Communication system and communication method

Abstract

To provide a communication system capable of suppressing a decrease in communication throughput.SOLUTION: A communication system 1 includes an acquisition unit 12 and a setting unit 19. The acquisition unit 12 acquires the current position information of the stratospheric platform 3, the current position information of the user unit U, and the information of the digital twin. The information of the digital twin indicates map information in an actual three dimensional space. The setting unit 19 sets a beam pattern used for communication between the stratospheric platform 3 and the user terminal U on the basis of the positional relationship between the stratospheric platform and the position information of the user terminal U in the map information.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a communication system and a communication method. [Background technology]

[0002] A communication system using a stratospheric platform (HAPS: High Altitude Platform Station) is known (see, for example, Non-Patent Document 1). For example, an unmanned aerial vehicle is used as the HAPS. In this communication system, the flying HAPS searches for a user terminal, and communication is carried out between the HAPS and the user terminal. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Yuta NAKAMOTO, Naoki HASEGAWA, Yoshichika OHTA and Naoki SHINOHARA, “A Study on Microwave Power Transfer System to High Altitude Platform Station Considering Rectification Efficiency,” Space Solar Power Generation, vol.6 (2021), pp. 38-41 Summary of the Invention [Problem to be solved by the invention]

[0004] HAPS is required to cover the area where user terminals are present. For this reason, the beam pattern is controlled to cover each cluster. However, communication throughput varies depending on the distribution of user terminals. Communication throughput decreases in areas with a large number of users.

[0005] Furthermore, there is a risk that the beam may be blocked by obstacles such as buildings and environmental information such as terrain between the HAPS and the user terminal. In this case, the beam pattern may not be controlled properly, and communication throughput may decrease. In particular, communication between a HAPS located in the stratosphere and a user terminal is closely related to environmental information not only in the horizontal direction but also in the vertical direction.

[0006] An object of one aspect of the present invention is to provide a communication system and a communication method that can suppress a decrease in communication throughput. [Means for solving the problem]

[0007] A communication system according to one aspect of the present invention includes an acquisition unit and a setting unit. The acquisition unit acquires current position information of the stratospheric platform, current position information of the user terminal, and digital twin information. The digital twin information indicates map information in actual three-dimensional space. The setting unit sets a beam pattern to be used for communication between the stratospheric platform and the user terminal based on the positional relationship between the stratospheric platform and the position information of the user terminal in the map information.

[0008] A communication method according to another aspect of the present invention includes acquiring current position information of a stratospheric platform, current position information of a user terminal, and digital twin information indicating map information in actual three-dimensional space, and setting a beam pattern to be used for communication between the stratospheric platform and the user terminal based on the positional relationship between the stratospheric platform and the position information of the user terminal in the map information. The digital twin information indicates the map information in actual three-dimensional space. [Effects of the Invention]

[0009] One aspect of the present invention provides a communication system and a communication method that can suppress a decrease in communication throughput. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram of a communication system according to an embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram illustrating a communication system. [Figure 3] 10A shows the strength of received signal power in the embodiment, and FIG. 10B shows the strength of received signal power in a modified example of the embodiment. [Figure 4] 10(a) and 10(b) are diagrams for explaining the influence of HPAS movement. [Figure 5] FIG. 1 is a schematic diagram illustrating communication using a digital twin. [Figure 6] 10(a) to 10(d) are diagrams for explaining determination of cells in a coverage area. [Figure 7] FIG. 10 is a diagram for explaining cell determination in a modified example of the present embodiment. [Figure 8] 10(a) and 10(b) are diagrams for explaining parameters relating to a beam pattern. [Figure 9] FIG. 2 illustrates an example of a hardware configuration. [Figure 10] 10 is a graph showing simulation results of throughput. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Description of the embodiments of the present disclosure]

[0012] First, embodiments of the present disclosure will be listed and described.

[0013] [1] A communication system according to an embodiment of the present disclosure includes an acquisition unit and a setting unit. The acquisition unit acquires current location information of a stratospheric platform, current location information of a user terminal, and digital twin information. The digital twin information indicates map information in an actual three-dimensional space. The setting unit sets a beam pattern to be used for communication between the stratospheric platform and the user terminal based on the positional relationship between the stratospheric platform and the location information of the user terminal in the map information.

[0014] In the communication system described in [1] above, map information in three-dimensional space is shown in the digital twin. A beam pattern used for communication between the stratospheric platform and the user terminal is set based on the positional relationship between the stratospheric platform and the positional information of the user terminal in the map information. In this case, the beam pattern can be set more appropriately by taking into account environmental information in three-dimensional space. As a result, a decrease in communication throughput can be suppressed.

[0015] [2] The communication system of [1] above may further include a prediction unit. The prediction unit predicts a communication state between the stratospheric platform and the user terminal based on the positional relationship. The setting unit may set a beam pattern to be used for communication between the stratospheric platform and the user terminal based on the communication state predicted by the prediction unit. In this case, attenuation of the beam from the stratospheric platform is predicted, and the communication state between the stratospheric platform and the user terminal can be predicted more accurately. As a result, a decrease in communication throughput can be more accurately suppressed.

[0016] [3] In the communication system of [1] or [2] above, the prediction unit may re-predict the communication state between the stratospheric platform and the user terminal based on the beam pattern set by the setting unit and the positional relationship. The setting unit may set the beam pattern used for communication between the stratospheric platform and the user terminal based on the communication state re-predicted by the prediction unit. In this case, since the communication state is predicted based on the beam pattern set by the setting unit as well, the normal state can be predicted more accurately.

[0017] [4] In the communication system according to any one of [1] to [3] above, the setting unit may set a beam pattern to cover a plurality of user terminals in a divided manner. The beam pattern may be set so as to reduce communication throughput. In this case, the beam pattern may be set more appropriately.

[0018] [5] In another aspect of the present disclosure, a communication method includes acquiring current location information of a stratospheric platform, current location information of a user terminal, and digital twin information, and setting a beam pattern to be used for communication between the stratospheric platform and the user terminal based on a positional relationship between the stratospheric platform and the location information of the user terminal in the map information. The digital twin information represents map information in an actual three-dimensional space. [Details of the embodiments of the present disclosure]

[0019] Hereinafter, an embodiment of a communication system according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

[0020] First, a schematic configuration of a communication system according to an embodiment of the present disclosure will be described with reference to Fig. 1 to Fig. 8. Fig. 1 is a block diagram of a communication system 1 according to this embodiment. Fig. 2 is a schematic diagram of the communication system 1.

[0021] The communication system 1 is a radio station using a stratospheric platform. Hereinafter, the stratospheric platform is referred to as a HAPS (High Altitude Platform Station). The communication system 1 includes a base station 2, a HAPS 3, and a storage 40. In the communication system 1, the base station 2 communicates with a user device U via the HAPS 3. The communication system 1 transmits or receives information to the user device U, or transmits and receives information corresponding to the user device U, via the HAPS 3. In this specification, "communication" includes only transmitting information, only receiving information, and all of transmitting and receiving information. The communication system 1 provides a strong line-of-sight link with one or more user devices U. The user device U is, for example, a user terminal used for mobile communication.

[0022] The base station 2 communicates with the HAPS 3. The base station 2 is located on the ground, for example, as shown in Figure 2. The base station 2 is, for example, a gateway station.

[0023] The HAPS 3 relays signals received from the base station 2. The HAPS 3 is, for example, an unmanned aerial vehicle located in the stratosphere as shown in FIG. 2. The altitude at which the HAPS 3 is located is, for example, in the range of 20 km to 50 km. The unmanned aerial vehicle used as the HAPS 3 is, for example, a stratospheric airship. The unmanned aerial vehicle used as the HAPS 3 may also be an airplane or a balloon. The airplane used as the HAPS 3 may also be a solar plane.

[0024] The HAPS3 is equipped with multiple antennas 10 and communicates with a user device U via the multiple antennas 10. The HAPS3 communicates with a user device U located in a coverage area AR. The HAPS3 receives signals from the user device U. The coverage area AR corresponds to a communication area in which communication is possible using the HAPS3. For example, the coverage area AR is a ground area covered by the HAPS3. The diameter of the coverage area AR ranges, for example, from 40 km to 200 km. The coverage area AR includes multiple regions BR. The region BR corresponds to a cluster. Setting multiple regions BR in the coverage area AR is called "clustering." The HAPS3 sets a beam pattern corresponding to each of the multiple regions BR. A unit area of ​​the beam pattern on the ground is called a cell CL.

[0025] 3(a) and 3(b) show the strength of received signal power in a coverage area AR. In FIGS. 3(a) and 3(b), the strength of received signal power is shown by SINR (Signal to Interference and Noise Ratio). In FIGS. 3(a) and 3(b), the range with a higher SINR is shown in black, and the range with a lower SINR is shown in white. FIG. 3(a) shows a state in which three cells CL are uniformly configured. FIG. 3(b) shows a state in which nine cells CL are uniformly configured. The nine cells CL shown in FIG. 3(b) are configured in two layers, with three cells CL arranged on the inside and six cells CL arranged on the outside.

[0026] The HAPS 3 moves due to unexpected factors, for example, as shown in FIGS. 4(a) and 4(b). FIGS. 4(a) and 4(b) are diagrams for explaining the influence of the movement of the HPAS. For example, the HAPS 3 moves due to wind. In FIG. 4(a), the HAPS 3 moves horizontally relative to the ground. In FIG. 4(b), the HAPS 3 moves rotationally around a vertical axis. The movement of the HAPS 3 may also move the coverage area AR. As a result, the received signal power from the user equipment U may decrease at the HAPS 3. The decrease in the strength of the received signal power may increase the number of user equipment U whose communication throughput decreases.

[0027] Regarding the throughput at the user device U, equation (1): T j k =(b j / k j )*log2(1+γ k ) holds. "J" is the number of antenna arrays and also the number of cells. "j" means the jth cell. "K j " is the number of user equipments U in the j-th cell. j k " is the throughput of the kth user equipment U in the jth cell. j ” is the bandwidth allocated to the j-th cell. “γ k ” is the SINR of the kth user device U. The smaller the bandwidth, the more gradual the increase in throughput with an increase in SINR. Therefore, if the bandwidth is secured, the throughput can also be secured. The bandwidth allocated equally to each user device U is b j / k j is.

[0028] The storage 40 stores the digital twin DT. The digital twin DT is a reproduction in a virtual world (virtual space) of a physical object, system, or process that exists in the real world. The digital twin DT reflects, for example, the behavior, state, characteristics, etc. of an object in the real world in real time. Analysis, simulation, prediction, optimization, etc. can be performed based on the information in the digital twin DT.

[0029] The storage 40 communicates with, for example, at least one of the base station 2, the HAPS 3, and the user device U. The communication system 1 communicates with the user device U based on current location information of the HAPS 3, current location information of the user device U, and information on the digital twin DT. The location information of the HAPS 3 and the location information of the user device U are three-dimensional location information in the X-axis, Y-axis, and Z-axis directions. The digital twin DT stored in the storage 40 represents map information in actual three-dimensional space. The digital twin DT includes information on the shape and location of three-dimensional buildings, for example, as shown in FIG. 5. The digital twin DT may further include three-dimensional topographical information.

[0030] Figure 5 shows an overview of communication using the digital twin DT. The communication system 1 acquires information about the digital twin DT, applies the current location information of the HAPS3 and the current location information of the user device U to the information about the digital twin DT, and controls the beam pattern used for communication. In other words, the communication system 1 sets multiple cells CL based on the information about the digital twin DT, the current location information of the HAPS3, and the current location information of the user device U so that communication throughput is reduced.

[0031] As shown in FIG. 1 , the communication system 1 includes a search unit 11, an acquisition unit 12, a density calculation unit 13, a division position setting unit 14, a region determination unit 15, a determination unit 16, an antenna control unit 17, a prediction unit 18, a beam control unit 19, and a storage unit 20. The beam control unit 19 corresponds to a setting unit. In the example shown in this embodiment, the HAPS 3 includes the search unit 11 and the antenna control unit 17. The base station 2 includes the acquisition unit 12, the density calculation unit 13, the division position setting unit 14, the region determination unit 15, the determination unit 16, the prediction unit 18, and the beam control unit 19. As a variation of this embodiment, the HAPS 3 may include at least one of the acquisition unit 12, the density calculation unit 13, the division position setting unit 14, the region determination unit 15, the determination unit 16, the prediction unit 18, and the beam control unit 19, in addition to the search unit 11 and the antenna control unit 17.

[0032] The search unit 11 searches for user devices U located in a coverage area AR of the HAPS 3. For example, the search unit 11 searches for user devices U to acquire location information of each user device U in the coverage area AR.

[0033] The acquisition unit 12 acquires current location information of the HAPS3, current location information of the user device U, and digital twin information indicating map information in actual three-dimensional space. The acquisition unit 12 acquires the current location information of the HAPS3 and the current location information of the user device U by communicating with the HAPS3. The acquisition unit 12 acquires search results for user devices U located in the coverage area AR of the HAPS3, and acquires location information for user devices U located in each of a plurality of search ranges. In other words, the acquisition unit 12 acquires distribution information for user devices U in the coverage area AR of the HAPS3. The acquisition unit 12 acquires information on the digital twin DT from the storage 40. In addition to the search results, the acquisition unit 12 may also acquire information output from each functional unit in the communication system 1 or the user device U.

[0034] The density calculation unit 13 calculates the density of the number of users in each of the multiple search ranges based on the search results acquired by the acquisition unit 12. For example, the density calculation unit 13 calculates the density of the number of users in the search range by equation (3): D=K / S, where "D" is the density of the number of user devices U, "K" is the number of user devices U in the search range, and "S" is the area of ​​the search range.

[0035] The division position setting unit 14 uses the search results to set division positions for dividing the coverage area AR of the stratospheric platform. The division position setting unit 14 sets division positions for dividing multiple search ranges based on the calculation results of the density calculation unit 13. The division position setting unit 14 sets division positions for dividing search ranges that have a lower user density than the search range as division positions for dividing the coverage area AR of the stratospheric platform. The division position setting unit 14 sets division positions at positions in the search range with the lowest user density. For example, the division position setting unit 14 sets division positions for dividing the search range with the lowest user density among the multiple search ranges based on the user density in each of the multiple search ranges.

[0036] For example, the division position setting unit 14 sets a line that divides the search range as the division position. The division line is, for example, a line that divides the area of ​​the search range into two equal parts. For example, the division position setting unit 14 sets a line that divides the search range with the smallest user density as the division position.

[0037] For example, as shown in FIG. 6(a), the search unit 11 scans the coverage area AR in a sector V having an angle ω1 in a counterclockwise direction. When viewed vertically, the sector V has a fan shape with a center C. For example, the center C is the position of the HAPS 3. As a modification of this embodiment, the center C may be a predetermined position other than the position of the HAPS 3. Based on the calculation result of the density calculation unit 13, the search unit 11 finds a search range L1 with the smallest density of users.

[0038] Next, as shown in Figure 6(b), the search unit 11 scans the search range L1 counterclockwise in a sector V having an angle ω2. The search unit 11 finds the search range L2 with the smallest user density based on the calculation result of the density calculation unit 13. The division position setting unit 14 sets the midline of the search range L2 as the division position P.

[0039] The region determination unit 15 determines a plurality of regions BR that are included in the coverage area AR and correspond to the beam pattern from the HAPS 3, based on the division positions set by the division position setting unit 14.

[0040] As shown in FIG. 2, the multiple regions BR are regions that do not overlap one another. Each of the multiple regions BR is located adjacent to an adjacent region BR. As shown in FIG. 6(c), the region determination unit 15 determines the positions of the multiple regions BR so that the division position P set by the division position setting unit 14 is the boundary between two adjacent regions BR. For example, the region determination unit 15 uses the division position P as the boundary between the multiple regions BR, and scans the coverage area AR counterclockwise, sequentially determining J regions BR1, ..., BR2. i ,…,BR j Determine the position of

[0041] In the example shown in this embodiment, the region determination unit 15 calculates the average number of users by dividing the total number of users in the coverage area AR by the number of multiple regions BR to be determined. The region determination unit 15 determines the positions of the multiple region BRs based on the division positions set by the division position setting unit 14 and the average number of users. The region determination unit 15 determines the positions of the multiple region BRs so that the number of users in each of the multiple region BRs to be determined is equal to the average number of users. As a result, multiple region BRs having the same number of users can be set. The J region BRs are, for example, regions obtained by dividing the coverage area AR by the same number of user equipments U. In this case, the number of user equipments U in each region BR is K / J. As shown in FIG. 6(d), a cell CL is determined so that the maximum half-power beam width covers the user equipments U in the region BR.

[0042] As a modification of this embodiment, the region determination unit 15 may determine multiple regions BR so that each region BR has the same size. As another modification, the region determination unit 15 may determine the positions of multiple regions BR based on the throughput of a user device U located in each region BR. The region determination unit 15 may determine the positions of multiple regions BR so that a predetermined percentile value of the throughput of a user device U located in each region BR is equal. For example, the region determination unit 15 may determine the positions of multiple regions BR so that a 5th percentile value of the throughput of a user device U located in each region BR is equal. For example, the region determination unit 15 may determine the positions of multiple regions BR so that a 50th percentile value of the throughput of a user device U located in each region BR is equal.

[0043] As a modification of this embodiment, the coverage area AR may be divided into a plurality of regions BR1 to BR7. In Fig. 7, the coverage area AR is divided into a coverage area AR1 and a coverage area AR2. The coverage area AR1 is provided along the outer periphery of the coverage area AR2. A division position P1 is set in the coverage area AR1, and four regions BR1, BR2, BR3, and BR4 are determined in counterclockwise order from the division position P1. A division position P2 is set in the coverage area AR2, and three regions BR5, BR6, and BR7 are determined in counterclockwise order from the division position P2.

[0044] The determination unit 16 determines characteristics when a beam pattern is irradiated onto the multiple regions BR determined by the region determination unit 15. The characteristics determined by the determination unit 16 are, for example, communication throughput values. The communication throughput is, for example, the throughput of a user device U located in each region BR. For example, the throughput of a user device U located in each region BR is calculated by the determination unit 16 based on the SINR of the user device U, the number of users, and the allocated bandwidth. The region determination unit 15 determines the positions of the multiple regions BR based on, for example, the communication throughput values ​​determined by the determination unit 16.

[0045] For example, the setting of the division position P by the division position setting unit 14 and the determination by the determination unit 16 may be repeated. For example, a flow in which the setting of the division position P by the division position setting unit 14, the determination of multiple regions BR by the region determination unit 15, and the determination by the determination unit 16 are performed in this order may be repeated. In this case, the division position setting unit 14 sets the division position based on, for example, the determination result of the determination unit 16. The region determination unit 15 determines the multiple regions BR based on, for example, the division position set based on the determination result of the determination unit 16.

[0046] The antenna control unit 17 controls the antenna 10 provided in the HAPS 3. The antenna control unit 17 sets the antenna 10 based on information determined by the beam control unit 19. For example, the antenna control unit 17 sets the antenna 10 according to parameters determined by the beam control unit 19. The parameters of the antenna 10 are set, for example, by a geometric model. For example, the antenna control unit 17 controls the physical state of the antenna, the tilt of the antenna 10, and the like, according to the parameters determined by the beam control unit 19.

[0047] The prediction unit 18 predicts the communication state between the HAPS 3 and the user apparatus U based on the position information of the HAPS 3, the position information of the user apparatus U, and the information of the digital twin DT. For example, the prediction unit 18 predicts the communication state between the HAPS 3 and the user apparatus U based on the positional relationship between the HAPS 3 and the position information of the user apparatus U in map information. For example, the prediction unit 18 predicts beam attenuation in communication between the HAPS 3 and the user apparatus U as the communication state between the HAPS 3 and the user apparatus U. Beam attenuation in communication occurs, for example, when an obstruction is located between the HAPS 3 and the user apparatus U. An example of the obstruction is a building. Therefore, for example, beam attenuation may occur when a building is located between the HAPS 3 and the user apparatus U or when the user apparatus U is inside a building. The communication state between the HAPS 3 and the user apparatus U is, for example, the throughput in communication between the HAPS 3 and the user apparatus U. The prediction unit 18 may predict the throughput in communication between the HAPS 3 and the user device U from the location information of the HAPS 3, the location information of the user device U, and the information of the digital twin DT.

[0048] The prediction unit 18 may predict, for example, the timing when an obstruction appears between the HAPS 3 and the user device U, making the line of sight impossible, and the timing when the line of sight environment changes from an impossible line of sight environment, based on the position information of the HAPS 3, the position information of the user device U, and the information of the digital twin DT. The prediction unit 18 may predict the communication state between the HAPS 3 and the user device U at these timings.

[0049] Furthermore, the prediction unit 18 re-predicts the communication state between the HAPS 3 and the user apparatus U based on the beam pattern set in the beam control unit 19, the position information of the HAPS 3, the position information of the user apparatus U, and the information of the digital twin DT. In other words, the prediction unit 18 re-predicts the communication state between the HAPS 3 and the user apparatus U based on the beam pattern set in the beam control unit 19 and the positional relationship between the stratospheric platform and the position information of the user apparatus U in the map information. The prediction unit 18 may sequentially predict the attenuation of the beam between the HAPS 3 and the user apparatus U, for example, based on the beam pattern set in the beam control unit 19, the position information of the HAPS 3, the position information of the user apparatus U, and the information of the digital twin DT.

[0050] The beam control unit 19 sets a beam pattern used for communication between the HAPS 3 and the user device U. For example, the beam control unit 19 modifies the region BR determined by the region determination unit 15. The beam control unit 19 and the region determination unit 15 may be the same unit. The beam control unit 19 sets a beam pattern used for communication between the HAPS 3 and the user device U based on the positional relationship between the HAPS 3 and the positional information of the user device U in the map information.

[0051] The beam control unit 19 sets a beam pattern to be used for communication between the HAPS 3 and the user device U, based on the communication state re-predicted by the prediction unit 18. For example, the beam pattern setting by the beam control unit 19 and the prediction of the communication state between the HAPS 3 and the user device U based on the set beam pattern may be repeated.

[0052] The beam control unit 19 sets a beam pattern to cover multiple user devices U in a divided manner. The beam control unit 19 sets a beam pattern in each region BR based on the communication state predicted by the prediction unit 18 so as to suppress a decrease in communication throughput. For example, the beam control unit 19 sets a beam pattern so as to ensure communication quality of each user device U based on the communication state between each user device U and the HAPS 3 predicted by the prediction unit 18. For example, the beam control unit 19 may set a beam pattern when the prediction unit 18 predicts that an obstruction will occur between the HAPS 3 and the user device U, resulting in non-line-of-sight, and when the prediction unit 18 predicts that the non-line-of-sight environment will change to a line-of-sight environment.

[0053] For example, the beam control unit 19 determines parameters related to the set beam pattern. FIGS. 8(a) and 8(b) are diagrams for explaining parameters related to the beam pattern. The parameters related to the beam pattern are, for example, antenna parameters. The beam control unit 19 sequentially resets the beam pattern from the HAPS3 and determines parameters related to the set beam pattern. The resetting frequency is, for example, several milliseconds to several tens of seconds. The beam control unit 19 determines multiple cells CL that are included in the coverage area AR and correspond to the beam pattern from the HAPS3. In the example shown in this embodiment, the multiple cells CL have the same size. The multiple cells CL are areas that do not overlap with each other. Each of the multiple cells CL is located adjacent to an adjacent cell CL.

[0054] The beam control unit 19 determines the half-power bandwidth “θ” in the vertical direction based on the radius of the cell CL. 3dB " and the horizontal half-power bandwidth "φ 3dB " and the vertical half-power band "θ 3dB " is expressed by the following equation (4). The horizontal half-power bandwidth "φ 3dB " is expressed by the following equation (5).

number

number

[0055] "h" is the altitude of HAPS3. "g" is the distance between the center of cell CL and HAPS3 when viewed vertically. In other words, "g" is the distance between the center of cell CL and the projected position of HAPS3 on the ground. "r" is the radius of cell CL.

[0056] The beam control unit 19 calculates the change in vertical tilt "Δθ" based on the center position of the cell CL before the movement and the center position of the cell CL after the movement. tilt " and the change in horizontal tilt "Δφ tilt " is obtained. Here, cell CL A From Cell CL B The change in vertical tilt “Δθ tilt " is expressed by the following equation (6). The change in horizontal tilt "Δφ tilt " is expressed by the following equation (7). "g A " is Cell CL A is the distance between the center of the map and the projected position of HAPS3 on the ground. B " is Cell CL B is the distance between the center of the map and the projected position of HAPS3 on the ground. a " and "y a " is Cell CL A It corresponds to the center coordinate of "x b " and "y b " is Cell CL B corresponds to the coordinates of the center of

number

number

[0057] After the clustering is performed by the division position setting unit 14 and the region determination unit 15 and the antenna parameters are designed by the geometric coverage model, the beam control unit 19 fine-tunes the antenna parameters so as to maximize the throughput of the user equipment U in each cell CL. The antenna parameters are the vertical half-power width “θ 3dB " and the horizontal half-power width "φ 3dB " and the change in vertical tilt "Δθ tilt " and the change in horizontal tilt "Δφ tilt The beam control unit 19 fine-tunes the antenna parameters by, for example, DQN (deep Q-Network) so as to maximize the throughput of the user device U in each cell CL.

[0058] Next, the hardware configuration of the base station 2 and the HAPS 3 will be described with reference to Fig. 9. Fig. 9 is a diagram showing an example of the hardware configuration of the base station 2 and the HAPS 3.

[0059] In the communication system 1, the base station 2 and the HAPS 3 each include a processor 101, a main memory device 102, an auxiliary memory device 103, a communication device 104, an input device 105, and an output device 106. The base station 2 and the HAPS 3 each include one or more computers configured with this hardware and software such as programs. The search unit 11, the acquisition unit 12, the density calculation unit 13, the division position setting unit 14, the region determination unit 15, the determination unit 16, the antenna control unit 17, the prediction unit 18, and the beam control unit 19 may each be configured with one computer or multiple computers. The base station 2 and the HAPS 3 are realized in cooperation with hardware.

[0060] When the search unit 11, the acquisition unit 12, the density calculation unit 13, the division position setting unit 14, the region determination unit 15, the judgment unit 16, the antenna control unit 17, the prediction unit 18, and the beam control unit 19 are configured by multiple computers, these computers may be connected locally or via a communication network such as the Internet or an intranet. This connection logically constructs a single search unit 11, acquisition unit 12, the density calculation unit 13, the division position setting unit 14, the region determination unit 15, the judgment unit 16, the antenna control unit 17, the prediction unit 18, and the beam control unit 19.

[0061] The processor 101 executes an operating system, application programs, etc. The main memory device 102 is composed of a read-only memory (ROM) and a random access memory (RAM). For example, at least some of the various functional units of the base station 2 and the HAPS 3 can be realized by the processor 101 and the main memory device 102.

[0062] The auxiliary storage device 103 is a storage medium configured with a hard disk, a flash memory, etc. The auxiliary storage device 103 generally stores a larger amount of data than the main storage device 102. For example, at least a part of the acquisition unit 12 can be realized by the auxiliary storage device 103.

[0063] The communication device 104 is configured by a network card or a wireless communication module. For example, at least a part of the acquisition unit 12 can be realized by the communication device 104. The input device 105 is configured by an input port, a keyboard, a mouse, a touch panel, etc. For example, at least a part of the acquisition unit 12 can be realized by the input device 105. The output device 106 is configured by an output port, a display, a projection device such as a projector, etc.

[0064] The auxiliary storage device 103 stores in advance a program and data necessary for processing. This program causes a computer to execute each functional element of the base station 2 and the HAPS 3. This program causes the computer to execute, for example, each process performed in a communication method described below. As the communication method, for example, the process performed in the communication system described above is performed. This program may be provided after being recorded on a tangible recording medium such as a CD-ROM, a DVD-ROM, or a semiconductor memory. This program may also be provided as a data signal via a communication network.

[0065] Next, the effects of the communication system and communication method according to the above-described embodiment will be described.

[0066] In the communication system 1, map information in a three-dimensional space is shown in the digital twin DT. A beam pattern used for communication between the HAPS 3 and the user device U is set based on the positional relationship between the HAPS 3 and the positional information of the user device U in the map information. In this case, the beam pattern can be set more appropriately taking into account environmental information in the three-dimensional space. As a result, a decrease in communication throughput can be suppressed.

[0067] In the example shown in this embodiment, in the communication system 1, the prediction unit 18 predicts the communication state between the HAPS 3 and the user equipment U from the above-mentioned positional relationship. The beam control unit 19 sets a beam pattern to be used for communication between the HAPS 3 and the user equipment U based on the communication state predicted by the prediction unit 18. In this case, attenuation of the beam from the HAPS 3 is predicted, and the communication state between the HAPS 3 and the user equipment U can be predicted more accurately. As a result, a decrease in communication throughput can be more accurately suppressed.

[0068] In the example shown in the present embodiment, in the communication system 1, the prediction unit 18 re-predicts the communication state between the HAPS 3 and the user device U based on the beam pattern set in the beam control unit 19 and the above-mentioned positional relationship. The beam control unit 19 sets the beam pattern to be used for communication between the HAPS 3 and the user device U based on the communication state re-predicted by the prediction unit 18. In this case, since the communication state is predicted based also on the beam pattern set in the beam control unit 19, the normal state can be predicted more accurately.

[0069] In the example shown in this embodiment, in the communication system 1, the beam control unit 19 sets a beam pattern to cover a plurality of user devices U in a divided manner. The beam pattern is set so as to reduce communication throughput. In this case, the beam pattern can be set more appropriately.

[0070] Next, a simulation result of the throughput performance of the user equipment U in the communication system 1 and a comparative example will be described with reference to Fig. 10. Fig. 10 is a graph showing the simulation result of the throughput of communication using HAPS. Fig. 10 shows the CDF (cumulative distribution function) of the throughput of the user equipment U.

[0071] This simulation was performed in the Tokyo area. Data D1 shows data for which communication was performed using a default beam pattern without using the digital twin DT or distribution information of the user device U. Data D2 shows data for which a beam pattern was set using distribution information of the user device U without using the digital twin DT and for which communication was performed. Data D3 shows data for which a beam pattern was set using the digital twin DT and distribution information of the user device U and for which communication was performed. As shown in these data D1 to D3, when a beam pattern was set using the digital twin DT and distribution information of the user device U, it was confirmed that the user device U with low throughput was reduced and throughput was ensured. In other words, it was confirmed that a decrease in communication throughput was suppressed.

[0072] The above describes embodiments and modifications of the present invention, but the present invention is not necessarily limited to the above-described embodiments and modifications, and various modifications are possible without departing from the spirit of the present invention.

[0073] For example, the communication system 1 may include a plurality of base stations 2. The communication system 1 may include a plurality of HAPSs 3.

[0074] The storage 40 may be included in the base station 2, the HAPS 3, or the user equipment U. The digital twin DT may be stored in the storage unit 20. [Explanation of symbols]

[0075] 1...Communication system, 3...HAPS, 12...Acquisition unit, 18...Prediction unit, 19...Beam control unit, DT...Digital twin.

Claims

1. an acquisition unit that acquires current location information of the stratospheric platform, current location information of the user terminal, and digital twin information indicating map information in actual three-dimensional space; a setting unit that sets a beam pattern to be used for communication between the stratospheric platform and the user terminal based on a positional relationship between the stratospheric platform and position information of the user terminal in the map information.

2. a prediction unit that predicts a communication state between the stratospheric platform and the user terminal based on the positional relationship; The communication system according to claim 1 , wherein the setting unit sets a beam pattern to be used for communication between the stratospheric platform and the user terminal based on the communication state predicted by the prediction unit.

3. the prediction unit re-predicts a communication state between the stratospheric platform and the user terminal based on the beam pattern set by the setting unit and the positional relationship; The communication system according to claim 2 , wherein the setting unit sets a beam pattern used for communication between the stratospheric platform and the user terminal based on the communication state re-predicted by the prediction unit.

4. the setting unit sets the beam pattern so as to cover the plurality of user terminals in a divided manner; The communication system according to claim 1 or 2, wherein the beam pattern is set so that a throughput of the communication is reduced.

5. Acquiring current location information of the stratospheric platform, current location information of the user terminal, and digital twin information indicating map information in actual three-dimensional space; setting a beam pattern to be used for communication between the stratospheric platform and the user terminal based on a positional relationship between the stratospheric platform and position information of the user terminal in the map information.

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