Hybrid orbit constellation dynamic routing method based on OSPF improvement

Abstract

The invention discloses a hybrid orbit constellation dynamic routing method based on OSPF improvement, and belongs to the technical field of network routing. According to the method, a static routing table is adopted in a backbone area with a relatively fixed topological structure by utilizing the characteristic of topological change of a mixed track, an access area with relatively large topological structure change is divided into a plurality of sub-areas, static routing is adopted in the sub-areas, and dynamic routing is adopted in the sub-areas. Through the coupling design of the physical partition and the logic partition, the contradiction between the high-speed change of the satellite network topology and the routing convergence speed of the whole network is solved, the topology change is locally updated, and the global dynamic routing range is reduced by more than 70%.

Description

Technical Field

[0001] This invention relates to a hybrid orbit constellation dynamic routing method based on an improved Open Shortest Path First (OSPF) algorithm, belonging to the field of network routing technology. Background Technology

[0002] In recent years, satellite network technology has developed rapidly, and inter-satellite routing technology has become the core hub for achieving stable interconnection of highly dynamic topologies and efficient cross-orbit distribution of massive amounts of data. Compared to stable terrestrial topologies, constellation networks exhibit several challenges. First, the nodes within a constellation network operate at high speeds, resulting in a highly dynamic network topology. Second, the frequent changes in the positional relationships between satellites due to their orbits cause fluctuations in link effectiveness and stability. Furthermore, various interference factors in the space environment can lead to fluctuations in the connection quality of communication links, thus constellation networks exhibit significant intermittent characteristics. In addition, onboard processing and storage resources are relatively limited, restricting resources available for topology updates, state interactions, and route calculations. This makes improving the efficiency and reliability of system route updates while ensuring communication quality a pressing issue.

[0003] Given the complex environment described above, the traditional OSPF protocol, which relies on network-wide flooding updates, struggles to adapt to frequent dynamic topology changes between satellites (typically occurring on a minute-by-minute basis). Routing algorithms need to possess both real-time network topology awareness and load balancing capabilities. Therefore, it is necessary to research dynamic routing methods suitable for hybrid orbital constellations to achieve rapid route state convergence and reduced route management overhead. Summary of the Invention

[0004] The technical problem this invention aims to solve is that in hybrid orbital constellation networks, the satellite network topology changes dynamically due to high-speed operation, inter-satellite links are intermittent due to satellite positions and the space environment, and onboard resources available for routing signaling interaction and state updates are limited. Traditional OSPF protocols based on network-wide flooding updates struggle to adapt to minute-level dynamic topology changes and lack the ability to load balance under resource-constrained conditions.

[0005] The objective of this invention is achieved through the following technical solutions: A dynamic routing method for hybrid orbit constellations based on improved OSPF is proposed. This method analyzes the characteristics of topology changes in different regions of the hybrid orbit constellation and divides the constellation network into a less dynamic backbone area and a more dynamic access area. Furthermore, to further reduce routing overhead, the access area is divided into multiple access sub-areas. A static routing protocol is used between the backbone area and each access sub-area, while the OSPF dynamic routing protocol is used within each access sub-area. This reduces global updates triggered by topology changes to localized updates within the access area, achieving minute-level rapid awareness of network topology status while reducing overall network routing update overhead.

[0006] In this invention, the high-orbit constellations (such as GEO constellations, or GEO / MEO orbit constellations in a GEO / MEO-LEO hybrid constellation) are defined as the backbone area, and the low-orbit constellations (such as LEO constellations, or MEO orbit constellations in a MEO-GEO hybrid constellation) are defined as the access area. The access area can be further divided into several access sub-areas based on the constellation's orbital distribution. In a single routing data packet transmission process, the satellite that generates the data packet is defined as the source satellite, the satellite that receives the data packet as the destination satellite, and the satellite that only forwards the data packet during the process as the intermediate satellite. Normal operation is defined as the network operating normally without node failures, link terminations, link degradation, or other abnormalities; failures are defined as the occurrence of the aforementioned faults. It is assumed that the ground station, backbone area, and access area each have network management functions, collectively referred to as the network controller.

[0007] Under normal circumstances, a hybrid orbital constellation dynamic routing method based on improved OSPF specifically includes the following: S1. During the initial network construction phase, generate and upload the backbone area static routing table, the access sub-area routing table, the access sub-area static routing table, and the backbone area-access sub-area routing table.

[0008] S11. Based on the topology of the hybrid track, the access area nodes are divided into several access sub-areas according to their track distribution.

[0009] S12. The terrestrial network controller, based on the topology settings, designates the master node in each access sub-area as the gateway node for data packets to interact between access sub-areas, backbone areas, and access sub-areas.

[0010] S13. Based on the topology settings, the ground network controller generates the initial state of the backbone area static routing table, the access sub-area routing table, the access sub-area static routing table, and the backbone area-access sub-area routing table, and uploads the routing tables to the backbone area network controller and the access area network controller.

[0011] S14. After receiving the routing table, the backbone and access network nodes complete the inter-node link establishment based on the initial topology information.

[0012] S2. The backbone network controller maintains the static routing table. It periodically updates the backbone static routing table, the access sub-interval static routing table, and the backbone-access sub-interval routing table, and synchronizes the updates to the access area and ground network controllers.

[0013] S21. Set the static routing table update time in the backbone network controller, and the backbone network controller generates new inter-satellite connection relationships based on the pre-stored satellite topology update table; S22. The backbone network controller calculates the propagation delay between backbone and access area nodes based on pre-stored orbit and other ephemeris information. S23. Generate a new static routing table for the backbone area based on the inter-satellite connection relationship and propagation delay information. Use propagation delay as the link cost and calculate the static routing table for the access sub-interval and the backbone area-access sub-interval routing table using the shortest path algorithm. After S24 and S23 generate new routing tables, the backbone network controller will synchronize the routing update information to the access area network controller and the ground network controller.

[0014] S3. The access area network controller maintains and updates the static routing table within the access sub-area.

[0015] S31. The access area network controller generates a directed connectivity graph within the area, using propagation delay as the link cost. S32. The access area network controller dynamically calculates the routing table within the access sub-area based on the shortest path algorithm, updates it, and stores it locally.

[0016] S4. When there is a data packet transmission requirement in the network, each node performs a corresponding routing process based on the positional relationship between the source and destination satellites of the data packet. The routing process is as follows: S41. When the source satellite and the destination satellite are in the same access sub-area, the access sub-area routing table is used to perform the access sub-area routing process. S42. When the source satellite and the destination satellite are in the access area but not in the same access sub-area, the access area routing process is performed using the routing table within the access sub-area and the static routing table between access sub-areas. S43. When the source satellite and the destination satellite are not on the same layer, the cross-layer routing process is performed using the routing table within the access sub-area, the static routing table between access sub-areas, the routing table between the backbone area and the access sub-area, and the static routing table of the backbone area.

[0017] In fault conditions, a hybrid orbital constellation dynamic routing method based on improved OSPF is proposed, which includes the following: S1. During the initial network construction phase, generate and upload the backbone area static routing table, the access sub-area routing table, the access sub-area static routing table, and the backbone area-access sub-area routing table.

[0018] S11. Based on the topology of the hybrid track, the access area nodes are divided into several access sub-areas according to their track distribution.

[0019] S12. The terrestrial network controller, based on the topology settings, designates the master node in each access sub-area as the gateway node for data packets to interact between access sub-areas, backbone areas, and access sub-areas.

[0020] S13. Based on the topology settings, the ground network controller generates the initial state of the backbone area static routing table, the access sub-area routing table, the access sub-area static routing table, and the backbone area-access sub-area routing table, and uploads the routing tables to the backbone area network controller and the access area network controller.

[0021] S14. After receiving the routing table, the backbone and access network nodes complete the inter-node link establishment based on the initial topology information.

[0022] S2. The access area network node synchronizes the fault information to the backbone area network node, performs fault repair, and synchronizes the corresponding situation to the ground network controller.

[0023] S21. Satellite nodes in the access area continuously exchange service data via inter-satellite links. When the inter-satellite link fails to exchange data for a certain time threshold, an inter-satellite status confirmation packet is sent to determine whether the inter-satellite link is functioning correctly. S22. If no response is received after sending an inter-satellite status acknowledgment packet within a certain time threshold, it is determined to be a link failure. The access area network controller will then report the link failure status to the backbone area network controller. S23. After receiving the link failure information uploaded by the access area, the backbone network controller corrects the connection relationship through network management data packets. The updated connection relationship is then sent to the access area and the ground network controller.

[0024] S3. The access area network controller updates the routing table based on the link congestion situation within the access sub-area; S31. Each satellite within the access area determines the link congestion level based on the occupancy status of the inter-satellite transmission queue. When the congestion level changes, it sends queue information packets to other satellites within the same sub-area. S32. After receiving the queue information packet, other satellite nodes in the sub-area estimate the queuing delay based on the link congestion status and send the estimation result to the access area network controller. S33. The access area network controller generates a directed connected graph within the area, and uses the sum of propagation delay and queuing delay as the link cost. S34. The access area network controller dynamically calculates the static routing table between access sub-intervals based on the shortest path algorithm, updates it, and stores it locally. S4. When there is a data packet transmission requirement in the network, each node performs a corresponding routing process based on the positional relationship between the source and destination satellites of the data packet. The routing process is as follows: S41. When the source satellite and the destination satellite are in the same access sub-area, the access sub-area routing table is used to perform the access sub-area routing process. S42. When the source satellite and the destination satellite are in the access area but not in the same access sub-area, the access area routing process is performed using the routing table within the access sub-area and the static routing table between access sub-areas. S43. When the source satellite and the destination satellite are not on the same layer, the cross-layer routing process is performed using the routing table within the access sub-area, the static routing table between access sub-areas, the routing table between the backbone area and the access sub-area, and the static routing table of the backbone area.

[0025] Compared with the prior art, the present invention has the following advantages: (1) This invention proposes a dynamic routing method for hybrid orbit constellation networks based on an improved OSPF. It utilizes the characteristics of hybrid orbit topology changes, employing static routing tables in the backbone area with a relatively fixed topology, while dividing the access area with significant topology changes into multiple sub-areas. Static routing is used between sub-areas, and dynamic routing is used within sub-areas. This invention resolves the contradiction between rapid changes in satellite network topology and the overall network routing convergence speed through a coupled design of physical and logical partitioning. Topology changes trigger local updates, reducing the global dynamic routing range by more than 70%.

[0026] (2) By dividing the system into backbone and access areas, static routes in the backbone area and static routes between access sub-areas are isolated from dynamic routes within the access sub-areas. Routing signaling interactions mainly occur within the access sub-areas, reducing network-wide flooding of link status announcements. For a constellation of 300 satellites, this method reduces control traffic by 48.1% compared to traditional OSPF, achieving a reduction in inter-satellite resource occupancy and demonstrating high practical value.

[0027] (3) Compared with the traditional OSPF dynamic routing protocol applied across the entire network, this invention can support seamless expansion of larger constellations. Adding new orbital planes only requires local configuration. For a constellation with n nodes and k partitions, the routing table size is reduced from O(n^2) to O(n^2). 2 The size of OSPF is reduced to O(k), thus avoiding the scalability bottleneck of traditional OSPF.

[0028] (4) Through the autonomous architecture of the partition, the present invention can realize the overall fault isolation of the constellation. Most of the routing updates caused by node failure and link failure only occur in the access sub-area. The impact range of single point failure is reduced by 90%, and local topology changes will not cause the whole network to oscillate.

[0029] (5) The method of the present invention utilizes the relative stability of the topology of high-orbit satellites in a hybrid orbit constellation to solidify the backbone routing and reduce the computational load of high-orbit nodes. Attached Figure Description

[0030] Figure 1 This is a system block diagram in an embodiment of the present invention.

[0031] Figure 2 This is a flowchart of the routing protocol in this invention.

[0032] Figure 3 This is a flowchart of the shortest path algorithm.

[0033] Figure 4 This is the format for inter-satellite status confirmation packets.

[0034] Figure 5 This is a network management data packet format.

[0035] Figure 6 This is the format for queue information packets.

[0036] Figure 7 This is a flowchart of the data packet routing process within the access sub-area.

[0037] Figure 8 This is a flowchart of the data packet routing process within the access area.

[0038] Figure 9 This is a flowchart of the cross-layer packet routing process. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0040] This invention proposes a dynamic routing method based on an improved OSPF hybrid orbit constellation. Leveraging the wide coverage of high-orbit satellites, it manages the routing and forwarding process of low-orbit satellites in segments, employing a combined static and dynamic routing approach. Network status maintenance occurs only within the access sub-cell, thereby reducing overall network routing overhead. The specific implementation details are described below with reference to the accompanying drawings.

[0041] The system model used in this embodiment is as follows: Figure 1 As shown, the routing protocol flowchart used in this embodiment is as follows. Figure 2 As shown.

[0042] Step 1: In the initial network construction phase, generate and upload the backbone area static routing table, the access sub-area routing table, the access sub-area static routing table, and the backbone-access inter-area routing table; 1) This embodiment takes a hybrid medium-low orbit constellation as an example. The medium orbit constellation is divided into a backbone area, and the low orbit constellation is divided into an access area. Based on the orbital distribution of the low orbit satellites, it is further divided into several access sub-areas.

[0043] 2) The ground network controller designates a number of low-orbit satellites as master nodes in each access sub-area based on the topology settings.

[0044] 3) Based on the topology settings, the ground network controller generates static routing tables within the medium orbit constellation, static routing tables for each sub-interval of the low orbit constellation, routing tables for the medium-low orbit interval, and routing tables within the low orbit sub-interval, and uploads the routing tables to the medium orbit network controller and the low orbit network controller.

[0045] 4) After receiving the routing table, the mid-orbit and low-orbit network nodes complete the inter-satellite link establishment based on the initial topology information.

[0046] Step Two: First Operating Scenario: Under normal circumstances, the medium-Earth orbit network controller completes the maintenance of the static routing table. It periodically updates the static routing tables within the medium-Earth orbit constellation, between different areas of the low-Earth orbit constellation, and between medium- and low-Earth orbits, and synchronizes the updates to the low-Earth orbit network controller and the ground network controller. 1-1) Set the static routing table to be updated periodically every 30 minutes. That is, every 30 minutes, the intermediate-orbit network controller generates new inter-satellite connections based on the pre-stored topology update table; 1-2) The intermediate orbit network controller calculates the propagation delay between intermediate orbit satellites and low orbit master nodes within the intermediate orbit constellation based on the pre-stored orbital ephemeris information; 1-3) The medium-orbit network controller generates a new routing table within the medium-orbit constellation, using propagation delay as the link cost, and calculates the static routing table for the low-orbit access sub-interval and the medium-orbit-low-orbit interval routing table using the shortest path algorithm. The calculation process is as follows: Figure 3 As shown; 1-4) After generating the new routing table, the intermediate orbit network controller will synchronize the routing update information to the low orbit network controller and the ground network controller.

[0047] The second operating condition: In the event of a fault, the low-orbit network node will synchronize the fault information to the backbone network node, carry out fault repair, and synchronize the corresponding situation to the ground network controller.

[0048] 2-1) Low-Earth orbit satellite nodes continuously exchange service data via inter-satellite links. If no data is exchanged via the inter-satellite link for more than one minute, an inter-satellite status acknowledgment packet is sent to determine whether the inter-satellite link is functioning correctly. The data format of the inter-satellite status acknowledgment packet is as follows: Figure 4 As shown; 2-2) If no response is received after the timeout period following the transmission of the inter-satellite status confirmation packet, it is determined to be a link failure. The Low Earth Orbit Network Controller (LEO) reports the link failure status to the Medium Earth Orbit Network Controller (MEO). 2-3) After receiving link failure information from a low-Earth orbit satellite, the medium-Earth orbit network controller corrects the connection relationship through network management data packets. The format of the network management data packets is as follows: Figure 5 As shown. The updated connectivity relationships are then sent to the low-Earth orbit satellite network controller and the ground network controller.

[0049] Step 3: First operating condition: Under normal circumstances, the low-Earth orbit satellite network controller maintains and updates the routing tables in each low-Earth orbit access sub-area; 1-1) The low-orbit network controller generates a directed connected graph within the corresponding sub-region, using propagation delay as the link cost; 1-2) The LOR network controller dynamically calculates the routing table within the LOR access sub-cell based on the shortest path algorithm, updates it, and stores it locally. The shortest path algorithm process is as follows: Figure 3 As shown.

[0050] The second operating condition: In the event of a fault, the low-orbit network controller updates the routing table based on the link congestion situation within the access sub-area; 2-1) Low-Earth orbit (LEO) satellites determine the link congestion level based on the occupancy status of the inter-satellite transmission queue. Upon detecting a change in congestion level, they send queue information packets to other LEO satellites within the sub-area. The format of the queue information packet is as follows: Figure 6 As shown; 2-2) After receiving the queue information packet, other satellite nodes in the sub-area estimate the queuing delay based on the link congestion status and send the estimation results to the low-Earth orbit network controller. 2-3) The low-orbit network controller generates a directed connected graph within the region, and uses the sum of propagation delay and queuing delay as the link cost; 2-4) The low-orbit network controller dynamically calculates the routing table within the access sub-area based on the shortest path algorithm, updates it, and stores it locally.

[0051] Step 4: When there is a need to send data packets in the network, each node performs the corresponding routing process based on the positional relationship between the source satellite and the destination satellite of the data packet.

[0052] 1) When both the source and destination satellites are low-Earth orbit satellites and are within the same sub-region, the data packet routing process is as follows: Figure 7 As shown; 2) When both the source and destination satellites are low-Earth orbit satellites but not in the same sub-region, the data packet routing process is as follows: Figure 8 As shown; 3) When the source satellite is a medium-Earth orbit satellite and the destination satellite is a low-Earth orbit satellite, the data packet routing process is as follows: Figure 9 As shown.

[0053] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0054] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A dynamic routing method for hybrid orbital constellations based on an improved OSPF, characterized in that, include: S1. During the initial network construction phase, generate and upload the backbone area static routing table, the access sub-area routing table, the access sub-area static routing table, and the backbone area-access sub-area routing table. S2. The backbone network controller maintains the static routing table; it regularly updates the backbone static routing table, the access sub-interval static routing table, and the backbone-access sub-interval routing table, and synchronizes the updates to the access area and ground network controllers. S3. The access area network controller maintains and updates the static routing table within the access sub-area; S4. When there is a need to send data packets in the network, each node performs the corresponding routing process according to the positional relationship between the source satellite and the destination satellite of the data packet.

2. The hybrid orbital constellation dynamic routing method according to claim 1, characterized in that, S1 includes: S11. Based on the topology of the hybrid track, the access area is divided into several access sub-areas according to the track distribution of the access area nodes. S12. The terrestrial network controller, based on the topology settings, designates the master node in each access sub-area as the gateway node for data packets to interact between access sub-areas, the backbone area, and the access sub-areas. S13. Based on the topology settings, the ground network controller generates the initial state of the backbone area static routing table, the access sub-area routing table, the access sub-area static routing table, and the backbone area-access sub-area routing table, and uploads the routing tables to the backbone area network controller and the access area network controller. S14. After receiving the routing table, the backbone and access network nodes complete the inter-node link establishment based on the initial topology information.

3. The hybrid orbital constellation dynamic routing method according to claim 1, characterized in that, S2 include: S21. Set the static routing table update time in the backbone network controller, and the backbone network controller generates new inter-satellite connection relationships based on the pre-stored satellite topology update table; S22. The backbone network controller calculates the propagation delay between backbone and access area nodes based on pre-stored orbit and other ephemeris information. S23. Generate a new static routing table for the backbone area based on the inter-satellite connection relationship and propagation delay information. Use propagation delay as the link cost and calculate the static routing table for the access sub-interval and the backbone area-access sub-interval routing table using the shortest path algorithm. After S24 and S23 generate new routing tables, the backbone network controller will synchronize the routing update information to the access area network controller and the ground network controller.

4. The hybrid orbital constellation dynamic routing method according to claim 1, characterized in that, S3 include: S31. The access area network controller generates a directed connectivity graph within the area, using propagation delay as the link cost. S32. The access area network controller dynamically calculates the routing table within the access sub-area based on the shortest path algorithm, updates it, and stores it locally.

5. The hybrid orbital constellation dynamic routing method according to claim 1, characterized in that, In S4, the routing process is as follows: S41. When the source satellite and the destination satellite are in the same access sub-area, the access sub-area routing table is used to perform the access sub-area routing process. S42. When the source satellite and the destination satellite are in the access area but not in the same access sub-area, the access area routing process is performed using the routing table within the access sub-area and the static routing table between access sub-areas. S43. When the source satellite and the destination satellite are not on the same layer, the cross-layer routing process is performed using the routing table within the access sub-area, the static routing table between access sub-areas, the routing table between the backbone area and the access sub-area, and the static routing table of the backbone area.

6. A dynamic routing method for hybrid orbital constellations based on an improved OSPF, characterized in that, In fault conditions, including: S1. During the initial network construction phase, generate and upload the backbone area static routing table, the access sub-area routing table, the access sub-area static routing table, and the backbone area-access sub-area routing table. S2. The access area network node synchronizes the fault information to the backbone area network node, performs fault repair, and synchronizes the corresponding situation to the ground network controller. S3. The access area network controller updates the routing table based on the link congestion situation within the access sub-area; S4. When there is a need to send data packets in the network, each node performs the corresponding routing process according to the positional relationship between the source satellite and the destination satellite of the data packet.

7. The hybrid orbital constellation dynamic routing method according to claim 6, characterized in that, S1 includes: S11. Based on the topology of the hybrid track, the access area is divided into several access sub-areas according to the track distribution of the access area nodes. S12. The terrestrial network controller, based on the topology settings, designates the master node in each access sub-area as the gateway node for data packets to interact between access sub-areas, the backbone area, and the access sub-areas. S13. Based on the topology settings, the ground network controller generates the initial state of the backbone area static routing table, the access sub-area routing table, the access sub-area static routing table, and the backbone area-access sub-area routing table, and uploads the routing tables to the backbone area network controller and the access area network controller. S14. After receiving the routing table, the backbone and access network nodes complete the inter-node link establishment based on the initial topology information.

8. The hybrid orbital constellation dynamic routing method according to claim 6, characterized in that, S2 include: S21. Satellite nodes in the access area continuously exchange service data through inter-satellite links; When the inter-satellite link fails to exchange data for a certain time threshold, an inter-satellite status confirmation packet is sent to determine whether the inter-satellite link is normal. S22. If no response is received after sending an inter-satellite status confirmation packet for a certain period of time, it is determined to be a link failure; the access area network controller will report the link failure status to the backbone area network controller. S23. After receiving the link failure information uploaded by the access area, the backbone network controller corrects the connection relationship through network management data packets and sends the updated connection relationship to the access area and the ground network controller.

9. The hybrid orbital constellation dynamic routing method according to claim 6, characterized in that, S3 include: S31. Each satellite in the access area determines the congestion level of the link based on the occupancy status of the inter-satellite transmission queue; when the congestion level changes, it sends queue information packets to other satellites in the same sub-area. S32. After receiving the queue information packet, other satellite nodes in the sub-area estimate the queuing delay based on the link congestion status and send the estimation result to the access area network controller. S33. The access area network controller generates a directed connected graph within the area, and uses the sum of propagation delay and queuing delay as the link cost. S34. The access area network controller dynamically calculates the static routing table of the access sub-interval according to the shortest path algorithm, updates it and stores it locally.

10. The hybrid orbital constellation dynamic routing method according to claim 6, characterized in that, In S4, the routing process is as follows: S41. When the source satellite and the destination satellite are in the same access sub-area, the access sub-area routing table is used to perform the access sub-area routing process. S42. When the source satellite and the destination satellite are in the access area but not in the same access sub-area, the access area routing process is performed using the routing table within the access sub-area and the static routing table between access sub-areas. S43. When the source satellite and the destination satellite are not on the same layer, the cross-layer routing process is performed using the routing table within the access sub-area, the static routing table between access sub-areas, the routing table between the backbone area and the access sub-area, and the static routing table of the backbone area.

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