Satellite communications system, repeater control station, satellite repeater, and transmission power determination method

Abstract

To provide a satellite communication system configured to improve utilization efficiency of power resources in a transponder.SOLUTION: A satellite communication system includes: a transponder having a plurality of transmission elements and a power amplifier which amplifies transmission power, and configured to output transmission signals from the transmission elements to form a plurality of transmission beams; and a transponder control station 5 which controls the transponder. The transponder control station 5 includes a power adjustment coefficient calculation unit 77 which determines a transmission power allocation ratio which is a ratio of transmission power allocated to each of the transmission elements with respect to target power which is output power obtained when linearity of output power of the power amplifier with respect to input power to the power amplifier is maintained, and calculates a transmission power adjustment coefficient on the basis of the maximum value of the transmission power allocation ratio determined for each of the transmission elements. The transponder includes a transmission power adjustment unit which adjusts transmission power of each of the transmission elements on the basis of the transmission power adjustment coefficient.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present disclosure relates to a satellite communication system that performs communication via a satellite repeater, a repeater control station, a satellite repeater, and a transmission power determination method. [Background technology]

[0002] A satellite communication system is required to be flexibly adaptable to fluctuations in communication traffic between ground stations via a satellite repeater. In a conventional satellite communication system, as disclosed in Patent Document 1, a high-output power amplifier capable of withstanding an increase in transmission power accompanying an increase in communication traffic is arranged in the satellite repeater, and power is allocated to each of a plurality of transmission beams formed by the satellite repeater. Hereinafter, the high-output power amplifier is referred to as a power amplifier. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-94729 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional satellite communication systems, it has been difficult to optimize the distribution of transmission power of a satellite repeater that changes according to operational requirements using functions such as frequency flexibility or area flexibility required for recent high-throughput satellites, that is, a function for changing the frequency bandwidth of a beam, or a function for dynamically changing the irradiation direction of a beam, the coverage area of ​​a beam, or the gain of a beam, such as digital beam forming (DBF). For example, in a satellite repeater, the gain of the repeater is determined so that the power amplifier is not saturated even when a signal with the maximum expected reception power is relayed and the power is amplified by a power amplifier, such as in a case where a signal received by multiple reception beams is transmitted by one transmission beam. When such a satellite repeater is used, the performance of the power amplifier is not fully utilized when the number of beams used as an operational requirement is small or when the actual communication traffic is small. According to the conventional technology, there is a problem that the performance of the power amplifier is not fully utilized, resulting in low utilization efficiency of power resources in the satellite repeater.

[0005] The present disclosure has been made in consideration of the above, and has an object to provide a satellite communications system that can improve the utilization efficiency of power resources in a satellite repeater. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the object, the satellite communication system according to the present disclosure includes a satellite repeater having a plurality of transmitting elements and a power amplifier for amplifying the transmission power supplied to each of the plurality of transmitting elements, and forming a plurality of transmission beams by outputting a transmission signal from each of the plurality of transmitting elements, and a repeater control station for controlling the satellite repeater. The repeater control station has a power adjustment coefficient calculation unit for calculating a transmission power allocation rate, which is a ratio of the transmission power allocated to each of the plurality of transmitting elements to a target power, which is the output power when the linearity of the output power of the power amplifier with respect to the input power to the power amplifier is maintained, and for calculating a transmission power adjustment coefficient based on the maximum value of the transmission power allocation rates calculated for each of the plurality of transmitting elements. The satellite repeater has a transmission power adjustment unit for adjusting the transmission power of each of the plurality of transmitting elements based on the transmission power adjustment coefficient. Effect of the Invention

[0007] The satellite communication system according to the present disclosure advantageously improves the efficiency of power resource utilization in a satellite repeater. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram of beam irradiation by a satellite communication system according to a first embodiment; [Diagram 2] FIG. 1 is a diagram showing a configuration example of a satellite communication system according to a first embodiment; [Diagram 3] FIG. 1 is a diagram showing a configuration example of a satellite repeater included in a satellite communication system according to a first embodiment; [Figure 4] FIG. 4 shows an example of the configuration of a DCH / DBF included in the satellite repeater shown in FIG. 3. [Diagram 5] FIG. 5 shows an example of the configuration of a transmission DBF unit included in the DCH / DBF shown in FIG. [Figure 6] FIG. 1 is an explanatory diagram of a power contribution rate due to an excitation coefficient, which is related to the determination of a transmission power adjustment coefficient in the first embodiment; [Figure 7] FIG. 1 is an explanatory diagram of a band allocation rate of a transmission beam related to the determination of a transmission power adjustment coefficient in the first embodiment; [Figure 8] FIG. 1 is an explanatory diagram of a transmission power allocation rate related to the determination of a transmission power adjustment coefficient in the first embodiment. [Figure 9] FIG. 1 shows an example of a correspondence relationship between a transmission beam and a transmission element, and a transmission power allocation ratio of each transmission element in the first embodiment. [Figure 10] FIG. 1 is a diagram showing a configuration example of a repeater control station included in a satellite communication system according to a first embodiment; [Figure 11] 1 is a flowchart showing a processing procedure of the satellite communication system according to the first embodiment. [Figure 12] FIG. 1 shows an example of the configuration of a control circuit according to a first embodiment. [Figure 13] FIG. 1 shows an example of the configuration of a processing circuit according to a first embodiment. [Figure 14] FIG. 13 is a diagram showing a configuration example of a satellite repeater included in a satellite communication system according to a second embodiment; [Figure 15] FIG. 15 shows an example of the configuration of a DCH / DBF included in the satellite repeater shown in FIG. 14. [Figure 16] FIG. 13 is a diagram showing an example of a correspondence relationship between a transmission beam and a transmission element, and a transmission power allocation ratio of each transmission element in the third embodiment. [Figure 17] FIG. 13 is a diagram showing a configuration example of a transmission DBF unit included in a satellite repeater of a satellite communication system according to a third embodiment; [Figure 18] FIG. 13 is a diagram showing an example of a correspondence relationship between a transmission beam and a transmission element, and a power utilization rate of each transmission element in the fourth embodiment. [Figure 19] FIG. 13 is a diagram showing a configuration example of a satellite repeater included in a satellite communication system according to a fourth embodiment; [Figure 20] 11 is a flowchart showing a processing procedure of the satellite communication system according to the fourth embodiment. [Figure 21] FIG. 13 is a diagram showing a configuration example of a satellite repeater included in a satellite communication system according to a fifth embodiment; [Figure 22] FIG. 13 is a diagram showing a configuration example of a transmission DBF unit included in a satellite repeater of a satellite communication system according to a sixth embodiment; [Figure 23] FIG. 23 shows an example of a correspondence relationship between a transmission beam and a transmission element, and a transmission power allocation ratio of each transmission element in the seventh embodiment. [Figure 24] FIG. 13 is a diagram showing a configuration example of a transmission DBF unit included in a satellite repeater of a satellite communication system according to a seventh embodiment; [Diagram 25] FIG. 13 is an explanatory diagram of the operation of a satellite repeater in the satellite communication system according to the eighth embodiment. [Figure 26] FIG. 13 is a diagram showing an example of the configuration of a DCH / DBF included in a satellite repeater of a satellite communication system according to an eighth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A satellite communication system, a repeater control station, a satellite repeater, and a transmission power determination method according to the embodiments will be described in detail below with reference to the drawings. In the satellite communication system of the present disclosure, the satellite repeater forms a reception beam and a transmission beam by a DBF function capable of changing the beam irradiation direction or beam shape, and a mobile station and a fixed station, which are ground stations, communicate through the satellite repeater. In the present disclosure, in a satellite communication system in which the frequency, irradiation direction, or shape of a beam is changed according to the situation by using the frequency flexibility function and the area flexibility function of the satellite repeater, the performance of the power amplifier of the satellite repeater is not fully utilized in a situation in which the number of beams used is temporarily reduced or the actual communication traffic is reduced.

[0010] Embodiment 1 FIG. 1 is an explanatory diagram of beam irradiation by a satellite communication system according to the first embodiment. Here, irradiation of a transmission beam by a satellite communication system will be mainly described. In the case of transmission beam irradiation, an element arrangement 1 shown by a dashed circle in FIG. 1 indicates the irradiation direction of each transmitting antenna element mounted on a satellite repeater. Hereinafter, the transmitting antenna element is referred to as a transmitting element. In addition, in the case of reception beam irradiation, the element arrangement 1 indicates the irradiation direction of each receiving antenna element mounted on a satellite repeater. Hereinafter, the receiving antenna element is referred to as a receiving element. In FIG. 1, for convenience, each element arrangement 1 is represented by a circular area that is in contact with each other, but the actual irradiation range of each element used for DBF, that is, each transmitting element and each receiving element, is a circular area that overlaps each other. In other words, the actual irradiation range of each element is an area wider than each element arrangement 1.

[0011] Each of the multiple beams, beams 2-a, 2-b, 2-c, and 2-d, is an example of a transmission beam formed by DBF using a transmission element. In general, when performing two-way communication, a transmission beam and a reception beam are often formed in the same area. In the first embodiment, the formation of a transmission beam is described, but it is assumed that the reception beam is also formed in the same area as the transmission beam. Each of beams 2-a to 2-d can be said to be an example of a reception beam formed by DBF using a reception element.

[0012] An element arrangement 1-k, which is one of the multiple element arrangements 1, indicates the irradiation direction of a transmission element commonly used to form each of the beams 2-a to 2-d. That is, in the example shown in FIG. 1, the transmission element corresponding to the element arrangement 1-k is given different excitation coefficients, that is, amplitude and phase, for the mutually different transmission signals for each of the beams 2-a to 2-d. A signal in which the transmission signal corresponding to each of the beams 2-a to 2-d is superimposed is transmitted from the transmission element corresponding to the element arrangement 1-k. For the other transmission elements that contribute to the formation of each of the multiple transmission beams, appropriate excitation coefficients are given to the transmission signal corresponding to the transmission beam, so that each of the multiple transmission beams is formed. In the example shown in FIG. 1, a high-output power amplifier capable of covering the transmission power of four transmission beams is used for the transmission element corresponding to one element arrangement 1-k. Hereinafter, a configuration and a method for optimizing the transmission power will be described.

[0013] FIG. 2 is a diagram showing a configuration example of the satellite communication system 3 according to the first embodiment. FIG. 2 shows a satellite repeater 4, a repeater control station 5, and a satellite communication system control station 6 which constitute the satellite communication system 3. The satellite repeater 4 is mounted on a satellite. In the example shown in FIG. 2, the repeater control station 5 and the satellite communication system control station 6 are separate ground stations. The functions of the repeater control station 5 and the satellite communication system control station 6 may be arranged in one ground station. In other words, one ground station may serve as both the repeater control station 5 and the satellite communication system control station 6.

[0014] The satellite communication system control station 6 controls the satellite communication system 3 on the ground. The satellite communication system control station 6 decides how to operate the satellite communication system 3. The satellite communication system control station 6 decides the beam irradiation direction, beam irradiation range, beam frequency bandwidth, etc. in the satellite communication system 3. The satellite communication system control station 6 transmits a beam forming request, which is a request for forming the determined beam, to the repeater control station 5. The beam forming request includes, for example, information indicating the gain of the beam at an arbitrarily specified point on the ground. The point is represented by coordinates. The beam irradiation direction and irradiation range are expressed by the gain indicated in the beam forming request.

[0015] The repeater control station 5 controls the satellite repeater 4 on the ground and monitors the satellite repeater 4. The repeater control station 5 determines an excitation coefficient to be given to a transmission signal from the satellite repeater 4 to form a beam in accordance with a beam forming request. The repeater control station 5 transmits a telecommand, which is an instruction to control the satellite repeater 4, to the satellite repeater 4. Hereinafter, the telecommand is referred to as a control command. The repeater control station 5 sets various parameters required for the operation of the satellite repeater 4 in the satellite repeater 4 by transmitting the control command to the satellite repeater 4 using a control wireless line, and controls the satellite repeater 4. The determined excitation coefficient is set in the satellite repeater 4 by the control command. The repeater control station 5 also monitors the satellite repeater 4 by receiving information indicating the state of the satellite repeater 4 and the values ​​of various parameters by telemetry.

[0016] The satellite repeater 4 forms a plurality of transmission beams by outputting a transmission signal from each of a plurality of transmitting elements. The satellite repeater 4 forms a plurality of transmission beams, 7-1, 7-2, ..., 7-m, using a set excitation coefficient, and transmits signals through the transmission beams 7-1 to 7-m. FIG. 2 shows m transmission beams 7-1 to 7-m, where m represents the number of transmission beams. Note that the formation of reception beams is also performed in the satellite repeater 4. The satellite repeater 4 relays communications in the satellite communication system 3 by transmitting signals received through reception beams through transmission beams. Note that FIG. 2 does not show user earth stations and feeder link earth stations that transmit and receive communication signals of users who use the satellite communication system 3.

[0017] Next, the configuration of the satellite repeater 4 will be described. Fig. 3 is a diagram showing an example of the configuration of the satellite repeater 4 included in the satellite communication system 3 according to the first embodiment. The satellite repeater 4 includes receiving elements 10-1, 10-2, ..., 10-nr, low noise amplifiers (LNA: Low Noise Amplifiers) 11-1, 11-2, ..., 11-nr, down converters (DCON: Down CONverters) 12-1, 12-2, ..., 12-nr, digital channelizer / digital beam forming processing units (hereinafter referred to as DCH / DBF) 13, up converters (UCON: Up CONverters) 14-1, 14-2, ..., 14-ns, traveling wave tube amplifiers (TWTA: Traveling Wave Tube Amplifiers) 15-1, 15-2, ..., 15-ns, and transmitting elements 16-1, 16-2, ..., 16-ns. The satellite repeater 4 also includes a telecommunication control unit 17, a control antenna 18, an RF (Radio Frequency) transmitting / receiving unit 19, and a modem 20.

[0018] Fig. 3 shows nr receiving elements 10-1 to 10-nr, where nr represents the number of receiving elements. Fig. 3 also shows nr LNAs 11-1 to 11-nr and nr DCONs 12-1 to 12-nr. That is, the satellite repeater 4 includes LNAs 11-1 to 11-nr and DCONs 12-1 to 12-nr, which are processing circuits in a number corresponding to the receiving elements 10-1 to 10-nr.

[0019] Fig. 3 shows ns transmitting elements 16-1 to 16-ns, where ns represents the number of transmitting elements. Fig. 3 also shows ns UCONs 14-1 to 14-ns and ns TWTAs 15-1 to 15-ns. That is, the satellite repeater 4 includes UCONs 14-1 to 14-ns and TWTAs 15-1 to 15-ns, which are processing circuits in a number corresponding to the transmitting elements 16-1 to 16-ns. Note that nr and ns may be different numbers or the same number.

[0020] The receiving elements 10-1 to 10-nr receive signals from earth stations. The LNAs 11-1 to 11-nr amplify the received signals. The DCONs 12-1 to 12-nr convert the received signals to signals with a lower frequency than the received signals, thereby changing the frequency of the received signals to a frequency that is easy to handle in the digital signal processing at the subsequent stage. The DCH / DBF 13 sets parameters for determining the transmission power. The DCH / DBF 13 will be described in detail later.

[0021] The UCONs 14-1 to 14-ns convert the signals output from the DCH / DBF 13 into signals having a higher frequency than the signals themselves, thereby converting the signals into signals having an actual transmission frequency. Each of the TWTAs 15-1 to 15-ns is a power amplifier. The TWTAs 15-1 to 15-ns amplify the signals from the UCONs 14-1 to 14-ns, thereby amplifying the transmission power supplied to each of the multiple transmitting elements 16-1 to 16-ns. The transmitting elements 16-1 to 16-ns transmit signals to the earth station.

[0022] Depending on the output of the transmission signal, a solid-state power amplifier (SSPA) may be used together with the TWTAs 15-1 to 15-ns as a means for amplifying the signal. The receiving elements 10-1 to 10-nr and the transmitting elements 16-1 to 16-ns may have a large aperture diameter by using a reflector in order to increase the gain of the transmission and reception signals.

[0023] In the configuration shown in Fig. 3, DCONs 12-1 to 12-nr and UCONs 14-1 to 14-ns are used, but the satellite repeater 4 may be configured to apply a direct sampling technique that directly samples the frequency band of radio waves without using these. The satellite repeater 4 requires a filter or the like that cuts out signals of unnecessary frequency bands from signals transmitted to and received from the earth station. In Fig. 3, the filter or the like is not shown.

[0024] The tele-frame control unit 17 controls or sets parameters of each device in the satellite repeater 4 according to control commands from the repeater control station 5 shown in Fig. 2. The tele-frame control unit 17 also has a function of transmitting monitoring information such as the status of each device in the satellite repeater 4 and the values ​​of various parameters to the repeater control station 5 by telemetry.

[0025] The control antenna 18 receives control commands and transmits telemetry signals. The RF transceiver 19 amplifies signals and converts their frequencies. The modem 20 modulates, demodulates, encodes, and decodes signals. Signals are transmitted between the telecommunication control unit 17 and the repeater control station 5 via the control antenna 18, the RF transceiver 19, and the modem 20.

[0026] Next, the configuration of the DCH / DBF 13 will be described. Fig. 4 is a diagram showing an example of the configuration of the DCH / DBF 13 included in the satellite repeater 4 shown in Fig. 3. The DCH / DBF 13 includes AD (Analog-to-Digital) converters 30-1, 30-2, ..., 30-nr, a receiving DBF unit 40, a switch circuit 50, a transmitting DBF unit 60, and DA (Digital-to-Analog) converters 31-1, 31-2, ..., 31-ns. The receiving signals 21-1, 21-2, ..., 21-nr are signals received by the receiving elements 10-1 to 10-nr shown in Fig. 3. The transmitting signals 22-1, 22-2, ..., 22-ns are signals transmitted from the transmitting elements 16-1 to 16-ns shown in Fig. 3.

[0027] The AD converters 30-1 to 30-nr are input with the reception signals 21-1, 21-2, ..., 21-nr that have been processed by the LNAs 11-1 to 11-nr and the DCONs 12-1 to 12-nr. The AD converters 30-1 to 30-nr convert the reception signals 21-1, 21-2, ..., 21-nr, which are analog signals, into digital signals. The reception DBF unit 40 splits, that is, demultiplexes, each digital signal from the AD converters 30-1 to 30-nr into a plurality of signals of different frequency bands. The reception DBF unit 40 multiplies each signal obtained by demultiplexing by an excitation coefficient of the reception DBF. The reception DBF unit 40 obtains a signal for each demultiplexing unit of the reception beam by combining signals from a plurality of reception elements that have been processed up to the multiplication of the excitation coefficient in the DCH / DBF 13.

[0028] The switch circuit 50 switches the signal of each branch of the receiving beam to an arbitrary transmitting beam. The transmitting DBF unit 60 distributes the signal to each transmitting element, and multiplies each distributed signal by the excitation coefficient of the transmitting DBF. The transmitting DBF unit 60 also combines, i.e., multiplexes, the signals divided for each frequency band according to the frequency band of the transmitting beam, and adds the signals of each transmitting beam for each transmitting element. The DA converters 31-1 to 31-ns convert the signal from the transmitting DBF unit 60 into an analog signal. The DCH / DBF 13 outputs the transmitting signals 22-1, 22-2, ..., 22-ns, which are analog signals.

[0029] By switching the frequency bands of the reception signals 21-1 to 21-nr in a narrow band in the switch circuit 50, signals of any bandwidth can be relayed between the input and output beams, thereby realizing frequency flexibility. Furthermore, by multiplying the signals input from the reception elements 10-1 to 10-nr by an excitation coefficient and synthesizing them, or distributing the signals to be output to the transmission elements 16-1 to 16-ns and multiplying them by an excitation coefficient, area flexibility between the reception beam and the transmission beam is realized. Note that the transmission of signals in the reception DBF unit 40, the switch circuit 50, and the transmission DBF unit 60 is performed by serially converting the signals of the parallel reception beams and the signals of the parallel transmission beams in a time-division manner.

[0030] Next, the details of the transmission DBF unit 60 will be described. Fig. 5 is a diagram showing an example of the configuration of the transmission DBF unit 60 included in the DCH / DBF 13 shown in Fig. 4. The transmission DBF unit 60 includes a SerDes (Serializer / Deserializer) 61 that performs serial and deserialization conversion, DBF units 62-1, 62-2, ... that perform DBF processing for each transmission beam, and a transmission power adjustment unit 66.

[0031] The transmission DBF unit 60 receives serial input of reception signals 21-1 to 21-nr that have been AD converted by AD converters 30-1 to 30-nr shown in Fig. 4. The serially input reception signals 21-1 to 21-nr are converted into parallel signals for each transmission beam by a SerDes 61, and input to DBF units 62-1, 62-2, .... The transmission DBF unit 60 performs parallel processing of signals for each transmission beam in the DBF units 62-1, 62-2, .... Here, the DBF unit 62-1 will be described, but the same processing as that of the DBF unit 62-1 is also performed in the other DBF units 62-2, ....

[0032] The distributor 63-1, which handles the distribution function of the DBF unit 62-1, copies the signal of the transmission beam to distribute the signal of the transmission beam to each of the transmission elements 16-1 to 16-ns. The DBF unit 62-1 multiplies each of the signals distributed to each of the transmission elements 16-1 to 16-ns by excitation coefficients 64-1-1, 64-1-2, ..., 64-1-ns. The excitation coefficients are weighting coefficients for adjusting the phase and amplitude of the signal. Taking into account the frequency characteristics, it is possible to multiply a different excitation coefficient for each certain frequency bandwidth, but here, the frequency characteristics of the transmission beam are ignored and the same excitation coefficient is multiplied to the signal of each transmission beam over the entire band. In other words, it is assumed that no frequency characteristics are given to the excitation coefficients 64-1-1, 64-1-2, ..., 64-1-ns, but different values ​​are given to the excitation coefficients 64-1-1, 64-1-2, ..., 64-1-ns.

[0033] The signals of the transmitting elements 16-1 to 16-ns output from the DBF unit 62-1 are added to the signals of the transmitting elements 16-1 to 16-ns output from the other DBF units 62-2, .... The transmission power adjustment unit 66 multiplies the signals of each transmitting element system, which are the signals after addition of the transmitting elements 16-1 to 16-ns, by a transmission power adjustment coefficient 65. As a result, the transmission power adjustment unit 66 adjusts the transmission power of each of the multiple transmitting elements 16-1 to 16-ns based on the transmission power adjustment coefficient 65. A method of determining the transmission power adjustment coefficient 65 will be described later.

[0034] The amplitude-related coefficients among the excitation coefficients and the transmission power adjustment coefficient 65 have the same function in the sense that they adjust the transmission power by weighting the amplitude of the transmission signal. For this reason, it is possible to combine them into one by including the transmission power adjustment coefficient 65 in the excitation coefficient. However, since the transmission power adjustment coefficient 65 has a different role from the excitation coefficient, in this disclosure, the transmission power adjustment coefficient 65 is a coefficient separate from the excitation coefficient.

[0035] The first role of the excitation coefficient is to determine the shape of a beam by keeping constant the power ratio determined by the amplitude between the transmitting element systems that contribute to the formation of one beam. The second role of the excitation coefficient is to keep constant the total power of the transmitting element systems that contribute to the formation of one beam regardless of the form of the beam to be formed, in order to prevent the power amplifiers of the transmitting element systems, i.e., the TWTAs 15-1 to 15-ns shown in FIG. 3, from being saturated when the received signal power input to the transmission beam is maximized. In contrast, the role of the transmission power adjustment coefficient 65 is to effectively utilize the power of the power amplifiers according to various combinations of beam formation. Thus, since the role of the transmission power adjustment coefficient 65 is different from that of the excitation coefficient, the transmission power adjustment coefficient 65 is set as a coefficient separate from the excitation coefficient in the satellite repeater 4.

[0036] In the first embodiment, the transmission DBF unit 60 is configured to multiply all transmission element systems by the same transmission power adjustment coefficient 65. That is, the number of transmission power adjustment coefficients 65 set for all transmission beams is one. On the other hand, since the number of excitation coefficients set is the product of the number of transmission beams and the number of transmission elements, it is clear that the number of transmission power adjustment coefficients 65 set is smaller than the number of excitation coefficients set. Therefore, even when the combination of beam formation is changed but the excitation coefficients for some beams are not changed, the satellite communication system 3 can reduce the number of coefficients that need to be changed, and can reduce the time required for calculation of the coefficients and control for setting the coefficients. The values ​​of the excitation coefficients and the transmission power adjustment coefficients 65 are parameter values ​​stored in the memory in the DCH / DBF 13 shown in FIG. 3. The values ​​of the excitation coefficients and the transmission power adjustment coefficients 65 stored in the memory can be freely rewritten by the telecommunication control unit 17 shown in FIG. 3.

[0037] Next, a description will be given of a method for determining the transmission power adjustment coefficient 65. In the first embodiment, the transmission power adjustment coefficient 65 is determined based on the power contribution rate due to the excitation coefficient of the transmission beam and the band allocation rate of the transmission beam.

[0038] Fig. 6 is an explanatory diagram of the power contribution rate due to the excitation coefficient, which is related to the determination of the transmission power adjustment coefficient 65 in the first embodiment. Here, taking the case of forming four transmission beams SBa, SBb, SBc, SBd as an example, attention is given to one of the transmission elements that contribute to the formation of all of the transmission beams SBa, SBb, SBc, SBd. The transmission element in the element arrangement 1-k shown in Fig. 1 corresponds to the one transmission element of interest. Fig. 6 shows an example of the power contribution rate (αs) due to the excitation coefficient for each of the transmission beams SBa, SBb, SBc, SBd in a bar graph.

[0039] As described above, in transmission beam formation by DBF, the excitation coefficient plays a role in determining the shape of the beam by keeping constant the power ratio determined by the amplitude between the transmission element systems contributing to one beam. Therefore, even when focusing on one transmission element, the power contribution rate due to the excitation coefficient of each transmission beam is determined. Figure 6 shows the power contribution rate due to the excitation coefficient when the target power is set to 1. The target power is the output power when the linearity of the output power of the power amplifier with respect to the input power to the power amplifier is maintained, and is a power that is somewhat lower than the saturation power. The power contribution rate due to the excitation coefficient is expressed as a ratio of the amount of power allocated to each beam that the transmission element contributes to forming from the transmission power of one transmission element to the target power.

[0040] In the example shown in Fig. 6, the power contribution ratios due to the excitation coefficients for the transmission beams SBa, SBb, SBc, and SBd are 0.2, 0.3, 0.3, and 0.5, respectively. As described above, the frequency characteristics of the transmission beams are ignored, and the same excitation coefficient is applied to each transmission beam across the entire band. Also, it is assumed that the same target power is obtained from multiple power amplifiers without considering variations in the performance of the power amplifiers due to aging, etc. As the value of the target power, a reference value that is the same output value obtained from multiple power amplifiers is used to calculate the power contribution ratios due to the excitation coefficients.

[0041] Fig. 7 is an explanatory diagram of the bandwidth allocation rate of a transmission beam related to the determination of the transmission power adjustment coefficient 65 in the first embodiment. The bandwidth allocation rate represents the proportion of the bandwidth allocated to each beam, with the upper bandwidth limit, which is the maximum bandwidth that can be allocated to a transmission beam, being 1. Fig. 7 shows an example of the bandwidth allocation rate (βs) of each transmission beam SBa, SBb, SBc, and SBd in a bar graph. In the example shown in Fig. 7, the bandwidth allocation rates of the transmission beams SBa, SBb, SBc, and SBd are 0.7, 0.4, 0.5, and 1.0, respectively.

[0042] 8 is an explanatory diagram of a transmission power allocation rate related to the determination of the transmission power adjustment coefficient 65 in the first embodiment. The transmission power allocation rate is the ratio of the transmission power allocated to each of a plurality of transmitting elements to the target power. The transmission power allocation rate is obtained by calculating the product of the power contribution rate (αs) due to the excitation coefficient and the bandwidth allocation rate (βs) for each transmission beam and accumulating the calculated products for all transmission beams.

[0043] Fig. 8 shows an example of determining the transmit power allocation rate for one transmitting element based on the power contribution rate due to the excitation coefficient shown in Fig. 6 and the band allocation rate shown in Fig. 7. In the example shown in Fig. 8, the transmit power allocation rate is determined to be Σ(αs × βs) = 0.91. Here, the frequency characteristics of the transmit beam are ignored, and the transmit power allocation rate is calculated using the result of simply multiplying the power contribution rate due to the excitation coefficient and the band allocation rate. When the frequency characteristics are taken into consideration, the transmit power allocation rate may be calculated using the result of integrating the power contribution rate due to the excitation coefficient over the band allocation rate interval.

[0044] Up to this point, the calculation of the power contribution rate, the band allocation rate, and the transmission power allocation rate based on the excitation coefficient has been explained by focusing on one transmitting element, but the same calculation as above is performed for all transmitting elements.

[0045] FIG. 9 is a diagram showing an example of the correspondence between the transmission beams and the transmitting elements, and the transmission power allocation rate of each transmitting element in the first embodiment. The correspondence between the transmission beams and the transmitting elements is such that the transmitting elements contribute to the formation of the transmission beam. FIG. 9 shows an example of the correspondence between the transmission beams SBa, SBb, SBc, and SBd and the transmitting elements 16-1 to 16-ns. In FIG. 9, circles indicate that the transmitting elements contribute to the formation of the transmission beam. In FIG. 9, transmitting element "1", transmitting element "2", ..., transmitting element "ns" respectively represent the transmitting elements 16-1 to 16-ns. PA1, PA2, ..., PAns respectively represent the transmission power allocation rate PA of the transmitting elements 16-1 to 16-ns.

[0046] The transmit power allocation rates PA1 to PAns of each transmitting element "1" to "ns" are calculated using information on the transmit beams marked with circles. For example, since transmitting element "1" contributes only to the formation of transmit beam SBa, transmit power allocation rate PA1 is determined by information on transmit beam SBa only. Note that while the bandwidth allocation rate (βs) of transmit beam SBa is the same for all transmitting elements "1" to "4" that contribute to beam formation, the power contribution rate (αs) due to the excitation coefficient differs for each of transmitting elements "1" to "4".

[0047] In the present disclosure, the maximum transmission power allocation rate is selected from the transmission power allocation rates PA1 to PAns calculated as described above. The transmitting element with the maximum transmission power allocation rate corresponds to the transmitting element that requires the highest transmission power among all the transmitting elements. In the example shown in Fig. 9, the transmitting element "3" that contributes to the formation of the four transmission beams SBa to SBd has the maximum transmission power allocation rate PA3, and the maximum value of the transmission power allocation rate PA3 is 0.91.

[0048] The value of the transmission power allocation rate PA3 of transmitting element "3", 0.91, is smaller than the target power of 1. This means that the transmission power of transmitting element "3" has a surplus with respect to the target power. In order to adjust the transmission power of the transmitting elements so as to use up this surplus, the satellite communication system 3 according to the present disclosure determines the reciprocal of the maximum value of the transmission power allocation rate as the transmission power adjustment coefficient 65. In this way, the transmission power adjustment coefficient 65 is calculated based on the maximum value of the transmission power allocation rate determined for each of the multiple transmitting elements. In the example described here, the transmission power adjustment coefficient 65 is determined as 1 / PA3=1 / 0.91.

[0049] As described with reference to FIG. 5, the same transmission power adjustment coefficient 65 is multiplied to all transmitting element systems. In the above example, the value of the transmission power adjustment coefficient 65 is greater than 1, but it goes without saying that depending on the combination of transmitting beams, the value of the transmission power adjustment coefficient 65 may be less than 1. The value of the transmission power allocation rate PA of each transmitting element may be a value corrected according to the variation in performance of the power amplifier due to aging deterioration or the like. In this case, the value of the transmission power allocation rate PA calculated as above can be corrected using the ratio between the reference value, which is the target power described with reference to FIG. 6, and the actual value, which is the actual target power.

[0050] In the first embodiment, the repeater control station 5 shown in Fig. 2 calculates the transmission power adjustment coefficient 65 described with reference to Fig. 6 to Fig. 9. Next, the configuration of the repeater control station 5 will be described.

[0051] 10 is a diagram showing a configuration example of a repeater control station 5 included in the satellite communication system 3 according to the first embodiment. The repeater control station 5 includes a transmission / reception antenna 70, an RF transmission / reception unit 71, a modem 72, and a telecommunication control unit 73, which are components for communicating with the satellite repeater 4, and a data transmission / reception unit 75, which is a component for communicating with the satellite communication system control station 6. The repeater control station 5 also includes a command generation unit 74, an excitation coefficient determination unit 76, and a power adjustment coefficient calculation unit 77.

[0052] The data transmitter / receiver 75 receives a beam forming request transmitted by the satellite communication system control station 6 constituting the terrestrial network. The command generator 74 generates a control command to be transmitted to the satellite repeater 4 based on the information of the beam forming request. The excitation coefficient determiner 76 determines an excitation coefficient that matches the beam forming request. The power adjustment coefficient calculator 77 calculates the transmission power adjustment coefficient 65 described with reference to Figs. 6 to 9. That is, the power adjustment coefficient calculator 77 calculates a transmission power allocation ratio, which is a ratio of the transmission power allocated to each of the multiple transmission elements to the target power, based on the excitation coefficient used in the DBF process and the frequency bandwidth allocated to each of the multiple transmission beams. The power adjustment coefficient calculator 77 calculates the transmission power adjustment coefficient 65 based on the maximum value of the transmission power allocation ratios calculated for each of the multiple transmission elements. The command generator 74 reflects the value of the excitation coefficient and the value of the transmission power adjustment coefficient 65 in the control command.

[0053] The tele-frame control unit 73 performs transmission processing to transmit a control command to the satellite repeater 4. The transmitting / receiving antenna 70 transmits the control command that has been processed by the modem 72 and the RF transmitting / receiving unit 71 to the satellite repeater 4. The transmitting / receiving antenna 70 also receives monitoring information of the satellite repeater 4 transmitted by telemetry. The tele-frame control unit 73 processes the monitoring information that has been processed by the modem 72 and the RF transmitting / receiving unit 71.

[0054] 11 is a flowchart showing a processing procedure of the satellite communication system 3 according to the first embodiment. In step S1, the repeater control station 5 of the satellite communication system 3 obtains a power contribution rate due to an excitation coefficient for each transmission beam. In step S2, the repeater control station 5 obtains a band allocation rate for each transmission beam. In step S3, the repeater control station 5 obtains a transmission power allocation rate for each transmission element based on the power contribution rate due to the excitation coefficient and the band allocation rate.

[0055] In step S4, the repeater control station 5 calculates a transmission power adjustment coefficient 65 based on the maximum value of the transmission power allocation rate of each transmitting element. The repeater control station 5 transmits a control command reflecting the calculated value of the transmission power adjustment coefficient 65 to the satellite repeater 4. The satellite repeater 4 receives the control command. In step S5, the satellite repeater 4 calculates the transmission power of each transmitting element based on the transmission power adjustment coefficient 65. With the above, the satellite communication system 3 ends the processing according to the procedure shown in FIG.

[0056] Next, the hardware configuration of the repeater control station 5 will be described. The command generation unit 74, the excitation coefficient determination unit 76, and the power adjustment coefficient calculation unit 77 are realized by processing circuits. The processing circuit may be a circuit in which a processor executes software, or may be a dedicated circuit. When the processing circuit is realized by software, the processing circuit is, for example, a control circuit shown in FIG. 12. FIG. 12 is a diagram showing an example of the configuration of a control circuit 80 in the first embodiment.

[0057] The control circuit 80 includes a processor 81 and a memory 82. The functions of the command generation unit 74, the excitation coefficient determination unit 76, and the power adjustment coefficient calculation unit 77 are realized by the processor 81 reading and executing a program stored in the memory 82. The processor 81 also outputs data such as calculation results to the volatile memory of the memory 82. The memory 82 is also used as a temporary memory for each process performed by the processor 81.

[0058] The processor 81 is a CPU (also called a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor)). The memory 82 is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc).

[0059] Each function of the command generating unit 74, the excitation coefficient determining unit 76, and the power adjustment coefficient calculating unit 77 may be realized by a processing circuit shown in Fig. 13, which is dedicated hardware. Fig. 13 is a diagram showing a configuration example of a processing circuit 90 in the first embodiment. The processing circuit 90 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a circuit that combines these.

[0060] Of the configuration shown in Fig. 10, processing functions other than the command generation unit 74, the excitation coefficient determination unit 76, and the power adjustment coefficient calculation unit 77 can also be configured by dedicated hardware. Each component realized by dedicated hardware is realized by a processing circuit 90 shown in Fig. 13. The processing function of the repeater control station 5 may be realized by combining the control circuit 80 and the processing circuit 90. The processing function of the satellite repeater 4 shown in Fig. 3 can also be configured by dedicated hardware. Each component realized by dedicated hardware is realized by the processing circuit 90 shown in Fig. 13. The processing function of the satellite repeater 4 may be realized by combining the control circuit 80 and the processing circuit 90.

[0061] According to the first embodiment, the satellite communication system 3 calculates a transmission power adjustment coefficient 65 to be commonly applied to all transmitting elements of the satellite repeater 4 according to the combination of beams required for the satellite communication system 3, and sets the transmission power adjustment coefficient 65 to the satellite repeater 4. The satellite repeater 4 adjusts the transmission power of each transmitting element based on the transmission power adjustment coefficient 65. The satellite communication system 3 can effectively use the transmission power while considering the target power of the power amplifier provided in the satellite repeater 4, and therefore can optimize the transmission power according to the combination of beams required, and can improve the frequency utilization efficiency of the satellite communication system 3. This allows the satellite communication system 3 to improve the utilization efficiency of the power resources in the satellite repeater 4, and thus achieves the effect of improving the quality of communication. In addition, the satellite communication system 3 can reduce the amount of calculation required to adjust the transmission power, and can also reduce the number of parameters whose settings need to be changed.

[0062] Embodiment 2 In the second embodiment, a satellite repeater having a different configuration from the satellite repeater 4 shown in Fig. 3 will be described. Fig. 14 is a diagram showing a configuration example of a satellite repeater 4A included in a satellite communication system 3 according to the second embodiment. In the second embodiment, the same components as those in the first embodiment are given the same reference numerals, and the configuration different from the first embodiment will be mainly described.

[0063] The satellite repeater 4A includes a DCH / DBF 13A that is different from the DCH / DBF 13 shown in Fig. 3. A modem 20A is provided between the DCH / DBF 13A and the telecommunication control unit 17. The control antenna 18, RF transceiver unit 19, and modem 20 shown in Fig. 3 are not included in the satellite repeater 4A. The satellite repeater 4A performs beam forming using DBF when receiving control commands transmitted from the repeater control station 5 and when transmitting monitoring information to the repeater control station 5 by telemetry.

[0064] The satellite repeater 4A receives a control command signal via a receiving beam by using the receiving elements 10-1 to 10-nr. The control command signal is demodulated and decoded by the modem 20A and then passed to the tele-frame control unit 17. A telemetry signal, which is a monitoring information signal from the tele-frame control unit 17, is modulated and coded by the modem 20A and transmitted to the repeater control station 5 via a transmitting beam by using the transmitting elements 16-1 to 16-ns.

[0065] Next, the configuration of the DCH / DBF 13A will be described. Fig. 15 is a diagram showing an example of the configuration of the DCH / DBF 13A possessed by the satellite repeater 4A shown in Fig. 14. The DCH / DBF 13A includes a switch circuit 50A different from the switch circuit 50 shown in Fig. 4. The reception DBF unit 40 combines signals in demultiplexing units of the reception beam. The switch circuit 50A extracts signals in a partial frequency band of the reception beam including a control command signal from the signals in demultiplexing units of the reception beam. The switch circuit 50A outputs the extracted signal to the modem 20A.

[0066] When a telemetry signal is input from the tele-frame control unit 17 to the switch circuit 50A, the telemetry signal is output to the transmission DBF unit 60 as a signal in a partial frequency band of the transmission beam. The control command signal output from the DCH / DBF 13A and the telemetry signal input to the DCH / DBF 13A are digital signals. Therefore, the modem 20A shown in FIG. 14 does not require a circuit for DA conversion and a circuit for AD conversion.

[0067] The satellite repeater 4A can transmit telemetry signals via a transmission beam by DBF, and can receive control command signals via a reception beam by DBF, as in the case of user communication. The frequency bands of the transmission beams and reception beams used by a communication satellite for user communication are generally higher than the frequency bands used by the communication satellite for telecommunication control. According to the second embodiment, the satellite communication system 3 can transmit the excitation coefficient and the transmission power adjustment coefficient 65 to the satellite repeater 4A at high speed by using a high frequency band for wideband signal transmission and reception of the telecommunication signal. This allows the satellite communication system 3 to reduce the time required to control the satellite repeater 4A.

[0068] Embodiment 3 In the first embodiment, the satellite communication system 3 determines the transmission power adjustment coefficient 65 using the maximum value of the transmission power allocation rate PA as shown in Fig. 9. In the third embodiment, an example will be described in which the correspondence between the transmission beams and the transmitting elements is examined from the combination of the transmission beams to be formed to determine the transmission power adjustment coefficient in order to further improve the frequency utilization efficiency of the satellite communication system 3. In the third embodiment, the same components as those in the first or second embodiment are denoted by the same reference numerals, and the configuration different from the first or second embodiment will be mainly described.

[0069] In the third embodiment, the power adjustment coefficient calculation unit 77 of the repeater control station 5 shown in FIG. 10 divides a plurality of transmitting elements into two or more transmitting element groups by grouping transmitting elements that contribute to the formation of a common transmitting beam for transmitting beams formed using common transmitting elements, and calculates a transmission power adjustment coefficient for each transmitting element group based on the maximum value of the transmission power allocation rate for each transmitting element group.

[0070] Fig. 16 is a diagram showing an example of the correspondence between transmission beams and transmitting elements, and the transmission power allocation ratio of each transmitting element in embodiment 3. Fig. 16 shows an example of the correspondence between five transmission beams SBa, SBb, SBc, SBd, and SBe and transmitting elements 16-1 to 16-ns. The circles in Fig. 16 indicate that a transmitting element contributes to forming a transmission beam, as in Fig. 9.

[0071] In the third embodiment, first, a transmitting element having the maximum transmission power allocation rate PA is determined from among all transmitting elements 16-1 to 16-ns. In the example shown in Fig. 16, it is assumed that transmitting element "2" has the maximum transmission power allocation rate PA2. Next, from among the transmitting elements excluding the transmitting element having the maximum transmission power allocation rate PA, transmitting elements having an association with the transmitting element having the maximum transmission power allocation rate PA are extracted.

[0072] In the example shown in FIG. 16, transmitting element "2" contributes to the formation of two transmission beams SBa and SBe. Transmitting element "1" also contributes to the formation of the transmission beam SBa. Transmitting element "1", which contributes to the formation of the transmission beam SBa common to the transmission beam SBa contributed to by transmitting element "2", is associated with transmitting element "2". In addition, transmitting element "3", which contributes to the formation of the transmission beam SBe common to the transmission beam SBe contributed to by transmitting element "2", is also associated with transmitting element "2". Transmitting element "3" contributes to the formation of the transmission beam SBc in addition to the transmission beam SBe. Transmitting element "4", which contributes to the formation of the transmission beam SBc common to the transmission beam SBc contributed to by transmitting element "3", is also associated with transmitting element "2".

[0073] As a result, three transmitting elements "1," "3," and "4" are extracted as transmitting elements related to transmitting element "2." Note that the double-headed arrows in Fig. 16 indicate that for transmitting beams formed using a common transmitting element, transmitting elements that contribute to the formation of the common transmitting beam are linked together to extract related transmitting elements.

[0074] The transmitting element "2" and the extracted transmitting elements "1", "3", and "4" are regarded as a first transmitting element group, which is one of transmitting element groups having a relationship with each other. The reciprocal of the maximum value of the transmitting power allocation rate PA of each transmitting element included in the first transmitting element group is determined as the transmitting power adjustment coefficient of each transmitting element included in the first transmitting element group. In the case of the example shown in FIG. 16, since the maximum value of the transmitting power allocation rate PA in the first transmitting element group is the transmitting power allocation rate PA2 of the transmitting element "2", the power adjustment coefficient calculation unit 77 calculates the reciprocal of the transmitting power allocation rate PA2 as the transmitting power adjustment coefficient of each transmitting element included in the first transmitting element group.

[0075] Next, the transmitting element with the maximum transmission power allocation rate PA is determined from among transmitting elements "5" to "ns" which are transmitting elements other than the first transmitting element group among all transmitting elements. In the example shown in FIG. 16, it is assumed that transmitting element "6" has the maximum transmission power allocation rate PA6. Next, similarly to the case of the first transmitting element group, transmitting elements having an association with transmitting element "6" are extracted, and transmitting element "6" and the extracted transmitting element are regarded as a second transmitting element group which is one of transmitting element groups other than the first transmitting element group. In the example shown in FIG. 16, it is assumed that transmitting elements "5" to "ns" are the second transmitting element group.

[0076] Similarly to the first transmitting element group, the reciprocal of the maximum value of the transmission power allocation rate PA of each transmitting element included in the second transmitting element group is determined as the transmission power adjustment coefficient of each transmitting element included in the second transmitting element group. In the example shown in Fig. 16, since the maximum value of the transmission power allocation rate PA in the second transmitting element group is the transmission power allocation rate PA6 of the transmitting element "6", the power adjustment coefficient calculation unit 77 calculates the reciprocal of the transmission power allocation rate PA6 as the transmission power adjustment coefficient of each transmitting element included in the second transmitting element group.

[0077] In the example shown in FIG. 16, it is assumed that all transmitting elements are extracted by the first transmitting element group and the second transmitting element group. If there are remaining transmitting elements at the time when the first transmitting element group and the second transmitting element group are extracted, the power adjustment coefficient calculation unit 77 repeats the extraction of the transmitting element group and the determination of the transmission power adjustment coefficient, as in the case of the first transmitting element group and the second transmitting element group. The power adjustment coefficient calculation unit 77 repeats the extraction of the transmitting element group and the determination of the transmission power adjustment coefficient until all transmitting elements are extracted as transmitting element groups. In this way, the power adjustment coefficient calculation unit 77 divides all transmitting elements into two or more transmitting element groups, and calculates the transmission power adjustment coefficient for each transmitting element group based on the maximum value of the transmission power allocation rate for each transmitting element group.

[0078] Next, a configuration of a transmission DBF unit for utilizing the transmission power adjustment coefficient determined for each transmitting element group in the satellite repeater 4 will be described. Fig. 17 is a diagram showing a configuration example of a transmission DBF unit 60B included in the satellite repeater 4 of the satellite communication system 3 according to the third embodiment. In the third embodiment, a transmission power adjustment unit 66B of the transmission DBF unit 60B adjusts the transmission power based on the transmission power adjustment coefficients 65-1, 65-2, ..., 65-ns calculated for each transmitting element group. That is, the transmission power adjustment unit 66B is configured to be able to multiply the signal of each transmitting element system by the transmission power adjustment coefficients 65-1, 65-2, ..., 65-ns that differ for each transmitting element group.

[0079] According to the third embodiment, the satellite communication system 3 divides the transmitting elements into two or more transmitting element groups based on the relevance between the transmitting elements, and adjusts the transmission power using the transmission power adjustment coefficient determined for each transmitting element group. For example, since the transmitting elements of the second transmitting element group have a smaller transmission power allocation rate PA than the transmitting elements of the first transmitting element group, the transmission power adjustment coefficient for the second transmitting element group is larger than the transmission power adjustment coefficient for the first transmitting element group. In this way, the transmission power for the transmitting element group can be increased each time the transmitting element group is increased. This enables the satellite communication system 3 to improve frequency utilization efficiency.

[0080] Embodiment 4 In the first to third embodiments, the satellite communication system 3 determines the transmission power adjustment coefficient based on the beam forming request from the satellite communication system control station 6 shown in Fig. 2. In the fourth embodiment, the transmission power adjustment coefficient is determined based not only on the beam forming request but also on the transmission power of the satellite repeater 4 actually used in the operation of the satellite communication system 3, thereby making it possible to determine a transmission power adjustment coefficient that is more suited to the actual situation. In the fourth embodiment, the same components as those in the first to third embodiments are denoted by the same reference numerals, and the following mainly describes the configurations that are different from those in the first to third embodiments.

[0081] 18 is a diagram showing an example of the correspondence between transmission beams and transmitting elements, and the power utilization rate of each transmitting element in the fourth embodiment. In the fourth embodiment, the satellite communication system 3 calculates the power utilization rate, which is the ratio of the power used by each of the multiple transmitting elements to the target power, and calculates the transmission power adjustment coefficient based on the maximum value of the power utilization rates calculated for each of the multiple transmitting elements. The power utilization rate indicates the result of monitoring the power actually used by each of the multiple transmitting elements.

[0082] The correspondence between the transmission beams and transmitting elements shown in Fig. 18 is determined according to a beam forming request, similar to the case shown in Fig. 9. In Fig. 18, the power utilization rate PU of a transmitting element is a power value obtained by monitoring the power used by each transmitting element, and is expressed as a ratio to the target power TP of the transmitting element. The target power TP is the same as the actual value that is the actual target power described with reference to Fig. 9. For the sake of simplicity, it is assumed here that all transmitting elements have the same reference value that is the same target power. The power utilization rate PU is the ratio of the power monitor value MP to the target power TP. In other words, the relationship PU=MP / TP holds. A maximum value is extracted from the power utilization rate PU of each transmitting element.

[0083] In the example shown in FIG. 18, the PU4 value of the transmitting element "4" is the maximum value. In the fourth embodiment, the satellite communication system 3 obtains the inverse of the maximum value of the power utilization rate as the transmission power adjustment coefficient. In the example described here, the transmission power adjustment coefficient is determined as 1 / PA4. Here, in order to prevent the transmission power adjustment coefficient from becoming too large due to the value of PU4 being too small, or to prevent the transmission power adjustment coefficient from being unable to be calculated, a lower limit value of the power utilization rate PU used in the calculation of the transmission power adjustment coefficient is set. When the maximum value of PU4 is smaller than the lower limit value, the satellite communication system 3 determines the transmission power adjustment coefficient using the lower limit value. The lower limit value is a value determined in advance.

[0084] Next, the configuration of the satellite repeater in the fourth embodiment will be described. Fig. 19 is a diagram showing an example of the configuration of a satellite repeater 4C included in a satellite communication system 3 according to the fourth embodiment. The satellite repeater 4C includes a power adjustment coefficient calculation unit 23 in addition to the same configuration as the satellite repeater 4 shown in Fig. 3. The power adjustment coefficient calculation unit 23 calculates a power utilization rate as described above, and calculates a transmission power adjustment coefficient based on the maximum value of the power utilization rates calculated for each of a plurality of transmitting elements.

[0085] The tele-frame control unit 17 periodically acquires the measured values ​​of the output power of the TWTAs 15-1 to 15-ns as one of the monitoring items of the satellite repeater 4C. The power adjustment coefficient calculation unit 23 monitors the measured values ​​of the output power collected by the tele-frame control unit 17. The power adjustment coefficient calculation unit 23 calculates a power utilization rate PU based on the target power TP and a power monitor value MP, which is the monitored measured value, and calculates a transmission power adjustment coefficient based on the power utilization rate PU.

[0086] The power adjustment coefficient calculation unit 23 determines the transmission power adjustment coefficient by the above-mentioned method. In order to prevent the value of the transmission power adjustment coefficient from fluctuating frequently and greatly, the power adjustment coefficient calculation unit 23 may calculate the transmission power adjustment coefficient by averaging the monitored values ​​or by controlling the amount of fluctuation of the value with a threshold, i.e., controlling with hysteresis. The transmission power adjustment coefficient calculated by the power adjustment coefficient calculation unit 23 is set in the DCH / DBF 13 via the telecommunication control unit 17. In this way, the transmission power adjustment coefficient 65 determined based on the transmission power of the satellite repeater 4 actually used in operating the satellite communication system 3 is set in the transmission DBF unit 60 shown in FIG. 5.

[0087] Fig. 20 is a flowchart showing a processing procedure of the satellite communication system 3 according to the fourth embodiment. In step S11, the satellite repeater 4C of the satellite communication system 3 determines the power utilization rate of each transmitting element by the power adjustment coefficient calculation unit 23. In step S12, the satellite repeater 4C calculates the transmission power adjustment coefficient 65 by the power adjustment coefficient calculation unit 23 based on the maximum value of the power utilization rate or the lower limit value of the power utilization rate of each transmitting element. In step S13, the satellite repeater 4C calculates the transmission power of each transmitting element based on the transmission power adjustment coefficient 65. With the above, the satellite communication system 3 ends the processing according to the procedure shown in Fig. 20.

[0088] The function of the power adjustment coefficient calculation unit 23 is realized by a control circuit 80 shown in Fig. 12 or a processing circuit 90 shown in Fig. 13. The function of the power adjustment coefficient calculation unit 23 may be realized by a combination of the control circuit 80 and the processing circuit 90.

[0089] In the fourth embodiment, since the transmission power adjustment coefficient 65 can be calculated in the satellite repeater 4C, the power adjustment coefficient calculation unit 77 may be deleted from the repeater control station 5 shown in Fig. 10. However, even in the fourth embodiment, the power adjustment coefficient calculation unit 77 may be provided in the repeater control station 5. In this case, the satellite communication system 3 may treat the value of the transmission power adjustment coefficient 65 calculated by the power adjustment coefficient calculation unit 77 of the repeater control station 5 as an initial value, and thereafter, the value of the transmission power adjustment coefficient 65 may be replaced with the value calculated by the power adjustment coefficient calculation unit 23 of the satellite repeater 4C to adjust the transmission power.

[0090] It goes without saying that the power adjustment coefficient calculation unit 23 may calculate the transmission power adjustment coefficient for each transmitting element described in the third embodiment from the monitored power value, and apply the obtained transmission power adjustment coefficient to the transmission DBF unit 60B shown in FIG. 17.

[0091] In the fourth embodiment, the satellite communication system 3 may divide the transmitting elements into two or more transmitting element groups based on the relevance between the transmitting elements, and adjust the transmission power using a transmission power adjustment coefficient determined for each transmitting element group, as in the third embodiment. In this case, the satellite communication system 3 can improve the frequency utilization efficiency.

[0092] According to the fourth embodiment, the satellite communication system 3 can determine the transmission power adjustment coefficient 65 by using the transmission power actually used. When the utilization rate of user communication is low, that is, when the frequency band actually used is small, the satellite communication system 3 has a surplus in transmission power, and can adjust the transmission power in accordance with the surplus. This allows the satellite communication system 3 to further improve frequency utilization efficiency. Also, when the actual transmission power used is a transmission power that exceeds the expected transmission power, the satellite communication system 3 can control the transmission power to be reduced to the target power. This allows the satellite communication system 3 to avoid distortion of the communication signal and prevent deterioration of the signal quality.

[0093] Embodiment 5. In the fifth embodiment, an example in which the second embodiment is combined with the fourth embodiment will be described. Fig. 21 is a diagram showing a configuration example of a satellite repeater 4D included in a satellite communication system 3 according to the fifth embodiment. In the fifth embodiment, the same components as those in the first to fourth embodiments are given the same reference numerals, and the configuration different from the first to fourth embodiments will be mainly described.

[0094] The satellite repeater 4D includes a DCH / DBF 13D similar to the DCH / DBF 13A shown in Fig. 14, and a modem 20D similar to the modem 20A shown in Fig. 14. The satellite repeater 4D also includes a power adjustment coefficient calculation unit 23 similar to that of the fourth embodiment. That is, the satellite repeater 4D is configured similarly to the satellite repeater 4A shown in Fig. 14, to which the power adjustment coefficient calculation unit 23 has been added.

[0095] Like the satellite repeater 4A of the second embodiment, the satellite repeater 4D can transmit a telemetry signal via a transmission beam by DBF and can receive a control command signal via a reception beam by DBF. This allows the satellite communication system 3 to reduce the time required to control the satellite repeater 4D. Also, like the fourth embodiment, the satellite repeater 4D calculates a transmission power adjustment coefficient by the power adjustment coefficient calculation unit 23. The satellite communication system 3 can improve frequency utilization efficiency and prevent deterioration of signal quality.

[0096] Embodiment 6 22 is a diagram showing a configuration example of a transmission DBF unit 60E included in a satellite repeater 4 of a satellite communication system 3 according to a sixth embodiment. In the sixth embodiment, a power adjustment coefficient calculation unit 67 is provided inside the transmission DBF unit 60E. In the sixth embodiment, the same components as those in the first to fifth embodiments are given the same reference numerals, and the configuration different from the first to fifth embodiments will be mainly described.

[0097] The transmission DBF unit 60E has a configuration similar to that of the transmission DBF unit 60 shown in Fig. 5, to which a power adjustment coefficient calculation unit 67 has been added. The power adjustment coefficient calculation unit 67 calculates a power utilization rate, which is the ratio of the power used by each of the multiple transmission elements to the target power, and calculates a transmission power adjustment coefficient 65 based on the maximum value of the power utilization rates calculated for each of the multiple transmission elements.

[0098] The power adjustment coefficient calculation unit 67 monitors the transmission signals 22-1, 22-2, ..., 22-ns output from the transmission DBF unit 60E, i.e., the signals for each transmission element system. The power adjustment coefficient calculation unit 67 can calculate the transmission power actually used from the monitored signals. Therefore, the power adjustment coefficient calculation unit 67 can calculate the transmission power adjustment coefficient 65 by the same calculation as the power adjustment coefficient calculation unit 23 described in the fourth embodiment. This allows the satellite communication system 3 to shorten the time required to control the satellite repeater 4, as in the fourth embodiment. Furthermore, the satellite communication system 3 can improve frequency utilization efficiency and prevent deterioration of signal quality, as in the fourth embodiment.

[0099] The function of the power adjustment coefficient calculation unit 67 is realized by a control circuit 80 shown in Fig. 12 or a processing circuit 90 shown in Fig. 13. The function of the power adjustment coefficient calculation unit 67 may be realized by a combination of the control circuit 80 and the processing circuit 90.

[0100] Needless to say, the power adjustment coefficient calculation unit 67 may calculate the transmission power adjustment coefficient for each transmitting element described in the third embodiment from the monitored power value, and apply the obtained transmission power adjustment coefficient to the transmission DBF unit 60E shown in Fig. 22. In this case, the transmission DBF unit 60E is made to have a transmission power adjustment coefficient for each transmitting element system, like the transmission power adjustment coefficients 65-1, 65-2, ..., 65-ns shown in Fig. 17.

[0101] Embodiment 7 In the first to sixth embodiments, an operation of forming a transmission beam by increasing the transmission power of the satellite repeaters 4, 4A, 4C, and 4D when there is a margin of transmission power has been described. However, there may be cases where it is not desired to increase the signal strength of the formed beam in order to avoid radio interference with systems other than the satellite communication system 3 as much as possible, or to avoid interception of communication signals as much as possible. In the seventh embodiment, a method and configuration for dealing with such cases will be described. In the seventh embodiment, the same components as those in the first to sixth embodiments are given the same reference numerals, and the configurations different from those in the first to sixth embodiments will be mainly described.

[0102] 23 is a diagram showing an example of the correspondence between transmission beams and transmitting elements and the transmission power allocation ratio of each transmitting element in the seventh embodiment. In the seventh embodiment, the satellite communication system 3 adjusts the transmission power of each of the multiple transmitting elements by adjusting the transmission power for each transmission beam based on the transmission power adjustment coefficient. In addition, the satellite communication system 3 excludes some of the multiple transmission beams from the targets for adjusting the transmission power.

[0103] Fig. 23 shows an example of the correspondence between four transmission beams SBa, SBb, SBc, and SBd and the transmitting elements 16-1 to 16-ns. The circles in Fig. 23 indicate that the transmitting elements contribute to the formation of the transmission beam, as in Fig. 9. In the example shown in Fig. 23, it is assumed that the transmission beam SBb, which is one of the transmission beams SBa, SBb, SBc, and SBd, is a transmission beam that is excluded from the targets for adjusting the transmission power.

[0104] In the seventh embodiment, the power adjustment coefficient calculation unit 77 of the repeater control station 5 shown in FIG. 10 calculates an exclusion target power TPex, which is power obtained by subtracting the transmission power allocation rate for the transmission beam SBb from the target power 1 described in the first embodiment. In addition, the power adjustment coefficient calculation unit 77 calculates the transmission power allocation rates PA1 to PAns for each of the transmission elements "1" to "ns" by excluding the corresponding relationship with each of the transmission elements "1" to "ns" for the transmission beam SBb. The power adjustment coefficient calculation unit 77 extracts an exclusion transmission power allocation rate PAex, which is the maximum value of the transmission power allocation rates, from the calculated transmission power allocation rates PA1 to PAns. The transmission power adjustment coefficient is calculated as TPex / PAex. In the example shown in FIG. 23, PAex=PA3. In this way, the power adjustment coefficient calculation unit 77 calculates the transmission power adjustment coefficient by excluding the power that contributes to the formation of the transmission beam that is excluded from the adjustment target from the calculation.

[0105] The satellite communication system 3 adjusts the transmission power of each of the transmission beams SBa, SBc, and SBd based on the transmission power adjustment coefficient, but does not adjust the transmission power of the transmission beam SBb.

[0106] Next, a configuration of a transmission DBF unit for excluding some transmission beams from targets for adjusting transmission power and adjusting the transmission power for each transmission beam based on a transmission power adjustment coefficient will be described. Fig. 24 is a diagram showing a configuration example of a transmission DBF unit 60F included in a satellite repeater 4 of a satellite communication system 3 according to a seventh embodiment.

[0107] The DBF unit 62-1 of the transmission DBF unit 60F includes a transmission power adjustment unit 66F-1 that adjusts the transmission power based on a transmission power adjustment coefficient 65F. Here, the DBF unit 62-1 will be described, but the other DBF units 62-2, ... also have a similar configuration to the DBF unit 62-1. The transmission DBF unit 60F includes the transmission power adjustment units 66F-1, ... that perform DBF processing for each transmission beam, and multiplies the signal for each transmission beam by the transmission power adjustment coefficient 65F. Among the DBF units 62-1, 62-2, ..., the DBF units for the transmission beams excluded from the targets for adjusting the transmission power multiply the signal by 1, which is a coefficient for not weighting, instead of the transmission power adjustment coefficient 65F. In this way, the transmission power adjustment units 66F-1, ... adjust the transmission power for each transmission beam based on the transmission power adjustment coefficient 65F to adjust the transmission power of each of the multiple transmission elements, and exclude some of the multiple transmission beams from the targets for adjusting the transmission power.

[0108] In the first to sixth embodiments, the transmission power is adjusted based on the transmission power adjustment coefficient on a transmission element basis. In the seventh embodiment, however, the satellite communication system 3 adjusts the transmission power based on the transmission power adjustment coefficient 65F on a transmission beam basis.

[0109] According to the seventh embodiment, the satellite communication system 3 can prevent some of the beams from being affected by the adjustment of the transmission power based on the transmission power adjustment coefficient 65F. This allows the satellite communication system 3 not to increase the signal strength of some of the beams, thereby avoiding radio interference with systems other than the satellite communication system 3. Furthermore, the satellite communication system 3 can avoid interception of the communication signal.

[0110] The satellite communication system 3 may combine the process of adjusting the transmission power for each transmission beam as in the seventh embodiment and excluding some beams from the targets for adjusting the transmission power with any of the processes in the first to sixth embodiments. In this case, the satellite communication system 3 can also avoid radio interference and eavesdropping on the communication signal.

[0111] Embodiment 8 In the first to seventh embodiments, the direction, shape, and frequency band of each beam are determined for each operation request of the satellite communication system 3, and the transmission power of the transmission beam is optimized according to the combination of beams. In contrast, in beam hopping in the satellite repeater 4, which has been studied in recent years, it is required to change the direction, shape, and frequency band of each beam in a short period of time. To achieve this, it is necessary to set a plurality of beam patterns, which are irradiation patterns of a plurality of beams, in the satellite repeater 4 and switch the beam patterns sequentially. In the eighth embodiment, a method and configuration for handling such beam hopping will be described. In the eighth embodiment, the same components as those in the first to seventh embodiments are assigned the same reference numerals, and the configuration different from the first to seventh embodiments will be mainly described.

[0112] Fig. 25 is an explanatory diagram of the operation of the satellite repeater 4 of the satellite communication system 3 according to the eighth embodiment. Here, it is assumed that the satellite repeater 4 performs beam hopping in a service link to a user earth station. Fig. 25 shows an example of a time series of a reception beam pattern, which is a beam pattern of a reception beam formed by the satellite repeater 4, and a time series of a transmission beam pattern, which is a beam pattern of a transmission beam formed by the satellite repeater 4.

[0113] In the example shown in FIG. 25, the satellite repeater 4 transitions the beam pattern of the reception beam from beam pattern 100-1, 101-1, 100-2, 101-2, ... to beam pattern 100-1 and beam pattern 100-2 are the same beam pattern. Such a beam pattern is referred to as a first reception beam pattern. Beam pattern 101-1 and beam pattern 101-2 are the same beam pattern and are different from the first reception beam pattern. Such a beam pattern is referred to as a second reception beam pattern. The satellite repeater 4 forms a reception beam by alternately switching between the first reception beam pattern and the second reception beam pattern.

[0114] In the example shown in FIG. 25, the satellite repeater 4 transitions the beam pattern of the transmission beam from beam pattern 102-1, 103-1, 102-2, 103-2, ... to beam pattern 102-1 and beam pattern 102-2, which are the same beam pattern. Such a beam pattern is referred to as a first transmission beam pattern. Beam pattern 103-1 and beam pattern 103-2 are the same beam pattern, which is different from the first transmission beam pattern. Such a beam pattern is referred to as a second transmission beam pattern.

[0115] The time length of the first reception beam pattern and the time length of the second reception beam pattern may be different from each other. The time length of the first reception beam pattern and the time length of the first transmission beam pattern are the same. The time length of the second reception beam pattern and the time length of the second transmission beam pattern are the same. In addition, the user earth station transmits and receives communication signals in accordance with the timing at which the satellite repeater 4 switches the beam pattern. The satellite repeater 4 transmits the signal received by the reception beam by a transmission beam having the same time length as the reception beam. As a result, a timing difference corresponding to the relay processing delay inside the satellite repeater 4 occurs between the reception beam pattern and the transmission beam pattern. Although not shown in FIG. 25, a guard time is included between each reception beam pattern and each transmission beam pattern to absorb an error in the transmission and reception timing with multiple earth stations or to perform processing to switch the beam pattern inside the satellite repeater 4.

[0116] The satellite repeater 4 is not limited to one that alternates between two types of receiving beam patterns. The satellite repeater 4 may be one that switches the receiving beam pattern from a plurality of beam patterns in a time-division manner to form a plurality of receiving beams. Furthermore, the satellite repeater 4 is not limited to one that alternates between two types of transmitting beam patterns. The satellite repeater 4 may be one that switches the transmitting beam pattern from a plurality of beam patterns in a time-division manner to form a plurality of transmitting beams.

[0117] In the eighth embodiment, the power adjustment coefficient calculation unit 77 of the repeater control station 5 shown in Fig. 10 calculates a transmission power adjustment coefficient corresponding to each of a plurality of beam patterns. The satellite communication system 3 adjusts the transmission power by switching the transmission power adjustment coefficient in accordance with switching of the beam pattern.

[0118] Next, a configuration of a DCH / DBF for adjusting transmission power by switching a transmission power adjustment coefficient in accordance with switching of beam patterns will be described. Fig. 26 is a diagram showing a configuration example of a DCH / DBF 13G included in a satellite repeater 4 of a satellite communication system 3 according to an eighth embodiment. The DCH / DBF 13G includes AD converters 30-1 to 30-nr, DA converters 31-1 to 31-ns, a receiving DBF unit 40G, a switching circuit 50G, a transmitting DBF unit 60G, and a scheduler 120.

[0119] The reception DBF unit 40G includes parameter setting areas 111-1, 111-2, etc. corresponding to each of a plurality of reception beam patterns. The reception DBF unit 40G also includes the same functions as the reception DBF unit 40 shown in FIG. 4. In the parameter setting areas 111-1, 111-2, etc., excitation coefficients and the like corresponding to the reception beam patterns are set. In the reception DBF unit 40G, the same number of parameter setting areas 111-1, 111-2, etc. as the number of types of reception beam patterns are used. When switching between two types of reception beam patterns, two parameter setting areas 111-1, 111-2 are used.

[0120] The switch circuit 50G includes parameter setting areas 112-1, 112-2, ... corresponding to each of a plurality of combinations of a receive beam pattern and a transmit beam pattern. The switch circuit 50G also includes the same functions as the switch circuit 50 shown in FIG. 4. The parameter setting areas 112-1, 112-2, ... are set with information indicating a connection relationship between a receive beam and a transmit beam according to a combination of a receive beam pattern and a transmit beam pattern. The switch circuit 50G uses parameter setting areas 112-1, 112-2, ... in the same number as the number of combinations of a receive beam pattern and a transmit beam pattern. When switching between two types of receive beam patterns and switching between two types of transmit beam patterns, two parameter setting areas 112-1, 112-2 are used.

[0121] The transmission DBF unit 60G includes parameter setting areas 113-1, 113-2, etc. corresponding to each of a plurality of transmission beam patterns. The transmission DBF unit 60G also includes the same functions as the transmission DBF unit 60 shown in FIG. 4. In the parameter setting areas 113-1, 113-2, etc., excitation coefficients and the like corresponding to the transmission beam patterns and transmission power adjustment coefficients corresponding to the transmission beam patterns are set. In the transmission DBF unit 60G, the same number of parameter setting areas 113-1, 113-2, etc. as the number of types of transmission beam patterns are used. When switching between two types of transmission beam patterns, two parameter setting areas 113-1, 113-2 are used.

[0122] The scheduler 120 switches between the parameter setting areas 111-1, 111-2, ... of the reception DBF unit 40G, the parameter setting areas 112-1, 112-2, ... of the switch circuit 50G, and the parameter setting areas 113-1, 113-2, ... of the transmission DBF unit 60G. The scheduler 120 holds information on the switching timing of the beam pattern. The information on the switching timing is set in the satellite repeater 4 by the terrestrial repeater control station 5 together with information on the beam pattern, etc. The scheduler 120 switches between the parameter setting areas 111-1, 111-2, ... referred to by the reception DBF unit 40G, the parameter setting areas 112-1, 112-2, ... referred to by the switch circuit 50G, and the parameter setting areas 113-1, 113-2, ... referred to by the transmission DBF unit 60G at the switching timing.

[0123] The parameter setting areas 111-1, 111-2, ... can be easily switched by changing the reference address used by the reception DBF unit 40G to refer to the excitation coefficients, etc. The parameter setting areas 112-1, 112-2, ... can be easily switched by changing the reference address used by the switch circuit 50G to refer to information indicating the connection relationship between the reception beams and the transmission beams, etc. The parameter setting areas 113-1, 113-2, ... can be easily switched by changing the reference address used by the transmission DBF unit 60G to refer to the excitation coefficients, etc. and the transmission power adjustment coefficients.

[0124] The scheduler 120 simultaneously switches between the parameter setting areas 111-1, 111-2, ..., between the parameter setting areas 112-1, 112-2, ..., and between the parameter setting areas 113-1, 113-2, .... The scheduler 120 performs these switches within a guard time for performing a process of switching beam patterns inside the satellite repeater 4. In order to shorten the guard time, the scheduler 120 may shift each switching timing little by little, taking into consideration the processing time required for each switching process. In addition, the method of determining the transmission power adjustment coefficient for each transmission beam pattern can be the method described in the first, third, or seventh embodiment.

[0125] According to the eighth embodiment, the satellite communication system 3 calculates a transmission power adjustment coefficient for each of a plurality of beam patterns, and adjusts the transmission power by switching the transmission power adjustment coefficient in conjunction with switching of the beam pattern. This allows the satellite communication system 3 to improve the utilization efficiency of power resources in the satellite repeater 4 even when performing beam hopping. The satellite communication system 3 may combine the process of switching the transmission power adjustment coefficient in conjunction with switching of the beam pattern, as in the eighth embodiment, with any of the processes in the first to seventh embodiments. In this case as well, the satellite communication system 3 can perform beam hopping and improve the utilization efficiency of power resources in the satellite repeater 4.

[0126] This disclosure is applicable to a non-terrestrial network (NTN) that performs beamforming using DBF. This disclosure is applicable not only to a satellite communication system using geostationary earth orbit (GEO), medium earth orbit (MEO), or low earth orbit (LEO) satellites, but also to a high altitude platform station (HAPS).

[0127] The configurations shown in the above embodiments are examples of the contents of the present disclosure. The configurations of each embodiment can be combined with other known technologies. The configurations of each embodiment can be appropriately combined. A part of the configuration of each embodiment can be omitted or modified without departing from the gist of the present disclosure. [Explanation of symbols]

[0128] 1,1-k element arrangement, 2-a,2-b,2-c,2-d beam, 3 satellite communication system, 4,4A,4C,4D satellite repeater, 5 repeater control station, 6 satellite communication system control station, 7-1,7-2,7-m transmission beam, 10-1,10-2,10-nr receiving element, 11-1,11-2,11-nr LNA, 12-1,12-2,12-nr DCON, 13,13A,13D,13G DCH / DBF, 14-1,14-2,14-ns UCON, 15-1,15-2,15-ns TWTA, 16-1,16-2,16-ns transmitting element, 17,73 telecommunication control unit, 18 control antenna, 19,71 RF transmission / reception unit, 20, 20A, 20D, 72 Modem, 21-1, 21-2, 21-nr Received signal, 22-1, 22-2, 22-ns Transmitted signal, 23, 67, 77 Power adjustment coefficient calculation unit, 30-1, 30-2, 30-nr AD converter, 31-1, 31-2, 31-ns DA converter, 40, 40G Received DBF unit, 50, 50A, 50G Switch circuit, 60, 60B, 60E, 60F, 60G Transmitted DBF unit, 61 SerDes, 62-1, 62-2 DBF unit, 63-1 Distribution unit, 64-1-1, 64-1-2, 64-1-ns Excitation coefficient, 65, 65-1, 65-2, 65-ns, 65F Transmission power adjustment coefficient, 66, 66B, 66F-1 transmission power adjustment unit, 70 transmitting and receiving antenna, 74 command generation unit, 75 data transmitting and receiving unit, 76 excitation coefficient determination unit, 80 control circuit, 81 processor, 82 memory, 90 processing circuit, 100-1, 100-2, 101-1, 101-2, 102-1, 102-2, 103-1, 103-2 beam pattern, 111-1, 111-2, 112-1, 112-2, 113-1, 113-2 parameter setting area, 120 scheduler.

Claims

1. a satellite repeater including a plurality of transmitting elements and a power amplifier for amplifying a transmission power supplied to each of the plurality of transmitting elements, and forming a plurality of transmission beams by outputting a transmission signal from each of the plurality of transmitting elements; a repeater control station for controlling the satellite repeater, the repeater control station has a power adjustment coefficient calculation unit that calculates a transmission power allocation ratio, which is a ratio of the transmission power allocated to each of the plurality of transmitting elements to a target power, which is the output power when linearity of the output power of the power amplifier with respect to the input power to the power amplifier is maintained, and calculates a transmission power adjustment coefficient based on a maximum value of the transmission power allocation ratios calculated for each of the plurality of transmitting elements; A satellite communication system, wherein the satellite repeater has a transmission power adjustment unit that adjusts the transmission power of each of the plurality of transmitting elements based on the transmission power adjustment coefficient.

2. the satellite repeater forms a plurality of the transmission beams by outputting the transmission signal that has been subjected to digital beamforming processing from each of the plurality of transmission elements; 2. The satellite communication system according to claim 1, wherein the power adjustment coefficient calculation unit calculates the transmission power allocation rate based on an excitation coefficient used in the digital beamforming process and a frequency bandwidth allocated to each of the plurality of transmission beams.

3. the power adjustment coefficient calculation unit divides the plurality of transmitting elements into two or more transmitting element groups by grouping transmitting elements that contribute to the formation of the common transmission beam for the transmission beams formed using the common transmitting elements, and calculates the transmission power adjustment coefficient for each of the transmitting element groups based on the maximum value of the transmission power allocation rate for each of the transmitting element groups; 3. The satellite communication system according to claim 1, wherein the transmission power adjustment unit adjusts the transmission power based on the transmission power adjustment coefficient calculated for each of the groups of transmitting elements.

4. a satellite repeater including a plurality of transmitting elements and a power amplifier for amplifying a transmission power supplied to each of the plurality of transmitting elements, and forming a plurality of transmission beams by outputting a transmission signal from each of the plurality of transmitting elements; The satellite repeater comprises: a power adjustment coefficient calculation unit that calculates a power utilization rate, which is a ratio of power used by each of the plurality of transmitting elements to a target power, which is the output power when linearity of the output power of the power amplifier with respect to the input power to the power amplifier is maintained, and calculates a transmission power adjustment coefficient based on a maximum value of the power utilization rates calculated for each of the plurality of transmitting elements; a transmission power adjustment unit that adjusts the transmission power of each of the plurality of transmitting elements based on the transmission power adjustment coefficient.

5. the power adjustment coefficient calculation unit divides the plurality of transmitting elements into two or more transmitting element groups by grouping transmitting elements that contribute to the formation of the common transmitting beam for the transmitting beams formed using the common transmitting elements, and calculates the transmission power adjustment coefficient for each of the transmitting element groups based on the maximum value of the power utilization rate for each of the transmitting element groups; 5. The satellite communication system according to claim 4, wherein the transmission power adjustment unit adjusts the transmission power based on the transmission power adjustment coefficient calculated for each of the groups of transmitting elements.

6. the transmission power adjustment unit adjusts the transmission power of each of the plurality of transmitting elements by adjusting the transmission power for each of the transmission beams based on the transmission power adjustment coefficient, and excludes a portion of the plurality of transmission beams from being subjected to the adjustment of the transmission power; A satellite communication system according to any one of claims 1 to 5, characterized in that the power adjustment coefficient calculation unit calculates the transmission power adjustment coefficient by excluding from the calculation the power amount contributing to the formation of the transmission beam that is excluded from the adjustment.

7. the satellite repeater forms a plurality of the transmission beams by switching a beam pattern, which is a pattern of the plurality of the transmission beams, from among the plurality of the beam patterns in a time division manner; the power adjustment coefficient calculation unit calculates the transmission power adjustment coefficient corresponding to each of the plurality of beam patterns; 7. The satellite communication system according to claim 1, wherein the transmission power adjustment unit adjusts the transmission power by switching the transmission power adjustment coefficient in accordance with the switching of the beam pattern.

8. A repeater control station controls a satellite repeater having a plurality of transmitting elements and a power amplifier for amplifying a transmission power supplied to each of the plurality of transmitting elements to form a plurality of transmission beams by outputting a transmission signal from each of the plurality of transmitting elements, a power adjustment coefficient calculation unit that calculates a transmission power adjustment coefficient for adjusting the transmission power of each of the plurality of transmitting elements in the satellite repeater; The power adjustment coefficient calculation unit calculates a transmission power allocation rate, which is the ratio of the transmission power allocated to each of the multiple transmitting elements to a target power, which is the output power when the linearity of the output power of the power amplifier with respect to the input power to the power amplifier is maintained, and calculates the transmission power adjustment coefficient based on the maximum value of the transmission power allocation rates calculated for each of the multiple transmitting elements.

9. a plurality of transmitting elements each outputting a transmission signal for forming a plurality of transmission beams; a power amplifier that amplifies a transmission power supplied to each of the plurality of transmitting elements; a power adjustment coefficient calculation unit that calculates a power utilization rate, which is a ratio of power used by each of the plurality of transmitting elements to a target power, which is the output power when linearity of the output power of the power amplifier with respect to the input power to the power amplifier is maintained, and calculates a transmission power adjustment coefficient based on a maximum value of the power utilization rates calculated for each of the plurality of transmitting elements; a transmission power adjustment unit that adjusts the transmission power of each of the plurality of transmitting elements based on the transmission power adjustment coefficient.

10. A satellite communication system including a satellite repeater having a plurality of transmitting elements, a power amplifier for amplifying a transmission power supplied to each of the plurality of transmitting elements, and forming a plurality of transmission beams by outputting a transmission signal from each of the plurality of transmitting elements, and a repeater control station for controlling the satellite repeater, comprising: a transmission power determination method for determining the transmission power of each of the plurality of transmitting elements, determining a transmission power allocation rate, which is a ratio of the transmission power allocated to each of the plurality of transmitting elements to a target power, which is the output power when linearity of the output power of the power amplifier with respect to the input power to the power amplifier is maintained; calculating a transmission power adjustment coefficient based on a maximum value of the transmission power allocation ratios calculated for each of the plurality of transmitting elements; adjusting the transmission power of each of the plurality of transmitting elements based on the transmission power adjustment coefficient.

11. A method for determining the transmission power of each of a plurality of transmitting elements in a satellite communication system including a satellite repeater having a plurality of transmitting elements and a power amplifier for amplifying a transmission power supplied to each of the plurality of transmitting elements, and forming a plurality of transmission beams by outputting a transmission signal from each of the plurality of transmitting elements, comprising: determining a power utilization rate, which is a ratio of power used by each of the plurality of transmitting elements to a target power, which is the output power when linearity of the output power of the power amplifier with respect to the input power to the power amplifier is maintained; calculating a transmission power adjustment coefficient based on the maximum value of the power utilization rate calculated for each of the plurality of transmitting elements; adjusting the transmission power of each of the plurality of transmitting elements based on the transmission power adjustment coefficient.

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