WO2025001497A1 - Method for reducing mutual interference between different low-earth-orbit communication satellite systems - Google Patents

Abstract

Disclosed in the present invention is a method for reducing mutual interference between different low-Earth-orbit communication satellite systems, which can enable different low-Earth-orbit communication satellite systems to share a radio frequency spectrum therebetween. Antenna sub-beams transmitted and received by a first low-Earth-orbit communication satellite system are steerable spot beams, and an on-satellite terminal and a ground terminal thereof have an uplink frequency interference determination function and a downlink frequency interference determination function. For a cooperative second low-Earth-orbit communication satellite system, ephemeris and beam information notification are mutually performed between the first low-Earth-orbit communication satellite system and the second low-Earth-orbit communication satellite system, and the first low-Earth-orbit communication system determines, by means of a beam isolation angle, whether beams of the two systems interfere with each other; and for a non-cooperative second low-Earth-orbit communication satellite system, the first low-Earth-orbit communication satellite system actively performs uplink interference detection and downlink interference detection, and if there is interference, an interfered-with beam is switched to another beam meeting spatial isolation requirements in an adjacent satellite, or the frequency of the interfered-with beam is switched to another frequency. The first and second low-Earth-orbit communication satellite systems complete interference avoidance with respect to a GSO satellite by means of turning off beams in an area which does not meet the lowest isolation angle with respect to the GSO satellite.

Description

A method for reducing mutual interference between different low-orbit communication satellite systems

This application claims priority to a Chinese patent application filed with the Chinese Patent Office on June 30, 2023, with application number 202310800302.6 and invention name “A method for reducing mutual interference between different low-orbit communication satellite systems”, the entire contents of which are incorporated by reference in this application.

Technical Field

The present invention belongs to the technical field of earth orbit communication satellites, and in particular relates to a method for reducing mutual interference between different low-orbit communication satellite systems.

Background Art

Communication satellites receive and send radio signals from the Earth's surface, which is already one of the important applications of space technology. With the advancement of satellite communication technology and the explosion of demand, the value of radio spectrum has become increasingly prominent.

The huge distance between geosynchronous orbit (usually abbreviated as "GSO") satellites and the earth's surface can achieve coverage of a wide area, but for applications such as Internet services, low-orbit satellite constellation systems operating in low-earth orbit (usually abbreviated as "LEO") may be more suitable. Low-orbit satellite constellation systems have the advantages of large system capacity and low latency, and the cost of a single satellite can be reduced through batch production. Specific spectrum resources, such as Ku and Ka bands, are extremely valuable for low-orbit communication satellite systems dedicated to achieving continuous coverage of a certain region or the world.

Generally, LEO satellites in low-orbit communication satellite systems first need to consider how to avoid frequency interference with GSO satellites so that they can share spectrum with many GSO satellites located near the equator. At present, there are corresponding solutions. For example, in the "Beam Constant Bias Shared Radio Spectrum Method and Low-orbit Communication Satellite System (ZL201910630504.4)", when the latitude of the satellite sub-satellite point is 20° (left)/-20° (right), the interfered area within the beam coverage area, when performing interference isolation design between multiple low-orbit communication satellite systems, it is still necessary to first avoid the area where the theoretical serviceable range in the figure interferes with GSO. In the above method, since the trajectory of the GSO satellite sub-satellite point does not move in the direction of the earth's latitude or the movement range is small, the frequency interference avoidance method of the LEO satellite can be designed as a program control logic with the LEO satellite operating latitude as a variable. However, with regard to interference between LEO satellites, on the one hand, the relative operating speed of the LEO satellite is relatively high. On the other hand, multiple LEO communication systems are working, and it is necessary to design a method to reduce interference between low-orbit communication satellite systems that work in high dynamics and full real-time. At present, there is no public method that can reduce beam interference between different low-orbit communication satellite systems so that spectrum can be shared, and can also share spectrum with near-equatorial high-orbit communication satellites (such as GSO satellites).

Summary of the invention

The technology of the present invention solves the problem: overcomes the shortcomings of the prior art and provides a method for reducing mutual interference between different low-orbit communication satellite systems. Under certain rules, different low-orbit communication satellite systems can share spectrum, and can further share spectrum with geostationary orbit satellites.

In order to solve the above technical problems, the present invention discloses a method for reducing mutual interference between different low-orbit communication satellite systems, comprising:

A first low-orbit communication satellite system and a second low-orbit communication satellite system are provided; wherein the second low-orbit communication satellite system is divided into: a cooperative second low-orbit communication satellite system and a non-cooperative second low-orbit communication satellite system;

When the second low-orbit communication satellite system is a cooperative second low-orbit communication satellite system, and it is determined that frequency interference occurs between the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system, a satellite in the first low-orbit communication satellite system or a satellite in the cooperative second low-orbit communication satellite system is selected through a priority control strategy to implement beam switching, and the interfered current beam is switched to other available beams in the adjacent satellite of the selected low-orbit communication satellite system whose beam spatial isolation angle is greater than a set threshold, or the frequency of the interfered current beam is switched to other frequencies that do not interfere with the other party's beam;

When the second low-orbit communication satellite system is a non-cooperative second low-orbit communication satellite system and it is determined that frequency interference occurs between the first low-orbit communication satellite system and the non-cooperative second low-orbit communication satellite system, the interfered current beam is switched to other available beams in the neighboring satellite of the first low-orbit communication satellite system whose beam spatial isolation angle is greater than a set threshold, or the frequency of the interfered beam is switched to other frequencies that do not interfere with the other beam.

In the above method for reducing mutual interference between different low-orbit communication satellite systems,

The first low-orbit communication satellite system includes multiple low-orbit communication satellites A, each of which is equipped with a transmitting user antenna and a receiving user antenna; wherein the transmitting user antenna provides a downlink beam service for the user. The receiving user antenna provides uplink beam services for users; the transmitting user antenna and the receiving user antenna each include a plurality of movable spot beams, each movable spot beam can independently adjust the beam direction to stare at the user's location; each low-orbit communication satellite A of the first low-orbit communication satellite system includes an uplink frequency interference judgment function, and the ground equipment terminal of the first low-orbit communication satellite system includes a downlink frequency interference judgment function;

The second low-orbit communication satellite system includes multiple low-orbit communication satellites B, and each low-orbit communication satellite B is provided with a transmitting user antenna and a receiving user antenna; wherein the transmitting user antenna provides a downlink beam service for the user, and the receiving user antenna provides an uplink beam service for the user.

In the above-mentioned method for reducing mutual interference between different low-orbit communication satellite systems, each satellite in the first low-orbit communication satellite system and the second low-orbit communication satellite system supports the following functions: calculating the beam space isolation angle between the low-orbit communication satellite and the GSO satellite, determining the area where the beam space isolation angle does not meet the set threshold, recorded as area A; closing the low-orbit communication satellite beam in area A to reduce the frequency interference with the GSO satellite.

In the above method for reducing mutual interference between different low-orbit communication satellite systems,

The cooperative second low-orbit communication satellite system refers to: a second low-orbit communication satellite system that can obtain the ephemeris and beam information of the first low-orbit communication satellite system in real time, that is, a second low-orbit communication satellite system that cooperates with the first low-orbit communication satellite system;

A non-cooperative second low-orbit communication satellite system refers to a second low-orbit communication satellite system that cannot obtain each other's ephemeris and beam information in real time with the first low-orbit communication satellite system, that is, a second low-orbit communication satellite system that is non-cooperative with the first low-orbit communication satellite system.

The method for reducing mutual interference between different low-orbit communication satellite systems also includes: formulating a communication protocol to complete real-time notification of ephemeris and beam information between the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system.

The method for reducing mutual interference between different low-orbit communication satellite systems also includes: when the second low-orbit communication satellite system is a cooperative second low-orbit communication satellite system, calculating the spatial isolation angle between different beams of the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system serving the same area; if the frequencies used by the beams of the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system overlap and the spatial isolation angle of the beams is less than a certain set threshold, determining that the first low-orbit communication satellite system is a cooperative second low-orbit communication satellite system. The beams currently in use between the communication satellite system and the cooperative second low-orbit communication satellite system are causing frequency interference to each other.

The method for reducing mutual interference between different low-orbit communication satellite systems mentioned above also includes: when the second low-orbit communication satellite system is a non-cooperative second low-orbit communication satellite system, the first low-orbit communication satellite system determines whether the beam currently being used by the first low-orbit communication satellite system is subject to beam interference from the non-cooperative second low-orbit communication satellite system through the uplink and downlink frequency interference judgment functions of the onboard equipment and ground equipment terminals.

In the above-mentioned method for reducing mutual interference between different low-orbit communication satellite systems, the ephemeris includes: time and position information of the satellite; the beam information includes: beam center position, beam range, beam pointing and frequency information between two low-orbit communication satellite systems.

In the above-mentioned method for reducing mutual interference between different low-orbit communication satellite systems, the beam space isolation angle refers to: when the beams of two satellites provide services to the same position on the ground, the angle between the same position on the ground and the two satellites.

In the above method for reducing mutual interference between different low-orbit communication satellite systems, when the interfered current beam is switched to other available beams in the neighboring satellite whose beam spatial isolation angle is greater than a set threshold, there are:

Determine all satellites in the current low-orbit communication satellite system that can establish a communication link with the ground device terminal, and determine the ephemeris and beam information of each satellite that can establish a communication link with the ground device terminal, and then obtain an available beam set A;

Selecting a number of available beams without frequency interference with the GSO satellite from the available beam set A to obtain an available beam set B;

The available beams in the available beam set B are sorted, and the strategy of satisfying the elevation angle switching threshold, i.e., access, and the available beams that satisfy the dual usage constraints of the communication elevation angle and the number of switching times are preferentially selected.

The present invention has the following advantages:

The present invention discloses a method for reducing mutual interference between different low-orbit communication satellite systems. Under certain rules, different low-orbit communication satellite systems can share spectrum, and can also further share spectrum with geostationary orbit satellites.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flowchart of a method for reducing mutual interference between different low-orbit communication satellite systems according to an embodiment of the present invention;

FIG2 is a schematic diagram of a beam spatial isolation angle in an embodiment of the present invention;

FIG3 is a schematic diagram of interference between beams of different LEO satellites in an embodiment of the present invention;

4 is a schematic diagram of a GSO interference area within a beam coverage area when the latitude of the satellite sub-satellite point is 20° (left)/-20° (right) from a sub-satellite point perspective in an embodiment of the present invention;

FIG5 is a schematic diagram of a constellation configuration of a first low-orbit communication satellite system in an embodiment of the present invention;

FIG6 is a schematic diagram of a constellation configuration of a second low-orbit communication satellite system in an embodiment of the present invention;

7 is a schematic diagram of a first low-orbit communication satellite system satellite spot beam and a second low-orbit communication satellite system beam in an embodiment of the present invention;

8 is a schematic diagram of the distribution of isolation angles of a device terminal position to a first low-orbit communication satellite system satellite and a second low-orbit communication satellite system satellite in an embodiment of the present invention;

FIG9 is a schematic diagram of an available beam area in an embodiment of the present invention;

10 is a schematic diagram of the coverage multiplicity after the first low-orbit communication satellite system and the GSO interference avoidance according to an embodiment of the present invention;

11 is a schematic diagram of the coverage multiplicity after interference avoidance between a second low-orbit communication satellite system and a GSO in an embodiment of the present invention;.

12 is a schematic diagram of satellite switching when a ground terminal (without loss of generality, set to longitude 0° and latitude 0° in the simulation) simultaneously establishes indirect communication with a first low-orbit communication satellite system and a second low-orbit communication satellite system in an embodiment of the present invention;

13 is a schematic diagram of a curve of the cumulative number of switching times under different priority strategies (strategy with the highest elevation angle/strategy with the least number of switching times/strategy with access that meets the elevation angle switching threshold) in an embodiment of the present invention;

14 is a schematic diagram of satellite switching when a ground terminal simultaneously establishes connections with a first low-orbit communication satellite system and a non-cooperative second communication satellite system in an embodiment of the present invention.

DETAILED DESCRIPTION

In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

As shown in FIG1 , in this embodiment, the method for reducing mutual interference between different low-orbit communication satellite systems includes:

Step 1: Set up a first low-orbit communication satellite system and a second low-orbit communication satellite system.

In this embodiment, the first low-orbit communication satellite system and the second low-orbit communication satellite system are defined as follows:

The first low-orbit communication satellite system includes multiple low-orbit communication satellites A, each of which is provided with a transmitting user antenna and a receiving user antenna. The transmitting user antenna provides downlink beam services for users, and the receiving user antenna provides uplink beam services for users; the transmitting user antenna and the receiving user antenna each include a number of movable spot beams, each of which can independently adjust the beam direction to stare at the user's location; each low-orbit communication satellite A of the first low-orbit communication satellite system includes an uplink frequency interference judgment function, and the ground equipment terminal of the first low-orbit communication satellite system includes a downlink frequency interference judgment function.

The second low-orbit communication satellite system includes a plurality of low-orbit communication satellites B, each of which is provided with a transmitting user antenna and a receiving user antenna. The transmitting user antenna provides a downlink beam service for the user, and the receiving user antenna provides an uplink beam service for the user.

Among them, each satellite in the first low-orbit communication satellite system and the second low-orbit communication satellite system supports the following functions: calculating the beam space isolation angle between the low-orbit communication satellite and the GSO satellite, determining the area where the beam space isolation angle does not meet the set threshold, recorded as area A; closing the low-orbit communication satellite beam in area A to reduce the frequency interference with the GSO satellite.

It should be noted that the first low-orbit communication satellite system has no restrictions on the altitude, inclination, right ascension of the ascending node, eccentricity, and argument of perigee of the satellite orbit, and the first low-orbit communication satellite system can provide regional or global multiple coverage services. The second low-orbit communication satellite system has no restrictions on the altitude, inclination, right ascension of the ascending node, eccentricity, and argument of perigee of the satellite orbit, and the second low-orbit communication satellite system can provide regional or global multiple coverage services; in addition, the second low-orbit communication satellite system does not restrict whether the satellite beam is a spot beam.

Furthermore, the second low-orbit communication satellite system can be divided into a cooperative second low-orbit communication satellite system and a non-cooperative second low-orbit communication satellite system according to the interaction with the first low-orbit communication satellite system. Specifically, a cooperative second low-orbit communication satellite system refers to a system that can interact with the first low-orbit communication satellite system. A second low-orbit communication satellite system that can obtain each other's ephemeris and beam information in real time is a second low-orbit communication satellite system that cooperates with the first low-orbit communication satellite system. A non-cooperative second low-orbit communication satellite system refers to a second low-orbit communication satellite system that cannot obtain each other's ephemeris and beam information in real time with the first low-orbit communication satellite system, that is, a second low-orbit communication satellite system that does not cooperate with the first low-orbit communication satellite system.

Preferably, a communication protocol may be formulated to achieve real-time notification of ephemeris and beam information between the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system.

Preferably, the beam space isolation angle refers to: when the beams of two satellites provide services to the same position on the ground, the angle between the same position on the ground and the two satellites, as shown in Figure 2. In Figure 2, 2-110 represents LEO satellite 1, 2-120 represents LEO satellite 2, 2-210 represents beam 1, 2-220 represents beam 2, 2-310 represents a ground station, 2-410 represents the beam space isolation angle of beam 1 and beam 2 to the ground station, and 2-510 represents the surface of the earth.

Preferably, the ephemeris includes but is not limited to: time and position information of the satellite; the beam information includes but is not limited to: beam center position, beam range, beam pointing and frequency information between two low-orbit communication satellite systems.

Step 2: When the second low-orbit communication satellite system is a cooperative second low-orbit communication satellite system and it is determined that frequency interference occurs between the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system, a satellite in the first low-orbit communication satellite system or a satellite in the cooperative second low-orbit communication satellite system is selected through a priority control strategy to implement beam switching, and the interfered current beam is switched to other available beams in the adjacent satellites of the selected low-orbit communication satellite system whose beam spatial isolation angle is greater than a set threshold, or the frequency of the interfered current beam is switched to other frequencies that do not interfere with the other beam.

In this embodiment, when the second low-orbit communication satellite system is a cooperative second low-orbit communication satellite system, it can be determined whether frequency interference occurs between the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system in the following manner: calculate the spatial isolation angle between different beams of the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system serving the same area; if the frequencies used by the beams of the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system overlap and the spatial isolation angle of the beams is less than a set threshold, it is determined that the beams in use between the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system have frequency interference with each other.

Preferably, when the interfered current beam is switched to other available beams in the neighboring satellite of the selected low-orbit communication satellite system whose beam spatial isolation angle is greater than a set threshold, the following method can be used to select other suitable available beams: 1) Determine all satellites in the current low-orbit communication satellite system that can establish a communication link with the ground equipment terminal, and determine the ephemeris and beam information of each satellite that can establish a communication link with the ground equipment terminal, and then obtain the available beam set A. 2) Filter out several available beams that have no frequency interference with the GSO satellite from the available beam set A to obtain the available beam set B. 3) Sort the available beams in the available beam set B, and give priority to the strategy that meets the elevation angle switching threshold, i.e., access, and the available beams that meet the dual usage constraints of the communication elevation angle and the number of switching times.

Step 3, when the second low-orbit communication satellite system is a non-cooperative second low-orbit communication satellite system, and it is determined that frequency interference occurs between the first low-orbit communication satellite system and the non-cooperative second low-orbit communication satellite system, the interfered current beam is switched to other available beams in the neighboring satellite of the first low-orbit communication satellite system whose beam spatial isolation angle is greater than a set threshold, or the frequency of the interfered beam is switched to other frequencies that do not interfere with the other beam.

In this embodiment, when the second low-orbit communication satellite system is a non-cooperative second low-orbit communication satellite system, it can be determined in the following manner whether frequency interference occurs between the first low-orbit communication satellite system and the non-cooperative second low-orbit communication satellite system: the first low-orbit communication satellite system determines whether the beam currently being used by the first low-orbit communication satellite system is subject to beam interference from the non-cooperative second low-orbit communication satellite system through the uplink and downlink frequency interference judgment functions of the onboard equipment and ground equipment terminals.

Preferably, when the interfered current beam is switched to other available beams in the neighboring satellite of the first low-orbit communication satellite system whose beam spatial isolation angle is greater than a set threshold, the following method can be used to select other suitable available beams: 1) Determine all satellites in the current low-orbit communication satellite system that can establish a communication link with the ground equipment terminal, and determine the ephemeris and beam information of each satellite that can establish a communication link with the ground equipment terminal, and then obtain the available beam set A. 2) Filter out several available beams that have no frequency interference with the GSO satellite from the available beam set A to obtain the available beam set B. 3) Sort the available beams in the available beam set B, and give priority to the strategy that meets the elevation angle switching threshold, i.e., access, and the available beams that meet the dual usage constraints of the communication elevation angle and the number of switching times.

Based on the above embodiment, a specific example is given below for explanation.

In this example, the first low-orbit communication satellite system consists of 432 low-orbit communication satellites. The constellation orbit height is 1250km, the number of orbital planes is 24, 18 satellites are evenly distributed in each orbital plane, the phase factor is 1, the orbital inclination is 55°, and the constellation configuration is shown in Figure 5. 5-110 represents the constellation of the first low-orbit communication satellite system. The second low-orbit communication satellite system consists of 144 low-orbit communication satellites, the constellation orbit height is 1450km, the number of orbital planes is 12, 12 satellites are evenly distributed in each orbital plane, the phase factor is 3, and the orbital inclination is 85°. The constellation configuration is shown in Figure 6, and 6-110 represents the constellation of the first low-orbit communication satellite system.

The beam distribution of the first low-orbit communication satellite system and the second low-orbit communication satellite system is shown in Figure 7. In Figure 7, 7-110 represents the satellite spot beam of the first low-orbit communication satellite system, 7-210 represents the satellite beam boundary of the first low-orbit communication satellite system, 7-120 represents the satellite spot beam of the first low-orbit communication satellite system, and 7-220 represents the satellite beam boundary of the first low-orbit communication satellite system.

The interference between beams of different LEO satellites is shown in FIG3. In FIG3, 3-110 represents LEO satellite 1, 3-120 represents LEO satellite 2, 3-210 represents beam 1, 3-220 represents beam 2, 3-310 represents a ground station, 3-410 represents the interference area between beam 1 and beam 2, 3-420 represents the non-interference area between beam 1 and beam 2, 3-510 represents the critical spatial isolation angle of beams corresponding to ground stations in the overlapping area of beam 1 and beam 2, and 3-610 represents a ground station. It should be noted that the non-interference mentioned in the present invention means that the interference between different beams can be reduced to an acceptable level.

When the communication elevation angle of the ground terminal is set to be no less than 15°, the satellite beam boundary half angle of the first low-orbit communication satellite system is 53.86°, and the large arc angle of the ground circle projected by the coverage area is 21.13°; due to the different orbital altitudes of the two constellations, the satellite beam boundary half angle of the second low-orbit communication satellite system is 51.44°, and the large arc angle of the ground circle projected by the coverage area is 23.55°. Within the range of 60° north and south latitude, the minimum coverage multiplicity of the first low-orbit communication satellite constellation is 7, and the minimum coverage multiplicity of the second low-orbit communication satellite constellation is 4.

If the beam boundaries of the first low-orbit communication satellite system and the second low-orbit communication satellite system do not overlap, there is no mutual interference between the first low-orbit communication satellite system and the second low-orbit communication satellite system. If the beam boundaries of the first low-orbit communication satellite system and the second low-orbit communication satellite system overlap, there may be mutual interference in the beam overlap area, and the beam overlap area is shown in Figure 8. In Figure 8, 8-110 represents the satellite beam boundary of the first low-orbit communication satellite system, and 8-120 represents the satellite beam boundary of the second low-orbit communication satellite system. System satellite beam boundary, 8-210 represents the frequency interference area of the two low-orbit communication satellite systems (the critical beam space isolation is set to 14°), and 8-310 represents the frequency interference isolation angle contour of the two low-orbit communication satellite systems. As shown in Figure 8, the frequency interference isolation angle contour of the first low-orbit communication satellite system and the second low-orbit communication satellite system varies from 6° to 24°. The frequency interference isolation angle threshold is set to 14°, and the frequency interference area of the two low-orbit communication satellite systems is shown in the shaded area in Figure 8. The size of the shaded area is related to the distance between the first low-orbit communication satellite system and the second low-orbit communication satellite system. The closer the distance, the larger the area of the shaded area.

Combined with the satellite GSO interference area analysis shown in Figure 4, comprehensive consideration is given to interference avoidance of GSO satellites and reduction of beam interference of adjacent satellites, and the available beam area is shown in Figure 9. In Figure 4, 4-110 represents the beam boundary when the latitude of the satellite sub-satellite point is 20°, 4-210 represents the GSO interference area when the latitude of the satellite sub-satellite point is 20°, 4-310 represents the southeast coordinate system of the satellite sub-satellite point when the latitude of the satellite sub-satellite point is 20°, 4-120 represents the beam boundary when the latitude of the satellite sub-satellite point is -20°, 4-220 represents the GSO interference area when the latitude of the satellite sub-satellite point is -20°, and 4-320 represents the southeast coordinate system of the satellite sub-satellite point when the latitude of the satellite sub-satellite point is -20°. In Figure 9, 9-110 is the satellite beam boundary of the first low-orbit communication satellite system, 9-120 represents the satellite beam boundary of the second low-orbit communication satellite system, 9-210 represents the interference area between the satellite of the first low-orbit communication satellite system and the GSO, 9-220 represents the interference area between the satellite of the second low-orbit communication satellite system and the GSO, 9-310 is the undisturbed area, and 9-410 represents the frequency interference area of the two low-orbit communication satellite systems.

In the beam boundary range shown in FIG9, the “/”-shaped shaded area is the interference area between the first low-orbit communication satellite system satellite and the GSO and the interference area between the first low-orbit communication satellite system satellite and the GSO, and the “×”-shaped shaded area is the frequency interference area between the two low-orbit communication satellite systems. The other blank parts within the beam boundary range are the available beam areas. The available beam areas are changing at every moment, so according to the requirements of the communication satellite system for switching beams, it is necessary to calculate the available beam areas shown in FIG9 in real time before each beam switching to generate the switching satellite number.

For the first low-orbit communication satellite system and the second communication satellite system that can directly or indirectly exchange beam information, the real-time notification of beam information between the two systems is completed; the satellites in the first low-orbit communication satellite system and the satellites in the second low-orbit communication satellite system determine through calculation whether the current beams interfere with each other; the satellites in the first low-orbit communication satellite system or the second low-orbit communication satellite system are clearly identified through priority control. The satellites in the satellite system implement beam switching to switch the interfered beam to an available beam whose beam space isolation angle meets the requirements. The available beams of the satellites in the low-orbit communication satellite system whose beams are to be switched are selected from the available beam area shown in FIG. 9 formed by the two satellites.

For the first low-orbit communication satellite system and the second low-orbit communication satellite system that cannot directly or indirectly exchange beam information, an interference measurement device is added to the ground equipment terminal and onboard equipment of the first low-orbit communication satellite system to detect in real time whether the uplink service or downlink service of the first low-orbit communication satellite of the first low-orbit communication satellite system is interfered with; if interfered with, switch to the available beam in the first low-orbit communication satellite system that meets the requirements of the spatial isolation angle with the current beam. The available beam of the satellite in the first low-orbit communication satellite system to be switched is selected within the available beam area shown in Figure 9 formed by the two satellites. According to the analysis of Figure 9, the area of the unavailable area caused by GSO interference avoidance accounts for about 1/4 to 1/3 of the total beam area, and the area of the unavailable area caused by LEO interference reduction accounts for about 1/6 to 1/5 of the total beam area, and the areas of the two areas are irregular, resulting in irregular shapes of the available areas.

Further, in combination with FIG. 10 and FIG. 11, it can be seen that the coverage multiplicity takes into account the interference avoidance between the low-orbit communication satellite system and the GSO. Some of the users who access the second low-orbit communication satellite system and the first low-orbit communication satellite system are set in the overlapping coverage area. First, the second low-orbit communication satellite system selects an available satellite. After the satellite of the first low-orbit communication satellite system interferes with the satellite of the second low-orbit communication satellite system, the first low-orbit communication satellite system selects the beams of other satellites for coverage through priority control. Due to the limited beam resources, the coverage multiplicity will be reduced. It can be seen that the first low-orbit communication satellite system can still achieve at least one coverage in this area, and most areas have at least 3 to 4 coverages, with the availability of communication services. Among them, in FIG. 10, 10-110 represents the coverage multiplicity, and 10-210 represents the satellite of the first low-orbit communication satellite system. In FIG. 11, 11-110 represents the coverage multiplicity, and 11-210 is the satellite of the first low-orbit communication satellite system.

The satellites of the first low-orbit communication satellite system and the satellites of the second low-orbit communication satellite system can be switched synchronously, as shown in FIG12. FIG12 shows the number table of the satellites accessed by the first low-orbit communication satellite system and the second low-orbit communication satellite system in accordance with the constellation configurations given in FIG5 and FIG6 and the switching strategy proposed by the present invention within a simulation time of 6400 seconds. Without loss of generality, it is assumed in the simulation that the second low-orbit communication satellite system has a higher priority, and the second low-orbit communication satellite system gives priority to satellites with higher elevation angles.

There are three strategies for satellites in the first low-orbit communication satellite system to avoid interference: 1) The first low-orbit communication satellite system gives priority to satellites with higher elevation angles on the basis of satisfying the frequency that can be shared with the second low-orbit communication satellite system; 2) The first low-orbit communication satellite system gives priority to satellites with the least number of switching times on the basis of satisfying the frequency that can be shared with the second low-orbit communication satellite system. 3) Fusion of 1) and 2). Among them, the first strategy selects the accessible satellite with the largest elevation angle in real time, which rapidly increases the number of satellite switching times and reduces the user experience; the second strategy has a relatively large overall communication distance and a large link loss. The third strategy is a fusion of the first two strategies. The first low-orbit communication satellite system, on the basis of satisfying the frequency that can be shared with the second low-orbit communication satellite system, will no longer switch when the switching elevation angle threshold is met. It should be noted that the strategy with the least number of switching times is not the strategy with the lowest elevation angle. The strategy with the lowest elevation angle will also switch in the satellite with the lowest available elevation angle in real time, and the number of switching times is not the smallest.

As can be seen from Figure 12, under the given constellation configuration and switching strategy, the ground station can achieve continuous communication with the first low-orbit communication satellite system and the second low-orbit communication satellite system, and can achieve shared frequencies with the GSO satellite and two different low-orbit communication satellite systems. According to the optimal elevation angle strategy, the switching interval between the ground station and the satellite is as short as a few seconds and as long as more than 100 seconds. Since the optimal elevation angle strategy selects the accessible satellite with the largest elevation angle in real time, the number of satellite switching increases rapidly. Figure 13 is the switching number curve under different priority strategies (optimal elevation angle strategy and minimum switching number strategy). It can be seen from Figure 13 that: 1) In order to pursue the optimal elevation angle at each moment, the number of switching of the highest elevation angle strategy is significantly higher than the number of switching of the minimum switching number strategy; 2) The switching time of the minimum switching number strategy is more than 380 seconds; 3) The switching time and elevation angle change range of the switching elevation angle threshold of 40° are both between the highest elevation angle strategy and the minimum switching number strategy.

For the case of satellite switching when a ground terminal simultaneously establishes connections with the first low-orbit communication satellite system and the non-cooperative second communication satellite system, as shown in Figure 14, in this case, the first low-orbit communication satellite system can only know whether interference has occurred, but cannot know the source of the interference. Assuming that the switching of the second communication satellite system is not frequent, the satellite of the first low-orbit communication satellite system switches among the accessible first low-orbit communication satellite systems according to the third strategy above, and can be accessed and used when the non-interference condition is met.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art may make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the contents of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims (10)

A method for reducing mutual interference between different low-orbit communication satellite systems, characterized by comprising: A first low-orbit communication satellite system and a second low-orbit communication satellite system are provided; wherein the second low-orbit communication satellite system is divided into: a cooperative second low-orbit communication satellite system and a non-cooperative second low-orbit communication satellite system; When the second low-orbit communication satellite system is a cooperative second low-orbit communication satellite system, and it is determined that frequency interference occurs between the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system, a satellite in the first low-orbit communication satellite system or a satellite in the cooperative second low-orbit communication satellite system is selected through a priority control strategy to implement beam switching, and the interfered current beam is switched to other available beams in the adjacent satellite of the selected low-orbit communication satellite system whose beam spatial isolation angle is greater than a set threshold, or the frequency of the interfered current beam is switched to other frequencies that do not interfere with the other party's beam; When the second low-orbit communication satellite system is a non-cooperative second low-orbit communication satellite system and it is determined that frequency interference occurs between the first low-orbit communication satellite system and the non-cooperative second low-orbit communication satellite system, the interfered current beam is switched to other available beams in the neighboring satellite of the first low-orbit communication satellite system whose beam spatial isolation angle is greater than a set threshold, or the frequency of the interfered beam is switched to other frequencies that do not interfere with the other beam. The method for reducing mutual interference between different low-orbit communication satellite systems according to claim 1 is characterized in that: The first low-orbit communication satellite system includes a plurality of low-orbit communication satellites A, each of which is provided with a transmitting user antenna and a receiving user antenna; wherein the transmitting user antenna provides a downlink beam service for the user, and the receiving user antenna provides an uplink beam service for the user; the transmitting user antenna and the receiving user antenna each include a plurality of movable spot beams, and each movable spot beam can independently adjust the beam direction to stare at the user's location; each low-orbit communication satellite A of the first low-orbit communication satellite system includes an uplink frequency interference judgment function, and the ground equipment terminal of the first low-orbit communication satellite system includes a downlink frequency interference judgment function; The second low-orbit communication satellite system includes multiple low-orbit communication satellites B, each of which is equipped with A transmitting user antenna and a receiving user antenna are provided; wherein the transmitting user antenna provides a downlink beam service for the user, and the receiving user antenna provides an uplink beam service for the user. According to the method for reducing mutual interference between different low-orbit communication satellite systems according to claim 1, it is characterized in that each satellite in the first low-orbit communication satellite system and the second low-orbit communication satellite system supports the following functions: calculating the beam space isolation angle between the low-orbit communication satellite and the GSO satellite, determining the area where the beam space isolation angle does not meet the set threshold, recorded as area A; closing the low-orbit communication satellite beam in area A to reduce the frequency interference with the GSO satellite. The method for reducing mutual interference between different low-orbit communication satellite systems according to claim 1 is characterized in that: The cooperative second low-orbit communication satellite system refers to: a second low-orbit communication satellite system that can obtain the ephemeris and beam information of the first low-orbit communication satellite system in real time, that is, a second low-orbit communication satellite system that cooperates with the first low-orbit communication satellite system; A non-cooperative second low-orbit communication satellite system refers to a second low-orbit communication satellite system that cannot obtain each other's ephemeris and beam information in real time with the first low-orbit communication satellite system, that is, a second low-orbit communication satellite system that is non-cooperative with the first low-orbit communication satellite system. The method for reducing mutual interference between different low-orbit communication satellite systems according to claim 1 is characterized in that it also includes: formulating a communication protocol to complete real-time notification of ephemeris and beam information between the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system. According to claim 1, the method for reducing mutual interference between different low-orbit communication satellite systems is characterized in that it also includes: when the second low-orbit communication satellite system is a cooperative second low-orbit communication satellite system, calculating the spatial isolation angle between different beams of the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system serving the same area; if the frequencies used by the beams of the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system overlap and the beam spatial isolation angle is less than a set threshold, it is determined that the beams currently being used by the first low-orbit communication satellite system and the cooperative second low-orbit communication satellite system have frequency interference with each other. The method for reducing mutual interference between different low-orbit communication satellite systems according to claim 1 is characterized in that it also includes: when the second low-orbit communication satellite system is a non-cooperative second low-orbit communication satellite system, the first low-orbit communication satellite system determines whether the beam currently being used by the first low-orbit communication satellite system is interfered by the beam of the non-cooperative second low-orbit communication satellite system through the uplink and downlink frequency interference judgment functions of the on-board equipment and ground equipment terminals. According to the method for reducing mutual interference between different low-orbit communication satellite systems as described in claim 4, it is characterized in that the ephemeris includes: time and position information of the satellite; the beam information includes: beam center position, beam range, beam pointing and frequency information between two low-orbit communication satellite systems. According to the method for reducing mutual interference between different low-orbit communication satellite systems as described in claim 1, it is characterized in that the beam space isolation angle refers to: when the beams of two satellites provide services to the same position on the ground, the angle between the same position on the ground and the two satellites. The method for reducing mutual interference between different low-orbit communication satellite systems according to claim 1 is characterized in that when the interfered current beam is switched to another available beam in an adjacent satellite whose beam spatial isolation angle is greater than a set threshold, there are: Determine all satellites in the current low-orbit communication satellite system that can establish a communication link with the ground device terminal, and determine the ephemeris and beam information of each satellite that can establish a communication link with the ground device terminal, and then obtain an available beam set A; Selecting a number of available beams without frequency interference with the GSO satellite from the available beam set A to obtain an available beam set B; The available beams in the available beam set B are sorted, and the strategy of satisfying the elevation angle switching threshold, i.e., access, and the available beams that satisfy the dual usage constraints of the communication elevation angle and the number of switching times are preferentially selected.