Wireless relay device, gateway device, and communication system

Abstract

To provide a communication system capable of maintaining a FDD system communication between a base station apparatus and a terminal apparatus and reducing the weight and power consumption of a radio relay apparatus.SOLUTION: A service link and a feeder link use the same frequency band (shared frequency band) in which an FDD uplink band in which a plurality of frequency channels are adjacently arranged and an FDD downlink band in which a plurality of frequency channels are adjacently arranged are spaced apart from each other via a predetermined guard band. A radio relay apparatus includes a shared antenna, a frequency conversion unit that converts a frequency of an REV (reverse) link signal in a first frequency channel of an FDD uplink band into a frequency of a second frequency channel of an FDD downlink band, and converts a frequency of an FWD (foward) link signal in the second frequency channel of the FDD uplink band into a frequency of a first frequency channel of the FDD downlink band, and a single power amplifier that amplifies the REV link signal and the FWD link signal.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to relaying communications between a base station device and a terminal device via a wireless relay device. [Background technology]

[0002] Conventionally, there have been known radio relay devices that can stay in the sky, such as high altitude platform stations (HAPS) (also called "high altitude pseudo satellites") (see, for example, Patent Document 1). The communication line in this radio relay device is composed of a feeder link (relay radio section) between the radio relay device and a gateway (GW) device on the mobile communication network side, and a service link between the radio relay device and a terminal device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2016 / 0046387 Summary of the Invention [Problem to be solved by the invention]

[0004] In a communication system equipped with a non-regenerative radio relay device that can be used for the above-mentioned airborne radio relay device, there is a need to maintain FDD (Frequency Division Duplex) communication between a base station device on the mobile communication network side and a terminal device, while also reducing the weight and power consumption of the radio relay device. [Means for solving the problem]

[0005] A communication system according to one aspect of the present invention includes a non-regenerative wireless relay device that relays FDD (Frequency Division Duplex) communications between a base station device and a terminal device, and a gateway device connected to the base station device and capable of wireless communication with the wireless relay device. This communication system uses the same frequency band, in which an FDD uplink band in which multiple frequency channels are adjacently arranged and an FDD downlink band in which multiple frequency channels are adjacently arranged, are separated by a predetermined guard band, for a service link between the wireless relay device and the terminal device and a feeder link between the wireless relay device and the gateway device. The radio relay device includes: a shared antenna shared for transmission and reception of the service link and transmission and reception of the feeder link; a frequency conversion unit that converts the frequency of a REV (reverse) link signal in a first frequency channel of the FDD uplink band received from the terminal device via the shared antenna into the frequency of a second frequency channel of the FDD downlink band, and converts the frequency of a FWD (forward) link signal in the second frequency channel of the FDD uplink band received from the gateway device via the shared antenna into the frequency of the first frequency channel of the FDD downlink band; and a single power amplifier that amplifies the REV link signal and the FWD link signal in the FDD downlink band whose frequencies have been converted by the frequency conversion unit. The gateway device includes: a feeder link antenna used for transmitting and receiving the feeder link; a frequency conversion unit that converts the frequency of the FWD link signal in a first frequency channel of the FDD downlink band received from the base station device to the frequency of a second frequency channel of the FDD uplink band and converts the frequency of the REV link signal in the second frequency channel of the FDD downlink band received from the radio relay device via the feeder link antenna to the frequency of the first frequency channel of the FDD uplink band; a first power amplifier that amplifies the FWD link signal in the FDD uplink band whose frequency has been converted by the frequency conversion unit; and a second power amplifier that amplifies the REV link signal in the FDD uplink band whose frequency has been converted by the frequency conversion unit.

[0006] A wireless relay device according to another aspect of the present invention is a non-regenerative wireless relay device that relays FDD (Frequency Division Duplex) communications between a base station device and a terminal device. This wireless relay device uses the same frequency band, in which an FDD uplink band in which multiple frequency channels are adjacently arranged and an FDD downlink band in which multiple frequency channels are adjacently arranged, are spaced apart via a predetermined guard band, for a service link between the wireless relay device and the terminal device and a feeder link between the wireless relay device and the gateway device. The radio relay device includes: a shared antenna shared for transmission and reception of the service link and transmission and reception of the feeder link; a frequency conversion unit that converts the frequency of a REV (reverse) link signal in a first frequency channel of the FDD uplink band received from the terminal device via the shared antenna into the frequency of a second frequency channel of the FDD downlink band, and converts the frequency of a FWD (forward) link signal in the second frequency channel of the FDD uplink band received from the gateway device via the shared antenna into the frequency of the first frequency channel of the FDD downlink band; and a single power amplifier that amplifies the REV link signal and the FWD link signal in the FDD downlink band whose frequencies have been converted by the frequency conversion unit.

[0007] A gateway device according to yet another aspect of the present invention is a gateway device connected to a base station device and capable of wireless communication with a non-regenerative wireless relay device that relays FDD (Frequency Division Duplex) communications between the base station device and a terminal device. This gateway device uses the same frequency band, in which an FDD uplink band in which a plurality of frequency channels are adjacently arranged and an FDD downlink band in which a plurality of frequency channels are adjacently arranged, are spaced apart via a predetermined guard band, for a service link between the wireless relay device and the terminal device and a feeder link between the wireless relay device and the gateway device. The gateway device includes: a feeder link antenna used for transmitting and receiving the feeder link; a frequency conversion unit that converts the frequency of the FWD link signal in a first frequency channel of the FDD downlink band received from the base station device to the frequency of a second frequency channel of the FDD uplink band and converts the frequency of the REV link signal in the second frequency channel of the FDD downlink band received from the radio relay device via the feeder link antenna to the frequency of the first frequency channel of the FDD uplink band; a first power amplifier that amplifies the FWD link signal in the FDD uplink band whose frequency has been converted by the frequency conversion unit; and a second power amplifier that amplifies the REV link signal in the FDD uplink band whose frequency has been converted by the frequency conversion unit.

[0008] The radio relay device may include a single low-noise amplifier that amplifies the REV link signal and the FWD link signal in the FDD uplink band received via the shared antenna.

[0009] The frequency conversion unit of the wireless relay device may include a demodulation unit that demodulates the REV link signal and the FWD link signal in the FDD uplink band to generate a baseband signal, a baseband signal processing unit that switches the frequency channel of the REV link signal in the baseband signal from the first frequency channel to the second frequency channel and switches the frequency channel of the FWD link signal in the baseband signal from the second frequency channel to the first frequency channel, and a modulation unit that modulates a carrier wave with the baseband signals of the REV link signal and the FWD link signal whose frequency channel has been switched to generate transmission signals of the REV link signal and the FWD link signal in the FDD downlink band.

[0010] The baseband signal processing unit may include a signal branching unit that branches a baseband signal including the REV link signal and the FWD link signal demodulated by the demodulation unit into a first baseband signal and a second baseband signal; a first frequency shifting unit that extracts the FWD link signal from the first baseband signal and shifts the frequency to a lower frequency by the frequency width of a channel band; a second frequency shifting unit that extracts the REV link signal from the second baseband signal and shifts the frequency to a higher frequency by the frequency width of the channel band; and a signal combining unit that combines the first baseband signal processed by the first frequency shifting unit and the second baseband signal processed by the second frequency shifting unit.

[0011] The first frequency shift unit may include: a front-stage shift unit that shifts the frequency of the first baseband signal to a lower frequency by half the channel band so that the FWD link signal is located at a band center f0 of the baseband signal; a band-pass filter that selectively passes the FWD link signal centered at the band center f0; a gain-controlled power amplifier that amplifies the first baseband signal by controlling the gain so that transmission power to the terminal device becomes constant; and a back-stage shift unit that shifts the frequency of the first baseband signal to a lower frequency by half the channel band so that a high-frequency end of the FWD link signal is located at the band center f0. The second frequency shift unit may also include a front-stage shift unit that shifts the frequency of the second baseband signal toward higher frequencies by half the channel band so that the REV link signal is located at the band center f0 of the baseband signal, a band-pass filter that selectively passes the REV link signal centered at the band center f0, and a back-stage shift unit that shifts the frequency of the second baseband signal toward higher frequencies by half the channel band so that the low-frequency end of the REV link signal is located at the band center f0.

[0012] The radio relay device may be an airborne relay type radio relay device that is installed on the body of an aircraft or floating body located in the sky, and that forms one or more cells toward a service area on the ground or sea via the shared antenna and communicates wirelessly with one or more terminal devices located in the cell.

[0013] The program that performs at least one of the processes of frequency conversion, demodulation of the signal, switching of the frequency channel, modulation of the signal, branching of the signal, combining of the signal, shifting of the frequency, and control of the gain of the power amplifier may include a machine-learned model. [Effects of the Invention]

[0014] According to the present invention, in a non-regenerative wireless relay device that relays FDD communication between a base station device and a terminal device, it is possible to maintain FDD communication between the base station device and the terminal device while reducing the weight and power consumption of the wireless relay device. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is an explanatory diagram showing an example of the overall configuration of a communication system including an airborne radio relay device according to an embodiment. [Figure 2] Fig. 2(a) is an explanatory diagram showing an example of a repeater system using a non-regenerative wireless repeater device according to the embodiment, and Fig. 2(b) is an explanatory diagram showing an example of a base station system using a regenerative wireless repeater device according to a reference example. [Figure 3] FIG. 3 is an explanatory diagram showing a general communication system including a ground-based radio relay device according to a reference example. [Figure 4] FIG. 4 is a block diagram showing an example of the configuration of a wireless relay device in the communication system according to the reference example of FIG. [Figure 5] FIG. 5 is an explanatory diagram showing a communication system including a frequency conversion type radio relay device that uses different frequency bands for the feeder link and the service link according to another reference example. [Figure 6] FIG. 6 is an explanatory diagram showing frequency bands used in FDD wireless communication in the feeder link and the service link by the wireless relay device according to the reference example of FIG. [Figure 7] FIG. 7 is a block diagram showing an example of the configuration of the wireless relay device and the gateway device of the communication system according to the reference example of FIG. [Figure 8] FIG. 8 is an explanatory diagram illustrating an example of a communication system including a frequency conversion type radio relay device that uses the same frequency band for the feeder link and the service link according to the embodiment. [Figure 9] FIG. 9 is an explanatory diagram showing an example of the same frequency band used in FDD wireless communication in the feeder link and the service link by the wireless relay device according to the embodiment of FIG. [Figure 10] FIG. 10 is an explanatory diagram showing an example of frequency channel conversion within the same frequency band in a communication system including the wireless relay device according to the embodiment of FIG. [Figure 11] FIG. 11 is an explanatory diagram showing conversion of frequency channels in different frequency bands in a communication system including the wireless relay device according to the reference example of FIG. [Figure 12] FIG. 12 is a block diagram showing an example of the configuration of the wireless relay device and the gateway device of the communication system according to the embodiment of FIG. 8 and an example of frequency channel conversion. [Figure 13] FIG. 13 is a block diagram showing an example of the configuration of a baseband signal processing unit and an example of frequency channel conversion in the wireless relay device of the communication system according to the embodiment of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A communication system (wireless relay system) equipped with a non-regenerative wireless relay device according to the embodiment described herein uses FDD (Frequency Division Duplex) wireless relaying, in which the transmission and reception frequencies between a base station and a terminal device are different, to bundle and relay signals of a feeder link (relay wireless section) and a service link (service wireless section) onto multiple adjacent frequency channels in the same frequency band. This allows for FDD communication between the base station device and the terminal device, while also sharing the transmission circuits, reception circuits, and antennas of the feeder link and the service link, thereby reducing the weight and power consumption of the wireless relay device.

[0017] FIG. 1 is an explanatory diagram showing an example of the overall configuration of a communication system with a single cell configuration corresponding to a single base station device 80 according to an embodiment. Note that the communication system according to this embodiment may be a communication system with a multi-cell configuration in which a plurality of cells are formed. Furthermore, the communication system according to this embodiment is suitable for realizing a three-dimensional network of fourth-generation or later-generation mobile communications that supports simultaneous connection to a plurality of terminal devices (hereinafter also referred to as "UE" (user equipment)) 60, low latency, and the like. Furthermore, mobile communication standards applicable to the communication system, radio relay device, base station device, gateway device, and terminal device disclosed in this specification include fourth-generation mobile communication standards and mobile communication standards of fourth-generation or later generations.

[0018] As shown in Fig. 1, the communication system includes a high altitude platform station (HAPS) (also called a "high altitude pseudo satellite" or "stratospheric platform") 10 having an airborne radio relay device that constitutes an airborne platform. The HAPS 10 is an airborne (also called a "floating") communication platform that is located in an airspace at a predetermined altitude and forms a three-dimensional cell (three-dimensional area) 20C in a cell formation target airspace from a target service area 20A to the predetermined altitude.

[0019] HAPS10 is an air vehicle or floating body airframe 100 that is controlled autonomously or externally to float or fly in a high-altitude airspace (floating airspace) at 100 km or less above ground or sea level, and is equipped with a wireless relay device (hereinafter also referred to as a "relay communication station") 110. The airspace in which HAPS10 is located may be, for example, stratospheric airspace at an altitude of 18 km or more and 50 km or less. This airspace may also be an airspace with relatively stable weather conditions at an altitude of 15 km or more and 25 km or less, and particularly may be an airspace at an altitude of approximately 20 km.

[0020] The cell formation target airspace, which is the target airspace in which HAPS10 will form a three-dimensional cell, may be an airspace within a predetermined altitude range (for example, a range from the ground to an altitude of 1000 m or less, or an altitude range of 50 m or more and 1000 m or less) located between the airspace in which HAPS10 is located and a cell formation area near the ground covered by a base station such as a conventional macrocell base station (for example, an LTE eNodeB or a next-generation gNodeB).

[0021] The target airspace for cell formation may be above the sea, a river, or a lake. The 3D cell formed by HAPS 10 may also be formed to reach the ground or sea surface to enable communication with UE (terminal equipment) 60 located on the ground or sea.

[0022] The HAPS 10 communicates wirelessly with the UE 60 via a shared antenna 120 of a relay communication station 110 provided on an aircraft 100, such as an aircraft or floating object, located in the sky. The HAPS 10 is equipped with at least one of a battery and a solar power generation system, for example, and can fly using electric power. The HAPS 10 may be a solar plane-type HAPS as shown in the figure, or an airship-type HAPS. The HAPS 10 provided with the relay communication station 110 may be an artificial satellite (e.g., a communication satellite), a balloon, or an unmanned aerial vehicle (UAV) such as a drone or unmanned aircraft systems (UAS). The HAPS 10 may be equipped with at least one of a battery and an engine as a power source. The UAV may be, for example, an unmanned aerial vehicle that runs on fuel or a drone that runs on a battery or the like.

[0023] The relay communication station 110 includes a shared antenna (hereinafter also referred to as a "HAPS antenna") 120 shared by a service link in the service radio section and a feeder link in the relay radio section. The relay communication station 110 can communicate with the UE 60 over the service link SL via the HAPS antenna (shared antenna) 120. The HAPS antenna 120 is, for example, a beamforming-controllable array antenna that can control the direction and width of a beam that forms a cell 20C in the target service area 20A. The area through which the beam passes in the cell formation target airspace is the three-dimensional cell 20C. The multiple communication areas that the cell 20C reaches on the ground (or on the sea, etc.) are the footprint 20F.

[0024] The HAPS antenna 120 may be a beamforming controllable array antenna capable of controlling the direction and width of each of a plurality of beams that form a plurality of cells (e.g., three cells or seven cells) in the target service area 20A. Adjacent beams in the cell formation target airspace may partially overlap.

[0025] The relay communication station 110 can communicate over a feeder link FL with a HAPS gateway device (also called a "feeder station," hereinafter referred to as a "GW station") 70 installed on land (or on the sea, etc.) via a HAPS antenna 120. The HAPS antenna 120 is, for example, an array antenna whose directivity (direction of a directional beam) can be controlled.

[0026] The HAPS antenna 120 is, for example, a single or multiple array antennas in which multiple antenna elements are arranged two-dimensionally or three-dimensionally and capable of forming multiple beams toward the ground. The HAPS antenna 120 may also be a massive antenna in which multiple antenna elements are arranged two-dimensionally and capable of controlling beam directivity in the horizontal and vertical directions.

[0027] The GW station 70 can perform feeder link FL communication with the relay communication station 110 via a feeder link antenna (hereinafter also referred to as "FL antenna") 71. The FL antenna 71 is, for example, an antenna whose directivity (direction of a directional beam) can be controlled. The FL antenna 71 is, for example, a single or multiple array antennas in which multiple antenna elements are arranged two-dimensionally or three-dimensionally. The FL antenna 71 may also be a massive antenna in which many antenna elements are arranged two-dimensionally and whose directivity can be controlled in the horizontal and vertical directions.

[0028] In Fig. 1, the feeder link FL(F) and the service link SL(F) are forward links (hereinafter also referred to as "downlinks") from the GW station 70 to the UE 60 via the HAPS 10. The feeder link FL(R) and the service link SL(R) are reverse links (hereinafter also referred to as "uplinks") from the UE 60 to the GW station 70 via the HAPS 10.

[0029] UE 60 is a terminal device used by a user on land or at sea. UE 60 is, for example, a mobile phone, a smartphone, a portable personal computer with a mobile communication function, or the like, and is also called a mobile terminal, a mobile station, a mobile device, or a portable communication terminal. UE 60 may be a modular mobile station incorporated into a moving object such as a vehicle such as an automobile, or a drone, which is an aircraft such as a small remotely controlled helicopter, or may be a terminal device for an IoT (Internet of Things) device.

[0030] UE 60 can communicate with base station device 80 connected to core network 85 of the mobile communication network by FDD method via relay communication station 110 and GW station 70. UE 60 can also access external communication network 90 such as the Internet via base station device 80 and core network 85 of the mobile communication network.

[0031] In the communication system of this embodiment, FDD (Frequency Division Duplex) communication is performed in each wireless section between base station device 80 and UE (terminal device) 60. That is, the duplexing method for the downlink (forward link) and uplink (reverse link) of the service link between relay communication station 110 and UE 60, the duplexing method for the downlink (forward link) and uplink (reverse link) between base station device 80 and GW station 70, and the duplexing method for the downlink (forward link) and uplink (reverse link) between relay communication station 110 and GW station 70 are all FDD (Frequency Division Duplex).

[0032] The access method for wireless communication between the base station device 80 and the UE 60 via the relay communication station 110 and the GW station 70 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.

[0033] Furthermore, the wireless communication of the service link between relay communication station 110 and UE 60 may use MIMO (Multi-Input and Multi-Output) technology, which has functions such as diversity coding, transmit beamforming, and spatial division multiplexing (SDM) and can increase 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 UE at the same time and frequency, or MU-MIMO (Multi-User MIMO) technology, in which one base station transmits signals to multiple different UEs at the same time and frequency, or multiple different base stations transmit signals to one UE at the same time and frequency.

[0034] In the communication system configured as described above, for example, a signal from a base station device 80 is relayed by the GW station 70 and the relay communication station 110 of the HAPS 10, and communication services can be provided to UEs 60 on the ground. In particular, according to the communication system of this embodiment, the HAPS 10, which functions as an airborne platform, can provide ultra-wide area mobile communication services directly to UEs (terminal devices) 60 on the ground from the stratosphere at altitudes of 18 km or more and 50 km or less (particularly around 20 km). Furthermore, airborne platforms consisting of the HAPS 10 are attracting attention as a new form of communication suitable for use in large-scale disasters and the like.

[0035] The relay communication station (wireless relay device) 110 mounted on the airframe 100 of HAPS 10 is a non-regenerative type (hereinafter also referred to as a "repeater type") relay communication station that relays transmitted and received signals without regenerating them. Generally, wireless relay systems using the relay communication station 110 of HAPS 10 include the repeater system shown in FIG. 2(a) and the base station system shown in FIG. 2(b). In the repeater system of FIG. 2(a), the relay communication station 110 mounted on the airframe 100 of HAPS 10 is a relay station that functions as a non-regenerative repeater, and directly relays communications between the base station device 80 and the UE 60 via a bent-pipe-shaped path via the GW station 70 and the relay communication station 110. The repeater system of FIG. 2(a) is advantageous in that the base station device 80 can be installed on the ground, thereby reducing the weight and power consumption of the relay communication station (wireless relay device) 110 and facilitating multi-operator operation. On the other hand, in the base station system of Fig. 2(b), the relay communication station 110 mounted on the airframe 100 of the HAPS 10 has a base station device 80, and the base station device 80 of the relay communication station 110 is connected to a core network 85 of the mobile communication network via a backhaul line such as FWA, regenerates transmitted and received signals, and performs wireless communication with the UE 60. In the base station system of Fig. 2(b), the device configuration of the relay communication station 110 including the base station device 80 is complex, which is disadvantageous in terms of weight reduction and low power consumption, and also makes multi-operator operation difficult.

[0036] Fig. 3 is an explanatory diagram showing a general communication system including a ground-based wireless relay device 82 according to a reference example. In Fig. 3, a base station device 80 connected to a core network 85 of a mobile communication network forms a cell 20C(1) toward a target service area 20A(1) via a base station antenna 81. A wireless relay device (relay station) 82 located within the cell 20C(1) forms a cell 20C(2) toward a target service area 20A(2) located on the opposite side of the base station antenna 81, and relays wireless communication between the base station antenna 81 of the base station device 80 and a terminal device 60 within the cell 20C(2).

[0037] In the communication system of the reference example shown in FIG. 3, the same frequency (channel) is used in the service radio section (service link) and the relay radio section (feeder link). For example, in the forward link (downlink) from the base station device 80 to the UE 60, the same frequency (channel) f 1DL In the reverse link (uplink) from the UE 60 to the base station device 80, the same frequency (channel) f is used for the service radio section and the relay radio section. 1UL In this way, the same frequency (channel) f 1DL , f 1UL 3 is used when the service radio section (service link) and the relay radio section (feeder link) are spatially different. Also, the radio relay device 82 in FIG. 3 uses the same frequency (channel) f 1DL , f 1UL However, because the relay communication station 110 of the HAPS 10 flies in the sky, moves, and rotates, the service radio section and the relay radio section may spatially overlap, which may make it impossible to eliminate (or suppress) the radio interference. Therefore, it is difficult to apply a relaying method that uses the same frequency (channel) for the service radio section and the relay radio section to the relay communication station 110 of the HAPS 10.

[0038] Fig. 4 is a block diagram showing a configuration example of a radio relay device 82 in the communication system according to the reference example of Fig. 3. In Fig. 4, the radio relay device 82 includes a feeder link antenna (FL antenna) 821, a service link antenna (SL antenna) 822, duplexers 8231 and 8232, low noise amplifiers (LNAs) 8233 and 8234, power amplifiers (PAs) 8235 and 8236, and a signal processing unit 8237. A forward link (downlink) received signal received from the base station antenna 81 via the FL antenna 821 and the duplexer 8231 is amplified by the LNA 8233, processed by the signal processing unit 8237 having the functions of a digital filter and a loop interference canceller, and then amplified to a predetermined power by the PA 8235 and transmitted from the SL antenna 822 via the duplexer 8232 to the antenna 61 of the terminal device 60. In addition, the reverse link (uplink) received signal received from the antenna 61 of the terminal device 60 via the SL antenna 822 and the duplexer 8232 is amplified by the LNA 8234, processed by the signal processing unit 8237 having the functions of a digital filter and a loop interference canceller, and then amplified to a predetermined power by the PA 8236 and transmitted from the FL antenna 821 to the base station antenna 81 via the duplexer 8231.

[0039] The wireless relay device 82 in the communication system according to the reference example shown in Figures 3 and 4 requires the installation of two power amplifiers (transmitting amplifiers), which are heavy and consume a lot of power, which is disadvantageous in reducing the weight and power consumption of the wireless relay device 82.

[0040] Fig. 5 is an explanatory diagram showing a communication system including a frequency conversion type radio relay device (relay communication station) 110' that uses different frequency bands for the feeder link and the service link according to another reference example. In Fig. 5, components similar to those in Fig. 1 are given the same reference numerals, and their description will be omitted. In the communication system of the reference example in Fig. 5, different frequency bands are used for the service radio section (service link) and the relay radio section (feeder link).

[0041] For example, as shown in Fig. 6, a first frequency band 310 for the service link (e.g., 900 MHz band (Band 8)) is used in a service radio section between antenna 61 of terminal device 60 and service link antenna (SL antenna) 111 of relay communication station 110'. In first frequency band 310, there are an FDD downlink band (hereinafter also referred to as "downlink band") 311 in which a plurality of frequency channels f1, f2, and f3 of a predetermined band (e.g., 5 MHz) are adjacently arranged, and an FDD uplink band (hereinafter also referred to as "uplink band") 312 in which a plurality of frequency channels f1, f2, and f3 of a predetermined band (e.g., 5 MHz) are adjacently arranged, and they are spaced apart via a predetermined guard band. For forward link radio communication, a first frequency channel f1 of downlink band 311 of first frequency band 310 is used. 1DL is used for reverse link radio communication, and the first frequency channel f 1UL is used.

[0042] 6, a second frequency band 320 (for example, 2 GHz band (Band1)) for a feeder link different from the first frequency band 310 is used in a relay wireless section between the FL antenna 71 of the GW station 70 and the feeder link antenna (FL antenna) 112 of the relay communication station 110'. In the second frequency band 320, a downlink band (FDD downlink band) 321 in which a plurality of frequency channels f1, f2, f3, and f4 of a predetermined band (for example, 5 MHz) are adjacently arranged, and an (FDD uplink band) 322 in which a plurality of frequency channels f1, f2, f3, and f4 of a predetermined band (for example, 5 MHz) are adjacently arranged, are spaced apart via a predetermined guard band. For forward link wireless communication, a first frequency channel f 1DL is used for the reverse link radio communication, and the first frequency channel f 1UL is used.

[0043] 5 and 6, the relay communication station 110', which uses different frequency bands 310 and 320 for the service radio section (service link) and the relay radio section (feeder link), can be used even when the service radio section and the relay radio section spatially overlap. Also, since no loop interference occurs at the relay communication station 110', a loop interference canceller is not required.

[0044] Fig. 7 is a block diagram showing an example of the configuration of a relay communication station 110' and a gateway device (GW station) 70 in the communication system according to the reference example of Fig. 5. In Fig. 7, the GW station 70 includes an FL antenna 71, duplexers 701 and 702, a forward link signal path 703, and a reverse link signal path 704. The forward link signal path 703 includes a low noise amplifier (LNA) 7031, a signal processing unit 7032, and a power amplifier (PA) 7033. The reverse link signal path 704 includes a low noise amplifier (LNA) 7041, a signal processing unit 7042, and a power amplifier (PA) 7043.

[0045] In the GW station 70, a predetermined service link frequency f SL The forward link (downlink) received signal is amplified by the LNA7031 and frequency converted (f SL →f FL ) and processed by a signal processor 7032 having the function of a digital filter. FL The forward link (downlink) signal converted to is amplified by the PA 7033 to a predetermined power level and transmitted from the FL antenna 71 to the FL antenna 112 of the relay communication station 110′ via the duplexer 702. Also, a predetermined feeder link frequency f FL The received signal of the reverse link (uplink) is amplified by the LNA7041 and frequency converted (f FL →f SL ) and processed by a signal processor 7042 having the function of a digital filter.SL The reverse link (uplink) signal converted into the above signal is amplified to a predetermined power by the PA 7043 and transmitted to the base station apparatus 80 via the duplexer 701.

[0046] 7, relay communication station 110′ includes FL antenna 112, duplexers 113 and 114, forward link signal path 115, and reverse link signal path 116. Forward link signal path 115 includes low noise amplifier (LNA) 1151, signal processing unit 1152, and power amplifier (PA) 1153. Reverse link signal path 116 includes low noise amplifier (LNA) 1161, signal processing unit 1162, and power amplifier (PA) 1163.

[0047] In the relay communication station 110′, a predetermined feeder link frequency f FL The forward link (downlink) received signal is amplified by the LNA 1151 and frequency converted (f FL →f SL ) and processed by a signal processor 1152 having the function of a digital filter. SL The forward link (downlink) signal converted to is amplified to a predetermined power by the PA 1153 and transmitted from the service link antenna (also referred to as "SL antenna") 111 to the antenna 61 of the terminal device 60 via the duplexer 114. Also, a predetermined service link frequency f SL The received signal of the reverse link (uplink) is amplified by the LNA 1161 and frequency converted (f SL →f FL ) and processed by a signal processor 1162 having the function of a digital filter. FL The reverse link (uplink) signal converted into the above signal is amplified to a predetermined power by the PA 1163 and transmitted to the FL antenna 71 of the GW station 70 via the duplexer 113.

[0048] In the relay communication station (wireless relay device) 110′ in the communication system according to the reference example shown in FIGS. 5 to 7, two power amplifiers (transmitting amplifiers) which are heavy and consume a lot of power are required, which is disadvantageous in reducing the weight and power consumption of the relay communication station (wireless relay device) 110′.

[0049] Lightweight and low power consumption are important for wireless devices for airborne platforms such as HAPS and UAVs, such as the airborne relay communication station (wireless relay device) 110 (see FIG. 1) included in the communication system of this embodiment. The wireless relay system using the relay communication station 110 of this embodiment is a wireless relay system using a repeater-type relay communication station 110 for multi-operator operation, which has a simple device configuration as shown in FIG. 2(a) above. This repeater system is advantageous over the base station system of FIG. 2(b) in that it allows for lighter weight and lower power consumption of the relay communication station (wireless device) 110. Here, the majority of the power consumption in the relay communication station 110 constituting the repeater system is the transmitting amplifier (power amplifier). Furthermore, the heat dissipation mechanism of the transmitting amplifier, which is a heat source, is a heavy component. Therefore, low power consumption and light weight of the wireless circuitry, including the transmitting amplifier, are important for wireless devices for airborne platforms, such as the airborne relay communication station (wireless relay device) 110.

[0050] In this embodiment, the feeder link signal and the service link signal are bundled and relayed on adjacent channels in the same frequency band, so that a single transmission amplifier (power amplifier) ​​is shared by the feeder link and the service link in the relay communication station 110, thereby reducing the weight and power consumption of the relay communication station 110.

[0051] Fig. 8 is an explanatory diagram showing an example of a communication system including a frequency conversion type relay communication station (wireless relay device) 110 that uses the same frequency band for the feeder link and the service link according to the embodiment. Note that in Fig. 8, components similar to those in Fig. 1 above are given the same reference numerals, and their description will be omitted. In Fig. 8, the same frequency band is used for the service radio section (service link) and the relay radio section (feeder link).

[0052] For example, as shown in FIG. 9 , a frequency band (hereinafter also referred to as a “shared frequency band”) 330 (e.g., 900 MHz band (Band 8)) shared with a wireless relay section (feeder link) is used in a service wireless section (service link) between antenna 61 of terminal device 60 and HAPS antenna (shared antenna) 120 of relay communication station 110. In shared frequency band 330, an FDD downlink band (hereinafter also referred to as a “downlink band”) 331 in which a plurality of frequency channels f1, f2, and f3 of a predetermined band (e.g., 5 MHz) are adjacently arranged, and an FDD uplink band 332 in which a plurality of frequency channels f1, f2, and f3 of a predetermined band (e.g., 5 MHz) are adjacently arranged, are spaced apart via a predetermined guard band. For forward link wireless communication, a second frequency channel f1 of FDD uplink band 332 in shared frequency band 330 is used. 2UL (feeder link) and the first frequency channel f of the FDD downlink band 331 1DL For reverse link wireless communication, the first frequency channel f of the FDD uplink band 332 in the shared frequency band 330 is used. 1UL (service link) and the second frequency channel f of the FDD downlink band 331 2DL (feeder link) is used.

[0053] 10 is an explanatory diagram showing an example of frequency channel conversion within the same frequency band (shared frequency band) 330 in a communication system including a relay communication station (wireless relay device) 110 according to the embodiment of FIG. 8. In FIG. 10, in the case of forward link wireless communication, a base station device 80 converts a first frequency channel f 1DL The GW station 70 transmits a forward link signal (hereinafter also referred to as "FWD link signal") SL(F) of the service link to the GW station (gateway device) 70 via the first frequency channel f 1DL 2nd frequency channel f of the uplink band 3322UL The GW station 70 converts the frequency-converted signal into a second frequency channel f 2UL The relay communication station 110 transmits the frequency of the FWD link signal FL(F) of the feeder link received from the GW station 70 to the second frequency channel f 2UL 1st frequency channel f of downstream band 331 1DL The relay communication station 110 converts the frequency-converted signal into the first frequency channel f of the downlink band 331 as the FWD link signal SL(F) of the service link. 1DL The terminal device 60 transmits the signal to the terminal device 60 via the first frequency channel f 1DL The FWD link signal SL(F) of the service link is received from the relay communication station 110 via the FWD link signal SL(F).

[0054] On the other hand, in FIG. 10, in the case of reverse link wireless communication, the terminal device 60 transmits the first frequency channel f 1UL The relay communication station 110 transmits a reverse link signal (hereinafter also referred to as "REV link signal") SL(R) of the service link to the relay communication station 110 via the first frequency channel f 1DL to the second frequency channel f of the downstream band 331 2DL The relay communication station 110 converts the frequency-converted signal into a second frequency channel f of the downlink band 331 as a reverse link signal (REV link signal) FL(R) of the feeder link. 2DL The GW station 70 transmits the frequency of the REV link signal FL(R) of the feeder link received from the relay communication station 110 to the second frequency channel f 2DL 1st frequency channel f of the uplink band 332 1ULThe GW station 70 converts the frequency-converted signal into the first frequency channel f 1UL The base station device 80 transmits the signal to the base station device 80 via the first frequency channel f 1UL The REV link signal SL(R) of the service link is received from the GW station 70 via the .

[0055] 10, the relay communication station 110 transmits a forward link signal SL(F) of the service link and a reverse link signal FL(R) of the feeder link over a plurality of first frequency channels f adjacent to each other in a downstream band 331 of a shared frequency band 330. 1DL and the second frequency channel f 2DL Therefore, in the relay communication station 110 of this embodiment, the power amplifier (transmission amplifier) ​​of the transmission circuit and the antenna 120 can be shared for the forward link and the service link.

[0056] In addition, in the relay communication station 110 of this embodiment, the service link signal SL(R) of the reverse link and the feeder link signal FL(F) of the forward link are transmitted over a plurality of first frequency channels f adjacent to each other in the up-band 332 of the shared frequency band 330. 1UL and the second frequency channel f 2UL Therefore, in the wireless relay device 110 of this embodiment, the low noise amplifier (LNA) of the receiving circuit can be shared between the forward link and the service link.

[0057] Fig. 11 is an explanatory diagram showing conversion of frequency channels in different frequency bands 310, 320 in a communication system including a relay communication station (wireless relay device) 110' according to the reference example of Fig. 5. In Fig. 11, components similar to those in Fig. 10 are denoted by the same reference numerals, and their description will be omitted.

[0058] In the reference example of FIG. 11, in the case of wireless communication of the forward link, the GW station 70 sets the frequency of the FWD link signal SL(F) of the service link received from the base station device 80 to the first frequency channel f 1DL , the first frequency channel f of the downlink band 321 of the second frequency band 320. 1DL The GW station 70 converts the frequency-converted signal into a first frequency channel f of the downstream band 321 of the second frequency band 320 as a FWD link signal FL(F) of the feeder link. 1DL The relay communication station 110' transmits the frequency of the FWD link signal FL(F) of the feeder link received from the GW station 70 to the first frequency channel f 1DL , the first frequency channel f of the downlink band 311 of the first frequency band 310. 1DL The relay communication station 110′ converts the frequency-converted signal into the first frequency channel f of the downlink band 311 of the first frequency band 310 as the FWD link signal SL(F) of the service link. 1DL The data is transmitted to the terminal device 60 via the

[0059] On the other hand, in FIG. 11, in the case of reverse link wireless communication, the relay communication station 110′ changes the frequency of the REV link signal SL(R) of the service link received from the terminal device 60 to the first frequency channel f 1UL , the first frequency channel f of the uplink band 322 of the second frequency band 320. 1UL The relay communication station 110' converts the frequency-converted signal into the first frequency channel f of the upstream band 322 of the second frequency band 320 as the REV link signal FL(R) of the feeder link. 1UL The GW station 70 transmits the frequency of the REV link signal FL(R) of the feeder link received from the relay communication station 110′ to the first frequency channel f 1UL , the first frequency channel f of the uplink band 312 of the first frequency band 310. 1ULThe GW station 70 converts the frequency-converted signal into the first frequency channel f in the uplink band 312 of the first frequency band 310 as the REV link signal SL(R) of the service link. 1UL The signal is transmitted to the base station device 80 via the

[0060] In the reference example of FIG. 11, the relay communication station 110′ transmits the FWD link signal SL(F) of the service link to the first frequency channel f 1DL and transmits the REV link signal FL(R) of the feeder link in the first frequency channel f of the upstream band 322 of the second frequency band 320 different from the first frequency band 310. 1UL Therefore, in the relay communication station 110' of the reference example, it is not possible to share the power amplifier (transmission amplifier) ​​of the transmission circuit for the forward link and the service link.

[0061] The relay communication station 110′ also transmits the REV link signal SL(R) of the service link to the first frequency channel f 1UL and amplifying the feeder link FWD signal FL(F) into a first frequency channel f in a downstream band 321 of a second frequency band 320 different from the first frequency band 310. 1DL Therefore, in the relay communication station 110' of the reference example, it is not possible to share a low noise amplifier (LNA) in the receiving circuit between the forward link and the service link.

[0062] 12 is a block diagram showing an example of the configuration of the relay communication station (wireless relay device) 110 and the gateway device (GW station) 70 of the communication system according to the embodiment of FIG. 8, and an example of frequency channel conversion. SL1 indicates the frequency of a signal transmitted and received between the base station device 80 and the terminal device 60 via the GW station 70 and the relay communication station 110 (hereinafter also referred to as the "first service link frequency"). SL2indicates the frequency of a signal in the shared frequency band 330 transmitted and received between the GW station 70 and the relay communication station 110 (hereinafter also referred to as the "second service link frequency"). In FIG. 12, the first service link frequency f SL1 is the frequency f of the first frequency channel f1 of each of the downlink band 311 and the uplink band 312 of the first frequency band 310 for the service link. 1DL ,f 1UL , and the frequency f of the first frequency channel f1 of each of the downlink band 331 and the uplink band 332 of the shared frequency band 330. 1DL ,f 1UL In addition, the second service link frequency f SL2 is the frequency f of the second frequency channel f2 of each of the downlink band 331 and the uplink band 332 of the shared frequency band 330. 2DL ,f 2UL The first frequency band 310 for the service link and the shared frequency band 330 are the same frequency band (for example, the 900 MHz band (Band 8)).

[0063] 12, the GW station 70 includes an FL antenna 71, duplexers 701 and 702, a forward link signal path 703, and a reverse link signal path 704. The forward link signal path 703 includes a low noise amplifier (LNA) 7031, a signal processing unit 7032, and a power amplifier (PA) 7033. The reverse link signal path 704 includes a low noise amplifier (LNA) 7041, a signal processing unit 7042, and a power amplifier (PA) 7043.

[0064] In the GW station 70, the first service link frequency f SL1 (In the illustrated example, the first frequency channel f 1DL ) FWD link (downlink) signal is amplified by LNA7031 and frequency converted (f 1DL →f 2UL ) and processed by a signal processor 7032 having the functions of a digital filter. SL2(In the illustrated example, the second frequency channel f 2UL ) is amplified to a predetermined power by the PA 7033 and transmitted from the FL antenna 71 to the HAPS antenna 120 of the relay communication station 110 via the duplexer 702.

[0065] The frequency f for the second service link received from the HAPS antenna 120 of the relay communication station 110 via the FL antenna 71 and the duplexer 702 SL2 (In the illustrated example, the second frequency channel f 2DL The REV link (uplink) signal of 2DL →f 1UL ) and processed by a signal processor 7042 having the function of a digital filter. SL1 (In the illustrated example, the first frequency channel f 1UL The REV link (uplink) signal converted to the REV link (uplink) signal is amplified to a predetermined power by the PA 7043 and transmitted to the base station device 80 via the duplexer 701.

[0066] 12, the relay communication station 110 includes a single HAPS antenna (shared antenna) 120 as an FL&SL common antenna used in common for the feeder link (FL) and the service link (SL), a single duplexer 113, an FL&SL common receiving circuit having a single low noise amplifier (LNA) 117, a signal processing unit 118, and an FL&SL common transmitting circuit having a single power amplifier (PA) 119. The signal processing unit 118 performs frequency conversion (f 2UL →f 1DL ,f 1UL →f 2DL ) and a frequency conversion unit that has the function of a digital filter.

[0067] In the relay communication station 110, the second service link frequency f SL2 (In the illustrated example, the second frequency channel f 2UL ) forward link (downlink) received signal is amplified by LNA 117 and frequency converted (f 2UL →f 1DL ) and processed by a signal processor 118 having the function of a digital filter. SL1 (In the illustrated example, the first frequency channel f 1DL The forward link (downlink) signal converted into the FM signal is amplified to a predetermined power by the PA 119 and transmitted from the HAPS antenna 120 to the antenna 61 of the terminal device 60 via the duplexer 113.

[0068] The first service link frequency f received from the antenna 61 of the terminal device 60 via the HAPS antenna 120 and the duplexer 113 SL1 (In the illustrated example, the first frequency channel f 1UL The received signal of the reverse link (uplink) of 1UL →f 2DL ) and processed by a signal processor 118 having the function of a digital filter. SL2 (In the illustrated example, the second frequency channel f 2DL The reverse link (uplink) signal converted into the FM signal is amplified to a predetermined power by the PA 119 and transmitted to the FL antenna 71 of the GW station 70 via the duplexer 113.

[0069] According to the relay communication station (wireless relay device) 110 of Fig. 12, adjacent frequency channels f2 and f1 in the same frequency band (shared frequency band) 330 are used for the feeder link transmission signal (REV link signal) and the service link transmission signal (FWD link signal), so that the feeder link REV link signal and the service link FWD link signal of the relay communication station 110 can be amplified by a single power amplifier (transmission amplifier) ​​119. Therefore, the relay communication station 110 can achieve a reduction in weight and power consumption by using only one power amplifier (transmission amplifier), instead of the two conventionally used. Furthermore, according to the relay communication station 110 of Fig. 12, signal processing that was performed separately for the service link and feeder link frequency bands 310 and 320 in conventional frequency conversion type wireless relay devices (see Figs. 5 to 7) can be performed in a common circuit, thereby achieving a reduction in the weight of the signal processing unit circuit.

[0070] 12, the signal processing unit 118 having a function as a frequency conversion unit provided in the relay communication station 110 may have a demodulation unit, a baseband signal processing unit, and a modulation unit. The demodulation unit demodulates the REV link signal and the FWD link signal in the FDD uplink band 332 of the shared frequency band 330 to generate a baseband signal (digital signal) of an intermediate frequency. The baseband signal processing unit converts the frequency channel of the REV link signal in the baseband signal generated by the demodulation unit into a first frequency channel f 1UL to the second frequency channel f 2DL In addition, the baseband signal processing unit switches the frequency channel of the FWD link signal in the baseband signal generated by the demodulation unit to the second frequency channel f 2UL to the first frequency channel f 1DL The modulation unit modulates a high frequency carrier wave with the baseband signals of the REV link signal and FWD link signal whose frequency channel has been switched, and generates transmission signals of the REV link signal and FWD link signal in the FDD downlink band 311 of the first frequency band 310.

[0071] Fig. 13 is a block diagram showing an example of the configuration of the baseband signal processing unit 1100 of the signal processing unit 118 in the relay communication station (wireless relay device) 110 of the communication system according to the embodiment of Fig. 8, and an example of frequency channel conversion. Fig. 13 also shows the relationship between the FWD link signals 400(FL)-405(FL) and the REV link signals 400(RL)-405(RL) at multiple main points A-E in the baseband signal processing unit 1100 and the frequency channels CH1 and CH2 in the baseband frequency domain. In the figure, B is the bandwidth (channel band) of the frequency channels CH1 and CH2, and f0 is the center frequency of the baseband signal.

[0072] 13, a baseband signal processing unit 1100 includes a signal branching unit 1110, a first frequency shifting unit (forward link PassA) 1120, a second frequency shifting unit (reverse link PassB) 1130, and a signal combining unit 1140. The signal branching unit 1110 branches a baseband signal (input digital signal) including a REV link signal 400 (RL) from the terminal device 60 and a FWD link signal from the GW station 70, demodulated by the demodulation unit, into two signals: a first baseband signal in PassA for the forward link to the first frequency shifting unit 1120, and a second baseband signal in PassB for the reverse link to the second frequency shifting unit 1130. The first frequency shifting unit 1120 extracts the FWD link signal from the first baseband signal and shifts the frequency to a lower frequency by the frequency width B of the channel band. The second frequency shifter 1130 extracts the REV link signal from the second baseband signal and shifts the frequency to the higher frequency side by the frequency width B of the channel band. The signal combiner 1140 combines the first baseband signal processed by the first frequency shifter (PassA) 1120 and the second baseband signal processed by the second frequency shifter (PassB) 1130 and outputs the combined signal. The FWD link signal 405 (FL) in the combined baseband signal is transmitted to the terminal device 60, and the REV link signal 405 (RL) is transmitted to the GW station 70.

[0073] The first frequency shifter 1120 includes a pre-shifter 1121, a band-pass filter (BPF) 1122, a gain-controlled power amplifier 1123, and a post-shifter 1124. The pre-shifter 1121 shifts the frequency of the first baseband signal to a lower frequency by half the channel band B so that the FWD link signal 401 (FL) is located at the band center f0 of the first baseband signal. The band-pass filter (BPF) 1122 has a predetermined band-pass frequency characteristic 451 and selectively passes the FWD link signal 401 (FL) centered at the band center f0. The gain-controlled power amplifier 1123 amplifies the first baseband signal by gain control based on a predetermined control signal (e.g., a synchronization signal in the 5G or LTE mobile communication standard) so that the transmission power to the terminal device 60 is constant. The post-shift unit 1124 shifts the frequency of the first baseband signal to the lower frequency side by half the channel band B so that the high-frequency end of the FWD link signal 403 (FL) is located at the band center f0. The FWD link signal 403 (FL) is a signal received from the GW station 70 and transmitted to the terminal device 60.

[0074] The second frequency shifter 1130 includes a pre-shifter 1131, a bandpass filter (BPF) 1132, and a post-shifter 1133. The pre-shifter 1131 shifts the frequency of the second baseband signal toward the higher frequency side by half the channel band B so that the REV link signal 402(RL) is located at the band center f0 of the second baseband signal. The bandpass filter (BPF) 1132 has a predetermined bandpass frequency characteristic 452 and selectively passes the REV link signal 402(RL) centered at the band center f0. The post-shifter 1133 shifts the frequency of the second baseband signal toward the higher frequency side by half the channel band B so that the low frequency end of the REV link signal 404(RL) is located at the band center f0. The REV link signal 404(RL) is a signal received from the terminal device 60 and transmitted to the GW station 70.

[0075] As described above, according to this embodiment, it is possible to maintain FDD communication between the base station device 80 and the terminal device 60 on the mobile communication network side, and in the relay communication station (wireless relay device) 110, the FWD link signal SL(F) of the service link and the REV link signal FL(R) of the feeder link can be amplified by a single power amplifier (transmitting amplifier) ​​119 and transmitted collectively, thereby making it possible to reduce the weight and power consumption of the relay communication station 110.

[0076] Furthermore, according to this embodiment, the relay communication station (wireless relay device) 110 can simultaneously receive the REV link signal SL(R) of the service link and the FWD link signal FL(F) of the feeder link and amplify them using a single low-noise power amplifier (receiving amplifier) ​​117, thereby further reducing the weight and power consumption of the relay communication station 110.

[0077] Furthermore, according to this embodiment, the base station device 80 and the terminal device 60 can each transmit and receive service link signals in the same manner as in normal FDD communication, so that FDD communication can be maintained in the base station device 80 and the terminal device 60 without changing the wireless communication configuration of each of the base station device 80 and the terminal device 60.

[0078] The present invention can maintain FDD communications in base station equipment and terminal equipment on the mobile communications network side while reducing the weight and power consumption of wireless relay equipment, thereby contributing to the achievement of Goal 9 of the Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation."

[0079] It should be noted that the process steps and components of the wireless relay device and communication system 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.

[0080] With regard to hardware implementation, means such as processing units used to realize the above steps and components in an entity (e.g., various wireless communication devices, base stations, base station equipment, gateway equipment, wireless relay equipment, terminal equipment, various nodes of a network, hard disk drive equipment, or optical disk drive equipment) 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 in this specification, computers, or combinations thereof.

[0081] Furthermore, with regard to firmware and / or software implementations, the means, such as a processing unit, used to realize the above components may be implemented with a program (e.g., code, such as procedures, functions, modules, instructions, etc.) that performs the functions described herein. In general, any computer / processor-readable medium tangibly embodying firmware and / or software code may be used to implement the means, such as a processing unit, used to realize the above steps and components described herein. For example, the firmware and / or software code may be stored in a memory and executed by a computer or processor, such as in a controller. The memory may be implemented within the computer or processor or external to the processor. Furthermore, 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 programmable read-only memory (EEPROM), flash memory, floppy disk, compact disk (CD), digital versatile disk (DVD), magnetic or optical data storage device, etc. The code may be executed by one or more computers or processors and may cause the computers or processors to perform certain aspects of the functionality described herein.

[0082] The medium may be a non-transitory recording medium. The program code may be in any format as long as it can be read and executed by a computer, processor, or other device or machine. For example, the program code may be in any of source code, object code, and binary code, or may be a mixture of two or more of these codes.

[0083] 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]

[0084] 20A: Service area 20C: Cell 20F: Footprint 60: Terminal device 61: Antenna 70: GW station (gateway device) 71:FL Antenna 80:Base station equipment 85: Core Network 90:Communication Network 100: Aircraft 110: Relay communication station (radio relay device) 111:SL Antenna 112:FL Antenna 113: Duplexer 117: Low noise amplifier (LNA) 118: Signal processing section 119: Power amplifier (PA) 120: HAPS antenna (shared antenna) 310: First frequency band 330: Shared frequency band 701: Duplexer 702: Duplexer 703: Forward link signal path 704: Reverse link signal path 1100: Baseband signal processing section 1110: Signal branching section 1120: First frequency shift unit 1121: Front shift section 1122: Bandpass filter (BPF) 1123: Power amplifier 1124: Rear shift section 1130: Second frequency shift unit 1131: Front shift section 1132: Bandpass filter (BPF) 1133: Rear shift section 1140: Signal synthesis unit 7031: Low noise amplifier (LNA) 7032: Signal processing section 7033: Power Amplifier (PA) 7041: Low noise amplifier (LNA) 7042: Signal processing section 7043: Power Amplifier (PA)

Claims

1. 1. A communication system comprising: A non-regenerative wireless relay device that relays communication between a base station device and a terminal device using an FDD (Frequency Division Duplex) system, and a gateway device that is connected to the base station device and is capable of wireless communication with the wireless relay device, A service link between the wireless relay device and the terminal device and a feeder link between the wireless relay device and the gateway device use the same frequency band in which an FDD uplink band in which a plurality of frequency channels are adjacently arranged and an FDD downlink band in which a plurality of frequency channels are adjacently arranged are spaced apart via a predetermined guard band, The wireless relay device a shared antenna used for transmitting and receiving signals on the service link and for transmitting and receiving signals on the feeder link; a frequency conversion unit that converts the frequency of a REV (reverse) link signal in a first frequency channel of the FDD uplink band received from the terminal device via the shared antenna into the frequency of a second frequency channel of the FDD downlink band, and converts the frequency of an FWD (forward) link signal in the second frequency channel of the FDD uplink band received from the gateway device via the shared antenna into the frequency of the first frequency channel of the FDD downlink band; a single power amplifier that amplifies the REV link signal and the FWD link signal in the FDD downlink band whose frequency has been converted by the frequency conversion unit; The gateway device a feeder link antenna used for transmitting and receiving signals from the feeder link; a frequency conversion unit that converts the frequency of the FWD link signal in a first frequency channel of the FDD downlink band received from the base station device to the frequency of a second frequency channel of the FDD uplink band, and converts the frequency of the REV link signal in the second frequency channel of the FDD downlink band received from the radio relay device via the feeder link antenna to the frequency of the first frequency channel of the FDD uplink band; a first power amplifier for amplifying the FWD link signal in the FDD uplink band whose frequency has been converted by the frequency conversion unit; a second power amplifier for amplifying the REV link signal in the FDD uplink band whose frequency has been converted by the frequency conversion unit; A communication system comprising:

2. 2. The communication system of claim 1, the radio relay device includes a single low-noise amplifier that amplifies the REV link signal and the FWD link signal in the FDD uplink band received via the shared antenna; A communication system comprising:

3. 2. The communication system of claim 1, The frequency conversion unit of the wireless relay device a demodulation unit that demodulates the REV link signal and the FWD link signal in the FDD uplink band to generate a baseband signal; a baseband signal processing unit that switches the frequency channel of the REV link signal in the baseband signal from the first frequency channel to the second frequency channel and switches the frequency channel of the FWD link signal in the baseband signal from the second frequency channel to the first frequency channel; a modulation unit that modulates a carrier wave with baseband signals of the REV link signal and the FWD link signal whose frequency channel has been switched to generate transmission signals of the REV link signal and the FWD link signal in the FDD downlink band; A communication system comprising:

4. 4. The communication system of claim 3, The baseband signal processing unit includes: a signal branching unit that branches a baseband signal including the REV link signal and the FWD link signal demodulated by the demodulation unit into a first baseband signal and a second baseband signal; a first frequency shifter that extracts the FWD link signal from the first baseband signal and shifts the frequency of the FWD link signal to a lower frequency by a frequency width of a channel band; a second frequency shifter that extracts the REV link signal from the second baseband signal and shifts the frequency of the REV link signal to a higher frequency side by a frequency width of a channel band; a signal combining unit that combines the first baseband signal processed by the first frequency shift unit and the second baseband signal processed by the second frequency shift unit; A communication system comprising:

5. 5. The communication system of claim 4, The first frequency shift unit a front-stage shifter that shifts the frequency of the first baseband signal to a lower frequency by half the channel band so that the FWD link signal is positioned at a band center f0 of the baseband signal; a bandpass filter that selectively passes the FWD link signal centered on the band center f0; a gain-controlled power amplifier that amplifies the first baseband signal by controlling the gain so that the transmission power to the terminal device is constant; a post-shift unit that shifts the frequency of the first baseband signal by half the channel band toward a lower frequency side so that a high-frequency end of the FWD link signal is located at the band center f0, The second frequency shift unit a front-stage shift unit that shifts the frequency of the second baseband signal by half the channel band toward a higher frequency side so that the REV link signal is positioned at a band center f0 of the baseband signal; a band-pass filter that selectively passes the REV link signal around the band center f0; a post-shift unit that shifts the frequency of the second baseband signal by half the channel band toward a higher frequency side so that a low frequency end of the REV link signal is located at the band center f0. A communication system comprising:

6. 6. The communication system according to claim 1, A communication system characterized in that the radio relay device is an airborne relay type radio relay device that is installed on the body of an aircraft or floating body located in the sky, forms one or more cells toward a service area on the ground or sea via the shared antenna, and communicates wirelessly with one or more terminal devices located in the cell.

7. A non-regenerative wireless relay device that relays FDD (Frequency Division Duplex) communications between a base station device and a terminal device, A service link between the wireless relay device and the terminal device and a feeder link between the wireless relay device and the gateway device use the same frequency band in which an FDD uplink band in which a plurality of frequency channels are adjacently arranged and an FDD downlink band in which a plurality of frequency channels are adjacently arranged are spaced apart via a predetermined guard band, a shared antenna used for transmitting and receiving signals on the service link and for transmitting and receiving signals on the feeder link; a frequency conversion unit that converts the frequency of a REV (reverse) link signal in a first frequency channel of the FDD uplink band received from the terminal device via the shared antenna into the frequency of a second frequency channel of the FDD downlink band, and converts the frequency of an FWD (forward) link signal in the second frequency channel of the FDD uplink band received from the gateway device via the shared antenna into the frequency of the first frequency channel of the FDD downlink band; a single power amplifier for amplifying the REV link signal and the FWD link signal in the FDD downlink band whose frequency has been converted by the frequency conversion unit; A wireless relay device comprising:

8. 8. The wireless relay device according to claim 7, a single low-noise amplifier for amplifying the REV link signal and the FWD link signal in the FDD uplink band received via the shared antenna; A wireless relay device characterized by:

9. 8. The wireless relay device according to claim 7, The frequency conversion unit a demodulation unit that demodulates the REV link signal and the FWD link signal in the FDD uplink band to generate a baseband signal; a baseband signal processing unit that switches the frequency channel of the REV link signal in the baseband signal from the first frequency channel to the second frequency channel and switches the frequency channel of the FWD link signal in the baseband signal from the second frequency channel to the first frequency channel; a modulation unit that modulates a carrier wave with baseband signals of the REV link signal and the FWD link signal whose frequency channel has been switched to generate transmission signals of the REV link signal and the FWD link signal in the FDD downlink band; A wireless relay device comprising:

10. 10. The wireless relay device according to claim 9, The baseband signal processing unit includes: a signal branching unit that branches a baseband signal including the REV link signal and the FWD link signal demodulated by the demodulation unit into a first baseband signal and a second baseband signal; a first frequency shifter that extracts the FWD link signal from the first baseband signal and shifts the frequency of the FWD link signal to a lower frequency by a frequency width of a channel band; a second frequency shifter that extracts the REV link signal from the second baseband signal and shifts the frequency of the REV link signal to a higher frequency side by a frequency width of a channel band; a signal combining unit that combines the first baseband signal processed by the first frequency shift unit and the second baseband signal processed by the second frequency shift unit; A wireless relay device comprising:

11. 11. The wireless relay device according to claim 10, The first frequency shift unit a front-stage shifter that shifts the frequency of the first baseband signal to a lower frequency by half the channel band so that the FWD link signal is positioned at a band center f0 of the baseband signal; a bandpass filter that selectively passes the FWD link signal centered on the band center f0; a gain-controlled power amplifier that amplifies the first baseband signal by controlling the gain so that the transmission power to the terminal device is constant; a post-shift unit that shifts the frequency of the first baseband signal by half the channel band toward a lower frequency side so that a high-frequency end of the FWD link signal is located at the band center f0, The second frequency shift unit a front-stage shift unit that shifts the frequency of the second baseband signal by half the channel band toward a higher frequency side so that the REV link signal is positioned at a band center f0 of the baseband signal; a band-pass filter that selectively passes the REV link signal around the band center f0; a post-shift unit that shifts the frequency of the second baseband signal by half the channel band toward a higher frequency side so that a low frequency end of the REV link signal is located at the band center f0. A wireless relay device characterized by:

12. 12. The radio relay device according to claim 7, The radio relay device is an airborne relay type radio relay device that is installed on the body of an aircraft or floating body located in the sky, forms one or more cells toward a service area on the ground or sea via the shared antenna, and wirelessly communicates with one or more terminal devices located in the cell. A wireless relay device characterized by:

13. A gateway device connected to a base station device and capable of wireless communication with a non-regenerative wireless relay device that relays communication between the base station device and a terminal device using an FDD (Frequency Division Duplex) method, A service link between the wireless relay device and the terminal device and a feeder link between the wireless relay device and the gateway device use the same frequency band in which an FDD uplink band in which a plurality of frequency channels are adjacently arranged and an FDD downlink band in which a plurality of frequency channels are adjacently arranged are spaced apart via a predetermined guard band, a feeder link antenna used for transmitting and receiving signals from the feeder link; a frequency conversion unit that converts the frequency of the FWD link signal in a first frequency channel of the FDD downlink band received from the base station device to the frequency of a second frequency channel of the FDD uplink band, and converts the frequency of the REV link signal in the second frequency channel of the FDD downlink band received from the radio relay device via the feeder link antenna to the frequency of the first frequency channel of the FDD uplink band; a first power amplifier for amplifying the FWD link signal in the FDD uplink band whose frequency has been converted by the frequency conversion unit; a second power amplifier that amplifies the REV link signal in the FDD uplink band whose frequency has been converted by the frequency conversion unit; A gateway device characterized by:

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