Interference mitigation method for implementing spatial domain frequency plan based on tracking area coding

Abstract

The invention relates to an interference mitigation method for implementing a spatial domain frequency plan based on tracking area coding, and belongs to the technical field of low-orbit satellite communication co-frequency interference suppression. The method comprises the following specific steps: (1) acquiring interference-to-noise ratio I / N distribution of a satellite-to-ground link of a user in a required hot spot area; (2) setting a user satellite-ground link I / N optimization target; (3) carrying out region regularization on the required hot spot region; (4) setting ground partition parameters; (5) setting subarea parameters of the visual area of the ground station; (6) forming an air-ground joint frequency assignment scheme; (7) judging whether I / N reaches an expected target or not, and if not, repeating the steps (4)-(6); if yes, optimization is completed, and a division strategy is determined. According to the invention, the dynamic allocation and optimization of frequency resources can be realized, and the same-frequency interference when the terminal accesses the satellite is obviously reduced, so that the system capacity and the communication quality are improved.

Description

Technical Field

[0001] This invention belongs to the field of co-frequency interference suppression in low-orbit satellite communication, and relates to an interference mitigation method based on tracking area coding for implementing spatial frequency planning. Background Technology

[0002] With the continuous development of mobile communication technology, the surge in the number of mobile users, and the increasing variety of services, wireless spectrum resources are becoming increasingly scarce. Against this backdrop, how to efficiently utilize spectrum resources, improve system capacity, and ensure communication quality has become one of the core issues that current wireless communication systems urgently need to address. This is especially true in low-Earth orbit satellite communication systems, where frequency resource management faces even greater challenges due to the high dynamic characteristics of rapid satellite movement and the widespread distribution of terminals.

[0003] Traditional wireless communication systems typically employ fixed or semi-dynamic frequency planning methods. These methods often involve static allocation based on estimated coverage areas, user distribution, and interference models at the initial design stage. While this approach can achieve a certain degree of interference control initially, it often reveals numerous shortcomings when facing complex and ever-changing real-world network environments. Specific problems manifest in the following aspects:

[0004] (1) Low spectrum resource utilization

[0005] Traditional static frequency planning ignores the dynamic changes in user behavior and traffic demands. Many reserved frequency resources remain underutilized or idle during actual operation, leading to wasted spectrum resources. Furthermore, uneven frequency allocation in certain local areas can cause resource shortages, resulting in severe interference problems. In low-Earth orbit satellite communications, where satellite coverage areas change rapidly over time, the drawbacks of this static allocation are particularly pronounced, making it difficult to meet the dynamic frequency demands of hotspot areas.

[0006] (2) Limited interference suppression effect

[0007] When users are moving at high speeds or network load fluctuates dramatically, fixed-frequency planning strategies cannot respond in a timely manner, making it difficult to effectively address co-channel interference caused by frequent handovers or signal overlap. Furthermore, wireless signals are affected by multipath effects and shadowing fading during propagation, further limiting the interference suppression capabilities of traditional methods. For low-Earth orbit satellite communication systems, co-channel interference is particularly prominent when terminals switch between different satellite coverage areas, directly impacting communication quality.

[0008] (3) Insufficient information based on regional division

[0009] While some current communication systems employ area division to aid frequency planning, they lack refined management of interference within and between areas. Tracking Area Code (TAC), an identification technology used to distinguish different areas within a network, effectively reflects network area division, user aggregation, and handover behavior. However, traditional frequency planning methods often fail to fully utilize TAC information for dynamic adjustments and interference avoidance, resulting in persistent system interference problems in high-density or complex scenarios. In low-Earth orbit satellite communications, the failure to integrate TAC technology for dynamic frequency management further exacerbates the difficulty of resource allocation and interference control.

[0010] (4) Insufficient adaptability and real-time performance

[0011] Existing interference avoidance strategies largely rely on fixed rules or simple feedback adjustments, lacking the ability to dynamically adjust frequency allocation based on real-time data. In practical applications, network environments change rapidly, with user locations, loads, and interference conditions constantly evolving. Traditional methods struggle to meet the demands of real-time adjustments and cannot quickly implement effective measures to suppress interference surges. For low-Earth orbit satellite communication systems, the rapid movement of satellites and the high density of terminal access place even higher demands on real-time performance, and the shortcomings of traditional methods significantly limit the reliability and efficiency of the system. Summary of the Invention

[0012] The technical problem solved by this invention is to overcome the shortcomings of the prior art. This invention provides an interference mitigation method for implementing spatial frequency planning based on tracking region coding.

[0013] The solution of this invention is: an interference mitigation method based on tracking region coding for implementing spatial frequency planning, comprising the following steps:

[0014] (1) Obtain the CCDF curves of the interference-to-noise ratio (I / N) distribution of satellite-to-ground links for users in demand hotspot areas;

[0015] (2) Set user satellite-to-ground link I / N limits;

[0016] (3) Implement regional regularization for hot demand areas, including ground regularization zoning of hot demand areas and visible airspace zoning of satellite ground stations;

[0017] (4) Set the ground regularization partitioning parameters for hotspot areas;

[0018] (5) Set the visible airspace partitioning parameters for the satellite ground station;

[0019] (6) Based on the parameters set in steps (4) and (5), a joint air-ground frequency assignment scheme is formed;

[0020] (7) Determine whether the interference-to-noise ratio I / N has reached the expected optimization target based on the criterion conditions; if it is satisfied, then complete the optimization and determine the partitioning strategy; if it is not satisfied, repeat steps (4) to (6) until the optimization target is met.

[0021] Furthermore, the ground regularization partitioning of the hotspot area described in step (3) includes quadrilateral grid partitioning and hexagonal grid partitioning.

[0022] Furthermore, the steps for setting the parameters for ground regularization partitioning of hotspot areas are as follows:

[0023] 1) Divide the ground of a hotspot area into a grid of n rows and m columns;

[0024] 2) For the regularized n-row m-column ground cell coding, each cell is uniquely identified by the row number a and the column number b; where a takes values ​​from 0 to n-1, and b takes values ​​from 0 to m-1;

[0025] 3) Set the frequency reuse factor i for the ground cell;

[0026] 4) Assigning terrestrial cell frequency group F cell ={F1,F2,...,F i The assignment formula is as follows:

[0027] F i =F{[(a+b)mod i]+1}

[0028] a is the row number of the ground cell, b is the column number of the ground cell, F i This refers to the frequency allocated to the ground cells.

[0029] Furthermore, the initial values ​​of the n rows and m columns, and the initial value of the frequency reuse factor i, are all randomly selected.

[0030] Furthermore, the regularized partitioning of the visible airspace of the satellite ground station described in step (3) is a strip-shaped arrangement with equal arcs along the direction of due south-zenith-due north.

[0031] Furthermore, the regularization partitioning parameters for setting the visible spatial domain of the satellite ground station include:

[0032] Set the number of cells j in the visible airspace of the ground station, and set the percentage of overlapping frequencies in the airspace frequency bands;

[0033] Divide the airspace visible to the ground station into cells c along an equal arc from due south to zenith to due north, and determine the cell boundary points of the airspace;

[0034] The airspace boundary point y of the c-th cell c The calculation formula is:

[0035] y c=-90+c×180÷j

[0036] Using the airspace boundary point as the endpoint, and perpendicular to the due south-zenith-due north direction, the airspace boundary line is delineated and confirmed, expressed as:

[0037]

[0038] and (x) c y c Convert Cartesian coordinates to polar coordinates;

[0039] Assigning airspace cell frequency group F cell ={f1,f2,...f j The assignment formula is as follows:

[0040] f j =f[(c mod j)+1]

[0041] c takes values ​​from 0 to j-1; f j This refers to the frequency assigned to the airspace cell.

[0042] Furthermore, the spatial cell frequency group {f1,f2,...f j} refers to the frequency group of the ground cell {F1,F2,...,F} i Further division of each frequency band in}, where i is the frequency reuse factor of the ground cell.

[0043] Furthermore, the initial values ​​for the number of cells j in the visible airspace of the ground station and the percentage of overlapping frequencies in the airspace frequency bands are randomly selected.

[0044] Furthermore, in step (6), the air-to-ground joint frequency assignment f = {f1, f2, ..., f...} j ,...f i×j The formula is as follows:

[0045] f i×j = f{[(a+b)mod i]×j+c+1}

[0046] f i×j The frequency of the visible airspace cells is ultimately assigned to specific ground cell users; a is the row number of the ground cell, b is the column number of the ground cell, c is the row number of the airspace cell, and j is the number of cells in the visible airspace of the ground station.

[0047] Furthermore, the criterion in step (7) is as follows: if the CCDF curve of the user's satellite-to-ground link interference noise ratio (I / N) is greater than the I / N limit, then the expected target has not been achieved; if the CCDF curve of the user's satellite-to-ground link interference noise ratio (I / N) is smaller than the I / N limit, then the expected target has been achieved.

[0048] The advantages of this invention compared to the prior art are:

[0049] (1) This invention achieves dynamic allocation and adjustment of frequency resources according to user needs and interference conditions by tracking area coding of hot spots, thereby improving the adaptability and flexibility of the system and meeting the dynamic frequency requirements of hot spots.

[0050] (2) This invention effectively mitigates co-channel interference and improves communication quality by using tracking area coding technology and spatial cell division.

[0051] (3) By setting parameters such as the number of tracking cells in hotspot areas, frequency reuse factor, and number of spatial cells, this invention provides more space for strategy implementation, optimizes frequency resource utilization, reduces spectrum resource waste, and improves system capacity.

[0052] (4) The present invention can detect and actively avoid interference in real time, which meets the needs of real-time adjustment in practical applications and improves the reliability and efficiency of the system. Attached Figure Description

[0053] Figure 1 This is a flowchart illustrating the implementation steps of the method of the present invention;

[0054] Figure 2 A schematic diagram illustrating the division of ground hotspot areas and the visible airspace of ground stations;

[0055] Figure 3 A schematic diagram showing the division of ground-level residential areas in hotspot regions;

[0056] Figure 4 I / N distribution map of hotspot region A in constellation;

[0057] Figure 5 Assigning terrestrial cell frequency groups for hotspot areas to constellation A;

[0058] Figure 6 Diagram showing the relationship between the frequency groups of terrestrial cells and space cells in constellation A;

[0059] Figure 7 Satellites within the line of sight of the Constellation A ground station (30.5°N, 0.5°E);

[0060] Figure 8 The azimuth and elevation angles are from the perspective of the A constellation ground station (30.5°N, 0.5°E).

[0061] Figure 9 The final frequency assignment is from the perspective of the A constellation ground station (30.5°N, 0.5°E).

[0062] Figure 10Satellites within the line of sight of the Constellation A ground station (30.5°N, 1.5°E);

[0063] Figure 11 The azimuth and elevation angles are from the perspective of the A constellation ground station (30.5°N, 1.5°E).

[0064] Figure 12 The final frequency assignment is from the perspective of the A constellation ground station (30.5°N, 1.5°E).

[0065] Figure 13 Satellites within the line of sight of the Constellation A ground station (30.5°N, 2.5°E);

[0066] Figure 14 The azimuth and elevation angles are from the perspective of the A constellation ground station (30.5°N, 2.5°E).

[0067] Figure 15 The final frequency assignment is from the perspective of the A constellation ground station (30.5°N, 2.5°E).

[0068] Figure 16 Satellites within the line of sight of the Constellation A ground station (30.5°N, 3.5°E);

[0069] Figure 17 The azimuth and elevation angles are from the perspective of the A constellation ground station (30.5°N, 3.5°E).

[0070] Figure 18 The final frequency assignment is from the perspective of the A constellation ground station (30.5°N, 3.5°E).

[0071] Figure 19 Satellites within the line of sight of the Constellation A ground station (31.5°N, 0.5°E);

[0072] Figure 20 The azimuth and elevation angles are from the perspective of the A constellation ground station (31.5°N, 0.5°E).

[0073] Figure 21 The final frequency assignment is from the perspective of the A constellation ground station (31.5°N, 0.5°E).

[0074] Figure 22 Comparison chart before and after I / N optimization for constellation A;

[0075] Figure 23 I / N distribution map of hotspot region B in constellation;

[0076] Figure 24 Assigning hotspot area terrestrial cell frequency groups to constellation B;

[0077] Figure 25 The relationship between the frequency group of constellation B cell and the frequency group of space cell;

[0078] Figure 26 Satellites within the line of sight of the constellation B ground station (30.5°N, 0.5°E);

[0079] Figure 27 The azimuth and elevation angles are from the perspective of the constellation B ground station (30.5°N, 0.5°E).

[0080] Figure 28 The final frequency assignment is given from the perspective of the constellation B ground station (30.5°N, 0.5°E).

[0081] Figure 29 Satellites within the line of sight of the constellation B ground station (30.5°N, 1.5°E);

[0082] Figure 30 The azimuth and elevation angles are from the perspective of the constellation B ground station (30.5°N, 1.5°E).

[0083] Figure 31 The final frequency assignment is given from the perspective of the constellation B ground station (30.5°N, 1.5°E).

[0084] Figure 32 Satellites within the line of sight of the constellation B ground station (30.5°N, 2.5°E);

[0085] Figure 33 The azimuth and elevation angles are from the perspective of the constellation B ground station (30.5°N, 2.5°E).

[0086] Figure 34 The final frequency assignment is given from the perspective of the constellation B ground station (30.5°N, 2.5°E).

[0087] Figure 35 Satellites within the line of sight of the constellation B ground station (30.5°N, 3.5°E);

[0088] Figure 36 The azimuth and elevation angles are from the perspective of the constellation B ground station (30.5°N, 3.5°E).

[0089] Figure 37 The final frequency assignment is from the perspective of the constellation B ground station (30.5°N, 3.5°E).

[0090] Figure 38 Satellites within the line of sight of the constellation B ground station (31.5°N, 0.5°E);

[0091] Figure 39The azimuth and elevation angles are from the perspective of the constellation B ground station (31.5°N, 0.5°E).

[0092] Figure 40 The final frequency assignment is given from the perspective of the constellation B ground station (31.5°N, 0.5°E).

[0093] Figure 41 A comparison chart showing the I / N of constellation B before and after the first optimization;

[0094] Figure 42 The relationship between the frequency groups of terrestrial cells and space cells in constellation B;

[0095] Figure 43 A comparison chart showing the I / N optimization before and after for constellation B. Detailed Implementation

[0096] The present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments.

[0097] like Figure 1 As shown, the specific steps of an interference mitigation method based on tracking region coding for implementing spatial frequency planning are as follows:

[0098] (1) Obtain the I / N distribution of the satellite-to-ground link interference ratio of users in the hot demand area, that is, obtain the current status of the satellite-to-ground link in the target area, and provide basic data for the optimization process.

[0099] (2) Set the user satellite-to-ground link I / N optimization target to establish the target for the subsequent optimization process.

[0100] (3) Implement regional regularization for areas with high demand, that is, divide geographical areas into regular grids. For example... Figure 2 The diagram shows the ground-based regularized zoning of hotspot areas and the visible airspace zoning of satellite ground stations. The visible airspace of any ground station, i.e., the area with an elevation angle greater than the minimum communication elevation angle, is divided into cell units along a north-south direction. These cell units are arranged closely together, as shown below. Figure 3 The example shown is that the spatial regions are arranged in a strip shape. The azimuth angle is 0° for due north, 90° for due east, and 180° for due south. The polar axis length represents the range of elevation angles. The center point of the coordinate system is directly above the ground station, i.e., at an elevation angle of 90°.

[0101] To divide a polygonal region of land into n rows and m columns, the following steps and expressions can be used:

[0102] 1) Determine the circumscribed rectangle: Calculate the minimum circumscribed rectangle of the polygon and obtain its lower left corner (x, y). min ,y min ) and the top right corner (x max ,y max)coordinate.

[0103] 2) Calculate cell size:

[0104] Cell width: Δx = (x max -x min ) / m;

[0105] Cell height: Δy = (y max -y min ) / n;

[0106] 3) Define cell indexes: Each cell is uniquely identified by row number a (0 to n-1) and column number b (0 to m-1).

[0107] 4) Cell coordinate range:

[0108] cell bottom left corner: [x min +(b)Δx,y min +(a)Δy]

[0109] Top right corner of cell: (x min +(b+1)Δx,y min +(a+1)Δy)

[0110] (4) For the regularized n-row m-column polygon region encoding, each cell is uniquely identified by row number a (0 to n-1) and column number b (0 to m-1) to form a unique ground cell encoding identifier (a, b) for the hotspot region.

[0111] (5) Set the frequency reuse factor i for ground cells.

[0112] (6) Assigning ground cell frequency groups {F1,F2,...,F...} i Based on the terrestrial cell code and frequency reuse factor, frequency groups are assigned to various terrestrial cells. The assignment formula is as follows:

[0113] F cell =F{[(a+b)mod i]+1}

[0114] a and b are the row and column numbers respectively, F cell This refers to the frequency group assigned to the ground cell.

[0115] Steps (4) to (6) above are the steps for setting ground zoning parameters.

[0116] (7) Set the number of cells j in the visible airspace of the ground station.

[0117] (8) Divide the airspace into equal arcs along the due south and due north directions. First, divide the airspace into equal arcs along the due south-zenith-due north direction to determine the boundary points of the airspace cells.

[0118] The airspace boundary point y of the c-th cell c The calculation formula is:

[0119] y c =-90+c×180÷j

[0120] Secondly, using the airspace boundary point as the endpoint, and perpendicular to the due south-zenith-due north direction, the airspace boundary line is delineated and confirmed, expressed as:

[0121]

[0122] and (x) c y c Convert Cartesian coordinates to polar coordinates.

[0123] (9) Clarify the frequency allocation rules for airspace cells {f1,f2,...f j The assignment formula is as follows:

[0124] f cell =f(c mod j)+1

[0125] c represents the airspace cell row number, f cell This refers to the frequency group assigned to the airspace cell.

[0126] Steps (7) to (9) above are the steps for setting spatial partitioning parameters.

[0127] (10) Form a joint air-ground frequency allocation scheme {f1,f2,...,fj,...f i×j The assignment formula is as follows:

[0128] f i×j = f{[(a+b)mod i]×j+c+1}

[0129] f represents the frequency group ultimately assigned to the visible airspace cells of a specific ground cell user.

[0130] Among them, step (6) ground partition F cell This refers to the ground first dividing the total frequency band, such as... Figure 6 As shown in the upper part, the reuse factor i = 3, dividing the total frequency band into three segments: F1, F2, and F3. Step (9) Spatial cell f cell This involves further refining the already allocated frequency bands, such as... Figure 6 The lower half shows that the first ground division F1 is further divided into space divisions f1, f2, and f3; the second ground division F2 is further divided into space divisions f4, f5, and f6, and so on. When there are multiple visible satellites in the same airspace cell, frequency assignment will be prioritized for the satellite with the highest elevation angle.

[0131] (11) Determine whether the I / N ratio has reached the expected target. Compare the CCDF (Complementary Cumulative Distribution Function) curve of I / N with the I / N limit. If it is greater than the limit, the expected target has not been reached; if it is less than the limit, the expected target has been reached.

[0132] If the condition is not met, proceed to step (4); if the condition is met, proceed to step (12).

[0133] (12) Complete the optimization and determine the partitioning strategy.

[0134] In a specific implementation, an interference mitigation method based on tracking region coding for spatial frequency planning is used for two constellations, Constellation A (small constellation) and Constellation B (large constellation). The orbital parameters of the two constellations are shown in Table 1.

[0135] Table 1 Orbital parameters of non-geostationary communication constellations

[0136] Zodiac Sign A Zodiac Sign B track inclination 88° 88° Total number of track planes / 4 4 Number of satellites per orbit / satellites 15 35 Orbital altitude / km 1700 1500

[0137] Specific Implementation Example 1: The following is an example of a frequency interference mitigation scheme designed using a spatial frequency planning method based on tracking region coding for a small constellation A.

[0138] Constellation A is a near-polar orbit constellation that can provide global communication services. It is assumed that the hotspot area is the region with longitude from 0° to 5° east and latitude from 30° to 35° north.

[0139] The first step is to obtain the I / N distribution of satellite-to-ground link interference noise ratio for users in high-demand areas, such as... Figure 4 As shown.

[0140] The second step is to set the user satellite-to-ground link I / N optimization target, establishing a goal for the subsequent optimization process. The optimization target is that the I / N ratio at each time percentage is less than -12.2dB, which is the limit of -12.2dB in the figure.

[0141] The third step is to perform regional regularization on the hotspot areas, which involves dividing the geographical region into a regular grid. Here, we assume the hotspot area is located between 0°E and 5°E longitude and between 30°N and 35°N latitude. This region is initialized and divided randomly, starting with a smaller value; here, a quadrilateral with 5 rows and 5 columns is randomly selected.

[0142] The fourth step is to encode the regularized n-row m-column polygonal region by using each cell to be uniquely identified by row number a (0 to n-1) and column number b (0 to m-1), forming a unique ground cell code identifier (a, b) for the hotspot area.

[0143] Fifth step, set the ground cell frequency reuse factor i. The initial value of i is randomly selected, starting from a small value. Here, it is randomly selected as 3.

[0144] Step 6: Assign ground cell frequency groups {F1, F2, F3}. Based on the ground cell codes and frequency reuse factors, assign the frequency groups to various ground cells using the following formula:

[0145] F cell =F{((a+b)mod i)+1}

[0146] a and b are the row and column numbers respectively, F cell This refers to the frequency groups assigned to terrestrial cells. Frequency groups for assigning terrestrial cells in hotspot areas are as follows: Figure 5 As shown, the starting row and column numbers begin from the bottom left corner.

[0147] For example: the bottom left corner is the starting cell, cell (0, 0) corresponds to a being 0 and b being 0, according to F cell =F{((a+b)mod i)+1}=F{((0+0)mod 3)+1}=F1

[0148] Steps four through six above are the steps for setting ground zoning parameters.

[0149] Step 7: Set the number of cells j within the visible airspace of the ground station to 3, and the initial value of the airspace frequency band overlap percentage to 33%. Figure 6 As shown.

[0150] The initial value of j is randomly selected, starting with a small value; here, it's randomly chosen as 3. This is equivalent to dividing the airspace into several groups within a fixed ground cell, and allocating frequencies to the corresponding groups. The initial percentage is also randomly determined; if the percentage is 33%, then adjacent airspace frequency allocations can overlap by 33%.

[0151] Step 8: Divide the airspace into cells along a uniform arc from due south to due north. First, divide the airspace into cells along a uniform arc from due south to zenith to due north to determine the boundary points of the airspace cells.

[0152] The airspace boundary point y of the c-th (0 to j-1) cell c The calculation formula is:

[0153] y c =-90+c×180÷j

[0154] Secondly, using the airspace boundary point as the endpoint, and perpendicular to the due south-zenith-due north direction, the airspace boundary line is delineated and confirmed, expressed as:

[0155]

[0156] and (x) c y c Convert Cartesian coordinates to polar coordinates.

[0157] The spatial domain is divided using a polar coordinate system, which facilitates the division of spatial regions using azimuth and elevation angles. Therefore, it is necessary to divide (x...) into polar coordinates. c y c Convert Cartesian coordinates to polar coordinates.

[0158] Step 9: Define the airspace cell frequency assignment rules {f1, f2, f3}. The assignment formula is as follows:

[0159] f cell =f(c mod j)+1

[0160] c represents the airspace cell row number, f cell This refers to the frequency group assigned to the airspace cell.

[0161] c takes values ​​from 0 to j-1. When j is 3, f cell They are f1, f2, and f3, respectively.

[0162] Steps (7) to (9) above are the steps for setting spatial partitioning parameters.

[0163] Step 10: Formulate a joint air-to-ground frequency assignment scheme {f1, f2, ... f9}. The assignment formula is as follows:

[0164] f i×j = f{[(a+b)mod 3]×3+c+1}

[0165] f represents the frequency group ultimately assigned to a specific ground cell user's visible airspace cell. When there are multiple visible satellites in the same airspace cell, frequency allocation will prioritize the satellite with the highest elevation angle.

[0166] like Figures 7 to 21 As shown, this is the final frequency assignment state of constellation A in specific embodiment one.

[0167] Step 11: Determine whether the I / N ratio has achieved the expected optimization goal. For example... Figure 22 As shown, the results have met the requirement that I / N is less than the -12.2dB limit under each time percentage condition, so proceed to step twelf.

[0168] Step 12: Complete the optimization and determine the partitioning strategy.

[0169] Specific Implementation Example 2: Constellation B is a near-polar orbit constellation that can provide global communication coverage. It is assumed that the hotspot area is located between 0°E and 5°E longitude and between 30°N and 35°N latitude. The following design uses an interference mitigation scheme based on a spatial frequency planning method using tracking area coding.

[0170] The first step is to obtain the I / N distribution of satellite-to-ground link interference noise ratio for users in high-demand areas. For example... Figure 23 As shown.

[0171] The second step is to set the user satellite-to-ground link I / N optimization target, establishing a goal for the subsequent optimization process. The target is that the I / N ratio at each time percentage is less than -12.2dB, which is the limit of -12.2dB in the figure.

[0172] The third step is to perform regional regularization on the hotspot areas, which involves dividing the geographical region into a regular grid. Here, we assume the hotspot area is located between 0°E and 5°E longitude and between 30°N and 35°N latitude. This area is divided into 5 rows and 5 columns of hexagons.

[0173] The fourth step is to encode the regularized n-row m-column polygonal region by using each cell to be uniquely identified by row number a (0 to n-1) and column number b (0 to m-1), forming a unique ground cell code identifier (a, b) for the hotspot area.

[0174] Fifth step, set the ground cell frequency reuse factor to 3.

[0175] Step 6: Assign terrestrial cell frequency groups {F1, F2, ..., F i Based on the terrestrial cell code and frequency reuse factor, frequency groups are assigned to various terrestrial cells. The assignment formula is as follows:

[0176] F cell =F((a+b)mod i)+1

[0177] a and b are the row and column numbers respectively, F cell This refers to the frequency group assigned to the ground cell.

[0178] Steps four through six above are the steps for setting ground zoning parameters. For example... Figure 24 As shown.

[0179] Step 7: Set the number of cells j within the visible airspace of the ground station to 5. The initial value for the percentage of overlapping frequencies in the airspace frequency bands is 45%. (For example...) Figure 25 As shown.

[0180] Step 8: Divide the airspace into cells along a uniform arc from due south to due north. First, divide the airspace along a uniform arc from due south to zenith to due north to determine the cell boundary points. The airspace boundary point y of the c-th cell...c The calculation formula is:

[0181] y c =-90+c×180÷j

[0182] Secondly, using the airspace boundary point as the endpoint, and perpendicular to the due south-zenith-due north direction, the airspace boundary line is delineated and confirmed, expressed as:

[0183]

[0184] and (x) c y c Convert Cartesian coordinates to polar coordinates.

[0185] Step 9: Define the airspace cell frequency allocation rules {f1, f2, ... f j The assignment formula is as follows:

[0186] f cell =f(c mod j)+1

[0187] c represents the airspace cell row number, f cell This refers to the frequency group assigned to the airspace cell.

[0188] Steps seven through nine above are the steps for setting spatial partitioning parameters.

[0189] Step 10: Formulate a joint air-to-ground frequency allocation scheme {f1, f2, ... f j ..f i×j The assignment formula is as follows:

[0190] f i×j = f{[(a+b)mod i]×j+c+1}

[0191] f represents the frequency group ultimately assigned to a specific ground cell user's visible airspace cell. When there are multiple visible satellites in the same airspace cell, frequency allocation will prioritize the satellite with the highest elevation angle.

[0192] like Figures 26-41 As shown, this is the final frequency assignment state of constellation B in specific embodiment two.

[0193] Step 11: Determine whether the I / N ratio has achieved the expected optimization goal. For example... Figure 43 As shown, after the first optimization, the I / N ratio is still greater than the -12.2dB limit at a certain percentage of time, which does not meet the expected optimization goal, so we return to the fourth step.

[0194] like Figure 42As shown, the optimization strategy parameters are readjusted to reduce the percentage of overlapping frequencies in the airspace from 45% to 10%, thereby reducing the power of co-channel interference. Other parameters remain unchanged in steps four through ten.

[0195] The I / N ratio has reached the expected optimization target, and the results show that the I / N ratio is less than the -12.2dB limit under each time percentage condition. Proceed to step twelfth.

[0196] Step 12: Complete the optimization and determine the partitioning strategy.

[0197] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. An interference mitigation method based on tracking region coding for spatial frequency planning, characterized in that, The steps are as follows: (1) Obtain the CCDF curves of the interference-to-noise ratio (I / N) distribution of satellite-to-ground links for users in demand hotspot areas; (2) Set user satellite-to-ground link I / N limits; (3) Implement regional regularization for hot demand areas, including ground regularization zoning of hot demand areas and visible airspace zoning of satellite ground stations; (4) Set the ground regularization partitioning parameters for hotspot areas; (5) Set the visible airspace partitioning parameters for the satellite ground station; (6) Based on the parameters set in steps (4) and (5), a joint air-ground frequency assignment scheme is formed; (7) Determine whether the interference-to-noise ratio I / N has reached the expected optimization target based on the criterion conditions; if it is satisfied, then complete the optimization and determine the partitioning strategy; if it is not satisfied, repeat steps (4) to (6) until the optimization target is met.

2. The interference mitigation method for spatial frequency planning based on tracking region coding according to claim 1, characterized in that, The ground regularization partitioning of the hotspot area mentioned in step (3) includes quadrilateral grid partitioning and hexagonal grid partitioning.

3. An interference mitigation method for spatial frequency planning based on tracking region coding according to claim 1 or 2, characterized in that, The steps for setting the parameters for ground regularization partitioning of hotspot areas are as follows: 1) Divide the ground of a hotspot area into a grid of n rows and m columns; 2) For the regularized n-row m-column ground cell coding, each cell is uniquely identified by the row number a and the column number b; where a takes values ​​from 0 to n-1, and b takes values ​​from 0 to m-1; 3) Set the frequency reuse factor i for the ground cell; 4) Assigning terrestrial cell frequency group F cell ={F1,F2,...,F i The assignment formula is as follows: F i =F{[(a+b)mod i]+1} a is the row number of the ground cell, b is the column number of the ground cell, F i This refers to the frequency allocated to the ground cells.

4. The interference mitigation method for spatial frequency planning based on tracking region coding according to claim 3, characterized in that, The initial values ​​of the n rows and m columns, and the initial value of the frequency reuse factor i, are all randomly selected.

5. The interference mitigation method for spatial frequency planning based on tracking region coding according to claim 1, characterized in that, The regularized partitioning of the visible airspace of the satellite ground station described in step (3) is a strip-shaped arrangement with equal arcs along the direction of due south-zenith-due north.

6. An interference mitigation method for spatial frequency planning based on tracking region coding according to claim 1 or 5, characterized in that, The regularization partitioning parameters for setting the visible spatial domain of the satellite ground station include: Set the number of cells j in the visible airspace of the ground station, and set the percentage of overlapping frequencies in the airspace frequency bands; Divide the airspace visible to the ground station into cells c along an equal arc from due south to zenith to due north, and determine the cell boundary points of the airspace; The airspace boundary point y of the c-th cell c The calculation formula is: and c =-90+c×180÷j Using the airspace boundary point as the endpoint, and perpendicular to the due south-zenith-due north direction, the airspace boundary line is delineated and confirmed, expressed as: and (x) c y c Convert Cartesian coordinates to polar coordinates; Assigning airspace cell frequency group F cell ={f1,f2,...f j The assignment formula is as follows: f j =f[(c mod j)+1] c takes values ​​from 0 to j-1; f j This refers to the frequency assigned to the airspace cell.

7. The interference mitigation method for spatial frequency planning based on tracking region coding according to claim 6, characterized in that, The spatial cell frequency group {f1,f2,...f j } refers to the frequency group of the ground cell {F1,F2,...,F} i Further division of each frequency band in}, where i is the frequency reuse factor of the ground cell.

8. The interference mitigation method for spatial frequency planning based on tracking region coding according to claim 6, characterized in that, The initial values ​​for the number of cells j in the visible airspace of the ground station and the percentage of overlapping frequencies in the airspace frequency bands are randomly selected.

9. The interference mitigation method for spatial frequency planning based on tracking region coding according to claim 1, characterized in that, Step (6) involves joint air-ground frequency assignment f = {f1, f2, ..., f} j ,...f i×j The formula is as follows: f i×j =f{[(a+b)mod i]×j+c+1} f i×j The frequency of the visible airspace cells is ultimately assigned to specific ground cell users; a is the row number of the ground cell, b is the column number of the ground cell, c is the row number of the airspace cell, and j is the number of cells in the visible airspace of the ground station.

10. The interference mitigation method for spatial frequency planning based on tracking region coding according to claim 1, characterized in that, The criteria for step (7) are as follows: if the CCDF curve of the user's satellite-to-ground link interference noise ratio (I / N) is greater than the I / N limit, then the expected target has not been achieved; if the CCDF curve of the user's satellite-to-ground link interference noise ratio (I / N) is smaller than the I / N limit, then the expected target has been achieved.

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