Satellite antenna control device, control station, and satellite antenna control method

Abstract

To provide a satellite communication optimized for users.SOLUTION: A control station 110 selects a subchannel to be occupied by a user 101 as an assigned channel from among subchannels included in the communication band of a channelizer mounted on a communication satellite 200. The control station 110 determines, on the basis of position information of the user 101, an excitation coefficient to be given to one or more element antennas that form a composite beam of the assigned channel among the element antennas constituting an array antenna mounted on the communication satellite 200.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for controlling an antenna onboard a communications satellite. [Background technology]

[0002] In recent years, with the demand for larger capacity in satellite communications, multi-beam satellites called HTS have been developed, which are capable of transmitting and receiving signals using multiple beams. HTS is an abbreviation for High Throughput Satellite.

[0003] DBF and digital channelizers are often used for multi-beam forming in HTS. DBF is a type of antenna control method. An antenna device that forms a desired directivity (synthetic beam) by combining the input or output of multiple element antennas is called an array antenna. In particular, a method that digitally implements a combining circuit that applies a weighting coefficient (excitation coefficient) to the input and output of each antenna using software is called DBF. Compared to conventional synthesis methods using analog circuits, DBF allows greater freedom in weighting coefficients, which increases the flexibility of the directivity that can be achieved. A digital channelizer is a device that uses digital circuits to allocate input and output signals to divided bands (subchannels) within a communication band and adjust the signal paths. DBF is an abbreviation for Digital Beam Forming.

[0004] By combining DBF and a digital channelizer to flexibly switch signal transmission / reception paths and synthesized beams, efficient communications become possible. Patent Document 1 discloses a method for improving communication conditions by changing the synthesized beam and communication band using a DBF and digital channelizer mounted on a satellite based on an index indicating the communication conditions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2020 / 225903 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally, location information of users who perform satellite communications has not been particularly utilized. Instead, the composite beam is designed to provide a trouble-free communication environment for users within a coverage area called the EOC. However, there are limitations to the performance of communication devices that can be used in the special environment of space, and as a result, communication can become unstable depending on weather conditions. EOC is an abbreviation for Edge of Coverage.

[0007] The present disclosure aims to provide optimal satellite communications to users within an EOC. [Means for solving the problem]

[0008] The satellite antenna control device of the present disclosure includes: a channel allocation unit that selects a subchannel to be occupied by a user as an allocation channel from among subchannels included in a communication band of a channelizer mounted on the communication satellite; and a beam forming unit that determines, based on the user's position information, excitation coefficients to be applied to each of one or more element antennas that form a composite beam of the assigned channel among the element antennas that make up the array antenna mounted on the communication satellite. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide optimal satellite communications to users within the EOC. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a configuration diagram of a satellite communication system 100 according to a first embodiment. [Figure 2] FIG. 2 is a configuration diagram of a communication satellite 200 according to the first embodiment. [Figure 3] FIG. 2 is a configuration diagram of a satellite antenna control device 300 according to the first embodiment. [Figure 4] 1 is a schematic diagram of conventional beam forming; [Figure 5] FIG. 3 is a schematic diagram of beam forming according to the first embodiment. [Figure 6] 3 is a flowchart of a satellite antenna control method according to the first embodiment. [Figure 7] FIG. 11 is a configuration diagram of a satellite antenna control device 300 according to a third embodiment. [Figure 8] 10 is a flowchart of a satellite antenna control method according to the third embodiment. [Figure 9] FIG. 10 is a configuration diagram of a satellite antenna control device 300 according to a fourth embodiment. [Figure 10] 10 is a flowchart of a satellite antenna control method according to the fourth embodiment. [Figure 11] 13 is a flowchart of a satellite antenna control method according to the fifth embodiment. [Figure 12] 13 is a flowchart of a satellite antenna control method according to the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] In the embodiments and drawings, the same or corresponding elements are denoted by the same reference numerals. The description of elements denoted by the same reference numerals as those already described will be omitted or simplified as appropriate. Arrows in the drawings primarily indicate the flow of data or the flow of processing.

[0012] Embodiment 1 The satellite communication system 100 will be described with reference to FIGS.

[0013] ***Configuration Description*** The configuration of a satellite communication system 100 will be described with reference to FIG. The satellite communication system 100 is a system that provides satellite communications to a user 101 . A user 101 uses a communication device 102 to access satellite communications.

[0014] The satellite communication system 100 includes a communication satellite 200 and an earth station. An earth station is a facility located on the ground of the Earth. Specifically, the satellite communication system 100 includes earth stations such as a control station 110 and a gateway station 120.

[0015] The communication satellite 200 is an artificial satellite for satellite communications. Communications satellite 200 may be any satellite equipped with DBF capabilities and a digital channelizer. The orbit of the communications satellite 200 may be any orbit, such as LEO, MEO, or GEO. LEO is an abbreviation for Low Earth Orbit. MEO is an abbreviation for Middle Earth Orbit. GEO is an abbreviation for Geostationary Earth Orbit.

[0016] The control station 110 includes a satellite antenna control device 300 and controls the communication satellite 200 via the gateway station 120 . The gateway station 120 includes a communication device 121 and communicates with the communication satellite 200. The gateway station 120 is also called a TTC station. TTC is an abbreviation for Telemetry, Tracking and Control.

[0017] The configuration of the communications satellite 200 will be described with reference to FIG. The communication satellite 200 includes a communication device 201 . The communication device 201 includes an array antenna 210S, an array antenna 210R, a channelizer 220, and a control device 230. The array antenna 210S is a transmitting array antenna 210. The array antenna 210S includes a plurality of element antennas 211S. The element antennas 211S are element antennas 211 of the array antenna 210S. The array antenna 210R is a receiving array antenna 210. The array antenna 210R includes a plurality of element antennas 211R. The element antennas 211R are element antennas 211 of the array antenna 210R. The channelizer 220 is a digital channelizer. The control device 230 controls the array antenna 210S, the array antenna 210R, and the channelizer 220. The control device 230 has a DBF function.

[0018] The configuration of the satellite antenna control device 300 will be described with reference to FIG. The satellite antenna control device 300 is a computer that includes hardware such as a processor 301, a memory 302, an auxiliary storage device 303, a communication device 304, and an input / output interface 305. These pieces of hardware are connected to one another via signal lines.

[0019] The processor 301 is an IC that performs arithmetic processing and controls other hardware. For example, the processor 301 is a CPU. IC is an abbreviation for Integrated Circuit. CPU is an abbreviation for Central Processing Unit.

[0020] The memory 302 is a volatile or non-volatile storage device. The memory 302 is also called a primary storage device or a main memory. For example, the memory 302 is a RAM. Data stored in the memory 302 is saved in the secondary storage device 303 as needed. RAM is an abbreviation for Random Access Memory.

[0021] The auxiliary storage device 303 is a non-volatile storage device. For example, the auxiliary storage device 303 is a ROM, a HDD, a flash memory, or a combination thereof. Data stored in the auxiliary storage device 303 is loaded into the memory 302 as needed. ROM is an abbreviation for Read Only Memory. HDD is an abbreviation for Hard Disk Drive.

[0022] The communication device 304 is a receiver and a transmitter. For example, the communication device 304 is a communication chip or a NIC. Communication of the satellite antenna controller 300 is performed using the communication device 304. NIC is an abbreviation for Network Interface Card.

[0023] The input / output interface 305 is a port to which an input device and an output device are connected. For example, the input / output interface 305 is a USB terminal, the input devices are a keyboard and a mouse, and the output device is a display. Input and output of the satellite antenna control device 300 is performed using the input / output interface 305. USB is an abbreviation for Universal Serial Bus.

[0024] The satellite antenna control device 300 comprises elements such as a position information acquisition unit 311, a channel allocation unit 312, a beam forming unit 313, and a control information output unit 314. These elements are realized by software.

[0025] The auxiliary storage device 303 stores a satellite antenna control program for causing a computer to function as a position information acquisition unit 311, a channel allocation unit 312, a beam forming unit 313, and a control information output unit 314. The satellite antenna control program is loaded into the memory 302 and executed by the processor 301. The auxiliary storage device 303 also stores an OS. At least a part of the OS is loaded into the memory 302 and executed by the processor 301. The processor 301 executes the satellite antenna control program while executing the OS. OS is an abbreviation for Operating System.

[0026] Input and output data for the satellite antenna control program are stored in the storage unit 320 . The auxiliary storage device 303 functions as the storage unit 320. However, a storage device such as the memory 302, a register in the processor 301, or a cache memory in the processor 301 may function as the storage unit 320 instead of or together with the auxiliary storage device 303.

[0027] The satellite antenna control program can be recorded (stored) in a computer-readable manner on a non-volatile recording medium such as an optical disk or flash memory.

[0028] ***Explanation of Operation*** The operation procedure of the satellite antenna control device 300 corresponds to a satellite antenna control method, and also corresponds to a processing procedure according to a satellite antenna control program.

[0029] An overview of a satellite antenna control method will now be described. The satellite antenna control method aims to improve the gain of array antenna 210R for a particular user 101 location and the performance of array antenna 210S for a particular user 101 location. The satellite antenna control method allows for forming an optimal composite beam for a particular user 101 .

[0030] Typically, the frequency characteristics of the electric field strength (amplitude) of an element antenna in each subchannel in the communication band are not large. The frequency characteristics of the electric field strength (amplitude) between subchannels can be considered to be approximately the same. Furthermore, the same excitation coefficient is often set for the element antennas between subchannels.

[0031] Figure 4 shows a schematic diagram of conventional beamforming. It is assumed that the element antennas in the three subchannels have no frequency characteristics and that the same excitation coefficients are assigned to the element antennas for each subchannel. The shaded area represents the composite beam for the second subchannel. Conventionally, the composite beams of each subchannel are formed so that the gain of the array antenna is approximately the same for the same position. When a composite beam is formed in this way, the gain for user Ua is Ga. User Ua is a user located near the peak of the composite beam at EOC. On the other hand, the gain for user Ub is Gb. User Ub is a user located at the edge of the EOC.

[0032] FIG. 5 is a schematic diagram of beam forming according to the first embodiment. In the first embodiment, a composite beam of the second subchannel is formed so as to improve the gain in the vicinity of a specific user Ub. As a result, the gain for the specific user Ub becomes Gb', which is higher than Gb, that is, the gain for the specific user Ub is improved.

[0033] The procedure of the satellite antenna control method will be described with reference to FIG. In step S110, the location information acquisition unit 311 selects one unselected specific user from one or more specific users. The particular user is the user 101 for which the optimum composite beam is to be provided. The number of specific users is equal to or less than the number of sub-channels included in the communication band of the channelizer 220 .

[0034] For example, a satellite operator stores specific user information in advance in storage unit 320. The specific user information indicates one or more specific users. Then, location information acquisition unit 311 refers to the specific user information and selects one unselected specific user.

[0035] In steps S120 to S140, the "specific user" refers to the specific user selected in step S110.

[0036] In step S120, the location information acquisition unit 311 acquires the location information of the specific user. The location information indicates the location of a specific user. The location indicated by the location information is a target for improving the gain of the composite beam of the array antenna 210.

[0037] The location information of the specific user is acquired by any method. For example, a satellite operator stores in advance the location information of one or more specific users in the storage unit 320. The location information acquisition unit 311 then reads out the location information of the specific users from the storage unit 320. The location information of the specific user may be predefined, may be notified from the communication device 102, or may be obtained by other methods.

[0038] In step S130, the channel allocation unit 312 selects an allocation channel for a specific user from among sub-channels included in the communication band of the channelizer 220. The allocation channel for each specific user may be determined in advance. An assigned channel is a sub-channel that is to be occupied by a specific user, that is, an assigned channel is a sub-channel that is exclusively assigned to a specific user. The number of assigned channels may be two or more for one specific user, provided that the total number of assigned channels for one or more specific users is equal to or less than the number of subchannels included in the communication band of channelizer 220.

[0039] In step S140, the beam forming unit 313 selects one or more element antennas 211 from among the element antennas 211 that make up the array antenna 210, which will form a composite beam for the assigned channel. The one or more element antennas 211 that form a composite beam of the assigned channel do not necessarily have to be all of the element antennas 211 of the array antenna 210, but may be all of the element antennas 211 of the array antenna 210.

[0040] Then, the beam forming section 313 determines the excitation coefficient to be given to each of the selected element antennas 211 based on the position information of the specific user. The excitation coefficient of each element antenna 211 is determined so that the gain for a specific user position is greater in the assigned subchannel.

[0041] In step S150, the location information acquisition unit 311 determines whether there is an unselected specific user. If there is an unselected specific user, the process proceeds to step S110. If there is no unselected specific user, the process proceeds to step S160.

[0042] In step S160, the control information output unit 314 generates information (control information) indicating the excitation coefficient of each element antenna 211 for each assigned channel. Then, the control information output unit 314 transmits the control information to the communication device 121.

[0043] The communication device 121 receives the control information and transmits the control information to the communication satellite 200. In other words, the control information is uploaded to the communication satellite 200. In the communication satellite 200, the communication device 201 receives the control information. Then, the control device 230 sets the excitation coefficient of each element antenna 211 as a parameter for each assigned channel in accordance with the control information.

[0044] The synthesized beam of the array antenna 210 will be explained below. The gain of the composite beam is calculated by combining the input and output of element antenna 211R.

[0045] gain G s(P) is expressed as follows: It is assumed that the array antenna 210R is made up of n element antennas 211R, and that n element antennas 211R are used. gain G s (P) denotes the gain of the composite beam for user position P in the s-th subchannel. The user position P is the position of a specific user and is represented by coordinate values. The coordinate values ​​may be represented by an elevation angle and an azimuth angle, a latitude and a longitude, or other numerical values.

[0046] G s (P)=20log10(|E s (P)|) E s (P)=E s1 (P)w s1 +E s2 (P)w s2 +…+E sn (P)w sn w sk =A sk exp(jΦ sk )

[0047] log10(x) represents the base 10 logarithm of a number x. E s (P) represents the electric field of the s-th subchannel in the direction from array antenna 210R to user position P. E sk (P) represents the electric field of the sth sub-channel in the direction from the kth element antenna 211R to the user position P. "k" is an integer between 1 and n. w sk represents the weighting coefficient (excitation coefficient) of the k-th element antenna 211 in the s-th subchannel. The beam of each element antenna 211R has an excitation coefficient W sk is synthesized using A sk is the excitation coefficient w sk represents the amplitude of Φ sk is the excitation coefficient wsk represents the phase of exp(x) represents the exponential function of a number x. "j" represents the imaginary unit. |E s (P)| is the electric field E s (P) represents the intensity (amplitude).

[0048] For S subchannels included in the communication band of the channelizer 220, the gain G s (P) is calculated.

[0049] The performance of the array antenna 210S is often evaluated by the radiated power (EIRP), which is expressed as the product of the antenna gain and the input signal power. EIRP is an abbreviation for Equivalent Isotropically Radiated Power.

[0050] Performance R s (P) is expressed as follows: Performance R s (P) denotes the EIRP for user position P on the s-th subchannel.

[0051] R s (P)=20log10(|E s '(P)|) E s '(P)=E s1 (P)w s1 r s1 +E s2 (P)w s2 r s2 +…+E sn (P)w sn r sn

[0052] E s '(P) is the input r from the amplifier to each element antenna 211S sk This represents the electric field when taking into account |E s '(P)| is the electric field E s '(P) represents the intensity (amplitude).

[0053] The calculation of the composite beam is based on the excitation coefficient W sk The calculation of the composite beam is performed by calculating the gain G s (P) and performance R s This is done to optimize the value of (P). sk is taken into consideration. Electric field E sk (P) is, for example, a pre-calculated value or an experimentally obtained value.

[0054] The composite beam may be calculated using any method that yields the desired gain and performance. For example, the calculation of the composite beam may be performed using an optimization method or a brute force method, or may be performed using a method that references data (experimental values, calculated values, etc.) Examples of optimization methods are minimax and particle swarm optimization.

[0055] Complementing satellite communications with a satellite antenna control method. An assigned channel is used for satellite communication of a specific user, specifically, when the satellite communication of a specific user becomes unstable.

[0056] For satellite communications of users 101 other than the specific user, the remaining subchannels, excluding the channels assigned to each specific user, from the subchannels included in the communication band of the channelizer 220, are used. If the gain is improved, the carrier power to noise ratio (C / N ratio) will increase. The following Shannon-Hartley theorem holds between the C / N ratio and the channel capacity C:

[0057] C=B LOG2(1+C / N)

[0058] "B" represents the bandwidth of the subchannel. LOG2(x) represents the logarithm of a number x in base 2.

[0059] The ratio of the communication capacity after the change to the communication capacity before the change of the synthesized beam can be considered as the frequency utilization efficiency. Therefore, an improvement in the C / N ratio means an improvement in frequency utilization efficiency, which leads to the stabilization of communications.

[0060] ***Summary of the first embodiment*** The first embodiment aims at frequency allocation and composite beamforming to provide optimal satellite communications to users within the EOC. A control station 110 installed on the ground has the functions of acquiring location information of the user 101, allocating subchannels to the user 101, and calculating composite beams for the subchannels. The control station 110 then forms an optimal beam for a specific user position. Conventional satellite-mounted antenna control does not take into account the location information of individual users, and furthermore, individual subchannel allocation and composite beamforming are not performed for individual users. In the first embodiment, a dedicated sub-channel is assigned to a user 101 in an unstable communication state, and an optimal composite beam is calculated for the user 101.

[0061] ***Effects of the First Embodiment*** In the first embodiment, a part of a band (sub-channel) that is conventionally provided to an unspecified number of users is explicitly allocated to a specific user, and a composite beam with a large gain in the direction of the specific user is formed. This increases the carrier power to noise ratio (C / N ratio). If the C / N ratio is improved, the frequency utilization efficiency will also improve, and satellite communications can be stabilized. The first embodiment is particularly effective for a particular user 101 whose satellite communication line is unstable due to weather conditions or the like.

[0062] ***Features of the First Embodiment*** The first embodiment relates to a method for controlling an array antenna and a channelizer mounted on a satellite. In the first embodiment, a part (sub-channel) of the communication band of the channelizer 220 is exclusively allocated to a specific user. In the first embodiment, excitation coefficients to be given to element antennas 211 constituting array antenna 210 are determined so that the gain at the position of a specific user in an exclusively assigned subchannel is greater than the gain achieved by a composite beam covering an unspecified number of people. Unlike conventional methods in which a communication band is used by an unspecified number of users, the first embodiment allows a specific user to occupy a sub-channel. The first embodiment increases the gain in the direction of a specific user by utilizing user location information that is not used in conventional methods. The calculation of the composite beam is performed by a control station 110 installed on the ground. The calculation results are then transmitted via a gateway station 120 to the satellite-mounted array antenna and satellite-mounted channelizer. The method of the first embodiment can be applied to both a transmitting satellite-mounted antenna and a receiving satellite-mounted antenna.

[0063] Embodiment 2 The following mainly describes the differences from the first embodiment regarding the mode of acquiring the location information of a specific user.

[0064] ***Configuration Description*** The configuration of the satellite communication system 100 is the same as that in the first embodiment. However, there is a location information database. The location information database is a database in which the location information of one or more specific users is registered. The location information database may be included in the satellite antenna control device 300, or may be included in a device separate from the satellite antenna control device 300.

[0065] ***Explanation of Operation*** The procedure of the satellite antenna control method is the same as that in embodiment 1. However, the location information of the specific user is acquired in step S120 as follows. In step S120, the location information acquisition unit 311 accesses the location information database and acquires the location information of the specific user from the location information database.

[0066] ***Effects of the Second Embodiment*** If communication is not possible due to weather conditions, it may not be possible to obtain location information of the user 101 from the communication device 102 . Therefore, in the second embodiment, a location information database (DB) is used. The location information DB stores in advance location information set when registering a radio station license or location information periodically notified to the control station 110 under circumstances such as fine weather when there are no communication problems. It is not necessary to use a satellite communication line for communication with the control station 110 under fine weather, and other communication means may be used. When it becomes necessary to improve the gain at a user's location due to bad weather or other factors, the location information DB is accessed through a function that calls the location information DB to obtain the location information of the specific user. By using this method, the location of the specific user can be accurately determined, and the optimal beam can be formed for the user's location, stabilizing satellite communications for the specific user.

[0067] Embodiment 3 A mode for forming an optimum composite beam for a specific user when the satellite communication of the specific user is unstable will be described below with reference to Figs. 7 and 8, mainly in terms of differences from the first embodiment.

[0068] ***Configuration Description*** The configuration of the satellite antenna control device 300 will be described with reference to FIG. The satellite antenna control device 300 further comprises an element called a communication state estimation unit 315 . The satellite antenna control program also causes the computer to function as a communication state estimation unit 315 .

[0069] ***Explanation of Operation*** The procedure of the satellite antenna control method will be described with reference to FIG. In step S310, the location information acquisition unit 311 selects a specific user. Step S310 is the same as step S110 in the first embodiment.

[0070] In step S320, the location information acquisition unit 311 acquires the location information of the specific user. Step S320 is the same as step S120 in the first embodiment.

[0071] In step S330, the communication state estimation unit 315 estimates the state of satellite communication at the location of the specific user based on the location information of the specific user.

[0072] The satellite communication conditions are estimated as follows: The communication state estimation unit 315 acquires observation information about the location of a specific user. The observation information includes, for example, weather information, traffic information, a communication record between the specific user and the gateway station 120, and observation results obtained using observation equipment such as a drone. The communication state estimation unit 315 estimates the degree of degradation of satellite communication based on the acquired observation information. Any estimation method may be used as long as it can quantitatively examine changes in the current communication state compared to the communication state under normal conditions (such as clear skies). For example, the communication state estimation unit 315 calculates a propagation environment formula used for link design for satellite communication to estimate the degree of degradation of satellite communication.

[0073] If it is estimated that the satellite communication conditions at the specific user's location are unstable, the process proceeds to step S340. If it is estimated that the satellite communication conditions at the specific user's location are not unstable, the process proceeds to step S360.

[0074] Steps S340 to S370 are the same as steps S130 to S160 in the first embodiment.

[0075] ***Effects of the Third Embodiment*** In the third embodiment, the communication state at the position of a specific user is estimated. If the estimation result shows that the gain of array antenna 210 at the user position is insufficient, a subchannel is allocated to the specific user and the composite beam is optimized. By estimating the communication status, it becomes possible to improve communication performance without overlooking situations where satellite communication for a specific user becomes unstable.

[0076] ***Example of Embodiment 3*** The third embodiment may be implemented in combination with the second embodiment. That is, the location information acquisition unit 311 may acquire the location information of a specific user from a location information database.

[0077] Embodiment 4 The embodiment for changing the excitation coefficient of element antenna 211S when the radiation power of array antenna 210S is lower than the desired power will be described with reference to FIGS. 9 and 10, focusing mainly on the differences from the first embodiment.

[0078] ***Configuration Description*** The configuration of the satellite antenna control device 300 will be described with reference to FIG. The satellite antenna control device 300 further comprises an element called a radiated power calculation unit 316 . The satellite antenna control program also causes the computer to function as a radiated power calculation unit 316 .

[0079] ***Explanation of Operation*** The procedure of the satellite antenna control method for array antenna 210R is the same as that in the first embodiment.

[0080] The procedure for controlling the satellite antenna for the array antenna 210S will be described with reference to FIG. Steps S410 to S430 are the same as steps S110 to S130 in the first embodiment.

[0081] In step S440, the beam forming unit 313 determines the excitation coefficients of each of one or more element antennas 211S that form a composite beam for the assigned channel, based on the location information of the specific user. Here, the beam forming section 313 takes into consideration the amplification factor of the amplifier connected to the array antenna 210S.

[0082] The excitation coefficient of each element antenna 211S is determined as follows. First, the beam forming unit 313 checks the gain of the amplifier for the assigned channel. For example, the gain specified for the communication satellite 200 is recorded in the memory unit 320, and the beam forming unit 313 checks the gain recorded in the memory unit 320. Then, the beam forming section 313 determines the excitation coefficient of each element antenna 211S based on the position information of the specific user and the amplification factor of the amplifier for the assigned channel. For example, the beam forming unit 313 determines the number of element antennas 211S that form a composite beam of the assigned channel based on the amplification factor, selects the determined number of element antennas 211S, and determines the excitation coefficient of each of the selected element antennas 211S based on the location information of a specific user.

[0083] In step S450, the radiated power calculation unit 316 calculates the radiated power of the array antenna 210S for the assigned channel based on the determined excitation coefficient.

[0084] In step S460, the beam forming unit 313 determines whether the requirement for changing the gain of the amplifier for the assigned channel is met.

[0085] If requirements (1) and (2) are met, the change requirements are met. Requirement (1) is that the calculated radiated power is smaller than the desired power, which is determined in advance. Requirement (2) is that the number of changes has not reached the upper limit. The number of changes is the number of times the amplification factor of the amplifier for the assigned channel has been changed. The initial value of the number of changes is zero, and the number of changes is incremented by one each time step S470 is executed. The upper limit is determined in advance.

[0086] If the change requirements are met, the process proceeds to step S470. If the change requirements are not met, the process proceeds to step S480.

[0087] In step S470, the beam forming unit 313 changes the amplification factor of the amplifier for the assigned channel. For example, the beam forming unit 313 increases the amplification factor by a fixed value.

[0088] After step S470, the process proceeds to step S440. Then, the beam forming section 313 re-determines the excitation coefficients taking into account the changed amplification factor. For example, the beam forming section 313 increases the number of element antennas 211S that form the composite beam in accordance with the change in the amplification factor, and determines the excitation coefficient of each element antenna 211S. Alternatively, the channel allocation unit 312 may increase the number of allocated channels, and the beam forming unit 313 may determine the excitation coefficient of the element antenna 211S for each allocated channel.

[0089] In step S480, the location information acquisition unit 311 determines whether there is an unselected specific user. If there is an unselected specific user, the process proceeds to step S410. If there is no unselected specific user, the process proceeds to step S490.

[0090] In step S490, the control information output unit 314 generates information (control information) indicating the excitation coefficient of each element antenna 211S and the amplification factor of the amplifier for each assigned channel. Then, the control information output unit 314 transmits the control information to the communication device 121.

[0091] The communication device 121 receives the control information and transmits the control information to the communication satellite 200. In other words, the control information is uploaded to the communication satellite 200. In the communication satellite 200, the communication device 201 receives the control information. Then, the control device 230 sets the excitation coefficient of each element antenna 211 and the amplification factor of the amplifier as parameters for each assigned channel in accordance with the control information.

[0092] ***Effects of the Fourth Embodiment*** Even if the beam is optimized for a specific user, further improvement of the EIRP of the satellite-mounted transmitting antenna may be required depending on the communication conditions. Therefore, in the fourth embodiment, the output (amplification factor) of the amplifier connected to the transmitting antenna, that is, the input value to the transmitting antenna, is adjusted. If the desired gain cannot be achieved even when the amplification factor is increased, the number of elements involved in the composite beam is increased, or the number of subchannels assigned to a specific user is increased. This provides more power to certain users who require further improvement in EIRP. The fourth embodiment is particularly applicable to a transmitting antenna.

[0093] ***Example of Embodiment 4*** The fourth embodiment may be implemented in combination with the second embodiment. That is, the location information acquisition unit 311 may acquire the location information of a specific user from a location information database. The fourth embodiment may be implemented in combination with the third embodiment. That is, the satellite antenna control device 300 may include a communication state estimation unit 315 to form an optimal composite beam for a specific user when the satellite communication of the specific user is unstable.

[0094] Embodiment 5. The embodiment for changing the amplification factor for each assigned channel so that the total amplification amount of the amplifiers does not exceed the limit amount will be described with reference to FIG. 11, mainly in terms of the differences from the fourth embodiment.

[0095] ***Configuration Description*** The configuration of the satellite communication system 100 is the same as that in the first embodiment.

[0096] ***Explanation of Operation*** The procedure of the satellite antenna control method for array antenna 210R is the same as that in the first embodiment.

[0097] The procedure for controlling the satellite antenna for the array antenna 210S will be described with reference to FIG. In step S510, the location information acquisition unit 311 acquires the location information of each specific user. Step S510 corresponds to step S420 in the fourth embodiment.

[0098] Specifically, the location information acquisition unit 311 executes step S420 for each specific user in parallel to acquire multiple pieces of location information for multiple specific users.

[0099] In step S520, the channel allocation unit 312 selects an allocation channel for each specific user. Step S520 corresponds to step S430 in the fourth embodiment.

[0100] Specifically, the channel allocation unit 312 executes step S430 for each specific user in parallel to select a plurality of allocation channels for the plurality of specific users.

[0101] In step S530, the beam forming unit 313 determines the excitation coefficients of the element antennas 211S for the assigned channels for each specific user, taking into consideration the amplification factor of the amplifier for the assigned channel. Step S530 corresponds to step S440 in the fourth embodiment.

[0102] Specifically, the beam forming unit 313 executes step S440 for each assigned channel in parallel to determine multiple sets of excitation coefficients for multiple assigned channels.

[0103] In step S540, the radiated power calculation unit 316 calculates the radiated power of the array antenna 210S for the assigned channel for each specific user based on the excitation coefficient of each element antenna 211S for the assigned channel. Step S540 corresponds to step S450 in the fourth embodiment.

[0104] Specifically, the beam forming unit 313 executes step S450 for each assigned channel in parallel to calculate a plurality of radiated powers for a plurality of assigned channels.

[0105] In step S550, the beam forming unit 313 determines whether the requirement for changing the gain of the amplifier is met. Step S550 corresponds to step S460 in the fourth embodiment.

[0106] Specifically, the beam forming unit 313 executes step S460 for each assigned channel in parallel, and determines whether the change requirement of step S460 is met for each assigned channel. If the change requirement in step S460 is met in at least any of the assigned channels, the requirement for changing the gain of the amplifier is met.

[0107] If the requirement for changing the gain of the amplifier is met, the process proceeds to step S560. If the requirement for changing the gain of the amplifier is not met, the process proceeds to step S570.

[0108] In step S560, the beam forming unit 313 changes the amplification factor of the amplifier for at least one of the assigned channels so that the total amplification amount of the amplifiers does not exceed the limit amount. The total gain of the amplifier is calculated based on the gain for each assigned channel and the gain for the remaining sub-channels, which are predetermined. The limit amount is the upper limit of the amplification amount of the amplifier and is determined in advance.

[0109] For example, the beam forming unit 313 decreases the amplification factor for an assigned channel corresponding to a radiation power greater than the desired power, and increases the amplification factor for an assigned channel corresponding to a radiation power less than the desired power.

[0110] After step S560, the process proceeds to step S530. Then, the beam forming unit 313 re-determines the excitation coefficient for each assigned channel, taking into account the changed amplification factor. Step S530 after step S560 corresponds to step S440 after step S470 in the fourth embodiment.

[0111] Step S570 is the same as step S490 in the fourth embodiment.

[0112] ***Effects of the Fifth Embodiment*** In the fifth embodiment, the processes of the fourth embodiment are executed in parallel. There is a limit to the amount of amplification that can be achieved by an amplifier connected to a transmitting antenna, and increasing the output of one amplifier may result in the total amount of amplification exceeding this limit. In the fifth embodiment, the power allocation is changed in consideration of the balance of all subchannels, and the amplification factor of each subchannel is set so that the total amplification amount does not exceed the limit. Specifically, the allocation to subchannels with a power margin is reduced, and the allocation to subchannels with a power margin is increased. This allows the maximum EIRP, taking into account the amplifier performance, to be achieved for all subchannels assigned to the satellite's transmitting antenna, improving communication conditions.

[0113] ***Example of Embodiment 5*** Like the fourth embodiment, the fifth embodiment may be implemented in combination with the second and third embodiments.

[0114] Embodiment 6 The following describes the mode of allocating subchannels to each specific user in consideration of the location of each specific user, mainly in terms of differences from the first embodiment, with reference to FIG.

[0115] ***Configuration Description*** The configuration of the satellite communication system 100 is the same as that in the first embodiment.

[0116] ***Explanation of Operation*** The procedure of the satellite antenna control method will be described with reference to FIG. In step S610, the location information acquisition unit 311 acquires the location information of each specific user. Step S610 corresponds to step S120 in the first embodiment.

[0117] Specifically, the location information acquisition unit 311 executes step S120 for each specific user in parallel to acquire multiple pieces of location information for multiple specific users.

[0118] In step S620, the channel allocation unit 312 selects an allocation channel for each specific user based on the location information of the specific users.

[0119] For example, the channel allocation unit 312 selects a sub-channel with a lower frequency as the distance between a specific user and the communication satellite 200 increases, and selects a sub-channel with a higher frequency as the distance between the specific user and the communication satellite 200 decreases.

[0120] In step S630, the beam forming unit 313 determines, for each assigned channel, the excitation coefficients of each of the one or more element antennas 211S for the assigned channel. Step S640 corresponds to step S140 in the first embodiment.

[0121] Specifically, the beam forming unit 313 executes step S140 for each assigned channel in parallel to determine multiple sets of excitation coefficients for multiple assigned channels.

[0122] Step S640 is the same as step S160 in the first embodiment.

[0123] ***Effects of the Sixth Embodiment*** In the sixth embodiment, sub-channels to be allocated can be set while being interchanged between users. In free space, the radio wave propagation loss of power is generally inversely proportional to the square of the distance between the transmitter and receiver. Also, the radio wave propagation loss of power increases in proportion to the square of the frequency. Therefore, the radio wave propagation loss decreases when a lower frequency subchannel is assigned to a user that is farther away. This reduces radio wave propagation loss for users who are farther away from the satellite than other users, improving communication conditions.

[0124] ***Example of the sixth embodiment*** The sixth embodiment may be implemented in combination with the second embodiment. That is, the location information acquisition unit 311 may acquire the location information of a specific user from the location information database. The sixth embodiment may be implemented in combination with the third embodiment. That is, the satellite antenna control device 300 may include a communication state estimation unit 315, and may form an optimal composite beam for a specific user when the satellite communication of the specific user is unstable. The sixth embodiment may be implemented in combination with the fourth embodiment. That is, the satellite antenna control device 300 may include a radiation power calculation unit 316, and may change the excitation coefficient of the element antenna 211S when the radiation power of the array antenna 210S is smaller than the desired power. The sixth embodiment may be implemented in combination with the fifth embodiment. That is, the satellite antenna control device 300 may change the amplification factor for each assigned channel so that the total amplification amount of the amplifiers does not exceed the limit amount.

[0125] ***Supplementary explanation of implementation form*** Each embodiment is an example of a preferred embodiment and is not intended to limit the technical scope of the present disclosure. Each embodiment may be implemented in part or in combination with other embodiments. Procedures described using flowcharts, etc. may be modified as appropriate.

[0126] Each element of the satellite antenna controller 300 may be implemented in software, hardware, firmware, or a combination thereof. The "unit" of each element of the satellite antenna control device 300 may be read as a "process," a "step," a "circuit," or a "circuitry."

[0127] Various aspects of the present disclosure are described below as appendices. (Appendix 1) a channel allocation unit that selects a subchannel to be occupied by a user as an allocation channel from among subchannels included in a communication band of a channelizer mounted on the communication satellite; a beam forming unit that determines, based on the user's position information, excitation coefficients to be applied to one or more element antennas that form a composite beam of the assigned channel among element antennas that constitute an array antenna mounted on the communication satellite; A satellite antenna control device comprising:

[0128] (Appendix 2) A location information acquisition unit acquires location information of one or more users from a database in which the location information of the users is registered. 2. A satellite antenna control device as defined in claim 1.

[0129] (Appendix 3) the satellite antenna control device includes a communication state estimation unit that estimates a state of satellite communication at the user's location based on the user's location information, the channel allocation unit selects the allocated channel when the state of the satellite communication is estimated to be unstable; The beam forming unit determines the excitation coefficients when the state of the satellite communication is estimated to be the unstable state. 3. A satellite antenna control device according to claim 1 or 2.

[0130] (Appendix 4) the array antenna is a transmitting array antenna to which an amplifier is connected, the satellite antenna control device includes a radiation power calculation unit, the beam forming unit determines the excitation coefficients in consideration of the amplification factor of the amplifier for the assigned channel; the radiated power calculation unit calculates a radiated power of the array antenna for the assigned channel based on the determined excitation coefficient; The beam forming unit changes the amplification factor and re-determines the excitation coefficient when the calculated radiation power is smaller than a desired power. 4. A satellite antenna control device according to any one of claims 1 to 3.

[0131] (Appendix 5) the channel allocation unit selects an allocation channel for each of a plurality of users; the beam forming unit determines the excitation coefficient for the assigned channel for each user in consideration of the amplification factor for the assigned channel of the amplifier; the radiated power calculation unit calculates the radiated power for the assigned channel based on the excitation coefficient for the assigned channel for each of the users; When the radiation power for at least any of the assigned channels is smaller than the desired power, the beam forming unit changes the amplification factor for at least any of the assigned channels so that the total amplification amount of the amplifiers does not exceed a limit amount, and re-determines the excitation coefficient for the assigned channel for each of the users. 5. A satellite antenna control device as described in appendix 4.

[0132] (Appendix 6) The channel allocation unit selects, as the allocation channel for each of the plurality of users, a sub-channel with a lower frequency as the distance from the communication satellite increases, based on a plurality of pieces of location information for the plurality of users. 6. A satellite antenna control device according to any one of claims 1 to 5.

[0133] (Appendix 7) 7. A control station having a satellite antenna control device according to any one of claims 1 to 6.

[0134] (Appendix 8) selecting a subchannel to be occupied by the user as an assigned channel from among subchannels included in a communication band of a channelizer mounted on the communication satellite; determining, based on the user's position information, excitation coefficients to be applied to one or more element antennas that form a composite beam of the assigned channel among element antennas that constitute an array antenna mounted on the communication satellite; A method for controlling a satellite antenna. [Explanation of symbols]

[0135] 100 Satellite communication system, 101 User, 102 Communication device, 110 Control station, 120 Gateway station, 121 Communication device, 200 Communication satellite, 201 Communication device, 210 Array antenna, 211 Element antenna, 220 Channelizer, 230 Control device, 300 Satellite antenna control device, 301 Processor, 302 Memory, 303 Auxiliary storage device, 304 Communication device, 305 Input / output interface, 311 Position information acquisition unit, 312 Channel allocation unit, 313 Beam forming unit, 314 Control information output unit, 315 Communication state estimation unit, 316 Radiated power calculation unit, 320 Memory unit.

Claims

1. A location information acquisition unit that acquires user location information from a database in which location information of one or more users is registered; a communication state estimation unit that estimates a state of satellite communication at the user's location based on the user's location information; a channel allocation unit that, when it is estimated that the state of the satellite communication is unstable, selects, as an allocation channel, a sub-channel to be occupied by the user from among sub-channels included in a communication band of a channelizer mounted on the communication satellite; a beam forming unit that, when it is estimated that the state of the satellite communication is the unstable state, determines, based on the position information of the user, excitation coefficients to be applied to one or more element antennas that form a composite beam of the assigned channel among element antennas that constitute an array antenna mounted on the communication satellite; A satellite antenna control device comprising:

2. A location information acquisition unit that acquires user location information from a database in which location information of one or more users is registered; a channel allocation unit that selects, as an allocation channel, a subchannel to be occupied by the user from among subchannels included in a communication band of a channelizer mounted on the communication satellite; a beam forming unit that determines excitation coefficients to be applied to one or more element antennas that form a composite beam of the assigned channel among element antennas that are mounted on the communication satellite and to which amplifiers are connected, based on the position information of the user, taking into account the amplification factor of the amplifier for the assigned channel; a radiation power calculation unit that calculates a radiation power of the array antenna for the assigned channel based on the determined excitation coefficient, The beam forming unit changes the amplification factor and re-determines the excitation coefficient when the calculated radiation power is smaller than a desired power. Satellite antenna control device.

3. the channel allocation unit selects an allocation channel for each of a plurality of users; the beam forming unit determines the excitation coefficient for the assigned channel for each user in consideration of the amplification factor for the assigned channel of the amplifier; the radiated power calculation unit calculates the radiated power for the assigned channel based on the excitation coefficient for the assigned channel for each of the users; When the radiation power for at least any of the assigned channels is smaller than the desired power, the beam forming unit changes the amplification factor for at least any of the assigned channels so that the total amplification amount of the amplifiers does not exceed a limit amount, and re-determines the excitation coefficient for the assigned channel for each of the users.

3. The satellite antenna control device according to claim 2.

4. A location information acquisition unit that acquires location information of each of a plurality of users from a database in which location information of each of the plurality of users is registered; a channel allocation unit that selects, for each of the plurality of users, a sub-channel to be occupied by the user from among sub-channels included in a communication band of a channelizer mounted on the communication satellite, as an allocation channel; a beam forming unit that determines, for each of the plurality of users, excitation coefficients to be applied to one or more element antennas that form a composite beam of the assigned channel among element antennas that constitute an array antenna mounted on the communications satellite, based on the position information of the user; The channel allocation unit selects, as the allocation channel for each of the plurality of users, a sub-channel with a lower frequency as the distance from the communication satellite increases for each of the plurality of users based on the location information of each of the plurality of users. Satellite antenna control device.

5. A control station having the satellite antenna control device according to any one of claims 1 to 4.

6. A satellite antenna control device comprising: Acquire location information of the user from a database in which location information of each of one or more users is registered; Estimating a satellite communication state at the user's location based on the location information of the user; When it is estimated that the state of the satellite communication is unstable, a sub-channel to be occupied by the user is selected as an allocation channel from among sub-channels included in a communication band of a channelizer mounted on the communication satellite; When it is estimated that the state of the satellite communication is unstable, an excitation coefficient to be applied to each of one or more element antennas that form a composite beam of the assigned channel among element antennas that constitute an array antenna mounted on the communication satellite is determined based on the position information of the user. A method for controlling a satellite antenna.

7. A satellite antenna control device comprising: Acquire location information of the user from a database in which location information of each of one or more users is registered; selecting a subchannel to be occupied by the user as an assigned channel from among subchannels included in a communication band of a channelizer mounted on the communication satellite; determining an excitation coefficient to be applied to each of one or more element antennas that form a composite beam of the assigned channel among element antennas that constitute a transmitting array antenna that is mounted on the communications satellite and to which an amplifier is connected, based on the location information of the user, taking into account an amplification factor of the amplifier for the assigned channel; calculating a radiation power of the array antenna for the assigned channel based on the determined excitation coefficient; If the calculated radiation power is smaller than the desired power, the amplification factor is changed and the excitation coefficient is determined again. A method for controlling a satellite antenna.

8. A satellite antenna control device comprising: acquiring location information of each of the plurality of users from a database in which location information of each of the plurality of users is registered; selecting, for each of the plurality of users, a subchannel to be occupied by the user from among subchannels included in a communication band of a channelizer mounted on the communication satellite, as an assigned channel; For each of the plurality of users, an excitation coefficient to be applied to one or more element antennas that form a composite beam of the assigned channel among element antennas that constitute an array antenna mounted on the communications satellite is determined based on the position information of the user.

1. A satellite antenna control method, comprising: The satellite antenna control device selects, as the assigned channel for each of the plurality of users, a sub-channel having a lower frequency as the distance from the communication satellite increases for each of the plurality of users based on the position information of each of the plurality of users. A method for controlling a satellite antenna.

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