Wireless relay device, gateway device, and communication system

Abstract

This invention provides a communication system capable of maintaining FDD communication in a base station device and a terminal device, and reducing the impact of phase noise in a relay radio section between a radio relay device and a gateway device. The radio relay device includes a means for converting an FDD signal transmitted and received in a radio section of a service link between the radio relay device and the terminal device, and a TDD signal transmitted and received in a relay radio section between the radio relay device and the gateway device. The gateway device includes a means for converting an FDD signal transmitted / received to / from the base station device, and a TDD signal transmitted / received in the relay radio section between the gateway device and the radio relay device. The radio relay device and the gateway device transmit / receive radio signals in the TDD scheme in the relay radio section.

Description

Wireless relay device, gateway device and communication system

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

[0002] Conventionally, there has been known a radio relay device that can stay in the sky, such as a high altitude platform station (HAPS) (also called a "high altitude pseudo satellite") (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.

[0003] US Patent Application Publication No. 2016 / 0046387

[0004] In a non-regenerative wireless repeater that can be used for the above-mentioned airborne wireless repeater, etc., there is a problem in that it is desired to maintain FDD (Frequency Division Duplex) communication between a base station device on the mobile communication network side and a terminal device, while reducing the influence of phase noise in the relay wireless section between the wireless repeater that relays that communication and a gateway device.

[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. The wireless relay device has means for converting between the FDD signals transmitted and received in a wireless section of a service link between the terminal device and the wireless relay device and a TDD (Time Division Duplex) signal transmitted and received in a relay wireless section between the wireless relay device and the gateway device. The gateway device has means for converting between the FDD signals transmitted and received with the base station device and the TDD signals transmitted and received in the relay wireless section between the wireless relay device and the gateway device. The wireless relay device and the gateway device transmit and receive wireless signals in the TDD system in the relay wireless section.

[0006] In the communication system, the frequency band of the TDD radio signal and the frequency band of the FDD radio signal may be different from each other.

[0007] In the communication system, the frequency band of the TDD radio signal may be a millimeter wave frequency band of 20 GHz or more and 300 GHz or less, and the frequency band of the FDD radio signal may be the frequency band of 10 GHz or less.

[0008] In the communication system, the wireless relay device may include a forward link communication unit and a reverse link communication unit. The forward link communication unit of the wireless relay device may include a frequency conversion unit that converts the frequency of a forward link signal in the frequency band of the TDD system received from the gateway device to a frequency of the FDD system, a signal sampling unit that samples the signal converted by the frequency conversion unit, and a time signal expansion unit that expands the signal sampled by the signal sampling unit by N times on a time axis. The reverse link communication unit of the wireless relay device may include a reverse link communication unit that includes a signal sampling unit that samples a reverse link signal in the frequency band of the FDD system received from the terminal device, a time signal compression unit that compresses the signal sampled by the signal sampling unit to 1 / N on the time axis, and a frequency conversion unit that converts the frequency of the signal compressed by the time signal compression unit to a frequency of the TDD system. The gateway device may also include a forward link communication unit and a reverse link communication unit. The forward link communication unit of the gateway device includes a signal sampling unit that samples a forward link signal in the frequency band of the FDD system received from the base station device, a time signal compression unit that compresses the signal sampled by the signal sampling unit to 1 / N on the time axis, and a frequency conversion unit that converts the frequency of the signal compressed by the time signal compression unit to the frequency of the TDD system.The reverse link communication unit of the gateway device includes a frequency conversion unit that converts the frequency of a reverse link signal in the frequency band of the TDD system received from the wireless relay device to the frequency of the FDD system, a signal sampling unit that samples the signal converted by the frequency conversion unit, and a time signal expansion unit that expands the signal sampled by the signal sampling unit by N times on the time axis.

[0009] In the communication system, known signals and control data used to control the wireless relay device and known signals and control data used to control the gateway device may be placed in a guard time between a communication band time of a forward link and a communication band time of a reverse link that are alternately repeated in the relay wireless section.

[0010] In the communication system, 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 a service link antenna and communicates wirelessly with one or more terminal devices located in the cell.

[0011] In the communication system, the gateway device may be provided with a plurality of connection units corresponding to a plurality of base station devices, and the radio relay device may form a plurality of cells using the same frequency corresponding to the plurality of base station devices in a service link, and may time-multiplex radio signals corresponding to the plurality of cells in the relay radio section in a feeder link.

[0012] 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, the wireless relay device comprising: means for converting between an FDD signal transmitted and received in a wireless section of a service link between the terminal device and the FDD signal and a TDD (Time Division Duplex) signal transmitted and received in a relay wireless section between the base station device and a gateway device connected to the base station device; and the wireless relay device transmits and receives TDD radio signals in the relay wireless section between the gateway device and the FDD signal.

[0013] In the radio relay device, the frequency band of the TDD radio signal and the frequency band of the FDD radio signal may be different from each other.

[0014] In the radio relay device, the frequency band of the TDD radio signal may be a millimeter wave frequency band of 20 GHz or more and 300 GHz or less, and the frequency band of the FDD radio signal may be the frequency band of 10 GHz or less.

[0015] The wireless relay device may include a forward link communication unit and a reverse link communication unit. The forward link communication unit may include a frequency conversion unit that converts the frequency of a forward link signal in the frequency band of the TDD system received from the gateway device to a frequency of the FDD system, a signal sampling unit that samples the signal converted by the frequency conversion unit, and a time signal expansion unit that expands the signal sampled by the signal sampling unit by N times on a time axis. The reverse link communication unit may include a signal sampling unit that samples a reverse link signal in the frequency band of the FDD system received from the terminal device, a time signal compression unit that compresses the signal sampled by the signal sampling unit to 1 / N on the time axis, and a frequency conversion unit that converts the frequency of the signal compressed by the time signal compression unit to a frequency of the TDD system.

[0016] In the wireless relay device, known signals and control data used to control the wireless relay device and known signals and control data used to control the gateway device may be placed in a guard time between a communication band time of a forward link and a communication band time of a reverse link that are alternately repeated in the relay wireless section.

[0017] 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 forms one or more cells toward a service area on the ground or sea via a service link antenna, and communicates wirelessly with one or more terminal devices located in the cell.

[0018] The radio relay device may form multiple cells using the same frequency corresponding to multiple base station devices in the service link, and may time-multiplex radio signals corresponding to the multiple cells in the relay radio section in the feeder link.

[0019] According to yet another aspect of the present invention, there is provided 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, the gateway device having means for converting between FDD signals transmitted to and received from the base station device and TDD (Time Division Duplex) signals transmitted to and received in a relay wireless section between the gateway device and the wireless relay device, and transmitting and receiving wireless signals in the TDD system in the relay wireless section between the gateway device and the wireless relay device.

[0020] In the gateway device, the frequency band of the TDD radio signal and the frequency band of the FDD radio signal may be different from each other.

[0021] In the gateway device, the frequency band of the TDD radio signal may be a millimeter wave frequency band of 20 GHz or more and 300 GHz or less, and the frequency band of the FDD radio signal may be the frequency band of 10 GHz or less.

[0022] The gateway device may include a forward link communication unit and a reverse link communication unit. The forward link communication unit may include a signal sampling unit that samples a forward link signal in the frequency band of the FDD system received from the base station device, a time signal compression unit that compresses the signal sampled by the signal sampling unit to 1 / N on the time axis, and a frequency conversion unit that converts the frequency of the signal compressed by the time signal compression unit to the frequency of the TDD system. The reverse link communication unit may include a frequency conversion unit that converts the frequency of a reverse link signal in the frequency band of the TDD system received from the wireless relay device to the frequency of the FDD system, a signal sampling unit that samples the signal converted by the frequency conversion unit, and a time signal expansion unit that expands the signal sampled by the signal sampling unit by N times on the time axis.

[0023] In the gateway device, known signals and control data used to control the wireless relay device and known signals and control data used to control the gateway device may be arranged in a guard time between a communication band time of a forward link and a communication band time of a reverse link that are alternately repeated in the relay wireless section.

[0024] The program that performs at least one of the processes of converting the frequency, sampling the signal, expanding the signal, and compressing the signal may include a machine-learned model.

[0025] According to the present invention, in a non-regenerative wireless relay device that relays communications 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 influence of phase noise in the relay wireless section between the wireless relay device and a gateway device.

[0026] 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 according to an embodiment. FIG. 2A is an explanatory diagram showing an example of a repeater system using a non-regenerative wireless relay device according to an embodiment. FIG. 2B is an explanatory diagram showing an example of a base station system using a regenerative wireless relay device according to a reference example. FIG. 3A is an explanatory diagram showing an example of frequency bands used in a service link and a feeder link (relay wireless section) in a communication system according to an embodiment. FIG. 3B is a spectral diagram showing an example of an arrangement on the frequency axis of subcarriers on which OFDM signals are transmitted in the Sub6 band and the millimeter wave band. FIG. 3C is an explanatory diagram showing an example of phase noise of a Sub6 band signal and a millimeter wave band signal. FIG. 4A is an explanatory diagram showing an example of a communication band of an FDD system in a base station device and a terminal device in a communication system according to an embodiment. FIG. 4B is an explanatory diagram showing an example of a time domain waveform of a signal in the FDD system. FIG. 4C is a spectral diagram showing an example of an arrangement on the frequency axis of subcarriers on which OFDM signals are transmitted in the FDD system. Fig. 5A is an explanatory diagram showing an example of a TDD communication band in a feeder link (relay radio section) of a communication system according to an embodiment. Fig. 5B is an explanatory diagram showing an example of a time-domain waveform of a signal in the TDD system. Fig. 5C is a spectrum diagram showing an example of an arrangement on a frequency axis of subcarriers on which OFDM signals are transmitted in the TDD system. Fig. 6 is a block diagram showing an example of a configuration of main parts of a gateway device and a radio relay device in a single-cell communication system according to an embodiment. Fig. 7 is an explanatory diagram showing an example of the overall configuration of a multi-cell communication system corresponding to multiple base station devices according to an embodiment. Fig. 8 is an explanatory diagram showing an example of time changes in the communication bands of the FDD downlink (forward link) and uplink (reverse link) in the multiple base station devices, the TDD downlink and uplink in the feeder link (relay radio section), and the FDD communication bands in the service link in the communication system of Fig. 7.Fig. 9 is an explanatory diagram showing an example of time changes in the communication bands of the FDD downlink (forward link) and uplink (reverse link) of a plurality of base station devices, the FDD downlink and uplink of a feeder link (relay wireless section), and the FDD communication band of a service link in a communication system according to a reference example. Fig. 10 is a block diagram showing an example of the configuration of the main parts of a gateway device and a wireless relay device in a multi-cell communication system according to an embodiment. Fig. 11 is an explanatory diagram showing an example of timing detection and level measurement of an SSB signal used for AGC in a wireless relay device. Fig. 12 is an explanatory diagram showing an example of a control known signal arranged in a guard time between the communication band time of the TDD downlink (forward link) and the communication band time of the uplink (reverse link) of a feeder link (relay wireless section) in the communication system according to an embodiment. FIG. 13 is an explanatory diagram showing an example of an AGC pilot signal and supervisory control data arranged in a guard time between a communication band time of a downlink (forward link) and a communication band time of an uplink (reverse link) in a TDD system of a feeder link (relay wireless section) in a communication system according to an embodiment.

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A communication system according to the embodiment described herein includes a wireless relay device that converts a relay wireless section (feeder link) between a base station and a terminal device in an FDD (Frequency Division Duplex) wireless relay system, in which the transmission frequency and the reception frequency are different from each other, to a TDD (Time Division Duplex) wireless relay system.

[0028] 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 is suitable for realizing a three-dimensional network of fourth-generation or later-generation mobile communications that supports simultaneous connection to multiple terminal devices (hereinafter also referred to as "UEs" (user devices)) 60, low latency, etc. 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 fourth-generation or later-generation mobile communication standards.

[0029] 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 or levitating communication platform that is located in an airspace at a predetermined altitude and forms a three-dimensional cell (three-dimensional area) in a cell formation target airspace at the predetermined altitude toward a target service area 20A.

[0030] HAPS 10 is an aircraft or floating body 100 that is controlled by autonomous control or external control to float or fly in a high-altitude airspace (floating airspace) 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 HAPS 10 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.

[0031] The cell formation target airspace, which is the target airspace in which a three-dimensional cell is formed by HAPS10, may be an airspace within a predetermined altitude range (e.g., 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 (e.g., an LTE eNodeB or a next-generation gNodeB).

[0032] The cell formation target airspace may be above the sea, a river, or a lake. The three-dimensional cell formed by HAPS 10 may also be formed to reach the ground or sea surface so as to enable communication with UE (terminal equipment) 60 located on the ground or sea.

[0033] The HAPS 10 wirelessly communicates with the UE 60 via a service link antenna (also referred to as an "SL antenna") 111 of a relay communication station 110 provided on an airframe 100, such as an aircraft or floating object, located in the sky. The HAPS 10 may be equipped with at least one of a battery and a solar power generation system and 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 a UAS (Unmanned Aircraft Systems). The HAPS 10 may also be equipped with at least one of a battery and an engine as a power source for flight. The UAV may be, for example, an unmanned aircraft that runs on fuel, or a drone that runs on batteries, etc.

[0034] The relay communication station 110 includes a service link antenna (SL antenna) 111 and a feeder link antenna (hereinafter also referred to as an "FL antenna") 112. The relay communication station 110 can perform service link SL communication with the UE 60 via the SL antenna 111. The SL antenna 111 is, for example, a beamforming-controllable array antenna that can control the direction and width of a beam that forms a cell 20C in a 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 over the sea, etc.) are the footprint 20F.

[0035] The SL antenna 111 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 each other.

[0036] The SL antenna 111 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 SL antenna 111 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.

[0037] The relay communication station 110 can communicate over the feeder link FL with a gateway device (also called a "feeder station"; hereinafter referred to as a "GW station") 70 for HAPS installed on land (or sea, etc.) via the FL antenna 112. The FL antenna 112 is, for example, an array antenna whose directivity (direction of a directional beam) can be controlled. The FL antenna 112 is, for example, a single or multiple array antennas in which multiple antenna elements are arranged two-dimensionally or three-dimensionally. The FL antenna 112 may also be a massive antenna in which multiple antenna elements are arranged two-dimensionally and whose directivity can be controlled in the horizontal and vertical directions.

[0038] 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 multiple antenna elements are arranged two-dimensionally and whose directivity can be controlled in the horizontal and vertical directions.

[0039] 1 , a feeder link FL(F) and a 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. A feeder link FL(R) and a 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.

[0040] UE 60 is a terminal device used by a user on land or sea. UE 60 is, for example, a mobile phone, a smartphone, a portable personal computer with mobile communication capabilities, etc., 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.

[0041] 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.

[0042] In the communication system of this embodiment, communication is performed between the base station device 80 and the UE (terminal device) 60 using the FDD (Frequency Division Duplex) method. Therefore, the duplexing method for the downlink (forward link) and uplink (reverse link) of the service link between the relay communication station 110 and the UE 60 is the FDD (Frequency Division Duplex) method. The duplexing method for the downlink (forward link) and uplink (reverse link) between the base station device 80 and the GW station 70 is also the FDD (Frequency Division Duplex) method. On the other hand, the duplexing method for the downlink (forward link) and uplink (reverse link) between the relay communication station 110 and the GW station 70 is the TDD (Time Division Duplex) method.

[0043] The relay communication station 110 and the GW station 70 have a function of converting the duplexing method because they need to relay communications using different duplexing methods. For example, the relay communication station 110 has a means for converting between an FDD signal transmitted and received in the wireless section of the service link with the UE 60 and a TDD signal transmitted and received in the relay wireless section of the feeder link with the GW station 70. The GW station 70 also has a means for converting between an FDD signal transmitted and received with the base station device 80 and a TDD signal transmitted and received in the relay wireless section of the feeder link with the relay communication station 110. This allows the relay communication station 110 and the GW station 70 to transmit and receive radio signals in the TDD method in the relay wireless section of the feeder link.

[0044] 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.

[0045] In addition, 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 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 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.

[0046] 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 functioning 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 about 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.

[0047] The relay communication station (wireless relay device) 110 mounted on the airframe 100 of the 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 the HAPS 10 include the repeater system shown in Fig. 2A and the base station system shown in Fig. 2B. In the repeater system of Fig. 2A, the relay communication station 110 mounted on the airframe 100 of the 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. In the base station system of Fig. 2B , a relay communication station 110 mounted on an airframe 100 of 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 a mobile communication network via a backhaul line such as an FWA, and regenerates transmitted and received signals to perform wireless communication with UE 60. In the base station system of Fig. 2B , the device configuration of the relay communication station is complex, and multi-operator operation is difficult.

[0048] The communication system of this embodiment uses a repeater system that uses a repeater-type relay communication station 110 for multi-operator operation, which has a simple device configuration. Furthermore, as described above, the repeater system of this embodiment uses the TDD method as the duplex method in the relay wireless section of the feeder link between the relay communication station 110 and the GW station 70. Furthermore, in the communication system of this embodiment, the frequency band of the TDD wireless signal in the relay wireless section of the feeder link is a millimeter wave frequency of 20 GHz or more and 300 GHz or less.

[0049] 3A is an explanatory diagram showing an example of frequency bands used in a service link SL and a feeder link (relay wireless section) FL in a communication system according to an embodiment. The frequency band of a TDD radio signal in the feeder link and the frequency band of an FDD radio signal in the service link are different frequency bands. In the illustrated example, the uplink frequency band F of the FDD radio signal in the service link SL is ＳＬ u and downlink frequency band F ＳＬd is a frequency band of 10 GHz or less (for example, low band, mid band, or Sub6 band). Here, the low band is a frequency band of 3.5 GHz or less (for example, 900 MHz band), and the mid band is a frequency band higher than 3.5 GHz and lower than 6 GHz (for example, 3.7 GHz band, 4.5 GHz band). The low band and mid band are collectively referred to as the Sub6 band. Furthermore, the frequency band of the TDD radio signal of the feeder link FL is a millimeter wave frequency band of 20 GHz or more and 300 GHz or less (for example, 28 GHz band, 31 GHz band, 38 GHz band, 39 GHz band).

[0050] Figure 3B is a spectrum diagram showing an example of the arrangement of subcarriers on the frequency axis for transmitting OFDM signals in the Sub6 band and the millimeter wave band. Figure 3C is an explanatory diagram showing an example of the phase noise of a Sub6 band signal and a millimeter wave band signal. As shown in Figure 3B, when an OFDM signal is transmitted in the Sub6 band, the spacing (SCS) of subcarriers 902 is, for example, 15 kHz. On the other hand, when an OFDM signal is transmitted in the millimeter wave band, the spacing (SCS) of subcarriers 901 is, for example, 60 kHz, which can be wider than the spacing of subcarriers 902 in the Sub6 band. As shown in Figure 3C, the phase noise when transmitting an OFDM signal varies depending on the frequency band. In Figure 3C, f0 is the center frequency of the central subcarrier in the Sub6 band. 3C, the spectrum of phase noise N2 of the narrowband signal in the Sub6 band and the spectrum of phase noise N1 of the narrowband signal in the millimeter-wave band are also displayed, for convenience, aligned with the center frequency of the center subcarrier in the Sub6 band. The phase noise N2 of the center subcarrier in the Sub6 band is sufficiently small at the center frequencies of the adjacent subcarriers on both sides (f0+SCS, f0-SCS). On the other hand, the phase noise N1 of the center subcarrier in the millimeter-wave band is large even at the center frequencies of the adjacent subcarriers on both sides of the Sub6 band (f0+SCS, f0-SCS) (Sub6 band phase noise N2+ΔN).

[0051] In this embodiment, in order to reduce the influence of phase noise between adjacent subcarriers in the millimeter wave band in the feed link, the subcarrier spacing (SCS) is set to several times (e.g., 4 times, 8 times, or 16 times) the subcarrier spacing (SCS) for the Sub6 band. For example, the subcarrier spacing (SCS) for the millimeter wave band in the feed link is set to 120 kHz, which is eight times the subcarrier spacing (SCS) of 15 kHz for the Sub6 band. By widening the subcarrier spacing (SCS) for the millimeter wave band in the feed link in this manner, it is possible to improve resistance to phase noise when using high-frequency millimeter waves. In particular, in the communication system of this embodiment, the duplexing method for the feed link is TDD, and therefore the entire allocated frequency band can be used in both the downlink (forward link) and the uplink (reverse link), and therefore there are fewer restrictions on setting the subcarrier spacing (SCS) large.

[0052] 4A is an explanatory diagram showing an example of a communication band of the FDD system in a base station device 80 and a UE (terminal device) 60 of a communication system according to an embodiment. In the FDD system, a downlink (forward link) communication band 912 (DL) and an uplink (reverse link) communication band 912 (UL) are set to different frequency bands. FIG. 4B is an explanatory diagram showing an example of a time-domain waveform 922 of a signal in the FDD system, and FIG. 4C is a spectral diagram showing an example of an arrangement on the frequency axis of subcarriers on which OFDM signals are transmitted in the FDD system. The subcarrier spacing SCS shown in the figure is 15 kHz in the case of a low band (e.g., Sub6 band).

[0053] 5A is an explanatory diagram showing an example of a TDD communication band in a feeder link (relay wireless section) of a communication system according to an embodiment. In the illustrated TDD feeder link, a communication band 911 (UL) of an uplink (reverse link) and a communication band 911 (DL) of a downlink (forward link) of the feeder link (relay wireless section) are repeatedly arranged at a predetermined period on the time axis. A guard time 931 of a predetermined time (e.g., 1 / 24 millisecond) is provided between the uplink communication band 911 (UL) and the downlink communication band 911 (DL) to prevent mutual interference. The subcarrier spacing SCS of each of the uplink and downlink in the feeder link (relay wireless section) of the TDD method is N times (e.g., 4 times, 8 times, or 16 times) the SCS in the FDD method. For example, the SCS of the millimeter wave band in Fig. 5C is 120 kHz, which is eight times the SCS (= 15 kHz) of the low-band FDD system in Fig. 4C described above. In this case, the time domain waveform 921 of the TDD system signal (see Fig. 5B) is a waveform obtained by compressing the time domain waveform 922 of the FDD system signal described above to one-eighth on the time axis.

[0054] 6 is a block diagram showing an example of the configuration of the main parts of a gateway device (GW station) 70 and a wireless relay device (relay communication station) 110 in a communication system with a single cell configuration according to an embodiment. The gateway device (GW station) 70 also functions as a parent device for wireless communication of the feeder link, and the wireless relay device (relay communication station) 110 also functions as a child device for wireless communication of the feeder link.

[0055] 6 , the wireless relay device (relay communication station) 110 includes a forward link communication unit 113 and a reverse link communication unit 114. The forward link communication unit 113 includes a frequency conversion unit 1131 that converts the frequency of a forward link signal in the frequency band of the TDD system received from the gateway device (GW station) 70 into a frequency of the FDD system, a signal sampling unit 1132 that samples the signal converted by the frequency conversion unit 1131, and a time signal expansion unit 1133 that expands the signal sampled by the signal sampling unit 1132 by N times on the time axis. Here, “N” is a value obtained by dividing the subcarrier spacing (SCS) in the TDD system by the subcarrier spacing (SCS) in the FDD system.

[0056] The reverse link communication unit 114 has a signal sampling unit 1141 that samples a reverse link signal in the frequency band of the FDD system received from the terminal device (UE) 60, a time signal compression unit 1142 that compresses the signal sampled by the signal sampling unit 1141 to 1 / N on the time axis, and a frequency conversion unit 1143 that converts the frequency of the signal compressed by the time signal compression unit 1142 to a frequency of the TDD system.

[0057] The gateway device (GW station) 70 includes a forward link communication unit 701 and a reverse link communication unit 702. The forward link communication unit 701 includes a signal sampling unit 7011 that samples a forward link signal in the frequency band of the FDD system received from the base station device 80, a time signal compression unit 7012 that compresses the signal sampled by the signal sampling unit 7011 to 1 / N on the time axis, and a frequency conversion unit 7013 that converts the frequency of the signal compressed by the time signal compression unit 7012 into a frequency of the TDD system.

[0058] The reverse link communication unit 702 has a frequency conversion unit 7021 that converts the frequency of a reverse link signal in the frequency band of the TDD system received from the wireless relay device (relay communication station) 110 into a frequency of the FDD system, a signal sampling unit 7022 that samples the signal after conversion by the frequency conversion unit 7021, and a time signal expansion unit 7023 that expands the signal sampled by the signal sampling unit 7022 by N times on the time axis.

[0059] As described above, according to the embodiment shown in FIGS. 1 to 6, in a communication system with a single cell configuration corresponding to a single base station device 80, it is possible to reduce the influence of phase noise in the relay wireless section of the feeder link between the wireless relay device (relay communication station) 110 and the gateway device (GW station) 70 while maintaining FDD communication between the base station device 80 and the terminal device (UE) 60.

[0060] 7 is an explanatory diagram showing an example of the overall configuration of a communication system having a multi-cell configuration corresponding to a plurality of base station devices 80(1) to 80(3) according to the embodiment. Note that in FIG. 7, components similar to those in FIG. 1 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0061] 7, relay communication station 110 forms multiple cells 20C(1) to 20C(3) in target service area 20A via SL antenna 111. Multiple communication areas where multiple cells 20C(1) to 20C(3) reach the ground (or sea, etc.) are footprints 20F(1) to 20F(3). Note that the illustrated example shows a case where three cells 20C(1) to 20C(3) are formed via SL antenna 111, but the number of cells 20C may be two, four or more.

[0062] The GW station 70 is connected to a plurality of base station devices 80(1) to 80(3), which respectively correspond to a plurality of cells 20C(1) to 20C(3). The plurality of base station devices 80(1) to 80(3) are connected to a core network 85 of the mobile communication network of the telecommunications carrier. UEs 60 located in the plurality of cells 20C(1) to 20C(3) can communicate with the base station devices 80(1) to 80(3) connected to the core network 85 of the mobile communication network via the relay communication station 110 and the GW station 70 using the FDD method.

[0063] Figure 8 is an explanatory diagram showing an example of time changes in the communication bands of the FDD downlink (forward link) and uplink (reverse link) in the multiple base station devices 80(1) to 80(3) in the communication system of Figure 7, the communication bands of the TDD downlink and uplink in the feeder link (relay radio section) and the FDD communication band in the service link. In the FDD method before cell multiplexing in Figure 8, in each of the multiple base station devices 80(1) to 80(3), the communication bands 912(1)(DL) to 912(3)(DL) that are the same frequency band in the downlink (forward link) and the communication bands 912(1)(UL) to 912(3)(UL) that are the same frequency band in the uplink (reverse link) are set to different frequency bands.

[0064] In the relay radio section of the feeder link between the GW station (gateway device) 70 and the relay communication station (radio relay device) 110, signals transmitted and received over the feeder link for each of the multiple base station devices 80(1) to 80(3) are combined using a TDD cell multiplexing method, and the downlink (forward link) and uplink (reverse link) between the relay communication station 110 and the GW station 70 are multiplexed. In the illustrated feeder link TDD method, the uplink (reverse link) communication band 911 (UL) and the downlink (forward link) communication band 911 (DL) of the feeder link (relay radio section) are repeatedly arranged at a predetermined period on the time axis in the order of the base station devices 80(1), 80(2), and 80(3). A guard time of a predetermined time (e.g., 1 / 24 millisecond) is provided between the uplink communication band 911 (UL) and the downlink communication band 911 (DL) to prevent mutual interference.

[0065] In the service link between the relay communication station (wireless relay device) 110 and UE 60 residing in each of the plurality of cells 20C(1) to 20C(3), downlink (forward link) and uplink (reverse link) signals multiplexed by the TDD cell multiplexing method are separated, and the downlink (forward link) communication bands 913(1)(DL) to 913(3)(DL) and the uplink (reverse link) communication bands 913(1)(UL) to 913(3)(UL) are set to different frequency bands. In addition, since the beams directed from the relay communication station (wireless relay device) 110 to the multiple cells 20C(1) to 20C(3) are in different directions, the downlink (forward link) communication bands 913(1)(DL) to 913(3)(DL) of the same frequency band are multiplexed by spatial multiplexing, and the uplink (reverse link) communication bands 913(1)(UL) to 913(3)(UL) of the same frequency band are multiplexed.

[0066] 9 is an explanatory diagram showing an example of time changes in the communication bands of the FDD downlink (forward link) and uplink (reverse link) of a plurality of base station devices, the FDD downlink and uplink of the feeder link (relay wireless section), and the FDD communication band of the service link in a communication system according to a reference example. In the reference example of FIG. 9, in the relay wireless section of the feeder link between a GW station (gateway device) 70 and a relay communication station (wireless relay device) 110, signals transmitted and received over the feeder link for each of a plurality of base station devices 80(1) to 80(3) are multiplexed by an FDD cell multiplexing method, and the downlinks (forward links) 914(1)(DL) to 914(3)(DL) and uplinks (reverse links) 914(1)(UL) to 914(3)(UL) between the relay communication station 110 and the GW station 70 are all multiplexed so that they are distributed and arranged at different frequencies.

[0067] 10 is a block diagram showing an example of the main configuration of a gateway device (GW station) 70 and a wireless relay device (relay communication station) 110 in a communication system having a multiple-cell configuration according to an embodiment. Note that in FIG. 10, components similar to those in FIG. 6 are denoted by the same reference numerals, and descriptions thereof will be omitted. Also, in FIG. 10, multiple terminal devices (UE) 60(1) to 60(3) are terminal devices located in multiple cells 20C(1) to 20C(3), respectively, and multiple base station devices 80(1) to 80(3) are base station devices that form multiple cells 20C(1) to 20C(3), respectively.

[0068] 10 , the wireless relay device (relay communication station) 110 includes a forward link communication unit 113 and a reverse link communication unit 114. The forward link communication unit 113 includes a frequency conversion unit 1131 that converts the frequency of a forward link signal in a TDD frequency band received from the gateway device (GW station) 70 into a frequency of an FDD system, a signal sampling unit 1132 that samples the signal converted by the frequency conversion unit 1131, and a time signal separation unit 1134 that separates the signal sampled by the signal sampling unit 1132 into signals on a time axis for each cell. Furthermore, the forward link communication unit 113 includes a plurality of time signal expansion units 1133(1) to 1133(3) that expand the signals for each cell separated by the time signal separation unit 1134 by N times on the time axis, and a plurality of time adjustment units 1135(1) to 1135(3) that adjust the time on the time axis of the signals expanded by the plurality of time signal expansion units. The multiple time adjustment units 1135(1) to 1135(3) are time-synchronized with one another.

[0069] The reverse link communication unit 114 includes a plurality of signal sampling units 1141(1) to 1141(3) that sample reverse link signals in the FDD frequency band received from a plurality of terminal devices (UE) 60(1) to 60(3) that are respectively present in a plurality of cells 20C(1) to 20C(3), a plurality of time signal compression units 1142(1) to 1142(3) that compress the signals sampled by the plurality of signal sampling units 1141(1) to 1141(3) to 1 / N on the time axis, and a plurality of time adjustment units 1144(1) to 1144(3) that adjust the time on the time axis of the signals compressed by the plurality of time signal compression units. The plurality of time adjustment units 1144(1) to 1144(3) are time-synchronized with each other. Furthermore, the reverse link communication unit 114 has a time signal synthesis unit 1145 that synthesizes, on the time axis, signals from multiple terminal devices (UE) 60(1) to 60(3) for each UE of each cell that have been time-adjusted by multiple time adjustment units, and a frequency conversion unit 1143 that converts the frequency of the signal synthesized by the time signal synthesis unit 1145 into a frequency of the TDD system.

[0070] The gateway device (GW station) 70 includes a forward link communication unit 701 and a reverse link communication unit 702. The forward link communication unit 701 includes a plurality of signal sampling units 7011(1) to 7011(3) that sample forward link signals in the FDD frequency band received from a plurality of base station devices 80(1) to 80(3), a plurality of time signal compression units 7012(1) to 7012(3) that compress the signals sampled by the plurality of signal sampling units to 1 / N on the time axis, and a plurality of time adjustment units 7014(1) to 7014(3) that adjust the time on the time axis of the signals compressed by the plurality of time signal compression units. The plurality of time adjustment units 7014(1) to 7014(3) are time-synchronized with each other. Furthermore, the forward link communication unit 701 has a time signal synthesis unit 7015 that synthesizes, on the time axis, signals from a plurality of base station devices 80(1) to 80(3) that have been time-adjusted by a plurality of time adjustment units, and a frequency conversion unit 7013 that converts the frequency of the signal synthesized by the time signal synthesis unit 7015 into a frequency for the TDD system.

[0071] The reverse link communication unit 702 includes a frequency conversion unit 7021 that converts the frequency of a reverse link signal in the TDD frequency band received from the wireless relay device (relay communication station) 110 into a frequency of the FDD system, a signal sampling unit 7022 that samples the signal converted by the frequency conversion unit 7021, and a time signal separation unit 7024 that separates the signal sampled by the signal sampling unit 7022 into signals on the time axis for each base station device (each cell). Furthermore, the reverse link communication unit 702 includes multiple time signal expansion units 7023(1) to 7023(3) that expand the signals for each base station device (each cell) separated by the time signal separation unit 7024 by N times on the time axis, and multiple time adjustment units 7025(1) to 7025(3) that adjust the time on the time axis of the signals expanded by the multiple time signal expansion units. The multiple time adjustment units 7025(1) to 7025(3) are time-synchronized with each other.

[0072] As described above, according to the embodiments shown in FIGS. 7 to 10, in a communication system having a multiple-cell configuration corresponding to a plurality of base station devices 80(1) to 80(3), it is possible to reduce the influence of phase noise in the relay wireless section of the feeder link between the wireless relay device (relay communication station) 110 and the gateway device (GW station) 70 while maintaining FDD communication in the terminal devices (UE) 60(1) to 60(3) located in the plurality of base station devices 80(1) to 80(3) and the plurality of cells 20C(1) to 20C(3).

[0073] In the communication system of this embodiment, known signals and control data used for controlling the wireless relay device (relay communication station) 110 (e.g., amplifier gain control) and known signals and control data used for controlling the gateway device (GW station) 70 (e.g., amplifier gain control) may be placed in the guard time between the communication band time of the forward link and the communication band time of the reverse link, which are alternately repeated in the relay wireless section of the feeder link.

[0074] 11 is an explanatory diagram showing an example of timing detection and level measurement of an SSB (synchronization signal block) signal used for AGC (automatic gain control) of an amplifier in a wireless relay device (relay communication station) 110. The AGC (automatic gain control) of the amplifier in the wireless relay device (relay communication station) 110 can be performed based on the reception result of the SSB (synchronization signal block) as a control block including synchronization signals (PSS, SSS) that are known signals in a wireless frame.

[0075] The SSBs include synchronization signals PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal), as well as a PBCH (Physical Broadcast Channel) to which broadcast information for UE 60 is assigned, and are arranged in slot units or resource block units of a radio frame. For example, as shown in FIG. 11 , an SS burst set consisting of five slots (T1 = 5 ms) with a predetermined subcarrier width is defined in a radio frame, and SSBs are arranged in any number of slots from the beginning of the SS burst set. In the example of FIG. 11 , two sets of SSBs are arranged in each of the first two slots. The SS burst set is repeatedly transmitted within the cell at a predetermined SS burst set period (T2 = 5 ms to 160 ms, initial value: 20 ms). Each of the multiple SSBs in the SS burst set is transmitted by multiple beams oriented in different directions within the cell.

[0076] 11 , timing detection and level measurement of a PSS (Primary Synchronization Signal), which is a known signal included in an SSB received from a base station device 80 via a gateway station 70, can be performed, for example, by calculating a correlation value between the PSS replica and the received signal while sliding the PSS replica, and then based on the peak position and level of the time change in the calculation result of the correlation value. The amplifier of the radio relay device (relay communication station) 110 can control the gain based on the result of the level measurement of the PSS (Primary Synchronization Signal) so that the power of the transmission signal of the service link SL to the terminal device (UE) 60 is constant.

[0077] 12 is an explanatory diagram showing an example of a control known signal arranged in a guard time between a communication bandwidth time of a downlink (forward link) and a communication bandwidth time of an uplink (reverse link) in a TDD scheme of a feeder link (relay wireless section) in a communication system according to an embodiment. In FIG. 12 , a control known signal (e.g., a pilot signal or a reference signal) is arranged in guard times 931 (DL) and 931 (UL) between a downlink communication bandwidth time 911 (DL) and an uplink communication bandwidth time 911 (UL). For example, a gateway device (GW station) 70 transmits a known signal (DL) in the guard time 931 (DL) preceding the downlink communication bandwidth time 911 (DL), and a wireless relay device (relay communication station) 110 controls the gain of a receiving amplifier of the feeder link or a transmitting amplifier of the service link based on a reception result of the known signal (DL). Further, for example, the wireless relay device (relay communication station) 110 transmits a known signal (UL) in a guard time 931 (UL) preceding the uplink communication band 911 time (UL), and the gateway device (GW station) 70 controls the gain of the receiving amplifier of the feeder link based on the reception result of the known signal (UL).

[0078] 13 is an explanatory diagram showing an example of an AGC pilot signal and supervisory control data as known signals arranged in a guard time between a communication bandwidth time 911 (DL) of a downlink (forward link) and a communication bandwidth time 911 (UL) of an uplink (reverse link) in a TDD scheme of a feeder link (relay wireless section) in a communication system according to an embodiment. In FIG. 13, the AGC control pilot signal and supervisory control data are arranged in the guard time between the downlink communication bandwidth time 911 (DL) and the uplink communication bandwidth time 911 (UL). For example, the wireless relay device (relay communication station) 110 transmits an AGC control pilot signal Sp (UL) in the guard time preceding the first uplink communication bandwidth time 911 (UL), and transmits supervisory control data Dmc (UL) in the guard time preceding the second and third uplink communication bandwidth times 911 (UL). The gateway device (GW station) 70 controls the gain of the receiving amplifier of the feeder link based on the reception results of the AGC control pilot signal Sp(UL) and the supervisory control data Dmc(UL). For example, the gateway device (GW station) 70 transmits the AGC control pilot signal Sp(DL) in a guard time preceding the communication band time 911(DL) of the first downlink, and transmits the supervisory control data Dmc(DL) in the guard times preceding the communication band times 911(DL) of the second and third downlinks. The wireless relay device (relay communication station) 110 controls the gain of the receiving amplifier of the feeder link or the transmitting amplifier of the service link based on the reception results of the AGC control pilot signal Sp(DL) and the supervisory control data Dmc(DL).

[0079] As shown in Fig. 13, by transmitting and receiving an AGC pilot signal and supervisory control data during the guard time in a TDD feeder link (relay wireless section), AGC independent of the relay wireless system can be realized. Also, in the uplink (reverse link) from the wireless relay device (relay communication station) 110 to the gateway device (GW station) 70, the gain of the feeder link receiving amplifier in the gateway device (GW station) 70 can be controlled. Furthermore, because supervisory control data can be transmitted and received using the guard time between the communication band time 911 (DL) of the downlink (forward link) and the communication band time 911 (UL) of the uplink (reverse link), external relay lines can be reduced.

[0080] As described above, according to this embodiment, it is possible to reduce the influence of phase noise in the relay wireless section of the feeder link between the wireless relay device and the gateway device while maintaining FDD communication between the base station device and the terminal device.

[0081] Furthermore, according to the present embodiment, the TDD scheme is used in the relay radio section of the feeder link, and therefore the same frequency can be used for the downlink (forward link) and the uplink (reverse link). This makes it possible to reduce the guard band that would be required if the FDD scheme were used in the feeder link.

[0082] Furthermore, according to this embodiment, known signals and control data used for controlling radio equipment for the downlink and uplink (for example, automatic gain control of the receiver of a radio relay device, automatic gain control of the receiver of a gateway device, etc.) can be placed in the guard time between the communication band time of the downlink (forward link) and the communication band time of the uplink (reverse link) that are alternately repeated in the relay radio section of the TDD feeder link. Therefore, even if the propagation path characteristics of the TDD feeder link change when communication between a base station device and a terminal device is relayed, it is possible to prevent degradation of communication quality due to the change in the propagation path characteristics of the feeder link.

[0083] The present invention can reduce the effects of phase noise in the relay wireless section between the wireless relay device and the gateway device while maintaining FDD communication between the base station device and the terminal device, 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 promote innovation and resilience."

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

[0085] Regarding 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 devices, gateway devices, wireless relay devices, terminal devices, various nodes of a network, hard disk drive devices, or optical disk drive devices) may be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic units designed to perform the functions described in this specification, computers, or combinations thereof.

[0086] 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 control device. The memory may be implemented within the computer or processor, or external to the processor. The firmware and / or software code may also be stored on a computer or processor readable medium such as, for example, random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), flash memory, floppy disk, compact disk (CD), digital versatile disk (DVD), magnetic or optical data storage device, etc. The code may be executed by one or more computers or processors and may cause the computers or processors to perform certain aspects of the functionality described herein.

[0087] The medium may be a non-transitory recording medium. The program code may be in any format as long as it can be read and executed by a computer, processor, or other device or machine. For example, the program code may be in any of source code, object code, and binary code, or may be a mixture of two or more of these codes.

[0088] Moreover, the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0089] 10: HAPS 20A: Service area 20C: Cell 20F: Footprint 70: GW station (gateway device) 71: FL antenna 80: Base station device 85: Core network 100: Aircraft 110: Relay communication station (radio relay device) 111: SL antenna 112: FL antenna 113: Forward link communication unit 114: Reverse link communication unit 701: Forward link communication unit 702: Reverse link communication unit

Claims

1. A communications system comprising 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 that is connected to the base station device and capable of wireless communications with the wireless relay device, wherein the wireless relay device has means for converting between the FDD signals transmitted and received in the wireless section of the service link between the terminal device and the TDD (Time Division Duplex) signals transmitted and received in the relay wireless section between the gateway device, and the gateway device has means for converting between the FDD signals transmitted and received with the base station device and the TDD signals transmitted and received in the relay wireless section between the wireless relay device, and wherein the wireless relay device and the gateway device transmit and receive wireless signals in the TDD system in the relay wireless section.

2. A communication system according to claim 1, wherein the frequency band of the radio signal of the TDD system and the frequency band of the radio signal of the FDD system are different from each other.

3. A communication system according to claim 2, wherein the frequency band of the TDD radio signal is a millimeter wave frequency band of 20 GHz or more and 300 GHz or less, and the frequency band of the FDD radio signal is the frequency band of 10 GHz or less.

4. In the communication system of claim 2, the wireless relay device comprises a forward link communication unit having a frequency conversion unit that converts the frequency of a forward link signal in the frequency band of the TDD system received from the gateway device to the frequency of the FDD system, a signal sampling unit that samples the signal converted by the frequency conversion unit, and a time signal expansion unit that expands the signal sampled by the signal sampling unit by N times on the time axis, and a reverse link communication unit having a signal sampling unit that samples a reverse link signal in the frequency band of the FDD system received from the terminal device, a time signal compression unit that compresses the signal sampled by the signal sampling unit to 1 / N on the time axis, and a frequency conversion unit that converts the frequency of the signal compressed by the time signal compression unit to the frequency of the TDD system, and the gateway device a forward link communication unit having: a signal sampling unit that samples a forward link signal in the frequency band of the FDD system received from the base station device; a time signal compression unit that compresses the signal sampled by the signal sampling unit to 1 / N on the time axis; and a frequency conversion unit that converts the frequency of the signal compressed by the time signal compression unit to a frequency of the TDD system; and a reverse link communication unit having: a frequency conversion unit that converts the frequency of a reverse link signal in the frequency band of the TDD system received from the wireless relay device to a frequency of the FDD system, a signal sampling unit that samples the signal after conversion by the frequency conversion unit, and a time signal expansion unit that expands the signal sampled by the signal sampling unit by N times on the time axis.

5. A communication system according to claim 1, characterized in that known signals and control data used to control said wireless relay device and known signals and control data used to control said gateway device are placed in each of a plurality of guard times between the communication band time of the forward link and the communication band time of the reverse link which are alternately repeated in said relay wireless section.

6. A communication system according to any one of claims 1 to 5, characterized in that the radio repeater is an airborne repeater type radio repeater mounted on the body of an aircraft or floating body located in the sky, which forms one or more cells towards a ground or sea service area via a service link antenna and communicates wirelessly with one or more terminal devices located in the cell.

7. A communication system according to any one of claims 1 to 5, wherein the gateway device is provided with a plurality of connection sections corresponding to a plurality of base station devices, and the radio relay device forms a plurality of cells using the same frequency corresponding to the plurality of base station devices in the service link, and time-multiplexes radio signals corresponding to the plurality of cells in the relay radio section in the feeder link.

8. A non-regenerative wireless repeater that relays FDD (Frequency Division Duplex) communications between a base station device and a terminal device, comprising means for converting between the FDD signals transmitted and received in the wireless section of the service link between the base station device and the terminal device and the TDD (Time Division Duplex) signals transmitted and received in the relay wireless section between the base station device and a gateway device connected to the base station device, and transmitting and receiving wireless signals in the TDD system in the relay wireless section between the base station device and the gateway device.

9. The radio repeater according to claim 8, wherein the frequency band of the radio signal of the TDD system and the frequency band of the radio signal of the FDD system are different from each other.

10. A radio relay device according to claim 9, wherein the frequency band of the radio signals of the TDD system is a millimeter wave frequency band of 20 GHz or more and 300 GHz or less, and the frequency band of the radio signals of the FDD system is the frequency band of 10 GHz or less.

11. A radio relay device according to claim 9, comprising: a forward link communication unit having a frequency conversion unit that converts the frequency of a forward link signal in the frequency band of the TDD system received from the gateway device to the frequency of the FDD system, a signal sampling unit that samples the signal after conversion by the frequency conversion unit, and a time signal expansion unit that expands the signal sampled by the signal sampling unit by N times on the time axis; and a reverse link communication unit having a signal sampling unit that samples a reverse link signal in the frequency band of the FDD system received from the terminal device, a time signal compression unit that compresses the signal sampled by the signal sampling unit to 1 / N on the time axis, and a frequency conversion unit that converts the frequency of the signal compressed by the time signal compression unit to the frequency of the TDD system.

12. A radio relay device according to claim 8, characterized in that known signals and control data used to control the radio relay device and known signals and control data used to control the gateway device are placed in each of a plurality of guard times between the communication band time of the forward link and the communication band time of the reverse link, which are alternately repeated in the relay radio section.

13. A radio repeater according to any one of claims 8 to 12, characterized in that the radio repeater is an airborne repeater type radio repeater that is installed on the body of an aircraft or floating object located in the sky, forms one or more cells toward a service area on the ground or sea via a service link antenna, and communicates wirelessly with one or more terminal devices located in the cell.

14. A radio relay device according to any one of claims 8 to 12, characterized in that the radio relay device forms a plurality of cells using the same frequency corresponding to a plurality of base station devices in the service link, and time-multiplexes radio signals corresponding to the plurality of cells in the relay radio section in the feeder link.

15. A gateway device that is 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, the gateway device having means for converting FDD signals transmitted to and from the base station device and TDD (Time Division Duplex) signals transmitted in the relay wireless section between the base station device and the wireless relay device, and transmitting and receiving wireless signals in the TDD system in the relay wireless section between the base station device and the wireless relay device.

16. The gateway device according to claim 15, wherein the frequency band of the TDD radio signal and the frequency band of the FDD radio signal are different from each other.

17. A gateway device according to claim 16, wherein the frequency band of the TDD radio signal is a millimeter wave frequency band of 20 GHz or more and 300 GHz or less, and the frequency band of the FDD radio signal is the frequency band of 10 GHz or less.

18. A gateway device according to claim 16, comprising: a forward link communication unit having a signal sampling unit that samples forward link signals in the frequency band of the FDD system received from said base station device; a time signal compression unit that compresses the signals sampled by said signal sampling unit to 1 / N on the time axis; and a frequency conversion unit that converts the frequency of the signals compressed by said time signal compression unit to a frequency for the TDD system; and a reverse link communication unit having a frequency conversion unit that converts the frequency of reverse link signals in the frequency band of the TDD system received from said wireless repeater device to a frequency for the FDD system, a signal sampling unit that samples the signals after conversion by said frequency conversion unit; and a time signal expansion unit that expands the signals sampled by said signal sampling unit by N times on the time axis.

19. A gateway device according to claim 15, characterized in that known signals and control data used to control the wireless relay device and known signals and control data used to control the gateway device are placed in each of a plurality of guard times between the communication band time of the forward link and the communication band time of the reverse link, which are alternately repeated in the relay wireless section.

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