A multi-layer constellation inter-layer link design method with enhanced service coverage capability

Abstract

The present invention discloses a method for designing inter-layer links of multi-layer constellations with enhanced service coverage capability, comprising: constructing a large-scale multi-layer satellite network spanning T time slots, and obtaining the coordinates of all satellites in the multi-layer satellite network in each time slot under geocentric coordinates; constructing an adjacency matrix of each constellation layer in the multi-layer satellite network; constructing a feasible set of satellite links between two adjacent layers in each time slot multi-layer satellite network; constructing a ground non-uniform service model based on geographic population distribution, dividing the earth's surface into multiple logical regions; calculating the weight of each time slot inter-layer link in the satellite link feasible set; establishing an inter-layer link allocation model based on the weight of the inter-layer link; optimizing the inter-layer link set in the satellite link feasible set to obtain an optimized inter-layer link set. The present invention designs a large-scale satellite network inter-layer topology by constructing inter-layer links, improves the throughput of the multi-layer satellite network, and effectively enhances the service coverage capability for global non-uniform services.

Description

Technical Field

[0001] The present invention belongs to the technical field of multi-layer satellite networks, and in particular relates to a multi-layer constellation inter-layer link design method with enhanced service coverage capability. Background Art

[0002] Large-scale, multi-layer satellite networks are developing rapidly, aiming to provide high-quality services for global non-uniform services, such as high throughput, low latency, and highly reliable transmission. However, with the explosive growth in the number of satellites, the total average path length of the network has increased significantly. In particular, the relative independence and stability of each layer, coupled with the relatively high-speed movement of different satellites, makes collaboration between layers difficult, leading to degradation of network performance such as throughput. Therefore, the establishment of inter-layer links is urgent, especially communication links between multi-layer low-orbit satellite constellations. However, the establishment of inter-layer links directly affects the network topology, which in turn affects network transmission efficiency and ultimately network throughput. Considering the cost of constructing inter-layer links, maintaining network stability, and enhancing ground service coverage, how to construct inter-layer links to maximize network performance remains a huge challenge.

[0003] Multi-layer satellite networks are a new development direction and trend in satellite communication networks. Currently, most established satellite communication networks still utilize a single-layer satellite deployment, such as the Iridium and Globalstar systems. However, with the increasing demand for terrestrial applications, the uneven nature of terrestrial services, and the surge in the number of users, single-layer satellite constellations are no longer able to guarantee service quality. Compared to single-layer satellite constellations, multi-layer satellite networks can enhance service coverage and ensure service continuity for diverse services. Intersatellite links (ISLs) are a key component in enabling multi-layer satellite networks to deliver comprehensive services. However, due to the relative motion between satellites and between satellites and the Earth, ISLs can be blocked by the Earth, necessitating ISL handovers and changing the entire network topology, ultimately impacting transmission efficiency. For a network with a time-varying topology, management and scheduling become more complex and require significant human and material resources. Furthermore, user mobility management becomes increasingly difficult, leading to a sharp decline in the transmission capacity of the entire network due to link handovers. Therefore, the design of ISLs is crucial to improving the key performance of the entire network.

[0004] Existing inter-satellite link design methods primarily focus on designing inter-layer links between medium-orbit and low-orbit satellites, as well as inter-satellite links between single-layer LEO satellites. However, there is still a lack of inter-layer link design between large-scale, multi-layer LEO satellite constellations. In particular, given the limited number of antennas that LEO satellites can carry, constructing an inter-layer topology is a pressing issue. Therefore, it is necessary to design inter-layer links between multiple LEO satellites to reduce network topology changes, significantly improve network stability, and enhance the ability to enhance ground service coverage.

[0005] The development of large-scale constellations has significantly increased the algorithmic complexity of network topology construction. Furthermore, the mapping relationship between network performance and time-varying network topology configuration transformations has not been thoroughly explored, resulting in high algorithmic complexity for intersatellite link design. Therefore, for large-scale, multi-layered satellite constellations, designing a method to rapidly estimate key network performance and transform the multi-layer topology after adding inter-layer links to reduce the algorithmic complexity of constructing these links has become a critical issue.

[0006] Bai Weigang, Lv Haoqiang and others disclosed a method for designing inter-layer link topology for MEO and LEO in their published patent "Inter-layer link topology design for LEOMEO dual-layer satellite constellation" (application number: 202111507541.X). By designing a multi-layer constellation inter-layer information carrying capacity and topology stability evaluation model, the total inter-layer link rate is maximized based on the time evolution of the inter-layer topology, and the topological performance under the antenna parameter configuration is explored. Based on the virtual topology scheme, time slicing is used to establish the topological structure of each time slot, and a 0-1 integer linear programming scheme based on time evolution is designed. Under the constraints of visibility relationship, antenna transmission power and the number of inter-layer antennas, the topological sequence of the inter-layer link is designed to optimize the connection relationship between low-orbit satellites and high-orbit satellites, improve the inter-layer topology stability and inter-layer information carrying capacity, enhance the stability of the inter-layer link, and reduce the switching frequency of inter-layer satellite antennas. The patent document proposes a centralized decision-making inter-layer link allocation strategy, which extends the duration of the topology and reduces the constellation switching overhead. However, the scale of MEO and LEO is relatively small, and the proposed allocation strategy is not applicable to the coupling between large-scale low-orbit satellite constellations. In addition, there is a lack of analysis of the network performance differences caused by changes in the overall network structure characteristics. Summary of the Invention

[0007] To address the above-mentioned problems existing in the prior art, the present invention provides a method for designing large-scale multi-layer constellation inter-layer links with enhanced service coverage. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0008] The present invention provides a multi-layer constellation inter-layer link design method with enhanced service coverage capability, comprising:

[0009] S1: Construct a large-scale multi-layer satellite network spanning T time slots, and obtain the coordinates of all satellites in the multi-layer satellite network in each time slot in geocentric coordinates;

[0010] S2: constructing an adjacency matrix of each constellation in the multi-layer satellite network;

[0011] S3: constructing a feasible set of satellite links between two adjacent layers in the multi-layer satellite network in each time slot;

[0012] S4: Construct a ground non-uniform traffic model based on geographic population distribution, dividing the Earth's surface into multiple logical regions. The load of each logical region is obtained based on global network user data.

[0013] S5: Calculating the weight of the inter-layer link formed by two adjacent layers of satellites in each time slot in the satellite link feasible set according to the link duration and the link load;

[0014] S6: Establishing an inter-layer link allocation model according to the weight of the inter-layer link;

[0015] S7: Utilizing the inter-layer link allocation model, optimizing the inter-layer link set in the satellite link feasible set to obtain an optimized inter-layer link set.

[0016] In one embodiment of the present invention, the S1 includes:

[0017] S1a: Build a large-scale multi-layer satellite network;

[0018] S1b: Obtain constellation parameters and use the constellation parameters to calculate the longitude, latitude and altitude data information of each layer of satellites;

[0019] S1c: Using the longitude, latitude and altitude of each satellite in each layer in each time slot, the position coordinates of each satellite in each time slot in the geocentric coordinate system are obtained.

[0020] In one embodiment of the present invention, the S3 includes:

[0021] S3a: Let f(c,g) represent whether the cth satellite belonging to the i-th layer and the gth satellite belonging to the i+1-th layer meet the visibility condition, and calculate the maximum visible Euclidean distance d between the satellites in the two-layer constellation. max :

[0022]

[0023] Where H1 represents the orbital altitude of the i-th layer satellite constellation, H2 represents the orbital altitude of the i+1-th layer satellite constellation, Re represents the radius of the earth, ro represents the atmospheric altitude, 1≤c≤N1, 1≤g≤N2, N1 represents the total number of satellites in all orbits of the i-th layer, and N2 represents the total number of satellites in all orbits of the i+1-th layer;

[0024] S3b: Calculate the Euclidean distance between the cth satellite in the i-th layer and the gth satellite in the i+1-th layer If d c,g <d max , then f(c,g)=1, otherwise, f(c,g)=0, where (x c ,y c ,z c) represents the position coordinates of the cth satellite in the i-th layer, (x g ,y g ,z g ) represents the position coordinates of the g-th satellite in the i+1-th layer.

[0025] S3c: Using steps S3a and S3b, determine whether all satellite node pairs have visibility conditions, and store f(c,g) in F i,i+1 , obtain the satellite link feasible set F i,i+1 .

[0026] In one embodiment of the present invention, the S5 includes:

[0027] S51: Let y i,i+1 (u,v) indicates whether the u-th satellite from the i-th layer forms an inter-layer link with the v-th satellite from the i+1-th layer. If so, y i,i+1 (u,v)=1, if not, then y i,i+1 (u,v)=0;

[0028] S52: Order represents the total duration of the inter-layer link formed by the u-th satellite in the i-th layer and the v-th satellite in the i+1-th layer in the t-th time slot, represents the remaining time of the inter-layer link formed by the u-th satellite in the i-th layer and the v-th satellite in the i+1-th layer in the t-th time slot, and the time weight of the current inter-layer link is obtained as:

[0029]

[0030] S53: Let the traffic density of the coverage area of ​​the u-th satellite in the i-th layer in the x-th logical area be Map the current satellite traffic density to the corresponding inter-layer link load, and the inter-layer link load is recorded as The load weight of the corresponding inter-layer link is Among them, ρ x represents the traffic density of the xth logical area, represents the number of satellites in the i-th layer of the x-th logical region, and max(δ) represents the number of all The maximum value in the set δ;

[0031] S54: Obtain the comprehensive weight of the inter-layer link according to the time weight of the inter-layer link and the load weight of the inter-layer link:

[0032]

[0033] In one embodiment of the present invention, the expression of the inter-layer link allocation model is:

[0034]

[0035]

[0036]

[0037] Among them, ψ i,i+1 represents the average path length of the i-th layer and the i+1-th layer network, constraint (1) represents maximizing the link weight of the inter-layer link in each time slot, constraint (2) represents that the satellite of the i-th layer builds an inter-layer link at most once in a time slot, and constraint (3) represents that the satellite of the i+1-th layer builds an inter-layer link at most once in a time slot.

[0038] In one embodiment of the present invention, the S7 includes:

[0039] S7a: Let the number of inter-layer links be k, randomly construct a population P of m inter-layer links, and each population contains 300 non-repeating inter-layer links connecting k satellites randomly selected from the first layer and k satellites randomly selected from the second layer. Let it be the number of iterations, initialize it = 0, and let ψ be the initial average path length of the network;

[0040] S7b: Copy all inter-layer links of the jth population in the population P to generate n clone populations Q. The total number of populations is m+n. The total population is recorded as PQ, and set p c is the crossover probability, p x is the mutation probability, and p c +p x =1;

[0041] S7c: Let λ be the probability of random generation under the current number of iterations, and 0<λ<1. If λ <p c , then randomly select the population P in PQ a As the crossover population, all other populations are combined with P by single-point crossover. a Crossover; if λ≥p c , then jump to S7d;

[0042] S7d: Randomly re-sort the satellites belonging to the i-th constellation among the endpoints of the inter-layer links in the j-th population in the total population PQ, connect them to the satellites of the i+1-th constellation in sequence according to the newly sorted satellite order, and update the j-th population to the new inter-layer link set;

[0043] S7e: Perform the maximum link weight matching operation on the satellites of the i-th layer and the i+1-th layer of the j-th population using the Hungarian algorithm, and update the j-th population to the new inter-layer link set;

[0044] S7f: Let the adjacency matrix of the inter-layer topology composed of the set of inter-layer links in the j-th population in PQ be adj i,i+1 , then the adjacency matrix of the entire network is And according to the first-order moment of the adjacency matrix statistics of the entire network <d j > and second-order moment Find the average path length of the entire network;

[0045] S7g: Select the minimum network average path length ψ from the clone population Q a The corresponding population P o , and P o Join the population P and delete the maximum average network path length ψ in P b The corresponding population P b ;

[0046] S7h:If ψ a ≤ψ, then ψ=ψ a , and it=it+1, jump to S7c; otherwise, end the loop and output the minimum network average path length ψ a The corresponding population P o , that is, the optimal inter-layer link set Φ=P o .

[0047] In one embodiment of the present invention, a population P in PQ is randomly selected. a As the crossover population, all other populations are combined with P by single-point crossover. a Crossover, including:

[0048] Randomly select population P a As the intersection point, mark it as g, and divide P a The population other than c , 1≤g≤300; for P c The first satellite to the g-th satellite of the s-th population and P a The first satellite in the gth satellite is exchanged to the gth satellite, where 1≤s≤149.

[0049] In one embodiment of the present invention, the S7e includes:

[0050] The top labels of all satellites in the i-th layer of the j-th population are set to the maximum value of the link weight of the corresponding constructed inter-layer links, and the top labels of all satellites in the i+1-th layer are set to 0. The Hungarian algorithm is used to find a perfect matching set so that the sum of the link weights of all inter-layer links is maximized. If a perfect matching set cannot be found, the top labels of satellites in the i-th layer are modified sequentially until a perfect matching set is found. The matching set is obtained and used as the new inter-layer link set of the j-th population.

[0051] In one embodiment of the present invention, the S7f includes:

[0052] S7f1: According to the inter-layer topology and intra-layer topology, the adjacency matrix of the entire network is obtained as And let the degree of the e-th satellite be deg e , then the first moment of the degree distribution is:

[0053] Among them, 1≤e≤N;

[0054] S7f2: Calculate the second moment of the degree distribution based on the first moment of the degree distribution:

[0055]

[0056] S7f3: Calculate the average path length of the entire network based on the first and second moments of the degree distribution:

[0057]

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] 1. The method of the present invention first constructs a feasible set of inter-layer links based on the conditions for constructing inter-satellite links. Secondly, the mapping relationship between the network topology transformation and the network transmission performance after adding the inter-layer link is analyzed, and the global ground business model and the current maximum sustainable duration of the inter-satellite link are constructed according to the geographical population distribution to determine the weight of the inter-satellite link, so as to establish an inter-layer link allocation model. Furthermore, the inter-layer link set is optimized in the feasible set of inter-layer links by combining the genetic algorithm and the maximum weight matching algorithm to obtain the optimized inter-layer link set. The present invention designs the inter-layer topology of a large-scale satellite network by constructing inter-layer links, and significantly improves the throughput of the large-scale multi-layer satellite network by optimizing the inter-layer topology structure, and effectively improves the service coverage capability for global non-uniform services.

[0060] 2. The present invention designs the inter-layer topology by constructing inter-layer links, and searches for the optimal inter-layer topology according to the changed topological characteristics of the entire network, namely, the degree distribution, and calculates the first-order moment and the second-order moment of the degree distribution to obtain the average number of hops in the network, thereby avoiding the exhaustive hop count statistics of all satellite node pairs in the entire network; constructs the link weight of the inter-layer link according to the sustainable time of the inter-layer link and the inter-layer link load for ground non-uniform services, so as to improve the service coverage capability of the satellite network for ground services and reduce the number of switching times of the inter-layer link; reduces the scale of the inter-layer link construction by constructing a feasible set of inter-layer links, and constructs the inter-layer link population by combining the genetic algorithm and the maximum weight matching algorithm, providing a set of inter-layer links with the minimum average path length of the entire network for the specified number of inter-layer link sets, thereby reducing the complexity of the inter-layer link construction problem from the exponential computational complexity to the polynomial level.

[0061] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a flow chart of a method for designing large-scale multi-layer constellation inter-layer links with enhanced service coverage capability provided by an embodiment of the present invention;

[0063] Figure 2 This is a schematic diagram of a network scenario for constructing a satellite inter-layer link provided by an embodiment of the present invention;

[0064] Figure 3 This is a flowchart for implementing a single-layer constellation adjacency matrix provided by an embodiment of the present invention;

[0065] Figure 4 This is a flowchart for implementing the construction of a multi-layer constellation inter-layer link provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0066] To further illustrate the technical means and effectiveness of the present invention in achieving its intended purpose, a large-scale multi-constellation inter-layer link design method with enhanced service coverage capability, proposed in accordance with the present invention, is described in detail below with reference to the accompanying drawings and specific embodiments.

[0067] The aforementioned and other technical contents, features, and effects of the present invention are clearly presented in the following detailed description of the specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a deeper and more specific understanding of the technical means and effects adopted by the present invention to achieve the intended purpose can be obtained. However, the accompanying drawings are provided for reference and illustration purposes only and are not intended to limit the technical solutions of the present invention.

[0068] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the article or device comprising the element.

[0069] This embodiment constructs a large-scale, multi-layer satellite network using satellite network parameters. This network includes a two-layer satellite constellation. A five-tuple of Kuiper parameters is designed for the single-layer constellation: number of orbital planes, number of satellites per orbit, phase factor, altitude, and orbital inclination. Furthermore, a mesh topology is designed by having each satellite in the single-layer constellation establish permanent inter-satellite links with two adjacent satellites in the same orbit, and two left and right inter-satellite links with two satellites in different orbits. A topological adjacency matrix is ​​generated for each layer. A feasible set of inter-layer links is constructed based on the physical construction principles of inter-satellite links, namely, satellite visibility, isotropy, and transmit power. The terrestrial services transmitted by each inter-satellite link are determined based on the ground area covered by the satellites. Terrestrial services are obtained by dividing the Earth's surface into 72 logical regions and collecting global network user data for each region. The link weight of each inter-layer link in the feasible set is calculated based on the inter-satellite link duration and link load, and an inter-layer link allocation model is established. The genetic algorithm and the maximum weight matching algorithm are combined to optimize the inter-layer link set in the inter-layer link feasible set, and the optimized inter-layer link set is obtained.

[0070] Specifically, see Figure 1 , Figure 1 This is a flow chart of a method for designing large-scale multi-layer constellation inter-layer links with enhanced service coverage, provided by an embodiment of the present invention. The method includes:

[0071] S1: Construct a large-scale multi-layer satellite network spanning T time slots, and obtain the coordinates of all satellites in the multi-layer satellite network in each time slot in geocentric coordinates.

[0072] In this embodiment, S1 includes:

[0073] S1a: Build a large-scale multi-layer satellite network.

[0074] See Figure 2 , Figure 2 This is a schematic diagram of a network scenario for constructing inter-satellite layer links provided by an embodiment of the present invention. Taking two layers of the Kuiper constellation as an example, the corresponding number of orbital planes and the number of satellites in one orbit are P1=28, S1=28, P2=36, and S2=36, respectively, where P1 and P2 represent the number of orbits in the first and second layers, respectively, and S1 and S2 represent the number of satellites per orbit in the first and second layers, respectively. The two-layer trajectory of the Kuiper constellation can be exported using STK software for a total duration of 2 hours, with each time slot being 1 second, to obtain the longitude, latitude, and altitude of each time slot, where N=N1+N2=28×28+36×36, where N1 represents the total number of satellites in all orbits of the first layer, N2 represents the total number of satellites in all orbits of the second layer, and N represents the total number of satellites in the first and second layers.

[0075] S1b: Enter constellation parameters into the STK (Satellite Tool Kit) software and use the constellation parameters to calculate the longitude, latitude, and altitude data of each layer of satellites, recorded as Lon, Lat, and Alt respectively. The constellation parameters include the number of orbital planes, the number of satellites per orbit, the phase factor, the altitude, and the orbital inclination.

[0076] S1c: Using the longitude, latitude and altitude of each satellite in each layer in each time slot, the position coordinates of each satellite in each time slot in the geocentric coordinate system are obtained.

[0077] Specifically, the longitude, latitude, and altitude of the i-th satellite are converted from the geographic coordinate system to the geocentric coordinate system to obtain the position coordinates of the i-th satellite in the geocentric coordinate system:

[0078] x i =Alt i *cos(Lat i )*sin(Lon i ),

[0079] y i =Alt i *sin(Lat i ),

[0080] z i =Alt i *cos(Lat i )*cos(Lon i ),

[0081] Among them, 1≤i≤N1+N2, x i ,y i , z i The position coordinates of the i-th satellite in the geocentric coordinate system, Lon i ,Lat i ,Alt i denote the longitude, latitude and altitude of the i-th satellite respectively.

[0082] S1d: Use the expression in step S1c to obtain the coordinates of all satellites in geocentric coordinates, denoted as G.

[0083] S2: Construct an adjacency matrix of each constellation in the multi-layer satellite network.

[0084] In this embodiment, the adjacency matrix adj of the i-th constellation is constructed. i , where 1≤i≤L=2, and L represents the total number of constellation layers. Figure 3 , Figure 3This is a flowchart for implementing a single-layer constellation adjacency matrix according to an embodiment of the present invention. The adjacency matrix of a single-layer constellation according to this embodiment is mainly divided into three steps, including: establishing a co-orbit link, establishing a different-orbit link, and constructing an adjacency matrix.

[0085] Specifically, step S2 of this embodiment includes:

[0086] S2a: Let adj i As a two-dimensional matrix, construct a co-orbit link. For the s-th satellite in the p-th orbit of the i-th constellation, we have:

[0087] adj i ((p-1)·S i +s,(p-1)·S i +s+1)=1

[0088] adj i ((p-1)·S i +s+1,(p-1)·S i +s)=1

[0089] Among them, S i Indicates the number of satellites per orbit in the i-th layer, 1≤p≤P i , P i Indicates the number of tracks in the i-th layer, 1≤s≤S i -1;

[0090] S2b: The Sth on the pth orbit of the i-th constellation i The last satellite is connected to the first satellite, and we get:

[0091] adj i ((p-1)·S i +S i ,(p-1)·S i +1)=1

[0092] adj i ((p-1)·S i +1,(p-1)·S i +S i )=1

[0093] S2c: Constructing a different-orbit link. For the ss-th satellite in the pp-th orbit of the i-th constellation, we have:

[0094] adj i ((pp-1)·S i +ss,pp·S i +ss)=1

[0095] adj i (pp·S i+ss,(pp-1)·S i +ss)=1

[0096] Among them, 1≤pp≤P i -1, 1≤ss≤S i .

[0097] S3: Construct a feasible set of satellite links between two adjacent layers in the multi-layer satellite network in each time slot. Specifically, construct a feasible set F of satellite links between the i-th layer and the i+1-th layer. i,i+1 , including the following steps:

[0098] S3a: Let f(c,g) represent whether the cth satellite belonging to the i-th layer and the gth satellite belonging to the i+1-th layer meet the visibility condition, and calculate the maximum visible Euclidean distance d between the satellites in the two-layer constellation. max :

[0099]

[0100] Wherein, H1=590km represents the orbital altitude of the i-th layer satellite constellation, H2=610km represents the orbital altitude of the i+1-th layer satellite constellation, Re=6371km represents the radius of the Earth, ro=50km represents the atmospheric altitude, 1≤c≤N1, 1≤g≤N2, N1 represents the total number of satellites in all orbits of the i-th layer, and N2 represents the total number of satellites in all orbits of the i+1-th layer.

[0101] In this embodiment, the total number of constellation layers is L=2. Therefore, correspondingly, H1 represents the orbital altitude of the first-layer satellite constellation, H2 represents the orbital altitude of the second-layer satellite constellation, N1 represents the total number of satellites on all orbits of the first layer, and N2 represents the total number of satellites on all orbits of the second layer.

[0102] S3b: Calculate the Euclidean distance between the cth satellite in the i-th layer and the gth satellite in the i+1-th layer If d c,g <d max , then f(c,g)=1, otherwise, f(c,g)=0, where (x c ,y c ,z c ) represents the position coordinates of the cth satellite in the i-th layer, (x g ,y g ,z g ) represents the position coordinates of the g-th satellite in the i+1-th layer;

[0103] S3c: Using steps S3a and S3b, determine whether all satellite node pairs have visual conditions, and store f(c, g) in F i,i+1 , obtain the satellite link feasible set F i,i+1.

[0104] S4: Construct a non-uniform ground traffic model based on geographic population distribution. The earth's surface is divided into 72 logical regions. The load of each region is obtained according to global network user data. Let the traffic density of the xth region be ρ x .

[0105] S5: Calculate the weight of the inter-layer link formed by two adjacent layers of satellites in each time slot in the satellite link feasible set according to the link duration and link load.

[0106] Specifically, step S5 of this embodiment includes:

[0107] S51: Let y i,i+1 (u,v) indicates whether the u-th satellite from the i-th layer forms an inter-layer link with the v-th satellite from the i+1-th layer. If so, y i,i+1 (u,v)=1, if not, then y i,i+1 (u,v)=0;

[0108] S52: Order represents the total duration of the inter-layer link formed by the u-th satellite in the i-th layer and the v-th satellite in the i+1-th layer in the t-th time slot, represents the remaining time of the inter-layer link formed by the u-th satellite in the i-th layer and the v-th satellite in the i+1-th layer in the t-th time slot, and the time weight of the current inter-layer link is obtained as:

[0109]

[0110] S53: Let the traffic density of the coverage area of ​​the u-th satellite in the i-th layer in the x-th logical area be Map the current satellite traffic density to the corresponding inter-layer link load, and the inter-layer link load is recorded as The load weight of the corresponding inter-layer link is Among them, ρ x represents the traffic density of the xth logical area, represents the number of satellites in the i-th layer of the x-th logical region, and max(δ) represents the number of all The maximum value in the set δ;

[0111] S54: Obtain the comprehensive weight of the inter-layer link according to the time weight of the inter-layer link and the load weight of the inter-layer link:

[0112]

[0113] S6: Establish an inter-layer link allocation model according to the weights of the inter-layer links.

[0114] Specifically, an inter-layer link allocation model is established:

[0115]

[0116]

[0117]

[0118] Among them, ψ i,i+1 represents the average path length of the i-th layer and the i+1-th layer network, constraint (1) represents maximizing the link weight of the inter-layer link in each time slot, constraint (2) represents that the satellite of the i-th layer builds an inter-layer link at most once in a time slot, and constraint (3) represents that the satellite of the i+1-th layer builds an inter-layer link at most once in a time slot.

[0119] S7: Utilizing the inter-layer link allocation model, in combination with a genetic algorithm and a maximum weight matching algorithm, the inter-layer link set is optimized in the satellite link feasible set to obtain an optimized inter-layer link set.

[0120] See Figure 4 , Figure 4 This is a flowchart for implementing the construction of a multi-layer constellation inter-layer link provided by an embodiment of the present invention. The specific steps are as follows:

[0121] S7a: Let k = 300, randomly construct a population P of m inter-layer links, and each population contains 300 non-repeating inter-layer links connecting k satellites randomly selected from the first layer and k satellites randomly selected from the second layer. Let it be the number of iterations, initialize it = 0, and let ψ be the initial average network path length, ψ = 1000, and m = 100.

[0122] S7b: Copy all inter-layer links of the jth population in the population P to generate 50 clone populations Q, with a total population size of 150. The total population is recorded as PQ, and set p c is the crossover probability, p x is the mutation probability, and p c +p x =1, n=50, p c =0.6, p x =0.4.

[0123] S7c: Let λ be the probability of random generation under the current number of iterations, and 0<λ<1. If λ <p c , then randomly select the population P in PQ a As the crossover population, all other populations are combined with P by single-point crossover. a Crossover; if λ≥p c , then jump to S7d.

[0124] Specifically, a population P is randomly selected a As the intersection point, record it as g, let P a '=P a , and divide P a The population other than c , where 1≤g≤300; for P c The first satellite to the g-th satellite of the s-th population and P a The first satellite in the gth satellite is exchanged to the gth satellite, where 1≤s≤149.

[0125] S7d: Randomly re-sort the satellites belonging to the i-th constellation among the endpoints of the inter-layer links in the j-th population in the total population PQ, connect them to the satellites of the i+1-th constellation in sequence according to the newly sorted satellite order, and update the j-th population to the new inter-layer link set;

[0126] S7e: Perform the maximum link weight matching operation on the satellites of the i-th layer and the i+1-th layer of the j-th population using the Hungarian algorithm, and update the j-th population to the new inter-layer link set;

[0127] Specifically, the top labels of all satellites in the i-th layer in the j-th population are set to the maximum value of the link weight of the corresponding constructed inter-layer links, and the top labels of all satellites in the i+1-th layer are set to 0; the Hungarian algorithm is used to find a perfect matching set so that the sum of the link weights of all inter-layer links is maximized. If a perfect matching set cannot be found, the top labels of satellites in the i-th layer are modified in sequence until a perfect matching set is found; the matching set is obtained and used as the new inter-layer link set of the j-th population.

[0128] S7f: Let the adjacency matrix of the inter-layer topology composed of the set of inter-layer links in the j-th population in PQ be adj i,i+1 , then the adjacency matrix of the entire network is And according to the first-order moment of the adjacency matrix statistics of the entire network <d j > and second-order moment Find the average path length of the entire network.

[0129] Specifically, step S7f of this embodiment includes:

[0130] S7f1: According to the inter-layer topology and intra-layer topology, the adjacency matrix of the entire network is obtained as And let the degree of the e-th satellite be deg e , then the first moment of the degree distribution is:

[0131] Among them, 1≤e≤N;

[0132] S7f2: Calculate the second moment of the degree distribution based on the first moment of the degree distribution:

[0133]

[0134] S7f3: Calculate the average path length of the entire network based on the first and second moments of the degree distribution:

[0135]

[0136] S7g: Select the minimum network average path length ψ from the clone population Q a The corresponding population P o , and P o Join the population P and delete the maximum average network path length ψ in P b The corresponding population P b ;

[0137] S7h:If ψ a ≤ψ, then ψ=ψ a , and it=it+1, jump to S7c; otherwise, end the loop and output the minimum network average path length ψ a The corresponding population P o , that is, the optimal inter-layer link set Φ=P o .

[0138] An embodiment of the present invention proposes a method for designing inter-layer links for a large-scale, multi-layer constellation with enhanced service coverage. The method determines the weight of the inter-satellite link by constructing a global ground service model based on geographic population distribution and weighting the normalized weight of the current maximum sustainable duration of the inter-satellite link. A maximum weighted algorithm is used to maximize network service coverage and link stability, thereby reducing inter-layer link switching and improving network transmission capacity. A mapping relationship between network performance after time-varying network topology transformation is constructed, and statistical characteristics after adding inter-layer links, namely the first-order moment and second-order moment of the degree distribution, are obtained to estimate the average path length of the entire network, avoiding the exhaustive hop count statistics of all satellite node pairs in the entire network. By combining a genetic algorithm and constructing a local inter-layer link population, a set of inter-layer links with the minimum average path length of the entire network can be provided for any number of inter-layer link sets, effectively reducing the complexity of the inter-layer link construction problem from exponential computational complexity to polynomial level, making the method applicable to large-scale, multi-layer satellite networks.

[0139] The inter-layer link design method of the present invention determines the weight of the inter-satellite link by analyzing the mapping relationship between the network topology transformation after adding the inter-layer link and the network transmission performance based on the conditions for building the inter-satellite link. It also constructs a global ground service model and the current maximum sustainable duration of the inter-satellite link based on the geographical population distribution, thereby establishing an inter-layer link allocation model. The method then combines the genetic algorithm and the maximum weight matching algorithm to optimize the inter-layer link set in the feasible set of inter-layer links to obtain an optimized inter-layer link set. The present invention constructs inter-layer links and designs the inter-layer topology of a large-scale satellite network. By optimizing the inter-layer topology structure, the throughput of the large-scale multi-layer satellite network is significantly improved, effectively enhancing the service coverage capability for global non-uniform services.

[0140] Another embodiment of the present invention provides a storage medium storing a computer program configured to execute the steps of the method for designing inter-layer links between multi-layer constellations with enhanced service coverage described in the above embodiments. Another aspect of the present invention provides an electronic device comprising a memory and a processor, wherein the memory stores a computer program configured to execute the steps of the method for designing inter-layer links between multi-layer constellations with enhanced service coverage described in the above embodiments when the processor invokes the computer program in the memory. Specifically, the integrated module implemented as a software function module can be stored in a computer-readable storage medium. The software function module is stored in a storage medium and includes instructions for causing an electronic device (such as a personal computer, server, or network device) or a processor to execute some of the steps of the method described in various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0141] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for designing inter-layer links between multi-layer constellations with enhanced service coverage, characterized in that: include: S1: Construct a large-scale multi-layer satellite network spanning T time slots, and obtain the coordinates of all satellites in the multi-layer satellite network in each time slot in geocentric coordinates; S2: constructing an adjacency matrix of each constellation in the multi-layer satellite network; S3: constructing a feasible set of satellite links between two adjacent layers in the multi-layer satellite network in each time slot; S4: Construct a ground non-uniform traffic model based on geographic population distribution, dividing the Earth's surface into multiple logical regions. The load of each logical region is obtained based on global network user data. S5: Calculating the weight of the inter-layer link formed by two adjacent layers of satellites in each time slot in the satellite link feasible set according to the link duration and the link load; S6: Establishing an inter-layer link allocation model according to the weight of the inter-layer link; S7: optimizing the inter-layer link set in the satellite link feasible set using the inter-layer link allocation model to obtain an optimized inter-layer link set; The S5 includes: S51: Order Indicates that it comes from Layer Is the satellite from Layer Satellites form an inter-layer link. If so, then , if not, then ; S52: Order Indicates the Layer Satellite and Layer The inter-layer link composed of satellites is The total duration of the time slots, Indicates the Layer Satellite and Layer The inter-layer link composed of satellites is The remaining time of the time slot is obtained, and the time weight of the current inter-layer link is: ； S53: Order Time slot Tier The coverage area of ​​the satellite is The traffic density of a logical area is , mapping the current satellite traffic density to the corresponding inter-layer link load, then the inter-layer link load is recorded as , the load weight of the corresponding inter-layer link is ,in, Indicates the The traffic density of each logical area, Indicates that it is located at The first logical area The number of satellites in the layer, Indicates all Composed of a collection The maximum value in ; S54: Obtain the comprehensive weight of the inter-layer link according to the time weight of the inter-layer link and the load weight of the inter-layer link: ； The S7 includes: S7a: Let the number of inter-layer chains be , and randomly construct The population of inter-layer links , and each population contains Layer randomly selected Satellites and Layer randomly selected Satellites connected non-repeated inter-layer links, let is the number of iterations, initialize , and let is the average path length of the initial network; S7b: Replication population Middle All inter-layer links of the population generate clonal populations, denoted as , the total population The total population is recorded as , and set is the crossover probability, is the mutation probability, and ; S7c: Order is the probability of random generation under the current number of iterations, and ,like , then randomly select Populations in As a crossover population, all other populations are crossed with Cross; if , then jump to S7d; S7d: For the total population Middle The endpoints of the inter-layer links in the population belong to The satellites of the first constellation are randomly re-arranged and connected to the satellites of the layer constellation and the The population is updated to the new set of inter-layer links; S7e: The first Satellites on the first floor and The satellites in the first layer use the Hungarian algorithm to perform the maximum link weight matching operation and The population is updated to the new set of inter-layer links; S7f: Command by Middle The adjacency matrix of the inter-layer topology composed of the inter-layer link set in the population is recorded as , then the adjacency matrix of the entire network is , and according to the first-order moment of the adjacency matrix statistics of the entire network and second-order moment , find the average path length of the entire network; S7g: from clonal populations Select the minimum network average path length Corresponding population , and Join the population , and delete The maximum average path length of the network Corresponding population ; S7h: If ,but ,and , jump to S7c; otherwise, end the loop and output the minimum network average path length Corresponding population , that is, the optimal inter-layer link set .

2. The method for designing multi-layer constellation inter-layer links with enhanced service coverage capability according to claim 1, characterized in that: Said S1 comprises: S1a: Build a large-scale multi-layer satellite network, which lasts for T time slots. ; S1b: Obtain constellation parameters and use the constellation parameters to calculate the longitude, latitude and altitude data information of each satellite layer in each time slot; S1c: Using the longitude, latitude and altitude of each satellite in each layer in each time slot, the position coordinates of each satellite in each time slot in the geocentric coordinate system are obtained.

3. The method for designing multi-layer constellation inter-layer links with enhanced service coverage capability according to claim 2, characterized in that: The S3 includes: S3a: Order Indicates that it belongs to Layer Satellites belonging to Layer Whether the satellites meet the visibility conditions and calculate the maximum visible Euclidean distance of the satellites in the two-layer constellation : in, Indicates the The orbital altitude of the satellite constellation, Indicates the The orbital altitude of the satellite constellation, represents the radius of the Earth, represents the altitude of the atmosphere, , , Indicates the The total number of satellites in all orbits of the layer, Indicates the The total number of satellites in all orbits of the layer; S3b: Calculate the Layer Satellite and Layer Euclidean distance between satellites ,like ,but =1, otherwise, ,in,( , , ) indicates the Layer The position coordinates of the satellites, ( , , ) indicates the Layer Position coordinates of satellites; S3c: Use steps S3a and S3b to determine whether all satellite node pairs have visual conditions, and Deposit , obtain the feasible set of satellite links .

4. The method for designing multi-layer constellation inter-layer links with enhanced service coverage capability according to claim 3, wherein: The expression of the inter-layer link allocation model is: in, Indicates the Layer and The average path length of the layer network, constraint (1) represents maximizing the link weight of the inter-layer link in each time slot, and constraint (2) represents the The satellites of the first layer can build an inter-layer link at most once in a time slot. Constraint (3) means that Satellites in a layer establish an inter-layer link at most once in a time slot.

5. The method for designing multi-layer constellation inter-layer links with enhanced service coverage capability according to claim 4, characterized in that: Random selection Populations in As a crossover population, all other populations are crossed with Crossover, including: Randomly select a population As the intersection point, we can record it as , and remove Populations other than , ;right The first The first satellite of the population to the Satellites and The first satellite to the Satellites are exchanged, among which, .

6. The method for designing multi-layer constellation inter-layer links with enhanced service coverage capability according to claim 5, characterized in that: The S7e includes: The first In the population The top labels of all satellites in the layer are set to the maximum value of the link weights of the corresponding inter-layer links. The top marks of all satellites in the layer are set to 0; the Hungarian algorithm is used to find a perfect matching set so that the sum of the link weights of all inter-layer links is maximized. If a perfect matching set cannot be found, the first The top mark of the satellite in the layer is obtained until a perfect matching set is found; the matching set is obtained and used as the first A new set of inter-layer links for a population.

7. The method for designing multi-layer constellation inter-layer links with enhanced service coverage capability according to claim 6, wherein: The S7f includes: S7f1: According to the inter-layer topology and intra-layer topology, the adjacency matrix of the entire network is obtained as , and order The satellite's degree is , then the first moment of the degree distribution is: ,in, ; S7f2: Calculate the second moment of the degree distribution based on the first moment of the degree distribution: ； S7f3: Calculate the average path length of the entire network based on the first and second moments of the degree distribution: 。

Images