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

Abstract

This wireless relay system provides an improved downlink signal quality for the feeder link corresponding to the remaining cells (excluding the non-operational cells) when some of the multiple cells formed via the relay station slave units in the air become inoperable, without increasing the total feeder link transmission power of the relay station master unit. [Solution] In a non-regenerative relay type wireless relay system that relays wireless communication between a base station and terminal devices located in multiple cells via a feeder link between a relay station master unit installed on a gateway device on land or at sea and a relay station slave unit installed on an aircraft or floating object in the air, the relay station master unit has a power distribution unit that, when the operation of some of the multiple cells stops, distributes the power of the downlink signal corresponding to the cell that has stopped working to the power of the downlink signal corresponding to the remaining cells other than the cell that has stopped working.

Description

Technical Field

[0001] The present disclosure relates to wireless relaying using a non-regenerative relaying method.

Background Art

[0002] Conventionally, a wireless relay system using a non-regenerative relaying method is known that includes a relay master unit provided in a ground or marine gateway device and a relay slave unit provided in an aerial aircraft or floating body, and relays wireless communication between a base station and terminal devices of a plurality of cells via a feeder link between the relay master unit and the relay slave unit (see, for example, Patent Document 1). The relay slave unit performs wireless communication of a feeder link with the relay master unit and wireless communication of a service link with terminal devices of a plurality of cells formed toward the ground.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] A wireless relay system according to one aspect of the present disclosure includes a relay master unit provided in a ground or marine gateway device and a relay slave unit provided in an aerial aircraft or floating body, and is a wireless relay system using a non-regenerative relaying method that relays wireless communication between a base station and terminal devices located in a plurality of cells via a feeder link between the relay master unit and the relay slave unit. The relay master unit has a power distribution unit that distributes the power of a downlink signal corresponding to an operation stop cell to the power of downlink signals corresponding to the remaining cells other than the operation stop cell when a part of the operation of the plurality of cells stops.

[0005] In the wireless relay system, the relay station master unit has a determination unit that determines whether some of the plurality of cells are out of service, and the power distribution unit of the relay station master unit may, based on the determination result of the determination unit, distribute the power of the downlink signal corresponding to the out-of-service cell to the power of the downlink signal corresponding to the remaining cells other than the out-of-service cell.

[0006] In the wireless relay system, the relay station master unit has a monitoring unit that monitors a plurality of synchronization signals transmitted from the base station to the plurality of cells at regular time intervals, and the determination unit of the relay station master unit may determine whether to shut down 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 unit may estimate the power of the multiple synchronization signals based on correlation processing between the received signal received from the base station and a replica of the synchronization signal.

[0008] In the wireless relay system, the relay station master unit has a monitoring unit that monitors a plurality of synchronization signals transmitted from the base station to the plurality of cells at regular time intervals, the monitoring unit of the relay station master unit 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, and the determination unit of the relay station master unit may determine to shut down some of the plurality of cells based on the values ​​of the plurality of correlation coefficients.

[0009] In the wireless relay system, the determination unit of the relay station master unit may determine that the operation of a cell has stopped if, during a predetermined determination period, the power of the synchronization signal or the value of the correlation coefficient corresponding to the cell remains below a predetermined threshold, and determine that the cell is in operation if, at any point during the predetermined determination period, the power of the synchronization signal or the value of the correlation coefficient corresponding to the cell exceeds the threshold.

[0010] The wireless relay system may include a management device. The management device may include an information acquisition unit that acquires aerial position information of the aircraft or the floating body on which the relay station slave unit is installed, a determination unit that determines the deactivation of some of the plurality of cells based on the aerial position information of the aircraft or the floating body, and an information transmission unit that transmits the result of the determination unit to the relay station master unit. The power distribution unit of the relay station master unit may receive the result of the determination unit from the management device and, based on the result of the determination, distribute the power of the downlink signal corresponding to the deactivated cell to the power of the downlink signal corresponding to the remaining cells other than the deactivated cell.

[0011] In the aforementioned wireless relay system, the aerial position information may include information on the current position and planned route of the aircraft 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 link, or via the feeder link line between the relay station master unit and the relay station slave unit and the relay station master unit.

[0013] In the wireless relay system, the determination unit of the relay station master unit and the power distribution unit of the relay station master unit may, based on the result of the determination received from the management device and the result of the determination unit of the relay station master unit, distribute the power of the downlink signal corresponding to the out-of-operation cell to the power of the downlink signal corresponding to the remaining cells other than the out-of-operation cell.

[0014] In the aforementioned wireless relay system, if the power distribution unit of the relay station master unit determines that some of the multiple cells are out of service, it may equally distribute the surplus power generated as a result of the out-of-service cells to the power of the downlink signals corresponding to the remaining cells other than the out-of-service cells.

[0015] A relay station master according to another aspect of this disclosure is a relay station master installed on a gateway device on land or at sea. This relay station master is combined with relay station slaves installed on an airborne aircraft or floating vehicle to constitute a non-regenerative relay wireless relay system. The relay station master has a power distribution unit that, when the operation of some of the multiple cells formed via the relay station slaves stops, distributes the power of the downlink signal corresponding to the inoperable cell to the power of the downlink signal corresponding to the remaining cells other than the inoperable cell.

[0016] A management device according to yet another aspect of this disclosure is a management device in a non-regenerative relay wireless relay system comprising a relay station master unit installed on a gateway device on land or at sea and a relay station slave unit installed on an aircraft or floating object located in the air. This management device comprises an information acquisition unit that acquires aerial position information of the aircraft or floating object on which the relay station slave unit is installed, a determination unit that determines the deactivation of a portion of a plurality of cells formed via the relay station slave unit based on the aerial position information of the aircraft or floating object, and an information transmission unit that transmits the determination result of the determination unit to the relay station master unit.

[0017] A method relating to yet another aspect of this disclosure is a non-regenerative relay wireless relay method that relays wireless communication between a base station and terminal devices located in multiple cells via a relay station master unit installed on a gateway device on land or at sea and a relay station slave unit installed on an aircraft or floating object located in the air. This wireless relay method includes, when some of the multiple cells cease operation, distributing the power of the downlink signal corresponding to the inoperable cell to the power of the downlink signal corresponding to the remaining cells other than the inoperable cell.

[0018] A program relating to yet another aspect of this disclosure is a program executed on a computer or processor installed in a relay station master unit in a non-regenerative relay wireless relay system comprising a relay station master unit installed in a gateway device on land or at sea and relay station slave units installed in an aircraft or floating object located in the air. The program includes program code for distributing the power of the downlink signal corresponding to a cell that has stopped operating when some of the cells formed via the relay station slave units stop operating, to the power of the downlink signal corresponding to the remaining cells that do not stop operating.

[0019] A program relating to yet another aspect of this disclosure is a program executed on a computer or processor provided in a management device for a non-regenerative relay wireless relay system comprising a relay station master unit provided on a gateway device on land or at sea and relay station slave units provided on an airborne aircraft or floating object. The program includes program code for acquiring airborne position information of the aircraft or floating object on which the relay station slave units are provided, program code for determining the deactivation of a portion of a plurality of cells formed via the relay station slave units based on the airborne position information of the aircraft or floating object, and program code for transmitting the result of the determination to the relay station master unit.

[0020] Furthermore, the program of this disclosure may include a trained model used for machine learning. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 shows an example of the overall configuration of a wireless relay system according to the present disclosure. [Figure 2] Figure 2 shows an example of a challenge in relaying downlink signals in a wireless relay system. [Figure 3] Figure 3 shows another example of the challenges encountered when relaying downlink signals in a wireless relay system. [Figure 4]FIG. 4 is a diagram showing an example of the main configuration of the relay station master unit and the relay station slave unit of the wireless relay system according to the embodiment. [Figure 5] FIG. 5 is a diagram showing an example of a synchronization signal in a wireless frame of a transmission signal transmitted from a base station. [Figure 6] FIG. 6 is a diagram showing an example of the main configuration of a wireless relay system including a management device according to the embodiment. [Figure 7] FIG. 7 is a diagram showing another example of the main configuration of a wireless relay system including a management device according to the embodiment.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Each figure in the drawings only schematically shows the shape, size, positional relationship, correspondence relationship, configuration, processing, steps, procedures, etc. to the extent that the content of the present disclosure can be understood. Therefore, the present disclosure is not limited to only the shape, size, positional relationship, correspondence relationship, configuration, processing, steps, and procedures illustrated in each figure. Also, the numerical values exemplified in the present disclosure are only preferred examples, and thus the present disclosure is not limited to the exemplified numerical values.

[0023] A system according to an embodiment of the present disclosure is a wireless relay system that can improve the quality of the downlink signal of the feeder link corresponding to the remaining cells other than the operation stop cells by distributing the transmission power to the remaining cells on the feeder link when a part of the operation of a plurality of cells formed via the relay station slave unit in the air stops. The wireless relay system according to the present embodiment is suitable for realizing a three-dimensional network in mobile communications conforming to, for example, the LTE (Long Term Evolution)-Advanced standard, or in next-generation standards such as the 5th generation (hereinafter also referred to as "5GNR") that support simultaneous connection to a large number of terminal devices and low latency.

[0024] Figure 1 shows an example of the overall configuration of the wireless relay system 10 according to the embodiment. The wireless relay system 10 comprises a relay station master unit 21 installed on a gateway device 20 on land or at sea, and a relay station slave unit 31 installed on an airborne aircraft or floating vehicle, and is a non-regenerative relay type wireless relay system that relays wireless communication between a base station 40 and terminal devices 50 located in multiple cells 300C(1) to 300C(3) via a feeder link FL between the relay station master unit 21 and the relay station slave unit 31.

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

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

[0027] Because HAPS30 flies at an altitude lower than that of typical satellites but higher than ground and sea base stations, it can achieve high line-of-sight coverage while having less propagation loss than satellite communications. Due to this characteristic, it is also possible to provide communication services from HAPS30 to user equipment such as ground or sea cellular mobile terminals (mobile stations) 50. By providing communication services from HAPS30, a large area that was previously covered by numerous ground or sea base stations can be covered at once with a small number of HAPS30s, offering the advantage of providing low-cost and stable communication services.

[0028] The HAPS30 relay station slave unit 31 uses a service link antenna (hereinafter referred to as the "SL antenna") to form multiple beams directed toward the ground (or sea surface) for wireless communication with the user's terminal equipment (hereinafter referred to as the "UE" (user equipment)) 50, thereby forming multiple cells (also called "HAPS cells") 300C(1) to 300C(3) capable of wireless communication with U50. The radius of the service area (also called the "HAPS service area") consisting of the footprints of these cells on land (or sea) is, for example, several tens to 100 kilometers.

[0029] In this embodiment, the relay station slave unit 31 of the HAPS30 forms a 3-cell 300C(1) to 300C(3), but the multiple cells formed by the relay station slave unit 31 may be 2-cell, 4-cell, 5-cell, 6-cell, or 7-cell, or 8 or more cells.

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

[0031] The HAPS30 repeater unit 31 is a repeater unit that communicates wirelessly with a repeater master unit (repeater master unit) 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 base station 40 on land (or at sea). The repeater unit 31 is connected to the core network of the mobile communication network via a GW station 20, base station 40, and network device 65 installed on land or at sea, which are capable of wireless communication via a feeder link antenna (hereinafter referred to as an "FL antenna").

[0032] The feeder link FL communication between the HAPS20 relay station slave unit 31 and the GW station 20 relay station master unit 21 may be performed by wireless communication using radio waves such as microwave, millimeter wave, or submillimeter wave, or by optical communication using laser light or the like.

[0033] The GW station 20 may control its own antenna (hereinafter referred to as "GW antenna") 22 to track the HAPS 30 as it moves through the air. By having the GW antenna 22 track the HAPS 30, even when using a GW antenna 22 with high directivity such as a parabolic antenna, the deterioration of the communication quality of the feeder link FL due to the movement of the HAPS 30 can be suppressed.

[0034] Base station 40 is equipped with multiple base station devices (e.g., eNodeB, gNodeB) 41(1) to 41(3) to correspond to multiple 300C(1) to 300C(3). Each of the base station devices 41(1) to 41(3), for example in the case of an LTE eNodeB, consists of a remote radio head (RRH, also called a remote radio unit (RRU)) and a base band unit (BBU). The RRH and BBU may be connected by optical fiber lines and placed at a distance from each other. Alternatively, multiple BBUs may be consolidated and installed in one location.

[0035] Each of the RRHs of the multiple base station devices 41(1) to 41(3) is equipped with, for example, a quadrature modulation / demodulation unit, a transmitter, a receiver, a power amplifier (PA), and a low-noise receiver (LNA), and is connected to the GW station 20. The quadrature modulation / demodulation unit quadrature modulates and demodulates the OFDM signal processed by the BBU, converting it into an analog signal (RF signal). The transmitter converts the frequency of the RF signal generated by the quadrature modulation / demodulation unit into a frequency to be transmitted as radio waves. The receiver converts the frequency of the high-frequency signal of the received radio waves into a frequency to be processed by the quadrature modulation / demodulation unit. The power amplifier (PA) power-amplifies the RF signal generated by the transmitter. The low-noise receiver (LNA) amplifies the received weak radio waves and passes them to the receiver.

[0036] Each of the BBUs (Baseband Units) of the multiple base station devices 41(1) to 41(3) comprises, for example, a base station control unit, a transmission path interface unit, a timing control unit, and a baseband unit, and is connected to the core network of the mobile communication network via a predetermined interface (for example, the S1 interface). The base station control unit controls the entire base station and performs call control protocols and control monitoring. The transmission path interface unit is connected to a packet transmission path such as Ethernet® with the core network, and processes a predetermined protocol to send and receive IP packets. The timing control unit generates various clocks used inside the base station based on a reference clock extracted from signals received via the packet transmission path or from GNSS (Global Navigation Satellite System) signals received from artificial satellites. The baseband unit performs conversion (modulation / demodulation) between IP packets sent and received through the transmission path interface unit and OFDM signals (baseband signals), which are radio signals.

[0037] Each HAPS30 may autonomously control its own levitation and movement (flight) and processing at the relay station slave unit 31 by executing a control program in a control unit consisting of a computer or the like that is built inside. For example, each HAPS20 may acquire its own current location information (e.g., GPS location information), pre-stored location control information (e.g., flight schedule information), and location information of other HAPS30 located in the vicinity, and autonomously control its levitation and movement (flight) and processing at the relay station slave unit 31 based on this information.

[0038] Furthermore, the levitation and movement (flight) of each HAPS30 and the processing at the relay station slave unit 31 may be controlled by a management device (also called a "remote control device" or "central control server") located in a communication center or the like connected to the core network of the mobile communication network. The management device can be composed of, for example, a computer device such as a PC or a server. In this case, the HAPS30 is equipped with 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 of the management device. The control communication unit may be assigned terminal identification information (e.g., an IP address, a telephone number, etc.) so that it can communicate with the management device. The MAC address of the communication interface may be used to identify the control communication unit of the HAPS30.

[0039] The transmission and reception of control information and monitoring information between HAPS30 and the management device can be performed, for example, via an LTE communication line that passes through the core network of a mobile communication network, the base station 40, and the GW station 20. Alternatively, the transmission and reception of control information and monitoring information may be performed using a satellite link of mobile communication via an artificial satellite, or using a satellite link via the Internet and an artificial satellite.

[0040] The monitoring information transmitted from HAPS30 may include at least one of the following: information regarding the levitation movement (flight) of the HAPS itself or surrounding HAPS and processing at the relay station slave unit 31; monitoring information including the received level, which is the received power of the feeder link between HAPS30 and GW station 20; and information regarding the status of HAPS30 and observation data acquired by various sensors. The monitoring information may also include at least one of the following: the current position and attitude information of HAPS40, flight path information (flight schedule information, flight route history information), airspeed, ground speed and thrust direction, wind speed and direction of the airflow around HAPS20, and atmospheric pressure and temperature around HAPS30. The control information may include flight information such as the target flight route information of HAPS30.

[0041] HAPS30 and the management device may acquire weather forecast information for the area including the feeder link radio propagation path, maintenance schedule information for GW station 20 or base station 40, received level monitor information for the feeder link with GW station 20 measured by HAPS30, flight path information of HAPS30, current location information and attitude information of HAPS30. This information may be obtained, for example, from a server of the core network (mobile communication network) or an Internet server that manages each piece of information. The management device may also acquire maintenance schedule information for GW station 20 or base station 40 from GW station 20 or base station 40 via the core network of the mobile communication network using a predetermined interface (for example, the LTE S1 interface), or from a server that manages GW station 20 or base station 40.

[0042] The duplexing method for the uplink and downlink of the service link SL wireless communication between the relay station slave unit 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. Furthermore, the access method for the service link SL wireless communication between the relay station slave unit 31 and the terminal device 50 is not limited to a specific method, and may be, for example, an FDMA (Frequency Division Multiple Access) method, a TDMA (Time Division Multiple Access) method, a CDMA (Code Division Multiple Access) method, or an OFDMA (Orthogonal Frequency Division Multiple Access) method. In addition, the wireless communication may utilize MIMO (Multi-Input and Multi-Output) technology, which has functions such as diversity coding, transmit beamforming, and spatial division multiplexing (SDM), and can increase the transmission capacity per unit frequency by simultaneously using multiple antennas for both transmission and reception. Furthermore, the MIMO technology may be SU-MIMO (Single-User MIMO) technology, in which one base station transmits multiple signals to one terminal device at the same time and frequency, or MU-MIMO (Multi-User MIMO) technology, in which one base station transmits signals to multiple different terminal devices at the same time and frequency.

[0043] In the following embodiments, the HAPS 30, which has a relay station slave unit 31 that communicates wirelessly with the terminal device 50, is illustrated and described as a solar-powered plane type HAPS; however, the HAPS 30 may also be an unmanned airship type HAPS. Furthermore, the following embodiments can be similarly applied to airborne communication relay devices consisting of other aircraft or floating bodies other than HAPS.

[0044] Furthermore, the link between HAPS30 and base station 40 via GW station 20 is called the "feeder link" (FL), and the link between HAPS30 and terminal equipment 50 is called the "service link" (SL). In particular, the section between HAPS30 and GW station 20 is called the "feeder link radio section." Also, the downlink of communication from GW station 20 to terminal equipment 50 via HAPS30 is called the "forward link," and the uplink of communication from terminal equipment 50 to GW station 20 via HAPS30 is called the "reverse link."

[0045] In the wireless relay system 10 configured as described above, multiple downlink signals S1, S2, and S3 of the same frequency for the service links corresponding to multiple cells 300(1), 300(2), and 300(3) are output from multiple base station devices 41(1), 41(2), and 41(3) of the base station 40 and received by the relay station master unit 21 of the GW station 20.

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

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

[0048] In the wireless relay system 10, under normal circumstances, multiple downlink signals S1', S2', and S3' corresponding to each cell in the feeder link FL are transmitted with equal transmission power to each other.

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

[0050] Furthermore, as shown in Figure 3, depending on the flight path of HAPS30, some cells (cell 300(3) in the illustrated example) may overlap with ground cell 700C of ground base station 70. In such cases, it is conceivable in practical operation to temporarily suspend the operation of the affected cell. Even when the operation of some cells is suspended due to overlap with ground cell 700C, there is no longer a need to relay the downlink signal corresponding to that cell (downlink signal S3' in the illustrated example) via feeder link FL.

[0051] In the wireless relay system 10 of this embodiment, as illustrated in Figures 2 and 3, when some of the multiple cells 300(1), 300(2), and 300(3) become inoperable and it is no longer necessary to relay all of the multiple downlink signals S1', S2', and S3' via the feeder link FL, the relay station master unit 21 distributes the power of the downlink signals corresponding to the inoperable cells to the power of the downlink signals corresponding to the remaining cells other than the inoperable cells. This power distribution allows the power of the downlink signals corresponding to the remaining cells other than the inoperable cells, transmitted from the relay station master unit 21 to the relay station slave unit 31 via the feeder link FL, to be increased without increasing the total feeder link transmission power of the relay station master unit 21, thereby improving the quality of the downlink signals.

[0052] Figure 4 shows an example of the main components of the relay station master unit 21 and relay station slave unit 31 of the wireless relay system 10 according to the embodiment. In Figure 4, the relay station master unit 21 has a monitoring and determination unit 211, a parallel / series conversion unit 212, a power distribution unit 213, a frequency conversion unit 214, and a power amplifier 215.

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

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

[0055] Furthermore, the monitoring and determination unit 211 may calculate multiple correlation coefficients by correlating the received signal received from the base station 40 with a replica of the known synchronization signal SS (PSS, SSS) of each cell, and determine the deactivation of some of the cells based on the values ​​of the multiple correlation coefficients.

[0056] For example, the monitoring and determination unit 211 determines that a cell is out of operation if, during a predetermined determination period (e.g., 10 milliseconds, 20 milliseconds, several tens of seconds, or 1 minute), the power or correlation coefficient value of the synchronization signal SS corresponding to the cell remains below a predetermined threshold. The monitoring and determination unit 211 also determines that a cell is in operation if, during the predetermined determination period, the power or correlation coefficient value of the synchronization signal SS corresponding to the cell exceeds the threshold at any point.

[0057] The parallel / series conversion unit 212 performs parallel / series conversion processing on multiple downlink signals S1, S2, and S3 of the same frequency received from the base station 40 to generate multiple downlink signals S1', S2', and S3' having different frequencies.

[0058] Based on the determination result of the monitoring and determination unit 211, if some of the multiple cells 300(1), 300(2), and 300(3) stop operating, the power distribution unit 213 may distribute the power of the downlink signal (downlink signal S1' in the example of Figure 4) corresponding to the cell that has stopped operating (cell 300(1) in the example of Figure 4) to the power of the downlink signals (downlink signals S2', S3' in the example of Figure 4) corresponding to the remaining cells other than the cell that has stopped operating (multiple cells 300(2), 300(3) in the example of Figure 4).

[0059] If the power distribution unit 213 determines that a portion of the multiple cells (in the example in Figure 4, cell 300(1)) is out of service, it may distribute the surplus power generated as a result of the out-of-service cell to the remaining cells other than the out-of-service cell (in the example in Figure 4, multiple cells 300(2), 300(3)).

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

[0061] The frequency conversion unit 214 converts the frequencies of the downlink signals S2' and S3', which have been distributed by the power distribution unit 213, from the frequency band of the service link SL to the frequency band of the feeder link FL.

[0062] The power amplifier 215 amplifies the power of multiple downlink signals S2', S3' having frequencies 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 HAPS 30 relay station slave unit 31 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 series / parallel conversion unit 313.

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

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

[0066] The series / parallel conversion unit 313 converts the received signal, which includes multiple downlink signals S2', S3' in the service link frequency band output from the frequency conversion unit 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 to cells 300(2) and 300(3) via the service link SL.

[0067] According to the wireless relay system 10 in Figure 4, the relay station master unit 21 determines whether some of the multiple cells 300(1), 300(2), and 300(3) are out of service. Based on the result of this determination, the power of the downlink signal S1' corresponding to the out-of-service cell 300(1) is distributed to the power of the downlink signals S2' and S3' corresponding to the remaining cells that are not out of service.

[0068] Figure 6 shows an example of the main components of a wireless relay system 10 equipped with a management device 60 according to this embodiment. In Figure 6, components common to Figure 4 are denoted by the same reference numerals and their descriptions are omitted.

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

[0070] The aerial position information of HAPS30 is periodically transmitted, for example, from the communication unit 32 installed in HAPS30 to the management device 60. The aerial position information may include the current position of HAPS30 in the air and information on the planned flight path (flight path information).

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

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

[0073] In Figure 6, if 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 Figure 6) are shut down, the information transmission unit 613 may transmit a cell shutdown command to the base station 40 to stop transmitting the downlink signal (downlink signal S1 corresponding to cell 300(1) in the example of Figure 6) corresponding to the shut-down cell (cell 300(1) in the example of Figure 6).

[0074] According to the wireless relay system 10 in Figure 6, the management device 60 determines that some of the multiple cells 300(1), 300(2), and 300(3) are out of service. Based on the result of this determination, the relay station master unit 21 distributes the power of the downlink signal S1' corresponding to the out-of-service cell 300(1) to the power of the downlink signals S2' and S3' corresponding to the remaining cells other than the out-of-service cell.

[0075] Figure 7 shows another example of the main components of a wireless relay system 10 equipped with a management device 60 according to the embodiment. Figure 7 is an embodiment in which the configuration of Figure 4 and the configuration of Figure 6 are combined, and the relay station master unit 21 and the management device 60 each determine which cells are out of service. In Figure 7, components common to Figures 4 to 6 are denoted by the same reference numerals and their descriptions are omitted.

[0076] In Figure 7, the power distribution unit 213 of the relay station master unit 21 distributes the power of the downlink signal corresponding to the out-of-operation cell to the power of the downlink signal corresponding to the remaining cells other than the out-of-operation cell, based on the determination result received from the management device 60 and the determination result from the monitoring and determination unit 211 of the relay station master unit 21.

[0077] For example, if the monitoring and determination unit 211 of the relay station master unit 21 determines that some of the multiple cells 300(1), 300(2), and 300(3) (cell 300(1) in the example of Figure 4) have stopped operating, the power distribution unit 213, based on the determination received from the monitoring and determination unit 211, distributes the power of the downlink signal (downlink signal S1' in the example of Figure 7) corresponding to the out-of-operation cell (cell 300(1) in the example of Figure 7) to the power of the downlink signals (downlink signals S2', S3' in the example of Figure 7) corresponding to the remaining cells other than the out-of-operation cell (multiple cells 300(2), 300(3) in the example of Figure 7).

[0078] Furthermore, in Figure 7, if 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 Figure 7) have been shut down based on the aerial position information of the HAPS 30, the power distribution unit 213 of the relay station master unit 21 receives the result of the determination unit 612's determination (cell shutdown information) from the management device 60. Based on the result of the determination (cell shutdown information) received from the management device 60, the power distribution unit 213 distributes the power of the downlink signal S1' corresponding to the shut-down cell (cell 300(1) in the example of Figure 7) to the power of the downlink signals S2' and S3' corresponding to the remaining cells other than the shut-down cell (cells 300(2) and 300(3) in the example of Figure 6).

[0079] As described above, according to the embodiments of this disclosure, it is possible to increase the power of the downlink signal corresponding to the remaining cells other than the deactivated cells transmitted from the relay station master unit 21 to the relay station slave unit 31 via the feeder link FL without increasing the total feeder link transmission power of the relay station master unit 21, thereby improving the quality of the downlink signal.

[0080] Furthermore, 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 inoperable cells when some of the multiple cells formed via the relay station slave units in the air become inoperable, thereby contributing to the achievement of Sustainable Development Goal (SDG) 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

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

[0082] With respect to hardware implementation, means such as processing units used to realize the above processes and components in a physical entity (e.g., various wireless communication devices, Node B, terminals, hard disk drive devices, or optical disc drive devices) may be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, computers, or combinations thereof.

[0083] Furthermore, with respect to the firmware and / or software implementation, means such as processing units used to realize the above-mentioned components may be implemented in the form of a program (e.g., code such as procedures, functions, modules, instructions, etc.) that performs the functions described herein. Generally, any computer / processor-readable medium that clearly embodies the firmware and / or software code may be used to implement means such as processing units used to realize the above-mentioned processes and components as described herein. For example, the firmware and / or software code may be stored in memory in a control device, for example, and executed by a computer or processor. That memory may be implemented inside the computer or processor, or it may be implemented outside the processor. Also, the firmware and / or software code may be stored in a computer or processor-readable medium such as random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), electrically erasable PROM (EEPROM), flash memory, floppy disks, compact disks (CDs), digital versatile disks (DVDs), magnetic or optical data storage devices, etc. The code may be executed by one or more computers or processors, and the computers or processors may be made to perform functional embodiments as described herein.

[0084] Furthermore, the medium may be a non-temporary recording medium. Also, the program code may be readable and executable by a computer, processor, or other device or machine, and its format is not limited to a specific format. For example, the program code may be source code, object code, or binary code, or it may be a mixture of two or more of these codes.

[0085] Furthermore, the descriptions of embodiments disclosed herein are provided to enable those skilled in the art to manufacture or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the general principles defined herein are applicable to other variations without departing from the spirit or scope of the disclosure. Therefore, the disclosure is not limited to the examples and designs described herein, but should be accepted in the broadest sense that conforms to the principles and novel features disclosed herein. [Explanation of Symbols]

[0086] 10: Wireless relay system 20: Gateway device (GW station) 21: Relay station master unit 22: GW Antenna 30: HAPS (Flying Objects, Lifting Objects) 31: Relay station sub-unit 32: Communications Department 40:Base station 41:Base station equipment 50: Terminal device 60: Management device 65: Network device 70: Ground 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 Unit 312: Frequency conversion unit 313: Parallel conversion unit 611: Information acquisition department 612: Judgment section 613: Information Transmission Department 700C: Ground cell 800: Wireless Frame

Claims

1. A non-regenerative relay wireless relay system comprising a relay station master unit installed on a gateway device on land or at sea, and a relay station slave unit installed on an aerial aircraft or floating device, which relays wireless communication between a base station and terminal devices located in multiple 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, when the operation of some of the multiple cells stops, distributes the power of the downlink signal corresponding to the cell that has stopped working to the power of the downlink signal corresponding to the remaining cells other than the cell that has stopped working. A wireless relay system characterized by the following features.

2. In the wireless relay system of claim 1, The relay station master unit has a determination unit that determines whether to stop the operation of some of the multiple cells. The power distribution unit of the relay station master unit distributes the power of the downlink signal corresponding to the out-of-operation cell to the power of the downlink signal corresponding to the remaining cells other than the out-of-operation cell, based on the determination result of the determination unit. A wireless relay system characterized by the following features.

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 to the plurality of cells at regular time intervals, The determination unit of the relay station master unit determines the shutdown of some of the multiple cells based on the power of the multiple synchronization signals. A wireless relay system characterized by the following features.

4. In the wireless relay system of claim 3, The monitoring unit of the relay station base station estimates the power of the multiple synchronization signals based on correlation processing between the received signal received from the base station and the replica of the synchronization signal. A wireless relay system characterized by the following features.

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 to the plurality of cells at regular time intervals, The monitoring unit of the relay station master unit calculates multiple correlation coefficients by performing correlation processing between the received signal received from the base station and the replica of the synchronization signal. The determination unit of the relay station master unit determines to stop the operation of some of the multiple cells based on the values ​​of the multiple correlation coefficients. A wireless relay system characterized by the following features.

6. In a wireless relay system according to any one of claims 3 to 5, The determination unit of the relay station master unit is If, during a predetermined determination period, the power of the synchronization signal corresponding to the cell or the value of the correlation coefficient remains below a predetermined threshold, it is determined that the operation of the cell has stopped. If, during the predetermined determination period, the power of the synchronization signal corresponding to the cell or the value of the correlation coefficient is greater than the threshold at any point, it is determined that the cell is in operation. A wireless relay system characterized by the following features.

7. In the wireless relay system of claim 1, Equipped with a management device, The aforementioned control device is An information acquisition unit that acquires the aerial position information of the flying object or the floating object on which the relay station slave unit is installed, A determination unit that determines the deactivation of some of the multiple cells based on the aerial position information of the aircraft or the levitation unit, The relay station master unit has an information transmission unit that transmits the result of the determination unit's determination to the master unit, The power distribution unit of the relay station master unit receives the result of the determination unit's determination from the management device, and based on the result of the determination, distributes the power of the downlink signal corresponding to the out-of-operation cell to the power of the downlink signal corresponding to the remaining cells other than the out-of-operation cell. A wireless relay system characterized by the following features.

8. In the wireless relay system of claim 7, The aerial position information includes the current position and planned movement path above the aircraft or the levitation device. A wireless relay system characterized by the following features.

9. In the wireless relay system of claim 7, The information acquisition unit of the management device acquires the aerial position information via a satellite link, or via the feeder link line between the relay station master unit and the relay station slave unit and the relay station master unit. A wireless relay system characterized by the following features.

10. In the wireless relay system of claim 1, Equipped with a management device, The aforementioned control device is An information acquisition unit that acquires the aerial position information of the flying object or the floating object on which the relay station slave unit is installed, A determination unit that determines the deactivation of some of the multiple cells based on the aerial position information of the aircraft or the levitation body, The relay station master unit has an information transmission unit that transmits the result of the determination unit's determination to the master unit, The aforementioned relay station master unit is An information receiving unit that receives the result of the determination unit's determination from the management device, It includes a determination unit that determines whether to stop the operation of some of the aforementioned plurality of cells, The power distribution unit of the relay station master unit distributes the power of the downlink signal corresponding to the out-of-operation cell to the power of the downlink signal corresponding to the remaining cells other than the out-of-operation cell, based on the result of the determination received from the management device and the result of the determination unit of the relay station master unit. A wireless relay system characterized by the following features.

11. In 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 to the plurality of cells at regular time intervals, The determination unit of the relay station master unit determines the shutdown of some of the multiple cells based on the power of the multiple synchronization signals. A wireless relay system characterized by the following features.

12. In the wireless relay system of claim 11, The monitoring unit of the relay station base station estimates the power of multiple synchronization signals based on correlation processing between the received signal received from the base station and the replica of the synchronization signal. A wireless relay system characterized by the following features.

13. In 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 to the plurality of cells at regular time intervals, The monitoring unit of the relay station master unit calculates multiple correlation coefficients by performing correlation processing between the received signal received from the base station and the replica of the synchronization signal. The determination unit of the relay station master unit determines to stop the operation of some of the multiple cells based on the values ​​of the multiple correlation coefficients. A wireless relay system characterized by the following features.

14. In a wireless relay system according to any one of claims 11 to 13, The determination unit of the relay station master unit is If, during a predetermined determination period, the power of the synchronization signal corresponding to the cell or the value of the correlation coefficient remains below a predetermined threshold, it is determined that the operation of the cell has stopped. If, during the predetermined determination period, the power of the synchronization signal corresponding to the cell or the value of the correlation coefficient is greater than the threshold at any point, it is determined that the cell is in operation. A wireless relay system characterized by the following features.

15. In the wireless relay system of claim 10, The aerial position information includes the current position and planned movement path above the aircraft or the levitation device. A wireless relay system characterized by the following features.

16. In the wireless relay system of claim 10, The information acquisition unit of the management device acquires the aerial position information via a satellite link, or via the feeder link line between the relay station master unit and the relay station slave unit and the relay station master unit. A wireless relay system characterized by the following features.

17. In the wireless relay system of claim 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 15, or 16, When the power distribution unit of the relay station master unit determines that some of the multiple cells are out of service, it distributes the surplus power generated as a result of the out-of-service cells to the power of the downlink signal corresponding to the remaining cells other than the out-of-service cells. A wireless relay system characterized by the following features.

18. A relay station master unit installed on a land or sea gateway device, It is combined with a relay station substation installed on an airborne or floating object to form a non-regenerative relay wireless relay system. When the operation of some of the multiple cells formed via the relay station slave unit stops, the power distribution unit distributes the power of the downlink signal corresponding to the cell that has stopped working to the power of the downlink signal corresponding to the remaining cells other than the cell that has stopped working. A relay station master unit characterized by the following features.

19. A management device for a non-regenerative relay wireless relay system comprising a relay station master unit installed on a gateway device on land or at sea and a relay station slave unit installed on an aircraft or floating object located in the air, An information acquisition unit that acquires the aerial position information of the flying object or the floating object on which the relay station slave unit is installed, A determination unit that determines the deactivation of a portion of the multiple cells formed via the relay station slave unit based on the aerial position information of the flying object or the floating object, An information transmission unit that transmits the result of the determination unit's determination to the relay station master unit, A management device characterized by comprising:

20. A non-regenerative relay wireless relay method that relays wireless communication between a base station and terminal devices located in multiple cells via a feeder link between a relay station master unit installed on a gateway device on land or at sea and a relay station slave unit installed on an aircraft or floating object located in the air, A wireless relay method characterized by including, when the operation of some of the above-mentioned multiple cells is stopped, distributing the power of the downlink signal corresponding to the cell that is not in operation to the power of the downlink signal corresponding to the remaining cells other than the cell that is not in operation.

21. A program executed on a computer or processor installed in a relay station master unit in a non-regenerative relay wireless relay system comprising a relay station master unit installed in a gateway device on land or at sea and a relay station slave unit installed in an aircraft or floating object located in the air, A program characterized by including program code for distributing the power of the downlink signal corresponding to a cell that has stopped operating to the power of the downlink signal corresponding to the remaining cells that have not stopped operating, in the event that some of the cells formed via the relay station slave unit stop operating.

22. A program executed on a computer or processor installed in a management device of a non-regenerative relay wireless relay system comprising a relay station master unit installed on a gateway device on land or at sea and a relay station slave unit installed on an aircraft or floating object in the air, A program code for acquiring the aerial position information of the flying object or the floating object on which the relay station slave unit is installed, A program code for determining the shutdown of some of the multiple 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 the result of the determination to the relay station master unit, A program characterized by including the following:

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