Communication control device and communication control method in satellite communication system

Abstract

To provide a communication control method and device that can quickly implement measures to effectively reduce the effects of obstacles on wireless communication.SOLUTION: A communication control device 100 includes a data storage unit 103 that stores communication quality information that associates communication quality between a satellite and each of a plurality of ground stations with its satellite position, and a processor 102 that, when a communication degradation area where communication quality has deteriorated at a certain satellite position is detected from the communication quality information, estimates the type of obstacle that has deteriorated the communication quality from a deterioration state and time change of the communication degradation area, and selects a measure to avoid the deterioration of communication quality depending on the type of obstacle.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a satellite communication system, and more particularly to a technique for controlling wireless communication between an orbiting satellite and a ground station. [Background technology]

[0002] Generally, in wireless communication, the transmission band can be widened by using a high frequency band, but the tendency of radio waves to travel in a straight line increases. For this reason, some kind of countermeasure is required when an obstacle is present in the wireless communication path. For example, when an obstacle such as a building or tree is present in the line of sight between a non-geostationary satellite and a ground station, problems such as communication disconnection and deterioration of communication quality occur. Therefore, Patent Document 1 discloses a method of handing off a communication link to another non-geostationary satellite in advance to avoid such communication failure when it is predicted that such a communication failure will occur. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2000-513912 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the method described in Patent Document 1, it is necessary to collect obstacle data in advance and create an obstacle map. Therefore, when an object such as space debris or a cloud accidentally appears, the object cannot be recognized as an obstacle, and appropriate measures cannot be taken quickly to reduce the impact of the obstacle on communication.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a communication control method and device that can quickly implement measures to effectively reduce the effects of obstacles on wireless communication. [Means for solving the problem]

[0006] The communication control device disclosed herein is a communication control device that controls wireless communication between at least one satellite orbiting on an orbit at a predetermined speed and a plurality of ground stations in a satellite communication system consisting of the satellite and the plurality of ground stations, and has a communication quality storage unit that accumulates communication quality information that corresponds the communication quality of wireless communication between the satellite and each of the plurality of ground stations to the satellite position, and a processor that controls the wireless communication based on the communication quality information, wherein when the processor detects a communication degradation area where communication quality has deteriorated at a certain satellite position from the communication quality information, it estimates the type of obstacle that has deteriorated the communication quality from the deterioration state and time change of the communication degradation area, and selects a measure to avoid the deterioration of communication quality depending on the type of obstacle. The communication control method disclosed herein is a communication control method for controlling wireless communication between at least one satellite orbiting on an orbit at a predetermined speed and a plurality of ground stations in a satellite communication system consisting of the satellite and the plurality of ground stations, wherein communication quality information that corresponds to the communication quality of wireless communication between the satellite and each of the plurality of ground stations and the satellite position is stored in a communication quality storage unit, and when a processor that controls the wireless communication based on the communication quality information detects a communication degradation area where communication quality has deteriorated at a certain satellite position from the communication quality information, it estimates the type of obstacle that has deteriorated the communication quality from the deterioration state and time change of the communication degradation area, and selects a countermeasure to avoid the deterioration of communication quality depending on the type of obstacle. The program disclosed herein is a program that causes a computer to function as a communication control device that controls wireless communication between at least one satellite orbiting on an orbit at a predetermined speed and multiple ground stations in a satellite communication system consisting of the satellite and multiple ground stations, and realizes in the computer the following functions: storing communication quality information in a communication quality storage unit that corresponds the communication quality of wireless communication between the satellite and each of the multiple ground stations to the satellite position; when a communication degradation area where communication quality has deteriorated at a certain satellite position is detected from the communication quality information, estimating the type of obstacle that has deteriorated the communication quality from the deterioration state and time change of the communication degradation area; and selecting a countermeasure to avoid the deterioration of communication quality depending on the type of obstacle. Effect of the Invention

[0007] According to the present invention, measures can be quickly taken to effectively reduce the influence of obstacles on wireless communication. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a network configuration diagram illustrating a schematic configuration of a satellite communication system according to the present disclosure. [Diagram 2] FIG. 2 is a block diagram illustrating a schematic configuration of a communication control device according to the present disclosure. [Diagram 3] FIG. 3 is a flowchart illustrating a schematic operation of the communication control device according to the present disclosure. [Figure 4] FIG. 4 is a network configuration diagram illustrating a schematic configuration of a satellite communication system according to the first embodiment of the present disclosure. [Diagram 5] FIG. 5 is a block diagram illustrating a schematic configuration of a satellite and a ground station in the satellite communication system according to the first embodiment. [Figure 6] FIG. 6 is a schematic diagram showing an example of a change over time of an obstacle at time T1 in the satellite communication system according to the first embodiment. [Figure 7] FIG. 7 is a schematic diagram showing an example of a change over time of an obstacle at time T2 in the satellite communication system according to the first embodiment. [Figure 8] FIG. 8 is a schematic diagram showing an example of a change over time of an obstacle at time T3 in the satellite communication system according to the first embodiment. [Figure 9] FIG. 9 is a schematic diagram showing an example of a communication quality pattern when an obstacle in the satellite communication system according to the first embodiment is a cloud. [Figure 10] FIG. 10 is a schematic diagram showing an example of a communication quality pattern when an obstacle in the satellite communication system according to the first embodiment is an airplane. [Figure 11]FIG. 11 is a schematic diagram showing an example of a communication quality pattern when an obstacle in the satellite communication system according to the first embodiment is space debris. [Figure 12] FIG. 12 is a flowchart showing an example of an obstacle estimation method in the communication control device according to the first embodiment. [Figure 13] FIG. 13 is a flowchart showing an example of a method for determining a countermeasure in the communication control device according to the first embodiment. [Figure 14] FIG. 14 is a schematic diagram showing a first example of a coping method in the communication control device according to the first embodiment. [Figure 15] FIG. 15 is a schematic diagram showing a second example of the coping method in the communication control device according to the first embodiment. [Figure 16] FIG. 16 is a schematic diagram showing a third example of the coping method in the communication control device according to the first embodiment. [Figure 17] FIG. 17 is a network configuration diagram illustrating a schematic configuration of a satellite communication system according to the second embodiment of the present disclosure. [Figure 18] FIG. 18 is a block diagram illustrating a schematic configuration of a satellite and a ground station in a satellite communication system according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Overview of the embodiment> According to the present disclosure, communication quality information that associates communication quality between a satellite and a ground station with a satellite position is accumulated, and the deterioration state and time change of a communication degradation area are detected using the communication quality information. The type of obstacle is estimated from the deterioration state and time change of the communication degradation area, and a communication quality degradation countermeasure is selected according to the type of obstacle.

[0010] As shown in FIG. 1, there is a satellite C0 in space and multiple (n) ground stations C1 to C2 on the ground. n As an example, the satellite C0 transmits a beam to ground stations C1 to C2 in a coverage area A. nConversely, ground stations C1 to C n Each of these emits an individual transmission beam toward satellite C0, enabling two-way communication.

[0011] In the following figures, due to space limitations, the transmission beam from the transceiver C0 is illustrated as a cone shape with the coverage area A at its base. However, if the satellite C0 is mounted on a low earth orbit (LEO) satellite, it is in an orbit at an altitude of several hundred to several thousand kilometers.

[0012] The satellite C0 may be provided on a specific satellite. For example, if the satellite rotates in a low earth orbit (LEO) at a predetermined period, the satellite C0 may be provided on a specific satellite. n However, it is not limited to a specific satellite. For example, multiple satellites in low orbit may communicate with the same ground stations C1 to C2 every time they reach the same position. n It is possible to communicate with ground stations C1 to C n It is sufficient for the position coordinates of each station to be known, and each station is preferably a fixed station fixed on the earth's surface.

[0013] Such satellite C0 and ground stations C1-C n If an obstacle O comes between the coverage area A and the transmission beam, part of the transmission beam will be attenuated or blocked by the obstacle O, resulting in an area where communication is poor or impossible (hereinafter, communication degradation area R shd Here, the downlink is shown as an example, but the uplink is similar. shd Ground Station C i The communication quality with satellite C0 will deteriorate or communication will become impossible. Therefore, ground stations C1 to C n By monitoring the communication quality of the uplink or downlink between the transceiver C0 and the shd It is possible to detect the occurrence of a noise, its location, and changes in location over time.

[0014] As described in detail below, the communication control device 100 according to the present disclosure collects communication quality information of each transceiver, detects communication degradation areas, estimates the type of obstacle O based on the degradation state and time change of the communication degradation area, and selects a communication degradation countermeasure according to the obstacle type. The communication control device 100 may be provided in a satellite having a satellite C0, or may be provided in ground stations C1 to C2. n Alternatively, the communication control device 100 may be provided in any one of a plurality of ground stations including the ground stations C1 to C2. n In any case, the communication control device 100 is connected to the satellite C0 or the earth stations C1 to C2. n Communication quality information can be obtained from

[0015] 2 and 3, the configuration and functions of the communication control device 100 will be described in detail. Here, an arbitrary satellite C0 is connected to ground stations C1 to C2 within its coverage area A. n An example of communication with the following will be given.

[0016] 2, the communication control device 100 includes a communication unit 101, a processor 102, a data storage unit 103, and a program memory 104. The processor 102 executes a program stored in the program memory 104 to realize functions consisting of a control unit 105, a communication degradation area detection unit 106, an obstacle type estimation unit 107, and a fault countermeasure selection unit 108. The communication control device 100 accumulates communication quality data with ground stations within the coverage area for each satellite's position and time data in the data accumulation unit 103. Based on the accumulated data, the communication control device 100 detects communication degradation areas, estimates the type of obstacle, selects and executes fault avoidance measures, and controls the satellite or ground station.

[0017] 3, the control unit 105 inputs the position and time information of each satellite and the communication quality information between the satellite and each ground station within the coverage area A through the communication unit 101, and stores the information in the data storage unit 103 (operation 201). As the communication quality, for example, the receiving beam intensity at the receiving station, the carrier power to noise power density ratio C / No, etc. can be used.

[0018] The communication degradation area detection unit 106 refers to the accumulated data in the data accumulation unit 103 and detects a communication degradation area R within the coverage area A at a certain satellite position. shd Determine whether or not there is a communication degradation region R shd If there is a communication degradation region R, its degradation state and time change are detected (operation 202). shd The satellite position is fixed point P F Then, one satellite periodically moves to a fixed point P F Each time a fixed point P F Each time it reaches, the communication degradation region R shd The location, deterioration state, and time change of the communication degradation area R shd The time change includes the received beam strength or C / No value of the previously detected communication degradation region R shd The changes in the location and deterioration state of the coverage area A can be detected by comparing the changes in the location and deterioration state of the coverage area A with those of the coverage area B, and include at least one of a change in location (movement speed), a change in size, and a change in deterioration state.

[0019] Next, the obstacle type estimation unit 107 detects the communication degradation area R shd The type of obstacle is estimated based on the deterioration state and time change of the communication degradation area R in the coverage area A (operation 203). shd By comparing the receiving beam intensity in the area with the receiving beam intensity in other areas, the physical properties of the obstacle (electrical properties, in this case, the level of radio wave permeability) can be determined. shd From the speed of movement, it is possible to determine with a certain degree of accuracy whether the obstacle is in outer space, the stratosphere, or the troposphere. Details will be described later.

[0020] When the type of obstacle is estimated, the obstacle countermeasure selection unit 108 selects a countermeasure that can effectively avoid the obstacle caused by the estimated obstacle according to the correspondence data between the obstacle and the countermeasure set in advance, and transmits a control signal to the satellite or the ground station according to the selected countermeasure (operation 204). For example, if the obstacle is an object with high radio wave permeability (such as a cloud made of water droplets), the obstacle can be avoided by increasing the intensity of the transmission beam. If the obstacle is an object with low radio wave permeability (such as an aircraft made of metal, space debris, etc.), the obstacle can be avoided by controlling the diameter of the transmission beam or by changing the transmission path to another satellite or another ground station. Details will be described later.

[0021] More specific communication control will be described in detail below with reference to the drawings. However, the components described in the following embodiments are merely examples, and are not intended to limit the technical scope of the present invention.

[0022] 1. First embodiment 1.1) System configuration FIG. 4 is a schematic diagram of the satellite communication system shown in FIG. 1. In this example, multiple satellites S i and S j The satellite orbits a fixed point P F When the satellite is in the vicinity of the fixed point P, two-way communication with the ground stations B1 to B8 is possible. For the sake of simplicity, it is assumed that the obstacle Ox passes above the ground stations B1 to B8 in sequence or through outer space. The communication control device 100 is as shown in FIG. 2, and the satellite is located at a fixed point P at a predetermined time interval. F Each time it reaches, the communication degradation region R shd Detects the location, deterioration state and changes over time.

[0023] As illustrated in FIG. 4, the communication control device 100 according to this embodiment estimates which of the following three types an obstacle Ox belongs to. Type 1 objects (O1): Space debris of various sizes that travels through space (here, at altitudes of 100 km or more) at speeds of tens of thousands of km per hour (for example, up to 28,800 km or less), and have the physical properties of completely reflecting or absorbing / scattering radio waves. Type 2 objects (O2): Radio-reflecting or radio-scattering aircraft, high-altitude platforms (HAPS), etc., moving above the ground (troposphere, lower stratosphere) at speeds of several hundred kilometers per hour (for example, 100 to 800 km / h). They are about 60 to 100 meters in size and have the physical properties of reflecting or scattering radio waves. Type 3 objects (O3): These are rain clouds and the like that move above the ground (troposphere) at speeds of several tens of kilometers per hour (for example, up to 50 km per hour). They come in a variety of sizes and have the physical property of attenuating radio wave intensity and transmitting it (radio wave attenuation).

[0024] 5, the communication control device 100 may be provided in each satellite S, or in one of the ground stations B. Alternatively, the communication control device 100 may be connected to a network NET to which all the ground stations B are connected. Below, the configurations and functions related to this embodiment in the satellite and the ground station will be roughly described, assuming that the communication control device 100 is provided in the satellite S.

[0025] In FIG. 5, the satellite S has an antenna unit ANT(S), a wireless communication unit 301, a control unit 302, and a communication control device 100. The satellite S can irradiate beams from the antenna unit ANT(S) to each ground station B within its coverage area A, and can receive beams from each ground station B. The antenna unit ANT(S) can change the beamforming angle using a phased array antenna, and can also form a null point in a desired direction within the beam. The beam diameter may also be controlled by increasing or decreasing the number of antenna elements used. The quality of communication with each ground station B can be calculated based on the beam intensity received from each ground station. The communication control device 100 receives satellite position information (fixed point P F ) from the current and past communication quality of each ground station B in the communication degradation region R shdThe deterioration state and time change of are calculated. The satellite S may also have a wireless communication unit and an antenna for communicating with other satellites.

[0026] Each ground station B has an antenna unit ANT(B), a wireless communication unit 401, a control unit 402, and a communication unit 403 for connecting to the network NET. The antenna unit ANT(B) can irradiate a beam to a satellite S and receive a beam from the satellite S. The antenna unit ANT(B) can change the beamforming angle using a phased array antenna, and can also form a null point in a desired direction within the beam. The beam diameter can also be controlled by increasing or decreasing the number of antenna elements used.

[0027] 1.2) Detection of movement speed At a certain position of the satellite S in an orbit, the transmission beam from the satellite S is irradiated to a coverage area A, which includes the ground stations B1 to B8. At this time, a radio wave reflective obstacle Ox moves and blocks a part of the transmission beam. In other words, a communication degradation region R is generated in the coverage area A by the obstacle Ox. shd Even if the satellite S orbits and reaches the position, or if another satellite reaches the position, a communication degradation region R shd If detected, the satellite position is fixed point P F It is identified as:

[0028] As shown in FIG. 6, suppose that an obstacle Ox enters the transmission beam (time T1). The obstacle Ox causes the communication quality between the satellite S and the ground stations B1 and B2 to deteriorate, while the communication quality of the other ground stations B3 to B8 remains good. Therefore, by monitoring the communication quality of the ground stations B1 to B8, the communication deterioration region R at time T1 can be detected. shd The position of is identified.

[0029] Next, as shown in FIG. 7, the satellite S orbits, or another satellite follows the satellite S, to a fixed point P FAt this time, the obstacle Ox degrades the communication quality of only the ground stations B4 and B5. shd Similarly, in the situation illustrated in FIG. 8, the obstacle Ox deteriorates the communication quality of only the ground stations B7 and B8, so that the communication deterioration region R shd The position of is identified.

[0030] Since the intervals between the ground stations B1 to B8 can be determined in advance, the communication degradation region R shd From the travel distance from time T1 to time T2 and the travel distance from time T2 to time T3, it is possible to calculate an approximate travel speed at which the type of obstacle Ox can be identified.

[0031] 1.3) Physical properties of obstacles As shown in Figs. 9 to 11, the communication degradation region R shd The strength of the receiving beam in the area is different from that in other areas. Therefore, the property of the obstacle Ox (radio wave attenuation or radio wave reflection / scattering) can be determined by the value indicating the communication quality.

[0032] As shown in FIG. 9, if the obstacle is a third type object (O3) that transmits radio waves while attenuating them, the communication degradation region R shd The receiving beam strength at the ground stations B3 to B6 is reduced. shd The obstacle O3 is detected as a poor state in which communication is possible but the communication quality is not good. Such an obstacle O3 can be determined to be a rain cloud or the like having physical properties that attenuate radio waves as they pass through.

[0033] As shown in FIG. 10, if the obstacle is a second type object (O2) that reflects or scatters radio waves, the communication degradation region R shd The receiving beam strength at the ground stations B3 to B6 is greatly reduced. shd is detected as a degraded state in which communication is impossible. Such an obstacle O2 can be determined to have physical properties that reflect or scatter radio waves.

[0034] As shown in FIG. 11, if the obstacle is a first-class object (O1) that reflects or scatters radio waves, it will be in the communication degradation region R shd The communication degradation state is such that communication is impossible at the ground stations B3 to B6. Although it can be determined that such an obstacle O1 has physical properties that reflect or scatter radio waves, it is not possible to distinguish between the obstacles O1 and O2 based on the physical properties alone. As described above, even if the obstacles have the same radio wave reflecting / scattering properties, the speed of one is on the order of tens of thousands of kilometers per hour, while the other is on the order of hundreds of kilometers per hour. Therefore, the communication degradation region R shd By comparing the speed of movement, it is possible to determine whether the object is debris-like moving through space or an airplane-like object moving above the ground.

[0035] 1.4) Obstacle type estimation As described above, the data storage unit 103 stores the satellites at fixed points P F The communication quality of each ground station in the coverage area A is acquired each time the ground station reaches the coverage area A, and the acquired communication quality is stored together with time information. The obstacle type estimation unit 107 refers to the data in the data storage unit 103 and estimates the communication degradation area R shd The type of obstacle causing the problem is estimated.

[0036] As illustrated in FIG. 12, the obstacle type estimation unit 107 detects the communication degradation area R shd The communication quality level and the moving speed are input (operation 501), and the obstacle type is determined using the moving speed and physical properties of the obstacle as indices (operation 502).

[0037] Communication degradation area R shd If the moving speed of the obstacle determined from the moving speed of the satellite S is faster than that of the satellite S and the communication quality level is lower than a predetermined value (low radio wave transparency), the obstacle is estimated to be a first type object O1 (operation 503). For example, this is space debris that moves in space at a speed of tens of thousands of kilometers per hour or less.

[0038] Communication degradation area R shdIf the moving speed of the obstacle is slower than that of the satellite S and the communication quality level is lower than a predetermined value (low radio wave transparency), the obstacle is estimated to be a second type object O2 (operation 504). For example, the obstacle is an airplane or a high altitude platform (HAPS) that reflects or scatters radio waves and moves at a speed of several hundred kilometers per hour above the ground (troposphere, lower stratosphere).

[0039] Communication degradation area R shd If the moving speed of the obstacle is slower than that of the satellite S and the communication quality level is higher than a predetermined value (high radio wave transparency), the obstacle is estimated to be a third type object O3 (operation 505). For example, it is a radio wave attenuating rain cloud moving at a speed of several tens of kilometers per hour in the sky above the ground (troposphere).

[0040] For example, if there is one LEO satellite, the fixed point P is sent at intervals of about 90 minutes. F Therefore, it takes 90 minutes x the number of estimated sampling times to estimate the obstacle. In contrast, if there are eight LEO satellites, these satellites reach fixed point P at intervals of about 90 / 8 = 11.25 minutes. F Since the obstacles are detected sequentially, the time required for obstacle detection can be reduced to 11.25 minutes × the number of estimated sampling times.

[0041] 1.5) Choosing a solution to avoid obstacles The obstacle avoidance countermeasure selection unit 108 selects an obstacle avoidance countermeasure according to the obstacle type estimated by the obstacle type estimation unit 107. Hereinafter, a flow of the obstacle avoidance countermeasure and examples of the countermeasure will be described with reference to Fig. 13 and Figs. 14 to 16.

[0042] 13, the obstacle countermeasure selection unit 108 inputs the obstacle type estimated by the obstacle type estimation unit 107 (operation 601), and selects and executes the optimal countermeasure according to the obstacle type. shd For example, as shown in FIG. 14, a large debris O1 is located on a satellite S iIf all transmission beams from the satellite S are blocked and communication deteriorates throughout the coverage area A, communication cannot be restored by complementary beams from other satellites. j As a countermeasure against the failure, irradiation of an alternative transmission beam from the coverage area A is selected (operation 603), thereby making it possible to restore communication throughout the coverage area A.

[0043] Communication degradation area R shd If the obstacle is a part of the coverage area A, it is determined that the obstacle can be complemented (YES in operation 602), and the same measures as those in the case where the obstacle is estimated to be the second type object O2 can be selected (operation 604). The failure recovery measures (operation 604) in the case where the obstacle is estimated to be the second type object O2 are as follows.

[0044] As a fault avoidance measure, one of the following a) to d) or a combination of these can be selected.

[0045] <Countermeasure a: Changing the direction of the transmission beam> The beamforming angle is changed to other satellites or other ground stations to irradiate the complementary beam. This creates a route to bypass the obstacle and eliminates the communication degradation area R. shd The communication quality can be restored. In this case, the complementary beam may be emitted not only from a satellite in the same orbit but also from a satellite in a different orbit. Also, when one antenna is responsible for multiple beams, the level distribution between the beams may be changed. Two complementary examples are shown in Figures 15 and 16.

[0046] In FIG. 15, satellite S i The beam transmitted from is partially blocked by an obstacle Ox and communication is degraded in the region R. shd If this occurs, satellite S i From a satellite in a different orbit j Response information is sent to the satellite S j From the communication degradation region R shd It is possible to emit a complementary beam to the target.

[0047] In Fig. 16, the communication degradation area Rshd The ground stations B4 and B5 in the satellite S may notify a good ground station (e.g., B7) of the communication degradation. In this case, the ground station B7 notifies the satellite S i The handling information will be sent via satellite S j From the communication degradation region R shd It is also possible to emit a complementary beam to the target.

[0048] <Countermeasure b: Changing the beam diameter> The transmission beam diameter can be controlled by increasing or decreasing the number of elements used in the phased array antenna in the antenna section ANT of the satellite S or the ground station B. This allows the communication degradation region R shd This may improve the communication quality.

[0049] <Countermeasure c: Change of frequency or frequency band> The wireless communication unit 301 of the satellite S or the wireless communication unit 401 of the ground station B changes the carrier frequency to a lower frequency band that can get around obstacles. shd In some cases, it may be possible to improve the communication quality of the wireless LAN. It is also possible to improve the signal-to-noise ratio (SNR) by narrowing the frequency band.

[0050] <Measure d: Selective suppression of transmission beam intensity> Communication degradation area R shd The output level of the transmission beam in the direction corresponding to the obstacle is reduced. This selective reduction of the transmission output can be achieved by creating a null point. A beam irradiated to a radio wave reflective / scattering obstacle is reflected or scattered by the obstacle, which may cause radio wave interference with other satellites or ground stations. By creating a null point and suppressing the beam intensity in the direction corresponding to the obstacle position, such radio wave interference can be suppressed.

[0051] 13, when the obstacle is estimated to be the third object O3, the obstacle countermeasure selection unit 108 selects, as the obstacle avoidance countermeasure, one of the above countermeasures a) to c) and the countermeasure e) described below, or a combination of these (operation 605). This makes it possible to restore communication throughout the coverage area A.

[0052] <Measure e: Increasing transmission beam strength> When the obstacle is a third-class object such as a cloud that attenuates radio waves while passing through, the communication degradation region R shd Increase the output of the transmission beam in the direction corresponding to the obstacle to the extent that the obstacle is eliminated. This is the simplest and most effective countermeasure, since it only involves increasing the transmission output level. If countermeasure e does not work, it is desirable to implement countermeasures a) to c) described above.

[0053] 1.6) Effects As described above, according to this embodiment, the type of obstacle is estimated from the degradation state and time change of the communication degradation area detected based on the communication quality information between the satellite and the ground station, and a countermeasure against degradation of communication quality is selected according to the type of obstacle. In this way, by roughly estimating the type of obstacle based only on the communication quality information, it becomes possible to quickly select an effective countermeasure according to the type. This makes it possible to effectively improve the degradation of communication quality caused by the presence of an obstacle, and to quickly implement the optimal countermeasure against the failure.

[0054] In addition, because countermeasures against failures can be selected from communication quality information, there is no need for special sensors or advanced calculations such as image analysis, which reduces power consumption, response time, satellite weight, and costs.

[0055] In addition, when multiple satellites are orbiting the same low orbit, the satellite S i is the communication degradation region R shd The position where the F ) and obtains communication quality information at that time. i The acquired communication quality information is then sent to the fixed point P F Satellite S coming to j This allows the satellite S j The communication quality information acquired by the satellite S iBy comparing the communication quality information received from the satellite with the communication quality information received from the satellite, it is possible to more efficiently detect communication degradation areas, estimate the type of obstacle, and select measures to deal with communication degradation. In this case, the communication quality information between satellites may be exchanged by an inter-satellite communication unit provided in each satellite, or via a ground station.

[0056] 2. Second embodiment In the above-mentioned first embodiment, centralized control is adopted in which the communication control device 100 provided in the satellite or the ground station executes the above-mentioned functions (collection of communication quality information, detection of communication degradation areas, estimation of obstacle types, and selection of communication degradation countermeasures). However, the present invention is not limited to this, and distributed control can also be adopted. Hereinafter, with reference to Figs. 17 and 18, a second embodiment will be described in which communication control devices provided in multiple satellites respectively share communication quality information with each other to realize the above-mentioned functions.

[0057] As shown in FIG. 17 and FIG. 18, a plurality of satellites S1, S2, . . . revolve around the Earth E in a non-geostationary orbit. i The satellite S has an antenna unit ANT(1) for communicating with a ground station, an inter-satellite communication unit 303 and an antenna unit ANT(2) for communicating with at least one adjacent satellite, and a communication control device 100(i) having the same functions as the communication control device 100 illustrated in FIG. i The other configurations of the satellite S shown in FIG. 18 are basically the same as those of the satellite S shown in FIG. 5, so the same reference numerals are used and the description is omitted. j Satellite S i The satellite S i However, for convenience of explanation, only the communication control device 100 is distinguished by the subscripts (i) and (j).

[0058] Satellite S i As already explained, the communication control device 100(i) provided in the coverage area A accumulates communication quality information Q(Ai) between the coverage area A and the ground station, and determines a communication degradation region R based on the accumulated data. shdThe communication control device 100(i) detects the obstacle, estimates the type of obstacle, and selects a countermeasure against communication degradation. Furthermore, the communication control device 100(i) transmits communication quality information Q(Ai) from the antenna unit ANT(2) to the fixed point P F Satellite S coming to j Send to.

[0059] Satellite S j The communication control device 100(j) of the satellite S i The satellite S stores the communication quality information Q(Ai) received from the satellite S, and further stores the communication quality information Q(Aj) in the coverage area A that it has acquired. j The communication control device 100(j) of the first embodiment compares the communication quality information Q(Aj) it has acquired with the information on the communication quality of the satellite S i By comparing the communication quality information Q(Ai) received from the communication quality information receiving unit 10 with the communication quality information Q(Ai) received from the communication quality information receiving unit 10, it is possible to more efficiently detect communication degradation areas, estimate the type of obstacle, and select measures to deal with communication degradation.

[0060] Furthermore, the communication control device 100(j) transmits communication quality information Q(Ai) and Q(Aj) from the antenna unit ANT(2) to the fixed point P F The next satellite coming to k In the same manner, the accumulated data is transferred to the succeeding satellites, and the fixed point P F This allows each satellite to roughly estimate the type of obstacle based only on the communication quality information, and quickly select effective measures according to that type.

[0061] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-mentioned embodiments. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be appropriately combined with other embodiments.

[0062] 3. Notes A part or all of the above-described embodiment and examples may be described as follows, but is not limited to these. (Appendix 1) A communication control device for controlling wireless communication between at least one satellite orbiting in an orbit at a predetermined speed and a plurality of ground stations in a satellite communication system comprising the satellite and the plurality of ground stations, comprising: a communication quality storage unit that accumulates communication quality information that associates a communication quality of wireless communication between the satellite and each of the plurality of ground stations with a satellite position; a processor for controlling the wireless communication based on the communication quality information; wherein the processor: When a communication degradation area where communication quality has been degraded at a certain satellite position is detected from the communication quality information, a type of obstacle that has degraded the communication quality is estimated from a degradation state and a change over time of the communication degradation area; selecting a measure to avoid the deterioration of the communication quality according to the type of the obstacle; Communications control device. (Appendix 2) The processor, Estimating a physical property of the obstacle from a degradation state of the communication degradation area, and estimating a moving speed of the obstacle from a time change of the communication degradation area; The communication control device according to claim 1, further comprising: estimating a type of the obstacle from a physical property and the moving speed of the obstacle. (Appendix 3) The processor, If the moving speed of the obstacle is faster than the predetermined speed, the obstacle is estimated to be a first type object existing in outer space; If the moving speed of the obstacle is slower than the predetermined speed, it is assumed to be an aerial object existing above the ground at an altitude lower than that of outer space. 3. A communication control device as claimed in claim 2. (Appendix 4) The processor, If the degradation state of the communication degradation area is greater than a predetermined level, the object in the sky is estimated to be a second type object having radio wave reflecting or scattering properties; If the degradation state of the communication degradation area is smaller than a predetermined level, the object in the sky is estimated to be a third type object having radio wave attenuation properties. 4. A communication control device according to claim 3. (Appendix 5) A communication control device as described in Appendix 4, wherein, when the processor estimates that the object is a third type object, the output level of the transmission beam of the wireless communication is increased to a level at which the communication quality of the communication degradation area is good. (Appendix 6) A communication control device described in any one of Appendices 3-5, wherein when the processor estimates that the obstacle is the first type object or the second type object, wireless communication is performed between another satellite and the communication degradation area using a complementary beam. (Appendix 7) The communication control device according to any one of appendices 1 to 6, wherein the processor selects at least one countermeasure from a plurality of countermeasures for avoiding deterioration of the communication quality according to a type of the obstacle. (Appendix 8) The plurality of measures include: A method for increasing the output level of a transmission beam corresponding to the communication degradation area; A method for reducing the output level of a transmission beam corresponding to the communication degradation area; A method for reducing the frequency band used in said wireless communication; A method of changing the direction of a transmission beam corresponding to the communication degradation area to another satellite or another ground station outside the communication degradation area, and passing the beam through the other satellite or the other ground station; A method for narrowing or widening the beam diameter of a transmission beam corresponding to the communication degradation area, 8. The communication control device according to claim 7, (Appendix 9) A communication control device according to any one of appendixes 1 to 4, provided in the at least one satellite. (Appendix 10) 7. A communication control device according to any one of claims 1 to 6, provided in at least one of the plurality of ground stations and communicatively connected to the plurality of ground stations. (Appendix 11) A communication control method for controlling wireless communication between at least one satellite orbiting in an orbit at a predetermined speed and a plurality of ground stations in a satellite communication system comprising the satellite and the plurality of ground stations, comprising: storing communication quality information in a communication quality storage unit, the communication quality information correlating the communication quality of the wireless communication between the satellite and each of the plurality of ground stations with the satellite position; a processor that controls the wireless communication based on the communication quality information, When a communication degradation area where communication quality has been degraded at a certain satellite position is detected from the communication quality information, a type of obstacle that has degraded the communication quality is estimated from a degradation state and a change over time of the communication degradation area; selecting a countermeasure for avoiding the deterioration of the communication quality according to the type of the obstacle; Communications control method. (Appendix 12) The processor, Estimating a physical property of the obstacle from a degradation state of the communication degradation area, and estimating a moving speed of the obstacle from a time change of the communication degradation area; A communication control method according to claim 11, further comprising estimating a type of the obstacle from a physical property and the moving speed of the obstacle. (Appendix 13) The processor, If the moving speed of the obstacle is faster than the predetermined speed, the obstacle is estimated to be a first type object existing in outer space; If the moving speed of the obstacle is slower than the predetermined speed, it is assumed to be an aerial object existing above the ground at an altitude lower than that of outer space. 13. The communication control method according to claim 12. (Appendix 14) The processor, If the degradation state of the communication degradation area is greater than a predetermined level, the object in the sky is estimated to be a second type object having radio wave reflecting or scattering properties; If the degradation state of the communication degradation area is smaller than a predetermined level, the object in the sky is estimated to be a third type object having radio wave attenuation properties. 14. The communication control method according to claim 13. (Appendix 15) A communication control method as described in Appendix 14, wherein, when the processor estimates that the object is a third type object, the output level of the transmission beam of the wireless communication is increased to a level at which the communication quality of the communication degradation area is good. (Appendix 16) A communication control method described in any one of Appendices 13-15, wherein when the processor estimates that the obstacle is the first type object or the second type object, wireless communication is performed between another satellite and the communication degradation area using a complementary beam. (Appendix 17) The communication control method according to any one of appendices 11-16, wherein the processor selects at least one countermeasure from a plurality of countermeasures for avoiding deterioration of the communication quality according to a type of the obstacle. (Appendix 18) The plurality of measures include: A method for increasing the output level of a transmission beam corresponding to the communication degradation area; A method for reducing the output level of a transmission beam corresponding to the communication degradation area; A method for reducing the frequency band used in said wireless communication; A method of changing the direction of a transmission beam corresponding to the communication degradation area to another satellite or another ground station outside the communication degradation area, and passing the beam through the other satellite or the other ground station; A method for narrowing or widening the beam diameter of a transmission beam corresponding to the communication degradation area, 18. The communication control method according to claim 17, (Appendix 19) A communication control method according to any one of appendices 11-16, which is executed by a communication control device provided in one satellite or one ground station under centralized control. (Appendix 20) A communication control method according to any one of appendices 11-16, which is executed by a communication control device provided in each of a plurality of satellites through distributed control. (Appendix 21) A program for causing a computer to function as a communication control device for controlling wireless communication between at least one satellite orbiting in an orbit at a predetermined speed and a plurality of ground stations in a satellite communication system comprising the satellite and the plurality of ground stations, the program comprising: a function of storing, in a communication quality storage unit, communication quality information that associates a communication quality of wireless communication between the satellite and each of the plurality of ground stations with a satellite position; a function of, when detecting a communication degradation area in which communication quality is degraded at a certain satellite position from the communication quality information, estimating a type of obstacle that has degraded the communication quality from a degradation state and a change over time of the communication degradation area; A function of selecting a countermeasure for avoiding deterioration of the communication quality according to a type of the obstacle; A program for realizing the above on the computer. (Appendix 22) At least one satellite orbiting at a predetermined speed; A plurality of ground stations; a communication control device for controlling wireless communication between the satellite and the plurality of ground stations; The communication control device, storing communication quality information in which the communication quality of wireless communication between the satellite and each of the plurality of ground stations is associated with a satellite position; When a communication degradation area where communication quality has been degraded at a certain satellite position is detected from the communication quality information, a type of obstacle that has degraded the communication quality is estimated from a degradation state and a change over time of the communication degradation area; selecting a measure to avoid the deterioration of the communication quality according to the type of the obstacle; Satellite communication system. [Industrial Applicability]

[0063] The present invention is applicable to a satellite communication system that controls wireless communication between an orbiting satellite and a ground station. [Explanation of symbols]

[0064] 100, 100(i), 100(j) Communication control device 101 Communications Department 102 processors 103 Data Storage Unit 104 Program Memory 105 Control section 106 Communication Degradation Area Detection Unit 107 Obstacle type estimation section 108 Troubleshoot Selection Section A. Coverage Area B1~B8, C1~C n Ground Station C0, S i , S j satellite O1 1st type object O2 2nd type object O3 3rd type object Ox Obstacle R shd Communication degradation area

Claims

1. A communication control device for controlling wireless communication between at least one satellite orbiting in an orbit at a predetermined speed and a plurality of ground stations in a satellite communication system comprising the satellite and the plurality of ground stations, comprising: a communication quality storage unit that accumulates communication quality information that associates a communication quality of wireless communication between the satellite and each of the plurality of ground stations with a satellite position; a processor for controlling the wireless communication based on the communication quality information; wherein the processor: When a communication degradation area where communication quality has been degraded at a certain satellite position is detected from the communication quality information, a type of obstacle that has degraded the communication quality is estimated from a degradation state and a change over time of the communication degradation area; selecting a measure to avoid the deterioration of the communication quality according to the type of the obstacle; Communications control device.

2. The processor, Estimating a physical property of the obstacle from a degradation state of the communication degradation area, and estimating a moving speed of the obstacle from a time change of the communication degradation area; The communication control device according to claim 1 , wherein a type of the obstacle is estimated from a physical property and the moving speed of the obstacle.

3. The processor, If the moving speed of the obstacle is faster than the predetermined speed, the obstacle is estimated to be a first type object existing in outer space; If the moving speed of the obstacle is slower than the predetermined speed, it is assumed to be an aerial object existing above the ground at an altitude lower than that of outer space. The communication control device according to claim 2.

4. The processor, If the degradation state of the communication degradation area is greater than a predetermined level, the object in the sky is estimated to be a second type object having radio wave reflecting or scattering properties; If the degradation state of the communication degradation area is smaller than a predetermined level, the object in the sky is estimated to be a third type object having radio wave attenuation properties. The communication control device according to claim 3.

5. The communication control device according to claim 4 , wherein when the processor estimates that the object is the third type object, it increases the output level of the transmission beam of the wireless communication to a level at which the communication quality in the communication degradation area is good.

6. A communication control device described in any one of claims 3 to 5, wherein when the processor estimates that the obstacle is the first type object or the second type object, wireless communication is performed between another satellite and the communication degradation area using a complementary beam.

7. The communication control device according to any one of claims 1 to 4, wherein the processor selects at least one measure from a plurality of measures for avoiding deterioration of the communication quality in accordance with a type of the obstacle.

8. The plurality of measures include: - a method for increasing the power level of a transmission beam corresponding to the communication degradation area; - A method for reducing the output level of a transmission beam corresponding to the communication degradation area; A method for reducing the frequency band used in said wireless communication; A method of changing the direction of a transmission beam corresponding to the communication degradation area to another satellite or another ground station outside the communication degradation area, and passing the beam through the other satellite or the other ground station; and A method for narrowing or widening the beam diameter of a transmission beam corresponding to the communication degradation area, The communication control device according to claim 7 ,

9. A communication control method for controlling wireless communication between at least one satellite orbiting an orbit at a predetermined speed and a plurality of ground stations in a satellite communication system, the method comprising: storing communication quality information in a communication quality storage unit, the communication quality information correlating the communication quality of the wireless communication between the satellite and each of the plurality of ground stations with the satellite position; a processor that controls the wireless communication based on the communication quality information, When a communication degradation area where communication quality has been degraded at a certain satellite position is detected from the communication quality information, a type of obstacle that has degraded the communication quality is estimated from a degradation state and a change over time of the communication degradation area; selecting a countermeasure for avoiding the deterioration of the communication quality according to the type of the obstacle; Communications control method.

10. A program for causing a computer to function as a communication control device for controlling wireless communication between at least one satellite orbiting an orbit at a predetermined speed and a plurality of ground stations in a satellite communication system comprising the satellite and the plurality of ground stations, the program comprising: a function of storing, in a communication quality storage unit, communication quality information that associates a communication quality of wireless communication between the satellite and each of the plurality of ground stations with a satellite position; a function of, when detecting a communication degradation area in which communication quality is degraded at a certain satellite position from the communication quality information, estimating a type of obstacle that has degraded the communication quality from a degradation state and a change over time of the communication degradation area; A function of selecting a countermeasure for avoiding deterioration of the communication quality according to a type of the obstacle; A program for realizing the above on the computer.

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