High and low orbit inter-satellite and satellite-ground co-frequency communication interference suppression method based on evasion angle

Abstract

The invention relates to a high and low orbit inter-satellite and satellite-ground co-frequency communication interference suppression method based on an evasion angle, and belongs to the technical field of satellite communication. The method comprises the following steps: 1) determining an NGSO satellite orbit height h communicating with a GSO satellite, and calculating a maximum directable angle; 2) calculating a semi-apex angle gamma from the NGSO satellite to the ground; 3) traversing arrival angles of ground test points and calculating related parameters; 4) calculating the PFD of the NGSO satellite, comparing the PFD with a ground PFD limit value, and if the PFD does not meet the ground PFD limit value, performing power adjustment to enable the PFD to meet the ground PFD limit value; and 5) adopting inter-satellite communication of an evasion angle. By establishing an integrated same-frequency interference suppression mechanism such as orbit height judgment, maximum directable angle calculation, power flux density dynamic control and evasion angle link selection, compatible coexistence of satellite-ground and inter-satellite communication of high and low orbit satellites in the same frequency band is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of satellite communication, and relates to a high-low orbit intersatellite and satellite-earth same-frequency communication interference suppression method based on avoidance angle. BACKGROUND

[0002] In the field of satellite communication, with the rapid development of satellite NGSO (Non-Geostationary Satellite Orbit) constellation, it has become an inevitable trend that GSO satellites (Geostationary Satellite Orbit) and NGSO satellites share the same frequency band in intersatellite and satellite-earth communication, leading to increasingly prominent same-frequency interference problems. The existing technology mainly realizes interference suppression through power control, beam forming and other methods. For example, dynamic power adjustment is used to reduce the downlink interference of NGSO satellites on GSO systems, or beam forming technology is used to avoid interference direction. These methods ensure spectrum compatibility to a certain extent, but often rely on static thresholds or preset models, and cannot fully adapt to the rapid motion of NGSO satellites and the dynamic changes of orbits, resulting in low interference suppression efficiency, frequent communication interruption or insufficient resource utilization. Specifically, although the existing power control scheme can reduce the leakage signal, it ignores the real-time optimization of the geometric pointing angle, which is easy to cause the power flux density (PFD) to exceed the limit or the intersatellite link to be interrupted; although the beam forming method can directional transmission, it has high computational complexity and is not suitable for real-time application of large-scale constellation.

[0003] In the prior art, for example, in patent US20120238203A1 "A non-interfering utilization of non-geostationary satellite systems", it is proposed to separate the GSO frequency band from the NGSO frequency band to avoid interference. However, this scheme mainly relies on frequency band division and does not consider the case of sharing the same frequency band for satellite-to-ground and satellite-to-satellite communication, and does not further design from the comprehensive geometric and power control dimensions such as geometric pointing angle, satellite orbit height, transmission power and ground leakage angle. For example, patent CN109672469A "A non-geostationary satellite-to-geostationary satellite system interference suppression method" calculates the noise margin and allowable interference ratio of the geostationary satellite ground station to determine the avoidance angle of the non-geostationary satellite, and sets an antenna gain suppression zone outside the angle to reduce interference with GSO ground reception. However, this method only performs angle constraint for one-way NGSO and GSO satellite-to-ground link interference, and does not consider the mutual influence of GSO satellite-to-ground link and GSO-NGSO satellite-to-satellite link under the same frequency condition. The above reflects the trend of frequency spectrum sharing, but its technical solution still mainly starts from the power limit angle, and lacks an integrated interference suppression strategy for geometric pointing and power control of inter-satellite and satellite-to-ground, different orbit height NGSO satellites under the same frequency. Therefore, although the existing technology has made some progress in spectrum sharing strategy and basic interference limit, there are still the following main deficiencies: there is no mature scheme for classifying NGSO satellites according to orbit height and defining their pointable angle and ground leakage pointing angle; In the inter-satellite communication and satellite-to-ground communication same frequency scene, there is a lack of complete process based on avoidance angle to select appropriate NGSO-GSO or NGSO-NGSO link to avoid same frequency interference with ground communication. SUMMARY

[0004] The technical problem solved by the present application is to overcome the deficiencies of the prior art. The present application provides a high-low orbit inter-satellite and satellite-to-ground same frequency communication interference suppression method based on avoidance angle.

[0005] The technical solution of the present application is a high-low orbit inter-satellite and satellite-to-ground same frequency communication interference suppression method based on avoidance angle, comprising:

[0006] determining the orbit height h of the NGSO satellite communicating with the GSO satellite;

[0007] calculating the maximum pointable angle according to the orbit height h of the NGSO satellite;

[0008] calculating the half-apex angle γ of the NGSO satellite to the ground;

[0009] traversing the ground test point reaching angle and calculating the related parameters to comprehensively evaluate the interference of different ground positions;

[0010] Calculate the NGSO satellite PFD and compare it with the ground PFD limit value. If it does not meet the requirement, adjust the power to meet the ground PFD limit value.

[0011] Set the inter-satellite link to avoid the satellite-ground link arc Ω. According to the maximum pointing angle of the NGSO satellite, avoid the satellite-ground link avoidance area, select the NGSO satellite that can communicate with the GSO satellite, and realize the inter-satellite communication based on the avoidance angle.

[0012] Further, the maximum pointing angle is calculated according to the orbit height h of the NGSO satellite, which includes:

[0013] When the orbit height of the NGSO satellite is greater than the preset orbit height threshold h th , it is a high-altitude NGSO satellite, and the maximum pointing angle α is calculated:

[0014]

[0015] Where R Earth is the radius of the earth, h GSO is the orbit height of the GSO satellite;

[0016] When the orbit height of the NGSO satellite is less than or equal to the preset orbit height threshold h th , it is a low-altitude NGSO satellite, and the maximum pointing angle β is calculated:

[0017]

[0018] Where h NGSO is the orbit height of the NGSO satellite.

[0019] Further, the preset orbit height threshold range h th is 1000km-2000km.

[0020] Further, the calculation of the half-angle γ of the NGSO satellite to the ground includes:

[0021]

[0022] Where R Earth is the radius of the earth, h NGSO is the orbit height of the NGSO satellite.

[0023] Further, the calculation of the half-angle γ of the NGSO satellite to the ground includes:

[0024] According to the current ground test point arrival angle δ, the current pointing angle θ of the NGSO satellite is calculated:

[0025]

[0026] Calculate the off-axis angle φ of the NGSO satellite transmitting antenna to the ground:

[0027] φ = 180° - γ - θ

[0028] Using the NGSO satellite transmitting antenna pattern, determine each off-axis angle The corresponding gain

[0029] Calculate the slant range d of the NGSO satellite to the ground test point:

[0030]

[0031] Further, the ground test point reaches the angle δ range of 0°-90°.

[0032] Further, the NGSO satellite PFD is calculated, including:

[0033]

[0034] Wherein, the PSD is the NGSO satellite transmitting power spectral density.

[0035] Further, the power adjustment is to adjust the NGSO satellite transmitting PSD by 1dB-5dB each time.

[0036] Further, the inter-satellite communication based on the avoidance angle includes: traversing the NGSO satellite group, excluding the NGSO satellite whose current pointing angle θ is greater than the maximum pointing angle α or β of the NGSO satellite, and excluding the NGSO satellite within the cone whose apex angle is the inter-satellite link link avoidance ground link arc Ω of the GSO ground link, to ensure that the communication direction of the remaining NGSO satellite does not overlap with the ground link.

[0037] A terminal device, comprising: a memory for storing instructions executed by at least one processor; a processor for executing instructions stored in the memory to execute a high-low orbit inter-satellite and satellite-ground same-frequency communication interference suppression method based on the avoidance angle.

[0038] The beneficial effects of the present application compared with the prior art are:

[0039] (1) The present application calculates the maximum pointing angle by orbit height, clearly defines the communication range of available satellites, reduces potential interference, and improves spectrum utilization efficiency; and by traversing the ground test point and dynamically adjusting the transmitting power, the satellite can meet the interference limit requirement in different working states, solve the problem of low-orbit satellite leakage power exceeding the limit, and ensure the stability and safety of system operation.

[0040] (2) The application realizes the compatible coexistence of high and low orbit satellites in the same frequency band for satellite-ground and inter-satellite communication by establishing an integrated same-frequency interference suppression mechanism including orbit height determination, maximum pointable angle calculation, power flux density dynamic control and avoidance angle link selection. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 NGSO that can use satellite-ground communication frequency band and GSO communication is shown in the figure.

[0042] Figure 2 NGSO to ground test point PFD calculation diagram is shown in the figure.

[0043] Figure 3 Inter-satellite same-frequency link avoiding GSO satellite-ground link diagram is shown in the figure.

[0044] Figure 4 Flow chart of method implementation steps is shown in the figure.

[0045] Figure 5 I / N result of not performing inter-satellite and satellite-ground same-frequency link avoidance.

[0046] Figure 6 I / N result of performing inter-satellite and satellite-ground same-frequency link avoidance according to the method. DETAILED DESCRIPTION

[0047] The application will be further explained and described in combination with the accompanying drawings and specific embodiments.

[0048] The application is mainly applied to satellite communication spectrum sharing and interference management technology direction, and can be used in low-orbit broadband communication system, satellite network frequency coordination and inter-satellite link scheduling scenes. The application proposes an inter-satellite and satellite-ground same-frequency communication interference suppression method based on avoidance angle, aiming at the problem that GSO satellite-ground link and GSO-NGSO inter-satellite link use the same frequency and easily produce interference.

[0049] As Figure 1 NGSO that can use satellite-ground communication frequency band and GSO communication is shown in the figure, including GSO satellite, NGSO satellite and NGSO orbit shell layer. The GSO satellite selects the NGSO satellite communication within the maximum pointable angle range. The orbit height h of the NGSO satellite, the current pointing angle θ of the NGSO satellite, the maximum pointable angle α of the NGSO satellite with higher height, and the maximum pointable angle β of the NGSO satellite with lower height are shown in the figure.

[0050] As Figure 2An NGSO-to-ground test point (PFD) calculation diagram showing the geometric parameters needed to calculate the NGSO satellite power reaching the ground, the NGSO satellite orbital height h, the NGSO satellite transmit off-boresight angle φ, the NGSO satellite current pointing angle θ, the NGSO satellite half-angle γ, the slant range d, and the ground test point arrival angle δ are shown in the figure.

[0051] As Figure 3 An inter-satellite co-frequency link avoidance GSO satellite-to-ground link diagram shows the inter-satellite link avoidance satellite-to-ground link avoidance area, which is a conical diagram with the GSO satellite as the vertex, and the inter-satellite link avoidance satellite-to-ground link arc Ω, the twice maximum pointable angle of the lower altitude NGSO satellite 2α, and the NGSO satellite orbital shell are shown in the figure.

[0052] The specific steps of the high-low orbit inter-satellite and satellite-to-ground co-frequency communication interference suppression method based on avoidance angle according to the present application are shown in Figure 4 .

[0053] Step 1: Determine the orbital height of the NGSO satellite in communication with the GSO and calculate the maximum pointable angle.

[0054] First, obtain the orbital height h of the NGSO satellite and compare it with the preset orbital height threshold h th . For example, the threshold value is generally in the range of 1000 km to 2000 km to distinguish between high-altitude and low-altitude NGSO satellites.

[0055] If the NGSO orbital height h is greater than the threshold, calculate the maximum pointable angle α of the high-altitude NGSO satellite. This calculation is based on the geometric relationship between the GSO satellite, the NGSO satellite, and the Earth's surface, as shown in Figure 1 , where the GSO satellite is in a higher orbit and the NGSO satellite is in a lower orbit shell. The maximum pointable angle α is calculated by the triangular relationship,

[0056]

[0057] where R Earth is the Earth's radius, and h GSO is the GSO orbital height.

[0058] If the NGSO orbital height h is less than or equal to the threshold, calculate the maximum pointable angle β of the low-altitude NGSO satellite. This calculation takes into account the Earth's surface tangent restriction, as shown in Figure 1 , where β can be calculated by the following formula,

[0059]

[0060] where h NGSO is the GSO orbital height.

[0061] By this step, NGSO satellites below the threshold can have a larger pointing angle range, so more satellites can communicate with GSO; satellites above the threshold are limited by the GSO and Earth surface tangent, with a smaller pointing angle. As shown in Figure 1 , twice the maximum pointing angle 2β of a lower altitude NGSO satellite can cover a relatively wider access area.

[0062] Second step, calculate the half-angle γ of NGSO satellite to the ground.

[0063] Based on the orbit altitude h of NGSO satellite NGSO and the Earth radius R Earth , calculate the half-angle γ of NGSO satellite to the ground, as shown in Figure 2 . The calculation formula is as follows,

[0064]

[0065] This angle is used to determine the coverage of NGSO satellite signals to the ground in the subsequent step, which ensures that the subsequent PFD calculation considers the field of view angle of the satellite.

[0066] Third step, iterate the ground test point arrival angle and calculate the related parameters

[0067] Iterate the ground test point arrival angle δ from 0° to 90°, with an increment of 1° (i.e. δ = 0°, 1°,..., 90°). For each δ, perform the following 4 steps:

[0068] 1. According to the current δ, calculate the current pointing angle θ of the NGSO satellite, as shown in Figure 2 .

[0069]

[0070] 2. Calculate the off-axis angle φ of the NGSO satellite transmitting antenna to the ground, as shown in Figure 2 .

[0071]

[0072] 3. Use the NGSO satellite transmitting antenna pattern to determine the corresponding gain for each off-axis angle .

[0073] 4. Calculate the slant range d of the NGSO satellite to the ground test point, as shown in Figure 2 .

[0074]

[0075] This step ensures a comprehensive evaluation of interference at different ground locations by iterating.

[0076] Fourthly, calculate the NGSO satellite transmit power spectral density PFD and compare it with the limit value, and adjust the power. For each ground test point angle of arrival δ, the PFD of the NGSO satellite to the ground is calculated according to the following formula.

[0077]

[0078] wherein PSD is the NGSO satellite transmit power spectral density, is the transmit antenna gain in the third step, and d is the slant range.

[0079] Compare the calculated PFD with the ground PFD limit value. If the PFD meets the limit value, go to the fifth step; if it exceeds the limit value, reduce the NGSO satellite transmit PSD (for example, by 1 dB to 5 dB each time), recalculate the PFD, and continue until the limit value is met.

[0080] Fifthly, inter-satellite communication using an avoidance angle. Set the inter-satellite link to avoid the GSO-NGSO link arc Ω, as shown in the following formula. Figure 3 According to the maximum pointing angle (α or β) of the NGSO satellite, avoid the GSO-NGSO link avoidance area, and select the NGSO satellite that can communicate with the GSO. The avoidance area is centered on the GSO satellite, and the NGSO satellite needs to communicate with the GSO in the area outside the pointing angle Ω. The specific selection algorithm is as follows: traverse the NGSO satellite constellation, exclude the satellites with θ > α (or β), and exclude the NGSO satellites within the cone with Ω as the top angle of the GSO satellite-ground link, to ensure that the communication direction of the remaining satellites does not overlap with the satellite-ground link.

[0081] The working principle of the whole method is based on the geometric avoidance area and power control: the inter-satellite communication direction is limited by the maximum pointing angle to avoid signal lateral leakage to other system satellite-ground links; and the PFD adjustment ensures that the ground power limit value is met. The method flow is shown in the following formula. Figure 4 The working principle of the whole method is based on the geometric avoidance area and power control: the inter-satellite communication direction is limited by the maximum pointing angle to avoid signal lateral leakage to other system satellite-ground links; and the PFD adjustment ensures that the ground power limit value is met. The method flow is shown in the following formula.

[0082] A terminal device, comprising: a memory for storing instructions executed by at least one processor; and a processor for executing the instructions stored in the memory to perform a high-low orbit inter-satellite and satellite-ground same-frequency communication interference suppression method based on an avoidance angle. Specific embodiments:

[0084] Consider the scenario of GSO-NGSO link avoiding the GSO satellite-ground link when the GSO system and the NGSO system perform inter-satellite communication, the GSO orbit position is 10°E, the GSO earth station position is (10°E, 0°N), and the NGSO constellation orbit parameters are shown in Table 1.

[0085] Table 1 NGSO constellation orbit parameters

[0086] NGSO constellation system Orbital inclination 53° Total number of orbital planes 32 Number of satellites per orbit 50 Orbital altitude 1150 Minimum elevation angle for terminal communication 0°

[0087] Link Direction GSO Transmit NGSO Receive, GSO Transmit GSO Earth Station Receive, Link RF Parameters as shown in Table 2.

[0088] Table 2 Link RF Parameters

[0089]

[0090]

[0091] h is set th 2000km, then the NGSO system orbit height is 1150km, which belongs to a low orbit height NGSO system, the alpha is calculated as 10.27°, the NGSO cone angle that can communicate with the GSO is 20.54°, the same frequency isolation zone isolation angle Omega is set as 10°, the simulation step is set as 1s, the step number is 86400, the same frequency evaluation index is I / N, and the simulation results of not using the scheme and using the scheme are as shown in Figure 5 and Figure 6 . Figure 5 The I / N results of the GSO space-ground link and the GSO-NGSO inter-satellite link are shown when the GSO space-ground link and the GSO-NGSO inter-satellite link do not perform same frequency link avoidance. Figure 6 The I / N results of the GSO space-ground link and the GSO-NGSO inter-satellite link are shown when the GSO space-ground link and the GSO-NGSO inter-satellite link perform same frequency link avoidance by using the method of the patent, and the avoidance angle is 5°. It can be seen that, compared with Figure 5 , the I / N of the two links is greatly reduced by using the method of the patent, and the same frequency interference is slowed down.

[0092] The application solves the technical problem of same frequency sharing of high-low orbit satellite high orbit space-ground link and inter-satellite link under same frequency communication conditions by using a maximum pointable angle determination method, a ground power limit calculation method and a same frequency avoidance zone design method. 1) The maximum pointable angle calculation by orbit height distinction determines the communication range of the available satellite, and improves the spectrum utilization efficiency. 2) By traversing the ground test points and dynamically adjusting the transmission power, the satellite can meet the interference limit value requirement under different working conditions, and ensure the stability and safety of the system operation. 3) The isolation area is designed by introducing the coordinate system of the earth view angle and the satellite view angle, which realizes real-time geometric avoidance of interference, effectively reduces the same frequency interference between the GSO and the NGSO system, and improves the system spectrum utilization rate and communication reliability.

[0093] Although the present application has been disclosed with reference to the preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application without departing from the technical solutions of the present application shall fall within the protection scope of the technical solutions of the present application.

Claims

1. A method for suppressing interference in high and low orbit inter-satellite and satellite-to-ground co-frequency communication based on avoidance angle, characterized in that, include: Determine the orbital altitude h of the NGSO satellite communicating with the GSO satellite; Calculate the maximum pointing angle based on the NGSO satellite orbital altitude h; Calculate the half-apex angle γ from the NGSO satellite to the ground; The angle of arrival at each ground test point is traversed and relevant parameters are calculated to comprehensively evaluate the interference at different ground locations. Calculate the PFD of the NGSO satellite and compare it with the ground PFD limit. If it does not meet the limit, adjust the power to make it conform to the ground PFD limit. Set the inter-satellite link avoidance arc Ω. Based on the maximum pointing angle of the NGSO satellite, avoid the satellite-to-ground link avoidance zone, select the NGSO satellite that can communicate with the GSO satellite, and realize inter-satellite communication based on the avoidance angle.

2. The method for suppressing interference in high and low orbit inter-satellite and satellite-to-ground co-frequency communication based on avoidance angle as described in claim 1, characterized in that, The calculation of the maximum pointing angle based on the NGSO satellite orbital altitude h includes: When the orbital altitude of the NGSO satellite is greater than the preset orbital altitude threshold h th At that time, it was a relatively high-altitude NGSO satellite. The maximum pointing angle α was calculated as follows: Among them, R Earth h is the Earth's radius. GSO This refers to the orbital altitude of the GSO satellite. When the orbital altitude of the NGSO satellite is less than or equal to the preset orbital altitude threshold h th At that time, it was a low-altitude NGSO satellite. The maximum pointing angle β was calculated as follows: Among them, h NGSO This represents the orbital altitude of the NGSO satellite.

3. The method for suppressing interference in high and low orbit inter-satellite and satellite-to-ground co-frequency communication based on avoidance angle according to claim 2, characterized in that, The preset track height threshold range h th The range is 1000km to 2000km.

4. The method for suppressing interference in high and low orbit inter-satellite and satellite-to-ground co-frequency communication based on avoidance angle as described in claim 1, characterized in that, The calculation of the NGSO satellite's half-apex angle γ to the ground includes: Among them, R Earth h is the Earth's radius. NGSO This represents the orbital altitude of the NGSO satellite.

5. The method for suppressing interference in high and low orbit inter-satellite and satellite-to-ground co-frequency communication based on avoidance angle according to claim 4, characterized in that, The process of traversing the ground test points to reach the angle δ and calculating relevant parameters includes: Calculate the current pointing angle θ of the NGSO satellite based on the current angle of arrival δ of the ground test point: Calculate the off-axis angle φ of the NGSO satellite transmitting antenna to the ground: φ = 180° - γ - θ Use the NGSO satellite transmitting antenna pattern to determine each off-axis angle. Corresponding gain Calculate the slant distance d from the NGSO satellite to the ground test point:

6. The method for suppressing interference in high and low orbit inter-satellite and satellite-to-ground co-frequency communication based on avoidance angle according to claim 5, characterized in that, The range of the arrival angle δ of the ground test point is 0° to 90°.

7. The method for suppressing interference in high and low orbit inter-satellite and satellite-to-ground co-frequency communication based on avoidance angle according to claim 5, characterized in that, Calculating the PFD of NGSO satellites includes: PSD represents the spectral density of the NGSO satellite's launch power.

8. The method for suppressing interference in high and low orbit inter-satellite and satellite-to-ground co-frequency communication based on avoidance angle according to claim 7, characterized in that, The power adjustment mentioned above refers to adjusting the NGSO satellite launch PSD by decreasing it by 1dB to 5dB each time.

9. The method for suppressing interference in high and low orbit inter-satellite and satellite-to-ground co-frequency communication based on avoidance angle according to claim 7, characterized in that, The aforementioned inter-satellite communication based on avoidance angle includes: traversing the NGSO satellite constellation, excluding satellites whose current pointing angle θ is greater than the maximum pointing angle α or β of the NGSO satellite, and simultaneously excluding NGSO satellites within the cone with the radian Ω of the inter-satellite link as the apex angle to avoid the inter-satellite link, ensuring that the communication direction of the remaining NGSO satellites does not overlap with the inter-satellite link.

10. A terminal device, characterized in that, include: Memory, used to store at least one instruction executed by a processor; A processor for executing instructions stored in memory to perform the method as described in any one of claims 1-9.

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