Wireless relay system, wireless relay method, relay station master unit, management device, and program

Abstract

To provide a wireless relay system capable of improving the quality of downlink signals of a feeder link corresponding to remaining cells other than the suspended cells when the operation of some of a plurality of cells formed via an overhead relay station slave unit is suspended, without increasing the total feeder link transmission power of the relay station master unit. [Solution] In a non-regenerative relay wireless relay system that relays wireless communications between a base station and terminal devices located in multiple cells via a feeder link between a relay station parent unit installed in a gateway device on land or sea and a relay station child unit installed in an aircraft or floating body in the sky, the relay station parent unit has a power distribution unit that, when operation of some of the multiple cells is suspended, distributes the power of a downlink signal corresponding to a suspended cell to the power of a downlink signal corresponding to the remaining cells other than the suspended cell.

Description

[Technical field]

[0001] The present disclosure relates to non-regenerative wireless relaying. [Background technology]

[0002] Conventionally, a non-regenerative relay type wireless relay system is known that includes a relay station master unit provided in a gateway device on land or sea and a relay station slave unit provided in an aircraft or floating body in the sky, and relays wireless communication between a base station and terminal devices of multiple cells via a feeder link between the relay station master unit and the relay station slave unit (see, for example, Patent Document 1). The relay station slave unit performs wireless communication of the feeder link with the relay station master unit, and wireless communication of a service link with terminal devices of multiple cells formed toward the ground. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-167539 A Summary of the Invention

[0004] A wireless relay system according to an aspect of the present disclosure is a non-regenerative relay type wireless relay system that includes a relay station master unit provided in a ground or sea gateway device and a relay station slave unit provided in an aircraft or floating body in the sky, and relays wireless communications between a base station and terminal devices located in a plurality of cells via a feeder link between the relay station master unit and the relay station slave unit. The relay station master unit has a power distribution unit that distributes, when operation of some of the plurality of cells is suspended, the power of a downlink signal corresponding to the suspended cell to the power of a downlink signal corresponding to the remaining cells other than the suspended cell.

[0005] In the wireless relay system, the relay station parent device has a judgment unit that judges whether to suspend operation of some of the multiple cells, and the power distribution unit of the relay station parent device may distribute, based on a result of the judgment by the judgment unit, the power of a downlink signal corresponding to a suspended cell to the power of a downlink signal corresponding to the remaining cells other than the suspended cell.

[0006] In the wireless relay system, the relay station parent device has a monitoring unit that monitors a plurality of synchronization signals transmitted from the base station at regular time intervals for the plurality of cells, and the determination unit of the relay station parent device may determine to stop operation of some of the plurality of cells based on the power of the plurality of synchronization signals.

[0007] In the wireless relay system, the monitoring unit of the relay station master may estimate power of the plurality of synchronization signals based on a correlation process between a received signal received from the base station and a replica of the synchronization signal.

[0008] In the wireless relay system, the relay station parent device has a monitoring unit that monitors multiple synchronization signals transmitted from the base station at regular time intervals for the multiple cells, the monitoring unit of the relay station parent device calculates multiple correlation coefficients by correlation processing between a received signal received from the base station and a replica of the synchronization signal, and the judgment unit of the relay station parent device may judge to stop operation of some of the multiple cells based on values ​​of the multiple correlation coefficients.

[0009] In the wireless relay system, the judgment unit of the relay station parent device may determine that operation of the cell has been stopped if the power of the synchronization signal corresponding to the cell or the value of the correlation coefficient continues to be below a predetermined threshold value during a predetermined judgment period, and may determine that the cell is in operation if the power of the synchronization signal corresponding to the cell or the value of the correlation coefficient is greater than the threshold value at least once during the predetermined judgment period.

[0010] The wireless relay system may further include a management device. The management device may include an information acquisition unit that acquires sky position information of the flying object or the floating object on which the relay station slave device is provided, a determination unit that determines whether to suspend operation of a part of the plurality of cells based on the sky position information of the flying object or the floating object, and an information transmission unit that transmits a result of the determination by the determination unit to the relay station master device. The power distribution unit of the relay station master device may receive a result of the determination by the determination unit from the management device, and distribute power of a downlink signal corresponding to a suspended cell to power of a downlink signal corresponding to a remaining cell other than the suspended cell based on the result of the determination.

[0011] In the wireless relay system, the aerial position information may include information on the current position and planned movement route of the flying object or the floating object in the air.

[0012] In the wireless relay system, the information acquisition unit of the management device may acquire the aerial position information via a satellite line, or via a feeder link line between the relay station parent unit and the relay station child unit and the relay station parent unit.

[0013] In the wireless relay system, the decision unit of the relay station parent device and the power distribution unit of the relay station parent device may distribute the power of a downlink signal corresponding to a suspended cell to the power of a downlink signal corresponding to the remaining cells other than the suspended cell based on the result of the judgment received from the management device and the result of the judgment of the judgment unit of the relay station parent device.

[0014] In the wireless relay system, when it is determined that some of the multiple cells are out of operation, the power distribution unit of the relay station parent device may evenly distribute surplus power generated by the suspension of operation of the cell to the power of downlink signals corresponding to the remaining cells other than the suspended cell.

[0015] A relay station master unit according to another aspect of the present disclosure is a relay station master unit provided in a gateway device on land or sea. This relay station master unit is combined with a relay station slave unit provided in an aircraft or floating body in the sky to form a wireless relay system using a non-regenerative relay method. The relay station master unit has a power distribution unit that distributes the power of a downlink signal corresponding to a cell that has been stopped in operation to the power of a downlink signal corresponding to the remaining cells other than the cell that has been stopped in operation when the operation of a part of the cells formed via the relay station slave unit is stopped.

[0016] A management device according to yet another aspect of the present disclosure is a management device in a wireless relay system of a non-regenerative relay method, which includes a relay station master provided in a ground or sea gateway device and a relay station slave provided in an aircraft or floating body located in the sky. This management device includes an information acquisition unit that acquires sky position information of the aircraft or floating body on which the relay station slave is provided, a determination unit that determines whether to suspend operation of a part of a plurality of cells formed via the relay station slave based on the sky position information of the aircraft or floating body, and an information transmission unit that transmits the result of the determination by the determination unit to the relay station master.

[0017] A method according to still another aspect of the present disclosure is a wireless relay method of a non-regenerative relay system that relays wireless communication between a base station and terminal devices located in a plurality of cells via a relay station master unit provided in a ground or sea gateway device and a relay station slave unit provided in an aircraft or floating body located in the sky. This wireless relay method includes distributing, when operation of some of the plurality of cells is suspended, the power of a downlink signal corresponding to the suspended cell to the power of a downlink signal corresponding to the remaining cells other than the suspended cell.

[0018] A program according to still another aspect of the present disclosure is a program executed by a computer or processor provided in a relay station master in a non-regenerative relay type wireless relay system including a relay station master provided in a ground or sea gateway device and a relay station slave provided in an aircraft or floating body located in the sky, the program including a program code for distributing, when operation of some of a plurality of cells formed via the relay station slave is suspended, the power of a downlink signal corresponding to the suspended cell to the power of a downlink signal corresponding to the remaining cell other than the suspended cell.

[0019] A program according to yet another aspect of the present disclosure is a program executed by a computer or processor provided in a management device in a wireless relay system of a non-regenerative relay method, which includes a relay station master provided in a ground or sea gateway device and a relay station slave provided in an aircraft or float in the sky. This program includes: program code for acquiring sky position information of the aircraft or float in which the relay station slave is provided; program code for determining, based on the sky position information of the aircraft or float, whether or not a part of a plurality of cells formed via the relay station slave is to be suspended; and program code for transmitting the result of the determination to the relay station master.

[0020] The program of the present disclosure may also include a trained model used for machine learning. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a diagram illustrating an example of an overall configuration of a wireless relay system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram illustrating an example of a problem that occurs when relaying a downlink signal in a wireless relay system. [Diagram 3] FIG. 3 is a diagram illustrating another example of a problem that occurs when relaying a downlink signal in a wireless relay system. [Figure 4]FIG. 4 is a diagram illustrating an example of a configuration of main parts of a relay station master unit and a relay station slave unit of the wireless relay system according to the embodiment. [Diagram 5] FIG. 5 is a diagram illustrating an example of a synchronization signal in a radio frame of a transmission signal transmitted from a base station. [Figure 6] FIG. 6 is a diagram illustrating an example of a configuration of a main part of a wireless relay system including a management device according to an embodiment. [Figure 7] FIG. 7 is a diagram showing another example of a configuration of a main part of a wireless relay system including a management device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Note that each drawing merely shows a schematic diagram of the shape, size, positional relationship, corresponding relationship, configuration, processing, steps, procedures, etc., to the extent that the contents of the present disclosure can be understood, and therefore the present disclosure is not limited to only the shape, size, positional relationship, corresponding relationship, configuration, processing, steps, and procedures exemplified in each drawing. Also, the numerical values ​​exemplified in the present disclosure are merely preferred examples, and therefore the present disclosure is not limited to the numerical values ​​exemplified.

[0023] A system according to an embodiment of the present disclosure is a wireless relay system that, when some of a plurality of cells formed via an overhead relay station slave unit are suspended, distributes transmission power to the remaining cells on the feeder link to improve the quality of downlink signals of the feeder link corresponding to the remaining cells other than the suspended cells. The wireless relay system according to the present embodiment is suitable for realizing a three-dimensional network in mobile communications conforming to next-generation standards such as mobile communications conforming to the LTE (Long Term Evolution)-Advanced standard and the fifth generation (hereinafter also referred to as "5GNR") that supports simultaneous connection to a large number of terminal devices and low latency.

[0024] 1 is a diagram showing an example of the overall configuration of a wireless relay system 10 according to an embodiment. The wireless relay system 10 is a non-regenerative relay type wireless relay system including a relay station master 21 provided in a ground or sea gateway device 20 and a relay station slave 31 provided in an aircraft or floating body in the sky, and relaying wireless communication between a base station 40 and a terminal device 50 located in a plurality of cells 300C(1) to 300C(3) via a feeder link FL between the relay station master 21 and the relay station slave 31.

[0025] In the wireless relay system of this embodiment, the flying object or floating object on which the relay station slave unit 31 is mounted is, for example, a high altitude platform station ("high altitude pseudo satellite" or "stratospheric platform") (hereinafter also referred to as "HAPS" or "airborne platform (HAPS)") 30 as an airborne radio relay device. The HAPS 30 is located in an airspace at a predetermined altitude and forms a three-dimensional cell (also referred to as "HAPS cell") as a wide-area cell consisting of a plurality of cells 300C(1) to 300C(3). The HAPS 30 is an flying object or floating object (for example, a solar plane, an airship, a drone, or a balloon) that is controlled by autonomous control or external control to float or fly and position in an airspace (floating airspace) at a predetermined altitude from the ground or sea surface. The HAPS 30 that can function as an airborne communication relay device may be an artificial satellite such as a low Earth orbit (LEO) satellite or a geostationary orbit (GEO) satellite, on which a relay communication station is mounted. Furthermore, the wireless relay system of the present embodiment may include one or more terminal devices 50 with which the HAPS 30 communicates, and may also include a gateway device 20 (also called a “gateway station” or a “feeder station”).

[0026] The airspace in which HAPS30 is located is, for example, the stratospheric airspace at an altitude of 11 km or more and 50 km or less above the ground (or above water such as the sea or lake). This airspace may be an airspace with relatively stable weather conditions at an altitude of 15 km or more and 25 km or less, and in particular may be an airspace with an altitude of approximately 20 km.

[0027] HAPS30 flies at a lower altitude than general artificial satellites and higher than terrestrial and marine base stations, so it can ensure high visibility while having smaller propagation loss than satellite communications. This feature makes it possible to provide communication services from HAPS30 to terminal equipment (mobile stations) 50, which are user equipment such as terrestrial or marine cellular mobile terminals. Providing communication services from HAPS30 has the advantage of being able to provide stable communication services at low cost, since a small number of HAPS30 can cover a wide area that was previously covered by many terrestrial or marine base stations at once.

[0028] The relay station slave unit 31 of the HAPS 30 forms a plurality of cells (also called "HAPS cells") 300C(1)-300C(3) capable of wireless communication with the user terminal device (hereinafter called "UE" (user device)) 50, by forming a plurality of beams toward the ground (or sea surface) using a service link antenna (hereinafter called "SL antenna") for wireless communication with the user terminal device (hereinafter called "UE" (user device)) 50. The radius of the service area (also called "HAPS service area") consisting of the footprints of these cells on the ground (or sea) is, for example, several tens of kilometers to 100 kilometers.

[0029] In this embodiment, the relay station slave device 31 of the HAPS 30 forms three cells 300C(1) to 300C(3), but the number of cells formed by the relay station slave device 31 may be two, four, five, six, or seven cells, or may be eight or more cells.

[0030] UE50 may be a communication terminal module incorporated in a drone, which is an aircraft such as a small remotely controlled helicopter, or it may be a user device used by a user in an aircraft such as an airplane.

[0031] The relay station slave 31 of the HAPS 30 is, for example, a repeater slave that wirelessly communicates with a relay station master (repeat master) 21 mounted on a gateway device (also called a "gateway station" or "feeder station", hereinafter referred to as a "GW station") 20 connected to a terrestrial (or marine) base station 40. The relay station slave 31 is connected to a core network of a mobile communication network via the GW station 20, the base station 40, and a network device 65, which are installed on land or sea and can wirelessly communicate with each other by a feeder link antenna (hereinafter referred to as an "FL antenna").

[0032] Communication over the feeder link FL between the relay station slave 31 of the HAPS 20 and the relay station master 21 of the GW station 20 may be carried out by wireless communication using radio waves such as microwaves, millimeter waves, and submillimeter waves, or by optical communication using laser light, for example.

[0033] The GW station 20 may control its own antenna (hereinafter referred to as "GW antenna") 22 to track the HAPS 30 moving in the air. By having the GW antenna 22 track the HAPS 30, it is possible to suppress degradation of communication quality of the feeder link FL due to movement of the HAPS 30 even when a GW antenna 22 having high directivity such as a parabolic antenna is used.

[0034] The base station 40 includes a plurality of base station devices (e.g., eNodeB, gNodeB) 41(1)-41(3) corresponding to a plurality of 300C(1)-300C(3). In the case of an LTE eNodeB, for example, each of the base station devices 41(1)-41(3) is configured with a remote radio device (RRH (Remote Radio Head), also called an RRU (Remote Radio Unit)) and a baseband processing device (BBU (Base Band Unit)). The RRH and BBU may be connected to each other by optical fiber lines and placed separately from each other. Also, a plurality of BBUs may be aggregated and placed in one place.

[0035] Each of the RRHs of the multiple base station devices 41(1) to 41(3) includes, for example, an orthogonal modulation / demodulation unit, a transmission unit, a reception unit, a power amplifier (PA (Power Amplifier)), and a low noise receiver (LNA (Low Noise Amplifier)), and is connected to the GW station 20. The orthogonal modulation / demodulation unit performs orthogonal modulation / demodulation on the OFDM signal processed by the BBU, and converts it into an analog signal (RF signal). The transmission unit converts the frequency of the RF signal generated by the orthogonal modulation / demodulation unit into a frequency to be transmitted as a radio wave. The reception unit converts the frequency of the high-frequency signal of the received radio wave into a frequency to be processed by the orthogonal modulation / demodulation unit. The power amplifier (PA) power-amplifies the RF signal generated by the transmission unit. The low noise receiver (LNA) amplifies the received weak radio wave and passes it to the reception unit.

[0036] Each of the BBUs of the multiple base station devices 41(1) to 41(3) includes, for example, a base station control unit, a transmission line interface unit, a timing control unit, and a baseband unit, and is connected to a core network of a mobile communication network via a predetermined interface (for example, an S1 interface). The base station control unit controls the entire base station and performs call control protocol and control monitoring. The transmission line interface unit is connected to a packet transmission line such as Ethernet (registered trademark) between the core network and the like, and processes a predetermined protocol to transmit and receive IP packets. The timing control unit generates various clocks used within the base station based on a reference clock extracted from a signal received via the packet transmission line or a GNSS (Global Navigation Satellite System) received signal from an artificial satellite. The baseband unit converts (modulates and demodulates) IP packets and OFDM signals (baseband signals), which are wireless signals, transmitted and received via the transmission line interface unit.

[0037] Each HAPS 30 may autonomously control the levitation movement (flight) of the HAPS itself and the processing in the relay station slave unit 31 by executing a control program with a control unit configured with an internally incorporated computer or the like. For example, each HAPS 20 may acquire current position information of the HAPS itself (e.g., GPS position information), pre-stored position control information (e.g., flight schedule information), position information of other HAPS 30 located in the vicinity, and the like, and autonomously control the levitation movement (flight) and the processing in the relay station slave unit 31 based on that information.

[0038] Furthermore, the levitation (flight) of each HAPS 30 and the processing in the relay station slave unit 31 may be controlled by a management device (also called a "remote control device" or "central control server") provided in a communication center or the like connected to the core network of the mobile communication network. The management device may be configured, for example, as a computer device such as a PC, a server, or the like. In this case, the HAPS 30 includes a control communication unit (e.g., a mobile communication module) for receiving control information from the management device and transmitting various information such as monitoring information to a predetermined destination such as the management device. The control communication unit may be assigned terminal identification information (e.g., an IP address, a telephone number, etc.) so as to be able to communicate with the management device. The MAC address of the communication interface may be used to identify the control communication unit of the HAPS 30.

[0039] Transmission and reception of control information and monitoring information between HAPS 30 and the management device can be performed, for example, via an LTE communication line passing through a core network of a mobile communication network, a base station 40, and a GW station 20. In addition, transmission and reception of control information and monitoring information may be performed using a mobile communication satellite line via an artificial satellite, or may be performed using a satellite line via the Internet and an artificial satellite.

[0040] The monitoring information transmitted from the HAPS 30 may include at least one of the following: information on the floating movement (flight) of the HAPS itself or surrounding HAPS, information on processing at the relay station slave unit 31, monitoring information including a reception level measuring the reception power of the feeder link between the HAPS 30 and the GW station 20, and information on the status of the HAPS 30 and information on observation data acquired by various sensors. The monitoring information may also include at least one of the following: current position and attitude information of the HAPS 40, flight route information (flight schedule information, flight route history information), airspeed, ground speed and propulsion direction, wind speed and direction of air currents around the HAPS 20, and air pressure and temperature around the HAPS 30. The control information may include flight information such as target flight route information of the HAPS 30.

[0041] The HAPS 30 and the management device may acquire weather forecast information for an area including the wireless propagation path of the feeder link, maintenance schedule information for the GW station 20 or the base station 40, reception level monitor information of the feeder link with the GW station 20 measured by the HAPS 30, flight route information for the HAPS 30, and current location information and attitude information for the HAPS 30. These pieces of information may be acquired, for example, from a server in a core network (mobile communication network) that manages each piece of information or a server on the Internet. In addition, the management device may acquire the maintenance schedule information for the GW station 20 or the base station 40 from the GW station 20 or the base station 40 via a core network of the mobile communication network by a predetermined interface (for example, an S1 interface of LTE), or may acquire it from a server that manages the GW station 20 or the base station 40.

[0042] The duplexing method of the uplink and downlink of the wireless communication of the service link SL between the relay station slave 31 and the terminal device 50 is not limited to a specific method, and may be, for example, a time division duplex (TDD) method or a frequency division duplex (FDD) method. The access method of the wireless communication of the service link SL between the relay station slave 31 and the terminal device 50 is not limited to a specific method, and may be, for example, a frequency division multiple access (FDMA) method, a time division multiple access (TDMA) method, a code division multiple access (CDMA) method, or an orthogonal frequency division multiple access (OFDMA) method. The wireless communication may use a multi-input and multi-output (MIMO) technology that has functions such as diversity coding, transmission beamforming, and spatial division multiplexing (SDM) and can increase the transmission capacity per unit frequency by simultaneously using multiple antennas for both transmission and reception. Furthermore, the MIMO technology may be a single-user MIMO (SU-MIMO) technology in which one base station transmits multiple signals to one terminal device at the same time and frequency, or a multi-user MIMO (MU-MIMO) technology in which one base station transmits signals to multiple different terminal devices at the same time and frequency.

[0043] In the following embodiment, the HAPS 30 having the relay station slave unit 31 that wirelessly communicates with the terminal device 50 is illustrated and described as a solar plane type HAPS, but the HAPS 30 may be an unmanned airship type HAPS. The following embodiment can also be applied to a floating communication relay device made of an aircraft or floating body other than a HAPS.

[0044] Moreover, the link between the HAPS 30 and the base station 40 via the GW station 20 is called a "feeder link" FL, and the link between the HAPS 30 and the terminal device 50 is called a "service link" SL. In particular, the section between the HAPS 30 and the GW station 20 is called a "wireless section of the feeder link." Moreover, the downlink of communication from the GW station 20 to the terminal device 50 via the HAPS 30 is also called a "forward link," and the uplink of communication from the terminal device 50 to the GW station 20 via the HAPS 30 is also called a "reverse link."

[0045] In the wireless relay system 10 having the above configuration, multiple downlink signals S1, S2, S3 of the same frequency of a service link corresponding to multiple cells 300(1), 300(2), 300(3) are output from multiple base station devices 41(1), 41(2), 41(3) of the base station 40 and received by the relay station parent device 21 of the GW station 20.

[0046] The relay station parent device 21 performs parallel / serial conversion processing on the multiple downlink signals S1, S2, S3 received from the base station 40, converting them into multiple downlink signals S1', S2', S3' having different frequencies, and then amplifies them to a predetermined transmission power and transmits them from the GW antenna 22 to the relay station child device 31 of the HAPS 30 via the feeder link FL.

[0047] Relay station slave device 31 amplifies the multiple downlink signals S1', S2', S3' received from relay station master device 21, converts them to multiple downlink signals S1'', S2'', S3'' having the original service link frequency, performs serial / parallel conversion processing, and transmits them to each of the multiple cells 300(1), 300(2), 300(3) via service link SL.

[0048] In the wireless relay system 10, normally, a plurality of downlink signals S1', S2', S3' corresponding to each cell in the feeder link FL are transmitted with equal transmission power.

[0049] However, for example, as shown in FIG. 2, when the operation of a specific cell (cell 300(1) in the illustrated example) is stopped due to an equipment failure or the like, there is no need to relay the downlink signal corresponding to that cell (downlink signal S1' in the illustrated example) via the feeder link FL, at least until the operation is restored.

[0050] Also, for example, as shown in Fig. 3, depending on the flight path of HAPS 30, some cells (cell 300(3) in the illustrated example) may overlap with ground cell 700C of terrestrial base station 70. In such a case, it may be practical to temporarily suspend the operation of the cell. Even if the operation of some cells is suspended due to overlap with ground cell 700C in this way, there is no need to relay the downlink signal corresponding to that cell (downlink signal S3' in the illustrated example) via the feeder link FL.

[0051] In the wireless relay system 10 of the present embodiment, when the operation of some of the cells 300(1), 300(2), and 300(3) is stopped and it is no longer necessary to relay all of the downlink signals S1', S2', and S3' on the feeder link FL as illustrated in Fig. 2 and Fig. 3, the relay station parent device 21 distributes the power of the downlink signals corresponding to the cells whose operation has been stopped to the power of the downlink signals corresponding to the remaining cells other than the cells whose operation has been stopped. This power distribution makes it possible to increase the power of the downlink signals corresponding to the remaining cells other than the cells whose operation has been stopped, which are transmitted from the relay station parent device 21 to the relay station child device 31 via the feeder link FL, without increasing the total feeder link transmission power of the relay station parent device 21, and to improve the quality of the downlink signals.

[0052] 4 is a diagram showing an example of a configuration of main parts of the relay station parent device 21 and the relay station child device 31 of the wireless relay system 10 according to the embodiment. In FIG. 4, the relay station parent device 21 has a monitor / determiner 211, a parallel / serial converter 212, a power distributor 213, a frequency converter 214, and a power amplifier 215.

[0053] The monitoring and determining unit 211 functions as a monitoring unit that monitors the synchronization signals SS, which are known signals transmitted at regular time intervals from the base station 40, for the multiple cells 300(1), 300(2), and 300(3). The monitoring and determining unit 211 also functions as a determining unit that determines whether to suspend operation of a portion of the multiple cells 300(1), 300(2), and 300(3) (cell 300(1) in the example of FIG. 4) based on the power of the multiple synchronization signals SS. The monitoring and determining unit 211 notifies the power distributor 213 of the result of the determination.

[0054] In the case of, for example, the LTE-Advanced standard or the 5GNR standard, the synchronization signal SS monitored by the monitoring determination unit 211 may be a PSS (primary synchronization signal), an SSS (secondary synchronization signal), or both, which are set at a predetermined position in a radio frame 800 and periodically transmitted at a predetermined time from the base station 40 as shown in Fig. 5. The monitoring determination unit 211 may estimate the power of the synchronization signal SS based on correlation processing between a received signal received from the base station 40 and a replica of a known synchronization signal SS (PSS, SSS) of each cell.

[0055] In addition, the monitoring and determination unit 211 may calculate multiple correlation coefficients by performing correlation processing between the received signal from the base station 40 and a replica of the known synchronization signal SS (PSS, SSS) of each cell, and determine to suspend operation of some of the multiple cells based on the values ​​of the multiple correlation coefficients.

[0056] For example, when the power or correlation coefficient value of the synchronization signal SS corresponding to the cell 300 continues to be equal to or lower than a predetermined threshold value during a predetermined determination period (for example, 10 milliseconds, 20 milliseconds, several tens of seconds, or one minute), the monitoring determination unit 211 determines that the operation of the cell is stopped. Also, when the power or correlation coefficient value of the synchronization signal SS corresponding to the cell is greater than the threshold value even once during the predetermined determination period, the monitoring determination unit 211 determines that the cell is in operation.

[0057] The parallel / serial converter 212 performs parallel / serial conversion processing on a plurality of downlink signals S1, S2, S3 of the same frequency received from the base station 40, and generates a plurality of downlink signals S1', S2', S3' having mutually different frequencies.

[0058] When the operation of some of the multiple cells 300(1), 300(2), and 300(3) is suspended based on the result of the determination by the monitoring and determination unit 211, the power distribution unit 213 may distribute the power of the downlink signal (in the example of FIG. 4, downlink signal S1') corresponding to the suspended cell (in the example of FIG. 4, cell 300(1)) to the power of the downlink signals (in the example of FIG. 4, downlink signals S2', S3') corresponding to the remaining cells other than the suspended cell (in the example of FIG. 4, the multiple cells 300(2), 300(3)).

[0059] When it is determined that a part of the multiple cells (cell 300(1) in the example of FIG. 4) is out of operation, the power distribution unit 213 may evenly distribute surplus power generated by the outage of the cell to the remaining cells other than the out-of-operation cell (multiple cells 300(2) and 300(3) in the example of FIG. 4).

[0060] For example, the power distributor 213 sets the power Pn of the downlink signal (in the example of FIG. 4, downlink signal S1') corresponding to the out-of-operation cell (in the example of FIG. 4, cell 300(1)) to zero, and distributes the power Pn to the power of the downlink signal (in the example of FIG. 4, downlink signals S2', S3') corresponding to the remaining cells (in the example of FIG. 4, a plurality of cells 300(2), 300(3)) other than the out-of-operation cell. As a result, for example, the setting of the power Pd after distribution of the downlink signal (in the example of FIG. 4, downlink signals S2', S3') corresponding to the remaining cells (in the example of FIG. 4, a plurality of cells 300(2), 300(3)) is set to 1.5 times the normal power Pn.

[0061] The frequency conversion unit 214 converts the frequencies of the downlink signals S2', S3' after the power distribution unit 213 distributes the power from a frequency in the frequency band of the service link SL to a frequency in the frequency band of the feeder link FL.

[0062] The power amplifier 215 amplifies the power of the multiple downlink signals S2', S3' having a frequency in the frequency band of the feeder link FL by a predetermined power gain. The multiple downlink signals S2', S3' amplified by the power amplifier 215 are transmitted from the GW antenna 22 to the relay station slave unit 31 of the HAPS 30 via the feeder link FL.

[0063] The relay station slave unit 31 has a gain control unit 311 , a frequency conversion unit 312 , and a serial / parallel conversion unit 313 .

[0064] The gain control unit 311 amplifies a received signal including a plurality of downlink signals S1', S2', and S3' of the feeder link received from the relay station master unit 21 via the FL antenna, by using a low-noise amplifier controlled to a predetermined gain.

[0065] The frequency conversion unit 312 converts the frequency band of the feeder link of the received signal including the multiple downlink signals S2' and S3' output from the gain control unit 311 into the frequency band of the original service link.

[0066] The serial / parallel converter 313 converts the received signal including the multiple downlink signals S2', S3' in the frequency band of the service link output from the frequency converter 312 into multiple downlink signals S2'', S3'' having the same service link frequency. The multiple downlink signals S2'', S3'' having the same service link frequency are amplified by a predetermined power amplifier and then transmitted from the SL antenna via the service link SL toward the cells 300(2) and 300(3).

[0067] According to the wireless relay system 10 of FIG. 4, within the relay station parent device 21, it is determined whether some of the multiple cells 300(1), 300(2), and 300(3) are out of operation, and based on the result of the determination, the power of the downlink signal S1' corresponding to the out-of-operation cell 300(1) is distributed to the power of the downlink signals S2', S3' corresponding to the remaining cells other than the out-of-operation cell.

[0068] Fig. 6 is a diagram showing an example of a configuration of a main part of a wireless relay system 10 including a management device 60 according to an embodiment. In Fig. 6, the same components as those in Fig. 4 are denoted by the same reference numerals, and the description thereof will be omitted.

[0069] 6, the management device 60 includes an information acquisition unit 611 that acquires aerial position information of HAPS 30 in which a relay station slave unit 31 is installed, a determination unit 612 that determines whether to suspend operation of a portion of the multiple cells 300(1), 300(2), and 300(3) (cell 300(1) in the example of FIG. 6) based on the aerial position information of HAPS 30, and an information transmission unit 613 that transmits the result of the determination by the determination unit 612 (cell suspension information) to the relay station master unit 21.

[0070] The sky position information of the HAPS 30 is periodically transmitted from the communication unit 32 provided in the HAPS 30 to the management device 60, for example. The sky position information may include information on the current position of the HAPS 30 in the sky and the planned movement route (flight route information).

[0071] The information acquisition unit 611 may acquire the sky position information via a satellite line, or via a feeder link line multiplexed onto the feeder link FL and the relay station master unit 21.

[0072] In FIG. 6, the power distribution unit 213 of the relay station parent device 21 receives the result of the judgment (cell outage information) of the judgment unit 612 from the management device 60, and based on the result of the judgment (cell outage information), may distribute the power of the downlink signal S1' corresponding to the out-of-operation cell (cell 300(1) in the example of FIG. 6) to the power of the downlink signals S2', S3' corresponding to the remaining cells other than the out-of-operation cell (cells 300(2) and 300(3) in the example of FIG. 6).

[0073] In FIG. 6, when the determination unit 612 of the management device 60 determines that some of the multiple cells 300(1), 300(2), and 300(3) (cell 300(1) in the example of FIG. 6) are to be suspended, the information transmission unit 613 may transmit to the base station 40 a cell suspension command to suspend transmission of a downlink signal (downlink signal S1 corresponding to cell 300(1) in the example of FIG. 6) corresponding to the suspended cell (cell 300(1) in the example of FIG. 6).

[0074] According to the wireless relay system 10 of FIG. 6, the management device 60 determines whether some of the multiple cells 300(1), 300(2), and 300(3) are out of operation, and based on the result of the determination, the relay station parent device 21 distributes the power of the downlink signal S1' corresponding to the out-of-operation cell 300(1) to the power of the downlink signals S2', S3' corresponding to the remaining cells other than the out-of-operation cell.

[0075] Fig. 7 is a diagram showing another example of the configuration of the main parts of the wireless relay system 10 including the management device 60 according to the embodiment. Fig. 7 shows an embodiment in which the configurations of Fig. 4 and Fig. 6 are combined to determine a suspended cell in each of the relay station master device 21 and the management device 60. In Fig. 7, the same reference numerals are used for the configurations common to Figs. 4 to 6, and the description thereof will be omitted.

[0076] In FIG. 7, the power distribution unit 213 of the relay station parent device 21 distributes the power of the downlink signal corresponding to the suspended cell to the power of the downlink signal corresponding to the remaining cells other than the suspended cell based on the judgment result received from the management device 60 and the judgment result of the monitoring and judgment unit 211 of the relay station parent device 21.

[0077] For example, when the monitoring and determination unit 211 of the relay station parent device 21 determines that the operation of some of the multiple cells 300(1), 300(2), and 300(3) (cell 300(1) in the example of FIG. 4) has been suspended, the power distribution unit 213 distributes, based on the result of the determination received from the monitoring and determination unit 211, the power of the downlink signal (downlink signal S1' in the example of FIG. 7) corresponding to the suspended cell (cell 300(1) in the example of FIG. 7) to the power of the downlink signals (downlink signals S2', S3' in the example of FIG. 7) corresponding to the remaining cells other than the suspended cell (multiple cells 300(2) and 300(3) in the example of FIG. 7).

[0078] 7, when the determination unit 612 of the management device 60 determines to suspend operation of some of the multiple cells 300(1), 300(2), and 300(3) (cell 300(1) in the example of FIG. 7) based on the overhead position information of the HAPS 30, the power distribution unit 213 of the relay station parent device 21 receives the result of the determination by the determination unit 612 (cell suspension information) from the management device 60. Based on the result of the determination (cell suspension information) received from the management device 60, the power distribution unit 213 distributes the power of the downlink signal S1' corresponding to the suspended cell (cell 300(1) in the example of FIG. 7) to the power of the downlink signals S2' and S3' corresponding to the remaining cells other than the suspended cell (cells 300(2) and 300(3) in the example of FIG. 6).

[0079] As described above, according to the embodiment of the present disclosure, it is possible to increase the power of the downlink signal corresponding to the remaining cells other than the suspended cells, which is transmitted from the relay station parent device 21 to the relay station child device 31 via the feeder link FL, without increasing the total feeder link transmission power of the relay station parent device 21, thereby improving the quality of the downlink signal.

[0080] In addition, the wireless relay system disclosed herein can improve the quality of the downlink signal of the feeder link corresponding to the remaining cells other than the suspended cells when some of the multiple cells formed via the relay station sub-units in the sky are out of operation, thereby contributing to the achievement of Goal 9 of the Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote industry, innovation and infrastructure."

[0081] The process steps and components of the wireless relay system, relay station master, relay station slave, and management device described herein may be implemented by various means. For example, these processes and components may be implemented by hardware, firmware, software, or a combination thereof.

[0082] For hardware implementation, the processing units and other means used to realize the above steps and components in an entity (e.g., various wireless communication devices, Node B, terminals, 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 processors (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 in this specification, computers, or combinations thereof.

[0083] Also, for firmware and / or software implementation, the means such as processing units used to realize the above components may be implemented with programs (e.g., codes such as procedures, functions, modules, instructions, etc.) that execute the functions described herein. In general, any computer / processor readable medium tangibly embodying firmware and / or software codes may be used to implement the means such as processing units used to realize the above steps and components described herein. For example, the firmware and / or software codes may be stored in a memory and executed by a computer or processor, for example in a controller. The memory may be implemented within the computer or processor, or may be implemented externally to the processor. Also, the firmware and / or software codes may be stored in a computer or processor readable medium, such as a random access memory (RAM), a read-only memory (ROM), a non-volatile random access memory (NVRAM), a programmable read-only memory (PROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a floppy disk, a compact disk (CD), a digital versatile disk (DVD), a 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.

[0084] The medium may be a non-transitory recording medium. The code of the program may be in any format as long as it can be read and executed by a computer, a processor, or another device or machine, and the format is not limited to a specific 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.

[0085] Moreover, the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. [Explanation of symbols]

[0086] 10: Radio relay system 20: Gateway device (GW station) 21: Main station 22: GW Antenna 30: HAPS (flying object, floating object) 31: Relay station handset 32: Communications Department 40:Base station 41:Base station equipment 50: Terminal device 60: Management device 65: Network equipment 70: Terrestrial base station 211: Monitoring judgment unit 212: Serial conversion unit 213: Power distribution section 214: Frequency conversion section 215: Power amplifier 300: Cell 311: Gain control section 312: Frequency conversion section 313: Parallel conversion unit 611: Information acquisition department 612: Judgment section 613: Information transmission unit 700C: Ground cell 800: Wireless frame

Claims

1. A wireless relay system of a non-regenerative relay type, comprising a relay station master unit provided in a gateway device on land or sea, and a relay station slave unit provided in an aircraft or floating body in the sky, relaying wireless communications between a base station and terminal devices located in a plurality of cells via a feeder link between the relay station master unit and the relay station slave unit, The relay station master unit has a power distribution unit that distributes, when operation of a part of the plurality of cells is stopped, power of a downlink signal corresponding to a stopped cell to power of a downlink signal corresponding to a remaining cell other than the stopped cell. A radio relay system comprising:

2. In the wireless relay system of claim 1, The relay station master unit has a determination unit that determines whether to stop operation of a part of the plurality of cells, The power distribution unit of the relay station parent device distributes the power of a downlink signal corresponding to a suspended cell to the power of a downlink signal corresponding to a remaining cell other than the suspended cell based on a result of the determination by the determination unit. A radio relay system comprising:

3. In the wireless relay system of claim 2, the relay station master unit has a monitoring unit that monitors a plurality of synchronization signals transmitted from the base station at regular time intervals for the plurality of cells; The determination unit of the relay station master determines whether to suspend operation of a part of the plurality of cells based on power of the plurality of synchronization signals. A radio relay system comprising:

4. In the wireless relay system of claim 3, The monitoring unit of the relay station master device estimates powers of the plurality of synchronization signals based on a correlation process between a received signal received from the base station and a replica of the synchronization signal.

1. A radio relay system comprising:

5. In the wireless relay system of claim 2, the relay station master unit has a monitoring unit that monitors a plurality of synchronization signals transmitted from the base station at regular time intervals for the plurality of cells; The monitoring unit of the relay station master calculates a plurality of correlation coefficients by correlation processing between the received signal received from the base station and a replica of the synchronization signal, The determination unit of the relay station master determines to suspend operation of a part of the plurality of cells based on the values ​​of the plurality of correlation coefficients. A radio relay system comprising:

6. In the radio relay system according to any one of claims 3 to 5, The determination unit of the relay station master device When the power of the synchronization signal corresponding to the cell or the value of the correlation coefficient continues to be equal to or less than a predetermined threshold during a predetermined determination period, it is determined that the operation of the cell is stopped; When the power of the synchronization signal corresponding to the cell or the value of the correlation coefficient is greater than the threshold value at least once during the predetermined determination period, the cell is determined to be in operation. A radio relay system comprising:

7. In the wireless relay system of claim 1, A management device is provided, The management device includes: an information acquisition unit that acquires information on the sky position of the flying object or the floating object on which the relay station slave unit is installed; A determination unit that determines whether to suspend operation of a portion of the plurality of cells based on the sky position information of the flying object or the floating object; an information transmission unit that transmits a result of the determination by the determination unit to the relay station master device; The power distribution unit of the relay station parent device receives a result of the determination by the determination unit from the management device, and distributes the power of a downlink signal corresponding to a suspended cell to the power of a downlink signal corresponding to a remaining cell other than the suspended cell based on the result of the determination. A radio relay system comprising:

8. In the wireless relay system of claim 7, The sky position information includes information on the current position and planned movement route in the sky of the flying object or the floating object, A radio relay system comprising:

9. In the wireless relay system of claim 7, The information acquisition unit of the management device acquires the sky position information via a satellite line, or via a feeder link line between the relay station master and the relay station slave and the relay station master. A radio relay system comprising:

10. In the wireless relay system of claim 1, A management device is provided, The management device includes: an information acquisition unit that acquires information on the sky position of the flying object or the floating object on which the relay station slave unit is installed; A determination unit that determines whether to suspend operation of a portion of the plurality of cells based on the sky position information of the flying object or the floating object; an information transmission unit that transmits a result of the determination by the determination unit to the relay station master device; The relay station master unit includes: an information receiving unit that receives a result of the determination by the determining unit from the management device; A determination unit that determines whether or not a part of the plurality of cells is stopped operating, The power distribution unit of the relay station parent device distributes the power of a downlink signal corresponding to a suspended cell to the power of a downlink signal corresponding to a remaining cell other than the suspended cell, based on the result of the determination received from the management device and the result of the determination by the determination unit of the relay station parent device. A radio relay system comprising:

11. The wireless relay system of claim 10, the relay station master unit has a monitoring unit that monitors a plurality of synchronization signals transmitted from the base station at regular time intervals for the plurality of cells; The determination unit of the relay station master determines whether to suspend operation of a part of the plurality of cells based on power of the plurality of synchronization signals. A radio relay system comprising:

12. The wireless relay system of claim 11, The monitoring unit of the relay station master device estimates powers of the plurality of synchronization signals based on a correlation process between a received signal received from the base station and a replica of the synchronization signal. A radio relay system comprising:

13. The wireless relay system of claim 10, the relay station master unit has a monitoring unit that monitors a plurality of synchronization signals transmitted from the base station at regular time intervals for the plurality of cells; The monitoring unit of the relay station master calculates a plurality of correlation coefficients by correlation processing between the received signal received from the base station and a replica of the synchronization signal, The determination unit of the relay station master determines to suspend operation of a part of the plurality of cells based on the values ​​of the plurality of correlation coefficients. A radio relay system comprising:

14. 14. The wireless relay system according to claim 11, The determination unit of the relay station master device When the power of the synchronization signal corresponding to the cell or the value of the correlation coefficient continues to be equal to or less than a predetermined threshold during a predetermined determination period, it is determined that the operation of the cell is stopped; When the power of the synchronization signal corresponding to the cell or the value of the correlation coefficient is greater than the threshold value at least once during the predetermined determination period, the cell is determined to be in operation. A radio relay system comprising:

15. The wireless relay system of claim 10, The sky position information includes information on the current position and planned movement route in the sky of the flying object or the floating object, A radio relay system comprising:

16. The wireless relay system of claim 10, The information acquisition unit of the management device acquires the sky position information via a satellite line, or via a feeder link line between the relay station master and the relay station slave and the relay station master. A radio relay system comprising:

17. 17. A radio relay system according to claim 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 15 or 16, When it is determined that some of the cells are out of operation, the power distribution unit of the relay station parent device evenly distributes surplus power generated due to the outage of the cell to power of downlink signals corresponding to the remaining cells other than the out-of-operation cells. A radio relay system comprising:

18. A relay station master unit provided in a gateway device on land or sea, A non-regenerative repeater type wireless repeater system is formed by combining the relay station slave unit with a relay station slave unit installed on an aircraft or floating object in the sky, and a power distribution unit that distributes, when an operation of a part of a plurality of cells formed via the relay station slave device is stopped, power of a downlink signal corresponding to a stopped cell to power of a downlink signal corresponding to a remaining cell other than the stopped cell. A relay station master unit characterized by the above.

19. A management device in a non-regenerative relay type wireless relay system including a relay station master unit provided in a ground or sea gateway device and a relay station slave unit provided in an aircraft or floating object located in the sky, an information acquisition unit that acquires information on the sky position of the flying object or the floating object on which the relay station slave unit is installed; A determination unit that determines whether to suspend operation of a part of a plurality of cells formed via the relay station slave unit based on the sky position information of the flying object or the floating object; an information transmission unit that transmits a result of the determination by the determination unit to the relay station master; A management device comprising:

20. A non-regenerative relay method for relaying wireless communication between a base station and a terminal device located in a plurality of cells via a feeder link between a relay station master device provided in a ground or sea gateway device and a relay station slave device provided in an aircraft or floating object located in the sky, comprising: A wireless relay method comprising, when operation of some of the plurality of cells is suspended, distributing the power of a downlink signal corresponding to a suspended cell to the power of a downlink signal corresponding to the remaining cells other than the suspended cell.

21. A program executed by a computer or processor provided in a relay station master in a non-regenerative relay type wireless relay system including a relay station master provided in a ground or sea gateway device and a relay station slave provided in an aircraft or floating object located in the sky, comprising: A program comprising program code for distributing, when operation of a portion of a plurality of cells formed via the relay station slave device is stopped, the power of a downlink signal corresponding to a cell that has been stopped in operation to the power of a downlink signal corresponding to the remaining cells other than the cell that has been stopped in operation.

22. A program executed by a computer or processor provided in a management device in a non-regenerative relay type wireless relay system having a relay station master provided in a ground or sea gateway device and a relay station slave provided in an aircraft or floating object in the sky, comprising: A program code for acquiring information on the position of the flying object or the floating object in the sky on which the relay station slave unit is installed; A program code for determining whether or not to suspend operation of a part of a plurality of cells formed via the relay station slave unit based on the aerial position information of the flying object or the floating object; A program code for transmitting a result of the determination to the relay station master; A program comprising:

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