A low earth orbit satellite network routing method for continuous communication

Abstract

The application discloses a low-orbit satellite network optimal path cooperative routing MILP method for continuous communication and belongs to the technical field of low-orbit satellite network space-time routing planning, and comprises the following steps.Step 1: defining parameter representation of low-orbit satellite communication network attribute data, including network distribution, communication link contact window and the like;Step 2: establishing a low-orbit satellite network optimal path cooperative routing MILP model for continuous communication based on a time-expanded network and a feasible flow theory, taking spatial link configuration and time switching sequence of the low-orbit satellite network optimal path cooperative routing as decision variables, taking maximization of end-to-end communication duration provided by the optimal path cooperative routing and minimization of switching times as optimization objectives, and comprehensively considering high-dynamic time-varying topology and multi-path cooperative routing of the low-orbit satellite communication network;Step 3: solving the low-orbit satellite network optimal path cooperative routing MILP model for continuous communication through a branch and bound algorithm to obtain the low-orbit satellite network optimal path cooperative routing with maximized end-to-end communication duration and minimized switching times.The application can break through the limitation of single-link routing "planning-interruption-replanning" and provide a reliable benchmark solution for spatial link construction and time switching planning of the low-orbit satellite network optimal path cooperative routing.

Description

Technical Field

[0001] This invention relates to the field of spatiotemporal routing planning technology for low-Earth orbit satellite networks, specifically to a MILP (Multi-Path Cooperative Routing) method for low-Earth orbit satellite networks with continuous communication. Background Technology

[0002] In building a next-generation cross-domain integrated information network with global coverage, high bandwidth, and low latency, low-Earth orbit (LEO) satellite constellations, as the core architecture of the space domain network, directly determine the efficiency of space-based communication services through their continuous routing and coordinated switching. LEO satellite networks must maintain persistent end-to-end connectivity under multiple spatiotemporal constraints, including high-speed satellite motion, periodic interruptions in inter-satellite links, and limited satellite-to-ground communication windows, to support critical services such as remote sensing data backhaul, emergency real-time command and control, and global intelligent interconnection.

[0003] Existing routing methods for low-Earth orbit satellite networks generally limit their optimization objectives to seeking instantaneous optimality or single-cycle path planning. While these methods can obtain efficient paths within a single time snapshot, the resulting paths are often rapidly interrupted due to satellite motion, forcing service flows to frequently switch to new paths. In long-duration communication tasks, this creates a negative cycle of "planning-interruption-replanning." This routing logic based on static or short-sighted optimization fundamentally contradicts the persistent connectivity requirements of highly dynamic environments. It cannot construct a global optimization strategy that maximizes end-to-end communication time, nor can it achieve stable transmission that minimizes the number of service interruptions. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a MILP (Multi-Path Cooperative Routing) method for low-Earth orbit (LEO) satellite networks with optimal paths for continuous communication. Based on time-spreading networks and feasible flow theory, a MILP model for LEO satellite networks with optimal paths for continuous communication is constructed. By proactively pre-setting and scheduling multiple high-quality paths, the service continuity and smooth transition capabilities of LEO satellite networks are improved. This yields optimal path cooperative routes that maximize end-to-end communication duration while minimizing the number of handovers. This provides a reliable benchmark solution for spatial link construction and time handover planning in LEO satellite network optimal path cooperative routing, and enhances the theoretical completeness and engineering applicability of persistent data routing strategies in the highly dynamic environment of low-Earth orbit.

[0005] A cooperative routing (MILP) method for optimal paths in low-Earth orbit satellite networks for continuous communication includes the following steps:

[0006] Step 1: Define the parameter representation of low-Earth orbit satellite communication network attribute data;

[0007] Specifically: Let N be the set of nodes that make up the low-Earth orbit satellite communication network, i be the index of the node and i = 1, 2, ..., |N|, where the ground terminal source point is O, the ground terminal sink point is D, the set of communication links between any pair of nodes is L, (i, j) is the index of the communication link, and the set of contact time windows of communication link (i, j) is W. ij w is the index of the contact time window and w = 1, 2, …, |W ij Let P be the set of end-to-end communication paths within the planning period, where p is the index of the path and p = 1, 2, …, |P|. Let ls be the start time of the w-th contact time window of communication link (i, j). ijw The termination time of the w-th contact time window of the communication link (i, j) is le ijw M is a large number, such as 9999.

[0008] Step 2: Based on time-extended networks and feasible flow theory, establish a MILP model for optimal path cooperative routing in low-Earth orbit satellite networks for continuous communication. The spatial link configuration and time switching order of optimal path cooperative routing in low-Earth orbit satellite networks are used as decision variables. The optimization objective is to maximize the end-to-end communication duration provided by optimal path cooperative routing and minimize the number of switching. The highly dynamic time-varying topology and multi-path cooperative routing of low-Earth orbit satellite communication networks are considered in a comprehensive manner. The specific method is as follows.

[0009] Step 2.1: Define the decision variables for low-Earth orbit satellite communication networks;

[0010] x ijwp : A variable of 0 or 1, which is 1 if and only if the communication link (i, j) is used to construct path p in its w-th contact time window, otherwise it is 0;

[0011] y p : A variable that is 0 or 1, and is 1 if and only if the p-th end-to-end communication path is successfully constructed, otherwise it is 0;

[0012] rs p : The start time of the p-th communication path;

[0013] re p : The end time of the p-th communication path;

[0014] CS: Start time of end-to-end continuous communication consisting of seamless path switching;

[0015] CE: End time of end-to-end continuous communication consisting of seamless path switching;

[0016] Step 2.2: Establish the objective function for cooperative optimal path planning in low-Earth orbit satellite communication networks for continuous communication;

[0017] (1)

[0018] The objective function Continuity includes the end-to-end continuous communication duration consisting of seamless path switching. And the penalty for the number of paths used to avoid frequent switching ;

[0019] Step 2.3: Establish a formalized representation of the end-to-end communication process based on the network flow method;

[0020] (2)

[0021] (3)

[0022] (4)

[0023] (5)

[0024] (6)

[0025] (7)

[0026] (8)

[0027] (9)

[0028] Step 2.4: Calculate the start and end times of each end-to-end communication path;

[0029] (10)

[0030] (11)

[0031] (12)

[0032] (13)

[0033] Step 2.5: Establish switching order constraints for each end-to-end communication path;

[0034] (14)

[0035] (15)

[0036] (16)

[0037] Step 2.6: Calculate the end-to-end continuous communication period constituted by the seamless switching of communication paths;

[0038] (17)

[0039] (18)

[0040] (19)

[0041] (20)

[0042] Step 2.7: Variable value constraints;

[0043] (twenty one)

[0044] (twenty two)

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] This invention introduces a superior path cooperative routing mechanism, breaking through the traditional mindset of single-slice paths or short-sighted switching routes. It proactively plans end-to-end superior path cooperative routing schemes for continuous communication within the operational cycle of low-Earth orbit satellite networks at a spatiotemporal global level, forming multiple spatially reachable and temporally interconnected high-quality paths, effectively avoiding the negative cycle of "connection-interruption-reconnection". Simultaneously, this invention constructs a solvable MILP model based on mathematical programming theory, capable of obtaining precise optimal solutions for the longest duration and fewest switching times of end-to-end communication in low-Earth orbit satellite networks based on spatial link construction and temporal switching planning, thus improving the theoretical completeness and engineering applicability of persistent data routing strategies in the highly dynamic environment of low-Earth orbit. Attached Figure Description Figure 1 This is a flowchart of the MILP (Multi-Path Cooperative Routing) method for low-Earth orbit satellite networks with continuous communication as described in this invention. Figure 2 This is a schematic diagram of cooperative routing for optimal paths in low-Earth orbit satellite networks. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] A cooperative routing (MILP) method for optimal paths in low-Earth orbit satellite networks for continuous communication includes the following steps:

[0049] Step 1: Define the parameter representation of low-Earth orbit satellite communication network attribute data;

[0050] Specifically: Let N be the set of nodes that make up the low-Earth orbit satellite communication network, i be the index of the node and i = 1, 2, ..., |N|, where the ground terminal source point is O, the ground terminal sink point is D, the set of communication links between any pair of nodes is L, (i, j) is the index of the communication link, and the set of contact time windows of communication link (i, j) is W. ij w is the index of the contact time window and w = 1, 2, …, |W ij Let P be the set of end-to-end communication paths within the planning period, where p is the index of the path and p = 1, 2, …, |P|. Let ls be the start time of the w-th contact time window of communication link (i, j). ijw The termination time of the w-th contact time window of the communication link (i, j) is le ijw M is a large number, such as 9999.

[0051] Step 2: Based on time-extended networks and feasible flow theory, establish a MILP model for optimal path cooperative routing in low-Earth orbit satellite networks for continuous communication. The spatial link configuration and time switching order of optimal path cooperative routing in low-Earth orbit satellite networks are used as decision variables. The optimization objective is to maximize the end-to-end communication duration provided by optimal path cooperative routing and minimize the number of switching. The highly dynamic time-varying topology and multi-path cooperative routing of low-Earth orbit satellite communication networks are considered in a comprehensive manner. The specific method is as follows.

[0052] Step 2.1: Define the decision variables for low-Earth orbit satellite communication networks;

[0053] x ijwp : A variable of 0 or 1, which is 1 if and only if the communication link (i, j) is used to construct path p in its w-th contact time window, otherwise it is 0;

[0054] y p : A variable that is 0 or 1, and is 1 if and only if the p-th end-to-end communication path is successfully constructed, otherwise it is 0;

[0055] rs p : The start time of the p-th communication path;

[0056] re p : The end time of the p-th communication path;

[0057] CS: Start time of end-to-end continuous communication consisting of seamless path switching;

[0058] CE: End time of end-to-end continuous communication consisting of seamless path switching;

[0059] Step 2.2: Establish the objective function for continuous routing planning of low-Earth orbit satellite communication networks;

[0060] (twenty three)

[0061] The objective function Continuity includes the end-to-end continuous communication duration consisting of seamless path switching. And the penalty for the number of paths used to avoid frequent switching ;

[0062] Step 2.3: Establish a formalized representation of the end-to-end communication process based on the network flow method;

[0063] (twenty four)

[0064] (25)

[0065] (26)

[0066] (27)

[0067] (28)

[0068] (29)

[0069] (30)

[0070] (31)

[0071] Step 2.4: Calculate the start and end times of each end-to-end communication path;

[0072] (32)

[0073] (33)

[0074] (34)

[0075] (35)

[0076] Step 2.5: Establish switching order constraints for each end-to-end communication path;

[0077] (36)

[0078] (37)

[0079] (38)

[0080] Step 2.6: Calculate the end-to-end continuous communication period constituted by the seamless switching of communication paths;

[0081] (39)

[0082] (40)

[0083] (41)

[0084] (42)

[0085] Step 2.7: Variable value constraints;

[0086] (43)

[0087] (44)

[0088] Step 3: Solve the MILP model of optimal path cooperative routing for low-Earth orbit satellite networks for continuous communication to obtain the optimal path cooperative routing spatial link configuration and time switching sequence that maximizes end-to-end communication duration and minimizes the number of handovers.

[0089] This implementation uses the branch and bound algorithm embedded in the commercial MILP solver CPLEX 12.9.0 on the GNU / Linux 4.15.0-142-generic x86_64 operating system to solve the model;

[0090] To demonstrate the superiority of the method proposed in this invention, this embodiment names the MILP model constructed by this invention as Optimal Path Cooperative Routing Model 1, or simply Model 1, and refers to the single-link routing model that does not consider optimal path cooperation as Single-Link Routing Model 2, or simply Model 2.

[0091] To facilitate the representation of model results, this embodiment introduces several symbols to represent the results of each model: the optimal objective function value obtained by the model is represented by Continuity, the end-to-end continuous communication duration consisting of seamless path switching is represented by Dur, the number of paths required to provide Dur is represented by Count, and the corresponding computation time is represented by CT.

[0092] To facilitate the quantification of model differences, this embodiment introduces the difference in end-to-end continuous communication duration between indicator nodes, using D. Dur The calculation formula is shown below:

[0093] (45)

[0094] The CAS100ATA ground station was selected as the end-to-end communication source node, the WDC500USA ground station was selected as the destination node, and the orbital data of the Iridium-NEXT constellation of 80 low-orbit satellites on July 10, 2025 were selected to construct the communication link and contact time window set. All satellites and ground nodes were selected to construct the network node set. The maximum allowable number of optimal paths was set to 4, and M was set to 9999.

[0095] The experimental results are shown in Table 1. In terms of solution efficiency, both routing models can find the optimal solution within seconds for all test instances. From the perspective of the objective function, Model 2, compared to Model 1, achieves a better end-to-end communication time through spatial link configuration and time switching order optimization of multiple end-to-end routes, with an average of 423.60 seconds and an average of 2.60 optimal paths constructed. The average D... Dur Reaching 91.27%;

[0096] Table 1 Comparison of results between the two models

[0097]

[0098] The comparison results above show that the optimal path cooperative routing method for low-Earth orbit satellite networks designed in this invention exhibits good service continuity and smooth transition in terms of end-to-end communication duration and the number of paths used. It breaks through the limitation of "planning-interruption-replanning" in single-link routing, provides a reliable benchmark solution for spatial link construction and time switching planning of optimal path cooperative routing for low-Earth orbit satellite networks, and improves the theoretical completeness and engineering applicability of persistent data routing strategies in the highly dynamic environment of low-Earth orbit.

Claims

1. A cooperative routing (MILP) method for optimal paths in low-Earth orbit satellite networks for continuous communication; comprising the following steps: (1) Define the parameter representation of attribute data for low-Earth orbit satellite communication networks; Let N be the set of nodes that make up the low-Earth orbit satellite communication network, and let i be the index of the node, where i = 1, 2, …, |N|. Let O be the source node of the ground terminal and D be the sink node of the ground terminal. Let L be the set of communication links that make up any pair of nodes, and let (i, j) be the index of the communication link. Let W be the set of contact time windows that make up the communication link (i, j). ij w is the index of the contact time window and w = 1, 2, …, |W ij Let P be the set of end-to-end communication paths within the planning period, where p is the index of the path and p = 1, 2, …, |P|. Let ls be the start time of the w-th contact time window of communication link (i, j). ijw The termination time of the w-th contact time window of the communication link (i,j) is le. ijw M is a large number, such as 9999; (2) Based on time-extended network and feasible flow theory, a MILP model for optimal path cooperative routing of low-Earth orbit satellite network for continuous communication is established. The spatial link configuration and time switching order of optimal path cooperative routing of low-Earth orbit satellite network are used as decision variables. The optimization objective is to maximize the end-to-end communication duration provided by optimal path cooperative routing and minimize the number of switching. The highly dynamic time-varying topology and multi-path cooperative routing of low-Earth orbit satellite communication network are considered in a comprehensive manner. The specific method is as follows. (2.1) Define x ijwp The variable y represents either 0 or 1, and is 1 if and only if the communication link (i, j) is used to construct path p in its w-th contact time window, otherwise it is 0; p The variable rs represents a value of 0 or 1, and is 1 if and only if the p-th end-to-end communication path is successfully established; otherwise, it is 0. p and re p Let represent the start and end times of the p-th communication path, respectively; define variables CS and CE to represent the start and end times of the end-to-end continuous communication formed by seamless switching of all communication paths, respectively. (2.2) Establish the objective function for cooperative optimal path planning in low-Earth orbit satellite communication networks for continuous communication: (2.3) Formulation of end-to-end communication process based on network flow method: (2.4) Calculate the start and end times of each end-to-end communication path: (2.5) Establish switching order constraints for each end-to-end communication path: (2.6) Calculate the end-to-end communication interval formed by seamless switching of communication paths: (2.7) Variable value constraints: (3) By solving the MILP model of optimal path cooperative routing for low-Earth orbit satellite networks for continuous communication through the branch and bound algorithm, we can obtain the optimal path cooperative routing for low-Earth orbit satellite networks that maximizes the end-to-end communication duration and minimizes the number of handovers. The limitation of "planning-interruption-replanning" of single-link routing is eliminated, and a reliable benchmark solution is provided for the spatial link construction and time handover planning of optimal path cooperative routing for low-Earth orbit satellite networks.

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