A on-board tag forwarding method based on time slices

Abstract

The present invention discloses a method for on-board label forwarding based on time slices. The ground control center pre-computes the LSP label forwarding paths for different time slices and reserves on-board resources. Multiple LSP label forwarding tables for different time slices are respectively stored in each satellite node. When performing service forwarding on-board, the relevant entries in the forwarding table are queried according to the label field content of the data packet in the current time slice, and the data packet is forwarded on the pre-established LSP label forwarding path. The method of the present invention can provide QoS guarantee for multiple types of connection-oriented services, reduce the on-board computing complexity, well adapt to the highly dynamic nature of the satellite-ground network topology, and reduce the routing signaling overhead.

Description

Technical Field

[0001] The present invention belongs to the field of communication technologies, and particularly relates to a method for on-satellite label forwarding based on time slices. Background Art

[0002] Satellite communication network systems have the advantages of wide coverage, flexible networking, and high communication quality, and have gradually become the current mainstream communication method. Using satellite networks is convenient for achieving global coverage, and is regarded as the most eye-catching new star in the future 6G communication era, with broad application prospects and great development potential. With the application and development of satellite network technologies, low Earth orbit (LEO) satellite networks have the advantages of short propagation delay, low transmission loss, low launch cost, etc., and have gradually become the research focus of various countries in the satellite field. Many countries have announced new plans for building low-orbit constellations.

[0003] In LEO satellite networks, users have relatively high service requirements for end-to-end delay, packet loss rate, bandwidth resources, etc. The services supported by the network are gradually developing in the direction of multi-demand and multi-type services from traditional simple data services. LEO satellite networks are composed of inter-satellite links between the same orbit or adjacent orbits, and their network topology and satellite-ground topology have a high degree of dynamic variability. However, compared with terrestrial mobile ad-hoc networks, the movement of satellites in the LEO satellite constellation has regularity and predictability. Utilizing this characteristic can improve the resource utilization rate and capacity of satellite networks.

[0004] Due to the influence of geographical factors, economic level, and population density, the distribution of users and traffic in satellite networks is not uniform, increasing the uneven distribution of traffic and services in the network, and making it more difficult to ensure the quality of service (QoS) of satellite services. In addition, with the rapid development of multimedia services, the services supported by the network are gradually developing in the direction of multi-demand and multi-type services from traditional simple data services. Therefore, the problem of guaranteeing QoS services in satellite networks is worthy of in-depth research. For this research, the existing proposed solutions are as follows:

[0005] Jiang Wenjuan et al. proposed a traffic classification routing algorithm (Traffic Classification Routing, abbreviated as TCR): This algorithm models the global traffic distribution and divides the services in the network into three categories, each with different QoS metrics; this algorithm calculates different link costs for each service according to its QoS metrics, and performs congestion control by calculating the link blocking probability threshold; the TCR algorithm to a certain extent guarantees the QoS requirements of multiple services and can perform congestion control, but this algorithm requires each LEO satellite to have the ability to sense the states of all links in the network and strong real-time computing capabilities; Dong Y et al. proposed a QoS dynamic routing algorithm based on network status adaptation (Status Adaptive QoS Dynamic Routing, abbreviated as SADR): The SADR algorithm uses the ant colony optimization algorithm to perform dynamic path search and dynamic routing table update. In the case of changes in topology and network status, SADR can achieve better QoS guarantee; however, the on-board computing complexity is also relatively high, and the signaling overhead brought by the ant colony algorithm is large; Donner et al. proposed to apply the MPLS idea to the LEO satellite network and divide the related MPLS functions. According to the routing and management label switching path (Label Switch Path, abbreviated as LSP), there are three MPLS satellite schemes, namely distributed routing and LSP management, centralized routing distributed LSP management, and centralized routing and LSP management. However, only the network architecture and preliminary qualitative analysis are proposed in the article, and issues such as signaling overhead, frequent establishment and forwarding process of LSP are not considered.

[0006] However, the above existing solutions have the following problems:

[0007] First, it cannot adapt well to the topological dynamics of the LEO satellite network, resulting in large signaling and computing overhead;

[0008] Second, it is only applicable to the QoS requirements of a single type or demand, and it is difficult to provide good QoS guarantee to a certain extent;

[0009] Third, it has high requirements for the computing power and sensing ability of satellites, and the computing complexity of the algorithm is high. Summary of the Invention

[0010] In order to solve the above problems existing in the prior art, the present invention provides an on-board label forwarding method based on time slices. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0011] An embodiment of the present invention provides an on-board label forwarding method based on time slices, including the following steps:

[0012] Step (1): Adopt an inclined orbit LEO satellite constellation. Under normal operation, the satellite topology is stable and unchanged. Adopt the idea of a fixed earth coverage area, divide the ground area into multiple coverage areas, and within a certain period of time, each coverage area is served by a LEO satellite constellation.

[0013] Step (2): According to the coverage areas divided in step (1), as the satellite moves and the earth rotates, the satellite will switch from the current coverage area to the next coverage area. According to the switching time of the satellite between the coverage areas, divide it into multiple time slices.

[0014] Step (3): The ground control center determines the mapping relationship between the coverage area and the satellite according to the virtual topology of the satellite network corresponding to each time slice. At the same time, each satellite node uses the shortest path algorithm to calculate the default routing table to the remaining nodes in the virtual topology of the satellite network, and this default routing table is used for connectionless forwarding and link failure handling.

[0015] Step (4): The ground control center calculates and establishes multiple LSP paths between the coverage areas of each time slice according to the global regional traffic distribution model, the virtual topology of the satellite network, as well as the service type and QoS requirements.

[0016] Step (5): The ground control center generates the relevant table entries corresponding to each time slice according to the calculated LSP paths. These relevant table entries include the FEC label mapping table generated by the ground control center for users, as well as the LSP label forwarding table and the coverage area mapping table generated by the ground control center for the LEO satellite constellation.

[0017] Step (6): If it reaches the upload time of the LSP label forwarding table or the default routing table calculation and update is triggered due to the change of the virtual topology of the satellite network, the ground control center uploads the newly generated LSP label forwarding table to the satellite node, and sends the newly generated FEC label mapping table and the coverage area mapping table to the terminal.

[0018] Step (7): When the user source terminal sends a service, it knows whether to use the label forwarding method according to its FEC label mapping table. If so, query the corresponding label of the service according to the FEC label mapping table, construct a data packet and add the corresponding label field, and send it to the satellite node serving the current coverage area.

[0019] Step (8): After receiving the data packet, the satellite node queries the label forwarding field using different LSP label forwarding tables in each time slice, and selects the corresponding forwarding mechanism to forward the packet.

[0020] Step (9): If there is a link failure or a satellite node failure in the virtual topology of the satellite network, the current fault information is informed to the ground control center, and the processes of steps (3) to (6) are executed, and the normal service sending process is continued; if all satellite nodes in the virtual topology of the satellite network are operating normally, the satellite still periodically counts the network status and summarizes it to the ground control center;

[0021] Step (10): After the destination terminal receives the data packet, it removes the packet header, extracts the payload field, obtains the transmitted service, and sends the service to the upper layer for processing.

[0022] In an embodiment of the present invention, the implementation process of dividing multiple coverage areas in step (1) is as follows:

[0023] Adopting the geostationary footprint mode, the satellite controls its beam and provides services for a certain coverage area for a period of time.

[0024] In an embodiment of the present invention, the implementation process of dividing time slices in step (2) is as follows:

[0025] Step (2a): According to the selected satellite, calculate the handover time interval within its orbit, and the calculation formula is as follows:

[0026]

[0027] where t intra is the handover time interval within the orbit, T is the satellite orbit period, and SATE_PER_ORBIT is the number of satellites on each orbit;

[0028] Step (2b): Calculate the handover time interval between orbits, and the calculation formula is as follows:

[0029]

[0030] where t inter is the handover time interval between orbits, φ is the longitude span angle of the coverage area, and ω earth is the angular velocity of the earth's rotation;

[0031] Step (2c): Adopting the synchronous handover method, when one satellite switches to the next coverage area, all other satellites must perform the same action; the ground control center calculates the handover time of the satellite according to the handover time interval within the orbit and the handover time interval between orbits obtained in steps (2a) to (2b), and divides multiple time slices according to the handover time; among them, the satellite-ground network topology relationship within each time slice is regarded as static and unchanged.

[0032] In an embodiment of the present invention, the implementation process of the ground control center determining the virtual topology of the satellite network in step (3) is as follows:

[0033] Step (3a-1): Let n be the number of satellite nodes in the virtual topology of the satellite network. Different time slices are denoted as t1, t2,..., t k ,..., t m , t k is the k-th time slice, m is the number of time slices. For the k-th time slice t k , represent the virtual topology of the satellite network with a directed graph ; where, V = {v1, v2,..., v n} is the set of satellite nodes in the virtual topology of the satellite network, n represents the number of satellite nodes in the virtual topology of the satellite network, is the set of available inter-satellite links;

[0034] Step (3b-1): Let e ij be the inter-satellite link from the i-th satellite to the j-th satellite. When e ij is an available inter-satellite link, its value is 1, otherwise, its value is 0, that is

[0035] Step (3c-1): Calculate the adjacency matrix of the directed graph ij according to e to obtain the virtual topology of the satellite network for the k-th time slice t ; k of the satellite network;

[0036] Step (3d-1): Repeat Step (3a-1) to Step (3c-1) m times to obtain the virtual topologies of the satellite network for all time slices.

[0037] In an embodiment of the present invention, in Step (3), the mapping relationship between the satellite and the ground coverage area is determined according to the virtual topology of the satellite network corresponding to each time slice, and the implementation process is as follows:

[0038] Let n be the number of satellite nodes in the virtual topology of the satellite network. According to the number of orbits and the number of satellites on each orbit in the virtual topology of the satellite network, the ground is evenly divided into different ground coverage areas according to longitude and latitude: R = {r1, r2,..., r n}, r i represents the ground coverage area corresponding to the i-th satellite node in the virtual topology of the satellite network;

[0039] According to the longitude and latitude of the satellite's movement in each time slice, determine the ground coverage area mapped by it in each time slice to obtain the mapping relationship between the satellite and the ground coverage area for each time slice.

[0040] In an embodiment of the present invention, the implementation process of each satellite node in step (3) calculating the default routing table to the remaining satellite nodes in the virtual topology of the satellite network using the shortest path algorithm is as follows:

[0041] Step (3a-2): Each satellite node statistically analyzes the link state information and conducts interactions, and defines the real-time link cost metric. The calculation formula is as follows:

[0042] L cost (t) = T prop +T queue (t);

[0043] Wherein, L c o st (t) is the real-time link cost metric at time t, T prop is the propagation delay of the link, and T queue (t) is the queuing delay of the link at time t;

[0044] Step (3b-2): Use the real-time link cost metric as the path weight;

[0045] Step (3c-2): Select a satellite node s in the virtual topology of the satellite network, and establish two sets for this satellite node s: a source node set A and a destination node set B;

[0046] Step (3d-2): Initially, the source node set A only contains the satellite node s, and the destination node set B contains other satellite nodes in the virtual topology of the satellite network except the satellite node s;

[0047] Step (3e-2): Select the satellite node k with the smallest path weight from the destination node set B, add this satellite node k to the source node set A, and at the same time, remove the satellite node k from the destination node set B;

[0048] Step (3f-2): Update the path weights of each satellite node in the destination node set B to the satellite node s, that is, for the case of (s,v) > (s,k) + (k,v), update (s,v) to (s,k) + (k,v), where (s,v) is the path weight from the satellite node s to the satellite node v, (s,k) is the path weight from the satellite node s to the satellite node k, and (k,v) is the path weight from the satellite node k to the satellite node v;

[0049] Step (3g-2): Repeat steps (3e-2) to (3f-2) until all satellite nodes in the virtual topology of the satellite network are traversed to obtain the shortest paths from the satellite node s to other satellite nodes in the virtual topology of the satellite network;

[0050] Step (3h-2): Delete the satellite nodes in the shortest path from the destination node set B, and re-execute steps (3e-2) to (3g-2) to obtain an alternative path in the virtual topology of the satellite network;

[0051] Step (3i-2): Perform the process of steps (3c-2) to (3h-2) for all satellite nodes in the virtual topology of the satellite network to obtain the shortest paths and alternative paths from all satellite nodes in the virtual topology of the satellite network to other satellite nodes, and generate and store a default routing table at the corresponding satellite nodes according to the shortest paths and alternative paths.

[0052] In an embodiment of the present invention, when calculating the LSP path in step (4), the services are classified according to QoS requirements, and each type of service uses the Bellman-Ford or genetic algorithm to calculate the LSP path that meets the QoS requirements.

[0053] In an embodiment of the present invention, the process of the ground control center generating the relevant table entries corresponding to each time slice according to the calculated LSP path in step (5) is as follows:

[0054] Step (5a): The ground control center generates an FEC label mapping table for the user; the FEC label mapping table is the mapping relationship between the multi-tuple and the label; and then it is sent to the terminals in each coverage area; wherein, the multi-tuple includes the source terminal, the destination terminal, the QoS requirement, and the protocol type; the label is globally and uniformly assigned by the ground control center and has the uniqueness of assignment, and the uniqueness of label assignment means that the same "input port + input label" should not appear in multiple satellite nodes;

[0055] Step (5b): The ground control center generates an LSP label forwarding table and a coverage area mapping table for the LEO satellite; then it annotates the LSP label forwarding table of each time slice, as well as the FEC label mapping table and the coverage area mapping table to the satellite nodes; wherein, the LSP label forwarding table is the mapping relationship from "input label + input port" to "output port"; the coverage area mapping table is the mapping relationship between the satellite node and the coverage area.

[0056] In an embodiment of the present invention, the data packet constructed in step (7) includes the destination coverage area, the source coverage area, the destination terminal identifier, and the source terminal identifier; wherein, the destination coverage area identifier is used to query the identifier of the destination satellite during connectionless forwarding, and the destination terminal identifier is used to send to the destination terminal after reaching the destination satellite.

[0057] In an embodiment of the present invention, the process of querying the label forwarding field using different LSP label forwarding tables in each time slice and selecting the corresponding forwarding mechanism for packet forwarding in step (8) is as follows:

[0058] Step (8a): If the label forwarding field adopts the label forwarding method, query its LSP label forwarding table to obtain the corresponding output port, and forward it to the next-hop satellite;

[0059] Step (8b): If the label forwarding field does not adopt the label forwarding method, query the default routing table and the coverage area mapping table, and forward it to the next-hop satellite;

[0060] Step (8c): If the current satellite is the destination satellite, forward the service to the destination terminal.

[0061] Advantages of the present invention:

[0062] The on-satellite label forwarding method based on time slices proposed by the present invention adopts the idea of time slices, uses the ground fixed coverage area and satellite handover time to divide time slices, and regards the topological structure of the space-ground network as fixed and unchanged within each time slice, converting the dynamic topology of the space-ground network into a static topology, which is convenient for routing calculation. Therefore, it can well adapt to the topological dynamics of the space-ground network; since the present invention uses the ground control center to perform centralized offline calculation of the LSP paths between each pair of coverage areas and upload them according to time slices, there is no need for satellite nodes to calculate the routing paths of label forwarding, thus reducing the complexity of on-satellite calculation; during the on-satellite label switching process, satellite nodes only need to query the label field of the data packet and the label forwarding table, reducing the complexity of on-satellite forwarding processing; when the ground control center calculates the label forwarding path offline, it calculates the routing through the link state feedback by the satellite and the global regional traffic distribution model, so that the planned path routing can better guarantee user QoS and improve the utilization rate of inter-satellite links; when the ground control center calculates the label forwarding path offline, it establishes coarse-grained pipelines between each pair of coverage areas, rather than calculating an LSP for each service. Therefore, multiple services can use the same LSP for transmission, thus reducing the complexity of LSP establishment and signaling overhead. The survival time of the LSP is the same as that of the time slice. As the current time slice ends, the valid LSP forwarding table of the next time slice is adopted, thus avoiding the problem of frequent establishment and removal of LSPs caused by service termination or user movement. It can be seen that the present invention pre-calculates the LSP label forwarding paths of different time slices by the ground control center and reserves on-satellite resources, saves multiple LSP label forwarding tables of different time slices at each satellite node respectively, and when forwarding services on the satellite, queries the relevant entries in the forwarding table according to the label field content of the data packet in the current time slice, and forwards the data packet on the pre-established LSP label forwarding path. This method can provide QoS guarantee for multiple types of connection-oriented services, reduce the on-satellite calculation complexity, well adapt to the high dynamics of the space-ground network topology, and reduce routing signaling overhead.

[0063] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 is a schematic diagram of a space - to - ground network system provided by an embodiment of the present invention;

[0065] Figure 2 is a schematic flowchart of a satellite - based label forwarding method based on time slots provided by an embodiment of the present invention;

[0066] Figure 3 is a schematic diagram of the division of the earth's surface coverage area provided by an embodiment of the present invention;

[0067] Figure 4 is a schematic flowchart of a terminal for constructing data packets provided by an embodiment of the present invention;

[0068] Figure 5 is a schematic diagram of the data format of the constructed data packet provided by an embodiment of the present invention;

[0069] Figure 6 is a schematic flowchart of a satellite for forwarding data packets provided by an embodiment of the present invention;

[0070] Figure 7 is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] The present invention will be further described in detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0072] Through research by the inventor, it is found that due to the influence of geographical factors, economic levels, and population density, the distribution of users and traffic in satellite networks is uneven, increasing the unevenness of traffic and services in the network, and making it more difficult to ensure the quality of service (QoS) of satellite services. In addition, with the rapid development of multimedia services, the services supported by the network are gradually shifting from traditional simple data services to multi - demand and multi - type services. Therefore, the problem of ensuring QoS services in satellite networks is worthy of in - depth research. In addition, if the idea similar to the MPLS technology is adopted and the label forwarding mechanism is applied to satellite networks, due to the high dynamicity of the space - to - ground network topology, the overhead satellite of the terminal will constantly switch, and the frequent establishment / destruction of label forwarding paths (LSPs) cannot guarantee the QoS of users and the signaling overhead is huge. However, by calculating the label forwarding path and reserving on - satellite resources in a centralized manner in advance through a ground control center, the on - satellite computational complexity can be reduced. It can be seen that the following problems should be solved

[0073] (1), Good adaptation to the dynamicity of the space - to - ground network topology

[0074] The label forwarding mechanism should be able to adapt well to the highly dynamic topology of the space-ground network, which includes two aspects. One is the topology change of the satellite network, which is caused by the disconnection of inter-satellite links when satellites enter the polar region in a near-polar orbit constellation. The other is the topology change of the space-ground network. Since LEO satellites are not geosynchronous, the coverage area of the satellites will change frequently. Therefore, the label forwarding mechanism of the on-board network needs to adapt to this characteristic to avoid adverse effects such as frequent establishment and removal of LSPs and large signaling overhead.

[0075] (2) Consider the QoS requirements of different services

[0076] With the rapid development of satellite communication network technology, the network can accommodate more types of services, and at the same time, higher service requirements are also put forward. Considering the characteristics of the LEO satellite network, such as multiple transmission service types, large data traffic, and diverse demands, it is very important to consider the effective paths of different services. Therefore, the label forwarding method should fully consider this point.

[0077] (3) Reduce the computational complexity on the satellite

[0078] Due to the relatively large electromagnetic interference and ionizing radiation in space, the limitations of technical levels and the particularity of the space environment, the volume and resources of satellites are restricted, resulting in limited on-board computing power and storage resources. When designing the label forwarding method, it should be simple and easy to implement on the satellite so that this technology can be better applied to satellite networks.

[0079] Based on the above analysis, the present invention is based on Figure 1 the space-ground network system shown, and realizes an on-board label forwarding method based on time slices. Figure 1The satellite - ground network system includes three parts: the LEO satellite network, the ground control center, and user terminals. The LEO satellite network uses an inclined - orbit LEO satellite constellation as the scenario. The LEO satellite constellation includes several satellite nodes. The satellites described hereafter are satellite nodes in the LEO satellite constellation. Inter - satellite links are established between adjacent satellites in the same orbit and between two satellites in adjacent orbits. Each satellite has at most 4 inter - satellite links, and its satellite network topology remains unchanged. In the embodiment of the present invention, the currently orbiting GlobalStar constellation configuration is selected, which includes 8 orbits, with 6 satellites on each orbit, an orbital inclination angle of 52°, can cover the area between 70° north and south latitudes, and has an operating period of 114 min. The main functions of the satellite network are to aggregate link - state information and report it to the ground control center, data forwarding, and calculating the default routing table; user terminals mainly include ground user terminals and large - scale devices, etc., which usually serve as the source and destination of services and have functions of label management and frame assembly / disassembly; the ground control center is mainly responsible for calculating label forwarding paths, uploading table entries, etc. Correspondingly, based on Figure 1 the satellite - ground network system shown, please refer to Figure 2 , the embodiment of the present invention provides a time - slice - based on - satellite label forwarding method, which specifically includes the following steps:

[0080] Step (1): Adopt an inclined - orbit LEO satellite constellation. Under normal operation, the satellite topology remains stable and unchanged; adopt the idea of an earth - fixed coverage area, divide the ground area into multiple coverage areas, and within a certain period of time, each coverage area is served by a LEO satellite constellation.

[0081] In an embodiment of the present invention, the implementation process of dividing the multiple coverage areas in step (1) is as follows: Adopt the earth - fixed footprint mode, and the satellite controls its beam to provide services for a certain coverage area within a certain period of time. Specifically:

[0082] The number of divided areas on the earth is the same as the number of satellite nodes in the LEO satellite constellation, and the area - division form is M * N, where M is the number of orbits in the LEO satellite constellation and N is the number of satellite nodes on each orbit. Each coverage area is assigned a logical number. Each coverage area has a satellite node to serve it, so there is a one - to - one mapping between satellites and coverage areas. In the embodiment of the present invention, the ground area is divided into 48 coverage areas, the longitude span of each area is 45°, the latitude span of each area is 23°, and the numbers of the divided coverage areas are Figure 3 shown.

[0083] It should be noted here that if there is a situation where the latitudes in the LEO satellite constellation configuration are difficult to be evenly divided, the number of users in high - latitude regions is relatively small, so the high - latitude regions can be appropriately divided smaller and adjusted according to the actual situation.

[0084] Step (2): According to the coverage areas divided in step (1), as the satellite moves and the Earth rotates, the satellite will switch from the current coverage area to the next one. Multiple time slices are divided based on the switching time of the satellite between coverage areas.

[0085] As Figure 3 shown, for the divided Earth-fixed coverage areas, due to the periodic motion of the satellite and the influence of the Earth's rotation, the coverage area served by the satellite will undergo the process of in-orbit switching and inter-orbit switching. Then, in an embodiment of the present invention, the implementation process of dividing the time slices in step (2) is as follows:

[0086] Step (2a): Calculate the in-orbit switching time interval for the selected satellite. The calculation formula is as follows:

[0087]

[0088] where t intra is the in-orbit switching time interval, T is the satellite orbit period, and SATE_PER_ORBIT is the number of satellites on each orbit;

[0089] Step (2b): Calculate the inter-orbit switching time interval. The calculation formula is as follows:

[0090]

[0091] where t inter is the inter-orbit switching time interval, φ is the longitude span angle of the coverage area, and ω earth is the Earth's angular velocity of rotation;

[0092] Step (2c): Adopt the synchronous switching method. When one satellite switches to the next coverage area, all other satellites must perform the same action; the ground control center calculates the switching time of the satellite based on the in-orbit switching time interval and the inter-orbit switching time interval obtained in steps (2a) to (2b), and divides multiple time slices according to the switching time; among them, the satellite-ground network topology relationship within each time slice is regarded as static and unchanged.

[0093] Assume taking the GlobalStar constellation as an example, which includes 8 orbits, with 6 satellites on each orbit, and the satellite orbit period is 114 min. Then the time for inter-orbit switching can be calculated by formula (1) in step 2(a), and the in-orbit switching time is 19 min. The calculation is

[0094] Due to the Earth's rotation, the satellite will also undergo inter-orbit switching of the coverage area. First, calculate the Earth's angular velocity of rotation Since the longitudinal span of the coverage area in the embodiments of the present invention is 45°, the time for handover between orbits is calculated as 180 min through formula (2) in step 2(b), and the calculation is

[0095]

[0096] Adopting the idea of an earth-fixed coverage area has the advantage of synchronous handover, that is, the clocks on the satellites are synchronized. Once a satellite switches to the next coverage area, all other satellites must perform the same action. Therefore, for a period of time, the satellite nodes will be fixed to serve a certain coverage area, and the space-ground network topology relationship is regarded as static and unchanged, thus simplifying the topological changes brought about by the mobility of the satellites. This method can well adapt to the topological dynamic changes of the space-ground network. According to the periodicity and predictability of satellite movement, the ground control center can calculate the satellite handover time in advance and then divide it into multiple time slices. According to steps (2a) and (2b), the time maintained by each time slice is relatively long.

[0097] Step (3): The ground control center determines the mapping relationship between the coverage area and the satellites according to the virtual topology of the satellite network corresponding to each time slice; at the same time, each satellite node uses the shortest path algorithm to calculate the default routing table to the remaining nodes in the virtual topology of the satellite network, and this default routing table is used for connectionless forwarding and link failure handling.

[0098] In an embodiment of the present invention, the implementation process of the ground control center determining the virtual topology of the satellite network in step (3) is as follows:

[0099] Step (3a-1): Let n be the number of satellite nodes in the virtual topology of the satellite network, and different time slices are denoted as t1, t2,..., t k ,..., t m , t k is the kth time slice, m is the number of time slices. For the kth time slice t k , the virtual topology of the satellite network is represented by a directed graph ; where V = {v1, v2,..., v n} is the set of satellite nodes in the virtual topology of the satellite network, n represents the number of satellite nodes in the virtual topology of the satellite network, is the set of available inter-satellite links;

[0100] Step (3b-1): Let e ij be the inter-satellite link from the ith satellite to the jth satellite. When e ij is an available inter-satellite link, its value is 1; otherwise, its value is 0, that is

[0101] Step (3c-1): According to e ijCalculating a directed graph of the adjacency matrix to obtain the virtual topology of the satellite network at the k-th time slice t k ;

[0102] Step (3d-1), repeat steps (3a-1) to (3c-1) for m times to obtain the virtual topologies of the satellite network for all time slices.

[0103] In an embodiment of the present invention, in step (3), the mapping relationship between the satellite and the ground coverage area is determined according to the virtual topology of the satellite network corresponding to each time slice, and the implementation process is as follows:

[0104] Let n be the number of satellite nodes in the virtual topology of the satellite network. According to the number of orbits and the number of satellites on each orbit in the virtual topology of the satellite network, the ground is evenly divided into different ground coverage areas according to longitude and latitude: R = {r1, r2,..., r n}, r i represents the ground coverage area corresponding to the i-th satellite node in the virtual topology of the satellite network;

[0105] According to the longitude and latitude of the satellite's movement in each time slice, determine the ground coverage area mapped by the satellite in each time slice to obtain the mapping relationship between the satellite and the ground coverage area in each time slice.

[0106] In an embodiment of the present invention, in step (3), each satellite node calculates the default routing table to the remaining satellite nodes in the virtual topology of the satellite network using the shortest path algorithm, and the implementation process is as follows:

[0107] Step (3a-2), each satellite node counts the link state information and performs interaction, and defines a real-time link cost metric, and the calculation formula is as follows:

[0108] L cost (t) = T prop + T queue (t);

[0109] Where, L c o st (t) is the real-time link cost metric at time t, T prop is the propagation delay of the link, and T queue (t) is the queuing delay of the link at time t;

[0110] Step (3b-2), use the real-time link cost metric as the path weight;

[0111] Step (3c-2), select a certain satellite node s in the virtual topology of the satellite network, and establish two sets for the satellite node s: a source node set A and a destination node set B;

[0112] Step (3d-2), initially, the source node set A only contains the satellite node s, and the destination node set B contains the other satellite nodes in the satellite network virtual topology except the satellite node s;

[0113] Step (3e-2), select the satellite node k with the minimum path weight from the destination node set B, add the satellite node k to the source node set A, and at the same time, remove the satellite node k from the destination node set B;

[0114] Step (3f-2), update the path weights from each satellite node in the destination node set B to the satellite node s, that is, for the case where (s,v)>(s,k)+(k,v), update (s,v) to (s,k)+(k,v), where (s,v) is the path weight from the satellite node s to the satellite node v, (s,k) is the path weight from the satellite node s to the satellite node k, and (k,v) is the path weight from the satellite node k to the satellite node v;

[0115] Step (3g-2), repeat steps (3e-2) to (3f-2) until all satellite nodes in the satellite network virtual topology are traversed, and obtain the shortest paths from the satellite node s to the other satellite nodes in the satellite network virtual topology;

[0116] Step (3h-2), delete the satellite nodes in the shortest paths from the destination node set B, and re-execute steps (3e-2) to (3g-2) to obtain the alternative paths in the satellite network virtual topology;

[0117] Step (3i-2), perform the process of steps (3c-2) to (3h-2) for all satellite nodes in the satellite network virtual topology, obtain the shortest paths and alternative paths from all satellite nodes in the satellite network virtual topology to the other satellite nodes, and generate and store the default routing table at the corresponding satellite nodes according to the shortest paths and alternative paths. The specific format is shown in Table 1.

[0118] Table 1 Default Routing Table Format

[0119] Target satellite Primary selected shortest path Alternative path Satellite identifier Output port 1 Output port 2

[0120] Step (4), the ground control center calculates and establishes multiple LSP paths between the coverage areas of each time slice according to the global regional traffic distribution model, the satellite network virtual topology, and the service type and QoS requirements.

[0121] In an embodiment of the present invention, when calculating the LSP path in step (4), the services are classified according to the QoS requirements, and each type of service uses the Bellman-Ford or genetic algorithm, but is not limited to these methods, to calculate the LSP path that meets the QoS requirements.

[0122] It can be seen that each LSP path can accommodate one or several types of services, adopting the idea of coarse-grained pipeline transmission, thus simplifying the number of established LSP paths. Therefore, the LSP path is transformed from the actual path between terminals into a virtual logical channel between coverage areas, solving the problem of frequent changes in the LSP path caused by terminal movement or handover of satellite nodes serving the current coverage area.

[0123] Step (5): The ground control center generates relevant table entries corresponding to each time slice according to the calculated LSP path. The relevant table entries include the FEC label mapping table generated by the ground control center for users, as well as the LSP label forwarding table and coverage area mapping table generated by the ground control center for the LEO satellite constellation.

[0124] In an embodiment of the present invention, the implementation process of the ground control center generating relevant table entries corresponding to each time slice in step (5) is as follows:

[0125] Step (5a): The ground control center generates an FEC label mapping table for users; the FEC label mapping table is the mapping relationship between multi-tuples and labels; and then it is sent to terminals in each coverage area; among them, the multi-tuples include the source terminal, destination terminal, QoS requirements, protocol type, but are not limited to these information; the labels are globally and uniformly assigned by the ground control center using the method of globally allocating labels and have the uniqueness of allocation. The uniqueness of label allocation means that the same "input port + input label" should not appear in multiple satellite nodes. The format of the FEC label mapping table is shown in Table 2.

[0126] Table 2 FEC label mapping table

[0127] Tuple Input label Tuple 1 Label 1

[0128] Step (5b): The ground control center generates an LSP label forwarding table and a coverage area mapping table for LEO satellites; and then the LSP label forwarding tables of each time slice, as well as the FEC label mapping table and the coverage area mapping table are uploaded to satellite nodes; among them, the LSP label forwarding table is the mapping relationship from "input label + input port" to "output port"; the coverage area mapping table is the mapping relationship between satellite nodes and coverage areas. When a satellite switches its coverage area, it only needs to forward according to the LSP label forwarding table of the new time slice. The format of the LSP label forwarding table is shown in Table 3.

[0129] Table 3 LSP label forwarding table

[0130] Time slice serial number Input port Input label Output port 1 Port 1 Label 1 Port 2

[0131] Step (6): If the upper injection time of the LSP label forwarding table is reached or the calculation and update of the default routing table are triggered due to the change of the virtual topology of the satellite network, the ground control center will upload the newly generated LSP label forwarding table to the satellite node, and send the newly generated FEC label mapping table and coverage area mapping table to the terminal.

[0132] It can be seen that in the embodiment of the present invention, when the upper injection time of the LSP label forwarding table or the virtual topology of the satellite network changes, the default routing table is recalculated and updated. At the same time, according to the newly generated LSP label forwarding table, as well as the FEC label mapping table and the coverage area mapping table, the subsequent process is continued. For example, here, multiple LSP paths are recalculated and established between the coverage areas of each time slice according to step (4).

[0133] Step (7): When the user source terminal sends a service, it knows whether to use the label forwarding method according to its FEC label mapping table. If so, it queries the corresponding label of the service according to the FEC label mapping table, constructs a data packet and adds the corresponding label field, and sends it to the satellite node serving the current coverage area.

[0134] In an embodiment of the present invention, the data packet constructed in step (7) includes the destination coverage area, the source coverage area, the destination terminal identifier, and the source terminal identifier; among them, the destination coverage area identifier is used to query the identifier of the destination satellite during connectionless forwarding, and the destination terminal identifier is used to send to the destination terminal after reaching the destination satellite. Correspondingly, please refer to Figure 4 , the steps implemented in step 7 of the embodiment of the present invention are as follows:

[0135] Step (7a): The terminal queries its own destination terminal table, which contains the information of the destination terminal and the coverage area where it is located. If there is no relevant entry in the table, it queries the location of the destination terminal from the ground control center, and adds the relevant entry after the ground control center replies. The format of the destination terminal table is shown in Table 4. When the update countdown is reduced to 0, the current user sends a location query to the ground control center station. When the survival time is reduced to 0 (no data packet has been sent to this user terminal for a certain period of time), this entry is deleted.

[0136] Table 4 Destination Terminal Table

[0137] Target terminal Coverage area address Time to live Update countdown Terminal 1 Coverage area 1 T1 U1

[0138] Step (7b): The terminal constructs a data packet with the data format shown in Figure 5 , and fills in the source coverage area and the destination coverage area in the data packet. The meanings of the fields in this data packet are shown in Table 5.

[0139] Table 5 Meanings of the Fields in the Data Packet

[0140]

[0141]

[0142] Step (7c), the terminal queries its own FEC label mapping table to check whether there is a mapping relationship between the multi-tuple and the label.

[0143] Step (7d), if there is a label mapping, set the label forwarding field to 1, and use the label forwarding mechanism to fill the queried label into the corresponding label field. If there is no label mapping, set the label forwarding field to 0 and use the connectionless forwarding mechanism.

[0144] Step (7e), the terminal sends the encapsulated data packet to the satellite node serving the current coverage area.

[0145] Step (8), after receiving the data packet, the satellite uses different LSP label forwarding tables in each time slice to query the label forwarding field and selects the corresponding forwarding mechanism to forward the packet.

[0146] In an embodiment of the present invention, in step (8), using different LSP label forwarding tables in each time slice to query the label forwarding field and selecting the corresponding forwarding mechanism for the packet forwarding mechanism is implemented as follows:

[0147] Step (8a), if the label forwarding field uses the label forwarding method, query its LSP label forwarding table to obtain the corresponding output port and forward it to the next-hop satellite;

[0148] Step (8b), if the label forwarding field does not use the label forwarding method, query the default routing table and the coverage area mapping table and forward it to the next-hop satellite;

[0149] Step (8c), if the current satellite is the destination satellite, forward the service to the destination terminal.

[0150] For example, please refer to Figure 6 , after the satellite receives the data packet, it uses different LSP label forwarding tables in each time slice to query the label forwarding field. Specifically:

[0151] When the label forwarding field is 1, it indicates that the label forwarding method can be used. Extract the label field in the frame format, query its LSP label forwarding table, find the output port corresponding to the label, forward it to the next-hop satellite, and continue to determine whether the current satellite is the destination satellite. If so, forward the service to the destination terminal. If not, forward the service to the next-hop satellite.

[0152] When the label forwarding field is 0, it indicates that the label forwarding method may not be adopted. The on-board forwarding adopts a connectionless mechanism. The destination coverage area field in the data packet is extracted, the destination satellite is obtained according to the mapping relationship between the coverage area and the satellite, the default routing table is queried, the next-hop address of the destination satellite is found, and it is continuously determined whether the current satellite is the destination satellite. If so, the service is forwarded to the destination terminal; if not, the service is forwarded to the next-hop satellite.

[0153] Step (9): If a link failure or satellite node failure occurs in the virtual topology of the satellite network, the current fault information is notified to the ground control center, and the processes of steps (3) to (6) are executed, and the normal service sending process is continued, such as steps (7) to (8), step (10); if all satellite nodes in the virtual topology of the satellite network are operating normally, the satellite still periodically counts the network status and summarizes it to the ground control center. Here, the periodic counting of the network status can control the ground control center to select the on-board that operates normally to execute the method of the present invention.

[0154] Step (10): After receiving the data packet, the destination terminal removes the packet header, extracts the payload field, obtains the transmitted service, and sends the service to the upper layer for processing. Here, the upper layer can be the flow direction of the final service distribution, such as the application layer.

[0155] In summary, the on-board label forwarding method based on time slices proposed in the embodiments of the present invention adopts the idea of time slices, uses the ground fixed coverage area and satellite handover time to divide time slices, and regards the topological structure of the space-ground network as fixed within each time slice, converting the dynamic topology of the space-ground network into a static topology, which is convenient for routing calculation. Therefore, it can well adapt to the topological dynamics of the space-ground network. In the embodiments of the present invention, since the ground control center uses centralized offline calculation to calculate the LSP paths between each pair of coverage areas and upload them according to time slices, there is no need for satellite nodes to calculate the routing paths of label forwarding, thus reducing the complexity of on-board calculation. During the on-board label switching process, the satellite node only needs to query the label field of the data packet and the label forwarding table, reducing the complexity of on-board forwarding processing. When the ground control center calculates the label forwarding path offline in the embodiments of the present invention, it calculates the routing through the link state feedback by the satellite and the global regional traffic distribution model. The routing path planned in this way can better guarantee the user QoS and improve the utilization rate of inter-satellite links. When the ground control center calculates the label forwarding path offline in the embodiments of the present invention, a coarse-grained pipeline is established for each pair of coverage areas, and an LSP is not calculated for each service. Therefore, multiple services can use the same LSP for transmission, which can reduce the complexity of LSP establishment and signaling overhead. The survival time of the LSP is the same as that of the time slice. As the current time slice ends, the valid LSP forwarding table of the next time slice is adopted, which can avoid the problem of frequent establishment and removal of LSPs caused by the end of the service or user movement. It can be seen that in the embodiments of the present invention, the ground control center pre-calculates the LSP label forwarding paths of different time slices and reserves on-board resources, and each satellite node stores multiple LSP label forwarding tables of different time slices respectively. When performing service forwarding on board, the relevant entry in the forwarding table is queried according to the content of the label field of the data packet in the current time slice, and the data packet is forwarded on the pre-established LSP label forwarding path. This method can provide QoS guarantee for multiple types of connection-oriented services, reduce the on-board calculation complexity, well adapt to the highly dynamic topology of the space-ground network, and reduce routing signaling overhead.

[0156] Please refer to Figure 7 , the embodiments of the present invention provide an electronic device, including a processor 701, a communication interface 702, a memory 703, and a communication bus 704. Among them, the processor 701, the communication interface 702, and the memory 703 complete mutual communication through the communication bus 704;

[0157] The memory 703 is used to store computer programs;

[0158] When the processor 701 is used to execute the program stored in the memory 703, it implements the steps of the above on-board label forwarding method based on time slices.

[0159] An embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the steps of the above-mentioned on-board label forwarding method based on time slices are implemented.

[0160] As for the device / electronic device / storage medium embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments.

[0161] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0162] Although the present invention is described herein in conjunction with various embodiments, those skilled in the art may understand and implement other variations of the disclosed embodiments by reviewing the specification and accompanying drawings in the process of implementing the claimed invention. In the specification, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple components or steps. The fact that certain measures are described in different embodiments does not mean that these measures cannot be combined to produce good results.

[0163] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for on-board label forwarding based on time slices, characterized in that Including the following steps: Step (1): Adopt an inclined orbit LEO satellite constellation. Under normal operation, the satellite topology remains stable and unchanged; Adopt the idea of an earth-fixed coverage area, divide the ground area into multiple coverage areas, and within a certain period of time, each coverage area is served by a LEO satellite constellation; Step (2): According to the coverage areas divided in step (1), as the satellite moves and the earth rotates, the satellite will switch from the current coverage area to the next coverage area. According to the switching time of the satellite between the coverage areas, it is divided into multiple time slices; Step (3): The ground control center determines the mapping relationship between the coverage area and the satellite according to the virtual topology of the satellite network corresponding to each time slice; at the same time, each satellite node uses the shortest path algorithm to calculate the default routing table to the remaining nodes in the virtual topology of the satellite network, and this default routing table is used for connectionless forwarding and link failure handling; Step (4): The ground control center calculates and establishes multiple LSP paths between the coverage areas of each time slice according to the global regional traffic distribution model, the virtual topology of the satellite network, as well as the service type and QoS requirements; Step (5): The ground control center generates the relevant table entries corresponding to each time slice according to the calculated LSP paths. The relevant table entries include the FEC label mapping table generated by the ground control center for users, as well as the LSP label forwarding table and the coverage area mapping table generated by the ground control center for the LEO satellite constellation; Step (6): If it reaches the uploading time of the LSP label forwarding table or the calculation and update of the default routing table are triggered due to changes in the virtual topology of the satellite network, the ground control center uploads the newly generated LSP label forwarding table to the satellite node, and sends the newly generated FEC label mapping table and the coverage area mapping table to the terminal; Step (7): When the user source terminal sends a service, it knows whether to use the label forwarding method according to its FEC label mapping table. If so, it queries the corresponding label of the service according to the FEC label mapping table, constructs a data packet and adds the corresponding label field, and sends it to the satellite node serving the current coverage area; Step (8): After receiving the data packet, the satellite node queries the label forwarding field using different LSP label forwarding tables in each time slice, and selects the corresponding forwarding mechanism to forward the packet; Step (9): If there is a link failure or satellite node failure in the virtual topology of the satellite network, the current failure information will be informed to the ground control center, and the processes of steps (3) to (6) will be executed, and the normal service sending process will continue; If all satellite nodes in the virtual topology of the satellite network are operating normally, the satellite still periodically counts the network status and summarizes it to the ground control center; Step (10): After receiving the data packet, the destination terminal removes the packet header, extracts the payload field, obtains the transmitted service, and sends the service to the upper layer for processing.

2. The on-board tag forwarding method based on time slices according to claim 1, wherein The implementation process of the division of multiple coverage areas in step (1) is as follows: Adopt the earth-fixed footprint mode, and the satellite controls its beam to provide services for a certain coverage area within a certain period of time.

3. The on-board tag forwarding method based on time slices according to claim 1, wherein The implementation process of the division of time slices in step (2) is as follows: Step (2a), according to the selected satellite, calculate the handover time interval within its orbit, and the calculation formula is as follows: where t intra is the switching time interval within the orbit, T is the satellite orbit period, and SATE_PER_ORBIT is the number of satellites on each orbit; Step (2b), calculate the handover time interval between orbits, and the calculation formula is as follows: Among them, t inter is the switching time interval between orbits, φ is the longitude span angle of the coverage area, ω earth is the angular velocity of the Earth's rotation; Step (2c), adopt the synchronous handover method. When one satellite switches to the next coverage area, all other satellites must perform the same action; the ground control center calculates the handover time of the satellites according to the handover time intervals within the orbit and between orbits obtained in Step (2a) to Step (2b), and divides multiple time slices according to the handover time; among them, the satellite-ground network topology relationship within each time slice is regarded as static and unchanged.

4. The on-board tag forwarding method based on time slices according to claim 1, characterized in that The implementation process of the ground control center determining the virtual topology of the satellite network in Step (3) is as follows: Step (3a-1): Let n be the number of satellite nodes in the virtual topology of the satellite network. Different time slices are denoted as t1, t2,..., t k ,..., t m , t k k. Let m be the number of time slices. For the k-th time slice t k k, represent the virtual topology of the satellite network with a directed graph G; Among them, V = {v1, v2,..., v n} is the set of satellite nodes in the virtual topology of the satellite network, n represents the number of satellite nodes in the virtual topology of the satellite network, is the set of available inter-satellite links; Step (3b-1), set e ij as the inter-satellite link from the i-th satellite to the j-th satellite. When e ij is an available inter-satellite link, its value is 1; otherwise, its value is 0, that is Step (3c-1), according to e ij calculate the directed graph adjacency matrix of to obtain the virtual topology of the satellite network at the k-th time slice t k ; Step (3d-1), repeat Step (3a-1) to Step (3c-1) for a total of m times to obtain the virtual topology of the satellite network for all time slices.

5. The on-board tag forwarding method based on time slices according to claim 1, characterized in that The implementation process of determining the mapping relationship between the satellite and the ground coverage area according to the virtual topology of the satellite network corresponding to each time slice in Step (3) is as follows: Let \(n\) be the number of satellite nodes in the virtual topology of the satellite network. According to the number of orbits and the number of satellites in each orbit in the virtual topology of the satellite network, the ground is evenly divided into different ground coverage areas according to longitude and latitude: \(R = \{r_1, r_2, \ldots, r n \}\), where \(r i represents the ground coverage area corresponding to the \(i\)-th satellite node in the virtual topology of the satellite network; According to the longitude and latitude of the satellite's movement in each time slice, determine the ground coverage area mapped by it in each time slice, and obtain the mapping relationship between the satellite and the ground coverage area for each time slice.

6. The on-board tag forwarding method based on time slices according to claim 1, wherein, The implementation process of each satellite node calculating the default routing table to the other satellite nodes in the virtual topology of the satellite network using the shortest path algorithm in Step (3) is as follows: Step (3a-2), each satellite node counts the link state information and performs interaction, and defines the real-time link cost metric, and the calculation formula is as follows: L cost L(t)=T prop +T queue (t); Among them, L c o st (t) is the real-time link cost metric at time t, T prop is the propagation delay of the link, T queue (t) is the queuing delay of the link at time t; Step (3b-2), use the real-time link cost metric as the path weight; Step (3c-2), select a certain satellite node s in the virtual topology of the satellite network, and set up two sets for the satellite node s: the source node set A and the destination node set B; Step (3d-2), initially, the source node set A only contains the satellite node s, and the destination node set B contains the other satellite nodes in the virtual topology of the satellite network except the satellite node s; Step (3e-2), select the satellite node k with the smallest path weight from the destination node set B, add the satellite node k to the source node set A, and at the same time, remove the satellite node k from the destination node set B; Step (3f-2), update the path weights of each satellite node in the destination node set B to the satellite node s, that is, for the case of (s,v)>(s,k)+(k,v), update (s,v) to (s,k)+(k,v), where (s,v) is the path weight from the satellite node s to the satellite node v, (s,k) is the path weight from the satellite node s to the satellite node k, and (k,v) is the path weight from the satellite node k to the satellite node v; Step (3g-2), repeat Step (3e-2) to (3f-2) until all satellite nodes in the virtual topology of the satellite network are traversed to obtain the shortest path from the satellite node s to the other satellite nodes in the virtual topology of the satellite network. Step (3h-2): Delete the satellite nodes in the shortest path from the destination node set B, and re-execute steps (3e-2) to (3g-2) to obtain the alternative paths in the virtual topology of the satellite network. Step (3i-2): Perform the process of steps (3c-2) to (3h-2) for all satellite nodes in the virtual topology of the satellite network to obtain the shortest paths and alternative paths from all satellite nodes to other satellite nodes in the virtual topology of the satellite network, and generate and store the default routing table at the corresponding satellite nodes according to the shortest paths and alternative paths.

7. The on-board tag forwarding method based on time slices according to claim 1, characterized in that When calculating the LSP path in step (4), the services are classified according to QoS requirements, and each type of service uses the Bellman-Ford or genetic algorithm to calculate the LSP path that meets the QoS requirements.

8. The on-board tag forwarding method based on time slices according to claim 1, characterized in that, In step (5), the process of the ground control center generating the relevant table entries corresponding to each time slice according to the calculated LSP path is as follows: Step (5a): The ground control center generates an FEC label mapping table for the user; the FEC label mapping table is the mapping relationship between the multi-tuples and the labels; then it is sent to the terminals in each coverage area; among them, the multi-tuples include the source terminal, the destination terminal, the QoS requirements, and the protocol type; the labels are globally and uniformly assigned by the ground control center and have unique assignment, and the unique assignment of the labels means that the same "input port + input label" should not appear among multiple satellite nodes. Step (5b): The ground control center generates an LSP label forwarding table and a coverage area mapping table for the LEO satellite; then it notifies the satellite nodes of the LSP label forwarding table for each time slice, as well as the FEC label mapping table and the coverage area mapping table; among them, the LSP label forwarding table is the mapping relationship from "input label + input port" to "output port"; the coverage area mapping table is the mapping relationship between the satellite nodes and the coverage areas.

9. The on-board tag forwarding method based on time slices according to claim 1, wherein The data packet constructed in step (7) includes the destination coverage area, the source coverage area, the destination terminal identifier, and the source terminal identifier; among them, the destination coverage area identifier is used to query the identifier of the destination satellite during connectionless forwarding, and the destination terminal identifier is used to send to the destination terminal after reaching the destination satellite.

10. The on-board tag forwarding method based on time slices according to claim 1, wherein In step (8), the process of using different LSP label forwarding tables to query the label forwarding field in each time slice and selecting the corresponding forwarding mechanism for packet forwarding is as follows: Step (8a): If the label forwarding field uses the label forwarding method, query its LSP label forwarding table to obtain the corresponding output port and forward it to the next-hop satellite. Step (8b): If the label forwarding field does not use the label forwarding method, query the default routing table and the coverage area mapping table and forward it to the next-hop satellite. Step (8c): If the current satellite is the destination satellite, forward the service to the destination terminal.

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