Radio communication system

Abstract

The present invention provides a radio communication system capable of suppressing interference between a reception signal received from a ground terminal and a reception signal received from an aerial terminal by a base station, in a three-dimensional space cell configuration that achieves sharing of the same frequency band between a ground cell and an aerial cell. The base station provided in the radio communication system comprises: an antenna; a radio communication unit that forms the ground cell and the aerial cell using the same frequency band, and performs radio communication between the ground terminal and the aerial terminal via the antenna; a ground beam control unit that performs beamforming to direct a directional beam to the ground terminal; an aerial beam control unit that performs beamforming to direct a directional beam to the aerial terminal; and an interference suppression unit that superimposes an interference suppression weight for suppressing an interference signal from the aerial terminal on the reception signal received from the ground terminal via the antenna, and superimposes an interference suppression weight for suppressing an interference signal from the ground terminal on the reception signal received from the aerial terminal via the antenna.

Description

wireless communication system

[0001] The present invention relates to a wireless communication system for mobile communications.

[0002] In recent years, with the realization of drones, flying cars (taxis), etc., moving in the sky, the construction of aerial service areas for mobile communications where terminal devices can be used in the sky is expected. The present applicant has proposed a wireless communication system that uses the same base station to form ground cells toward the ground service area and also form sky cells toward the sky service area, thereby constructing a three-dimensional spatial cell configuration that enables the ground cells and sky cells to share the same frequency band (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-133975

[0004] In the three-dimensional spatial cell configuration that realizes the sharing of the same frequency band between the above-mentioned terrestrial cell and the aerial cell, there is a problem of wanting to reduce interference that may occur between the received signal received by the base station from the terrestrial terminal device and the received signal received by the aerial terminal device.

[0005] A system according to one aspect of the present invention is a wireless communication system including one or more base stations, wherein the base station includes an antenna capable of forming a plurality of different directional beams, a wireless communication unit that forms terrestrial cells and aerial cells each using the same frequency band and performs wireless communication via the antenna between a terrestrial terminal device located in the terrestrial cell and an aerial terminal device located in the aerial cell, a terrestrial beam control unit that performs beamforming to direct the directional beam toward the terrestrial terminal device, an aerial beam control unit that performs beamforming to direct the directional beam toward the aerial terminal device, and an interference suppression unit that superimposes an interference suppression weight on a received signal received from the terrestrial terminal device via the antenna to suppress an interference signal from the aerial terminal device, and that superimposes an interference suppression weight on a received signal received from the aerial terminal device via the antenna to suppress an interference signal from the terrestrial terminal device.

[0006] In the wireless communication system, the ground terminal device and the air terminal device are equipped with a transmission power control unit that controls transmission power to the base station based on transmission power control information received from the base station, and the base station estimates the amount of interference suppression for the ground terminal device and the air terminal device in the interference suppression unit, sets a transmission power threshold for transmission by the ground terminal device and the air terminal device according to the estimated amount of interference suppression, determines the amount of transmission power for the ground terminal device and the air terminal device according to the set transmission power threshold, and transmits the determined amount of transmission power to the ground terminal device and the air terminal device as the transmission power control information.

[0007] In the wireless communication system, the base station may include an interference suppression control unit that estimates the communication quality of the received signal received from the ground terminal device and the communication quality of the received signal received from the airborne terminal device, and switches on / off an interference suppression function that superimposes the interference suppression weight in the interference suppression unit based on the estimated communication quality.

[0008] In the wireless communication system, the base station may be provided with an interference suppression control unit that estimates an angular difference between the direction of the ground terminal device and the direction of the aerial terminal device based on the position of the antenna, and switches on / off an interference suppression function in the interference suppression unit that superimposes the interference suppression weight based on the estimated angular difference.

[0009] According to the present invention, in a three-dimensional spatial cell configuration in which the same frequency band is shared between terrestrial cells and aerial cells, it is possible to suppress interference between the received signal received by a base station from a terrestrial terminal device and the received signal received from an aerial terminal device.

[0010] FIG. 1 is an explanatory diagram showing an example of the configuration of a wireless communication system with a three-dimensional spatial cell configuration according to an embodiment. FIG. 2 is an explanatory diagram showing an example of interference occurring during uplink reception at a base station with a three-dimensional spatial cell configuration. FIG. 3 is an explanatory diagram showing an example of base station antenna adaptive beamforming at a base station with a three-dimensional spatial cell configuration. FIG. 4A is an explanatory diagram showing an example of the positional relationship between an airborne terminal located at a high altitude in an airborne cell and a terrestrial terminal located inside a terrestrial cell. FIG. 4B is an explanatory diagram showing an example of overlap between an airborne antenna beam directed toward the airborne terminal at the base station of FIG. 4A and a terrestrial antenna beam directed toward the terrestrial terminal. FIG. 5A is an explanatory diagram showing an example of the positional relationship between an airborne terminal located at a low altitude in an airborne cell and a terrestrial terminal located at the cell edge of the terrestrial cell. FIG. 5B is an explanatory diagram showing an example of overlap between an airborne antenna beam directed toward the airborne terminal at the base station of FIG. 5A and a terrestrial antenna beam directed toward the terrestrial terminal, and how interference occurs. FIG. 6 is an explanatory diagram showing an example of the main configuration of a base station in a wireless communication system according to an embodiment. FIG. 7 is an explanatory diagram showing an example of the basic configuration of an interference suppression system to which uplink interference suppression processing is applied in a wireless communication system according to an embodiment. FIG. 8 is an explanatory diagram showing an example of the configuration of an interference suppression system according to an embodiment. FIG. 9A is an explanatory diagram showing an example of the positional relationship between an airborne terminal located at a low altitude in an airborne cell and a terrestrial terminal located at the cell edge of a terrestrial cell when the interference suppression process in the interference suppression system of FIG. 8 is not applied. FIG. 9B is an explanatory diagram showing an example of the overlap of an airborne antenna beam directed toward the airborne terminal and a terrestrial antenna beam directed toward the terrestrial terminal at the base station of FIG. 9A, and how interference occurs. FIG. 10A is an explanatory diagram showing an example of the positional relationship between an airborne terminal located at a low altitude in an airborne cell and a terrestrial terminal located at the cell edge of a terrestrial cell when the interference suppression process in the interference suppression system of FIG. 8 is applied. FIG. 10B is an explanatory diagram showing an example of the overlap of an airborne antenna beam directed toward the airborne terminal and a terrestrial antenna beam directed toward the terrestrial terminal at the base station of FIG. 10A. FIG. 11 is an explanatory diagram showing another example of the configuration of an interference suppression system according to an embodiment.12A is an explanatory diagram showing an example of required received power before a setting change is applied to the transmission power control applied to the ground terminal and the airborne terminal of the interference suppression system of FIG. 11 . FIG. 12B is an explanatory diagram showing an example of required received power after a setting change is applied to the transmission power control applied to the ground terminal and the airborne terminal of the interference suppression system of FIG. 11 . FIG. 13 is an explanatory diagram showing another configuration example of an interference suppression system to which interference suppression processing is applied in a wireless communication system according to an embodiment. FIG. 14A is an explanatory diagram showing an example of the positional relationship between an airborne terminal located at a low altitude in an airborne cell and a ground terminal located at a cell edge of the ground cell when the interference suppression processing in the interference suppression system of FIG. 13 is turned OFF. FIG. 14B is an explanatory diagram showing an example of overlapping and interference occurring between an airborne antenna beam directed toward the airborne terminal and a terrestrial antenna beam directed toward the ground terminal in the base station of FIG. 14A . FIG. 15A is an explanatory diagram showing an example of the positional relationship between an airborne terminal located at a low altitude in an airborne cell and a ground terminal located at a cell edge of the ground cell when the interference suppression processing in the interference suppression system of FIG. 12 is turned ON. Fig. 15B is an explanatory diagram showing an example of overlap between an aerial antenna beam directed toward an aerial terminal and a terrestrial antenna beam directed toward a terrestrial terminal in the base station of Fig. 15A. Fig. 15C is an explanatory diagram showing an example of overlap between an aerial antenna beam directed toward an aerial terminal and a terrestrial antenna beam directed toward a terrestrial terminal in the base station of Fig. 15A. Fig. 16 is an explanatory diagram showing yet another configuration example of an interference suppression system to which interference suppression processing in a wireless communication system according to an embodiment is applied. Fig. 17A is an explanatory diagram showing an angle θ of the aerial terminal direction in the interference suppression system of Fig. 16. Ｕ and the angle θ in the direction of the terminal Ｄ 17B is an explanatory diagram showing an example of overlap between an aerial antenna beam directed toward an aerial terminal and a terrestrial antenna beam directed toward a terrestrial terminal, the aerial antenna beam having the angle difference of FIG. 17A. FIG. 18A is an explanatory diagram showing an example of selection of an optimal directional beam directed toward a terminal device from a base station antenna in a wireless communication system according to an embodiment. FIG. 18B is an explanatory diagram showing an example of selection of an optimal directional beam directed toward a terminal device from a base station antenna in a wireless communication system according to an embodiment.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The system according to the embodiment described herein is a wireless communication system with a three-dimensional spatial cell configuration that realizes the sharing of the same frequency between ground cells and sky cells when establishing a "ground service area" for mobile communications as well as an "air service area" for mobile communications that is expected to be realized with the realization of drones, flying cars (taxis), and the like. In the three-dimensional spatial cell configuration that realizes the sharing of the same frequency band between ground cells and sky cells, the wireless communication system of the embodiment combines base station antenna beamforming for terminal devices (ground terminals) located in ground cells and terminal devices (air terminals) located in sky cells with interference suppression processing (interference removal processing) that suppresses (removes) interference when the base station receives uplink signals from the ground terminals and sky terminals. This makes it possible to suppress interference between the signals received by the base station from the ground terminals and the sky terminals.

[0012] FIG. 1 is an explanatory diagram showing an example of the configuration of a wireless communication system with a three-dimensional spatial cell configuration according to an embodiment. The wireless communication system 10 according to this embodiment includes multiple base stations 20A-20C. The wireless communication system 10 may also include multiple base stations 20A-20C and multiple terminal devices 30A-30C and 40A-40C that communicate wirelessly with these base stations. While FIG. 1 illustrates three base stations 20A-20C and six terminal devices 30A-30C and 40A-40C, the number of base stations and terminal devices is arbitrary. For example, the wireless communication system 10 may include a single base station, two base stations, or four or more base stations. Furthermore, each base station may have a cell with multiple terminal devices. In mobile communications using a wideband frequency band, the wideband frequency is divided into multiple frequencies, and the number of terminal devices that can be simultaneously accommodated corresponds to the number of divided frequencies. However, the number of terminal devices that can be used at each divided frequency is one for each of the airborne cell and the terrestrial cell. Therefore, in this embodiment, there is one terminal device that simultaneously uses the same frequency with each base station in the air cell and one terminal device that uses the same frequency with each base station in the ground cell.

[0013] The wireless technology in the wireless communication system 10 of the present embodiment is, for example, a wireless technology that complies with the LTE (Long Term Evolution) / LTE-Advanced standard. The wireless technology in the wireless communication system 10 may also be a wireless technology in accordance with next-generation standards such as fifth generation (5G) and sixth generation (6G).

[0014] The base stations 20A to 20C are called, for example, eNodeB, gNodeB, etc., and relay communications between the terminal devices 30A to 30C, 40A to 40C and the mobile communication network.

[0015] The terminal devices 30A to 30C, 40A to 40C can connect to a mobile communication network via base stations 20A to 20C and perform various communications. The terminal devices are called user equipment (UE) because they are used by users of communication services. Furthermore, because the terminal devices are mobile, they are also called mobile stations or mobile devices, or radio devices.

[0016] The cells as wireless communication areas formed by each base station 20A to 20C in this embodiment include ground cells 100A to 100C as first cells formed in a ground service area (hereinafter referred to as the "ground area") A1, and aerial cells 200A to 200C as second cells formed in an aerial service area (hereinafter referred to as the "aerial area") A2.

[0017] Like existing general base stations, the ground cells 100A to 100C are two-dimensional or three-dimensional wireless communication areas for wireless communication with terminal devices (hereinafter also referred to as "ground terminals") 30A, 30B, and 30C located in a ground service area A1 (an area up to a certain height from the ground, for example, an area below the antenna of the base station). On the other hand, the aerial cells 200A to 200C are two-dimensional or three-dimensional wireless communication areas for wireless communication with terminal devices (hereinafter also referred to as "aerial terminals") 40A, 40B, and 40C located in an aerial service area A2 above the ground service area A1.

[0018] The ground terminals 30A, 30B, and 30C located in the ground service area A1 are, for example, portable communication terminals such as smartphones and tablet terminals carried by pedestrians, communication terminals mounted on IoT devices (sensors, cameras, etc.) installed in buildings on the ground, and communication terminals mounted on ground moving bodies such as automobiles and trains.

[0019] The aerial terminals 40A, 40B, and 40C located in the aerial service area A2 are, for example, communication terminals mounted on flying objects such as unmanned drones (UAVs: Unmanned Aerial Vehicles), manned drones, flying cars (taxi), helicopters, etc. The aerial terminal 40B may be a portable communication terminal such as a smartphone or tablet terminal carried by a passenger on board an aircraft, helicopter, or other flying object. In this embodiment, a case will be described in which the aerial terminal 40B is a communication terminal mounted on a drone 50B, as shown in FIG. 1 .

[0020] In this embodiment, the base stations 20A to 20C, the ground terminals 30A, 30B, and 30C, and the airborne terminals 40A, 40B, and 40C each perform wireless communication using wireless resources (frequency resources, time resources) allocated to each cell in a predetermined frequency band. The allocation of wireless resources is managed, for example, by the base stations 20A to 20C.

[0021] The duplexing method for the uplink and downlink of wireless communication between the base stations 20A to 20C and the ground terminals 30A, 30B, 30C and the airborne terminals 40A, 40B, 40C 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. Furthermore, the wireless communication access method is not limited to a specific method, and may be, for example, an FDMA (Frequency Division Multiple Access) method, a TDMA (Time Division Multiple Access) method, a CDMA (Code Division Multiple Access) method, or an OFDMA (Orthogonal Frequency Division Multiple Access) method.

[0022] In the above three-dimensional spatial cell configuration, the aerial service area A2 is constructed independently of the terrestrial service area A1, and the terrestrial service area A1 and the aerial service area A2 are constructed by the same base station, and the terrestrial service area A1 and the aerial service area A2 share the same frequency band. Therefore, same-frequency interference between the terrestrial cells 100A to 100C and the aerial cells 200A to 200C is an issue.

[0023] 2 is an explanatory diagram showing an example of interference occurring during uplink reception at base stations 20A and 20B in a three-dimensional spatial cell configuration. In FIG. 2, when base stations 20A and 20B are receiving radio waves of uplink signals from ground terminals and overhead terminals in their own cells, there is a risk of uplink interference occurring, in which radio waves of uplink signals from overhead terminals or ground terminals in other cells interfere. For example, when base station 20A is receiving radio waves of uplink signals from ground terminal 30A in its own cell 100A and overhead terminal 40A in its own cell 200A, there is a risk of interference from radio waves of uplink signals from ground terminal 30B in other cell 100B and overhead terminal 40B in other cell 200B. In particular, because the radio wave propagation path between base stations 20A and 20B and overhead terminal 40A and 40B is line-of-sight and free of obstacles, the radio waves of uplink signals reaching base stations 20A and 20B from overhead terminal 40A and 40B are relatively strong, making uplink interference more likely to occur.

[0024] To reduce the interference in the uplink, the following interference reduction techniques (A1) and (A2) are available. (A1) Base stations 20A, 20B, and 20C apply base station antenna adaptive beamforming, which directs directional beams (hereinafter also referred to as "beams" or "antenna beams") 102A, 102B, 202A, and 202B toward ground terminals 30A, 30B, and 30C and airborne terminals 40A, 40B, and 40C in their own cells. (A2) Adaptive transmit power control is applied to ground terminals 30A, 30B, and 30C and airborne terminals 40A, 40B, and 40C so that the received power from ground terminals 30A, 30B, and 30C and airborne terminals 40A, 40B, and 40C in their own cells at base stations 20A, 20B, and 20C reaches a predetermined received power (hereinafter also referred to as "required received power").

[0025] The interference reduction techniques (A1) and (A2) above can reduce same-frequency interference between terrestrial cells and overhead cells, enabling the sharing of the same frequency. Specifically, beamforming control at each base station can suppress interference from terminal devices in the same cell and other cells. Furthermore, beamforming control at each base station can increase the received power at the base station of the same cell, so that the transmission power at the terminal device can be significantly reduced (the amount of control can be significantly increased) compared to the case without beamforming control, thereby significantly suppressing interference to terminals in other cells.

[0026] 3 is an explanatory diagram showing an example of base station antenna adaptive beamforming in base stations 20A to 20C in a three-dimensional spatial cell configuration according to this embodiment. Antennas 26 of base stations 20A to 20C (hereinafter also referred to as "base station antennas") each emit a beam 102 for a terrestrial cell and a beam 202 for an aerial cell, each capable of forming directivities in different directions within a virtual vertical plane centered on the antenna. Antenna 26 may be an array antenna in which antenna elements, such as multiple dipole antennas or patch antennas (planar antennas), are arranged, and the amplitude and phase of the signal from each antenna element are controlled to form a beam with directivity in a predetermined direction.

[0027] In this embodiment, the antenna 26 is configured as an array antenna (hereinafter also referred to as a "base station array antenna") in which multiple antenna elements 261(1) to 261(3) are arranged two-dimensionally or three-dimensionally, and may be an antenna (hereinafter also referred to as a "massive antenna") that can be used in a massive MIMO (multiple-input and multiple-output) transmission method having a beamforming function that can control the number of beams, beam width, and beam direction. The number of antenna elements 261 of the antenna 26 is not limited to a specific number. However, the total number of antenna elements 261 must exceed the number of signals transmitted by terminals in terrestrial cells and airborne cells. For example, when MIMO transmission is performed using two transmitting antennas each in terrestrial cells and airborne cells, a minimum of four antenna elements (2 x 2) are required.

[0028] The shape of the massive antenna 26 is not limited to a specific shape. For example, the massive antenna 26 is a planar massive antenna in which a plurality of antenna elements 26a are arranged in a plane. A plurality of planar massive antennas 26 may be provided so as to form sector cell beams in a plurality of different directions in a horizontal plane centered on the base station. Alternatively, the massive antenna 26 may be a cylindrical massive antenna in which a plurality of antenna elements 261 are arranged on the outer periphery or bottom surface of the cylindrical antenna.

[0029] The beam width and beam direction of the beams 102, 202 formed by the massive antenna 26 can be controlled in the horizontal and vertical directions. The massive antenna 26 has a large number of antenna elements, for example, up to 128, and can allocate dedicated radio waves to each user using techniques such as beamforming and spatial multiplexing.

[0030] Each of the base stations 20A to 20C performs space division multiplexing by using a massive antenna 26 to perform vertical plane beamforming to separately form a directional beam for terrestrial terminals (hereinafter also referred to as a "terrestrial antenna beam") 102 and a directional beam for airborne terminals (hereinafter also referred to as an "airborne antenna beam") 202 in the same frequency band, thereby suppressing interference between the terrestrial cells 100A to 100C and the airborne cells 200A to 200C.

[0031] 3, each base station device 21 of base stations 20A to 20C includes a wireless communication unit 23 that performs wireless communication with ground terminals 30A to 30C and air terminals 40A to 40C via an antenna 26. In addition to the wireless communication unit 23, the base station device 21 also includes a scheduler, a control unit that is responsible for overall control and processing of the base station device 21, and a memory unit.

[0032] The wireless communication unit 23 has a transceiver 24 and a beam control unit (hereinafter also referred to as a "base station antenna BF control unit") 25. The beam control unit 25 in FIG. 3 functions as a ground beam control unit that performs beamforming to direct a directional beam toward the ground terminal 30, and also functions as an aerial beam control unit that performs beamforming to direct a directional beam toward the aerial terminal 40. The beam control unit 25 has a beam control device 251 and an antenna weight application unit 252. The beam control device 251 controls the antenna beam forming weights (hereinafter also referred to as "BF weights") w in the antenna weight application unit 252 to set the amplitude and phase of the received signals and transmitted signals of each of the multiple antenna elements 261(1) to 261(3) of the antenna (massive antenna) 26. Ｂ (w １ , w ２ , w ３ ) to set the

[0033] 3, the beam direction in the vertical plane is changed by adjusting the amplitude and phase (BF weight) of each antenna element 261 of the antenna 26. The beam forming control may be, for example, precoding control in which the amplitude and phase of the antenna element 261 are set in advance to generate beams in multiple different directions, or continuous tracking control in which the amplitude and phase of the antenna element 261 are set as appropriate to generate a beam in any direction.

[0034] By concentrating the transmission power to and reception power from the terminal devices (air terminal 40, ground terminal 30) using beams controlled by the above-mentioned beamforming control, it is possible to improve antenna gain and suppress interference with other cells other than the own cell. Furthermore, the antenna gain is improved, which improves reception power at the base station 20, and transmission power control technology of the terminal devices (air terminal 40, ground terminal 30) can significantly reduce transmission power, thereby significantly reducing interference with other cells.

[0035] In a wireless communication system with a three-dimensional spatial cell configuration that applies only the above-mentioned beamforming and transmission power control, the positional relationship between the airborne terminal 40 and the ground terminal 30 may result in a deterioration in communication quality or inability to obtain high transmission speeds.

[0036] For example, when an aerial terminal 40 is located at a high altitude in an aerial cell as shown in FIG. 4A and a ground terminal 30 is located inside a ground cell 100, there is no overlap between an aerial antenna beam 202 directed from the base station 20 to the aerial terminal 40 and a ground antenna beam 102 directed from the base station 20 to the ground terminal 30 as shown in FIG. 4B, so that interference between the aerial cell 200 and the ground cell 100 is small.

[0037] On the other hand, when the aerial terminal 40 is located at a low altitude of the aerial cell as shown in FIG. 5A and the terrestrial terminal 30 is located at the cell edge far from the base station of the terrestrial cell 100, the aerial antenna beam 202 directed from the base station 20 to the aerial terminal 40 and the terrestrial antenna beam 102 directed from the base station 20 to the terrestrial terminal 30 overlap as shown in FIG. 5B. This reduces the interference suppression effect achieved by beamforming, and beamforming cannot mutually suppress interference between the aerial cell 200 and the terrestrial cell 100, resulting in a deterioration in communication quality. Furthermore, in adaptive transmission power control that controls the transmission power of the terrestrial terminal 30 and the aerial terminal 40 to achieve a predetermined reception power, if the required reception power is set uniformly low for both the terrestrial terminal and the aerial terminal in order to suppress interference, the upper limit of communication quality (SNR) is limited, and high-speed transmission speeds (e.g., high-speed transmission speeds when a modulation method such as 64QAM or 256QAM is adopted) cannot be obtained.

[0038] In this embodiment, in order to more effectively reduce interference between terrestrial cells and airborne cells in the uplink, the above-mentioned adaptive transmission power control and the interference suppression weight (also called "interference cancellation weight") W Ｃ That is, the wireless communication system of this embodiment has an interference suppression system that uses the following interference reduction techniques (B1) to (B2) to reduce the interference in the uplink. (B1) Adaptive transmission power control is applied so that the received power from the ground terminal (e.g., ground terminal 30A) and the sky terminal (e.g., sky terminal 40A) of each base station (e.g., base station 20A) of the base station itself becomes a predetermined received power (required received power), but different values ​​can be set for the required received power. (B2) An interference suppression weight (interference removal weight) W is set for each base station (e.g., base station 20A). Ｃ Using this, interference suppression control (interference removal control) is applied to suppress interference between the received signal from the ground terminal (e.g., ground terminal 30A) for each base station and the received signal from the sky terminal (e.g., sky terminal 40A).

[0039] Fig. 6 is an explanatory diagram showing an example of the main configuration of a base station 20 in a wireless communication system according to an embodiment. The configuration example in Fig. 6 has an interference suppression system to which the above-mentioned adaptive beamforming, adaptive transmit power control, and adaptive interference suppression control are applied. Note that in Fig. 6, components common to those in Fig. 3 are assigned the same reference numerals, and descriptions thereof will be omitted.

[0040] 6, the wireless communication unit 23 provided in each base station device 21 of the base stations 20A to 20C has a transceiver 24, a terrestrial beam control unit 25-1 and an aerial beam control unit 25-2 provided to correspond to the terrestrial cell and the aerial cell, respectively, and an interference suppression unit 27. The terrestrial beam control unit 25-1 performs beamforming to direct a directional beam toward the terrestrial terminal 30. The aerial beam control unit 25-2 performs beamforming to direct a directional beam toward the aerial terminal 40 device.

[0041] The terrestrial beam control unit 25-1 has a beam control device 251-1 and an antenna weight application unit 252-1. The beam control device 251-1 calculates the values ​​to be set for the amplitude and phase of the received signal and the transmitted signal of each of the multiple antenna elements 261(1) to 261(3) of the antenna (for example, a massive antenna) 26, and calculates the "antenna beam forming weight (BF weight) w ＢＤ (w ｄ１ , w ｄ２ , w ｄ３ )) and the antenna weight application unit 252-1 calculates the BF weight w ＢＤ It is a device that sets the

[0042] The sky beam control unit 25-2 has a beam control device 251-2 and an antenna weight application unit 252-2. The beam control device 251-2 calculates the values ​​to be set for the amplitude and phase of the received signal and the transmitted signal of each of the multiple antenna elements 261(1) to 261(3) of the antenna (massive antenna) 26, and calculates the "antenna beam forming weight (BF weight) w ＢＵ (w Ｕ１ , w Ｕ２ , w Ｕ３ )) and the antenna weight application unit 252-2 calculates the BF weight wＢＵ It is a device that sets the

[0043] 7 is an explanatory diagram showing an example of the basic configuration of an interference suppression system that applies uplink interference suppression processing in a wireless communication system according to an embodiment. In FIG. 7, solid arrows indicate the flow of signals transmitted from the airborne terminal 40, and dashed arrows indicate the flow of signals transmitted from the ground terminal 30 (the same applies to FIGS. 8, 11, 13, and 16 described below).

[0044] In FIG. 7, the transmission signals S transmitted from the sky terminal 40 and the ground terminal 30 are １ , S ２ is propagated as a propagation path matrix H shown in the propagation path 60, and a received signal X including interference signals from other cells is expressed as １ , X ２ and input to the interference suppression unit 27.

[0045] The interference suppression unit 27 calculates the interference suppression weight W Ｃ is superimposed, and a received signal X after interference suppression expressed by the received signal matrix of the following equation (3) is output.

[0046] Here, the interference suppression weight W Ｃ is determined so as to become a diagonal matrix when multiplied by the channel matrix H as shown in the following equation (4). Ｃ For example, weights based on the ZF (zero forcing) standard, weights based on the MMSE (minimization of mean square error) standard, weights based on the block diagonalization method (BD method), etc. can be used as the weights.

[0047] When the received signal X after interference suppression shown in the above equation (3) is input to the transceiver 24, the transmitted signals S transmitted from the sky terminal 40 and the ground terminal 30 are １ , S ２ are output from the transceiver 24 as received signals that are free from mutual interference.

[0048] Fig. 8 is an explanatory diagram showing an example of the configuration of an interference suppression system according to an embodiment. In Fig. 8, components common to those in Fig. 7 are assigned the same reference numerals, and their description will be omitted. The interference suppression system of Fig. 8 includes a base station antenna BF control unit 25 and an interference suppression unit 27 provided in a base station 20. Transmission signals transmitted from an airborne terminal 40 and a ground terminal 30 propagate as a propagation path matrix H indicated by a propagation path 60, and are received as reception signals including interference signals of other cells as shown in the above-mentioned equation (1).

[0049] The received signal at the base station 20 is subjected to beamforming weight W Ｂ is superimposed, and furthermore, the interference suppression weight W Ｃ is superimposed, and the interference-suppressed received signal X shown in the received signal matrix of the following equation (5) is input to the transceiver 24.

[0050] When the received signal X after interference suppression shown in the above equation (5) is input to the transceiver 24, the transmitted signals S transmitted from the sky terminal 40 and the ground terminal 30 are １ , S ２ are output from the transceiver 24 as received signals that are free from mutual interference.

[0051] 8, a certain amount of interference between the ground terminal 30 and the sky terminal 40 is eliminated by beamforming in the base station antenna BF control unit 25. Furthermore, interference between the ground terminal 30 and the sky terminal 40 that cannot be eliminated by beamforming is eliminated by interference suppression processing (interference elimination function) in the interference suppression unit 27. In this way, the combination of beamforming and the interference elimination function makes it possible to significantly suppress interference between the ground terminal 30 and the sky terminal 40 in the uplink of the base station 20.

[0052] As shown in Figure 9A, when an aerial terminal 40 is located at a low altitude in an aerial cell and a terrestrial terminal 30 is located at a cell edge far from the base station of a terrestrial cell 100, an aerial antenna beam 202 directed from the base station 20 to the aerial terminal 40 and a terrestrial antenna beam 102 directed from the base station 20 to the terrestrial terminal 30 overlap as shown in Figure 9B. In this case, unless the combination of beamforming and interference suppression processing (interference removal function) in Figure 8 is applied, interference will occur between the aerial cell 200 and the terrestrial cell 100 in the uplink.

[0053] On the other hand, when the aerial terminal 40 is located at a low altitude in the aerial cell and the terrestrial terminal 30 is located at the cell edge far from the base station of the terrestrial cell 100 as shown in Figure 10A, by applying a combination of the beamforming of Figure 8 and the interference suppression processing (interference removal function), beam nulls are formed in the aerial antenna beam 202 directed from the base station 20 to the aerial terminal 40 and the terrestrial antenna beam 102 directed from the base station 20 to the terrestrial terminal 30 as shown in Figure 10B. That is, a null is formed in the aerial antenna beam 202 in the direction toward the terrestrial terminal 30, and a null is formed in the terrestrial antenna beam 102 in the direction toward the aerial terminal 40. By forming nulls in the aerial antenna beam 202 and the terrestrial antenna beam 102 in this way, interference between the aerial cell 200 and the terrestrial cell 100 in the uplink can be significantly suppressed.

[0054] Fig. 11 is an explanatory diagram showing another example of the configuration of the interference suppression system according to the embodiment. In Fig. 11, components common to Figs. 7 and 8 are assigned the same reference numerals, and their description will be omitted. The interference suppression system of Fig. 11 includes a base station antenna BF control unit 25 and an interference suppression unit 27 provided in the base station 20, and transmission power control units 410 and 320 provided in the terminal devices (air terminal 40, ground terminal 30). In the air terminal 40 and the ground terminal 30, respectively, the transmission power control units 410 and 320 control a predetermined transmission power control weight W Ｐ are superimposed and transmitted. The transmission power control weight W ＰThe transmitted signal superimposed with is propagated as a propagation path matrix H shown in propagation path 60, and is received as a received signal including interference signals from other cells as shown in the above-mentioned equation (1).

[0055] The received signal at the base station 20 is subjected to beamforming weight W Ｂ is superimposed, and furthermore, the interference suppression weight W Ｃ is superimposed, and the interference-suppressed received signal X shown in the received signal matrix of the following equation (6) is input to the transceiver 24.

[0056] When the received signal X after interference suppression shown in the above equation (6) is input to the transceiver 24, the transmitted signals S transmitted from the sky terminal 40 and the ground terminal 30 are １ , S ２ are output from the transceiver 24 as received signals that are free from mutual interference.

[0057] In the interference suppression system of Figure 11, as in the interference suppression system of Figure 8 described above, the combination of beamforming and interference removal function makes it possible to significantly suppress interference between the ground terminal 30 and the airborne terminal 40 on the uplink of the base station 20.

[0058] Furthermore, in the interference suppression system of Figure 11, as a technology for reducing interference between terrestrial cells and aerial cells, adaptive transmission power control is applied to the terrestrial terminal 30 and the aerial terminal 40 so that the received power of the uplink from the terrestrial terminal 30 and the aerial terminal 40 at the base station 20 becomes a predetermined received power (required received power), respectively.

[0059] In FIG. 11, transmission power control units 410 and 320 provided in the airborne terminal 40 and the ground terminal 30 respectively perform adaptive transmission power control based on transmission power control information received from the base station 20 .

[0060] In the adaptive transmission power control, the ground terminal 30 and the air terminal 40 generally have the same required reception power Γ as shown in FIG. 12A. Ｄ , Γ Ｕ Here, the required reception power of the ground terminal 30 is set as Γ Ｄ and the required reception power of the sky terminal 40 is ΓＵ In this embodiment, the required reception power Γ for adaptive transmission power control of each of the ground terminal 30 and the air terminal 40 is set according to the amount of interference removal assumed by the combination of beamforming and the interference removal function. Ｄ , Γ Ｕ By appropriately changing the above, the communication quality (communication capacity) of each of the ground terminal 30 and the air terminal 40 can be improved.

[0061] In particular, in this embodiment, the required reception power Γ for adaptive transmission power control of the sky terminal 40 is Ｕ By appropriately changing the above, the communication quality (communication capacity) of the airborne terminal 40 can be improved. Since the airborne terminal 40 is within line of sight of the base station 20, the received power (SNR) at the base station 20 becomes very large. Therefore, multi-level modulation (for example, 7-bit transmission (128QAM) to 10-bit transmission (1024QAM)) can be used, enabling high-speed transmission. However, since interference with the ground terminal 30 in the base station 20's own cell increases, it is necessary to significantly reduce the transmission power of the airborne terminal 40, and therefore the required received power Γ Ｕ Therefore, only low-bit-rate multi-level modulation (for example, 4-bit transmission (16QAM)) can be applied to the airborne terminal 40.

[0062] In this embodiment, the ground terminal 30 can eliminate interference from the sky terminal 40 by combining the beamforming and interference removal function, so there is no need to significantly reduce the reception power of the sky terminal 40. Therefore, as shown in FIG. 12B, the required reception power Γ of the sky terminal 40 is Ｕ For example, if the interference cancellation amount is set to 10 dB, the required received power Γ Ｕ Since the modulation can be increased by 10 dB, it becomes possible to apply high-bit-rate multi-level modulation (for example, 7-bit transmission (128QAM) to 10-bit transmission (1024QAM)) instead of low-bit-rate multi-level modulation (for example, 4-bit transmission (16QAM)), thereby enabling high-speed transmission.

[0063] In the interference suppression system of FIG. 11, the base station 20 estimates the amount of interference suppression by the interference suppression unit 27 for the ground terminal 30 and the sky terminal 40, and calculates the required reception power Γ for each terminal device according to the amount of interference suppression. Ｄ , Γ Ｕ For example, the base station 20 estimates the amount of interference suppression by the interference suppression unit 27 for each of the ground terminal 30 and the sky terminal 40, and sets the required reception power Γ for the ground terminal 30 and the sky terminal 40 according to the amount of interference suppression. Ｄ , Γ Ｕ In this case, Γ Ｄ , Γ Ｕ The values ​​of Γ and Γ may be the same or different. Ｄ , Γ Ｕ The setting of the (transmission power threshold) may be performed by an interference suppression control unit, which will be described later.

[0064] The received power at the base station of the airborne terminal and the ground terminal is the required received power Γ Ｄ , Γ Ｕ For example, when the transmission power is 100 dB, the reception power of the terminal is 50 dB, and the required reception power Γ Ｄ is 30 dB, the received power is 50 dB - 30 dB = 20 dB higher, and the transmitted power is also higher by that amount. Therefore, the transmitted power is controlled to account for this difference of 20 dB, and the transmitted power is set to 80 dB (= 100 dB - 20 dB).

[0065] Fig. 13 is an explanatory diagram showing another example of the configuration of an interference suppression system to which interference suppression processing in a wireless communication system according to an embodiment is applied. Note that in Fig. 13, components common to Figs. 7, 8, and 11 are assigned the same reference numerals, and descriptions thereof will be omitted. Also, in Fig. 13, the solid line and dashed line consisting of thick left-pointing arrows indicate the flow of desired signals received from the sky terminal 40 and the ground terminal 30, respectively, and the thin line and dashed line consisting of thin left-pointing arrows indicate the flow of interference signals received from the sky terminal 40 and the ground terminal 30, respectively (the same applies to Fig. 16 described below).

[0066] In the interference suppression system of Figure 13, if interference can be sufficiently suppressed using base station antenna adaptive beamforming alone due to the relationship between the position of the same base station 20 and the positions of the ground terminal 30 and the airborne terminal 40, the interference suppression process is not enabled, and the amount of signal processing related to the interference suppression process is reduced.

[0067] 13, the base station 20 includes a branching unit 28 that branches an intermediate signal of the received signal output from the base station antenna BF control unit 25, and an interference suppression control unit 29 that switches on / off the interference suppression function of superimposing an interference suppression weight Wc in the interference suppression unit 27. The interference suppression control unit 29 measures the received power (power of a desired signal) and interference power (power of an interference signal) for each of the ground terminal 30 and the sky terminal 40 at the same base station 20 when base station antenna adaptive beamforming is applied to the uplink, based on the intermediate signal of the received signal branched by the branching unit 28, and calculates the communication quality (SINR) λ of the received signal of the uplink for each of the ground terminal 30 and the sky terminal 40. Ｄ , λ Ｕ is estimated (S291).

[0068] Next, the interference suppression control unit 29 calculates the communication quality (SINR) λ of the received signals of the uplinks of the ground terminal 30 and the sky terminal 40. Ｄ , λ Ｕ Based on the estimation results, the communication quality (SINR) λ of each of the ground terminal 30 and the air terminal 40 is calculated. Ｄ , λ Ｕ 13, the interference suppression control unit 29 determines whether the communication quality (SINR) λ of each of the ground terminal 30 and the air terminal 40 satisfies a predetermined condition (S292). Ｄ , λ Ｕ Here, it is determined whether the communication quality (SINR) λ of the ground terminal 30 and the sky terminal 40 is equal to or greater than a predetermined threshold (hereinafter also referred to as a "required value") Λ. Ｄ , λ Ｕ are both greater than or equal to the threshold (required value) Λ (λ Ｄ , λ Ｕ ≧Λ), the interference suppression unit 27 is controlled to turn off the interference suppression process (interference removal process function).

[0069] The ON / OFF of the interference suppression processing (interference removal processing function) is determined by the interference suppression weight (interference removal weight) W superimposed on the received signal matrix in the interference suppression unit 27. Ｃ For example, the interference suppression weight W Ｃ By setting the value to ON, the interference suppression processing (interference removal processing function) is turned ON, and the interference suppression weight W Ｃ By setting the value to 0, the interference suppression processing (interference removal processing function) can be turned off.

[0070] For example, when an aerial terminal 40 is located at a high altitude in an aerial cell and a terrestrial terminal 30 is located inside a terrestrial cell 100 as shown in FIG. 14A, there is no overlap between an aerial antenna beam 202 directed from the base station 20 to the aerial terminal 40 and a terrestrial antenna beam 102 directed from the base station 20 to the terrestrial terminal 30 as shown in FIG. 14B, depending on the beam width of the base station array antenna 26. In this case, the interference between the aerial cell 200 and the terrestrial cell 100 is small, and the interference is small within a predetermined condition (λ Ｄ ≧Λ AND λ Ｕ ≧Λ) is satisfied, and the interference suppression processing (interference removal processing function) in the interference suppressor 27 is turned off.

[0071] On the other hand, when the aerial terminal 40 is located at a low altitude of the aerial cell as shown in Fig. 15A and the terrestrial terminal 30 is located at the cell edge far from the base station of the terrestrial cell 100, the aerial antenna beam 202 directed from the base station 20 to the aerial terminal 40 and the terrestrial antenna beam 102 directed from the base station 20 to the terrestrial terminal 30 overlap as shown in Fig. 15B depending on the beam width of the base station array antenna 26. In this case, the interference between the aerial cell 200 and the terrestrial cell 100 is large, and the interference does not exceed a predetermined condition (λ Ｄ ≧Λ AND λ Ｕ ≧Λ) is not satisfied, that is, the condition for interference occurrence (λ Ｄ <Λ OR λ Ｕ<Λ) is determined to be satisfied, and the interference suppression processing (interference removal processing function) in the interference suppression unit 27 is turned ON. By turning ON the interference suppression processing, beam nulls are formed in the aerial antenna beam 202 directed from the base station 20 to the aerial terminal 40 and the terrestrial antenna beam 102 directed from the base station 20 to the terrestrial terminal 30 in mutual directions, and as shown in FIG. 15C, the interference between the aerial cell 200 and the terrestrial cell 100 is reduced, and the predetermined condition (λ Ｄ ≧Λ AND λ Ｕ ≧Λ).

[0072] 16 is an explanatory diagram showing yet another example of the configuration of an interference suppression system to which interference suppression processing is applied in a wireless communication system according to an embodiment. In the interference suppression system of FIG. 16 , if interference can be sufficiently suppressed by base station antenna adaptive beamforming alone due to the relationship between the position of the same base station 20 and the positions of the ground terminal 30 and the airborne terminal 40, the interference suppression processing is not enabled and the amount of signal processing related to the interference suppression processing is reduced.

[0073] In Figure 16, the interference suppression control unit 29 determines whether to apply an interference canceller, i.e., whether to turn on or off the interference suppression processing (interference removal processing function) in the interference suppression unit 27, depending on the positions (distance from the base station 20, altitude) of the airborne terminal 40 and the ground terminal 30.

[0074] Generally, the direction (θ Ｕ ) and the direction of the ground terminal 30 (θ Ｄ ) and the angle difference (|θ Ｄ -θ Ｕ |) is large, the base station antenna adaptive beamforming can sufficiently suppress interference.

[0075] Here, as shown in FIG. 17A, the angle θ Ｕ is the angle θ of the direction of the sky terminal 40, which is the angle upward when viewed from the position of the antenna 26 of the base station 20 toward the sky terminal 40, with the horizontal line passing through the position of the antenna 26 of the base station 20 in the figure as the reference (0°). ＵThe downward angle when looking from the position of the antenna 26 of the base station 20 toward the ground terminal 30 is the angle θ Ｕ is.

[0076] In the interference suppression system of FIG. 16, the interference suppression control unit 29 detects the angle θ Ｕ and the angle θ of the direction of the ground terminal 30 Ｄ and the angular difference between the directions of the ground terminal 30 and the sky terminal 40 (|θ Ｄ -θ Ｕ 16, the interference suppression control unit 29 determines whether the angular difference (|θ Ｄ -θ Ｕ |) is a predetermined threshold Γ θ Here, it is determined whether the angle difference (|θ Ｄ -θ Ｕ |) is the threshold Γ θ or more (|θ Ｄ -θ Ｕ |≧Γ θ ) (see FIG. 17B), the interference suppression processing (interference removal processing function) in the interference suppression unit 27 is turned off, and the angle difference (|θ Ｄ -θ Ｕ |) is the threshold Γ θ Less than (|θ Ｄ -θ Ｕ |<Γ θ ), the interference suppression unit 27 is controlled to turn on the interference suppression process (interference removal process function).

[0077] In particular, in the interference suppression system of FIG. 16, the angle of the direction of the sky terminal 40 (θ Ｕ ) and the angle (θ Ｄ ) information alone can easily turn the interference suppression function on and off.

[0078] 18A and 18B are explanatory diagrams illustrating an example of selection of an optimal directional beam directed from the antenna of the base station 20 to a terminal device (e.g., a ground terminal 30 in the illustrated example) in a wireless communication system according to an embodiment. In this embodiment, for example, multiple (five in the illustrated example) directional beam candidates that can be formed by the antenna 26 of the base station 20 and that are oriented in different vertical planes are set in advance, and information on the directional beam candidates is shared between the base station 20 and the terminal devices (the ground terminal 30 and the airborne terminal 40). The optimal directional beam is selected depending on the direction of the terminal devices (the ground terminal 30 and the airborne terminal 40) as seen from the antenna 26 of the base station 20. For example, the terminal devices (the ground terminal 30 and the airborne terminal 40) receive signals transmitted from the base station 20 using the multiple directional beams, measure the received power, select the directional beam with the largest measured received power, and notify the base station 20 of information on the selected directional beam (e.g., a beam identification number). The base station 20 communicates with the terminal devices (ground terminal 30, air terminal 40) using the selected directional beam.

[0079] 18A, when the ground terminal 30 is located far away from the antenna 26 of the base station 20, the ground terminal 30 selects the fourth directional beam 102(4) from the top, which has the highest measured received power, and notifies the base station 20 of the beam identification number of the selected directional beam 102(4). The base station 20 communicates with the ground terminal 30 using the selected fourth directional beam 102(4).

[0080] 18B , when the ground terminal 30 is located near the antenna 26 of the base station 20, the ground terminal 30 selects the fifth directional beam 102(5) from the top, which has the highest measured received power, and notifies the base station 20 of the beam identification number of the selected directional beam 102(5). The base station 20 communicates with the ground terminal 30 using the selected fifth directional beam 102(5).

[0081] As described above, according to this embodiment, in a three-dimensional spatial cell configuration in which the ground cell 100 and the air cell 200 share the same frequency band, interference between the received signal received by the base station 20 from the ground terminal 30 and the received signal received from the air terminal 40 can be suppressed.

[0082] In addition, a machine-learned model created by machine learning may be used for the calculation of weights in this embodiment.

[0083] This invention makes it possible to construct a three-dimensional spatial cell configuration that enables terrestrial cells and aerial cells to share the same frequency band, 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 build resilient technological infrastructure."

[0084] It should be noted that the process steps and components of the wireless communication system described herein may be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof.

[0085] For hardware implementation, means such as processing units used to implement the steps and components in an entity (e.g., various wireless communication devices, transceivers, transmitters, receivers, base station devices, e-NodeBs, g-NodeBs, terminal devices, hard disk drive devices, or optical disk drive devices) 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.

[0086] Furthermore, with regard to firmware and / or software implementations, each unit used to realize the components may be implemented as a program (e.g., code, such as procedures, functions, modules, instructions, etc.) that performs the functions described herein. In general, any computer / processor-readable medium tangibly embodying firmware and / or software code may be used to implement means, such as a processing unit, used to realize the steps and components described herein. For example, the firmware and / or software code may be stored in memory, such as in a control device or storage device, and executed by a computer or processor. The memory may be implemented within the computer or processor, or external to the processor. The firmware and / or software code may also be stored on a computer or processor readable medium such as, for example, 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.

[0087] 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.

[0088] 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.

[0089] 10: Wireless communication system 20A to 20C: Base station 21: Base station device 23: Wireless communication unit 26: Antenna 261: Antenna element 23: Wireless communication unit 24: Transceiver 25: Base station antenna BF control unit (beam control unit) 26: Antenna 261: Antenna element 27: Interference suppression unit 28: Branching unit 29: Interference suppression control unit 30, 30A to 30C: Terminal device (terrestrial terminal) 40, 40A to 40C: Terminal device (air terminal) 60: Propagation path 100, 100A to 100C: Terrestrial cell 102: Terrestrial antenna beam 200, 200A to 200C: Air cell 202: Air antenna beam 251: Beam control device 252: Antenna weight application unit 261: Antenna element 320: Transmission power control unit 410: Transmission power control unit A1: Ground service area A2: Sky service area

Claims

1. A wireless communication system comprising one or more base stations, wherein the base station comprises: an antenna capable of forming a plurality of mutually different directional beams; a wireless communication unit that forms terrestrial cells and aerial cells separately using the same frequency band, and performs wireless communication via the antenna between a terrestrial terminal device located in the terrestrial cell and an aerial terminal device located in the aerial cell; a terrestrial beam control unit that performs beamforming to direct a directional beam toward the terrestrial terminal device; an aerial beam control unit that performs beamforming to direct a directional beam toward the aerial terminal device; and an interference suppression unit that superimposes an interference suppression weight that suppresses interference signals from the aerial terminal device on a received signal received from the terrestrial terminal device via the antenna, and superimposes an interference suppression weight that suppresses interference signals from the terrestrial terminal device on a received signal received from the aerial terminal device via the antenna.

2. A radio communication system according to claim 1, wherein the ground terminal device and the air terminal device are equipped with a transmission power control unit that controls transmission power to the base station based on transmission power control information received from the base station, and the base station estimates the amount of interference suppression for the ground terminal device and the air terminal device in the interference suppression unit, sets the required reception power for the ground terminal device and the air terminal device according to the estimated amount of interference suppression, determines the amount of transmission power for the ground terminal device and the air terminal device according to the set required reception power, and transmits the determined amount of transmission power to the ground terminal device and the air terminal device as the transmission power control information.

3. A wireless communication system according to claim 1 or 2, characterized in that the base station comprises an interference suppression control unit that estimates the communication quality of the received signal received from the ground terminal device and the communication quality of the received signal received from the airborne terminal device, and switches on / off the interference suppression function of the interference suppression unit that superimposes the interference suppression weight based on the result of the communication quality estimation.

4. A wireless communication system according to claim 1 or 2, characterized in that the base station is provided with an interference suppression control unit that estimates an angular difference between the direction of the ground terminal device and the direction of the airborne terminal device based on the position of the antenna, and switches on / off an interference suppression function in the interference suppression unit that superimposes the interference suppression weight based on the estimated angular difference. A wireless communication system is provided that can suppress interference between signals received by a base station from a terrestrial terminal and signals received from an aerial terminal in a three-dimensional spatial cell configuration that realizes sharing of the same frequency band between terrestrial cells and aerial cells.

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