Ground base station, communication relay device, remote control device, system, area control method, and program

Abstract

To provide a system capable of obtaining optimal antenna parameters in consideration of radio wave propagation characteristics of the actual environment in service area optimization by beamforming control and reducing the calculation amount for the service area optimization.SOLUTION: A system is configured to: pre-calculate and hold the radio wave propagation characteristics about each of a plurality of radio wave propagation paths between one or a plurality of transmission points assumed for a ground base station or an aerial relay-type communication relay device and a plurality of reception points assumed for the service area; estimate the positions of a plurality of terminal devices in the service area; optimize the antenna parameters for the service link antenna on the basis of the calculation results of the radio wace propagation characteristics of a plurality of radio wave propagation paths and the estimation results of the positions of the plurality of terminal devices; and apply the optimal values of the antenna parameters after optimization completion to the service link antenna.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to optimization of service areas through beamforming control in terrestrial mobile network systems and airborne platform systems. [Background technology]

[0002] Conventionally, there has been known an area optimization method for optimizing antenna parameters of a service link (e.g., the direction and width of a beam for forming a cell) so as to obtain a desired communication quality (e.g., throughput) throughout a service area (hereinafter simply referred to as an "area") formed on the ground by a communication relay device such as a high altitude platform station (HAPS) (also referred to as a "high altitude pseudo satellite") that can float in the air and remain in operation (see Patent Documents 1 to 4 and Non-Patent Documents 1 to 6).

[0003] For example, Non-Patent Document 1 discloses a method for area optimization assuming that user equipment (hereinafter also referred to as "UE") as terminal devices in an area is distributed uniformly. Non-Patent Document 2 discloses a method for performing optimization for each cell so as to obtain a desired communication quality (for example, throughput) throughout an area when the area is made up of multiple cells. Patent Document 4 discloses a method for estimating the positions of multiple terminal devices (UE) located within a service area, dividing the service area into multiple subareas each including multiple cells, and optimizing multiple types of antenna parameters of a service link antenna for each subarea based on the estimation results of the positions of the multiple terminal devices. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-161734 [Patent Document 2] Japanese Patent Publication No. 2022-161742 [Patent Document 3] Patent No. 7318047 [Patent Document 4] Patent No. 7108737 [Non-patent literature]

[0005] [Non-Patent Document 1] Y. Shibata, N. Kanazawa, M. Konishi, K. Hoshino, Y. Ohta and A. Nagate, "System Design of Gigabit HAPS Mobile Communications," in IEEE Access, vol. 8, pp. 157995-158007, 2020. [Non-patent document 2] Yohei Shibata, Wataru Takabatake, Kenji Hoshino, and Atsushi Nagate, "HAPS Dynamic Cell Control Algorithm Considering User Distribution in Multi-Cell Configurations," IEICE Technical Report, vol. 120, no. 322, RCS2020-185, pp. 170-175, January 2021. [Non-patent document 3] Shaoshuai Fan, Hui Tian1 and Cigdem Sengul ,"Self-optimization of coverage and capacity based on a fuzzy neural network with cooperative reinforcement learning", EURASIP Journal on Wireless Communications and Networking 2014. [Non-patent document 4] Rubayet Shafin, Hao Chen, Young Han Nam, Sooyoung Hur, Jeongho Park, Jianzhong (Charlie) Zhang, Jeffrey Reed, and Lingjia Liu "Self-Tuning Sectorization: Deep Reinforcement Learning Meets Broadcast Beam Optimization", IEEE Transactions on Wireless Communications, 2020. [Non-patent document 5] Eren Balevi and Jeffrey G. Andrews ,"A Novel Deep Reinforcement Learning Algorithm for Online Antenna Tuning", in Proc. IEEE Global Communications Conference (GLOBECOM), 2019. [Non-patent document 6] Yohei Shibata, Wataru Takabatake, Kenji Hoshino, Atsushi Nagate and Tomoaki Ohtsuki, "Two-Step Dynamic Cell Optimization Algorithm for HAPS Mobile Communications", IEEE Access, vol. 10, pp.68085-68098, 2022. Summary of the Invention [Problem to be solved by the invention]

[0006] To apply the above-mentioned area optimization to a real environment, optimization must take into account the radio wave propagation characteristics of the real environment. One possible area optimization method that takes into account the radio wave propagation characteristics of a real environment is optimization using a propagation simulator that simulates the radio wave propagation environment, such as topography and vegetation. In this area optimization control, optimal parameters are obtained by repeatedly updating parameters (antenna patterns) and calculating objective functions (e.g., communication capacity and coverage area) using the updated parameters that take into account the radio wave propagation characteristics of the real environment calculated by the propagation simulator. However, there is a problem in that the amount of calculation required to accurately calculate the radio wave propagation characteristics of the real environment using a propagation simulator (e.g., ray tracing) becomes enormous, making it practically difficult to achieve optimization by calculating radio wave propagation estimation every time the antenna parameters are updated. [Means for solving the problem]

[0007] A terrestrial base station according to one aspect of the present invention is a terrestrial base station that forms a cell for a terrestrial service area, and includes: calculation means for pre-calculating radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or a plurality of transmission points assumed for the terrestrial base station and a plurality of reception points assumed for the service area, storage means for storing calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths pre-calculated by the calculation means, position estimation means for estimating positions of a plurality of terminal devices within the service area, parameter optimization means for optimizing antenna parameters of a service link antenna based on the calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths and the estimation results of the positions of the plurality of terminal devices, and parameter application means for applying the optimal values ​​of the antenna parameters to the service link antenna after the optimization is completed.

[0008] According to another aspect of the present invention, there is provided a communication relay device of an airborne relay type that forms one or more cells toward a terrestrial or marine service area via a service link antenna of a relay communication station provided on an aircraft located in the air, and wirelessly communicates with a plurality of terminal devices located in the cells. The communication relay device includes: a calculation means that pre-calculates radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or more assumed transmission points for the relay communication station and a plurality of assumed reception points for the service area, a storage means that stores the calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths pre-calculated by the calculation means, a position estimation means that estimates the positions of a plurality of terminal devices within the service area, a parameter optimization means that optimizes antenna parameters of a service link antenna based on the calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths and the estimation results of the positions of the plurality of terminal devices, and a parameter application means that applies the optimized antenna parameters to the service link antenna after the optimization is completed.

[0009] According to yet another aspect of the present invention, there is provided a remote control device capable of communicating with an airborne relay-type communication relay device that forms one or more cells toward a terrestrial or marine service area via a service link antenna of a terrestrial base station that forms a cell toward a terrestrial service area or a relay communication station installed on an aircraft located in the air, and that wirelessly communicates with a plurality of terminal devices located in the cells. The remote control device includes: a calculation means that pre-calculates radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or more assumed transmission points of the terrestrial base station or the relay communication station and a plurality of assumed reception points for the service area, a storage means that stores the calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths pre-calculated by the calculation means, a position estimation means that estimates the positions of a plurality of terminal devices within the service area, a parameter optimization means that optimizes antenna parameters of a service link antenna based on the calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths and the estimation results of the positions of the plurality of terminal devices, and a parameter transmission means that transmits the optimized values ​​of the antenna parameters to the terrestrial base station or the communication relay device after the optimization is completed.

[0010] In the terrestrial base station, the communication relay device, and the remote control device, the position estimation means may estimate the positions of multiple terminal devices within the service area before pre-calculating the radio wave propagation characteristics, and the calculation means may pre-calculate the radio wave propagation characteristics for each of the multiple radio wave propagation paths using the estimated positions of the multiple terminal devices within the service area as the multiple receiving points.

[0011] In the terrestrial base station, the communication relay device, and the remote control device, the radio wave propagation characteristics that are pre-calculated and stored may be radio wave propagation characteristics that do not affect the antenna parameters, and the antenna parameters to be optimized may include multiple gains of the service link antenna in the direction of each of the multiple terminal devices.

[0012] In the terrestrial base station, the communication relay device, and the remote control device, the radio wave propagation characteristics that are pre-calculated and stored may include a plurality of angles viewed in the direction of each of the plurality of receiving points relative to the transmitting point of the service link antenna, and propagation losses of a plurality of radio wave propagation paths between the transmitting point of the service link antenna and the plurality of receiving points, and the antenna parameters to be optimized may include a plurality of gains of the service link antenna in the direction of each of the plurality of terminal devices.

[0013] In the terrestrial base station, the communication relay device, and the remote control device, the parameter optimization means may calculate a plurality of signal-to-noise ratios in a plurality of radio wave propagation paths from the service link antenna to the plurality of terminal devices for a plurality of candidate values ​​of the antenna parameter, and determine an optimal value of the antenna parameter to be applied to the service link antenna so as to maximize a median value of the plurality of signal-to-noise ratios calculated for the plurality of terminal devices.

[0014] In the terrestrial base station, the communication relay device, and the remote control device, the parameter optimization means may perform the parameter optimization using a genetic algorithm.

[0015] In the terrestrial base station, the communication relay device, and the remote control device, the parameter optimization means may repeatedly execute the parameter optimization a plurality of times (T times).

[0016] In the terrestrial base station, the communication relay device, and the remote control device, estimation of the positions of the multiple terminal devices, optimization of the antenna parameters, and application of the optimal values ​​of the antenna parameters to the service link antenna may be performed periodically or when a change in the distribution of the terminal devices in the service area becomes greater than a predetermined change.

[0017] In the communication relay device, the relay communication station may be connected to a mobile communication network via a feeder link to a terrestrial gateway station, and may include a base station processing unit that performs baseband processing.

[0018] In the communication relay device, the relay communication station may include a repeater unit that is connected to a base station device via a feeder link with a terrestrial gateway station and performs radio relay.

[0019] A system according to yet another aspect of the present invention includes any of the remote control devices described above and the terrestrial base station or the above.

[0020] A method according to yet another aspect of the present invention is an area control method for a service area consisting of cells formed from a terrestrial base station or an aerial repeating communication relay device toward the ground, the area control method including: pre-calculating radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or more assumed transmission points of the terrestrial base station or the aerial repeating communication relay device and a plurality of assumed reception points in the service area, retaining the pre-calculated calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths, estimating positions of a plurality of terminal devices within the service area, optimizing antenna parameters of a service link antenna based on the calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths and the estimated positions of the plurality of terminal devices, and applying the optimized values ​​of the antenna parameters to the service link antenna after the optimization is completed.

[0021] According to yet another aspect of the present invention, there is provided a program executed by a computer or processor provided in an aerial repeating communication relay device that forms one or more cells toward a terrestrial or marine service area via a service link antenna of a terrestrial base station that forms a cell toward a terrestrial service area or a relay communication station provided on an aircraft located in the air, and that wirelessly communicates with multiple terminal devices located in the cells. The program includes: program code for pre-calculating radio wave propagation characteristics for each of multiple radio wave propagation paths between one or more transmission points assumed for the terrestrial base station or the aerial repeating communication relay device and multiple reception points assumed for the service area, program code for retaining the pre-calculated calculation results of the radio wave propagation characteristics of the multiple radio wave propagation paths, program code for estimating positions of multiple terminal devices within the service area, program code for optimizing antenna parameters of a service link antenna based on the calculation results of the radio wave propagation characteristics of the multiple radio wave propagation paths and the estimation results of the positions of the multiple terminal devices, and program code for applying the optimized antenna parameters to the service link antenna after the optimization is completed.

[0022] A program according to yet another aspect of the present invention is a program executed by a computer or processor provided in a remote control device capable of communicating with a terrestrial base station or an aerial repeating communication relay device, the program including: program code for pre-calculating radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or more assumed transmission points for the terrestrial base station or the aerial repeating communication relay device and a plurality of assumed reception points for a service area; program code for storing the pre-calculated calculation results of the radio wave propagation characteristics for the plurality of radio wave propagation paths; program code for estimating positions of a plurality of terminal devices within the service area; program code for optimizing antenna parameters of a service link antenna based on the calculation results of the radio wave propagation characteristics for the plurality of radio wave propagation paths and the estimation results of the positions of the plurality of terminal devices; and program code for transmitting the optimized values ​​of the antenna parameters to the terrestrial base station or the communication relay device after the optimization is completed.

[0023] All or part of the program may include a trained model created by machine learning. [Effects of the Invention]

[0024] According to the present invention, in optimizing a service area by beamforming control, optimal antenna parameters can be obtained by taking into account the radio wave propagation characteristics of the actual environment, and the amount of calculation required for optimizing the service area can be reduced. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of the overall configuration of a communication system according to an embodiment. [Figure 2] Figure 2(a) is an explanatory diagram showing an example of the layout and size of cells in a service area consisting of seven cells before applying area optimization control for each cell, and Figure 2(b) is an explanatory diagram showing an example of the layout and size of cells after applying the area optimization control. [Figure 3]Fig. 3(a) is an explanatory diagram showing an example of the cell placement and size before application of area optimization control, as viewed from above in Fig. 2(a). Fig. 3(b) is an explanatory diagram showing an example of the cell placement and size after application of area optimization control, as viewed from above in Fig. 2(b). [Figure 4] FIG. 4 is an explanatory diagram showing an example of the antenna tilt angle, horizontal half width, and vertical half width as antenna parameters used in the area optimization control. [Figure 5] Fig. 5(a) is an explanatory diagram showing an example of a cell configuration of a service area consisting of seven cells with the central cell being small in size, and Fig. 5(b) is an explanatory diagram showing an example of a cell configuration of a service area consisting of seven cells with equal cell sizes. [Figure 6] FIG. 6 is a flowchart showing an example of general optimization control using a genetic algorithm according to a reference example. [Figure 7] 7(a) and 7(b) are explanatory diagrams showing an example of crossover in a genetic algorithm applicable to area optimization control, and an example of mutation in the same genetic algorithm. [Figure 8] Fig. 8(a) is an explanatory diagram showing an example of radio wave propagation in a line-of-sight environment between a terminal device located in a flat ground area and a terrestrial base station, and Fig. 8(b) is an explanatory diagram showing an example of radio wave propagation in a non-line-of-sight environment between a terminal device located in a mountainous area and a terrestrial base station. [Figure 9] FIG. 9 is a flowchart showing an example of area optimization control taking into consideration radio wave propagation characteristics according to a reference example. [Figure 10] FIG. 10 is a flowchart showing an example of area optimization control taking into consideration radio wave propagation characteristics in the communication system according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A system according to an embodiment of the present disclosure is a communication system in which a terrestrial base station or an airborne repeater (HAPS) serving as an airborne platform in a terrestrial mobile network system pre-calculates and stores radio wave propagation characteristics for each of multiple radio wave propagation paths between one or more assumed transmission points for the terrestrial base station or the airborne repeater (HAPS) and multiple assumed reception points for a service area, estimates the positions of multiple terminal devices within the service area, and performs area optimization control to optimize antenna parameters of a service link antenna based on the calculation results of the radio wave propagation characteristics of the multiple radio wave propagation paths and the estimated positions of the multiple terminal devices. This area optimization control enables the terrestrial base station, the airborne repeater (HAPS), or other such system to obtain optimal antenna parameters by taking into account the radio wave propagation characteristics of a real environment when optimizing the service area through beamforming control, thereby reducing the amount of calculation required for optimizing the service area.

[0027] 1 is an explanatory diagram showing an example of the overall configuration of a communication system according to an embodiment. Note that the communication system according to this embodiment is suitable for realizing a three-dimensional network for fifth-generation or later-generation mobile communications that supports simultaneous connection to a large number of terminal devices (hereinafter referred to as "UE") 61 and low latency. Furthermore, mobile communication standards applicable to the communication system, radio relay station, base station, repeater, and UE disclosed in this specification include fifth-generation mobile communication standards and standards for next-next-generation mobile communications after the fifth generation.

[0028] 1, the communication system includes, for example, a high altitude platform station (HAPS) (also called a "high altitude pseudo satellite" or "stratospheric platform") 10 as an airborne relay-type communication relay device (wireless relay device) constituting an airborne platform. The HAPS 10 is an airborne relay-type, airborne station-type, or airborne communication relay device that is located in an airspace at a predetermined altitude and forms a three-dimensional cell (three-dimensional area) in a cell formation target airspace at the predetermined altitude toward a target service area 20A.

[0029] HAPS10 is an air vehicle or floating body fuselage 100 that is controlled autonomously or externally to float or fly in a high-altitude airspace (floating airspace) at 100 km or less above ground or sea level, and is equipped with a relay communication station 110. The airspace in which HAPS10 is located may be, for example, stratospheric airspace with an altitude H of 18 km or more and 50 km or less. This airspace may also be an airspace with an altitude of 15 km or more and 25 km or less where meteorological conditions are relatively stable, and may particularly be an airspace with an altitude of approximately 20 km.

[0030] The cell formation target airspace, which is the target airspace in which HAPS10 will form a three-dimensional cell, may be an airspace within a predetermined altitude range (e.g., an altitude range of 50 m or more and 1000 m or less) located between the airspace in which HAPS10 is located and the cell formation area near the ground covered by a base station such as a conventional macrocell base station (e.g., an LTE eNodeB or a next-generation gNodeB).

[0031] The target airspace for cell formation may be above the sea, a river, or a lake. The 3D cell formed by HAPS 10 may also be formed to reach the ground or sea surface to enable communication with UE 61 located on the ground or sea.

[0032] The HAPS 10 communicates wirelessly with the UE 61 via a service link antenna (also referred to as an "SL antenna") 111 of a relay communication station 110 provided on an airframe 100, such as an air vehicle or a floating body, located in the sky. The HAPS 10 may be equipped with at least one of a battery and a solar power generation system and fly using electric power. The HAPS 10 may be a solar plane-type HAPS as shown in the figure, or an airship-type HAPS. The HAPS 10 provided with the relay communication station 110 may be an artificial satellite (e.g., a communication satellite), a balloon, or an unmanned aerial vehicle (UAV) such as a drone or unmanned aircraft systems (UAS). The HAPS 10 may be equipped with at least one of a battery and an engine as a power source. The UAV may be, for example, an unmanned aerial vehicle that flies using fuel or a drone that flies using a battery or the like.

[0033] The relay communication station 110 includes a service link antenna (SL antenna) 111 and a feeder link antenna (hereinafter also referred to as an "FL antenna") 112. The relay communication station 110 can perform service link (SL) communication with the UE 61 via the SL antenna 111. The SL antenna 111 is, for example, a beamforming-controllable array antenna that can control the direction and width of each of multiple beams that form multiple cells 20C(1) to 20C(7) in the target service area 20A. The areas through which the beams pass in the cell formation target airspace are the three-dimensional cells 20C(1) to 20C(7). Adjacent beams in the cell formation target airspace may partially overlap. Furthermore, multiple communication areas where the multiple cells 20C(1) to 20C(7) reach on the ground (or over the sea, etc.) are footprints 20F(1) to 20F(7).

[0034] In the illustrated example, seven cells 20C(1) to 20C(7) are formed via the SL antenna 111, but the number of cells 20C may be one, two to six, or eight or more.

[0035] The SL antenna 111 is, for example, a single or multiple array antennas in which multiple antenna elements are arranged two-dimensionally or three-dimensionally and capable of forming multiple beams toward the ground. The SL antenna 111 may also be a massive antenna in which many antenna elements are arranged two-dimensionally and capable of controlling beam directivity in the horizontal and vertical directions.

[0036] The relay communication station 110 can perform feeder link FL communication with a gateway device (also referred to as a "feeder station"; hereinafter referred to as a "GW station") 70 for HAPS installed on land (or sea, etc.) via the FL antenna 112. The FL antenna 112 is, for example, an array antenna whose directivity (direction of a directional beam) can be controlled. The FL antenna 112 is, for example, a single or multiple array antennas in which multiple antenna elements are arranged two-dimensionally or three-dimensionally. The FL antenna 112 may also be a massive antenna in which many antenna elements are arranged two-dimensionally and whose directivity can be controlled in the horizontal and vertical directions. The feeder link FL (F) in the figure is a forward link from the GW station 70 to the UE 61 via the HAPS 10, and the feeder link FL (R) is a reverse link from the UE 61 to the GW station 70 via the HAPS 10.

[0037] The relay communication station 110 mounted on the HAPS10 aircraft 100 may be a repeater-type relay communication station that relays transmitted and received signals without regenerating them, or may be a base station-type relay communication station that has a base station device that regenerates transmitted and received signals and re-modulates and relays the regenerated signals.

[0038] The repeater-type relay communication station 110 functions as a repeater slave corresponding to the repeater master constituted by the GW station 70, and is, for example, a wireless relay device (hereinafter also referred to as a "frequency converting repeater") that converts the frequency of a feeder link that is different from the frequency of a service link. In the downlink, the relay communication station 110 converts the frequency of the feeder link transmitted from the base station device 80 via the GW station 70 to the frequency of the service link, and transmits the converted frequency to the UE 61. On the other hand, in the uplink, the relay communication station 110 converts the frequency of the service link transmitted from the UE 61 to the frequency of the feeder link, and transmits the converted frequency to the base station device 80 via the GW station 70.

[0039] The repeater-type relay communication station 110 includes, for example, a repeater and a frequency converter. The repeater includes, for example, a low-noise amplifier that amplifies a service link SL reception signal received via the SL antenna 111, a power amplifier that amplifies a service link SL transmission signal transmitted via the SL antenna 111, etc. The frequency converter converts between the frequency of the service link SL and the frequency of the feeder link FL.

[0040] The base station type relay communication station 110 has a base station device and a frequency conversion device. The base station device has a baseband processing unit that processes baseband signals of the service link, a communication interface unit for communicating with the core network of the mobile communication network 90 via a backhaul line via the GW station 70, etc. The frequency conversion device converts between the frequency of the service link signal input / output to / from the base station device in the relay communication station 110 and the frequency of the feeder link signal transmitted / received via the FL antenna 112.

[0041] In the following embodiment, a case will be mainly described in which the relay communication station 110 mounted on the airframe 100 of the HAPS 10 is a repeater-type relay communication station (repeater slave station).

[0042] UE (User Equipment) 61 is a terminal device used by a user on land or at sea. UE 61 is, for example, a mobile phone, a smartphone, a portable personal computer with mobile communication capabilities, etc., and is also called a mobile terminal, a mobile station, a mobile device, or a portable communication terminal. UE 61 may be a modular mobile station incorporated in a moving object such as a vehicle such as an automobile, or a drone, which is an aircraft such as a small remotely controlled helicopter, or may be a terminal device for an IoT (Internet of Things) device.

[0043] HAPS10 may autonomously control its own levitation (flight) and the processing and control at the relay communication station 110 by executing a control program using a control unit configured with an internally embedded computer or processor. For example, HAPS10 may autonomously perform area optimization control, which will be described later. HAPS10 may also acquire its own current location information (e.g., GNSS (Global Navigation Satellite System) location information such as GPS location information), pre-stored location control information (e.g., flight schedule information), and location information of other HAPSs located in the vicinity, and autonomously control its levitation (flight) and the processing and control at the relay communication station 110 based on this information.

[0044] The position and attitude information of the HAPS 10 may be acquired based on the output of a GPS receiver, a gyro sensor, an acceleration sensor, an inertial sensor, etc., incorporated into the HAPS 10. For example, the position and attitude information of the HAPS 10 may be acquired based on the output of a GNSS-inertial navigation system (GNSS / INS) that combines a GNSS system and an inertial measurement unit (IMU) incorporated into the HAPS 10.

[0045] The levitation (flight) of HAPS 10 and the processing and control at relay communication station 110 may be controlled by a remote control device 95 installed in a communication center or the like of mobile communication network 90. ​​Remote control device 95 may be configured, for example, as a computer device such as a PC, a server, or the like. HAPS 10 may incorporate a control communication terminal device (e.g., a mobile communication module) so that it can receive control information from the remote control device 95 and transmit various information such as monitoring information to the remote control device 95, and may be assigned terminal identification information (e.g., IP address, telephone number, etc.) so that it can be identified by the remote control device 95. The MAC address of the communication interface may be used to identify the control communication terminal device.

[0046] The remote control device 95 may cooperate with the HAPS 10 and the terrestrial base station 30 to perform area optimization control, which will be described later.

[0047] The HAPS10 may also transmit monitoring information, such as information related to the flight (flight) of itself or surrounding HAPS and processing at the relay communication station 110, position information of the HAPS10, information related to the status of the HAPS10, and observation data acquired by various sensors, to a predetermined destination such as the remote control device 95. The control information may include target flight route information for the HAPS. The monitoring information may include at least one of the following information: the current position of the HAPS10, flight route history information, airspeed, ground speed and thrust direction, wind speed and direction of air currents around the HAPS10, and atmospheric pressure and temperature around the HAPS10.

[0048] The duplexing method for the uplink and downlink of the wireless communication between the relay communication station 110 and the UE 61 is not limited to a specific method and may be, for example, a time division duplex (TDD) method or a frequency division duplex (FDD) method. The access method for the wireless communication between the relay communication station 110 and the UE 61 is not limited to a specific method and may be, for example, a frequency division multiple access (FDMA) method, a time division multiple access (TDMA) method, a code division multiple access (CDMA) method, or an orthogonal frequency division multiple access (OFDMA) method. The wireless communication may also use a multi-input and multi-output (MIMO) technology that has functions such as diversity coding, transmit beamforming, and spatial division multiplexing (SDM) and can increase the transmission capacity per unit frequency by simultaneously using multiple antennas for both transmission and reception. Furthermore, the MIMO technology may be SU-MIMO (Single-User MIMO) technology in which one base station transmits multiple signals to one UE at the same time and frequency, or MU-MIMO (Multi-User MIMO) technology in which one base station transmits signals to multiple different UEs at the same time and frequency, or multiple different base stations transmit signals to one UE at the same time and frequency.

[0049] In the communication system configured as described above, for example, a signal from a base station device 80 is relayed by the GW station 70 and the HAPS 10, enabling communication services to be provided to UEs (mobile terminals) 61 on the ground. In particular, according to the communication system of this embodiment, the HAPS 10, an aerial relay-type communication relay device that functions as an aerial platform, can provide ultra-wide area mobile communication services directly to UEs (mobile terminals) 61 on the ground from the stratosphere at altitudes of 18 km or more and 50 km or less (particularly around 20 km). Furthermore, an aerial platform consisting of the HAPS 10 is attracting attention as a new form of communication suitable for use in the event of a large-scale disaster or the like.

[0050] In the communication system of this embodiment, area optimization is performed to optimize the antenna parameters of the SL antenna 111 so as to obtain a desired communication quality (e.g., throughput) throughout the entire service area 20A, which is made up of multiple cells 20C(1) to 20C(7) formed toward the ground by an airborne platform such as HAPS 10. For example, in an airborne platform such as HAPS 10 that covers the service area 20A with multiple cells 20C(1) to 20C(7), area optimization control is performed to optimize the beam direction and width of each cell according to the population distribution (or user distribution, UE distribution, etc.).

[0051] In the area optimization control, for example, in a multi-cell configuration in which a service area 20A is made up of multiple cells 20C(1) to 20C(7), the placement of each cell is optimized so as to maximize the communication capacity and coverage area of ​​the entire service area according to population distribution and traffic distribution. As an optimization control algorithm, for example, a genetic algorithm (GA) can be used (see Patent Document 4 mentioned above).

[0052] For example, as shown in FIGS. 2(a) and 3(a), if multiple cells 20C(1) to 20C(7) of the same size are uniformly distributed in a service area 20A without applying area optimization control, coverage and communication capacity may be reduced in the user (UE) dense area located to the left of the service area 20A in the figures. On the other hand, in FIGS. 2(b) and 3(b), area optimization control is applied, which optimizes the beam direction and width for each of the multiple cells 20C(1) to 20C(7) based on big data such as the population distribution in the service area 20A. By applying area optimization control in this way, the number of cells covering the user (UE) dense area located to the left of the service area 20A can be increased to intensively cover the user (UE) dense area, thereby suppressing a decrease in communication capacity in the user (UE) dense area. This maximizes coverage and communication capacity in the service area 20A.

[0053] In area optimization control, for example, in area optimization of an area consisting of multiple (N) cells, the following four types of antenna parameters A to D are defined and used as multiple types of antenna parameters for any i-th cell i within the area, and a total of 4N antenna parameters are optimized. A. Tilt angle θ tilt,i B. Vertical half width θ 3dB,i C. Horizontal half width φ 3dB,i D. Cell horizontal direction ω i

[0054] As shown in Figure 4, the tilt angle θ tilt,i is the angle from the horizontal direction H of the vector Vc directed from the SL antenna 111 of the HAPS 10 to the center of the i-th cell 20C(i) of interest. 3dB,i is the vertical plane P containing the vector Vc pointing to the center of the i-th cell 20C(i). V The horizontal half-width φ is the angular width between the two points where the beam gain is reduced by 3 dB from the maximum gain at the center of the main beam. 3dB,iis the horizontal plane P containing the vector Vc pointing to the center of the i-th cell 20C(i). H The angular width between two points where the beam gain is reduced by 3 dB from the maximum gain at the center of the main beam.

[0055] Also, the horizontal direction of the i-th cell, ω i is the angle of the direction passing through the center of the target cell from a predetermined reference horizontal direction Hs on a horizontal plane including the position of the SL antenna 111 of the HAPS 10 as a reference point.

[0056] The objective function in area optimization control can be, for example, a function corresponding to 50% of the ideal throughput for multiple terminal devices (users) in the service area consisting of multiple cells. The ideal throughput in the service area can be calculated using, for example, the following equation (1).

number

[0057] Here, the above formula (1) indicates the throughput for the u-th terminal device (user) in the c-th cell within the service area. In the formula, "c" is the cell number, "u" is the user number, and "γ c,u " is the downlink SINR (signal to noise ratio), and "N avg " is the total number of terminal devices (total number of users) in the service area divided by the number of cells, and "N c " is the number of terminal devices (users) in the cth cell.

[0058] In the above formula (1),

number

number

number

number

[0059] Constraints in area optimization control can be set, for example, so that 99% of terminal devices (users) within the service area 20A satisfy the conditions in Table 1 below (see Non-Patent Document 6 mentioned above). [Table 1]

[0060] Figure 6 is a flowchart showing an example of general optimization control using a genetic algorithm (GA) that can be applied to area optimization control. A genetic algorithm (GA) is an algorithm created by imitating the evolutionary process of living organisms, and performs optimization by repeatedly selecting, crossing over, and mutating "genes," making it possible to discover excellent solutions within a practical time frame.

[0061] In FIG. 6, for example, the initial population corresponds to multiple sets of antenna parameters for a terrestrial base station or an airborne repeater (HAPS), each individual (parent, child) corresponds to a communication system for the entire service area, and genes correspond to antenna parameters. In FIG. 6, first, an initial population consisting of multiple sets of individuals is randomly generated (S101). Next, in each generation, the genetic scores of the individuals are evaluated using an "objective function" (S102), parents are selected (S103), and genetic crossover (see FIG. 7(a)) and mutation (see FIG. 7(b)) are applied (S104), and the next generation of individuals is determined (S105). Here, mutation can avoid local optima. These steps from S102 to S105 are repeated until a predetermined number of iterations (the number of generations for convergence determination) is reached (S102 to S106), and superior genes are inherited to maximize the objective function (the genetic scores of the individuals).

[0062] By applying the genetic algorithm (GA) to area optimization control and repeating the change and evaluation of antenna parameters, it is possible to approach the optimal solution for antenna parameters.

[0063] In order to reflect the above-mentioned area optimization technology in the actual environment of the service area 20A of the communication system and obtain improvements in communication capacity (throughput) and coverage, optimization is required that takes into consideration in advance the radio wave propagation characteristics in the actual environment, which is affected by diffraction and reflection caused by obstacles 40 such as terrain, buildings, and vegetation, as shown in Fig. 8(b), rather than a simple model such as a flat earth as shown in Fig. 8(a). One possible method for taking into consideration the radio wave propagation characteristics in the actual environment is to consider radio wave propagation in the actual environment in an evaluation after changing parameters.

[0064] 9 is a flowchart showing an example of area optimization control that takes into account radio wave propagation characteristics according to a reference example. In FIG. 9, initial antenna parameters are set (S201), and then area evaluation (S202) when the antenna parameters are applied, antenna parameter change (S203), and convergence determination (S204) are repeatedly performed to obtain an optimal solution for the antenna parameters. In the area evaluation (S202) of this area optimization control, a propagation simulator is used (S205) to simulate a real environment that is affected by diffraction and reflection from obstacles 40 such as topography, buildings, and vegetation, and estimate radio wave propagation characteristics using a ray tracing method or the like. An objective function (communication capacity and coverage size) is calculated taking into account the radio wave propagation characteristics of the real environment estimated by the propagation simulator.

[0065] However, estimating radio wave propagation characteristics in a real environment using a propagation simulator (S205) (using a ray tracing method, etc.) requires a long calculation time. In particular, as shown in Figure 8(b) in a real environment, the calculation time becomes enormous when the number of reflections and diffractions of radio waves increases. Furthermore, estimating radio wave propagation characteristics in a real environment with high accuracy requires an enormous amount of calculation. Therefore, it is practically difficult to perform optimization by calculating an objective function (communication capacity or coverage area) that involves estimating radio wave propagation characteristics every time the antenna parameters are updated.

[0066] Therefore, in this embodiment, radio wave propagation characteristics are calculated in advance for each of a plurality of radio wave propagation paths between one or more assumed transmission points for the airborne repeating communication relay device (HAPS) 10 (see FIGS. 1 to 4) and the terrestrial base station 30 (see FIGS. 8(a) and 8(b)) and a plurality of assumed reception points for the service area 20A, and are stored. Then, the positions of a plurality of user equipment (UE) 61 within the service area 20A are estimated, and the antenna parameters of the service link antennas 111, 31 are optimized based on the calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths and the estimation results of the positions of the plurality of user equipment (UE) 61.

[0067] Here, before pre-calculating the radio wave propagation characteristics, the positions of multiple user equipment (UE) 61 within the service area 20A may be estimated, and the estimated positions of the multiple user equipment (UE) 61 within the service area 20A may be used as the multiple reception points to pre-calculate and store the radio wave propagation characteristics for each of the multiple radio wave propagation paths. In this case, the radio wave propagation characteristics may be recalculated for some or all of the multiple radio wave propagation paths every time one or more user equipment (UE) 61 within the service area 20A moves. In particular, when one or some user equipment (UE) 61 within the service area 20A moves, the radio wave propagation characteristics may be recalculated only for one or some of the user equipment (UE) 61 that has moved, thereby improving the efficiency of the calculation. Furthermore, when calculating the radio wave propagation characteristics of the radio wave propagation paths using the estimated positions of the user equipment (UE) 61 within the service area 20A as reception points, the amount of calculation can be reduced compared to conventional general calculations of radio wave propagation characteristics in which the transmission antenna gain at the transmission point is set in advance.

[0068] Furthermore, for example, the center points of a plurality of small-sized sections that are set by dividing the service area 20A into a mesh pattern may be used as the plurality of receiving points, and the radio wave propagation characteristics may be calculated in advance for each of the plurality of radio wave propagation paths.

[0069] Furthermore, in a system including an aerial repeater type communication repeater (HAPS) 10 (see FIGS. 1 to 4), the area optimization control of this embodiment may be combined with footprint fixation control (see patent application filed by the present applicant (Japanese Patent Application No. 2023-177048)). In footprint fixation control, the direction of the beam formed by the service link antenna (SL antenna 111) or the directivity direction of the service link antenna (SL antenna 111) is controlled so as to fix the position of the footprint of the cell in the service area 20A, based on information on at least one of the position and attitude of the aerial repeater type communication repeater (HAPS) 10. By combining this footprint fixation control, area optimization control can be performed assuming that the aerial repeater type communication repeater (HAPS) 10 is stopped at a fixed point.

[0070] The radio wave propagation characteristics calculated and stored in advance may be radio wave propagation characteristics that do not affect antenna parameters. For example, the radio wave propagation characteristics calculated and stored in advance may include a plurality of angles viewed in the direction of each of a plurality of reception points relative to the transmission point of the service link antenna 111, 31, and propagation losses of a plurality of radio wave propagation paths between the transmission point of the service link antenna and the plurality of reception points. Furthermore, the antenna parameters to be optimized may include a plurality of gains of the service link antenna 111, 31 in the direction of each of a plurality of user equipments (UEs) 61.

[0071] FIG. 10 is a flowchart showing an example of area optimization control that takes into account radio wave propagation characteristics in a communication system according to an embodiment. The area optimization control of FIG. 10 can be applied to both an airborne repeater-type communication repeater (HAPS) 10 and a terrestrial base station 30. In FIG. 10, initial antenna parameters are set (S301). Then, for each of a plurality of radio wave propagation paths (paths) between one or more pre-estimated transmission points and a plurality of pre-estimated reception points in the service area 20A, the angle and propagation loss of each path are pre-calculated and stored (S302). Next, based on the pre-calculated and stored calculated values ​​of the angle and propagation loss of each path and the estimated positions of a plurality of user equipments (UEs) 61 within the service area 20A, the service area (communication area) 20A when the antenna parameters are applied is evaluated (S303). For example, the service area (communication area) 20A is evaluated by calculating at least one of the communication capacity and coverage size of the service area (communication area) 20A. Then, the antenna parameters of the service link antennas 111 and 31 are repeatedly changed and the service area (communication area) 20A is repeatedly evaluated (S303 to S304) until the evaluation result of the service area (communication area) 20A satisfies a predetermined convergence condition, thereby obtaining an optimal solution for the antenna parameters.

[0072] After the optimization is completed, the final updated values ​​of the antenna parameters of each cell in the service area 20A are applied as the control setting values ​​of the antenna 31 of the terrestrial base station 30 and the SL antenna 111 at the relay communication station 110 of the HAPS (Air Platform) 10.

[0073] The area optimization control illustrated in FIG. 10 may be performed periodically (for example, periodically every hour or every two hours), or may be performed whenever there is a significant change in the UE distribution within the service area 20A (for example, when the change in the number of UEs within a specified monitoring area exceeds a specified threshold).

[0074] By executing the area optimization control, it is possible to obtain a desired communication quality (for example, throughput) throughout the entire service area 20A made up of a plurality of cells 20C(1) to 20C(7).

[0075] The optimum values ​​of the antenna parameters may be determined by calculating the signal-to-noise ratio (SNR) for each radio wave propagation path as shown below. Here, to simplify the radio wave propagation model, N radio wave propagation paths are formed between one transmitting point of the service link antennas 111, 31 and multiple (N) receiving points, and only one path is considered for transmission and reception. The antenna parameters subject to area optimization control are the antenna gain (beam direction and beam width) for each path of the service link antennas 111, 31.

[0076] In the comparative reference example on flat ground shown in FIG. 8(a), the signal-to-noise ratios (SNR(1) to SNR(N)) in each radio wave propagation path are expressed by the following equation (2).

number

[0077] where Pt is the transmission power, G(θ(n)) is the antenna gain at angle θ(n) in the direction of the terminal device (user) 61(n) (θ is a value uniquely determined by the relative positions of the interfering station and the terminal device (user)), Ploss is the free space propagation loss for each path, Gr is the receiving antenna gain, and Pn is the noise power on the receiving side. For example, when determining the antenna gain G(θ) that maximizes the median of SNR(1) to SNR(N) in equation (2) above (maximizing coverage), the antenna gain (beam direction and beam width) for each path of the service link antennas 111 and 31 can be optimized by changing the beam direction, beam width, etc., i.e., changing the antenna gain G(θ) in the direction of the terminal device (user), and repeating the above SNR calculation. On a flat ground, calculating the angle θ and the free space propagation loss Ploss takes almost no time, so there is no problem in repeating the calculation each time area optimization is performed (each time the antenna parameters are changed).

[0078] On the other hand, when considering propagation loss in an environment affected by diffraction and reflection from obstacles 40 such as terrain, buildings, and vegetation as shown in FIG. 8(b), it is necessary to calculate the free space propagation loss Ploss' and the angle θ' (tilt angle θ' and azimuth angle φ' in a three-dimensional context). When multiple paths are taken into consideration, it is necessary to calculate the propagation losses (Ploss'(1) to Ploss'(N)) for N paths and their corresponding angles (θ'(1) to θ'(N)). In other words, every time the antenna parameters are changed, it is necessary to calculate the angles θ'(1) to θ'(N), the propagation losses Ploss'(1) to Ploss'(N), and the noise power Pn on the receiving side in the following equation (3). This results in an enormous amount of calculation.

number

[0079] In the area optimization control of this embodiment, the propagation loss Ploss' and angle θ' in the above equation (3) are calculated in advance and stored in a storage unit (storage means) such as a memory, and the calculation is repeated while changing G(θ'), thereby reducing the amount of calculation and enabling area optimization. When multiple (N) paths are taken into consideration, the propagation losses (Ploss'(1) to Ploss'(N)) for N paths and their corresponding angles (θ'(1) to θ'(N)) are calculated in advance and stored.

[0080] In this embodiment, the HAPS10 also functions as the following means A1 to A5 by the control unit, which is configured by an internally incorporated computer or processor, executing a control program. A1. A calculation means for pre-calculating radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or a plurality of assumed transmission points for the relay communication station 110 and a plurality of assumed reception points for the service area 20A. A2.Means for storing the calculation results of radio wave propagation characteristics of multiple pre-calculated radio wave propagation paths A3. Position estimation means for estimating the positions of a plurality of terminal devices 61(1) to 61(N) within the service area 20A A4. Parameter optimization means for optimizing the antenna parameters of the service link antenna 111 based on the calculation results of the radio wave propagation characteristics of a plurality of radio wave propagation paths and the estimation results of the positions of a plurality of terminal devices 61(1) to 61(N). A5. Parameter application means for applying the optimal values ​​of the antenna parameters after the optimization is completed to the service link antenna 111

[0081] In this embodiment, the terrestrial base station 30 also functions as the following means B1 to B5 by a control unit configured by an internally incorporated computer or processor executing a control program. B1. A calculation means for pre-calculating radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or a plurality of transmission points assumed for the terrestrial base station 30 and a plurality of reception points assumed for the service area 20A. B2.Means for storing the calculation results of the radio wave propagation characteristics of multiple pre-calculated radio wave propagation paths B3, a position estimation means for estimating the positions of a plurality of terminal devices 61(1) to 61(N) within the service area 20A; B4. Parameter optimization means for optimizing antenna parameters of the service link antenna 31 based on the calculation results of the radio wave propagation characteristics of a plurality of radio wave propagation paths and the estimation results of the positions of a plurality of terminal devices 61(1) to 61(N). B5. Parameter application means for applying the optimal values ​​of the antenna parameters after the optimization is completed to the service link antenna 31

[0082] The remote control device 95 also functions as the following means C1 to C5 by a control unit configured by an internally incorporated computer or processor executing a control program. C1. A calculation means for pre-calculating radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or a plurality of assumed transmission points of the terrestrial base station 30 or the relay communication station 110 of the airborne relay type communication repeater (HAPS) 10 and a plurality of assumed reception points of the service area 20A. C2. A means for storing the calculation results of the radio wave propagation characteristics of multiple pre-calculated radio wave propagation paths C3. Position estimation means for estimating the positions of a plurality of terminal devices 61(1) to 61(N) within the service area 20A C4. Parameter optimization means for optimizing antenna parameters of the service link antennas 31 and 111 based on the calculation results of the radio wave propagation characteristics of a plurality of radio wave propagation paths and the estimation results of the positions of a plurality of terminal devices 61(1) to 61(N). C5. Parameter transmission means for transmitting the optimal values ​​of the antenna parameters after the optimization is completed to the terrestrial base station 30 or the communication relay device (HAPS) 10

[0083] As described above, according to this embodiment, in optimizing the service area 20A by beamforming control in the terrestrial base station 30 and the relay communication station 110 of the airborne repeating communication relay device (HAPS) 10, optimal antenna parameters can be obtained by taking into account the radio wave propagation characteristics of the actual environment, and the amount of calculation required to optimize the service area 20A can be reduced.

[0084] Furthermore, this invention can build a new communications platform for use in large-scale disasters, etc., that can provide ultra-wide area mobile communications services to terrestrial terminal devices from the stratosphere at an altitude of about 20 km, thereby contributing to the achievement of Goal 9 of the Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0085] The process steps described herein and the components of the relay communication station, feeder station, gateway station, remote control device, server, terminal device (user equipment, mobile station, communication terminal), base station, and base station device of a communication relay device such as a HAPS can be implemented by various means. For example, these processes and components may be implemented by hardware, firmware, software, or a combination thereof.

[0086] For hardware implementation, means such as processing units used to realize the above steps and components in an entity (e.g., a wireless relay station, a feeder station, a gateway station, a base station, a base station device, a wireless relay station device, a terminal device (user device, mobile station, communication terminal), a management device, a monitoring device, a remote control device, a server, a hard disk drive device, or an optical disk drive device) may be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, computers, or combinations thereof.

[0087] Additionally, for firmware and / or software implementations, the means, such as processing units, used to implement the components may be implemented with programs (e.g., code, such as procedures, functions, modules, instructions, etc.) that perform the functions described herein. In general, any computer / processor-readable medium tangibly embodying firmware and / or software code may be used to implement the means, such as processing units, used to implement the steps and components described herein. For example, the firmware and / or software code may be stored in a memory and executed by a computer or processor, such as in a controller. The memory may be implemented within the computer or processor or external to the processor. Furthermore, the firmware and / or software code may be stored in a computer- or processor-readable medium, such as random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), flash memory, floppy disk, compact disk (CD), digital versatile disk (DVD), magnetic or optical data storage device, etc. The code may be executed by one or more computers or processors and may cause the computers or processors to perform certain aspects of the functionality described herein.

[0088] The medium may be a non-transitory recording medium. The program code may be in any format as long as it can be read and executed by a computer, processor, or other device or machine. For example, the program code may be in any of source code, object code, and binary code, or may be a mixture of two or more of these codes.

[0089] Moreover, the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. [Explanation of symbols]

[0090] 10: HAPS (Airborne Repeater System) 20A: Service area 20C: Cell 20F: Footprint 30: Terrestrial base station 31: Antenna 40: Obstacle 61: UE (Terminal Equipment) 70: Golden Week Station 71: Radio relay device 80:Base station equipment 90: Mobile communication network (core network) 95: Remote control device 100: Aircraft 110: Relay communication station 111: Service link antenna (SL antenna)

Claims

1. A terrestrial base station that forms a cell for a terrestrial service area, a calculation means for calculating in advance radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or a plurality of transmission points assumed for the terrestrial base station and a plurality of reception points assumed for the service area; a storage means for storing the calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths calculated in advance by the calculation means; a location estimation means for estimating the locations of a plurality of terminal devices within the service area; parameter optimization means for optimizing antenna parameters of a service link antenna based on calculation results of radio wave propagation characteristics of the plurality of radio wave propagation paths and estimation results of the positions of the plurality of terminal devices; a parameter application means for applying the optimal values ​​of the antenna parameters after the optimization is completed to the service link antenna; A terrestrial base station comprising:

2. 2. The terrestrial base station of claim 1, the location estimation means estimates locations of a plurality of terminal devices within the service area before pre-calculating the radio wave propagation characteristics; the calculation means pre-calculates the radio wave propagation characteristics for each of the plurality of radio wave propagation paths, using the estimated positions of the plurality of terminal devices within the service area as the plurality of reception points. A terrestrial base station characterized by:

3. 2. The terrestrial base station of claim 1, the radio wave propagation characteristics that are pre-calculated and stored are radio wave propagation characteristics that do not affect the antenna parameters, the antenna parameters to be optimized include a plurality of gains of the service link antenna in directions of the plurality of terminal devices, A terrestrial base station characterized by:

4. 2. The terrestrial base station of claim 1, the pre-calculated and stored radio wave propagation characteristics include a plurality of angles from a transmission point of the service link antenna to a direction of each of the plurality of reception points, and propagation losses of a plurality of radio wave propagation paths between the transmission point of the service link antenna and the plurality of reception points; the antenna parameters to be optimized include a plurality of gains of the service link antenna in directions of the plurality of terminal devices, A terrestrial base station characterized by:

5. 5. The terrestrial base station according to claim 1, The parameter optimization means calculating a plurality of signal-to-noise ratios in a plurality of radio wave propagation paths from the service link antenna to the plurality of terminal devices for a plurality of candidate values ​​of the antenna parameter; determining optimal values ​​of the antenna parameters to be applied to the service link antenna so as to maximize the median of the plurality of signal-to-noise ratios calculated for the plurality of terminal devices; A terrestrial base station characterized by:

6. An airborne relay type communication relay device that forms one or more cells toward a ground or sea service area via a service link antenna of a relay communication station installed on an aircraft located in the air, and wirelessly communicates with multiple terminal devices located in the cells, a calculation means for calculating in advance radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or a plurality of transmission points assumed for the relay communication station and a plurality of reception points assumed for the service area; a storage means for storing the calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths calculated in advance by the calculation means; a location estimation means for estimating the locations of a plurality of terminal devices within the service area; parameter optimization means for optimizing antenna parameters of a service link antenna based on calculation results of radio wave propagation characteristics of the plurality of radio wave propagation paths and estimation results of the positions of the plurality of terminal devices; a parameter application means for applying the optimal values ​​of the antenna parameters after the optimization is completed to the service link antenna; A communication relay device comprising:

7. 7. The communication relay device according to claim 6, the location estimation means estimates locations of a plurality of terminal devices within the service area before pre-calculating the radio wave propagation characteristics; the calculation means pre-calculates the radio wave propagation characteristics for each of the plurality of radio wave propagation paths, using the estimated positions of the plurality of terminal devices within the service area as the plurality of reception points. A communication relay device characterized by:

8. 7. The communication relay device according to claim 6, the radio wave propagation characteristics that are pre-calculated and stored are radio wave propagation characteristics that do not affect the antenna parameters, the antenna parameters to be optimized include a plurality of gains of the service link antenna in directions of the plurality of terminal devices, A communication relay device characterized by:

9. 7. The communication relay device according to claim 6, the pre-calculated and stored radio wave propagation characteristics include a plurality of angles from a transmission point of the service link antenna to a direction of each of the plurality of reception points, and propagation losses of a plurality of radio wave propagation paths between the transmission point of the service link antenna and the plurality of reception points; the antenna parameters to be optimized include a plurality of gains of the service link antenna in directions of the plurality of terminal devices, A communication relay device characterized by:

10. 9. The communication relay device according to claim 6, The parameter optimization means calculating a plurality of signal-to-noise ratios in a plurality of radio wave propagation paths from the service link antenna to the plurality of terminal devices for a plurality of candidate values ​​of the antenna parameter; determining optimal values ​​of the antenna parameters to be applied to the service link antenna so as to maximize the median of the plurality of signal-to-noise ratios calculated for the plurality of terminal devices; A communication relay device characterized by:

11. A remote control device capable of communicating with an airborne relay type communication relay device that forms one or more cells toward a ground or marine service area via a service link antenna of a terrestrial base station that forms a cell toward a ground service area or a relay communication station installed on an aircraft located in the air, and wirelessly communicates with a plurality of terminal devices located in the cell, a calculation means for calculating in advance radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or a plurality of transmission points assumed for the terrestrial base station or the relay communication station and a plurality of reception points assumed for the service area; a storage means for storing the calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths calculated in advance by the calculation means; a location estimation means for estimating the locations of a plurality of terminal devices within the service area; parameter optimization means for optimizing antenna parameters of a service link antenna based on calculation results of radio wave propagation characteristics of the plurality of radio wave propagation paths and estimation results of the positions of the plurality of terminal devices; a parameter transmitting means for transmitting the optimal values ​​of the antenna parameters after the optimization is completed to the terrestrial base station or the communication relay device; A remote control device comprising:

12. 12. The remote control device of claim 11, the location estimation means estimates locations of a plurality of terminal devices within the service area before pre-calculating the radio wave propagation characteristics; the calculation means pre-calculates the radio wave propagation characteristics for each of the plurality of radio wave propagation paths, using the estimated positions of the plurality of terminal devices within the service area as the plurality of reception points. A remote control device characterized by:

13. 12. The remote control device of claim 11, the radio wave propagation characteristics include a plurality of angles from a transmission point of the service link antenna to a direction of each of the plurality of reception points, and propagation losses of a plurality of radio wave propagation paths between the transmission point of the service link antenna and the plurality of reception points; the antenna parameters to be optimized include a plurality of gains of the service link antenna in directions of the plurality of terminal devices, A remote control device characterized by:

14. 14. The remote control device according to claim 11, The parameter optimization means calculating a plurality of signal-to-noise ratios in a plurality of radio wave propagation paths from the service link antenna to the plurality of terminal devices for a plurality of candidate values ​​of the antenna parameter; determining optimal values ​​of the antenna parameters to be applied to the service link antenna so as to maximize the median of the plurality of signal-to-noise ratios calculated for the plurality of terminal devices; A remote control device characterized by:

15. A system comprising the remote control device according to any one of claims 11 to 13 and the terrestrial base station or the aerial relay type communication relay device.

16. An area control method for a service area consisting of cells formed from a terrestrial base station or an aerial relay type communication relay device toward the ground, comprising: Pre-calculating radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or a plurality of transmission points assumed for the terrestrial base station or the aerial relay type communication relay device and a plurality of reception points assumed for the service area; storing the pre-calculated calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths; estimating the locations of a plurality of terminal devices within the service area; optimizing antenna parameters of a service link antenna based on calculation results of radio wave propagation characteristics of the plurality of radio wave propagation paths and estimation results of positions of the plurality of terminal devices; applying the optimized values ​​of the antenna parameters to the service link antenna after the optimization is completed; An area control method comprising:

17. A program executed by a computer or processor provided in an airborne relay type communication relay device that forms one or more cells toward a ground or sea service area via a service link antenna of a terrestrial base station that forms a cell toward a ground service area or a relay communication station provided on an aircraft located in the air, and wirelessly communicates with multiple terminal devices located in the cell, a program code for pre-calculating radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or a plurality of transmission points assumed for the terrestrial base station or the aerial relay type communication relay device and a plurality of reception points assumed for the service area; a program code for storing the pre-calculated calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths; program code for estimating the locations of a plurality of terminal devices within the service area; a program code for optimizing antenna parameters of a service link antenna based on calculation results of radio wave propagation characteristics of the plurality of radio wave propagation paths and estimation results of positions of the plurality of terminal devices; program code for applying the optimized values ​​of the antenna parameters to the service link antenna after the optimization is completed; A program comprising:

18. A program executed by a computer or processor provided in a remote control device capable of communicating with a terrestrial base station or an aerial relay type communication relay device, a program code for pre-calculating radio wave propagation characteristics for each of a plurality of radio wave propagation paths between one or a plurality of transmission points assumed for the terrestrial base station or the aerial relay type communication relay device and a plurality of reception points assumed for a service area; a program code for storing the pre-calculated calculation results of the radio wave propagation characteristics of the plurality of radio wave propagation paths; program code for estimating the locations of a plurality of terminal devices within the service area; a program code for optimizing antenna parameters of a service link antenna based on calculation results of radio wave propagation characteristics of the plurality of radio wave propagation paths and estimation results of positions of the plurality of terminal devices; a program code for transmitting the optimal value of the antenna parameter after the optimization is completed to the terrestrial base station or the communication relay device; A program comprising:

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