A worst-case interference analysis method based on time extrapolation

Abstract

The present invention discloses a worst-case interference analysis method based on time extrapolation, the method comprising: defining the satellite visible coverage area by the elevation angle limit of the ground reference point, thereby establishing an optimal judgment mechanism for the worst-case interference scenario, and designing a calculation model for the worst-case interference scenario; according to the judgment mechanism and the calculation model, in combination with characteristic parameters including beam width and orbital altitude, designing a simulation parameter calculation method based on time extrapolation. Aiming at the demand for effective and reliable interference simulation of low-orbit communication constellations, the present invention analyzes the aggregate interference model under the dynamic scenario based on time extrapolation, studies the optimal judgment mechanism for the worst-case interference scenario, achieves the analysis goal of maximizing interference, breaks through the core model problem that restricts the frequency-orbit resource compatibility assessment of space giant constellation systems, and provides technical support for constellation system frequency compatibility analysis.

Description

Technical Field

[0001] The present invention belongs to the technical field of constellation interference analysis, and in particular relates to a worst-case scenario interference analysis method based on time extrapolation. Background Art

[0002] The frequency compatibility interference analysis modeling for NGSO (Non-Geo-Stationary Orbit) constellation systems is significantly different from that for GSO (Geo-Stationary Orbit) satellite systems. This is primarily due to the following: (1) NGSO constellations have a large number of satellites. When NGSO satellites and their constellations pass through the path between GSO earth stations and satellites, the risk of NGSO-GSO satellite interference increases significantly. (2) Because NGSO satellites are in high-speed motion, earth station antennas are constantly switching beams and satellites. The interference between NGSO and GSO systems changes dynamically over time and space, significantly increasing the complexity of interference analysis. Currently, the theoretical foundation for compatibility analysis of giant low-orbit constellations is relatively weak, and a globally standardized compatibility analysis and evaluation method has yet to be established. Based on the principle of maximizing interference analysis, how to obtain reliable and effective interference analysis results has become a hot topic. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects of the prior art and propose a worst-case interference analysis method based on time extrapolation.

[0004] To achieve the above objectives, the present invention proposes a worst-case interference analysis method based on time extrapolation, the method comprising:

[0005] The satellite visible coverage area is defined by the elevation angle limit of the ground reference point, thereby establishing the optimal judgment mechanism for the worst interference scenario and designing a calculation model for the worst interference scenario;

[0006] According to the judgment mechanism and calculation model, combined with characteristic parameters including beam width and orbit height, a simulation parameter calculation method based on time extrapolation is designed.

[0007] As an improvement to the above method, the worst interference scenarios include: interference scenarios between a low-orbit communication constellation system and a high-orbit satellite, and between low-orbit communication constellation systems.

[0008] As an improvement to the above method, for the worst interference scenario, the satellites of the interfered system are analyzed, and the objective function for calculating the worst interference scenario is defined as:

[0009]

[0010] The corresponding constraints are:

[0011]

[0012] in, is the interference-to-noise ratio of the communication link between the satellite and the ground station of the disturbed system, with a total of N t NGSO satellites, M t ground test points; i, j represent the i-th NGSO satellite and the j-th test point respectively; M(lon,lat,h) is the test point, that is, the location where the satellite system ground station appears, lon,lat,h are the longitude, latitude and altitude coordinates of the test point respectively, θ (th) is the ground station elevation angle limit, θ is the ground station elevation angle, higher than θ (th) Have the conditions for chain building.

[0013] As an improvement to the above method, the solution is The maximum value problem, traversing N t NGSO satellites, and get the angular velocity ω corresponding to the i-th NGSO satellite sati , thus obtaining the distribution of the locations of ground stations within the visible range of the interfering and interfered system satellites.

[0014] As an improvement of the above method, the designed simulation parameters include: the downlink time step Δt corresponding to different interfering NGSO satellites by traversing the earth station stepi-down , select the minimum value and determine the downlink interference simulation time step Δt that is suitable for the constellation system s-down :

[0015] Δt s-down =min(Δt stepi-down )

[0016]

[0017] Where Δt idown N is the time required for the i-th interfering NGSO satellite to pass through the main lobe radiation area of ​​the receiving antenna of the victim system earth station in the downlink. step-down is the number of sampling times of the main lobe radiation area of ​​the receiving antenna of the victim system earth station, satisfying the following formula:

[0018]

[0019] Where, ΔR down is the resolution of the interference signal power I received by the earth station, Indicates rounding up.

[0020] As an improvement of the above method, the designed simulation parameters include: the uplink time step Δt corresponding to different interfering NGSO satellites by traversing the earth station stepi-up , select the minimum value to determine the uplink interference simulation time step Δt that is suitable for the constellation system s-up :

[0021] Δt s-up =min(Δt stepi-up )

[0022]

[0023] Where Δt iup N is the time required for the main lobe area of ​​the receiving antenna beam of the i-th interfered NGSO satellite in the uplink to pass through the interfering earth station, step-up is the number of sampling times in the main lobe radiation area of ​​the NGSO satellite receiving antenna of the victim system, satisfying the following formula:

[0024]

[0025] Wherein, ΔR is the resolution of the interference signal power I received by the NGSO satellite of the interfered system.

[0026] As an improvement to the above method, the designed simulation parameters also include: the total simulation time T between constellation systems is obtained according to the following formula: total for:

[0027]

[0028] T orbits =max(T sat ,T sati )

[0029] in, represents the geocentric angle that the i-th interfering NGSO satellite passes through when passing the earth station, corresponding to the minimum time step. N step The number of sampling times of the main lobe radiation area of ​​the receiving antenna of the disturbed earth station corresponding to the minimum time step adopted, N step ∈{N step-up ,N step-down}, T orbits is the longest orbital period adopted, T sat is the orbital period of the disturbed NGSO constellation satellite; T sati is the orbital period of the i-th interfering NGSO constellation satellite;

[0030] The total number of time steps N is obtained according to the following formula total for:

[0031]

[0032] in, Indicates rounding down, Δt s ∈{Δt s-down ,Δt s-up}

[0033] Compared with the prior art, the advantages of the present invention are:

[0034] Aiming at the demand for effective and reliable interference simulation of low-orbit communication constellations, this invention analyzes the aggregate interference model under the time-extrapolated dynamic scenario and studies the optimal judgment mechanism for the worst interference scenario, achieving the analysis goal of maximizing interference. This overcomes the core model issues that restrict the frequency-orbit resource compatibility assessment of space giant constellation systems, and provides technical support for the frequency compatibility analysis of constellation systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is the organizational structure of the worst-case scenario interference analysis method based on time extrapolation;

[0036] Figure 2(a) shows the NGSO satellite antenna reference plane (A, B) coordinate system;

[0037] Figure 2(b) shows the NGSO satellite antenna observation coordinate system;

[0038] Figure 3(a) shows the traversal angle of the NGSO satellite to the test point M;

[0039] Figure 3(b) shows the maximum traversal range of the NGSO satellite;

[0040] Figure 4 is the directivity pattern of the receiving antenna of the earth station of the interfered NGSO constellation system;

[0041] Figure 5(a) shows the situation of the interfering NGSO satellite passing through the main lobe of the receiving antenna of the interfered system in the downlink;

[0042] Figure 5(b) shows the situation of the interfering NGSO satellite passing through the main lobe of the receiving antenna of the interfered system in the uplink. DETAILED DESCRIPTION

[0043] In view of the above needs, the present invention intends to carry out research on the worst interference scenario evaluation simulation model based on time extrapolation. First, according to the aggregate interference analysis scenarios between low-orbit giant communication constellation systems and high-orbit satellites, and between low-orbit giant communication constellation systems, based on time slicing, combined with the application scenarios of fixed beams and phased array adjustable beams, the method of grid traversal within the coverage range of satellite beams is used to design the mechanism and model for optimal judgment of the worst interference scenario; secondly, the simulation parameters based on time extrapolation are studied, and the correlation between the characteristic parameters such as satellite orbits and beams and the simulation step size and duration are derived and analyzed. The organizational structure of the research content is as follows: Figure 1 shown.

[0044] Key technologies:

[0045] Key Technology 1: Optimal Judgment Mechanism and Model Design for the Worst Interference Scenario

[0046] This technology proposes an optimal determination mechanism for worst-case interference scenarios, providing a reference for frequency compatibility analysis of giant LEO constellations. This key technology analyzes interference analysis scenarios between typical LEO communication constellations and high-Earth orbit satellites, as well as between LEO communication constellations. It considers both fixed-beam and phased-array agile beam configurations, defines satellite visible coverage areas through elevation angle limits at ground reference points, studies the optimal determination mechanism for worst-case interference scenarios, and designs a calculation model for worst-case interference scenarios.

[0047] Key Technology 2: Simulation Parameter Design Based on Time Extrapolation

[0048] This technology designs a simulation parameter calculation method based on time extrapolation based on the optimal judgment mechanism and calculation model for the worst interference scenario proposed in Key Technology 1, combined with characteristic parameters such as beam width and orbit altitude.

[0049] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0050] Example

[0051] The embodiment of the present invention proposes a worst-case scenario interference analysis method based on time extrapolation.

[0052] The technical route of the present invention is: first, analyze the interference analysis scenarios between typical low-orbit communication constellation systems and high-orbit satellites, and between low-orbit communication constellation systems, define the satellite visible coverage area through the ground reference point elevation angle limit, and use the grid traversal method within the satellite beam coverage range to study the optimal judgment mechanism of the worst interference scenario and design the worst interference scenario calculation model. Then, according to the ground station location information of the worst interference scenario, and combined with characteristic parameters such as beam width and orbit altitude, design a simulation parameter calculation method based on time extrapolation.

[0053] 1) Optimal judgment mechanism and interference analysis calculation method for the worst interference scenario

[0054] The angle θ is defined as the angle between the line from the center of the Earth to the surface test point M and the line from the center of the Earth to the NGSO satellite. is the angle between the line connecting the NGSO satellite to its sub-satellite point S and the line connecting the NGSO satellite to the surface test point M. Using the polar coordinate transformation principle, let The NGSO satellite antenna reference plane (A, B) coordinate system is established. At the same time, the NGSO satellite earth observation coordinate system is constructed from the NGSO satellite observation perspective, as shown in Figure 2, where Figure 2(a) is the NGSO satellite antenna reference plane (A, B) coordinate system, and Figure 2(b) is the NGSO satellite antenna observation coordinate system.

[0055] In the NGSO satellite antenna reference plane (A, B) coordinate system, the polar coordinates of the test point M and the antenna beam center point C in the (A, B) coordinate system are and In the NGSO satellite observation coordinate system, the NGSO satellite Earth observation angle σ e,s , σ a,s and θ in the (A,B) coordinate system The geometric relationship is

[0056]

[0057] Figure 3(a) shows the maximum traversal angle of the NGSO satellite to the test point M. Figure 3(b) shows the maximum traversal range of the NGSO satellite. Mesh traversal range and maximum traversal angle

[0058] Therefore, in interference analysis, it is necessary to traverse the interference system or the disturbed system observation field (σ e,s ,σ a,s ) the positions of all surface test points M within As shown in the black dots in Figure 3(b).

[0059] The maximum traversal angle of the i-th NGSO satellite can be derived from the working elevation angle at the test point M: The value of

[0060]

[0061] Where R e is the radius of the Earth, m; ε i is the current operating elevation angle of the surface test point M to the i-th NGSO satellite, rad; R ngsois the distance from the i-th NGSO satellite to the center of the earth, m. In addition, when traversing, if there are multiple {M i} Calculated by test point If the NGSO satellite passes by the test point with the lowest angular velocity, the NGSO satellite will observe the test point (σ e,s ,σ a,s ) the positions of all surface test points M within The following constraints need to be considered when traversing the grid, namely

[0062]

[0063] Where, lat M For test points Latitude location; σ a,M For test points The observation azimuth of the i-th NGSO satellite; α is the test point The spatial isolation angle for the i-th NGSO satellite; α th For test points The threshold of the spatial isolation angle is a value that is related to lat M Related functions; ε min is the minimum operating elevation angle of the surface test point M.

[0064] For the worst interference between low-orbit communication constellation systems or between them and high-orbit satellites, consider the single-satellite analysis scenario of the interfered system. The objective function is defined as follows

[0065]

[0066] The corresponding constraints are

[0067]

[0068] Among them, point M is the test point described above, that is, the location where the satellite system ground station appears, defined by the location coordinates longitude and latitude, θ is the elevation angle of the ground station, θ (th) is the elevation angle limit of the ground station. If the value is higher than the threshold, the link establishment condition is met. The worst interference analysis scenario model can be converted into a solution calculation to obtain The maximum value problem of is solved, and then the distribution of the ground stations within the visible range of the interfering and disturbed system satellites is obtained, so as to achieve the purpose of worst-case scenario analysis.

[0069] 2) Simulation parameter design method based on time extrapolation

[0070] In the Earth Centered Inertial (ECI) coordinate system, the disturbed and interfering NGSO constellation systems can be considered as a distribution family of satellites and earth stations in the system. This family is a set of independent and identically distributed random variables. The simulation time step should take into account the situation where the shortest time interference between systems exceeds a certain limit while ensuring the accuracy of the calculation results. According to the spatial orbit characteristics of the NGSO constellation system, the time step Δt suitable for the interference simulation between constellation systems is determined. s Should be the time step Δt in all individual subsystems stepi The minimum value of

[0071] Δt s =min(Δt stepi ) (6)

[0072] Determine the appropriate time step parameter Δt for constellation system interference simulation step The basis is to ensure that Δt step The selection of just covers the worst interference situation in the shortest time from the interfering NGSO constellation system. For the downlink, this worst interference is caused by the satellite of the interfering NGSO constellation system passing through the main lobe of the receiving antenna of the earth station of the interfered NGSO constellation system. The specific time step of the downlink is

[0073]

[0074] Where Δt step-down is the time step of the downlink; Δt down N is the time required for the interfering NGSO satellite to pass through the main lobe radiation area of ​​the receiving antenna of the earth station of the interfered system in the downlink, which is related to the orbit characteristics of the interfering NGSO satellite and the relative position of the interfered NGSO satellite and the earth station; step-down is the number of sampling times of the main lobe radiation area of ​​the receiving antenna of the victim system earth station, which is related to the resolution dI of the calculated interference signal power I, the 3dB beamwidth and radiation pattern of the receiving antenna of the victim earth station.

[0075] Similarly, the time step of the uplink is

[0076]

[0077] Where Δt upi N is the time required for the main lobe area of ​​the uplink interfered NGSO satellite receiving antenna beam to pass through the interfering earth station, step-up is the sampling number of the main lobe radiation area of ​​the NGSO satellite receiving antenna of the interfered system.

[0078] Figure 4is the directional pattern of the receiving antenna of the earth station of the disturbed NGSO constellation system. It can be seen that the number of sampling times N of the main lobe radiation area of ​​the receiving antenna of the earth station of the disturbed system step-down With 3dB beamwidth θ 3dB The specific relationship is

[0079]

[0080] where Δθ is the sampling interval of the main lobe off-axis angle θ of the receiving antenna of the disturbed NGSO system earth station.

[0081] Considering that the off-axis angle of the earth station receiving antenna is in the main lobe area, that is, |θ|≤θ 3dB / 2, according to the reference of the earth station receiving antenna given in ITU rules and recommendations, the interference NGSO system earth station receiving antenna and θ / θ can be obtained 3dB relationship.

[0082] The main lobe gain of the earth station receiving antenna g(θ) = g max -12(θ / θ 3dB ) 2 Take this as an example for analysis,

[0083]

[0084] Substituting equation (14) into equation (15), the antenna main lobe gain increment dg(θ) can be expressed as

[0085]

[0086] Considering the symmetry of the antenna pattern on both sides of the main lobe, if we want to fully retain the information on both sides of the antenna main lobe, we need to meet the following constraints:

[0087]

[0088] The resolution dI of the interference signal power I received by the NGSO victim earth station is denoted as ΔR.

[0089] From equations (7), (11) and (12), we can get the sampling number N of the main lobe radiation area of ​​the receiving antenna of the victim system earth station: step-down The specific form of the restriction is

[0090]

[0091] Figure 5(a) shows the situation where the downlink interfering NGSO satellite passes through the main lobe radiation area of ​​the receiving antenna of the earth station of the interfered system S. The time Δt when the interfering NGSO constellation system S' satellite passes is downi for

[0092]

[0093] Where, is the geocentric angle that the downlink interfering NGSO satellite passes through in the main lobe radiation area of ​​the receiving antenna of the victim system, rad; ω sati is the angular velocity of the interfering NGSO satellite during its passage, rad / s.

[0094] Similarly, as shown in Figure 5(b), when the main lobe area of ​​the uplink interfered NGSO satellite receiving antenna beam passes through the interfering earth station, the time Δt upi for

[0095]

[0096] Where, is the geocentric angle that the main lobe area of ​​the uplink interfered NGSO satellite receiving antenna beam passes through when passing through the interfering earth station, rad; ω sati is the angular velocity of the disturbed NGSO satellite during its transit, rad / s.

[0097] From equations (6)-(9), (14), (15) and The total simulation time T between constellation systems can be obtained total and the total number of steps N total :

[0098]

[0099] in, The geocentric angle that the NGSO satellite corresponding to the subsystem of the minimum time step adopted passes through when passing the earth station, N step The number of sampling times of the main lobe radiation area of ​​the receiving antenna of the disturbed earth station corresponding to the subsystem of the minimum time step adopted, N step ∈{N step-up ,N step-down}, T orbits T orbits =max(T sat ,T sati ), where T sat is the orbital period of the disturbed NGSO constellation satellite; T sati is the orbital period of the interfering NGSO constellation system satellite. The total number of time steps N total for

[0100]

[0101] in, Indicates rounding down, Δt s ∈{Δt s-d own ,Δt s-up}.

[0102] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and are intended to be encompassed by the claims of the present invention.

Claims

1. A worst-case interference analysis method based on time extrapolation, the method comprising: The satellite visible coverage area is defined by the elevation angle limit of the ground reference point, thereby establishing the optimal judgment mechanism for the worst interference scenario and designing a calculation model for the worst interference scenario; Based on the judgment mechanism and calculation model, combined with characteristic parameters including beam width and orbit height, a simulation parameter calculation method based on time extrapolation is designed; The worst interference scenarios include: interference scenarios between low-orbit communication constellation systems and high-orbit satellites, and between low-orbit communication constellation systems; For the worst interference scenario, the satellites of the interfered system are analyzed, and the objective function for calculating the worst interference scenario is defined as: The corresponding constraints are: in, is the interference-to-noise ratio of the communication link between the satellite and the ground station of the disturbed system, with a total of N t NGSO satellites, M t ground test points; i, j represent the i-th NGSO satellite and the j-th test point respectively; M(lon,lat,h) is the test point, that is, the location where the satellite system ground station appears, lon,lat,h are the longitude, latitude and altitude coordinates of the test point respectively, θ (th) is the ground station elevation angle limit, θ is the ground station elevation angle, higher than θ (th) Have the conditions for chain building.

2. The worst-case interference analysis method based on time extrapolation according to claim 1, characterized in that: Solve calculation The maximum value problem, traversing N t NGSO satellites, and get the angular velocity ω corresponding to the i-th NGSO satellite sati , thus obtaining the distribution of the locations of ground stations within the visible range of the interfering and interfered system satellites.

3. The worst-case scenario interference analysis method based on time extrapolation according to claim 1, characterized in that: The designed simulation parameters include: downlink time step Δt corresponding to different interfering NGSO satellites by traversing the earth station stepi-down , select the minimum value and determine the downlink interference simulation time step Δt that is suitable for the constellation system s-down : Δt s-down =min(Δt stepi-down ) Where, Δt idown N is the time required for the i-th interfering NGSO satellite to pass through the main lobe radiation area of ​​the receiving antenna of the victim system earth station in the downlink. step-down is the number of sampling times of the main lobe radiation area of ​​the receiving antenna of the victim system earth station, satisfying the following formula: Where, ΔR down is the resolution of the interference signal power I received by the earth station, Indicates rounding up.

4. The worst-case scenario interference analysis method based on time extrapolation according to claim 3, characterized in that: The designed simulation parameters include: the uplink time step Δt corresponding to different interfering NGSO satellites by traversing the earth station stepi-up , select the minimum value to determine the uplink interference simulation time step Δt that is suitable for the constellation system s-up : Δt s-up =min(Δt stepi-up ) Where, Δt iup N is the time required for the main lobe area of ​​the receiving antenna beam of the i-th interfered NGSO satellite in the uplink to pass through the interfering earth station, step-up is the number of sampling times in the main lobe radiation area of ​​the NGSO satellite receiving antenna of the victim system, satisfying the following formula: Wherein, ΔR is the resolution of the interference signal power I received by the NGSO satellite of the interfered system.

5. The worst-case scenario interference analysis method based on time extrapolation according to claim 4, characterized in that: The designed simulation parameters also include: the total simulation time T between constellation systems is obtained according to the following formula: total for: T orbits =max(T sat ,T sati ) in, represents the geocentric angle that the i-th interfering NGSO satellite passes through when passing the earth station, corresponding to the minimum time step. N step The number of sampling times of the main lobe radiation area of ​​the receiving antenna of the disturbed earth station corresponding to the minimum time step adopted, N step ∈{N step-up ,N step-down }, T orbits is the longest orbital period adopted, T sat is the orbital period of the disturbed NGSO constellation satellite; T sati is the orbital period of the i-th interfering NGSO constellation satellite; The total number of time steps N is obtained according to the following formula total for: in, Indicates rounding down, Δt s ∈{Δt s-down ,Δt s-up }.

Images