Master station device and analog signal transmission method

Abstract

A master station device is a master station device capable of transmitting and receiving analog signals with a plurality of slave station devices, and includes: an acquisition unit that acquires beam information indicating a beamforming pattern from outside the master station device; a selection unit that selects at least one of the plurality of slave station devices based on the beam information; a transmission unit that performs transmission processing of transmitting a downlink analog signal to the selected slave station device; and a reception unit that performs reception processing of receiving an uplink analog signal from the selected slave station device, wherein the transmission unit performs processing for reflecting the selection result of the selection unit in the transmission processing, and the reception unit performs processing for reflecting the selection result of the selection unit in the reception processing.

Description

Technical Field

[0001] This disclosure relates to a master station device and an analog signal transmission method.

[0002] This application claims priority based on Japanese Patent Application No. 2024-48857, filed on March 26, 2024, and incorporates the entire contents of that application. Background Technology

[0003] Non-patent document 1 (“Beam Scanning of NR SSB”, [online], [Searched on February 27, Reiwa 6], Internet)<URL:https: / / jp.mathworks.com / help / 5g / ug / nr-ssb-beam-sweeping.html> Beamforming technology was disclosed in [the document / article].

[0004] In addition, distributed antenna systems (DAS) are known as a technique for eliminating radio wave blind spots caused by obstacles.

[0005] Existing technical documents

[0006] Non-patent literature

[0007] Non-Patent Document 1: "Beam Scanning of NR SSB", [online], [Searched on February 27, Reiwa 6], Internet<URL:https: / / jp.mathworks.com / help / 5g / ug / nr-ssb-beam-sweeping.html>

[0008] Non-patent literature 2: "5G / NR-Beam Management", [online], [searched on February 27, 2007], Internet<URL:https: / / www.sharetechnote.com / html / 5G / 5G_Phy_BeamManagement.html>

[0009] Non-patent document 3: “5G NR Beam Management SA, NSA | Beam Management In 5G NR”, [online], [searched on February 27, 2007], Internet<URL:https: / / www.rfwireless-world.com / 5G / 5G-NR-Beam-Management.html> Summary of the Invention

[0010] The master station device disclosed herein is a master station device capable of transmitting and receiving analog signals with multiple substation devices, wherein the multiple substation devices transmit and receive RF (Radio Frequency) signals via antennas arranged at intervals. The master station device includes: an acquisition unit for acquiring beam information representing a beamforming mode from outside the master station device; a selection unit for selecting at least one of the multiple substation devices based on the beam information acquired by the acquisition unit; a transmission unit for transmitting downlink analog signals to the substation device; and a receiving unit for receiving uplink analog signals from the substation device. The transmission unit performs downlink signal processing to reflect the selection result of the selection unit for the substation device in the transmission processing, and the receiving unit performs uplink signal processing to reflect the selection result of the selection unit for the substation device in the receiving processing.

[0011] This disclosure can be implemented not only as a master station device with such a characteristic processing unit, but also as a program for causing a computer to execute the characteristic processing steps. Furthermore, this disclosure can be implemented as a semiconductor integrated circuit that implements part or all of the master station device, or as a system including the master station device. Attached Figure Description

[0012] Figure 1 This is a diagram illustrating the configuration of a communication system according to the first embodiment of this disclosure.

[0013] Figure 2 This is a diagram illustrating a configuration example of a remote node in a communication system according to the first embodiment of this disclosure.

[0014] Figure 3 This is a diagram illustrating the configuration of the central node in a communication system according to the first embodiment of this disclosure.

[0015] Figure 4 This is a diagram illustrating the configuration of a remote node in a communication system according to the first embodiment of this disclosure.

[0016] Figure 5 This is a diagram illustrating an example of a correspondence table stored in the storage unit of a remote node according to the first embodiment of this disclosure.

[0017] Figure 6 This is a flowchart illustrating an example of the operation process of a central node in the first embodiment of this disclosure when transmitting and receiving analog signals.

[0018] Figure 7 This is a diagram illustrating the configuration of a communication system according to the second embodiment of this disclosure.

[0019] Figure 8 This is a diagram illustrating the configuration of the central node in the communication system according to the second embodiment of this disclosure.

[0020] Figure 9 This is a diagram illustrating an example of a correspondence table stored in the storage unit of a remote node according to the second embodiment of this disclosure.

[0021] Figure 10 This is a diagram illustrating the configuration of a remote node in a communication system according to the second embodiment of this disclosure.

[0022] Figure 11 This is a diagram illustrating the configuration of a communication system according to the third embodiment of this disclosure.

[0023] Figure 12 This is a diagram illustrating the configuration of the central node in a communication system according to the third embodiment of this disclosure.

[0024] Figure 13 This is a diagram illustrating the configuration of a communication system according to the fourth embodiment of this disclosure.

[0025] Figure 14 This is a diagram illustrating the configuration of the central node in the communication system according to the fourth embodiment of this disclosure. Detailed Implementation

[0026] In the past, technologies have been developed to improve the communication quality of communication systems.

[0027] [The technical problem this disclosure aims to solve]

[0028] In a distributed antenna system, since RF signals are transmitted and received through multiple antennas, the communication quality can sometimes be degraded due to noise superposition caused by the multiplexing of uplink signals.

[0029] This disclosure is made to solve the above-mentioned technical problems, and its purpose is to provide a master station device and an analog signal transmission method that can further improve the communication quality in a communication system.

[0030] [The Effects of This Disclosure]

[0031] According to this disclosure, the communication quality in a communication system can be further improved.

[0032] [Description of embodiments of this disclosure]

[0033] First, the contents of the embodiments of this disclosure will be listed for explanation.

[0034] (1) The master station device involved in the embodiments of this disclosure is a master station device capable of transmitting and receiving analog signals with a plurality of substation devices, wherein the plurality of substation devices transmit and receive RF signals respectively via antennas arranged at intervals. The master station device includes: an acquisition unit that acquires beam information representing a beamforming mode from outside the master station device; a selection unit that selects at least one of the plurality of substation devices based on the beam information acquired by the acquisition unit; a transmission unit that performs transmission processing to transmit downlink analog signals to the substation device; and a receiving unit that performs reception processing to receive uplink analog signals from the substation device. The transmission unit performs downlink signal processing to reflect the selection result of the selection unit for the substation device in the transmission processing, and the receiving unit performs uplink signal processing to reflect the selection result of the selection unit for the substation device in the reception processing.

[0035] By selecting substation devices based on beam information and reflecting the selection results in the transmission and reception processes, analog signal transmission and reception can be selectively performed between the selected substation devices. Therefore, compared to a configuration that transmits analog signals in parallel with all substation devices, the generation of accumulated noise caused by noise included in the RF signals received via each antenna can be suppressed. Consequently, the communication quality in the communication system can be further improved.

[0036] (2) In (1) above, it is also possible that, as the downlink signal processing, the transmitting unit adjusts the level of the downlink analog signal sent to the substation device based on the selection result of the selection unit on the substation device, or it is possible that, as the uplink signal processing, the receiving unit adjusts the level of the uplink analog signal received from the substation device based on the selection result of the selection unit on the substation device.

[0037] Based on this configuration, compared to a configuration that switches the on and off states of analog signal transmission and reception between the substation and the substation based on the selection result of the substation, the level of the analog signal transmitted and received between the substation and the substation can be adjusted more precisely.

[0038] (3) In (2) above, the transmitting unit may also be able to adjust the levels of the multiple downlink analog signals sent to the multiple substation devices selected by the selection unit to different values.

[0039] With this configuration, for example, the level of the downlink analog signal can be adjusted according to the size of the coverage area of ​​the substation device. To this end, the level of the downlink analog signal sent to a substation device with a large coverage area can be adjusted to a larger value to transmit a sufficiently high level of RF signal from that substation device, while the level of the downlink analog signal sent to a substation device with a small coverage area can be adjusted to a smaller value to reduce the power consumption of that substation device.

[0040] (4) In (2) or (3) above, the receiving unit may attenuate the uplink analog signals with a level of a predetermined value or higher among the multiple uplink analog signals received from the multiple substation devices respectively.

[0041] With this configuration, in the event of excessive RF signal input in some substation devices, it is possible to prevent the degradation of uplink communication quality caused by combining multiple uplink analog signals received separately from multiple substation devices.

[0042] (5) In (1) above, the transmitting unit may selectively transmit the downlink analog signal to the substation selected by the selection unit among the plurality of substation devices as the downlink signal processing, or the receiving unit may selectively receive the uplink analog signal from the substation selected by the selection unit among the plurality of substation devices as the uplink signal processing.

[0043] With this configuration, the generation of accumulated noise can be suppressed more reliably.

[0044] (6) In any of (1) to (5) above, the master station device may also include a storage unit that stores correspondence information representing the correspondence between the beamforming mode and the substation device. Alternatively, the selection unit may select at least one of the plurality of substation devices based on the correspondence information and the beam information. Alternatively, the correspondence information may include the substation devices that have established a correspondence with the plurality of beamforming modes.

[0045] Based on this configuration, when a substation device corresponding to multiple beamforming modes is selected, for example, the substation device can be judged accordingly based on the different beamforming modes represented by the beam information.

[0046] (7) In (6) above, the transmitting unit may also send the control signal of the beamforming mode of the RF signal to the substation device that has established a correspondence with the plurality of beamforming modes.

[0047] Based on this configuration, the beamforming mode in the substation device can be controlled according to the different beamforming modes represented by the beam information.

[0048] (8) In any of (1) to (5) above, the master station device may also include a storage unit that stores correspondence information representing the correspondence between the beamforming mode and the substation device. Alternatively, the selection unit may select at least one of the plurality of substation devices based on the correspondence information and the beam information. Alternatively, the beamforming mode and the substation device may be established in a one-to-one correspondence in the correspondence information.

[0049] Based on this configuration, a limited number of beamforming patterns can be used, for example, selecting substations from a larger number of substations to transmit and receive analog signals.

[0050] (9) In any of (1) to (8) above, the master station device may also include a delay processing unit that assigns a delay amount to the downlink analog signal and the uplink analog signal. Alternatively, the delay processing unit may assign a delay amount to the downlink analog signal transmitted by the transmitting unit that is corresponding to the transmission distance between the substation device and the master station device at the transmission destination of the downlink analog signal. Alternatively, the delay processing unit may assign a delay amount to the uplink analog signal received by the receiving unit that is corresponding to the transmission distance between the substation device and the master station device at the transmission source of the uplink analog signal.

[0051] With this configuration, for example, it is possible to suppress timing deviations in the transmission of RF signals in each substation device based on the transmission distance of the downlink analog signal. Furthermore, for example, it is possible to suppress timing deviations in the reception of uplink analog signals in the device at the transmission destination of the uplink analog signal based on the transmission distance of the uplink analog signal.

[0052] (10) In (9) above, the delay processing unit may notify the base station device outside the master station device of the representative value of the transmission delay of the multiple downlink analog signals corresponding to the multiple substation devices respectively, or the sending unit may send the downlink analog signal that has been controlled by the transmission timing based on the representative value in the base station device to the substation device.

[0053] With this configuration, it is possible to distribute the antennas in multiple locations while maintaining the RF signal transmission timing close to that of a device where the antennas are directly connected to the base station.

[0054] (11) The analog signal transmission method disclosed herein is an analog signal transmission method in a master station device capable of transmitting and receiving analog signals with a plurality of substation devices, the plurality of substation devices transmitting and receiving RF signals via distributed antennas, the analog signal transmission method comprising the following steps: acquiring beam information representing a beamforming mode; selecting at least one of the plurality of substation devices based on the acquired beam information; performing a transmission process to transmit a downlink analog signal to the substation device; and performing a reception process to receive an uplink analog signal from the substation device, wherein in the step of performing the transmission process, downlink signal processing is performed to reflect the selection result of the substation device in the transmission process, and in the step of performing the reception process, uplink signal processing is performed to reflect the selection result of the substation device in the reception process.

[0055] In this way, by selecting substation devices based on beam information and reflecting the selection results in the transmission and reception processes, analog signal transmission and reception can be selectively performed between the selected substation devices. Therefore, compared with the method of transmitting analog signals in parallel between all substation devices, the generation of accumulated noise caused by noise included in the RF signals received via each antenna can be suppressed. Consequently, the communication quality in the communication system can be further improved.

[0056] The embodiments of this disclosure will now be described using the accompanying drawings. It should be noted that the same or equivalent reference numerals are used to label the same or equivalent parts in the drawings, and their descriptions will not be repeated. Furthermore, at least some of the embodiments described below can be combined arbitrarily.

[0057] <First Implementation Method>

[0058] [Composition and Basic Movements]

[0059] Figure 1 This is a diagram illustrating the configuration of a communication system according to the first embodiment of this disclosure. (Refer to...) Figure 1 The communication system 401 includes a central node 101 and multiple remote nodes 201. The central node 101 is an example of a master station device. The remote nodes 201 are examples of slave station devices. The communication system 401 is a distributed antenna system. The central node 101 and the remote nodes 201 are interconnected via optical fiber 191. The central node 101 is connected to the base station device 301 via transmission line 181. The transmission line 181 is, for example, a coaxial cable.

[0060] Each remote node 201 has an antenna 211. For example, the antenna 211 is an omnidirectional antenna. The antennas 211 are arranged at intervals. More specifically, the antennas 211 are spatially distributed.

[0061] Figure 2 This is a diagram illustrating a configuration example of a remote node in a communication system according to the first embodiment of this disclosure. (Refer to...) Figure 2 Multiple remote nodes 201 are respectively installed on the ceilings of multiple rooms 82 in building 81. It should be noted that multiple remote nodes 201 can also be installed in a single room 82. RF signals are transmitted and received between the remote nodes 201 and the communication terminal 111 via antenna 211. The communication terminal 111 can be a mobile terminal or a fixed terminal.

[0062] Refer again Figure 1 The central node 101 and the remote node 201 transmit and receive optical signals, including analog signals, via optical fiber 191. Hereinafter, the optical signal transmitted from the central node 101 to the remote node 201 will be referred to as the downlink optical signal, and the optical signal transmitted from the remote node 201 to the central node 101 will be referred to as the uplink optical signal.

[0063] For example, communication system 401 is used as a fronthaul in a mobile communication system operating in TDD (Time Division Duplex) mode. In this case, in communication system 401, downlink period Pd and uplink period Pu are switched and repeated alternately. Downlink period Pd is used for downlink communication where remote node 201 sends RF signals to communication terminal 111, and uplink period Pu is used for uplink communication where remote node 201 receives RF signals from communication terminal 111.

[0064] More specifically, the central node 101 receives an analog signal SId in the IF (Intermediate Frequency) band, which includes communication data, from the base station device 301 via transmission line 181. The central node 101 then transmits a downlink optical signal, including the received analog signal SId, to the remote node 201 via optical fiber 191. The analog signal SId is an example of a downlink analog signal.

[0065] Remote node 201 receives downlink optical signals from central node 101 via optical fiber 191. Remote node 201 extracts an analog signal SId from the received downlink optical signal and performs frequency conversion on the extracted analog signal SId to generate an RF signal SRd. During downlink operation, remote node 201 transmits the generated RF signal SRd to communication terminal 111 via antenna 211.

[0066] Additionally, during uplink, remote node 201 receives an RF signal SRu, which includes communication data, from communication terminal 111. Remote node 201 performs frequency conversion on the RF signal SRu received from communication terminal 111, for example, to generate an analog signal SIu in the IF band. Remote node 201 then transmits the uplink optical signal, including the generated analog signal SIu, to central node 101 via optical fiber 191. The analog signal SIu is an example of an uplink analog signal.

[0067] The central node 101 receives uplink optical signals from the remote node 201 via optical fiber 191. The central node 101 extracts the analog signal SIu from the received uplink optical signal and transmits the extracted analog signal SIu to the base station device 301 via transmission line 181.

[0068] [Technical Issues]

[0069] In a distributed antenna system, since RF signals are transmitted and received through multiple antennas, the communication quality can sometimes be degraded due to noise superposition caused by the multiplexing of uplink signals.

[0070] More specifically, in a distributed antenna system, accumulated noise is generated due to noise included in the RF signals SRu received via each remote node 201. As a result, the communication quality of uplink communication degrades.

[0071] Therefore, the communication system 401 according to the first embodiment of this disclosure solves the above-mentioned technical problems through the following configuration.

[0072] (Composition of central and remote nodes)

[0073] Figure 3 This is a diagram illustrating the configuration of the central node in a communication system according to the first embodiment of this disclosure. (Refer to...) Figure 3 The central node 101 includes a transceiver unit 1, a control unit 2, and a storage unit 3. The transceiver unit 1 is an example of a transmitting unit and also an example of a receiving unit. The control unit 2 is an example of an acquisition unit and also an example of a selection unit. Some or all of the functions of the transceiver unit 1 and the control unit 2 are implemented, for example, by a processing circuit including one or more processors. The storage unit 3 is, for example, a non-volatile memory included in the aforementioned processing circuit.

[0074] The transceiver unit 1 includes a downlink processing unit 11, an uplink processing unit 12, a switching unit 20, and multiple optical transceiver units 30. The switching unit 20 has switches 21 and 22. Each optical transceiver unit 30 has a multiplexing unit 31, a demultiplexing unit 32, an optical modulation unit 33, an optical demodulation unit 34, and an optical coupler 35. The optical coupler 35 in each optical transceiver unit 30 is connected to a different remote node 201 via an optical fiber 191. The transceiver unit 1 performs transmission processing to send an analog signal SId to the remote node 201 and reception processing to receive an analog signal SIu from the remote node 201. Details regarding the transmission and reception processing will be described below.

[0075] The switch 21 has an input terminal connected to the downlink processing unit 11 and multiple output terminals connected to multiple optical transceiver units 30 respectively. The switch 21 can switch the optical transceiver units 30 connected to the downlink processing unit 11.

[0076] The switch 22 has multiple input terminals that are respectively connected to multiple optical transceiver units 30, and an output terminal that is connected to the uplink processing unit 12. The switch 22 can switch the optical transceiver unit 30 connected to the uplink processing unit 12.

[0077] Figure 4 This is a diagram illustrating the configuration of a remote node in a communication system according to the first embodiment of this disclosure. (Refer to...) Figure 4 The remote node 201 includes an optical coupler 41, an optical demodulation unit 42, an optical modulation unit 43, a separation unit 44, a multiplexing unit 45, frequency conversion units 46 and 47, an amplification unit 48 and 49, an RF transceiver unit 50, a control unit 51, and an antenna 211. Some or all of the functions of the control unit 51 are implemented, for example, by a processing circuit including one or more processors.

[0078] (Selection of remote nodes for connection to the destination)

[0079] Refer again Figure 3 In the central node 101, the control unit 2 acquires beam information representing the beamforming mode from outside the central node 101. For example, the control unit 2 receives beam information from the base station device 301.

[0080] More specifically, the base station device 301 generates beam information for beamforming control according to beamforming techniques described in Non-Patent Documents 1, 2, and 3. For example, the beam information includes a BeamID, which serves as an identifier for the beamforming mode according to O-RAN (Open Radio Access Network) specifications. The base station device 301 generates beam information periodically or irregularly and sends the generated beam information to the central node 101.

[0081] If the control unit 2 receives beam information from the base station device 301, it selects at least one remote node 201 from the plurality of remote nodes 201 based on the received beam information. For example, the control unit 2 selects one of the remote nodes 201 that performs the transmission and reception of analog signals SId and SIu based on the beam information.

[0082] Figure 5 This is a diagram illustrating an example of a mapping table stored in the storage unit of a remote node according to the first embodiment of this disclosure. (Refer to...) Figure 5 Storage unit 3 stores a mapping table T1, which represents the correspondence between the BeamID of the beamforming mode and the remote ID that serves as the identifier of the remote node 201. The mapping table T1 is an example of the mapping information.

[0083] exist Figure 5 In the correspondence table T1 shown, a one-to-one correspondence is established between the beamforming mode and the remote node 201. More specifically, in the correspondence table T1, the remote ID of "AAA" corresponds to the Beam ID of "aaa", the remote ID of "BBB" corresponds to the Beam ID of "bbb", the remote ID of "CCC" corresponds to the Beam ID of "ccc", and the remote ID of "DDD" corresponds to the Beam ID of "ddd".

[0084] Based on the correspondence table T1 and beam information, the control unit 2 selects a number of remote nodes 201 that will transmit and receive analog signals SId and SIu. More specifically, if the control unit 2 receives beam information from the base station device 301, it obtains the BeamID from the beam information. Referring to the correspondence table T1 in the storage unit 3, the control unit 2 determines the remote node 201 with a remote ID corresponding to the obtained BeamID as the remote node 201 that will transmit and receive analog signals SId and SIu.

[0085] Refer again Figure 3 If the control unit 2 selects a remote node 201 for transmitting and receiving analog signals SId and SIu, it outputs a switching signal to the transceiver unit 1. This switching signal is used to connect the optical transceiver unit 30 and the base station device 301 corresponding to the selected remote node 201.

[0086] (downstream communication)

[0087] In the central node 101, the transceiver unit 1 performs downlink signal processing to reflect the selection result of the remote node 201 by the control unit 2 in the transmission process. For example, as downlink signal processing, the transceiver unit 1 selectively transmits an analog signal SId to the remote node 201 selected by the control unit 2 from among a plurality of remote nodes 201.

[0088] More specifically, the switch 21 in the switching unit 20 receives a switching signal from the control unit 2, and switches the optical transceiver unit 30 connected to the base station device 301 via the downlink processing unit 11 according to the received switching signal.

[0089] Downlink processing unit 11 receives an analog signal SId, which includes communication data, from base station device 301. During downlink operation, downlink processing unit 11 outputs the received analog signal SId to optical transceiver unit 30 via switch 21. More specifically, downlink processing unit 11 outputs the analog signal SId to one of the plurality of optical transceiver units 30 connected via switch 21.

[0090] The control unit 2 receives TDD information and synchronization information representing uplink period Pu and downlink period Pd from the base station device 301. The control unit 2 generates a digital signal Sdd including the received TDD information and synchronization information, and outputs the generated digital signal Sdd to the optical transceiver unit 30 corresponding to the remote node 201 that performs the transmission and reception of analog signals SId and SIu.

[0091] The multiplexing unit 31 in the optical transceiver unit 30, which is connected to the downlink processing unit 11 via switch 21, performs frequency multiplexing on the analog signal SId received from the downlink processing unit 11 via switch 21 and the digital signal Sdd received from the control unit 2. The multiplexing unit 31 generates an electrical signal after frequency multiplexing of the analog signal SId and the digital signal Sdd and outputs it to the optical modulation unit 33.

[0092] The optical modulation unit 33 in the optical transceiver unit 30, which is connected to the downlink processing unit 11 via switch 21, receives electrical signals from the multiplexing unit 31 and generates a downlink optical signal with wavelength λ1 after optical modulation of the received electrical signals. The optical modulation unit 33 transmits the downlink optical signal to the corresponding remote node 201 via optical coupler 35 and optical fiber 191. The optical modulation unit 33 in the optical transceiver unit 30, which is not connected to the downlink processing unit 11 via switch 21, may be configured to transmit a downlink optical signal of a predetermined strength, excluding the analog signal SId, to the corresponding remote node 201 via optical coupler 35 and optical fiber 191, or it may be configured not to transmit a downlink optical signal.

[0093] Refer again Figure 4 In remote node 201, optical demodulation unit 42 receives downlink optical signals from central node 101 via optical fiber 191 and optical coupler 41. Optical demodulation unit 42 generates an electrical signal with a level corresponding to the intensity of the received downlink optical signal and outputs it to separation unit 44.

[0094] The separation unit 44 separates the analog signal SId and the digital signal Sdd included in the electrical signal received from the optical demodulation unit 42. The separation unit 44 outputs the separated analog signal SId to the frequency conversion unit 46 and the separated digital signal Sdd to the control unit 51.

[0095] The frequency conversion unit 46 generates an RF signal SRd by performing frequency conversion on the analog signal SId received from the separation unit 44 and outputs it to the amplification unit 48.

[0096] The amplification unit 48 amplifies the RF signal SRd received from the frequency conversion unit 46 and outputs the amplified RF signal SRd to the RF transceiver unit 50.

[0097] The control unit 51 acquires TDD information and synchronization information from the digital signal Sdd received from the separation unit 44, and switches the RF signal transmission and reception operations performed by the RF transceiver unit 50 based on the acquired TDD information and synchronization information. More specifically, the control unit 51 generates a TDD switching signal for switching the RF signal transmission and reception operations performed by the RF transceiver unit 50 based on the TDD information and synchronization information, and outputs the generated TDD switching signal to the RF transceiver unit 50.

[0098] According to the TDD switching signal received from the control unit 51, the RF transceiver unit 50 transmits the RF signal SRd received from the amplifier unit 48 to the communication terminal 111 via the antenna 211 during downlink.

[0099] (uplink communication)

[0100] According to the TDD switching signal received from the control unit 51, the RF transceiver unit 50 receives the RF signal SRu from the communication terminal 111 via the antenna 211 during the uplink period. The RF transceiver unit 50 outputs the received RF signal SRu to the amplification unit 49.

[0101] The amplification unit 49 amplifies the RF signal SRu received from the RF transceiver unit 50 and outputs the amplified RF signal SRu to the frequency conversion unit 47.

[0102] The frequency conversion unit 47 generates an analog signal SIu by performing frequency conversion on the RF signal SRu received from the amplification unit 49 and outputs it to the multiplexing unit 45.

[0103] The multiplexing unit 45 receives a digital signal Sdu, including monitoring results such as the temperature of the remote node 201, from the monitoring unit (not shown). The multiplexing unit 45 performs frequency multiplexing on the analog signal SIu received from the frequency conversion unit 47 and the digital signal Sdu received from the monitoring unit (not shown). The multiplexing unit 45 generates an electrical signal after frequency multiplexing the analog signal SIu and the digital signal Sdu and outputs it to the optical modulation unit 43.

[0104] The optical modulation unit 43 receives an electrical signal from the multiplexing unit 45 and generates an uplink optical signal with wavelength λ2 after optical modulation of the received electrical signal. Wavelength λ2 may be the same as or different from wavelength λ1. The optical modulation unit 43 transmits the uplink optical signal to the central node 101 via the optical coupler 41 and the optical fiber 191.

[0105] Refer again Figure 3 In the central node 101, the transceiver unit 1 performs uplink signal processing to reflect the selection result of the remote node 201 by the control unit 2 in the reception processing. For example, as uplink signal processing, the transceiver unit 1 selectively receives the analog signal SIu from the remote node 201 selected by the control unit 2 from a plurality of remote nodes 201.

[0106] More specifically, the switch 22 in the switching unit 20 receives a switching signal from the control unit 2, and switches the optical transceiver 30 connected to the base station device 301 via the uplink processing unit 12 according to the received switching signal.

[0107] The optical demodulation unit 34 in the optical transceiver unit 30 receives uplink optical signals from the corresponding remote node 201 via optical fiber 191 and optical coupler 35. The optical demodulation unit 34 generates an electrical signal with a level corresponding to the intensity of the received uplink optical signal and outputs it to the separation unit 32.

[0108] The separation unit 32 separates the analog signal SIu and the digital signal Sdu from the electrical signal received from the optical demodulation unit 34. The separation unit 44 outputs the separated analog signal SIu to the uplink processing unit 12 via the switch 22, and outputs the separated digital signal Sdu to the control unit 2.

[0109] The uplink processing unit 12 transmits the analog signal SIu received from the optical transceiver unit 30 via the switch 22 to the base station device 301. More specifically, the uplink processing unit 12 receives the analog signal SIu from one of the multiple optical transceiver units 30 connected via the switch 22, and transmits the received analog signal SIu to the base station device 301.

[0110] The control unit 2 acquires monitoring results from the digital signal Sdu received from the separation unit 32 and processes the acquired monitoring results. It should be noted that the control unit 2 may also send the acquired monitoring results to the base station device 301.

[0111] [Action Flow]

[0112] Figure 6 This is a flowchart illustrating an example of the operation process of a central node in the first embodiment of this disclosure when transmitting and receiving analog signals.

[0113] Reference Figure 6 First, the central node 101 begins the transmission processing of the analog signal SId and the reception processing of the analog signal SIu (step S11).

[0114] Next, the central node 101 waits for the arrival of beam information ("No" in step S12). If beam information is received from the base station device 301 ("Yes" in step S12), then based on the received beam information and the correspondence table T1 in the storage unit 3, a plurality of remote nodes 201 are selected to transmit and receive analog signals SId and SIu (step S13).

[0115] Next, the central node 101 performs downlink signal processing to reflect the selection result of the remote node 201 in the transmission processing, and uplink signal processing to reflect the selection result of the remote node 201 in the reception processing. More specifically, the central node 101 connects the optical transceiver unit 30 and the base station device 301 corresponding to the selected remote node 201 via the downlink processing unit 11, the uplink processing unit 12, and switches 21 and 22, thereby transmitting downlink optical signals to the selected remote node 201 and receiving uplink optical signals from the selected remote node 201 (step S14).

[0116] Next, the central node 101 continues to send downlink optical signals to the remote node 201 selected in step S13 and receive uplink optical signals from the remote node 201 until new beam information arrives ("No" in step S12).

[0117] It should be noted that in the communication system 401 according to the first embodiment of this disclosure, the central node 101 and the remote node 201 are configured to transmit and receive optical signals via optical fiber 191, but this is not a limitation. The central node 101 and the remote node 201 may also be configured to transmit and receive analog signals via transmission lines. In this case, the transceiver unit 1 in the central node 101 transmits an electrical signal including the analog signal SId to a remote node 201 via the transmission line, and receives an electrical signal including the analog signal SIu from a remote node 201 via the transmission line.

[0118] Furthermore, in the central node 101 according to the first embodiment of this disclosure, the control unit 2 is configured to select one remote node 201 for transmitting and receiving analog signals SId and SIu, but it is not limited to this. The control unit 2 may also be configured to select two or more remote nodes 201 in the communication system 401 for transmitting and receiving analog signals SId and SIu. In this case, the central node 101 also includes a power divider combined with switches 21 and 22.

[0119] Furthermore, while the remote node 201 according to the first embodiment of this disclosure is configured to include frequency conversion units 46 and 47, it is not limited to this. The remote node 201 may also be configured without frequency conversion units 46 and 47. In this case, for example, the optical transceiver unit 30 in the central node 101 further includes a frequency conversion unit provided in the front stage of the multiplexing unit 31 that generates an RF signal SRd by frequency conversion of the analog signal SId, and a frequency conversion unit provided in the rear stage of the separation unit 32 that generates an analog signal SIu by frequency conversion of the RF signal SRu. It should be noted that when the optical transceiver unit 30 does not have a frequency conversion unit, the downlink processing unit 11 may also receive the RF signal SRd from the base station device 301 and output the received RF signal SRd to the optical transceiver unit 30 via the switch 21. In addition, when the optical transceiver unit 30 does not have a frequency conversion unit, the uplink processing unit 12 may also receive the RF signal SRu from the optical transceiver unit 30 and send the received RF signal SRu to the base station device 301. In this case, the base station device 301 generates an analog signal SIu or a baseband signal by performing frequency conversion on the RF signal SRu received from the central node 101.

[0120] As described above, in the central node 101 according to the first embodiment of this disclosure, the control unit 2 acquires beam information representing the beamforming mode from outside the central node 101. Based on the acquired beam information, the control unit 2 selects at least one of a plurality of remote nodes 201. The transceiver unit 1 performs downlink signal processing and uplink signal processing to reflect the selection result of the remote node 201 by the control unit 2 in the transmission processing.

[0121] In this way, by selecting remote nodes 201 based on beam information and reflecting the selection result in the transmission and reception processes, analog signals SId and SIu can be selectively transmitted and received between the selected remote nodes 201. Therefore, compared to the configuration of transmitting analog signals SId and SIu in parallel between all remote nodes 201, the generation of accumulated noise caused by noise included in the RF signal SRu received via each antenna 211 can be suppressed. Thus, the communication quality in the communication system 401 can be further improved. In addition, since the remote nodes 201 can be selected using the existing mechanism of transmitting beam information from the base station device 301 for beamforming, the content of the transmission and reception processing of analog signals SId and SIu can be switched without significantly changing the configuration of the existing base station device 301.

[0122] Furthermore, in the central node 101, the transceiver unit 1 only sends the analog signal SId to the remote node 201 selected by the control unit 2, and only receives the analog signal SIu from the remote node 201 selected by the control unit 2. More specifically, the control unit 2 outputs a switching signal to the switching unit 20, which connects the optical transceiver unit 30, downlink processing unit 11, and uplink processing unit 12 corresponding to the remote node 201 that performs the transmission and reception of analog signals SId and SIu. The switch 21 in the switching unit 20 switches the optical transceiver unit 30 connected to the base station device 301 via the downlink processing unit 11 according to the switching signal received from the control unit 2. The switch 22 in the switching unit 20 switches the optical transceiver unit 30 connected to the base station device 301 via the uplink processing unit 12 according to the switching signal received from the control unit 2.

[0123] With this configuration, the analog signal SId received from the base station device 301 can be selectively sent to the remote node 201 selected by the control unit 2 without notifying the remote node 201 of the selection result of the control unit 2, and the analog signal SIu received from the remote node 201 selected by the control unit 2 can be selectively sent to the base station device 301. Therefore, since it is unnecessary to include a configuration in the remote node 201 to reflect the selection result of the control unit 2, the configuration of the remote node 201 can be simplified.

[0124] Next, other embodiments of this disclosure will be described using the accompanying drawings. It should be noted that the same or equivalent reference numerals are used to label the same or equivalent parts in the drawings, and their descriptions will not be repeated.

[0125] <Second Implementation Method>

[0126] Compared to the communication system 401 of the first embodiment, this embodiment relates to a communication system 402 that controls beamforming modes. Except for the following description, it is the same as the communication system 401 of the first embodiment.

[0127] Figure 7 This is a diagram illustrating the configuration of a communication system according to the second embodiment of this disclosure. (Refer to...) Figure 7 Compared to communication system 401, communication system 402 has a central node 102 replacing central node 101 and a remote node 202 replacing remote node 201. Compared to remote node 201, remote node 202 has an antenna 212 replacing antenna 211. For example, antenna 212 is a directional antenna.

[0128] Figure 8 This is a diagram illustrating the configuration of the central node in a communication system according to the second embodiment of this disclosure. (Refer to...) Figure 8 Compared with the central node 101, the central node 102 has a control unit 4 instead of the control unit 2, and a storage unit 5 instead of the storage unit 3.

[0129] Figure 9 This is a diagram illustrating an example of a mapping table stored in the storage unit of a remote node according to the second embodiment of this disclosure. (Refer to...) Figure 9 Storage unit 5 stores a mapping table T2, which represents the correspondence between BeamID, Remote ID, and Mode ID representing the beamforming mode. Mapping table T2 is an example of mapping information.

[0130] Figure 9 The mapping table T2 shown includes remote nodes 202 that correspond to multiple beamforming modes. More specifically, in mapping table T2, the remote ID of "CCC" corresponds to the BeamID of "ccc" and the BeamID of "ddd". Additionally, in mapping table T2, the mode ID of "111" corresponds to the BeamID of "ccc", and the mode ID of "222" corresponds to the BeamID of "ddd".

[0131] Based on the correspondence table T2 and the beam information, the control unit 4 selects a remote node 202 from among multiple remote nodes 202 to transmit and receive analog signals SId and SIu. More specifically, if the control unit 4 receives beam information from the base station device 301, it obtains the BeamID from the beam information. The control unit 4 then refers to the correspondence table T2 in the storage unit 5 and selects a remote node 202 that has a remote ID corresponding to the obtained BeamID.

[0132] If the BeamID obtained from the beam information is "ccc", the control unit 4 identifies the remote node 202 with the remote ID "CCC" as the remote node 202 for transmitting and receiving analog signals SId and SIu, and obtains the mode ID "111" from the correspondence table T2. Then, the control unit 4 outputs a switching signal to switches 21 and 22, which connects the optical transceiver unit 30, downlink processing unit 11, and uplink processing unit 12 corresponding to the remote node 202 with the remote ID "CCC". In addition, the control unit 4 outputs a digital signal Sdd, which includes beam control information representing the obtained mode ID, in addition to TDD information and synchronization information, to the optical transceiver unit 30. The beam control information is an example of a control signal that controls the beamforming mode of RF signals SRd and SRu.

[0133] Furthermore, if the BeamID obtained from the beam information is "ddd", the control unit 4 identifies the remote node 202 with the remote ID "CCC" as the remote node 202 that performs the transmission and reception of analog signals SId and SIu, and obtains the mode ID "222" from the correspondence table T2. Then, the control unit 4 outputs a switching signal to switches 21 and 22, which is used to connect the optical transceiver unit 30, downlink processing unit 11, and uplink processing unit 12 corresponding to the remote node 202 with the remote ID "DDD". In addition, the control unit 4 outputs a digital signal Sdd, which includes beam control information representing the obtained mode ID in addition to TDD information and synchronization information, to the optical transceiver unit 30.

[0134] Refer again Figure 8 The transceiver unit 1 further transmits beam control information to the remote node 202. More specifically, the multiplexing unit 31 in the optical transceiver unit 30 performs frequency multiplexing on the analog signal SId received from the downlink processing unit 11 via the switch 21 and the digital signal Sdd received from the control unit 4. The multiplexing unit 31 generates an electrical signal after frequency multiplexing the analog signal SId and the digital signal Sdd and outputs it to the optical modulation unit 33.

[0135] The optical modulation unit 33 receives an electrical signal from the multiplexing unit 31 and generates a downlink optical signal with wavelength λ1 after optical modulation of the received electrical signal. The optical modulation unit 33 transmits the downlink optical signal to the remote node 202 with the remote ID "CCC" via the optical coupler 35 and the optical fiber 191.

[0136] Figure 10 This is a diagram illustrating the configuration of a remote node in a communication system according to the second embodiment of this disclosure. (Refer to...) Figure 10 Compared to remote node 201, remote node 202 has a control unit 52 instead of control unit 51.

[0137] In the remote node 202 with the remote ID "CCC", the control unit 52 receives the digital signal Sdd from the separation unit 44 and obtains beam control information from the received digital signal Sdd.

[0138] The control unit 52 determines the transmission and reception range, i.e. the coverage area, of the RF signals Sru and Srd of the antenna 212 based on the acquired beam control information, for example, without increasing the power consumption in the remote node 202.

[0139] More specifically, when the acquired beam control information includes a mode ID of "111", the control unit 52 controls the antenna 212 to transmit and receive RF signals Sru and Srd in the coverage area R1. Conversely, when the acquired beam control information includes a mode ID of "222", the control unit 52 controls the antenna 212 to transmit and receive RF signals Sru and Srd in a coverage area R2 that is different from the coverage area R1.

[0140] It should be noted that in the central node 102 according to the second embodiment of this disclosure, the transceiver unit 1 is configured to send beam control information to the remote node 202, but it is not limited to this. The transceiver unit 1 may also be configured not to send beam control information to the remote node 202. In this case, the control unit 4 outputs a digital signal Sdd, which includes TDD information and synchronization information but does not include beam control information, to the optical transceiver unit 30. Alternatively, in this case, the control unit 4 may also be configured to output a digital signal Sdd, which includes control information instead of beam control information, to the optical transceiver unit 30. This control information performs corresponding control on the remote node 202 other than beamforming according to different mode IDs.

[0141] Next, other embodiments of this disclosure will be described using the accompanying drawings. It should be noted that the same or equivalent reference numerals are used to label the same or equivalent parts in the drawings, and their descriptions will not be repeated.

[0142] <Third Implementation Method>

[0143] Compared to the communication system 401 of the first embodiment, this embodiment relates to a communication system 403 that performs timing control of analog signals SId and SIu. Except for the following description, it is the same as the communication system 401 of the first embodiment.

[0144] Figure 11 This is a diagram illustrating the configuration of a communication system according to the third embodiment of this disclosure. (Refer to...) Figure 11 Compared with communication system 401, communication system 403 has a central node 103 to replace central node 101.

[0145] Figure 12This is a diagram illustrating the configuration of the central node in a communication system according to the third embodiment of this disclosure. (Refer to...) Figure 12 Compared to the central node 101, the central node 103 has a transceiver unit 6 instead of the transceiver unit 1, and a control unit 7 instead of the control unit 2. The control unit 7 is an example of an acquisition unit, an example of a selection unit, and an example of a delay processing unit. Compared to the transceiver unit 1, the transceiver unit 6 includes a downlink processing unit 13 instead of the downlink processing unit 11, and includes an uplink processing unit 14 instead of the uplink processing unit 12.

[0146] Based on the correspondence table T1 and the beam information, the control unit 7 selects at least one remote node 201 from a plurality of remote nodes 201. More specifically, if the control unit 7 receives beam information from the base station device 301, it obtains the BeamID from the beam information. Referring to the correspondence table T1 in the storage unit 3, the control unit 7 determines the remote node 201 with a remote ID corresponding to the obtained BeamID as the remote node 201 for transmitting and receiving analog signals SId and SIu.

[0147] (Delay control)

[0148] As timing control for the analog signal SId, the control unit 7 performs delay control on the analog signal SId transmitted by the transceiver unit 6, applying a delay amount Dt corresponding to the transmission distance between the remote node 201 and the central node 103 at the destination of the analog signal SId. Similarly, as timing control for the analog signal SIu, the control unit 7 performs delay control on the analog signal SIu received by the transceiver unit 6, applying a delay amount Dt corresponding to the transmission distance between the remote node 201 and the central node 103 at the source of the analog signal SIu.

[0149] For example, the storage unit 3 stores a delay table representing the correspondence between remote nodes 201 and delay amounts Dt. The delay amount Dt in the delay table is preset, for example, based on the length of the optical fiber 191 between the central node 103 and the corresponding remote node 201. More specifically, the delay amount Dt in the delay table is set such that the sum of the delay amount Dt of the analog signals SId and SIu assigned by the control unit 7 and the transmission delay amount Df of the analog signals SId and SIu in the optical fiber 191 is equal to the transmission delay amount Dfmax of the analog signals SId and SIu in the longest optical fiber 191 among the plurality of optical fibers 191 in the communication system 403.

[0150] If the control unit 7 determines that the remote node 201 is transmitting and receiving analog signals SId and SIu, it refers to the delay table in the storage unit 3 and obtains the delay amount Dt corresponding to the determined remote node 201. Then, the control unit 7 outputs a switching signal to switches 21 and 22, which is used to connect the optical transceiver unit 30, downlink processing unit 11, and uplink processing unit 14 corresponding to the determined remote node 201. In addition, the control unit 7 outputs a delay indication indicating the obtained delay amount Dt to the downlink processing unit 13 and the uplink processing unit 14.

[0151] The downlink processing unit 13, according to the delay instruction received from the control unit 7, applies a delay of Dt to the analog signal SId received from the base station device 301. More specifically, the downlink processing unit 13 includes circuitry such as a delay line for applying the delay to the analog signal SId. During downlink operation Pd, the downlink processing unit 13 performs delay processing to apply the delay of Dt to the analog signal SId, and outputs the delayed analog signal SId to the optical transceiver unit 30 via switch 21. This suppresses timing deviations in the transmission of the RF signal SRd in each remote node 201 based on the length of the optical fiber 191.

[0152] The uplink processing unit 14, according to the delay instruction received from the control unit 7, applies a delay amount Dt to the analog signal SIu received from the optical transceiver unit 30 via the switch 22. More specifically, the uplink processing unit 14 includes circuitry such as a delay line for applying the delay to the analog signal SIu. During the uplink period, the uplink processing unit 14 performs delay processing to apply the delay amount Dt to the analog signal SIu and sends the delayed analog signal SIu to the base station device 301. This suppresses timing deviations in the reception of the analog signal SIu in the base station device 301 based on the length of the optical fiber 191.

[0153] (Timed control for sending and receiving)

[0154] The control unit 7 notifies the base station device 301 of representative values ​​of multiple transmission delay amounts Df corresponding to the multiple remote nodes 201 respectively. For example, as a representative value of the transmission delay amount Df, the control unit 7 notifies the base station device 301 of the transmission delay amount Dfmax.

[0155] Based on the transmission delay amount Dfmax notified from the control unit 7, the base station device 301 performs timing control for transmitting analog signal SId and timing control for receiving analog signal SIu.

[0156] More specifically, as a transmission timing control, the base station device 301, for example, transmits the analog signal SId to the central node 103 at a timing Tt that is earlier than the transmission delay amount Dfmax of the RF signal SRd when the antenna 211 is directly connected to the base station device 301.

[0157] The transceiver unit 6 in the central node 103 transmits the analog signal SId, which has undergone transmission timing control based on the transmission delay Df in the base station device 301, to the remote node 201. More specifically, the downlink processing unit 13 in the transceiver unit 6 receives the analog signal SId with transmission timing control from the base station device 301 and outputs the received analog signal SId to the optical transceiver unit 30 via switch 21. This allows the transmission timing of the RF signal SRd in the remote node 201 to approximate the transmission timing of the RF signal SRd when the antenna 211 is directly connected to the base station device 301.

[0158] Furthermore, as a timing control for reception, the base station device 301 performs analog signal SIu reception processing, for example, at a timing Tr that is later than the reception timing of the RF signal SRu (when the antenna 211 is directly connected to the base station device 301) by a transmission delay amount Dfmax. More specifically, the base station device 301 receives the signal arriving from the central node 103 as the analog signal SIu at this timing Tr. Therefore, the base station device 301 can receive the analog signal SIu more accurately.

[0159] It should be noted that in the central node 103 of the third embodiment of this disclosure, the delay amount Dt in the delay table is configured to be preset based on the length of the optical fiber 191 between the central node 103 and the corresponding remote node 201, but it is not limited to this. The delay amount Dt may also be preset based on the RTT (Round Trip Time) between the central node 103 and the remote node 201.

[0160] More specifically, before the communication system 403 operates, the control unit 7 generates a digital signal Sdd including a predetermined test signal and outputs the generated digital signal Sdd to the optical transceiver unit 30. The remote node 201 acquires the test signal from the digital signal Sdd, generates a digital signal Sdu including the acquired test signal, and transmits an uplink signal including the digital signal Sdu to the central node 103 via optical fiber 191. The control unit 7 acquires the test signal from the digital signal Sdu received from the separation unit 32 and calculates the RTT based on the difference between the output timing and the acquisition timing of the test signal. The control unit 7 calculates the RTT for each remote node 201 and, based on the calculated RTT, calculates the transmission delay Df for each remote node 201. Then, the control unit 7 sets the delay Dt for each remote node 201 based on the calculated transmission delay Df.

[0161] Furthermore, in the communication system 403 according to the third embodiment of this disclosure, it is configured such that the control unit 7 in the central node 103 performs delay control and the base station device 301 performs transmit / receive timing control, but it is not limited to this. In the communication system 403, it is also possible that the control unit 7 performs delay control while the base station device 301 does not perform transmit / receive timing control. Alternatively, in the communication system 403, it is also possible that the base station device 301 performs transmit / receive timing control while the control unit 7 does not perform delay control.

[0162] However, based on the configuration of both delay control and transmit / receive timing control, it is possible to roughly adjust the transmission timing of the RF signal Srd based on the representative value of the transmission delay Df, and to fine-tune the transmission timing of the RF signal Srd based on the transmission delay Df in each optical fiber 191. Therefore, it is possible to more accurately make the transmission timing of the RF signal Srd in each remote node 201 consistent with the transmission timing of the RF signal Srd when the antenna 211 is directly connected to the base station device 301.

[0163] Next, other embodiments of this disclosure will be described using the accompanying drawings. It should be noted that the same or equivalent reference numerals are used to label the same or equivalent parts in the drawings, and their descriptions will not be repeated.

[0164] <Fourth Implementation Method>

[0165] Compared to the communication system 401 of the first embodiment, this embodiment relates to a communication system 404 that adjusts the levels of analog signals SId and SIu based on the selection result of the remote node 201. Except for the following description, it is the same as the communication system 401 of the first embodiment.

[0166] Figure 13 This is a diagram illustrating the configuration of a communication system according to the fourth embodiment of this disclosure. (Refer to...) Figure 13 Compared with communication system 401, communication system 404 has a central node 104 to replace central node 101.

[0167] Figure 14 This is a diagram illustrating the configuration of the central node in the communication system according to the fourth embodiment of this disclosure. (Refer to...) Figure 14 Compared to the central node 101, the central node 104 has a transceiver unit 8 instead of the transceiver unit 1. Compared to the transceiver unit 1, the transceiver unit 8 includes an optical transceiver unit 60 instead of the optical transceiver unit 30, does not include the switching unit 20, and also includes a splitter 71 and a multiplexer 72. Compared to the optical transceiver unit 30, the optical transceiver unit 60 also has variable ATTs 61 and 62 and a setting unit 63. The transceiver unit 8 performs transmission processing of the analog signal SId to the remote node 201 and reception processing of the analog signal SIu from the remote node 201.

[0168] (downstream communication)

[0169] Downlink processing unit 11 receives an analog signal SId, which includes communication data, from base station device 301. During downlink operation, downlink processing unit 11 outputs the received analog signal SId to distributor 71.

[0170] The distributor 71 distributes the analog signal SId received from the downlink processing unit 11 to each optical transceiver unit 60.

[0171] The variable ATT 61 in the optical transceiver unit 60 attenuates the analog signal SId received from the downlink processing unit 11. The amount of attenuation of the analog signal SId in the variable ATT 61 is set by the setting unit 63.

[0172] The multiplexing unit 31 performs frequency multiplexing on the analog signal SId that has passed through the variable ATT 61 and the digital signal Sdd received from the control unit 2. The multiplexing unit 31 generates an electrical signal after frequency multiplexing of the analog signal SId and the digital signal Sdd and outputs it to the optical modulation unit 33.

[0173] The optical modulation unit 33 receives an electrical signal from the multiplexing unit 31 and generates a downlink optical signal with wavelength λ1 after optical modulation of the received electrical signal. The optical modulation unit 33 transmits the downlink optical signal to the corresponding remote node 201 via the optical coupler 35 and the optical fiber 191.

[0174] (uplink communication)

[0175] The optical demodulation unit 34 receives uplink optical signals from the corresponding remote node 201 via optical fiber 191 and optical coupler 35. The optical demodulation unit 34 generates an electrical signal with a level corresponding to the intensity of the received uplink optical signal and outputs it to the separation unit 32.

[0176] The separation unit 32 separates the analog signal SIu and the digital signal Sdu included in the electrical signal received from the optical demodulation unit 34, and outputs the separated analog signal SIu to the variable ATT 62 and the setting unit 63, and outputs the separated digital signal Sdu to the control unit 2.

[0177] The variable ATT 62 attenuates the analog signal SIu received from the separation unit 32. The amount of attenuation of the analog signal SIu in the variable ATT 62 is set by the setting unit 63.

[0178] The multiplexer 72 combines the analog signals SIu that have passed through the variable ATT 62 in each optical transceiver unit 60, and outputs the combined analog signal SIu to the uplink processing unit 12.

[0179] The uplink processing unit 12 sends the analog signal SIu received from the multiplexer 72 to the base station device 301.

[0180] (Adjustment of attenuation)

[0181] If the control unit 2 receives beam information from the base station device 301, it selects at least one remote node 201 from the plurality of remote nodes 201 based on the received beam information. The control unit 2 outputs selection information, which represents the remote ID as the identifier of the selected remote node 201, to each optical transceiver unit 60 in the transceiver unit 8.

[0182] The transceiver unit 8 performs downlink and uplink signal processing to reflect the selection result of the remote node 201 by the control unit 2 in the transmission process. For example, as downlink signal processing, the transceiver unit 8 adjusts the level of the analog signal SId transmitted to the remote node 201 based on the selection result of the remote node 201 by the control unit 2. Similarly, as uplink signal processing, the transceiver unit 8 adjusts the level of the analog signal SIu received from the remote node 201 based on the selection result of the remote node 201 by the control unit 2.

[0183] More specifically, the setting unit 63 in the optical transceiver unit 60 receives selection information from the control unit 2, and determines, based on the received selection information, whether the remote node 201 corresponding to the optical transceiver unit 60 is selected by the control unit 2.

[0184] When the remote node 201 corresponding to the optical transceiver unit 60 is selected by the control unit 2, the setting unit 63 in the optical transceiver unit 60 sets the attenuation of the variable ATTs 61 and 62 in the optical transceiver unit 60 to a predetermined setting value Von. The setting value Von is, for example, zero. The variable ATT 61, with its attenuation set to zero, does not attenuate the analog signal SId received from the downlink processing unit 11, allowing it to pass through.

[0185] On the other hand, when the remote node 201 corresponding to the optical transceiver unit 60 is not selected by the control unit 2, the setting unit 63 in the optical transceiver unit 60 sets the attenuation of the variable ATTs 61 and 62 in the optical transceiver unit 60 to a predetermined setting value Voff. The setting value Voff is a value greater than zero. The variable ATT 61 with the attenuation set to the setting value Voff causes the analog signal SId received from the downlink processing unit 11 to attenuate and pass through.

[0186] For example, the transceiver unit 8 can adjust the levels of multiple analog signals SId transmitted to multiple remote nodes 201 selected by the control unit 2 to different values. More specifically, when the remote node 201 corresponding to the optical transceiver unit 60 is selected by the control unit 2, the setting unit 63 in the optical transceiver unit 60 sets the attenuation of the variable ATT 61 in the optical transceiver unit 60 to a setting value Von corresponding to the size of the coverage area of ​​the remote node 201.

[0187] Specifically, when the size of the coverage area of ​​the corresponding remote node 201 is greater than or equal to a predetermined value Vs, the setting unit 63 in the optical transceiver unit 60 sets the attenuation of the variable ATT 61 in the optical transceiver unit 60 to a set value Von1. Conversely, when the size of the coverage area of ​​the corresponding remote node 201 is less than the predetermined value Vs, the setting unit 63 in the optical transceiver unit 60 sets the attenuation of the variable ATT 61 in the optical transceiver unit 60 to a set value Von2, which is greater than the set value Von1.

[0188] For example, the transceiver unit 8 attenuates analog signals SIu with a level above a predetermined value from among the multiple analog signals SIu received from the multiple remote nodes 201. More specifically, the setting unit 63 in the optical transceiver unit 60 corresponding to the remote node 201 selected by the control unit 2 compares the level of the analog signal SIu received from the separation unit 32 with a predetermined threshold Vth. If the level of the analog signal SIu received from the separation unit 32 is above the threshold Vth, the setting unit 63 adjusts the attenuation amount of the variable ATT 62 so that the level of the analog signal SIu after attenuation by the variable ATT 62 is the threshold Vth.

[0189] It should be noted that in the central node 104 of the fourth embodiment of this disclosure, the optical transceiver unit 60 in the transceiver unit 8 is configured to have variable ATTs 61 and 62, but it is not limited to this. The optical transceiver unit 60 may also have a variable amplifier that amplifies the analog signal SId received from the downlink processing unit 11 and a variable amplifier that amplifies the analog signal SIu received from the separation unit 32 instead of the variable ATTs 61 and 62. In this case, the setting unit 63 sets the amplification of the variable amplifier.

[0190] Furthermore, in the central node 104 according to the fourth embodiment of this disclosure, the setting unit 63 in the optical transceiver unit 60 is configured to set the attenuation of the variable ATT 61 in the optical transceiver unit 60 to a setting value Von corresponding to the size of the coverage area of ​​the remote node 201, but it is not limited to this. The setting unit 63 may also be configured to set the attenuation of the variable ATT 61 in the optical transceiver unit 60 to a predetermined value regardless of the size of the coverage area of ​​the remote node 201 when the corresponding remote node 201 is selected by the control unit 2.

[0191] Furthermore, in the central node 104 according to the fourth embodiment of this disclosure, the setting unit 63 in the optical transceiver unit 60 is configured to adjust the attenuation amount of the variable ATT 62 when the level of the analog signal SIu received from the separation unit 32 is above the threshold Vth, so that the level of the analog signal SIu after attenuation by the variable ATT 62 is the threshold Vth, but it is not limited to this. The setting unit 63 may also be configured not to adjust the attenuation amount of the variable ATT 62 corresponding to the level of the analog signal SIu received from the separation unit 32.

[0192] Alternatively, the setting unit 63 could be configured to adjust the attenuation of the variable ATT 62 so that the level of the analog signal SIu received from the separation unit 32 is a threshold Vth, and adjust the attenuation of at least one of the variable ATTs 61 and 62 according to the quality of the analog signal SIu received from the separation unit 32. This allows for adjustment of the levels of the analog signals SId and SIu corresponding to the remote node 201 based on the occurrence of interference in the remote node 201, thereby improving communication quality.

[0193] It should be understood that the above embodiments are exemplary and not limiting in all respects. The scope of the invention is shown not by the foregoing description but by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0194] Each process (function) in the above-described embodiments is implemented by a processing circuit including one or more processors. This processing circuit may also be composed of integrated circuits that, in addition to the one or more processors, incorporate one or more memories, various analog circuits, and various digital circuits. The one or more memories store programs (commands) that cause the one or more processors to execute the above processes. The one or more processors may execute the above processes according to the programs read from the one or more memories, or they may execute the above processes according to logic circuits pre-designed to execute the above processes. The processors may be various processors suitable for computer control, such as CPUs (Central Processing Units), GPUs (Graphics Processing Units), DSPs (Digital Signal Processors), FPGAs (Field Programmable Gate Arrays), and ASICs (Application Specific Integrated Circuits). It should be noted that physically separate processors may also cooperate to execute the above processes. For example, the processors located in multiple physically separate computers can also cooperate to perform the aforementioned processes via networks such as LANs (Local Area Networks), WANs (Wide Area Networks), and the Internet. The programs can be installed into the memory from external server devices via these networks, or they can be circulated in a state stored on recording media such as CD-ROMs (Compact Disc Read Only Memory), DVD-ROMs (Digital Versatile Disk Read Only Memory), and semiconductor memory, and installed into the memory from these recording media.

[0195] The above description includes the features noted below.

[0196] [Postscript 1]

[0197] A master station device is capable of transmitting and receiving analog signals with multiple slave station devices, wherein the multiple slave station devices transmit and receive RF signals respectively via antennas arranged at intervals. Equipped with processing circuitry, The processing circuit Beam information representing the beamforming mode is acquired from outside the main station device. Based on the acquired beam information, at least one of the plurality of substation devices is selected. The process of transmitting downlink analog signals to the substation device is performed. Perform reception processing of uplink analog signals received from the substation device. Downlink signal processing is performed to reflect the selection result of the substation device in the transmission process. Uplink signal processing is performed to reflect the selection result of the substation device in the receiving process.

[0198] Explanation of reference numerals in the attached figures

[0199] 1, 6, and 8 Receiving and Dispatch Departments

[0200] 2, 4, 7 Control Section

[0201] 3, 5 storage units

[0202] Downlink Processing Departments 11 and 13

[0203] 12, 14 Uplink Processing Department

[0204] 20 Switching Unit

[0205] Switches 21 and 22

[0206] 30 and 60 optical transceiver units

[0207] 31 Reuse Department

[0208] 32 Separation Section

[0209] 33 Optical Modulation Section

[0210] 34 Optical Demodulation Section

[0211] 35 Optical Coupler

[0212] 41 Optical Coupler

[0213] 42 Optical Demodulation Section

[0214] 43 Optical Modulation Section

[0215] 44 Separation Section

[0216] 45 Reuse Section

[0217] 46, 47 Frequency Conversion Section

[0218] Enlarged sections 48 and 49

[0219] 50 RF transceiver unit

[0220] 51, 52 Control Department

[0221] 61, 62 Variable ATT

[0222] 63 Setting Department

[0223] 71 Distributor

[0224] 72-wave combiner

[0225] 81 buildings

[0226] Room 82

[0227] Central nodes 101, 102, 103, and 104

[0228] 111 Communication Terminal

[0229] 181 transmission line

[0230] 191 fiber optic cable

[0231] 201 and 202 remote nodes

[0232] 211 and 212 antennas

[0233] 301 base station equipment

[0234] 401, 402, 403, 404 communication systems

[0235] Table of correspondences between T1 and T2

[0236] R1 and R2 coverage areas.

Claims

1. A master station device capable of transmitting and receiving analog signals with multiple substation devices, wherein the multiple substation devices transmit and receive RF signals respectively via antennas arranged at intervals, the master station device comprising: The acquisition unit acquires beam information representing the beamforming mode from outside the main station device; The selection unit selects at least one of the plurality of substation devices based on the beam information acquired by the acquisition unit. The transmitting unit performs the transmission processing of downlink analog signals to the substation device; as well as The receiving unit performs reception processing of uplink analog signals received from the substation device. The transmitting unit performs downlink signal processing to reflect the selection result of the selection unit for the substation device in the transmitting process. The receiving unit performs uplink signal processing to reflect the selection result of the selection unit for the substation device in the receiving process.

2. The master station device according to claim 1, wherein, As part of the downlink signal processing, the transmitting unit adjusts the level of the downlink analog signal transmitted to the substation device based on the selection result of the selection unit for the substation device. As part of the uplink signal processing, the receiving unit adjusts the level of the uplink analog signal received from the substation device based on the selection result of the selection unit on the substation device.

3. The master station device according to claim 2, wherein, The transmitting unit is capable of adjusting the levels of multiple downlink analog signals sent to multiple substation devices selected by the selection unit to different values.

4. The master station device according to claim 2 or 3, wherein, The receiving unit attenuates the uplink analog signals with a level above a predetermined value among the multiple uplink analog signals received from the multiple substation devices.

5. The master station device according to claim 1, wherein, As part of the downlink signal processing, the transmitting unit selectively transmits the downlink analog signal to the substation device selected by the selection unit among the plurality of substation devices. As part of the uplink signal processing, the receiving unit selectively receives the uplink analog signal from the substation selected by the selection unit from among the plurality of substation devices.

6. The master station device according to any one of claims 1 to 5, wherein, The master station device also includes a storage unit, which stores corresponding information representing the correspondence between the beamforming mode and the substation device. Based on the corresponding information and the beam information, the selection unit selects at least one of the plurality of substation devices. The corresponding information includes the substation devices that have been established with multiple beamforming modes.

7. The master station device according to claim 6, wherein, The transmitting unit also sends a control signal for controlling the beamforming mode of the RF signal to the substation device that has established a correspondence with the plurality of beamforming modes.

8. The master station device according to any one of claims 1 to 5, wherein, The master station device also includes a storage unit, which stores corresponding information representing the correspondence between the beamforming mode and the substation device. Based on the corresponding information and the beam information, the selection unit selects at least one of the plurality of substation devices. In the corresponding information, the beamforming mode is established in a one-to-one correspondence with the substation device.

9. The master station device according to any one of claims 1 to 8, wherein, The master station device also includes a delay processing unit, which assigns a delay to the downlink analog signal and the uplink analog signal. The delay processing unit assigns a delay to the downlink analog signal transmitted by the transmitting unit, corresponding to the transmission distance between the substation device and the master station device at the destination of the downlink analog signal transmission. The delay processing unit assigns a delay amount to the uplink analog signal received by the receiving unit, corresponding to the transmission distance between the substation device and the master station device at the source of the uplink analog signal.

10. The master station device according to claim 9, wherein, The delay processing unit notifies the external base station device of the representative values ​​of the transmission delay of the multiple downlink analog signals corresponding to the multiple substation devices. The transmitting unit sends the downlink analog signal, which has been controlled by the transmission timing based on the representative value in the base station device, to the substation device.

11. An analog signal transmission method, which is an analog signal transmission method in a master station device capable of transmitting and receiving analog signals between itself and multiple substation devices, wherein the multiple substation devices transmit and receive RF signals via distributed antennas, the analog signal transmission method comprising the following steps: Obtain beam information representing the beamforming mode; Based on the acquired beam information, at least one of the plurality of substation devices is selected; Perform the transmission processing of downlink analog signals to the substation device; as well as Perform reception processing of uplink analog signals received from the substation device. In the transmission process, downlink signal processing is performed to reflect the selection result of the substation device in the transmission process. In the receiving process, uplink signal processing is performed to reflect the selection result of the substation device in the receiving process.

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