JP2020072417A - Mobile station, flight vehicle and mobile communication system - Google Patents

Abstract

To suppress interference between cells of a down link and an up link between a large zone cell and a ground cell by an antenna of a mobile station between a communication relay device forming the large zone and a base station at a low altitude when the mobile station is positioned therebetween, and enable simultaneous connection to the large zone cell and the cell formed by the base station at a low altitude while enlarging frequency utilization efficiency.SOLUTION: The mobile station is used under such a state as to be positioned between a communication relay device forming a large zone cell and a base station at a low altitude, and includes a first antenna with a more upward directional beam than the horizontal direction and a second antenna with a more downward directional beam than the horizontal direction among a plurality of antennas used in the identical frequency band, and a radio communication section performing radio communication with the communication relay device of the large zone cell through the first antenna and performing radio communication with the base station at a low altitude through the second antenna by the same frequency band.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mobile station, and an aircraft and a mobile communication system including the mobile station.

  In recent years, as a measure against disasters and out-of-range resolution, we have been moving from a communication relay device that is movable by being incorporated in an aircraft (floating body) such as an aircraft, an artificial satellite, a HAPS, a balloon, and a drone to the ground, water or low altitude in the air. The development of three-dimensional large zone cells formed by the above is effective. In an overlay cell configuration in which a terrestrial cell formed by a terrestrial cell base station such as a macro cell base station is superposed in this large zone cell, by operating the large zone cell by using the same frequency band as the terrestrial cell, frequency utilization efficiency can be improved. Can be expanded.

  In the overlay cell configuration, when the mobile station is located between the communication relay device of the large zone cell and the terrestrial cell base station, by the antenna of the mobile station, one of the communication relay device of the large zone cell and the terrestrial cell base station, or If wireless communication in the same frequency band is performed between the both, there is a possibility that downlink and uplink inter-cell interference between the large zone cell and the ground cell may occur.

  Patent Document 1 includes a receiving antenna that receives a radio wave coming from a base station, and a power measuring unit that measures the power of the received radio wave, and the radio wave is moved to a predetermined position a predetermined distance away from the base station. There is disclosed a drone that is rotated so that the direction of arrival and the direction of the receiving antenna correspond to each other. According to Patent Document 1, the electric power of the radio wave radiated from the base station to the space can be measured with high accuracy at all points on the radiation surface.

JP, 2008-096928, A

  In the above conventional overlay cell configuration, in a mobile station incorporated in a drone or the like located at a high altitude between a communication relay device forming a large zone cell and a ground cell base station, the mobile station has an omnidirectional antenna. In this case, due to the interference between cells in the same frequency band, radio communication cannot be performed with either or both of the large zone cell and the terrestrial cell, or the communication quality is significantly deteriorated. When the mobile station has a directional antenna, the mobile station can communicate with only a large zone cell or a ground cell unless the drone rotates due to the directivity of the antenna of the mobile station. Further, in the case where the drone of the above Patent Document 1 rotates so that the arrival direction of the radio wave from the base station and the direction of the receiving antenna correspond to each other, the communication between the large zone cell communication relay device and the ground cell base station is performed. In order to suppress interference between cells in the same frequency band and perform wireless communication, the drone needs to be rotated, and it is not possible to connect to the large zone cell and the ground cell at the same time for wireless communication.

  A mobile station of a mobile communication system according to an aspect of the present invention is used in a state of being located between a communication relay device forming a large zone cell and a low-altitude base station located at an altitude lower than the communication relay device. A plurality of antennas used in the same frequency band, the first antenna having a directional beam upward from the horizontal direction and the second antenna having a directional beam downward from the horizontal direction; And a wireless communication unit that wirelessly communicates with the communication relay device of the large zone cell via a first antenna and wirelessly communicates with the low altitude base station via the second antenna.

When the mobile station preferentially selects wireless communication via a communication line with the low altitude base station, and when the communication quality of the wireless communication with the low altitude base station deteriorates, or When wireless communication with a low-altitude base station is disconnected, a communication line is established between the large-zone cell communication relay device and the communication connection destination from the low-altitude base station to the large-zone cell communication relay device. A switching control unit for switching to may be provided.
In the mobile station, when the wireless communication via the communication line with the communication relay device of the large zone cell is selected, the communication quality of the wireless communication with the low altitude base station is a predetermined threshold value. When the above is reached, a communication line with the low altitude base station may be established, and the communication connection destination may be switched from the communication relay device of the large zone cell to the low altitude base station.

In the mobile station, a communication line is established between each of the low-altitude base station and the communication relay device of the large zone cell, and wireless communication is performed via the communication line with the low-altitude base station. Select preferentially, when the communication quality of the wireless communication with the low altitude base station deteriorates or when the wireless communication with the low altitude base station is disconnected, the communication connection destination of the low altitude A switching control unit for switching from the base station to the communication relay device of the large zone cell may be provided.
In the mobile station, when the wireless communication via the communication line with the communication relay device of the large zone cell is selected, the communication quality of the wireless communication with the low altitude base station is a predetermined threshold value. When the above is reached, the communication connection destination may be switched from the communication relay device of the large zone cell to the low altitude base station, and a communication line may be maintained between the communication relay device of the large zone cell.

In the mobile station, preferentially selects wireless communication via a communication line with the low-altitude base station, and using the position information of the mobile station, the mobile station is a low-altitude base station and Determine whether it is located inside or outside the communicable three-dimensional area, and when the mobile station moves out of the three-dimensional area, establish a communication line with the communication relay device of the large zone cell. A switching control unit that switches the communication connection destination from the low-altitude base station to the communication relay device of the large zone cell may be provided.
In the mobile station, when the wireless communication via the communication line with the communication relay device of the large zone cell is selected, the location information of the mobile station is used to make the mobile station the low altitude base. Determine whether it is located in or outside the three-dimensional area capable of communicating with the station, when the mobile station moves into the three-dimensional area, establish a communication line with the low altitude base station, The communication connection destination may be switched from the communication relay device of the large zone cell to the low altitude base station.
In the mobile station, a communication line is established between each of the low-altitude base station and the communication relay device of the large zone cell, and wireless communication is performed via the communication line with the low-altitude base station. Performing with priority, using the position information of the mobile station, to determine whether the mobile station is located in or outside the three-dimensional area that can communicate with the low-altitude base station, the mobile station A switching control unit may be provided for switching the communication connection destination from the low-altitude base station to the communication relay device of the large zone cell when moving outside the three-dimensional area.
In the mobile station, when the wireless communication via the communication line with the communication relay device of the large zone cell is selected, the location information of the mobile station is used to make the mobile station the low altitude base. It is determined whether the mobile station is located inside or outside the three-dimensional area of the station, and when the mobile station moves into the three-dimensional area, the communication connection destination is from the communication relay device of the large zone cell to the low altitude base. It is also possible to switch to a station and maintain a communication line with the communication relay device of the large zone cell.
The mobile station may include a position detection unit that detects the current position of the mobile station using a GNSS (Global Navigation Satellite System).

The mobile station may be provided on a movable body in a space between the low altitude base station and the communication relay device of the large zone cell.
The aircraft is located in the space between the low-altitude base station and the communication relay device of the large zone cell, by self-sustaining control or external control, or by the operation of an operator on the aircraft. You may control.
The air vehicle may be a drone, airship, balloon, aircraft, helicopter or HAPS.

  The low-altitude base station may be a base station that forms a macro cell or a small cell on the ground or on the sea, and the communication relay device of the large zone cell has a cell size on the ground or on the sea from the macro cell and the small cell. May be a large zone cell base station forming a large large zone cell.

  An aircraft according to another aspect of the present invention is an aircraft including any one of the mobile stations described above. In the air vehicle, so as to be located in the space between the low altitude base station and the communication relay device of the large zone cell, by self-sustaining control or control from the outside, or by the operation of the operator who boarded the air vehicle. It may be controlled.

  A communication system according to still another aspect of the present invention is located at a higher altitude than any one of the mobile stations, a low altitude base station capable of wireless communication with the mobile station, and the low altitude base station. , A low-altitude base station capable of wirelessly communicating with the mobile station.

  According to the present invention, when a mobile station is located between a communication relay device of a large zone cell and a base station of a lower altitude lower than the communication relay device, the antenna of the mobile station causes the large zone cell and the ground cell to It is possible to suppress the inter-cell interference between the downlink and the uplink between the two, and simultaneously connect with the large zone cell and the cell formed by the low-altitude base station while expanding the frequency utilization efficiency.

FIG. 3 is an explanatory diagram showing an example of a schematic configuration of a mobile communication system having an overlay cell configuration in which a plurality of ground cells are arranged in a large zone cell according to the embodiment of the present invention. Explanatory drawing which shows the example of the inter-cell interference in a downlink when UE is located in the space between the relay communication station of a large zone cell, and the terrestrial cell base station. Explanatory drawing which shows the example of the inter-cell interference in an uplink when UE is located in the space between the relay communication station of a large zone cell, and the terrestrial cell base station. The block diagram which shows an example of the principal part structure of UE which concerns on this embodiment. The block diagram which shows the other example of the principal part structure of UE which concerns on this embodiment. The flowchart which shows an example of the cell switching control in UE which concerns on this embodiment. The flowchart which shows the other example of the cell switching control in UE which concerns on this embodiment. The flowchart which shows the further another example of the cell switching control in UE which concerns on this embodiment. The flowchart which shows the further another example of the cell switching control in UE which concerns on this embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an explanatory diagram showing an example of a schematic configuration of a mobile communication system having an overlay cell configuration in which a terrestrial cell 10A that is a plurality of low altitude base stations is arranged in a large zone cell 15A according to an embodiment of the present invention. is there. As a measure against a disaster or out-of-range resolution, a large-sized large zone cell 15A formed from the aerial levitation type communication relay device 15 in which a relay communication station 150 is incorporated into a flying body that can move above the ground or above water is used. Deployment is effective. Further, as a measure against the traffic of mobile communication that rapidly increases in the large zone cell 15A, it is effective to apply an overlay cell configuration in which a plurality of ground cells 10A are superposed in the large zone cell 15A. In this overlay cell configuration, the frequency utilization efficiency can be expanded by using the same frequency band (f0) between the large zone cell 15A and the terrestrial cell 10A, and the user terminal device (hereinafter also referred to as “UE”) that is a mobile station. It is possible to increase the communication quality (for example, throughput) in 30, 31, 35.

  In FIG. 1, the mobile communication system of the present embodiment is a communication system complying with next-generation standard specifications such as LTE (Long Term Evolution) / LTE-Advanced or the fifth generation, and via a terrestrial cellular base station. It is a mobile communication system in which a terrestrial system (a terrestrial cellular mobile communication system) and a communication system via an aerial levitation type communication relay device are mixed.

  The mobile communication system according to the present embodiment includes a relay communication station 150 mounted in an aerial levitation type communication relay device 15 that can move over the atmosphere or outside the atmosphere, and a cell that is a wireless communication area of the relay communication station 150. (Hereinafter, referred to as “large zone cell”.) A ground cell base station 10 as a plurality of low altitude base stations fixedly arranged in 15A is provided.

  The low-altitude base station is a base station located at a lower altitude than the relay communication station 150 of the communication relay device 15, and is a ground cell base station placed on the ground, or a base station installed on the water, It may be a base station provided in a drone, a balloon, or the like located at a lower altitude than the relay communication station 150.

  The relay communication station 150 is a repeater that relays wireless communication of the feeder link FL on the mobile communication network side and wireless communication of the service link SL on the UE (mobile station) side. The relay communication station 150 includes, for example, a feeder link FL antenna 151 and a service link SL antenna 152, and wireless communication of the feeder link FL (frequency: fc) and a service link SL (frequency: f0) on the UE (mobile station) side. ) And wireless communication can be relayed after frequency conversion.

  The frequency band of the service link SL is, for example, a frequency band selected from several hundred MHz, several GHz, tens GHz and the like.

  In addition, the mobile communication system of the present embodiment includes a large zone cell base station (e.g., eNodeB, gNodeB) 70 capable of wirelessly communicating with the UE 20 via the relay communication station 150 of the airborne communication relay device 15. The large zone cell base station 70 relays the levitation type communication relay device 15 via a gateway (GW) station 71 having a frequency conversion function for converting the frequency f0 on the mobile communication network side and the frequency fc of the feeder link FL. Communicate with the communication station 150.

  The large zone cell base station 70, the terrestrial cell base station (e.g., eNodeB, gNodeB) 10, and the central control server as a base station management device that manages each base station, respectively, are wired communication such as dedicated lines and general-purpose lines. It is connected to the core network of the mobile communication network via a line.

  The relay communication station 150 of the communication relay device 15 may be provided with the function of the large zone cell base station (e.g., eNodeB, gNodeB) 70. That is, the relay communication station 150 may have a function of a base station (e.g., eNodeB, gNodeB) instead of a function of a repeater.

  The terrestrial cell base station 10 is, for example, a normal macro cell base station or a small cell base station. A cell (hereinafter, appropriately referred to as “ground cell”) 10A that is a wireless communication area of the ground cell base station 10 is included inside the large zone cell 15A. The number of ground cells arranged in the large zone cell 15A may be 1 to 4 or 6 or more. Further, the first base station located in the large zone cell 15A may be a small cell base station forming a small cell smaller than the macro cell.

  Although FIG. 1 shows an example in which the communication relay device 15 equipped with the relay communication station 150 is an airship as a flying body that can move above, the communication relay device 15 flies so as to move above the sky. In addition to possible drones, balloons, aircraft, helicopters, solar plane type HAPS (“high altitude platform stations” or “high altitude pseudolites”), airship type HAPS, other unmanned or manned air vehicles such as artificial satellites. May be

  The flying object is located by flying in a high altitude air space of 100 [km] or less from the ground, the sea surface, or the water surface such as a river or a lake by the autonomous control, the control from the outside, or the operation of the pilot who gets on the flying object. May be controlled to do so. Further, the flight airspace of the air vehicle may be a stratospheric airspace having an altitude of 11 [km] or more and 50 [km] or less. Further, the flight airspace of the air vehicle may be an airspace having an altitude of 15 [km] or more and 25 [km] or less, in which the weather conditions are relatively stable, and particularly an airspace having an altitude of approximately 20 [km]. Good.

  Further, the relay communication station 150 of the large zone cell may be installed at a position higher than the ground cell base station 10 (including a position in the atmosphere and a position in outer space outside thereof).

  The terrestrial cell base station 10 is, for example, a normal macro cell base station or a small cell base station. The macrocell base station is a high-power base station that covers a terrestrial cell, which is a wide area with a radius of several hundred meters to several kilometers normally installed outdoors in a mobile communication network. The macrocell base station is connected to another base station by, for example, a wired communication line, and can communicate with a predetermined communication interface. Further, the macro cell base station is connected to the core network of the mobile communication network through a communication line such as a line terminating device and a dedicated line, and communicates with various nodes such as a server on the core network by a predetermined communication interface. It is possible. Unlike a wide-area macro cell base station, a small cell base station has a wireless communication range of several meters to several hundred meters, and can be installed inside a building such as a general home, a store, or an office. Is a base station. The small cell base station is also connected to the core network of the mobile communication network via a line terminating device and a communication line such as an ADSL (Asymmetric Digital Subscriber Line) line or a broadband public communication line such as an optical line, and on the core network. It is possible to communicate with various nodes such as a server device through a predetermined communication interface.

  The ground cell base station in the large zone cell 15A may be a base station installed on the ground or on the water, or may be a base station installed on a low-altitude flying vehicle such as a drone or a balloon.

  In FIG. 1, a UE 30, which is a first mobile station, is a user terminal device (MUE) that is located in the large zone cell 15A and connected to the relay communication station 150, and makes a telephone call or data communication via the relay communication station 150. For example, wireless communication is possible. Since the UE 30 is located near the boundary between the large zone cell 15A and the ground cell 10A, the UE 30 is in a situation where it is likely to be interfered with by the ground cell 10A.

  The UE 31, which is the second mobile station, is a user terminal device (SUE) located in the outer edge of the cell 10A of the terrestrial cell base station 10 and connected to the terrestrial cell base station 10, and It is in a state where it is possible to make a wireless communication via a telephone or data communication via. Since the UE 31 is located near the boundary between the terrestrial cell 10A and the large zone cell 15A, the UE 31 is likely to be interfered with by the large zone cell 15A.

  The UE 35, which is the third mobile station as the sky terminal, is a user terminal device used in a state of being located between the relay communication station 150 forming the large zone cell 15A and the ground cell base station 10. The UE 35 is provided in a flying body 40 that is movable in the space between the relay communication station 150 forming the large zone cell 15A and the ground cell base station 10.

  In the present embodiment, the flight vehicle 40 equipped with the UE 35 is a drone (unmanned flight vehicle). The air vehicle 40 may be an airship, a balloon, an aircraft, a helicopter, a solar plane type HAPS (“high altitude platform station” or “high altitude pseudolite”), or an airship type HAPS, in addition to a drone. The flight airspace of the air vehicle 40 equipped with the UE 35 is, for example, an airspace having an altitude of several tens [m] or more and a few [km] or less, and particularly an airspace having an altitude of 100 [m] or more and 1 [km] or less. May be.

  The UE 35 mounted on the air vehicle 40 is preferentially connected to the terrestrial cell base station 10 and is capable of wireless communication for telephone calls and data communication via the terrestrial cell base station 10. When the communication quality with the terrestrial cell base station 10 is deteriorated or the communication line with the terrestrial cell base station 10 is disconnected, the UE 35 is switched to the connection with the relay communication station 150 of the large zone cell 15A to perform relay communication. By establishing a communication line with the station 150, wireless communication for telephone calls, data communication, etc. is possible via the relay communication station 150 of the large zone cell 15A.

  When the UEs 30, 31, 35 are located in the large zone cell 15A or the terrestrial cell 10A, the UEs 30, 31, 35 communicate with a macro cell base station, a small cell base station, a large zone cell base station, or the like corresponding to the cell in which they are located, by a predetermined communication method. And wireless communication resources can be used for wireless communication. The UEs 30, 31, and 35 are configured by using hardware such as a computer device having a CPU and a memory, an external communication interface unit for the core network, a wireless communication unit, and the like, and the base station 10 is executed by executing a predetermined program. , Wireless communication with the relay communication station 150, the base station 70 and the like can be performed.

  Each of the UEs 30, 31, and 35 may include a position detection unit that detects the current position of the UE itself. The position detection unit receives signals from a plurality of artificial satellites by using, for example, a GNSS (Global Navigation Satellite System) such as GPS (Global Positioning System) and displays the current position (latitude, longitude, altitude) of the UE itself. A value may be calculated and detected.

  In the present embodiment, the relay communication station 150 of the large zone cell 15A, the large zone cell base station 70, and the terrestrial cell base station 10 are each, for example, a computer device having a CPU, a memory, etc., an external communication interface unit for the core network, a wireless communication unit, etc. It is possible to perform wireless communication with the UEs 30, 31, and 35 by using a predetermined communication method and a wireless communication resource by being configured by using the above hardware and executing a predetermined program.

  Each of the base stations 10 and 70 is a base station capable of performing downlink wireless communication of an OFDM (Orthogonal Frequency Division Multiplexing) system with respect to a UE that is a mobile station. The base stations 10 and 70 include, for example, an antenna, a radio signal path switching unit, a duplexer (DUP), a downlink radio receiving unit, an OFDM (Orthogonal Frequency Division Multiplexing) demodulating unit, an uplink radio receiving unit, and SC-FDMA ( Single-Carrier Frequency-Division Multiple Access) A demodulation unit etc. are provided. Further, each of the base stations 10 and 70 includes an OFDM modulator, a downlink radio transmitter, a controller and the like.

  The SC-FDMA demodulation unit performs SC-FDMA demodulation processing on the reception signal received by the uplink radio reception unit, and passes the demodulated data to the control unit. The OFDM modulator modulates the data of the downlink signal transmitted from the controller to the UE residing in the cell of the own station by the OFDM method so as to be transmitted with a predetermined power. Further, when the base station receives, for example, the information of the subframe of which transmission is to be stopped from the server, the OFDM modulation unit is controlled to stop the downlink transmission of only a specific subframe in the wireless communication frame. The downlink wireless transmission unit transmits the transmission signal modulated by the OFDM modulation unit via the duplexer, the wireless signal path switching unit and the antenna.

  The control unit of the base stations 10 and 70 is configured of, for example, a computer device, and controls and controls each unit and executes various processes by reading and executing a predetermined program.

2 and 3 are explanatory diagrams showing examples of inter-cell interference in the downlink and the uplink when the UE 35 is located in the space between the relay communication station 150 of the large zone cell 15A and the ground cell base station 10, respectively. is there.
In FIG. 2, when a downlink signal is transmitted from the relay communication station 150 of the large zone cell 15A to the UE 35 located in the large zone cell 15A, from the terrestrial cell base station 10 that uses the same frequency band as the large zone cell 15A. Interference may deteriorate the quality of the downlink signal received by the UE 35.
Further, in FIG. 3, when the uplink signal is transmitted from the UE 35 located in the large zone cell 15A to the relay communication station 150 of the large zone cell 15A, the uplink signal transmitted from the UE 35 corresponds to the large zone cell 15A. There is a risk of reaching and interfering with the terrestrial cell base station 10 that uses the same frequency band.

  Therefore, in the present embodiment, as shown in FIG. 1, in order to suppress the interference in the downlink and the uplink, the UE 35, which is a sky terminal, has the same frequency band (f0 having a directional beam upward than the horizontal direction). ) 351 (hereinafter referred to as “upward antenna”) 351 and a second antenna (hereinafter referred to as “downward antenna”) 352 for the same frequency band (f0) having a directional beam downward from the horizontal direction. Is provided. The UE 35 performs wireless communication with the relay communication station 150 of the large zone cell 15A via the upward antenna 351 and wireless communication with the ground cell base station 10 via the downward antenna 352. As a result, it is possible to simultaneously connect the large zone cell 15A and the ground cell 10A while increasing the frequency utilization efficiency, and it is possible to suppress inter-cell interference between the ground cell 10A and the large zone cell 15A.

  In addition, in the present embodiment, the beam width and the antenna gain of the directional beam of the upward antenna 351 may be changed according to the type of the communication relay device 15 in which the relay communication station 150 of the large zone cell 15A is mounted. For example, when the communication relay device 15 is an artificial satellite whose relative position with respect to the UE 35 is small, the beam width of the directional beam of the upward antenna 351 may be narrowed and the antenna gain may be increased. When the communication relay device 15 is HAPS in which the relative position change with respect to the UE 35 is large, the beam width of the directional beam of the upward antenna 351 may be widened and the antenna gain may be reduced.

  Further, in the present embodiment, the directional beam of the upward antenna 351 of the UE 35 may always be directed to the relay communication station 150 when the attitude of the UE 35 changes or the UE 35 moves. For example, the directional beam of the upward antenna 351 of the UE 35 is relayed based on the detection result of the attitude change of the UE 35 detected by the inertial sensor or the gravity sensor, the information of the position change of the UE 35 measured by the GNSS receiver, and the like. The upward antenna 351 may be mechanically or electrically controlled so as to follow the station 150.

  Further, in the present embodiment, when the communication relay device 15 equipped with the relay communication station 150 moves, the directional beam of the upward antenna 351 of the UE 35 may always face the relay communication station 150. For example, the directional beam of the upward antenna 351 is made to follow the relay communication station 150 based on the acquisition result of the information of the position change of the communication relay device 15 measured by the GNSS receiver or the like, the transmission / reception result of the pilot signal, and the like. The upward antenna 351 may be mechanically or electrically controlled.

  Further, in the present embodiment, the same frequency band f0 is used in the radio communication of each of the ground cell 10A and the large zone cell 15A, but the wireless communication method in the ground cell 10A and the communication method in the large zone cell 15A may be the same method. However, different methods may be used.

  FIG. 4 is a block diagram showing an example of the main configuration of the UE (mobile station) 35 according to this embodiment. In FIG. 4, the mobile station 35 includes a large zone cell wireless communication unit 353, a ground cell wireless communication unit 354, a control unit 355 that also functions as a switching control unit, a data transmission / reception unit 356, and a service processing unit. And 357.

  The wireless communication unit 353 performs wireless communication with the communication relay device 15 of the large zone cell 15A via the upward antenna 351 in the predetermined frequency band f0 of the service link SL. The wireless communication unit 354 performs wireless communication with the terrestrial cell base station 10 via the downward antenna 352 in the same frequency band f0 as the large zone cell 15A.

  The wireless communication unit 353 and the wireless communication unit 354 include wireless transmission / reception units 3531 and 3541 and modulation / demodulation units 3532 and 3542, respectively. Each of the wireless transmission / reception units 3531 and 3541 includes, for example, a transmission amplifier, a reception amplifier, a frequency converter, and the like. Each of the modulation / demodulation units 3532 and 3542 modulates data to be transmitted by a predetermined coding method and modulation method to generate a transmission signal or demodulates a reception signal to restore the data.

  The modulation / demodulation unit 3542 of the ground-cell wireless communication unit 354 generates communication quality information (for example, RSRP value) of the ground cell 10A based on the received signal received from the ground-cell base station 10 and controls the control unit. Output to 355.

  The control unit 355 controls the wireless communication and the antenna switching by the wireless communication unit 353 and the wireless communication unit 354 by reading and executing a predetermined control program.

  For example, the control unit 355 preferentially performs wireless communication with the terrestrial cell base station 10 via a communication line, and when the communication quality of the wireless communication with the terrestrial cell base station 10 deteriorates or the terrestrial cell When the wireless communication with the base station 10 is disconnected, the communication line with the ground cell base station 10 is released and the communication line with the communication relay device 15 (relay communication station 150) of the large zone cell 15A is established. However, the wireless communication unit 353 and the wireless communication unit 354 may be controlled so that the communication connection destination is switched from the ground cell base station 10 to the communication relay device 15 of the large zone cell 15A.

  In addition, the control unit 355, when the communication quality (for example, RSRP) of the wireless communication with the ground cell base station 10 during the wireless communication by connecting to the large zone cell 15A becomes equal to or higher than a predetermined threshold value, The communication line with the communication relay device 15 of the large zone cell 15A is released, the communication line with the ground cell base station 10 is established, and the communication connection destination is switched from the communication relay device 15 of the large zone cell to the ground cell base station 10. As described above, the wireless communication unit 353 and the wireless communication unit 354 may be controlled.

  The control unit 355 also establishes a communication line between the terrestrial cell base station 10 and each of the communication relay devices 15 of the large zone cells 15A at the same time, and wirelessly communicates with the terrestrial cell base station 10 via the communication line. When communication is preferentially performed and the communication quality of wireless communication with the terrestrial cell base station 10 is deteriorated or the wireless communication with the terrestrial cell base station 10 is disconnected, the communication connection destination is set to the terrestrial cell base station 10 The wireless communication unit 353 and the wireless communication unit 354 may be controlled so as to switch to the communication relay device 15 of the large zone cell 15A.

  Further, the control unit 355, when the communication quality (for example, RSRP) of the wireless communication with the ground cell base station 10 during the wireless communication with the large zone cell 15A becomes equal to or higher than a predetermined threshold value, the communication connection destination. The wireless communication unit 353 and the wireless communication unit 354 may be controlled so as to switch from the communication relay device 15 of the large zone cell 15A to the ground cell base station 10.

  The data transmission / reception unit 256 generates transmission target data based on, for example, a command from the service processing unit 357, and the generated transmission target data is transmitted to the modulation / demodulation unit 3532 and the wireless communication unit 354 of the wireless communication unit 353. It outputs to each of the modulation / demodulation unit 3542 of.

  Further, the data transmission / reception unit 256 receives the reception data received from the large zone cell 15A and the ground cell 10A from the modulation / demodulation unit 3532 of the wireless communication unit 353 and the modulation / demodulation unit 3542 of the wireless communication unit 354, respectively, and the service processing unit 357. Pass to.

  The service processing unit 357, for example, executes various applications that use communication services via wireless communication with the large zone cell 15A or the ground cell 10A, issues an instruction to the data transmission / reception unit 256 to transmit data, or receives data from the data transmission / reception unit 256. Receives received data.

  FIG. 5 is a block diagram showing another example of the main part configuration of the UE (mobile station) 35 according to the present embodiment. The example of FIG. 5 is a configuration example in which the data transmitting / receiving unit 256 is connected to the control unit 355 instead of the modulation / demodulation unit 3532 of the wireless communication unit 353 and the modulation / demodulation unit 3542 of the wireless communication unit 354. In FIG. 5, the same parts as those in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted.

  In FIG. 5, the data transmission / reception unit 256 generates transmission target data based on, for example, a command from the service processing unit 357, and outputs the generated transmission target data to the control unit 355. The control unit 355 outputs the data to be transmitted to the modulation / demodulation unit 3532 of the wireless communication unit 353 or the modulation / demodulation unit 3542 of the wireless communication unit 354 according to the switching of the upward antenna 351 and the downward antenna 352. For example, when the control unit 355 switches to the upward antenna 351 to wirelessly communicate with the large zone cell 15A, the control unit 355 outputs the data to be transmitted to the modulation / demodulation unit 3532 of the wireless communication unit 353 and wirelessly communicates with the ground cell 10A. When the antenna is switched to the downward antenna 352, the data to be transmitted is output to the modulation / demodulation unit 3542 of the wireless communication unit 354.

  Further, in FIG. 5, the control unit 355 controls the reception / reception data received from the large zone cell 15A or the ground cell 10A according to the switching of the upward antenna 351 and the downward antenna 352, and the modulation / demodulation unit 3532 and the wireless communication of the wireless communication unit 353. The data is received from each of the modulation / demodulation units 3542 of the unit 354 and passed to the data transmission / reception unit 256.

FIG. 6 is a flowchart showing an example of cell switching control in the UE (mobile station) 35 according to this embodiment.
In FIG. 6, in order to save power of the communication relay device 15 (relay communication station 150) of the large zone cell 15A and the UE 35 and to cope with resource limitation in the large zone cell 15A, the UE 35 normally gives priority to the ground cell 10A. The downward antenna 352 is selected so as to perform wireless communication, and the downward antenna 352 is connected to the ground cell 10A to establish a communication line and perform wireless communication (S101).

  Next, the UE 35 acquires information on the communication quality (for example, RSRP) of the ground cell 10A, for example, at a predetermined time interval while connecting to the ground cell 10A and performing wireless communication (S102), and the ground cell It is determined whether the communication quality of 10A is deteriorated or the wireless communication with the ground cell 10A is disconnected (S103).

  When the communication quality of the ground cell 10A is deteriorated or the wireless communication with the ground cell 10A is disconnected (YES in S103), the UE 35 switches from the downward antenna 352 to the upward antenna 351 (S104) and via the upward antenna 351. Wireless communication is performed by connecting to the large zone cell 15A to establish a communication line (S105). This allows the UE 35 to smoothly switch from the ground cell 10A to the large zone cell 15A and continuously use various services provided via the mobile communication system, thereby suppressing disconnection of the service. it can.

  Further, since the UE 35 can receive the downlink radio signal from the large zone cell 15A via the upward antenna 351 for the large zone cell 15A, it is possible to suppress the interference of the downlink radio signal from the ground cell. it can. Since the UE 35 can transmit an uplink radio signal to the large zone cell 15A via the upward antenna 351 for the large zone cell 15A, it is possible to suppress interference caused by the uplink radio signal to the ground cell.

  After that, the UE 35 acquires information on the communication quality (for example, RSRP) of the ground cell 10A at, for example, a predetermined time interval while connecting to the large zone cell 15A and performing wireless communication (S106), and the ground cell 10A. It is determined whether or not the communication quality of has been recovered to a predetermined threshold value or more (S107).

  When the communication quality of the ground cell 10A recovers and becomes equal to or higher than a predetermined threshold, the UE 35 switches from the upward antenna 351 to the downward antenna 352 (S108) and connects to the ground cell 10A via the downward antenna 352 to establish a communication line. To establish wireless communication (S109). This allows the UE 35 to smoothly switch from the large zone cell 15A to the ground cell 10A and continuously use various services provided via the mobile communication system, thereby suppressing disconnection of the service. it can.

  Further, since the capacity of the large zone cell 15A is limited, the capacity of the large zone cell 15A can be saved by preferentially connecting to the ground cell 10A for communication during normal times when the communication quality of the ground cell 10A is high. .. Moreover, since it is normally connected to the ground cell 10A, it is possible to save the power of each of the UE 35 and the communication relay device 15 (relay communication station 150) of the large zone cell 15A.

  FIG. 7 is a flowchart showing another example of cell switching control in the UE (mobile station) 35 according to this embodiment. The example of FIG. 7 is a control example in which a communication channel between both the large zone cell 15A and the terrestrial cell 10A and the UE 35 is established in advance. In FIG. 7, the same parts as those in FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted.

  In FIG. 7, the UE 35 is connected to both the large zone cell 15A and the ground cell 10A via the upward antenna 351 and the downward antenna 352 to establish a communication line (S201), and normally only the ground cell 10A and the radio are connected. Communication is performed (S202).

  Next, while performing wireless communication with the ground cell 10A, the UE 35 acquires information on the communication quality (for example, RSRP) of the ground cell 10A at predetermined time intervals (S203), and communicates with the ground cell 10A. It is determined whether the quality is deteriorated or the wireless communication with the ground cell 10A is disconnected (S204).

  When the communication quality of the ground cell 10A is deteriorated or when the wireless communication with the ground cell 10A is disconnected (YES in S204), the UE 35 switches from the downward antenna 352 to the upward antenna 351 and the large zone cell 15A via the upward antenna 351. Wireless communication is performed (S205). This allows the UE 35 to smoothly switch from the ground cell 10A to the large zone cell 15A and continuously use various services provided via the mobile communication system, thereby suppressing disconnection of the service. it can.

  Particularly, in this example, by establishing a communication line with the large zone cell 15A in advance, a service with high redundancy can be more smoothly and surely maintained when communication with the ground cell 10A is disconnected.

  Further, since the UE 35 can receive the downlink radio signal from the large zone cell 15A via the upward antenna 351 for the large zone cell 15A, it is possible to suppress the interference of the downlink radio signal from the ground cell. it can. Since the UE 35 can transmit an uplink radio signal to the large zone cell 15A via the upward antenna 351 for the large zone cell 15A, it is possible to suppress interference caused by the uplink radio signal to the ground cell.

  After that, the UE 35 acquires information on the communication quality (for example, RSRP) of the ground cell 10A at, for example, a predetermined time interval while performing wireless communication by connecting to the large zone cell 15A (S206), and the ground cell 10A. It is determined whether or not the communication quality of has recovered to a predetermined threshold value or more (S207).

  When the communication quality of the ground cell 10A recovers and becomes equal to or higher than a predetermined threshold value, the UE 35 switches from the upward antenna 351 to the downward antenna 352 and performs wireless communication with the ground cell 10A via the downward antenna 352 (S208). This allows the UE 35 to smoothly switch from the large zone cell 15A to the ground cell 10A and continuously use various services provided via the mobile communication system, thereby suppressing disconnection of the service. it can.

  Particularly, in this example, by establishing a communication line with the ground cell 10A in advance, a service with high redundancy can be more smoothly and surely maintained when returning to communication with the ground cell 10A.

  Moreover, since the capacity of the large zone cell 15A is limited, the capacity of the large zone cell 15A can be saved by preferentially communicating with the ground cell 10A during normal times when the communication quality of the ground cell 10A is high. In addition, since the communication is normally performed with the ground cell 10A, it is possible to save the power of each of the UE 35 and the communication relay device 15 (relay communication station 150) of the large zone cell 15A.

  FIG. 8 is a flowchart showing still another example of cell switching control in the UE (mobile station) 35 according to this embodiment. The example of FIG. 8 is an example of control for switching cells based on the position information of the UE 35 instead of the communication quality at the time of cell connection. In this example, the UE 35 includes a position detection unit that detects the current position of the UE itself by measurement using GNSS such as GPS.

  In FIG. 8, the UE 35 selects the downward antenna 352 so as to preferentially select the terrestrial cell 10A and perform radio communication at a normal time, and connects with the terrestrial cell 10A through the downward antenna 352 to establish a communication line. Wireless communication is performed (S301).

  Next, the UE 35 detects the current position of the UE itself at, for example, a predetermined time interval while connecting to the ground cell 10A and performing wireless communication (S302), and based on the position information, the UE 35. Is located inside or outside the three-dimensional area of the ground cell capable of communicating with the ground cell base station 10 (S303).

  When the UE 35 moves out of the three-dimensional area of the terrestrial cell that can communicate with the terrestrial cell base station 10, the UE 35 switches from the downward antenna 352 to the upward antenna 351 (S304) and connects to the large zone cell 15A via the upward antenna 351. Then, a communication line is established and wireless communication is performed (S305). This allows the UE 35 to smoothly switch from the ground cell 10A to the large zone cell 15A and continuously use various services provided via the mobile communication system, thereby suppressing disconnection of the service. it can.

  Further, since the UE 35 can receive the downlink radio signal from the large zone cell 15A via the upward antenna 351 for the large zone cell 15A, it is possible to suppress the interference of the downlink radio signal from the ground cell. it can. Since the UE 35 can transmit an uplink radio signal to the large zone cell 15A via the upward antenna 351 for the large zone cell 15A, it is possible to suppress interference caused by the uplink radio signal to the ground cell.

  After that, when the UE 35 is connected to the large zone cell 15A and is performing wireless communication, the UE 35 detects the current position of the UE itself at, for example, a predetermined time interval (S306), and the UE 35 detects the current position based on the position information. It is determined whether the vehicle is located inside or outside the three-dimensional area of the ground cell that can communicate with the ground cell base station 10 (S307).

  When the UE 35 moves into the three-dimensional area of the terrestrial cell that can communicate with the terrestrial cell base station 10, the UE 35 switches from the upward antenna 351 to the downward antenna 352 (S308) and connects with the terrestrial cell 10A via the downward antenna 352. Then, a communication line is established and wireless communication is performed (S309). This allows the UE 35 to smoothly switch from the large zone cell 15A to the ground cell 10A and continuously use various services provided via the mobile communication system, thereby suppressing disconnection of the service. it can.

  Further, since the capacity of the large zone cell 15A is limited, the capacity of the large zone cell 15A can be saved by preferentially connecting to the ground cell 10A for communication during normal times when the communication quality of the ground cell 10A is high. .. Moreover, since it is normally connected to the ground cell 10A, it is possible to save the power of each of the UE 35 and the communication relay device 15 (relay communication station 150) of the large zone cell 15A.

  FIG. 9 is a flowchart showing still another example of cell switching control in the UE (mobile station) 35 according to this embodiment. The example of FIG. 9 is a control example in which communication lines between both the large zone cell 15A and the terrestrial cell 10A and the UE 35 are established in advance, and the cells are switched based on the position information of the UE 35 instead of the communication quality at the time of cell connection. .. In this example, the UE 35 includes a position detection unit that detects the current position of the UE itself by measurement using GNSS such as GPS.

  In FIG. 9, the UE 35 is connected to both the large zone cell 15A and the ground cell 10A via the upward antenna 351 and the downward antenna 352 to establish a communication line (S401), and normally, only the ground cell 10A and the radio are connected. Communication is performed (S402).

  Next, while performing radio communication with the ground cell 10A, the UE 35 detects the current position of the UE itself at predetermined time intervals (S403), and based on the position information, the UE 35 detects the ground cell It is determined whether it is located inside or outside the three-dimensional area of the ground cell that can communicate with the base station 10 (S404).

  When the UE 35 moves outside the three-dimensional area of the terrestrial cell that can communicate with the terrestrial cell base station 10, the UE 35 switches from the downward antenna 352 to the upward antenna 351 and performs large zone cell 15A wireless communication via the upward antenna 351 ( S405). This allows the UE 35 to smoothly switch from the ground cell 10A to the large zone cell 15A and continuously use various services provided via the mobile communication system, thereby suppressing disconnection of the service. it can.

  Particularly, in this example, by establishing a communication line with the large zone cell 15A in advance, a service with high redundancy can be more smoothly and surely maintained when communication with the ground cell 10A is disconnected.

  Further, since the UE 35 can receive the downlink radio signal from the large zone cell 15A via the upward antenna 351 for the large zone cell 15A, it is possible to suppress the interference of the downlink radio signal from the ground cell. it can. Since the UE 35 can transmit an uplink radio signal to the large zone cell 15A via the upward antenna 351 for the large zone cell 15A, it is possible to suppress interference caused by the uplink radio signal to the ground cell.

  After that, when the UE 35 is connected to the large zone cell 15A and is performing wireless communication, the UE 35 detects the current position of the UE itself, for example, at a predetermined time interval (S406), and the UE 35 detects the current position based on the position information. It is determined whether the vehicle is located inside or outside the three-dimensional area of the ground cell that can communicate with the ground cell base station 10 (S407).

  When the UE 35 moves into the three-dimensional area of the ground cell that can communicate with the ground cell base station 10, the UE 35 switches from the upward antenna 351 to the downward antenna 352 and performs wireless communication with the ground cell 10A via the downward antenna 352. (S408). This allows the UE 35 to smoothly switch from the large zone cell 15A to the ground cell 10A and continuously use various services provided via the mobile communication system, thereby suppressing disconnection of the service. it can.

  Particularly, in this example, by establishing a communication line with the ground cell 10A in advance, a service with high redundancy can be more smoothly and surely maintained when returning to communication with the ground cell 10A.

  Moreover, since the capacity of the large zone cell 15A is limited, the capacity of the large zone cell 15A can be saved by preferentially communicating with the ground cell 10A during normal times when the communication quality of the ground cell 10A is high. In addition, since the communication is normally performed with the ground cell 10A, it is possible to save the power of each of the UE 35 and the communication relay device 15 (relay communication station 150) of the large zone cell 15A.

  Further, the processing steps and the mobile communication system, the large-zone cell relay communication station 150, the large-zone cell base station 70, the terrestrial cell base station 10, and the user terminal devices (mobile stations) 30, 31, 35 described in the present specification. Elements can be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof.

  As for hardware implementation, means such as a processing unit used to implement the above steps and components in a substance (for example, various wireless communication devices, Node Bs, terminals, hard disk drive devices, or optical disk drive devices) One or more application specific ICs (ASICs), digital signal processors (DSPs), digital signal processors (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors , A controller, a microcontroller, a microprocessor, an electronic device, other electronic units designed to perform the functions described herein, a computer, or a combination thereof.

  Also, for firmware and / or software implementations, means such as processing units used to implement the components described above may be programs (eg, procedures, functions, modules, instructions) that perform the functions described herein. , Etc.) may be implemented. In general, any computer / processor readable medium embodying firmware and / or software code, means, such as a processing unit, used to implement the steps and components described herein. May be used to implement. For example, firmware and / or software code may be stored in memory and executed by a computer or processor, eg, at the controller. The memory may be mounted inside the computer or the processor, or may be mounted outside the processor. The firmware and / or software code may be, for example, random access memory (RAM), read only memory (ROM), non-volatile random access memory (NVRAM), programmable read only memory (PROM), electrically erasable PROM (EEPROM). ), A FLASH memory, a floppy disk, a compact disk (CD), a digital versatile disk (DVD), a magnetic or optical data storage device, and the like, even when stored on a computer or processor readable medium. Good. The code may be executed by one or more computers or processors and may cause the computers or processors to perform the functional aspects described herein.

  Further, the medium may be a non-transitory recording medium. In addition, the code of the program may be readable and executable by a computer, a processor, or another device or machine, and its format is not limited to a particular format. For example, the code of the program may be any of source code, object code, and binary code, or may be a mixture of two or more of these codes.

  Also, 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 this 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 this disclosure. Therefore, the present disclosure should not be limited to the examples and designs described herein, but should be admitted to the broadest extent consistent with the principles and novel features disclosed herein.

10 ground cell base station 10A ground cell 15 communication relay device (aircraft)
15A large zone cell 30 ground-based mobile station (user terminal device, UE) connected to a ground cell
31 Terrestrial mobile stations (user terminals, UE) connected to large zone cells
35 Mobile station in the sky (user terminal device, UE)
150 Large Zone Cell Relay Communication Station 351 Upward Antenna 352 Downward Antenna 353, 354 Radio Communication Section 355 Control Section 356 Data Transmission / Reception Section 357 Service Processing Device 3531, 3541 Transceiver 3532, 3542 Modulation / Demodulation Section

Claims (18)

A mobile station of a mobile communication system,
Used in a state of being located between a communication relay device forming a large zone cell and a low altitude base station located at a lower altitude than the communication relay device,
A plurality of antennas used in the same frequency band, the first antenna having a directional beam above the horizontal direction and the second antenna having a directional beam below the horizontal direction;
A wireless communication unit that wirelessly communicates with the communication relay device of the large zone cell via the first antenna in the same frequency band and wirelessly communicates with the low altitude base station via the second antenna;
A mobile station comprising: In the mobile station according to claim 1,
Select preferentially wireless communication via a communication line with the low altitude base station,
When the communication quality of wireless communication with the low-altitude base station is deteriorated or when the wireless communication with the low-altitude base station is disconnected, a communication line with the communication relay device of the large zone cell is provided. A mobile station comprising a switching control unit that is established and switches a communication connection destination from the low-altitude base station to the communication relay device of the large zone cell. In the mobile station according to claim 1 or 2,
When the wireless communication via the communication line with the communication relay device of the large zone cell is selected and the communication quality of the wireless communication with the low altitude base station becomes equal to or higher than a predetermined threshold value. A mobile station, characterized by establishing a communication line with the low-altitude base station and switching a communication connection destination from the communication relay device of the large zone cell to the low-altitude base station. In the mobile station according to claim 1,
A communication line is established between each of the low altitude base station and the communication relay device of the large zone cell,
Select preferentially wireless communication via a communication line with the low altitude base station,
When the communication quality of wireless communication with the low-altitude base station deteriorates or when the wireless communication with the low-altitude base station is disconnected, the communication connection destination from the low-altitude base station to the large zone cell A mobile station comprising a switching control unit for switching to the communication relay device. In the mobile station according to claim 1 or 4,
When the wireless communication via the communication line with the communication relay device of the large zone cell is selected and the communication quality of the wireless communication with the low altitude base station becomes equal to or higher than a predetermined threshold value. The mobile station is characterized in that the communication connection destination is switched from the communication relay device of the large zone cell to the low altitude base station and a communication line is maintained between the communication relay device of the large zone cell. In the mobile station according to claim 1,
Select preferentially wireless communication via a communication line with the low altitude base station,
The position information of the mobile station is used to determine whether the mobile station is located inside or outside a three-dimensional area in which the mobile station can communicate with the low-altitude base station, and the mobile station is located outside the three-dimensional area. When the mobile station moves to, the communication line is established with the communication relay device of the large zone cell, and a switching control unit for switching the communication connection destination from the base station of the low altitude to the communication relay device of the large zone cell is provided. And mobile stations. In the mobile station according to claim 1 or 6,
When the wireless communication via the communication line with the communication relay device of the large zone cell is selected, the mobile station can communicate with the low altitude base station by using the position information of the mobile station. Determine whether it is located inside or outside the three-dimensional area,
When the mobile station moves into the three-dimensional area, establish a communication line with the low-altitude base station, and switch the communication connection destination from the communication relay device of the large zone cell to the low-altitude base station. Characteristic mobile station. In the mobile station according to claim 1,
A communication line is established between each of the low altitude base station and the communication relay device of the large zone cell,
Priority is given to wireless communication via a communication line with the low altitude base station,
Using the position information of the mobile station, to determine whether the mobile station is located in or outside the three-dimensional area capable of communicating with the low altitude base station,
A mobile station, comprising: a switching control unit that switches a communication connection destination from the low-altitude base station to the communication relay device of the large zone cell when the mobile station moves out of the three-dimensional area. In the mobile station according to claim 1 or 8,
When selecting wireless communication via a communication line with the communication relay device of the large zone cell, using the position information of the mobile station, the mobile station is a three-dimensional area of the low altitude base station. Determine whether it is inside or outside,
When the mobile station moves into the three-dimensional area, the communication connection destination is switched from the communication relay device of the large zone cell to the low altitude base station, and a communication line is maintained between the mobile station and the communication relay device of the large zone cell. A mobile station characterized by: The mobile station according to any one of claims 6 to 9,
A mobile station comprising a position detection unit that detects the current position of the mobile station itself using a GNSS (Global Navigation Satellite System). The mobile station according to any one of claims 1 to 10,
A mobile station, which is provided in an air vehicle that can move in a space between the low-altitude base station and the communication relay device of the large zone cell. In the mobile station according to claim 11,
The aircraft is located in the space between the low-altitude base station and the communication relay device of the large zone cell, by self-sustaining control or external control, or by the operation of an operator on the aircraft. A mobile station characterized by being controlled. The mobile station according to claim 11 or 12,
The mobile station, wherein the flying body is a drone, an airship, a balloon, an aircraft, a helicopter, or HAPS. The mobile station according to any one of claims 1 to 13,
The low-altitude base station is a base station that forms a macro cell or a small cell on the ground or at sea.
The mobile station, wherein the communication relay device of the large zone cell is a large zone cell base station forming a large zone cell having a cell size on the ground or at sea larger than that of the macro cell and the small cell.   An aircraft comprising the mobile station according to claim 1. The air vehicle according to claim 15,
In order to be located in the space between the low altitude base station and the communication relay device of the large zone cell, it is controlled by self-sustaining control or control from the outside, or by the control of the pilot on board the aircraft. Characterized flying body. A mobile communication system,
A mobile station according to any one of claims 1 to 13,
A communication relay device forming a large zone cell;
A low-altitude base station located at a lower altitude than the communication relay device, and a mobile communication system. The mobile communication system according to claim 17,
The low-altitude base station is a base station that forms a macro cell or a small cell on the ground or at sea.
The mobile communication system, wherein the communication relay device of the large zone cell forms a large zone cell having a cell size on the ground or at sea larger than that of the macro cell and the small cell.

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