link value index table of the same orbit to generate a constellation network link value index table; Step 3: According to the constellation network connection relationship table and the constellation network link value index table, select the optimal route for information transmission between any two nodes within the constellation range.

2. A low-orbit inclined orbit constellation network routing method according to claim 1, characterized in that: In the step 1, the method for estimating the connectable duration of a single inter-satellite link in an off-orbital orbit is as follows: based on the close relationship between the distance between the off-orbital satellites, the sign of the inter-satellite relative velocity and the connectivity of the corresponding inter-satellite link in an off-orbital orbit, the inter-satellite distance and relative velocity measurement results between a connectable off-orbital satellite are used to estimate the duration of the connectable state of the inter-satellite link in an off-orbital orbit.

3. A low-orbit inclined orbit constellation network routing method according to claim 1, characterized in that: In the step 1, the method for obtaining the connection state switching time offset matrix of all inter-orbital satellite links comprises the following steps: S1. According to the periodicity of the motion of the constellation system and the distribution law of inter-satellite links in different orbits, the moment when the connection state of all inter-satellite links in different orbits switches within one orbital period is analyzed; S2. Taking one of the links as a reference, determine the time offset of the time when the connectivity state of all inter-orbital satellite links switches relative to the time when the connectivity state of the benchmark inter-orbital satellite link switches, so as to obtain the constellation network inter-orbital satellite link connectivity state switching time offset matrix.

4. A low-orbit inclined orbit constellation network routing method according to claim 1, characterized in that: In the step 1, the connectivity status of all inter-satellite links in different orbits is the connectivity status at the current time or within a certain time range in the future.

5. A low-orbit inclined orbit constellation network routing method according to claim 1, characterized in that: The inter-orbital inter-satellite link value index in the constellation network link value index table uses the link connectivity time as one of the evaluation parameters, and uses the inter-orbital inter-satellite link value index table as the basis for route selection, so that when communication frames are transmitted across orbits, they give priority to selecting the inter-orbital inter-satellite link that is currently connected and has a long remaining sustainable connectivity time as the inter-orbit transmission path.

6. A low-orbit inclined orbit constellation network routing method according to claim 1, characterized in that: In step 3, when selecting the optimal route for information transmission between any two nodes within the constellation, it is necessary to consider the time taken for the communication frame to be transmitted to a certain node in the path, as well as the changes in the on / off state and value index of the inter-satellite link in different orbits during this period.

7. A low-orbit inclined orbit constellation network routing method according to claim 1, characterized in that: In the step three, when selecting the optimal route for information transmission between any two nodes within the constellation range, it is necessary to select the optimal transmission path from the current node to the destination node according to the latest constellation network connection relationship table and the constellation network link value index table before each hop transmission to cope with abnormal changes in the constellation network connection relationship table or the constellation network link value index table caused by special circumstances.

8. A low-orbit inclined orbit constellation network routing method according to claim 7, characterized in that: The special circumstances described include sudden failure of a satellite and / or sudden disturbance of an intersatellite link.

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