WO2016136188A1 - Optical fiber wireless access system, central station device, base station device, extraction method and communication method - Google Patents

Optical fiber wireless access system, central station device, base station device, extraction method and communication method Download PDF

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Publication number
WO2016136188A1
WO2016136188A1 PCT/JP2016/000805 JP2016000805W WO2016136188A1 WO 2016136188 A1 WO2016136188 A1 WO 2016136188A1 JP 2016000805 W JP2016000805 W JP 2016000805W WO 2016136188 A1 WO2016136188 A1 WO 2016136188A1
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Prior art keywords
signal
downlink
optical
multiplexed
radio signal
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PCT/JP2016/000805
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French (fr)
Japanese (ja)
Inventor
知行 山瀬
真一 堀
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日本電気株式会社
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Priority to JP2017501899A priority Critical patent/JPWO2016136188A1/en
Publication of WO2016136188A1 publication Critical patent/WO2016136188A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/54—Intensity modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/02—Channels characterised by the type of signal
    • H04L5/04—Channels characterised by the type of signal the signals being represented by different amplitudes or polarities, e.g. quadriplex

Definitions

  • the present invention relates to an optical fiber radio access system, a central station apparatus, a base station apparatus, an extraction method and a communication method, and more particularly to an optical fiber radio access system, a central station apparatus, a base station apparatus, an extraction method and a communication method for performing intensity modulation.
  • small cells can be formed on a small scale compared to conventional macro cells, and small-sized cells can be accommodated with high efficiency by deploying cells formed on a small scale in existing macro cells.
  • Cell networks are being considered.
  • a base station unit (BBU), a radio frequency (RF) circuit, and an RRU (remote radio unit) including an antenna are geographically and functionally separated to transmit and receive from the antenna.
  • the RRU responsible for the function is downsized, and the RRU is spatially densely deployed.
  • it is considered to use optical communication excellent in high capacity and high speed signal transmission for communication between them.
  • a RoF (Radio over Fiber) technique for transmitting a radio signal via an optical transmission line is used.
  • the transmission distance and the transmission rate can be dramatically increased, and a plurality of RRUs in the macro cell can be aggregated using one BBU.
  • the RRU is required to be configured with lower power and smaller size from the viewpoint of ease of installation.
  • an external modulation system which is one of the systems used to modulate light using an electrical signal
  • a laser that supplies CW (continuous wave) light to the optical modulator and its temperature control consume a great amount of power. Cost. Therefore, in order to simplify the RRU and save power, it has been studied to exclude the light source and the mechanism for controlling the light source from the RRU.
  • a means for supplying an unmodulated optical signal necessary for an optical modulator constituting the RRU from a light source constituting the BBU in order to perform electrical-optical conversion of the uplink signal in the RRU is known.
  • Patent Document 1 discloses a configuration of an optical fiber wireless access system having a center station and an antenna station.
  • the antenna station is not provided with a semiconductor laser (light source).
  • the antenna station superimposes the downlink radio signal and optically modulates the optical wave transmitted from the center station using the uplink radio signal.
  • the center station extracts only the uplink optical signal from the optical wave optically modulated using the uplink radio signal using a band transmission filter. By configuring in this way, the antenna station can superimpose the uplink radio signal on the light without providing a light source in its own apparatus.
  • Patent Document 2 discloses a configuration of an optical fiber network system having a center station device (telephone station) and a slave station device (user device).
  • the antenna station frequency-multiplexes uplink signals and downlink signals having different frequencies. Therefore, it is necessary to arrange a frequency filter for separating signals in the center station, which causes a problem that the system becomes complicated. Furthermore, by performing frequency multiplexing, signals may interfere with each other, resulting in errors in the signals.
  • the technique of Patent Document 2 does not solve this problem.
  • the main object of the present invention is to provide an optical fiber radio access system, a central station apparatus, a base station apparatus, an extraction method, and a communication method capable of separating an uplink signal and a downlink signal without using a frequency filter.
  • An optical fiber radio access system is an optical fiber radio access system in which a central station apparatus and a base station apparatus are connected by first and second optical fibers, the central station apparatus A first photoelectric conversion unit that converts the downlink radio signal into a downlink optical signal by intensity-modulating the optical signal output from the light source using the downlink radio signal; and the first light A light receiving unit for receiving, via the second optical fiber, a multiplexed optical signal generated by intensity-modulating the downlink optical signal transmitted to the base station device via a fiber; and the multiplexed light And an extraction unit that extracts the uplink radio signal from a signal, wherein the base station device transmits the dashes transmitted from the central station device via the first optical fiber.
  • intensity modulation using a Nrinku optical signal the uplink radio signal, in which and a multiplexing unit for generating the multiplexed optical signal obtained by multiplexing said downlink radio signal and the uplink radio signal.
  • a central station apparatus is a central station apparatus connected to a base station apparatus by first and second optical fibers, and converts an optical signal output from a light source into a downlink radio signal.
  • a first photoelectric conversion unit that converts the downlink radio signal into a downlink optical signal by intensity modulation using the downlink, and the downlink transmitted to the base station apparatus via the first optical fiber.
  • a base station apparatus is a base station apparatus connected to a central station apparatus through first and second optical fibers, and the central station passes through the first optical fiber.
  • a multiplexed optical signal obtained by multiplexing the uplink radio signal and the downlink radio signal included in the downlink optical signal by intensity-modulating the downlink optical signal transmitted from the apparatus using the uplink radio signal.
  • the multiplexed optical signal is generated and transmitted to the central station apparatus via a second optical fiber.
  • An extraction method is a signal extraction method used in a central station apparatus connected to a base station apparatus through first and second optical fibers, and an optical signal output from a light source is obtained.
  • the downlink radio signal is converted into a downlink optical signal by intensity modulation using a downlink radio signal, and the downlink optical signal transmitted to the base station apparatus via the first optical fiber is converted into the downlink optical signal.
  • the uplink radio signal is extracted from the multiplexed optical signal.
  • a communication method is a communication method used in a base station apparatus connected to a central station apparatus through first and second optical fibers, and is routed through the first optical fiber.
  • the uplink radio signal and the downlink radio signal included in the downlink optical signal are multiplexed by intensity-modulating the downlink optical signal transmitted from the central station apparatus using the uplink radio signal.
  • a multiplexed optical signal is generated, and the multiplexed optical signal is transmitted to the central station apparatus via a second optical fiber.
  • a recording medium is a program for causing a computer connected to a base station apparatus through first and second optical fibers to execute an optical signal output from a light source as a downlink radio signal.
  • the downlink radio signal is converted into a downlink optical signal by intensity modulation using the base station, and the downlink optical signal transmitted to the base station apparatus via the first optical fiber is converted into the base station.
  • a non-transitory computer readable recording medium for recording a program for causing a computer to extract the uplink radio signal from the computer That.
  • an optical fiber radio access system a central station apparatus, a base station apparatus, an extraction method, and a communication method that can separate an uplink signal and a downlink signal without using a frequency filter.
  • FIG. 1 is a configuration diagram of an optical fiber wireless access system according to a first embodiment.
  • FIG. 3 is a configuration diagram of an optical fiber wireless access system according to a second embodiment. It is a figure which shows the flow of the signal processing in BBU concerning Embodiment 2.
  • FIG. It is a figure which shows the flow of the signal processing in RRU concerning Embodiment 2.
  • FIG. 6 is a configuration diagram of an optical fiber wireless access system according to a third embodiment. It is a time chart of the downlink electric signal concerning Embodiment 3.
  • 10 is a time chart of a downlink optical signal according to the third embodiment.
  • 10 is a time chart of uplink electrical signals according to the third exemplary embodiment.
  • FIG. 6 is a configuration diagram of an optical fiber wireless access system according to a fourth embodiment.
  • 10 is a time chart of electric signals according to the fourth embodiment. It is a time chart of the uplink electric signal concerning Embodiment 4.
  • 10 is a time chart of a downlink / uplink multiplexed electrical signal according to the fourth embodiment.
  • FIG. 10 is a time chart of a downlink / uplink multiplexed optical signal according to the fourth embodiment; It is a time chart of the uplink electric signal concerning Embodiment 4.
  • FIG. 10 is a configuration diagram of an optical fiber wireless access system according to a fifth embodiment.
  • FIG. 10 is a configuration diagram of an optical fiber wireless access system according to a sixth embodiment.
  • the optical fiber radio access system in FIG. 1 includes a central station device 100 and a base station device 110.
  • Central station apparatus 100 is connected to base station apparatus 110 by optical fiber 120 and optical fiber 130.
  • the central station apparatus 100 includes a photoelectric conversion unit 101, a light receiving unit 102, and an extraction unit 103.
  • the photoelectric conversion unit 101 converts the downlink radio signal into the downlink optical signal by intensity-modulating the optical signal output from the light source using the downlink radio signal.
  • the light source may be a laser, for example.
  • the optical signal may be CW (ContinuoustinWave) light output from the laser.
  • the downlink radio signal may be an electrical signal.
  • a downlink radio signal is a signal transmitted to a communication terminal device such as a mobile phone or a smartphone via the base station device 110.
  • the photoelectric conversion unit 101 transmits a downlink radio signal to the base station apparatus 110 via the optical fiber 120.
  • the light receiving unit 102 receives the multiplexed optical signal generated by the intensity modulation of the downlink optical signal via the optical fiber 130.
  • the multiplexed optical signal is generated in the base station device 110.
  • the extraction unit 103 extracts an uplink radio signal from the multiplexed optical signal received by the light receiving unit 102.
  • the uplink radio signal is a signal transmitted from the communication terminal apparatus to the central station apparatus 100 via the base station apparatus 110.
  • Base station apparatus 110 has multiplexing section 111.
  • the multiplexing unit 111 modulates the intensity of the downlink optical signal transmitted from the central station apparatus 100 via the optical fiber 120 using the uplink radio signal.
  • the multiplexing unit 111 generates a multiplexed optical signal obtained by multiplexing the uplink radio signal and the downlink radio signal.
  • the multiplexing unit 111 transmits the multiplexed optical signal to the central station apparatus 100 via the optical fiber 130.
  • the base station apparatus 110 in the optical fiber radio access system of FIG. 1 can multiplex the uplink radio signal and the downlink radio signal by intensity-modulating the downlink optical signal. Therefore, the central station device 100 does not need to use a frequency filter when extracting the uplink radio signal from the multiplexed optical signal, so that the system can be configured simply. Furthermore, by performing the intensity multiplexing of the optical signal, it is possible to prevent an event in which the signals generated when the frequency multiplexing is performed interfere with each other.
  • FIG. 2 is a configuration diagram of an optical fiber wireless access system according to the second embodiment.
  • the optical fiber radio access system shown in FIG. 2 has a BBU (or baseband processing unit) 1 and an RRU (remote radio unit) 2.
  • BBU1 and RRU2 are connected by optical transmission lines 7 and 8 using optical fibers.
  • the BBU 1 includes a transmission / reception unit (TRX) 3, a light source (laser diode: LD) 4, an optical modulator (MOD) 5, and a light receiver (PD) 10.
  • the RRU 2 includes an optical coupler 13, a light receiver (PD) 9, a band pass filter 21, a duplexer 11, an amplifier 26, and an optical modulator 6.
  • the antenna 12 transmits the downlink electrical signal output from the RRU 2 as the transmission signal 12a.
  • the antenna 12 outputs the received reception signal 12b to the RRU 2 as an uplink electrical signal.
  • the downlink electrical signal 3a is subjected to pulse width modulation or pulse position modulation by the transmission / reception unit 3 of the BBU1.
  • the downlink electrical signal 3 a is a signal in the 1-bit digital signal format of the RF band output from the transmission / reception unit 3.
  • the downlink electrical signal 3a is input to the optical modulator 5 as a drive signal.
  • the light source 4 makes the generated CW light enter the optical modulator 5.
  • the optical modulator 5 intensity-modulates the CW light using the downlink electrical signal 3a, and converts the downlink electrical signal 3a into the downlink optical signal 7a.
  • the optical signal 3a When the downlink electrical signal 3a is converted into an optical signal by the optical modulator 5, the optical signal is modulated so that the optical signal does not turn off or does not become the minimum intensity with respect to the maximum intensity of the incident CW light.
  • the downlink electrical signal 3a For the voltage level and amplitude.
  • the downlink electrical signal 3a is set to a voltage level and amplitude for performing optical intensity modulation so that the converted optical signal includes an optical intensity offset.
  • the optical modulator 5 converts the downlink electrical signal 3a into the downlink optical signal 7a, and transmits the downlink optical signal 7a to the RRU 2 via the optical transmission line 7.
  • the optical coupler 13 branches the downlink optical signal 7a transmitted from the BBU 1 and including the optical intensity offset into two systems of downlink optical signals 13a and 13b.
  • the optical coupler 13 outputs one of the branched downlink optical signals 13 a to the light receiver 9.
  • the optical receiver 9 converts the downlink optical signal 13a into an electric signal 9a by performing photoelectric conversion.
  • the light receiver 9 outputs the electric signal 9a to the band-pass filter 21 that passes only the fundamental frequency component.
  • the band pass filter 21 outputs a downlink electrical signal 11 a having only the fundamental frequency component of the electrical signal 9 a to the terminal A of the duplexer 11.
  • the duplexer 11 supplies the downlink electrical signal 11 a from the terminal B to the antenna 12. That is, the antenna 12 is driven by the downlink electrical signal 11a and transmits the transmission signal 12a.
  • the antenna 12 supplies the received reception signal 12b to the terminal B of the duplexer 11.
  • the duplexer 11 supplies the output from the antenna 12, that is, the uplink electrical signal 11b, from the terminal C to the amplifier 26.
  • the amplifier 26 converts the uplink electrical signal 11b into an electrical signal having an appropriate voltage offset level and amplitude.
  • the amplifier 26 converts the uplink electrical signal 11b into an electrical signal having an appropriate voltage offset level and amplitude, and outputs the converted uplink electrical signal 26a to the optical modulator 6.
  • the uplink electrical signal 26 a is input to the optical modulator 6 as a modulation signal of the optical modulator 6.
  • the optical coupler 13 supplies the other branched downlink optical signal 13 b to the optical modulator 6.
  • the optical modulator 6 intensity-modulates the downlink optical signal 7a having an offset with respect to the optical intensity by using the uplink electrical signal 26a that is a drive signal, and the uplink electrical signal 26a is downlink / uplink multiplexed light. Convert to signal 8a.
  • the downlink / uplink multiplexed optical signal 8a is a signal obtained by superimposing the downlink electrical signal 3a and the uplink electrical signal 26a in the signal strength of the optical signal region.
  • the optical modulator 6 further modulates the downlink optical signal 13b using the uplink electrical signal 26a in order to superimpose the uplink electrical signal 26a on the downlink electrical signal 3a.
  • the optical modulator 6 transmits the downlink / uplink multiplexed optical signal 8 a to the BBU 1 through the optical transmission line 8.
  • the optical receiver 10 converts the downlink / uplink multiplexed optical signal 8a transmitted from the RRU 2 into a downlink / uplink multiplexed electrical signal 10a.
  • the light receiver 10 outputs a downlink / uplink multiplexed electrical signal 10 a to the transmission / reception unit 3.
  • the transmission / reception unit 3 extracts the uplink signal by subtracting the downlink electrical signal 3a from the downlink / uplink multiplexed electrical signal 10a by digital signal processing.
  • the optical modulator 5 intensity-modulates the CW light generated in the light source 4 using the downlink electrical signal 3a as a drive signal (S11).
  • the optical modulator 5 transmits the CW light intensity-modulated by the downlink electrical signal 3a as the downlink optical signal 7a to the RRU 2 via the optical transmission line 7 (S12).
  • the optical modulator 5 converts the downlink electrical signal 3a into the downlink optical signal 7a, and transmits the downlink optical signal 7a to the RRU 2.
  • the optical receiver 10 receives the downlink / uplink multiplexed optical signal 8a transmitted from the RRU 2 (S13).
  • the optical receiver 10 converts the downlink / uplink multiplexed optical signal 8a into a downlink / uplink multiplexed electrical signal 10a by photoelectric conversion (S14).
  • the transmitting / receiving unit 3 extracts the uplink electrical signal by subtracting the downlink electrical signal 4a from the downlink / uplink multiplexed electrical signal 10a (S15).
  • the optical coupler 13 receives the downlink optical signal 7a via the optical transmission line 7 (S21).
  • the optical coupler 13 branches the downlink optical signal 7a and outputs one downlink optical signal 13b to the optical modulator 6 (S22).
  • the optical modulator 6 receives the downlink optical signal 13b by using the uplink electrical signal 26a received by the antenna 12 and converted by the amplifier 26 into an electrical signal having an appropriate voltage offset level and amplitude as a drive signal.
  • the intensity is modulated (S23).
  • the optical modulator 6 transmits the downlink optical signal 13b intensity-modulated by the uplink electrical signal 26a as the downlink / uplink multiplexed optical signal 8a to the BBU 1 via the optical transmission line 8 (S24). ).
  • both uplink and downlink optical fiber radio communications can be realized without arranging a light source in the RRU 2. Can do. Further, the optical modulator 5 of the BBU1 and the optical modulator 6 of the RRU2 intensity-modulate the optical signal using the electric signal. Therefore, the configuration of the BBU 1 is simplified because it is not necessary to use a frequency filter when demodulating an intensity-modulated optical signal.
  • the BBU 1 in FIG. 5 has a comparator 22 added to the BBU 1 in FIG.
  • the other configuration of BBU1 in FIG. 5 is the same as that of BBU1 in FIG.
  • the amplifier 26 in the RRU 2 in FIG. 2 is replaced with a data conversion circuit 25.
  • the other configuration of the RRU 2 in FIG. 5 is the same as that of the RRU 2 in FIG.
  • the comparator 22 operates according to a threshold value for extracting the 1-bit digital signal of the uplink electrical signal from the downlink / uplink multiplexed electrical signal 10a.
  • the comparator 22 outputs the extracted signal to the transmission / reception unit 3 as an uplink electrical signal 22a.
  • the data conversion circuit 25 converts the received signal into a 1-bit digital format uplink electrical signal 25a in the RF band by performing pulse modulation such as pulse width modulation or pulse position modulation.
  • FIGS. 6 to 11 including time charts of electric signals or optical signals at respective main points in the third embodiment.
  • the downlink electrical signal 3a shown in FIG. 6 is a signal in the RF band 1-bit digital signal format that is pulse width modulated or pulse position modulated by the transceiver 3 of the BBU1.
  • the vertical axis represents the voltage level
  • the horizontal axis represents time.
  • Downlink electrical signal 3 a transitions between voltage level 2 and voltage level 3. That is, the downlink electrical signal 3a has an offset from voltage level 0 to voltage level 2.
  • the downlink optical signal 7a shown in FIG. 7 is a signal obtained by intensity-modulating the CW light generated by the light source 4 with the downlink electrical signal 3a in the optical modulator 5.
  • the vertical axis indicates the light intensity
  • the horizontal axis indicates time.
  • the downlink optical signal 7 a transitions between the light intensity 2 and the light intensity 3.
  • the downlink optical signal 7a has an offset from light intensity 0 to light intensity 2.
  • the downlink optical signal 7a has a waveform similar to that of the downlink electrical signal because the unmodulated CW light is intensity-modulated using the downlink electrical signal 3a.
  • the uplink electrical signal 25a shown in FIG. 8 is a signal obtained by converting the reception signal received by the antenna in the data conversion circuit 25.
  • the vertical axis indicates the voltage level
  • the horizontal axis indicates time.
  • Uplink electrical signal 25a transitions between voltage level 0 and voltage level 3. That is, the uplink electrical signal 25a does not have an offset like the downlink electrical signal 3a.
  • the downlink / uplink multiplexed optical signal shown in FIG. 9 is a signal obtained by intensity-modulating the downlink optical signal 13b in the optical modulator 6 with the uplink electrical signal 25a.
  • the vertical axis indicates the light intensity
  • the horizontal axis indicates time.
  • the downlink / uplink multiplexed optical signal 8 a transitions between light intensity 0 and light intensity 3.
  • the downlink electrical signal 3a is multiplexed with the uplink electrical signal 25a.
  • the uplink electrical signal 25a modulates the downlink optical signal 7a using the offset of the downlink optical signal 7a having an offset with respect to the optical intensity.
  • the optical modulator 6 performs intensity modulation with a drive voltage sufficient to turn off the downlink optical signal 7a in order to superimpose the uplink electrical signal 25a on the downlink optical signal 7a.
  • a downlink / uplink multiplexed electrical signal 10a shown in FIG. 10 is an electrical signal converted from the downlink optical signal 7a in the optical receiver 10.
  • the vertical axis indicates the voltage level, and the horizontal axis indicates time.
  • the downlink / uplink multiplexed electrical signal 10a shows a waveform similar to that of the downlink / uplink multiplexed optical signal 8a.
  • the comparator 22 outputs, for example, a period in which the voltage level of the downlink / uplink multiplexed electric signal 10a is higher than 1 with the voltage level 1 as a threshold, and the voltage level of the downlink / uplink multiplexed electric signal 10a is A period of 1 or less is output as an L level.
  • the uplink electrical signal 22a in FIG. 11 shows the same waveform as the uplink electrical signal 25a in FIG. That is, the comparator 22 extracts the uplink electrical signal 25a from the downlink / uplink multiplexed electrical signal 10a.
  • the optical fiber radio access system according to the third exemplary embodiment of the present invention is similar to the case of using the optical fiber radio access system of FIG. It is possible to realize both-fiber optical fiber communication in the downlink. Further, the optical modulator 5 of the BBU1 and the optical modulator 6 of the RRU2 intensity-modulate the optical signal using the electric signal. Therefore, the configuration of the BBU 1 is simplified because it is not necessary to use a frequency filter when demodulating an intensity-modulated optical signal.
  • the subtracter 24 receives the electric signal 9a output from the light receiver 9 and one of the two branched signals.
  • the subtractor 24 subtracts the electrical signal 9a from the uplink electrical signal 25a output from the data conversion circuit 25 in the voltage domain.
  • Subtracting in the voltage domain means subtracting the voltage level indicated by the electrical signal 9a from the voltage level indicated by the uplink electrical signal 25a.
  • the subtractor 24 outputs a downlink / uplink multiplexed electrical signal 24a, which is a result of subtracting the electrical signal 9a from the uplink electrical signal 25a, to the optical modulator 6.
  • FIGS. 13 to 17 including time charts of electric signals or optical signals at respective main points in the fourth embodiment.
  • the electrical signal 9a in FIG. 13 is the electrical signal 9a output from the light receiver 9, and shows one of the electrical signals branched into two systems.
  • the electrical signal 9a is an electrical signal converted from the downlink optical signal 7a, and transits between the voltage level 0 and the voltage level 1.
  • the electrical signal 9a has the same waveform as the downlink optical signal 7a, although the offset position is different.
  • the uplink electrical signal 25a shown in FIG. 14 is a signal obtained by converting the received signal received by the antenna in the data conversion circuit 25.
  • the vertical axis indicates the voltage level and the horizontal axis indicates time.
  • Uplink electrical signal 25a transitions between voltage level 1 and voltage level 3. That is, the uplink electrical signal 25a has an offset from voltage level 0 to voltage level 1.
  • the downlink / uplink multiplexed electrical signal 24a shown in FIG. 15 shows a waveform after the electrical signal 9a shown in FIG. 13 is subtracted in the voltage domain from the uplink electrical signal 25a shown in FIG.
  • the downlink / uplink multiplexed optical signal 8b shown in FIG. 16 is a signal that has been intensity-modulated by the optical modulator 6 using the downlink / uplink multiplexed electrical signal 24a.
  • the downlink / uplink multiplexed electrical signal 24a is a signal obtained by subtracting the electrical signal 9a indicating the downlink electrical signal from the uplink electrical signal 25a.
  • the downlink / uplink multiplexed optical signal 8b is a signal obtained by superimposing the downlink / uplink multiplexed electrical signal 24a and the downlink electrical signal 3a in the signal strength of the optical signal region. Therefore, the downlink / uplink multiplexed optical signal 8b cancels out the optical intensity corresponding to the downlink optical signal 7a, and shows a waveform similar to that of the uplink electrical signal 25a.
  • the uplink electrical signal 10b in FIG. 17 is an electrical signal converted from the downlink / uplink multiplexed optical signal 8b in the optical receiver 10.
  • Uplink electrical signal 10b shows a waveform similar to uplink electrical signal 25a.
  • the optical fiber radio access system according to the fourth exemplary embodiment of the present invention is the same as when the optical fiber radio access system according to the second and third exemplary embodiments is used, without arranging a light source in the RRU 2.
  • Both uplink and downlink optical fiber radio communication can be realized.
  • the RRU 2 can generate a downlink / uplink multiplexed optical signal including only the uplink electrical signal 25a in the optical modulator 6 by using the subtractor 24. Therefore, the light receiver 10 of the BBU 1 can generate the uplink electrical signal 10b that does not include the downlink electrical signal. Thereby, the process in BBU1 can be reduced.
  • the subtracter 24 subtracts the electrical signal 9a from the uplink electrical signal 11b amplified by the amplifier 26.
  • the subtractor 24 outputs a downlink / uplink multiplexed electric signal 24a, which is a subtraction result, to the optical modulator 6.
  • the downlink / uplink multiplexed electrical signal 24a has the same waveform as the downlink / uplink multiplexed electrical signal 24a of FIG. Therefore, the optical receiver 10 of BBU1 can extract the uplink electrical signal 10b similar to the uplink electrical signal 10b of FIG.
  • the optical fiber radio access system according to the fifth embodiment of the present invention is the same as when using the optical fiber radio access system according to the second to fourth embodiments without arranging a light source in the RRU 2. Both uplink and downlink optical fiber radio communication can be realized. Further, the BBU 1 does not need to perform processing for removing the downlink electrical signal from the downlink / uplink multiplexed optical signal. Therefore, the processing burden on BBU1 can be reduced.
  • the optical receiver 10 receives the downlink / uplink multiplexed optical signal 8a as in the operation in FIG. Furthermore, the optical receiver 10 converts the downlink / uplink multiplexed optical signal 8a into a downlink / uplink multiplexed electrical signal 10a. The light receiver 10 outputs a downlink / uplink multiplexed electrical signal 10 a to the subtractor 28.
  • the subtracter 28 subtracts the downlink electrical signal 27a from the downlink / uplink multiplexed electrical signal 10a in the voltage domain.
  • the downlink electrical signal 27a is an electrical signal obtained by adding a delay in the delay circuit 27 to one downlink electrical signal 3a of the downlink electrical signal 3a branched into two systems.
  • the delay circuit 27 adjusts the timing for outputting the downlink electrical signal 3a so that the downlink electrical signal 3a can be subtracted from the downlink / uplink multiplexed electrical signal 10a. That is, the delay circuit 27 takes into account the processing delay in the optical modulator 5, the optical coupler 13, the optical modulator 6, and the light receiver 10, and further the transmission delay in the optical transmission path 7 and the optical transmission path 8. The timing for outputting the signal 27a may be adjusted.
  • the subtractor 28 subtracts the downlink electrical signal 27a from the downlink / uplink multiplexed electrical signal 10a in the voltage domain, and outputs the uplink electrical signal 28a from which the downlink electrical signal 3a has been removed to the transceiver unit 3. be able to.
  • the optical fiber radio access system according to the sixth embodiment of the present invention is the same as when using the optical fiber radio access system according to the second to fifth embodiments, without arranging a light source in the RRU 2. Both uplink and downlink optical fiber radio communication can be realized. Further, the BBU 1 does not need to use a frequency filter with a high processing load by using the subtractor 28.
  • the present invention has been described as a hardware configuration, but the present invention is not limited to this.
  • the present invention can also realize the processing in BBU1 and RRU2 by causing a CPU (Central Processing Unit) to execute a computer program.
  • a CPU Central Processing Unit
  • Non-transitory computer readable media include various types of tangible storage media.
  • Examples of non-transitory computer-readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD (Compact Disc) -ROM (Read Only Memory), CD-R (Recordable), CD-R / W (ReWritable), semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)).
  • the program may also be supplied to the computer by various types of transitory computer readable media.
  • Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves.
  • the temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.
  • the central station apparatus converts an optical signal output from a light source into a downlink radio signal.
  • the first photoelectric conversion means for converting the downlink radio signal into a downlink optical signal by performing intensity modulation using the signal, and the downlink transmitted to the base station apparatus via the first optical fiber.
  • a light receiving means for receiving a multiplexed optical signal generated by intensity-modulating the link optical signal via the second optical fiber; an extracting means for extracting the uplink radio signal from the multiplexed optical signal;
  • the base station apparatus uses the downlink radio signal transmitted from the central station apparatus via the first optical fiber as the uplink radio signal.
  • the central station apparatus further includes second photoelectric conversion means for converting the multiplexed optical signal into a multiplexed radio signal, and the extraction means uses the comparator circuit to improve the up-conversion from the multiplexed radio signal.
  • the optical fiber radio access system according to appendix 1, which extracts a link radio signal.
  • the central station apparatus further includes second photoelectric conversion means for converting the multiplexed optical signal into a multiplexed wireless signal, and the extracting means uses the subtracting circuit to reduce the downlink from the multiplexed wireless signal.
  • the optical fiber radio access system according to appendix 1, wherein the uplink radio signal is extracted by subtracting a radio signal.
  • the central station device converts an optical signal output from a light source into a downlink radio signal.
  • the first photoelectric conversion means for converting the downlink radio signal into a downlink optical signal by performing intensity modulation using the signal, and the downlink transmitted to the base station apparatus via the first optical fiber.
  • Light receiving means for receiving a multiplexed optical signal generated by intensity-modulating a link optical signal via the second optical fiber, and the base station device passes through the first optical fiber.
  • first multiplexing means for generating a multiplexed radio signal by subtracting the uplink radio signal from the downlink radio signal output from the second photoelectric conversion means; And a second multiplexing means for generating the multiplexed optical signal by intensity-modulating the downlink optical signal using the multiplexed wireless signal.
  • the said 1st photoelectric conversion means uses the said downlink radio signal by which the voltage level and the amplitude were set so that it might be converted into the said downlink optical signal containing predetermined
  • a central station apparatus connected to a base station apparatus through first and second optical fibers, wherein the optical signal output from the light source is intensity-modulated using a downlink radio signal, whereby the down A first photoelectric conversion means for converting a link radio signal into a downlink optical signal; and the downlink optical signal transmitted to the base station device via the first optical fiber is uploaded in the base station device.
  • a central station apparatus comprising: extraction means for extracting the uplink radio signal from a multiplexed optical signal obtained by intensity modulation using a link radio signal and multiplexing the uplink radio signal and the downlink radio signal.
  • a downlink optical signal transmitted from the central station apparatus via the first optical fiber which is a base station apparatus connected to the central station apparatus via the first and second optical fibers.
  • the optical signal output from a light source is intensity-modulated using a downlink radio signal
  • the optical signal output from a light source is intensity-modulated using a downlink radio signal
  • a multiplexed optical signal that is intensity-modulated using a signal and multiplexed with the uplink radio signal and the downlink radio signal is received via the second optical fiber, and the uplink radio signal is received from the multiplexed optical signal.
  • the downlink radio signal is converted into a downlink optical signal and transmitted to the base station apparatus via the first optical fiber, and the downlink optical signal is transmitted using the uplink radio signal in the base station apparatus.
  • a non-transitory computer-readable recording medium that records a program that causes a computer to execute the above-described process.
  • a downlink program which is executed by a computer connected to a central office device via first and second optical fibers, transmitted from the central office device via the first optical fiber
  • An optical signal is intensity-modulated using an uplink radio signal to generate a multiplexed optical signal in which the uplink radio signal and the downlink radio signal included in the downlink optical signal are multiplexed, and the multiplexed optical signal is
  • a non-transitory computer-readable recording medium for recording a program for causing a computer to execute transmission to the central office device via a second optical fiber.

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Abstract

In order to provide an optical fiber wireless access system capable of separating an uplink signal and a downlink signal without using a frequency filter, this optical fiber wireless access system comprises a central station device 100 and a base station device 110 that are connected by an optical fiber. The central base station 100 is provided with a photoelectric conversion unit 101 that converts a downlink wireless signal into a downlink optical signal by intensity modulation, a light receiving unit 102 that receives a multiple optical signal generated by intensity modulating the downlink optical signal transmitted to the base station device 110, and an extraction unit 103 that extracts an uplink wireless signal. The base station device 110 is provided with a multiplexing unit 111 that generates the multiple optical signal by intensity modulating the downlink optical signal transmitted from the central station device 100 using the uplink wireless signal.

Description

光ファイバ無線アクセスシステム、中央局装置、基地局装置、抽出方法及び通信方法Optical fiber radio access system, central station apparatus, base station apparatus, extraction method and communication method
　本発明は光ファイバ無線アクセスシステム、中央局装置、基地局装置、抽出方法及び通信方法に関し、特に強度変調を行う光ファイバ無線アクセスシステム、中央局装置、基地局装置、抽出方法及び通信方法に関する。 The present invention relates to an optical fiber radio access system, a central station apparatus, a base station apparatus, an extraction method and a communication method, and more particularly to an optical fiber radio access system, a central station apparatus, a base station apparatus, an extraction method and a communication method for performing intensity modulation.
　モバイルネットワークのアクセス網において、従来のマクロセルと比較し小規模にセル形成し、小規模に形成されたセルを、既存のマクロセル内に高密度に展開することによって高効率にモバイルデータを収容するスモールセルネットワークが検討されている。スモールセルネットワークでは、基地局を構成するＢＢＵ（Ｂａｓｅ　Ｂａｎｄ　Ｕｎｉｔ）、ＲＦ（Ｒａｄｉｏ　Ｆｒｅｑｕｅｎｃｙ）回路及びアンテナを含むＲＲＵ（Ｒｅｍｏｔｅ　Ｒａｄｉｏ　Ｕｎｉｔ）が地理的、機能的に分離されることによって、アンテナからの送受信機能を担うＲＲＵが小型化され、ＲＲＵが空間的に高密度に展開される。
ＢＢＵ－ＲＲＵ間を分離するため、その間の通信には大容量かつ高速信号伝送に優れた光通信を用いることが検討されている。そのため、ＢＢＵ－ＲＲＵ間については光伝送路を介して無線信号を伝送するＲｏＦ（Ｒａｄｉｏ　ｏｖｅｒ　Ｆｉｂｅｒ）技術が用いられる。ＲｏＦ技術を利用することで、伝送距離や伝送レートが飛躍的に拡大でき、マクロセル内の複数のＲＲＵを１つのＢＢＵを用いて集約できる。そうした中で、設置の容易性の観点からＲＲＵはより低電力かつ小型に構成することが要求される。 In mobile network access networks, small cells can be formed on a small scale compared to conventional macro cells, and small-sized cells can be accommodated with high efficiency by deploying cells formed on a small scale in existing macro cells. Cell networks are being considered. In a small cell network, a base station unit (BBU), a radio frequency (RF) circuit, and an RRU (remote radio unit) including an antenna are geographically and functionally separated to transmit and receive from the antenna. The RRU responsible for the function is downsized, and the RRU is spatially densely deployed.
In order to separate between BBU and RRU, it is considered to use optical communication excellent in high capacity and high speed signal transmission for communication between them. For this reason, between the BBU and RRU, a RoF (Radio over Fiber) technique for transmitting a radio signal via an optical transmission line is used. By using the RoF technology, the transmission distance and the transmission rate can be dramatically increased, and a plurality of RRUs in the macro cell can be aggregated using one BBU. Under such circumstances, the RRU is required to be configured with lower power and smaller size from the viewpoint of ease of installation.
　しかしながら、電気信号を用いて光を変調する場合に用いられる方式の一つである外部変調方式において、光変調器にＣＷ（ｃｏｎｔｉｎｕｏｕｓ　ｗａｖｅ）光を供給するレーザーやその温度制御は多大な電力消費を要する。そこで、ＲＲＵの簡素化、省電力化するために、光源およびそれを制御するための機構をＲＲＵから排除することが検討されている。具体的には、ＲＲＵにおいてアップリンク信号を電気―光変換するため、ＲＲＵを構成する光変調器において必要な無変調の光信号を、ＢＢＵを構成する光源より供給する手段が知られている。 However, in an external modulation system, which is one of the systems used to modulate light using an electrical signal, a laser that supplies CW (continuous wave) light to the optical modulator and its temperature control consume a great amount of power. Cost. Therefore, in order to simplify the RRU and save power, it has been studied to exclude the light source and the mechanism for controlling the light source from the RRU. Specifically, a means for supplying an unmodulated optical signal necessary for an optical modulator constituting the RRU from a light source constituting the BBU in order to perform electrical-optical conversion of the uplink signal in the RRU is known.
　特許文献１には、センタ局とアンテナ局とを有する光ファイバ無線アクセスシステムの構成が開示されている。具体的には、アンテナ局は、半導体レーザー（光源）を設けていない。アンテナ局は、ダウンリンク用無線信号が重畳され、センタ局から送信された光波を、アップリンク用無線信号を用いて光変調する。さらに、センタ局は、アップリンク用無線信号を用いて光変調された光波から、帯域透過フィルタを用いてアップリンク用の光信号のみを抽出する。このように構成することによって、アンテナ局は、自装置内に光源を設けずに、アップリンク用無線信号を光に重畳することができる。
　特許文献２には、センタ局装置（電話局）と子局装置（ユーザ装置）とを有する光ファイバネットワークシステムの構成が開示されている。 Patent Document 1 discloses a configuration of an optical fiber wireless access system having a center station and an antenna station. Specifically, the antenna station is not provided with a semiconductor laser (light source). The antenna station superimposes the downlink radio signal and optically modulates the optical wave transmitted from the center station using the uplink radio signal. Further, the center station extracts only the uplink optical signal from the optical wave optically modulated using the uplink radio signal using a band transmission filter. By configuring in this way, the antenna station can superimpose the uplink radio signal on the light without providing a light source in its own apparatus.
Patent Document 2 discloses a configuration of an optical fiber network system having a center station device (telephone station) and a slave station device (user device).
特開２００２－１４１８７１号公報JP 2002-141871 A 特開平１１－１５４９１５号公報JP-A-11-154915
　しかし、特許文献１における光ファイバ無線アクセスシステムにおいては、アンテナ局が、異なる周波数を有するアップリンク信号及びダウンリンク信号を周波数多重している。そのため、センタ局に、信号を分離するための周波数フィルタを配置する必要があり、システムが複雑化するという問題がある。さらに、周波数多重を行うことによって、信号同士が干渉しあい、その結果、信号にエラーが生じる可能性もある。特許文献２の技術もこの課題を解決するものではない。 However, in the optical fiber wireless access system in Patent Document 1, the antenna station frequency-multiplexes uplink signals and downlink signals having different frequencies. Therefore, it is necessary to arrange a frequency filter for separating signals in the center station, which causes a problem that the system becomes complicated. Furthermore, by performing frequency multiplexing, signals may interfere with each other, resulting in errors in the signals. The technique of Patent Document 2 does not solve this problem.
　本発明は、周波数フィルタを用いることなくアップリンク信号及びダウンリンク信号を分離することができる光ファイバ無線アクセスシステム、中央局装置、基地局装置、抽出方法及び通信方法を提供することを主な目的とする。 The main object of the present invention is to provide an optical fiber radio access system, a central station apparatus, a base station apparatus, an extraction method, and a communication method capable of separating an uplink signal and a downlink signal without using a frequency filter. And
　本発明の第１の態様にかかる光ファイバ無線アクセスシステムは、中央局装置と基地局装置とが第１および第２の光ファイバで接続された光ファイバ無線アクセスシステムであって、前記中央局装置は、光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換する第１の光電気変換部と、前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号が強度変調されたことによって生成された多重光信号を前記第２の光ファイバを経由して受信する受光部と、前記多重光信号から前記アップリンク無線信号を抽出する抽出部と、を備え、前記基地局装置は、前記第１の光ファイバを経由して前記中央局装置から送信された前記ダウンリンク光信号を前記アップリンク無線信号を用いて強度変調することによって、前記アップリンク無線信号と前記ダウンリンク無線信号とを多重した前記多重光信号を生成する多重部と、を備えるものである。 An optical fiber radio access system according to a first aspect of the present invention is an optical fiber radio access system in which a central station apparatus and a base station apparatus are connected by first and second optical fibers, the central station apparatus A first photoelectric conversion unit that converts the downlink radio signal into a downlink optical signal by intensity-modulating the optical signal output from the light source using the downlink radio signal; and the first light A light receiving unit for receiving, via the second optical fiber, a multiplexed optical signal generated by intensity-modulating the downlink optical signal transmitted to the base station device via a fiber; and the multiplexed light And an extraction unit that extracts the uplink radio signal from a signal, wherein the base station device transmits the dashes transmitted from the central station device via the first optical fiber. By intensity modulation using a Nrinku optical signal the uplink radio signal, in which and a multiplexing unit for generating the multiplexed optical signal obtained by multiplexing said downlink radio signal and the uplink radio signal.
　本発明の第２の態様にかかる中央局装置は、基地局装置と第１および第２の光ファイバで接続された中央局装置であって、光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換する第１の光電気変換部と、前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を、前記基地局装置においてアップリンク無線信号を用いて強度変調され、前記アップリンク無線信号と前記ダウンリンク無線信号とが多重された多重光信号から前記アップリンク無線信号を抽出する抽出部と、を備えるものである。 A central station apparatus according to a second aspect of the present invention is a central station apparatus connected to a base station apparatus by first and second optical fibers, and converts an optical signal output from a light source into a downlink radio signal. A first photoelectric conversion unit that converts the downlink radio signal into a downlink optical signal by intensity modulation using the downlink, and the downlink transmitted to the base station apparatus via the first optical fiber. An extraction unit for intensity-modulating an optical signal using an uplink radio signal in the base station apparatus and extracting the uplink radio signal from a multiplexed optical signal in which the uplink radio signal and the downlink radio signal are multiplexed Are provided.
　本発明の第３の態様にかかる基地局装置は、中央局装置と第１および第２の光ファイバで接続された基地局装置であって、前記第１の光ファイバを経由して前記中央局装置から送信された、ダウンリンク光信号をアップリンク無線信号を用いて強度変調することによって、前記アップリンク無線信号と前記ダウンリンク光信号に含まれるダウンリンク無線信号とを多重した多重光信号を生成し、前記多重光信号を第２の光ファイバを経由して前記中央局装置へ送信するものである。 A base station apparatus according to a third aspect of the present invention is a base station apparatus connected to a central station apparatus through first and second optical fibers, and the central station passes through the first optical fiber. A multiplexed optical signal obtained by multiplexing the uplink radio signal and the downlink radio signal included in the downlink optical signal by intensity-modulating the downlink optical signal transmitted from the apparatus using the uplink radio signal. The multiplexed optical signal is generated and transmitted to the central station apparatus via a second optical fiber.
　本発明の第４の態様にかかる抽出方法は、基地局装置と第１および第２の光ファイバで接続された中央局装置において用いられる信号抽出方法であって、光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換し、前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を、前記基地局装置においてアップリンク無線信号を用いて強度変調され、前記アップリンク無線信号と前記ダウンリンク無線信号とが多重された多重光信号を前記第２の光ファイバを経由して受信し、前記多重光信号から前記アップリンク無線信号を抽出するものである。 An extraction method according to a fourth aspect of the present invention is a signal extraction method used in a central station apparatus connected to a base station apparatus through first and second optical fibers, and an optical signal output from a light source is obtained. The downlink radio signal is converted into a downlink optical signal by intensity modulation using a downlink radio signal, and the downlink optical signal transmitted to the base station apparatus via the first optical fiber is converted into the downlink optical signal. Receiving the multiplexed optical signal that is intensity-modulated using an uplink radio signal in the base station apparatus and multiplexed the uplink radio signal and the downlink radio signal via the second optical fiber; The uplink radio signal is extracted from the multiplexed optical signal.
　本発明の第５の態様にかかる通信方法は、中央局装置と第１および第２の光ファイバで接続された基地局装置において用いられる通信方法であって、前記第１の光ファイバを経由して前記中央局装置から送信された、ダウンリンク光信号をアップリンク無線信号を用いて強度変調することによって、前記アップリンク無線信号と前記ダウンリンク光信号に含まれるダウンリンク無線信号とを多重した多重光信号を生成し、前記多重光信号を第２の光ファイバを経由して前記中央局装置へ送信するものである。 A communication method according to a fifth aspect of the present invention is a communication method used in a base station apparatus connected to a central station apparatus through first and second optical fibers, and is routed through the first optical fiber. The uplink radio signal and the downlink radio signal included in the downlink optical signal are multiplexed by intensity-modulating the downlink optical signal transmitted from the central station apparatus using the uplink radio signal. A multiplexed optical signal is generated, and the multiplexed optical signal is transmitted to the central station apparatus via a second optical fiber.
　本発明の第６の態様にかかる記録媒体は、基地局装置と第１および第２の光ファイバで接続されたコンピュータに実行させるプログラムであって、光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換し、前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を、前記基地局装置においてアップリンク無線信号を用いて強度変調され、前記アップリンク無線信号と前記ダウンリンク無線信号とが多重された多重光信号を前記第２の光ファイバを経由して受信し、前記多重光信号から前記アップリンク無線信号を抽出する、ことをコンピュータに実行させるプログラムを記録する非一時的なコンピュータ可読記録媒体である。 A recording medium according to a sixth aspect of the present invention is a program for causing a computer connected to a base station apparatus through first and second optical fibers to execute an optical signal output from a light source as a downlink radio signal. The downlink radio signal is converted into a downlink optical signal by intensity modulation using the base station, and the downlink optical signal transmitted to the base station apparatus via the first optical fiber is converted into the base station. Receiving a multiplexed optical signal, which is intensity-modulated using an uplink radio signal in the apparatus, and multiplexed with the uplink radio signal and the downlink radio signal, via the second optical fiber; A non-transitory computer readable recording medium for recording a program for causing a computer to extract the uplink radio signal from the computer That.
　上記態様により、周波数フィルタを用いることなくアップリンク信号及びダウンリンク信号を分離することができる光ファイバ無線アクセスシステム、中央局装置、基地局装置、抽出方法及び通信方法を提供することができる。 According to the above aspect, it is possible to provide an optical fiber radio access system, a central station apparatus, a base station apparatus, an extraction method, and a communication method that can separate an uplink signal and a downlink signal without using a frequency filter.
実施の形態１にかかる光ファイバ無線アクセスシステムの構成図である。1 is a configuration diagram of an optical fiber wireless access system according to a first embodiment. 実施の形態２にかかる光ファイバ無線アクセスシステムの構成図である。FIG. 3 is a configuration diagram of an optical fiber wireless access system according to a second embodiment. 実施の形態２にかかるＢＢＵにおける信号処理の流れを示す図である。It is a figure which shows the flow of the signal processing in BBU concerning Embodiment 2. FIG. 実施の形態２にかかるＲＲＵにおける信号処理の流れを示す図である。It is a figure which shows the flow of the signal processing in RRU concerning Embodiment 2. FIG. 実施の形態３にかかる光ファイバ無線アクセスシステムの構成図である。FIG. 6 is a configuration diagram of an optical fiber wireless access system according to a third embodiment. 実施の形態３にかかるダウンリンク電気信号のタイムチャートである。It is a time chart of the downlink electric signal concerning Embodiment 3. 実施の形態３にかかるダウンリンク光信号のタイムチャートである。10 is a time chart of a downlink optical signal according to the third embodiment. 実施の形態３にかかるアップリンク電気信号のタイムチャートである。10 is a time chart of uplink electrical signals according to the third exemplary embodiment. 実施の形態３にかかるダウンリンク・アップリンク多重光信号のタイムチャートである。10 is a time chart of a downlink / uplink multiplexed optical signal according to the third embodiment; 実施の形態３にかかるダウンリンク・アップリンク多重電気信号のタイムチャートである。10 is a time chart of a downlink / uplink multiplexed electrical signal according to the third embodiment; 実施の形態３にかかるアップリンク電気信号のタイムチャートである。10 is a time chart of uplink electrical signals according to the third exemplary embodiment. 実施の形態４にかかる光ファイバ無線アクセスシステムの構成図である。FIG. 6 is a configuration diagram of an optical fiber wireless access system according to a fourth embodiment. 実施の形態４にかかる電気信号のタイムチャートである。10 is a time chart of electric signals according to the fourth embodiment. 実施の形態４にかかるアップリンク電気信号のタイムチャートである。It is a time chart of the uplink electric signal concerning Embodiment 4. 実施の形態４にかかるダウンリンク・アップリンク多重電気信号のタイムチャートである。10 is a time chart of a downlink / uplink multiplexed electrical signal according to the fourth embodiment. 実施の形態４にかかるダウンリンク・アップリンク多重光信号のタイムチャートである。10 is a time chart of a downlink / uplink multiplexed optical signal according to the fourth embodiment; 実施の形態４にかかるアップリンク電気信号のタイムチャートである。It is a time chart of the uplink electric signal concerning Embodiment 4. 実施の形態５にかかる光ファイバ無線アクセスシステムの構成図である。FIG. 10 is a configuration diagram of an optical fiber wireless access system according to a fifth embodiment. 実施の形態６にかかる光ファイバ無線アクセスシステムの構成図である。FIG. 10 is a configuration diagram of an optical fiber wireless access system according to a sixth embodiment.
　（実施の形態１）
　以下、図面を参照して本発明の実施の形態について説明する。図１を用いて本発明の実施の形態１にかかる光ファイバ無線アクセスシステムの構成例について説明する。図１の光ファイバ無線アクセスシステムは、中央局装置１００及び基地局装置１１０を有している。中央局装置１００は、光ファイバ１２０及び光ファイバ１３０によって基地局装置１１０と接続している。 (Embodiment 1)
Embodiments of the present invention will be described below with reference to the drawings. A configuration example of the optical fiber radio access system according to the first exemplary embodiment of the present invention will be described with reference to FIG. The optical fiber radio access system in FIG. 1 includes a central station device 100 and a base station device 110. Central station apparatus 100 is connected to base station apparatus 110 by optical fiber 120 and optical fiber 130.
　続いて、中央局装置１００の構成例について説明する。中央局装置１００は、光電気変換部１０１、受光部１０２及び抽出部１０３を有している。 Subsequently, a configuration example of the central station apparatus 100 will be described. The central station apparatus 100 includes a photoelectric conversion unit 101, a light receiving unit 102, and an extraction unit 103.
　光電気変換部１０１は、光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、ダウンリンク無線信号をダウンリンク光信号へ変換する。光源は、例えば、レーザーであってもよい。また、光信号は、レーザーから出力されるＣＷ（Continuous Wave）光であってもよい。また、ダウンリンク無線信号は、電気信号であってもよい。ダウンリンク無線信号は、基地局装置１１０を介して、携帯電話もしくはスマートフォン等の通信端末装置へ送信される信号である。光電気変換部１０１は、ダウンリンク無線信号を光ファイバ１２０を経由して基地局装置１１０へ送信する。 The photoelectric conversion unit 101 converts the downlink radio signal into the downlink optical signal by intensity-modulating the optical signal output from the light source using the downlink radio signal. The light source may be a laser, for example. The optical signal may be CW (ContinuoustinWave) light output from the laser. The downlink radio signal may be an electrical signal. A downlink radio signal is a signal transmitted to a communication terminal device such as a mobile phone or a smartphone via the base station device 110. The photoelectric conversion unit 101 transmits a downlink radio signal to the base station apparatus 110 via the optical fiber 120.
　受光部１０２は、ダウンリンク光信号が強度変調されたことによって生成された多重光信号を光ファイバ１３０を介して受信する。多重光信号は、基地局装置１１０において生成される。 The light receiving unit 102 receives the multiplexed optical signal generated by the intensity modulation of the downlink optical signal via the optical fiber 130. The multiplexed optical signal is generated in the base station device 110.
　抽出部１０３は、受光部１０２において受信した多重光信号から、アップリンク無線信号を抽出する。アップリンク無線信号は、通信端末装置から基地局装置１１０を介して中央局装置１００へ送信される信号である。 The extraction unit 103 extracts an uplink radio signal from the multiplexed optical signal received by the light receiving unit 102. The uplink radio signal is a signal transmitted from the communication terminal apparatus to the central station apparatus 100 via the base station apparatus 110.
　続いて、基地局装置１１０の構成例について説明する。基地局装置１１０は、多重部１１１を有している。多重部１１１は、光ファイバ１２０を経由して中央局装置１００から送信されたダウンリンク光信号を、アップリンク無線信号を用いて強度変調する。これによって、多重部１１１は、アップリンク無線信号とダウンリンク無線信号とを多重した多重光信号を生成する。また、多重部１１１は、多重光信号を光ファイバ１３０を経由して中央局装置１００へ送信する。 Subsequently, a configuration example of the base station apparatus 110 will be described. Base station apparatus 110 has multiplexing section 111. The multiplexing unit 111 modulates the intensity of the downlink optical signal transmitted from the central station apparatus 100 via the optical fiber 120 using the uplink radio signal. Thus, the multiplexing unit 111 generates a multiplexed optical signal obtained by multiplexing the uplink radio signal and the downlink radio signal. The multiplexing unit 111 transmits the multiplexed optical signal to the central station apparatus 100 via the optical fiber 130.
　以上説明したように、図１の光ファイバ無線アクセスシステムにおける基地局装置１１０は、アップリンク無線信号とダウンリンク無線信号とを、ダウンリンク光信号を強度変調することによって多重することができる。そのため、中央局装置１００は、多重光信号からアップリンク無線信号を抽出する際に、周波数フィルタを用いる必要がなくなるため、システムを簡易に構成することができる。さらに、光信号の強度多重を行うことによって、周波数多重を行った際に発生する信号同士が干渉する事象を防止することができる。 As described above, the base station apparatus 110 in the optical fiber radio access system of FIG. 1 can multiplex the uplink radio signal and the downlink radio signal by intensity-modulating the downlink optical signal. Therefore, the central station device 100 does not need to use a frequency filter when extracting the uplink radio signal from the multiplexed optical signal, so that the system can be configured simply. Furthermore, by performing the intensity multiplexing of the optical signal, it is possible to prevent an event in which the signals generated when the frequency multiplexing is performed interfere with each other.
　（実施の形態２）
　続いて、図２を参照して、実施の形態２に係る光ファイバ無線アクセスシステムについて説明する。図２は、実施の形態２に係る光ファイバ無線アクセスシステムの構成図である。図２に示す光ファイバ無線アクセスシステムは、ＢＢＵ（もしくはベースバンド処理装置）１およびＲＲＵ（遠隔無線装置）２を有している。ＢＢＵ１及びＲＲＵ２の間は、光ファイバによる光伝送路７及び８により接続される。 (Embodiment 2)
Next, an optical fiber radio access system according to the second embodiment will be described with reference to FIG. FIG. 2 is a configuration diagram of an optical fiber wireless access system according to the second embodiment. The optical fiber radio access system shown in FIG. 2 has a BBU (or baseband processing unit) 1 and an RRU (remote radio unit) 2. BBU1 and RRU2 are connected by optical transmission lines 7 and 8 using optical fibers.
　ＢＢＵ１は、送受信部（ＴＲＸ）３、光源（レーザーダイオード：ＬＤ）４、光変調器（ＭＯＤ）５、受光器（ＰＤ）１０を備えている。ＲＲＵ２は、光カプラ１３、受光器（ＰＤ）９、バンドパスフィルタ２１、デュプレクサ１１、アンプ２６、光変調器６を備えている。アンテナ１２は、ＲＲＵ２から出力されるダウンリンク電気信号を、送信信号１２ａとして送信する。アンテナ１２は、受信した受信信号１２ｂを、ＲＲＵ２へアップリンク電気信号として出力する。 The BBU 1 includes a transmission / reception unit (TRX) 3, a light source (laser diode: LD) 4, an optical modulator (MOD) 5, and a light receiver (PD) 10. The RRU 2 includes an optical coupler 13, a light receiver (PD) 9, a band pass filter 21, a duplexer 11, an amplifier 26, and an optical modulator 6. The antenna 12 transmits the downlink electrical signal output from the RRU 2 as the transmission signal 12a. The antenna 12 outputs the received reception signal 12b to the RRU 2 as an uplink electrical signal.
　続いて、図２に示す光ファイバ無線アクセスシステムのダウンリンク信号系について説明する。ダウンリンク電気信号３ａは、ＢＢＵ１の送受信部３によりパルス幅変調もしくはパルス位置変調される。また、ダウンリンク電気信号３ａは、送受信部３から出力されるＲＦ帯の１ビットデジタル信号形式の信号である。ダウンリンク電気信号３ａは、光変調器５へ駆動信号として入力される。 Subsequently, the downlink signal system of the optical fiber radio access system shown in FIG. 2 will be described. The downlink electrical signal 3a is subjected to pulse width modulation or pulse position modulation by the transmission / reception unit 3 of the BBU1. The downlink electrical signal 3 a is a signal in the 1-bit digital signal format of the RF band output from the transmission / reception unit 3. The downlink electrical signal 3a is input to the optical modulator 5 as a drive signal.
　光源４は、生成したＣＷ光を光変調器５へ入射する。光変調器５は、ＣＷ光をダウンリンク電気信号３ａを用いて強度変調し、ダウンリンク電気信号３ａをダウンリンク光信号７aへ変換する。 The light source 4 makes the generated CW light enter the optical modulator 5. The optical modulator 5 intensity-modulates the CW light using the downlink electrical signal 3a, and converts the downlink electrical signal 3a into the downlink optical signal 7a.
　ダウンリンク電気信号３ａは、光変調器５において光信号に変換された場合に、光信号がオフしない、もしくは入射されるＣＷ光の最大強度に対して最小強度にならない程度の光強度変調を行うための電圧レベル及び振幅に設定される。言い換えると、ダウンリンク電気信号３ａは、変換後の光信号が光強度のオフセットを含むように光強度変調が行われるための電圧レベル及び振幅に設定される。 When the downlink electrical signal 3a is converted into an optical signal by the optical modulator 5, the optical signal is modulated so that the optical signal does not turn off or does not become the minimum intensity with respect to the maximum intensity of the incident CW light. For the voltage level and amplitude. In other words, the downlink electrical signal 3a is set to a voltage level and amplitude for performing optical intensity modulation so that the converted optical signal includes an optical intensity offset.
　光変調器５は、ダウンリンク電気信号３ａをダウンリンク光信号７ａに変換し、ダウンリンク光信号７ａを、光伝送路７を介してＲＲＵ２へ伝送する。 The optical modulator 5 converts the downlink electrical signal 3a into the downlink optical signal 7a, and transmits the downlink optical signal 7a to the RRU 2 via the optical transmission line 7.
　光カプラ１３は、ＢＢＵ１から伝送された、光強度のオフセットを含むダウンリンク光信号７ａを、ダウンリンク光信号１３ａおよび１３ｂの２系統に分岐する。光カプラ１３は、分岐した一方のダウンリンク光信号１３ａを受光器９へ出力する。受光器９は、光電気変換することによって、ダウンリンク光信号１３ａを電気信号９ａへ変換する。受光器９は、電気信号９ａを、基本波周波数成分のみを通過させるバンドパスフィルタ２１へ出力する。バンドパスフィルタ２１は、電気信号９ａの基本波周波数成分のみを有するダウンリンク電気信号１１ａをデュプレクサ１１の端子Ａへ出力する。 The optical coupler 13 branches the downlink optical signal 7a transmitted from the BBU 1 and including the optical intensity offset into two systems of downlink optical signals 13a and 13b. The optical coupler 13 outputs one of the branched downlink optical signals 13 a to the light receiver 9. The optical receiver 9 converts the downlink optical signal 13a into an electric signal 9a by performing photoelectric conversion. The light receiver 9 outputs the electric signal 9a to the band-pass filter 21 that passes only the fundamental frequency component. The band pass filter 21 outputs a downlink electrical signal 11 a having only the fundamental frequency component of the electrical signal 9 a to the terminal A of the duplexer 11.
　デュプレクサ１１は、ダウンリンク電気信号１１ａを端子Ｂからアンテナ１２へ供給する。つまり、アンテナ１２は、ダウンリンク電気信号１１ａにより駆動され、送信信号１２ａを送出する。 The duplexer 11 supplies the downlink electrical signal 11 a from the terminal B to the antenna 12. That is, the antenna 12 is driven by the downlink electrical signal 11a and transmits the transmission signal 12a.
　次に図２に示す光ファイバ無線アクセスシステムのアップリンク信号系動作について説明する。アンテナ１２は、受信した受信信号１２ｂを、デュプレクサ１１の端子Ｂへ供給する。デュプレクサ１１は、アンテナ１２からの出力、つまりアップリンク電気信号１１ｂを端子Ｃからアンプ２６へ供給する。アンプ２６は、アップリンク電気信号１１ｂを、適当な電圧オフセットレベルおよび振幅を有する電気信号へ変換する。 Next, the uplink signal system operation of the optical fiber radio access system shown in FIG. 2 will be described. The antenna 12 supplies the received reception signal 12b to the terminal B of the duplexer 11. The duplexer 11 supplies the output from the antenna 12, that is, the uplink electrical signal 11b, from the terminal C to the amplifier 26. The amplifier 26 converts the uplink electrical signal 11b into an electrical signal having an appropriate voltage offset level and amplitude.
　アンプ２６は、アップリンク電気信号１１ｂを、適当な電圧オフセットレベルおよび振幅を有する電気信号へ変換し、変換後のアップリンク電気信号２６ａを光変調器６へ出力する。アップリンク電気信号２６ａは、光変調器６の変調信号として光変調器６に入力される。 The amplifier 26 converts the uplink electrical signal 11b into an electrical signal having an appropriate voltage offset level and amplitude, and outputs the converted uplink electrical signal 26a to the optical modulator 6. The uplink electrical signal 26 a is input to the optical modulator 6 as a modulation signal of the optical modulator 6.
　光カプラ１３は、分岐したもう一方のダウンリンク光信号１３ｂを光変調器６へ供給する。光変調器６は、光強度に対してオフセットを有するダウンリンク光信号７ａを、駆動信号であるアップリンク電気信号２６ａを用いて強度変調し、アップリンク電気信号２６ａをダウンリンク・アップリンク多重光信号８ａへ変換する。ダウンリンク・アップリンク多重光信号８ａは、光信号領域の信号強度において、ダウンリンク電気信号３ａとアップリンク電気信号２６ａとが重畳された信号である。 The optical coupler 13 supplies the other branched downlink optical signal 13 b to the optical modulator 6. The optical modulator 6 intensity-modulates the downlink optical signal 7a having an offset with respect to the optical intensity by using the uplink electrical signal 26a that is a drive signal, and the uplink electrical signal 26a is downlink / uplink multiplexed light. Convert to signal 8a. The downlink / uplink multiplexed optical signal 8a is a signal obtained by superimposing the downlink electrical signal 3a and the uplink electrical signal 26a in the signal strength of the optical signal region.
　つまり、光変調器６は、アップリンク電気信号２６ａをダウンリンク電気信号３ａに重畳すべく、ダウンリンク光信号１３ｂをアップリンク電気信号２６ａを用いて、さらに変調する。 That is, the optical modulator 6 further modulates the downlink optical signal 13b using the uplink electrical signal 26a in order to superimpose the uplink electrical signal 26a on the downlink electrical signal 3a.
　光変調器６は、ダウンリンク・アップリンク多重光信号８ａを、光伝送路８を介してＢＢＵ１へ伝送する。受光器１０は、ＲＲＵ２から伝送されたダウンリンク・アップリンク多重光信号８ａを、ダウンリンク・アップリンク多重電気信号１０ａへ変換する。受光器１０は、ダウンリンク・アップリンク多重電気信号１０ａを送受信部３へ出力する。 The optical modulator 6 transmits the downlink / uplink multiplexed optical signal 8 a to the BBU 1 through the optical transmission line 8. The optical receiver 10 converts the downlink / uplink multiplexed optical signal 8a transmitted from the RRU 2 into a downlink / uplink multiplexed electrical signal 10a. The light receiver 10 outputs a downlink / uplink multiplexed electrical signal 10 a to the transmission / reception unit 3.
　送受信部３は、デジタル信号処理によってダウンリンク・アップリンク多重電気信号１０ａからダウンリンク電気信号３ａを差し引くことによってアップリンク信号を抽出する。 The transmission / reception unit 3 extracts the uplink signal by subtracting the downlink electrical signal 3a from the downlink / uplink multiplexed electrical signal 10a by digital signal processing.
　続いて、図３を用いて、ＢＢＵ１における信号処理の流れについて説明する。はじめに、光変調器５は、ダウンリンク電気信号３ａを駆動信号として、光源４において生成されたＣＷ光を強度変調する（Ｓ１１）。 Subsequently, the flow of signal processing in the BBU 1 will be described with reference to FIG. First, the optical modulator 5 intensity-modulates the CW light generated in the light source 4 using the downlink electrical signal 3a as a drive signal (S11).
　次に、光変調器５は、ダウンリンク電気信号３ａによって強度変調されたＣＷ光をダウンリンク光信号７ａとして、光伝送路７を経由してＲＲＵ２へ送信する（Ｓ１２）。言い換えると、光変調器５は、ダウンリンク電気信号３ａをダウンリンク光信号７ａへ変換し、ダウンリンク光信号７ａをＲＲＵ２へ送信する。 Next, the optical modulator 5 transmits the CW light intensity-modulated by the downlink electrical signal 3a as the downlink optical signal 7a to the RRU 2 via the optical transmission line 7 (S12). In other words, the optical modulator 5 converts the downlink electrical signal 3a into the downlink optical signal 7a, and transmits the downlink optical signal 7a to the RRU 2.
　次に、受光器１０は、ＲＲＵ２から送信されたダウンリンク・アップリンク多重光信号８ａを受信する（Ｓ１３）。次に、受光器１０は、光電変換によりダウンリンク・アップリンク多重光信号８ａを、ダウンリンク・アップリンク多重電気信号１０ａへ変換する（Ｓ１４）。次に、送受信部３は、ダウンリンク・アップリンク多重電気信号１０ａから、ダウンリンク電気信号４ａを差し引くことによってアップリンク電気信号を抽出する（Ｓ１５）。 Next, the optical receiver 10 receives the downlink / uplink multiplexed optical signal 8a transmitted from the RRU 2 (S13). Next, the optical receiver 10 converts the downlink / uplink multiplexed optical signal 8a into a downlink / uplink multiplexed electrical signal 10a by photoelectric conversion (S14). Next, the transmitting / receiving unit 3 extracts the uplink electrical signal by subtracting the downlink electrical signal 4a from the downlink / uplink multiplexed electrical signal 10a (S15).
　続いて、図４を用いて、ＲＲＵ２における信号処理の流れについて説明する。はじめに、光カプラ１３は、光伝送路７を経由してダウンリンク光信号７ａを受信する（Ｓ２１）。次に、光カプラ１３は、ダウンリンク光信号７ａを分岐し、一方のダウンリンク光信号１３ｂを光変調器６へ出力する（Ｓ２２）。 Subsequently, the flow of signal processing in the RRU 2 will be described with reference to FIG. First, the optical coupler 13 receives the downlink optical signal 7a via the optical transmission line 7 (S21). Next, the optical coupler 13 branches the downlink optical signal 7a and outputs one downlink optical signal 13b to the optical modulator 6 (S22).
　次に、光変調器６は、アンテナ１２において受信し、アンプ２６において、適当な電圧オフセットレベルおよび振幅を有する電気信号へ変換されたアップリンク電気信号２６ａを駆動信号として、ダウンリンク光信号１３ｂを強度変調する（Ｓ２３）。次に、光変調器６は、アップリンク電気信号２６ａによって強度変調されたダウンリンク光信号１３ｂをダウンリンク・アップリンク多重光信号８ａとして、光伝送路８を経由してＢＢＵ１へ送信する（Ｓ２４）。 Next, the optical modulator 6 receives the downlink optical signal 13b by using the uplink electrical signal 26a received by the antenna 12 and converted by the amplifier 26 into an electrical signal having an appropriate voltage offset level and amplitude as a drive signal. The intensity is modulated (S23). Next, the optical modulator 6 transmits the downlink optical signal 13b intensity-modulated by the uplink electrical signal 26a as the downlink / uplink multiplexed optical signal 8a to the BBU 1 via the optical transmission line 8 (S24). ).
　以上説明したように、本発明の実施の形態２にかかる光ファイバ無線アクセスシステムを用いることによって、ＲＲＵ２に光源を配置することなく、アップリンク及びダウンリンクの双方の光ファイバ無線通信を実現することができる。さらに、ＢＢＵ１の光変調器５及びＲＲＵ２の光変調器６は、電気信号を用いて光信号を強度変調する。そのため、ＢＢＵ１は、強度変調された光信号を復調する際に、周波数フィルタを用いる必要がないため、構成が簡略化される。 As described above, by using the optical fiber radio access system according to the second exemplary embodiment of the present invention, both uplink and downlink optical fiber radio communications can be realized without arranging a light source in the RRU 2. Can do. Further, the optical modulator 5 of the BBU1 and the optical modulator 6 of the RRU2 intensity-modulate the optical signal using the electric signal. Therefore, the configuration of the BBU 1 is simplified because it is not necessary to use a frequency filter when demodulating an intensity-modulated optical signal.
　（実施の形態３）
　続いて、図５を用いて実施の形態３に係る光ファイバ無線アクセスシステムについて説明する。図５におけるＢＢＵ１は、図２のＢＢＵ１に、コンパレータ２２が追加されている。図５におけるＢＢＵ１のその他の構成は、図２のＢＢＵ１と同様であるため詳細な説明を省略する。また、図５におけるＲＲＵ２は、図２のＲＲＵ２におけるアンプ２６が、データ変換回路２５に置き換えられている。図５におけるＲＲＵ２のその他の構成は、図２のＲＲＵ２と同様であるため詳細な説明を省略する。 (Embodiment 3)
Next, the optical fiber radio access system according to the third embodiment will be described with reference to FIG. The BBU 1 in FIG. 5 has a comparator 22 added to the BBU 1 in FIG. The other configuration of BBU1 in FIG. 5 is the same as that of BBU1 in FIG. In the RRU 2 in FIG. 5, the amplifier 26 in the RRU 2 in FIG. 2 is replaced with a data conversion circuit 25. The other configuration of the RRU 2 in FIG. 5 is the same as that of the RRU 2 in FIG.
　コンパレータ２２は、ダウンリンク・アップリンク多重電気信号１０ａからアップリンク電気信号の１ビットデジタル信号を抽出するための閾値に従い動作する。コンパレータ２２は、抽出した信号をアップリンク電気信号２２ａとして送受信部３へ出力する。 The comparator 22 operates according to a threshold value for extracting the 1-bit digital signal of the uplink electrical signal from the downlink / uplink multiplexed electrical signal 10a. The comparator 22 outputs the extracted signal to the transmission / reception unit 3 as an uplink electrical signal 22a.
　データ変換回路２５は、パルス幅変調もしくはパルス位置変調等のパルス変調を行うことによって、受信信号を、ＲＦ帯の１ビットデジタル形式のアップリンク電気信号２５ａへ変換する。 The data conversion circuit 25 converts the received signal into a 1-bit digital format uplink electrical signal 25a in the RF band by performing pulse modulation such as pulse width modulation or pulse position modulation.
　続いて、図６～図１１を用いて、実施の形態３における各主要箇所の電気信号もしくは光信号のタイムチャート図を含め、当該光ファイバ無線アクセスシステムの動作を説明する。 Subsequently, the operation of the optical fiber radio access system will be described with reference to FIGS. 6 to 11 including time charts of electric signals or optical signals at respective main points in the third embodiment.
　はじめに、ダウンリンク信号系について説明する。図６に示すダウンリンク電気信号３ａは、ＢＢＵ１の送受信部３によりパルス幅変調もしくはパルス位置変調されたＲＦ帯の１ビットデジタル信号形式の信号である。図６は、縦軸が電圧レベルを示し、横軸が時間を示している。ダウンリンク電気信号３ａは、電圧レベル２と電圧レベル３との間において遷移する。つまり、ダウンリンク電気信号３ａは、電圧レベル０から電圧レベル２までのオフセットを有する。 First, the downlink signal system will be described. The downlink electrical signal 3a shown in FIG. 6 is a signal in the RF band 1-bit digital signal format that is pulse width modulated or pulse position modulated by the transceiver 3 of the BBU1. In FIG. 6, the vertical axis represents the voltage level, and the horizontal axis represents time. Downlink electrical signal 3 a transitions between voltage level 2 and voltage level 3. That is, the downlink electrical signal 3a has an offset from voltage level 0 to voltage level 2.
　図７に示すダウンリンク光信号７ａは、光源４により生成されたＣＷ光が、光変調器５において、ダウンリンク電気信号３ａによって強度変調された信号である。図７は、縦軸が光強度を示し、横軸が時間を示している。ダウンリンク光信号７ａは、光強度２と光強度３との間において遷移する。ダウンリンク光信号７ａは、光強度０から光強度２までのオフセットを有する。ダウンリンク光信号７ａは、無変調のＣＷ光がダウンリンク電気信号３ａを用いて強度変調されているため、ダウンリンク電気信号と同様の波形を示している。 The downlink optical signal 7a shown in FIG. 7 is a signal obtained by intensity-modulating the CW light generated by the light source 4 with the downlink electrical signal 3a in the optical modulator 5. In FIG. 7, the vertical axis indicates the light intensity, and the horizontal axis indicates time. The downlink optical signal 7 a transitions between the light intensity 2 and the light intensity 3. The downlink optical signal 7a has an offset from light intensity 0 to light intensity 2. The downlink optical signal 7a has a waveform similar to that of the downlink electrical signal because the unmodulated CW light is intensity-modulated using the downlink electrical signal 3a.
　次にアップリンク信号について説明する。図８に示すアップリンク電気信号２５ａは、アンテナが受信した受信信号がデータ変換回路２５において変換された信号である。図８は、縦軸が電圧レベルを示し、横軸が時間を示している。アップリンク電気信号２５ａは、電圧レベル０と電圧レベル３との間において遷移する。つまり、アップリンク電気信号２５ａは、ダウンリンク電気信号３ａのようなオフセットを有さない。 Next, the uplink signal will be described. The uplink electrical signal 25a shown in FIG. 8 is a signal obtained by converting the reception signal received by the antenna in the data conversion circuit 25. In FIG. 8, the vertical axis indicates the voltage level, and the horizontal axis indicates time. Uplink electrical signal 25a transitions between voltage level 0 and voltage level 3. That is, the uplink electrical signal 25a does not have an offset like the downlink electrical signal 3a.
　図９に示すダウンリンク・アップリンク多重光信号は、ダウンリンク光信号１３ｂが、光変調器６において、アップリンク電気信号２５ａによって強度変調された信号である。
図９は、縦軸が光強度を示し、横軸が時間を示している。ダウンリンク・アップリンク多重光信号８ａは、光強度０と光強度３との間において遷移する。ダウンリンク・アップリンク多重光信号８ａは、図９に示されているように、アップリンク電気信号２５ａにダウンリンク電気信号３ａが多重されている。言い換えると、アップリンク電気信号２５ａは、光強度に対しオフセットを有するダウンリンク光信号７ａのオフセット分を利用し、ダウンリンク光信号７ａの変調を行う。つまり、光変調器６は、ダウンリンク光信号７ａにアップリンク電気信号２５ａを重畳すべく、ダウンリンク光信号７ａが十分にオフするだけの駆動電圧によって強度変調を行う。 The downlink / uplink multiplexed optical signal shown in FIG. 9 is a signal obtained by intensity-modulating the downlink optical signal 13b in the optical modulator 6 with the uplink electrical signal 25a.
In FIG. 9, the vertical axis indicates the light intensity, and the horizontal axis indicates time. The downlink / uplink multiplexed optical signal 8 a transitions between light intensity 0 and light intensity 3. In the downlink / uplink multiplexed optical signal 8a, as shown in FIG. 9, the downlink electrical signal 3a is multiplexed with the uplink electrical signal 25a. In other words, the uplink electrical signal 25a modulates the downlink optical signal 7a using the offset of the downlink optical signal 7a having an offset with respect to the optical intensity. In other words, the optical modulator 6 performs intensity modulation with a drive voltage sufficient to turn off the downlink optical signal 7a in order to superimpose the uplink electrical signal 25a on the downlink optical signal 7a.
　図１０に示すダウンリンク・アップリンク多重電気信号１０ａは、受光器１０において、ダウンリンク光信号７ａから変換された電気信号である。図１０は、縦軸が電圧レベルを示し、横軸が時間を示している。ダウンリンク・アップリンク多重電気信号１０ａは、ダウンリンク・アップリンク多重光信号８ａと同様の波形を示している。 A downlink / uplink multiplexed electrical signal 10a shown in FIG. 10 is an electrical signal converted from the downlink optical signal 7a in the optical receiver 10. In FIG. 10, the vertical axis indicates the voltage level, and the horizontal axis indicates time. The downlink / uplink multiplexed electrical signal 10a shows a waveform similar to that of the downlink / uplink multiplexed optical signal 8a.
　図１１のアップリンク電気信号２２ａは、コンパレータ２２の出力結果である。コンパレータ２２は、例えば、電圧レベル１を閾値として、ダウンリンク・アップリンク多重電気信号１０ａの電圧レベルが１より大きい期間をＨレベルとして出力し、ダウンリンク・アップリンク多重電気信号１０ａの電圧レベルが１以下の期間をＬレベルとして出力する。 The uplink electrical signal 22a in FIG. The comparator 22 outputs, for example, a period in which the voltage level of the downlink / uplink multiplexed electric signal 10a is higher than 1 with the voltage level 1 as a threshold, and the voltage level of the downlink / uplink multiplexed electric signal 10a is A period of 1 or less is output as an L level.
　図１１のアップリンク電気信号２２ａは、図８のアップリンク電気信号２５ａと同様の波形を示している。つまり、コンパレータ２２は、ダウンリンク・アップリンク多重電気信号１０ａから、アップリンク電気信号２５ａを抽出する。 The uplink electrical signal 22a in FIG. 11 shows the same waveform as the uplink electrical signal 25a in FIG. That is, the comparator 22 extracts the uplink electrical signal 25a from the downlink / uplink multiplexed electrical signal 10a.
　以上説明したように、本発明の実施の形態３にかかる光ファイバ無線アクセスシステムは、図２の光ファイバ無線アクセスシステムを用いた場合と同様に、ＲＲＵ２に光源を配置することなく、アップリンク及びダウンリンクの双方の光ファイバ無線通信を実現することができる。さらに、ＢＢＵ１の光変調器５及びＲＲＵ２の光変調器６は、電気信号を用いて光信号を強度変調する。そのため、ＢＢＵ１は、強度変調された光信号を復調する際に、周波数フィルタを用いる必要がないため、構成が簡略化される。 As described above, the optical fiber radio access system according to the third exemplary embodiment of the present invention is similar to the case of using the optical fiber radio access system of FIG. It is possible to realize both-fiber optical fiber communication in the downlink. Further, the optical modulator 5 of the BBU1 and the optical modulator 6 of the RRU2 intensity-modulate the optical signal using the electric signal. Therefore, the configuration of the BBU 1 is simplified because it is not necessary to use a frequency filter when demodulating an intensity-modulated optical signal.
　（実施の形態４）
　続いて、図１２を用いて実施の形態４に係る光ファイバ無線アクセスシステムについて説明する。図１２におけるＲＲＵ２は、図５のＲＲＵ２に、減算器２４が追加されている。図１２におけるＲＲＵ２のその他の構成は、図２のＲＲＵ２と同様であるため詳細な説明を省略する。また、図１２におけるＢＢＵ１は、図１のＢＢＵ１と同様である。 (Embodiment 4)
Next, an optical fiber wireless access system according to the fourth embodiment will be described with reference to FIG. In RRU2 in FIG. 12, a subtracter 24 is added to RRU2 in FIG. Other configurations of the RRU 2 in FIG. 12 are the same as those of the RRU 2 in FIG. Further, BBU1 in FIG. 12 is the same as BBU1 in FIG.
　減算器２４は、受光器９から出力された電気信号９ａであって、２系統に分岐されたうちの一方の電気信号９ａを受け取る。減算器２４は、データ変換回路２５から出力されたアップリンク電気信号２５ａから電気信号９ａを電圧ドメインにおいて減算する。電圧ドメインにおいて減算するとは、アップリンク電気信号２５ａが示す電圧レベルから、電気信号９ａが示す電圧レベルを減算することである。 The subtracter 24 receives the electric signal 9a output from the light receiver 9 and one of the two branched signals. The subtractor 24 subtracts the electrical signal 9a from the uplink electrical signal 25a output from the data conversion circuit 25 in the voltage domain. Subtracting in the voltage domain means subtracting the voltage level indicated by the electrical signal 9a from the voltage level indicated by the uplink electrical signal 25a.
　減算器２４は、アップリンク電気信号２５ａから電気信号９ａを減算した結果であるダウンリンク・アップリンク多重電気信号２４ａを光変調器６へ出力する。 The subtractor 24 outputs a downlink / uplink multiplexed electrical signal 24a, which is a result of subtracting the electrical signal 9a from the uplink electrical signal 25a, to the optical modulator 6.
　続いて、図１３～図１７を用いて、実施の形態４における各主要箇所の電気信号もしくは光信号のタイムチャート図を含め、当該光ファイバ無線アクセスシステムの動作を説明する。 Subsequently, the operation of the optical fiber radio access system will be described with reference to FIGS. 13 to 17 including time charts of electric signals or optical signals at respective main points in the fourth embodiment.
　図１３の電気信号９ａは、受光器９から出力された電気信号９ａであって、２系統に分岐されたうちの一方の電気信号を示している。電気信号９ａは、ダウンリンク光信号７ａから変換された電気信号であり、電圧レベル０と電圧レベル１との間を遷移する。電気信号９ａは、ダウンリンク光信号７ａとオフセットの位置が異なるが、同様の波形を有している。 The electrical signal 9a in FIG. 13 is the electrical signal 9a output from the light receiver 9, and shows one of the electrical signals branched into two systems. The electrical signal 9a is an electrical signal converted from the downlink optical signal 7a, and transits between the voltage level 0 and the voltage level 1. The electrical signal 9a has the same waveform as the downlink optical signal 7a, although the offset position is different.
　図１４に示すアップリンク電気信号２５ａは、アンテナが受信した受信信号がデータ変換回路２５において変換された信号である。図１４は、縦軸が電圧レベルを示し、横軸が時間を示している。アップリンク電気信号２５ａは、電圧レベル１と電圧レベル３との間において遷移する。つまり、アップリンク電気信号２５ａは、電圧レベル０から電圧レベル１までのオフセットを有する。 The uplink electrical signal 25a shown in FIG. 14 is a signal obtained by converting the received signal received by the antenna in the data conversion circuit 25. In FIG. 14, the vertical axis indicates the voltage level and the horizontal axis indicates time. Uplink electrical signal 25a transitions between voltage level 1 and voltage level 3. That is, the uplink electrical signal 25a has an offset from voltage level 0 to voltage level 1.
　図１５に示すダウンリンク・アップリンク多重電気信号２４ａは、図１４に示すアップリンク電気信号２５ａから、図１３に示す電気信号９ａを、電圧ドメインにおいて減算した後の波形を示している。 The downlink / uplink multiplexed electrical signal 24a shown in FIG. 15 shows a waveform after the electrical signal 9a shown in FIG. 13 is subtracted in the voltage domain from the uplink electrical signal 25a shown in FIG.
　図１６に示すダウンリンク・アップリンク多重光信号８ｂは、光変調器６によって、ダウンリンク・アップリンク多重電気信号２４ａを用いて、強度変調が行われた信号である。ダウンリンク・アップリンク多重電気信号２４ａは、アップリンク電気信号２５ａから、ダウンリンク電気信号を示す電気信号９ａが減算された信号である。さらに、ダウンリンク・アップリンク多重光信号８ｂは、光信号領域の信号強度において、ダウンリンク・アップリンク多重電気信号２４ａとダウンリンク電気信号３ａとが重畳された信号である。そのため、ダウンリンク・アップリンク多重光信号８ｂは、ダウンリンク光信号７ａ分の光強度が相殺され、アップリンク電気信号２５ａと同様の波形を示す。 The downlink / uplink multiplexed optical signal 8b shown in FIG. 16 is a signal that has been intensity-modulated by the optical modulator 6 using the downlink / uplink multiplexed electrical signal 24a. The downlink / uplink multiplexed electrical signal 24a is a signal obtained by subtracting the electrical signal 9a indicating the downlink electrical signal from the uplink electrical signal 25a. Further, the downlink / uplink multiplexed optical signal 8b is a signal obtained by superimposing the downlink / uplink multiplexed electrical signal 24a and the downlink electrical signal 3a in the signal strength of the optical signal region. Therefore, the downlink / uplink multiplexed optical signal 8b cancels out the optical intensity corresponding to the downlink optical signal 7a, and shows a waveform similar to that of the uplink electrical signal 25a.
　図１７のアップリンク電気信号１０ｂは、受光器１０において、ダウンリンク・アップリンク多重光信号８ｂから変換された電気信号である。アップリンク電気信号１０ｂは、アップリンク電気信号２５ａと同様の波形を示す。 The uplink electrical signal 10b in FIG. 17 is an electrical signal converted from the downlink / uplink multiplexed optical signal 8b in the optical receiver 10. Uplink electrical signal 10b shows a waveform similar to uplink electrical signal 25a.
　以上説明したように、本発明の実施の形態４にかかる光ファイバ無線アクセスシステムは、実施の形態２及び３の光ファイバ無線アクセスシステムを用いた場合と同様に、ＲＲＵ２に光源を配置することなく、アップリンク及びダウンリンクの双方の光ファイバ無線通信を実現することができる。また、ＲＲＵ２は、減算器２４を用いることによって、光変調器６においてアップリンク電気信号２５ａのみを含むダウンリンク・アップリンク多重光信号を生成することができる。そのため、ＢＢＵ１の受光器１０は、ダウンリンク電気信号を含まないアップリンク電気信号１０ｂを生成することができる。これにより、ＢＢＵ１における処理を低減させることができる。 As described above, the optical fiber radio access system according to the fourth exemplary embodiment of the present invention is the same as when the optical fiber radio access system according to the second and third exemplary embodiments is used, without arranging a light source in the RRU 2. Both uplink and downlink optical fiber radio communication can be realized. Also, the RRU 2 can generate a downlink / uplink multiplexed optical signal including only the uplink electrical signal 25a in the optical modulator 6 by using the subtractor 24. Therefore, the light receiver 10 of the BBU 1 can generate the uplink electrical signal 10b that does not include the downlink electrical signal. Thereby, the process in BBU1 can be reduced.
　（実施の形態５）
　続いて、図１８を参照して、実施の形態５に係る光ファイバ無線アクセスシステムについて説明する。図１８におけるＲＲＵ２は、図１２におけるＲＲＵ２のデータ変換回路２５をアンプ２６に置き換えている。図１８におけるＲＲＵ２のその他の構成、及びＢＢＵ１の構成は、図１２のＢＢＵ１及びＲＲＵ２と同様であるため詳細な説明を省略する。 (Embodiment 5)
Next, the optical fiber radio access system according to the fifth embodiment will be described with reference to FIG. The RRU 2 in FIG. 18 replaces the data conversion circuit 25 of the RRU 2 in FIG. The other configuration of RRU2 and the configuration of BBU1 in FIG. 18 are the same as BBU1 and RRU2 in FIG.
　減算器２４は、アンプ２６において増幅されたアップリンク電気信号１１ｂから、電気信号９ａを減算する。減算器２４は、減算結果である、ダウンリンク・アップリンク多重電気信号２４ａを、光変調器６へ出力する。ここで、ダウンリンク・アップリンク多重電気信号２４ａは、図１５のダウンリンク・アップリンク多重電気信号２４ａと同様の波形を示す。そのため、ＢＢＵ１の受光器１０は、図１７のアップリンク電気信号１０ｂと同様のアップリンク電気信号１０ｂを抽出することができる。 The subtracter 24 subtracts the electrical signal 9a from the uplink electrical signal 11b amplified by the amplifier 26. The subtractor 24 outputs a downlink / uplink multiplexed electric signal 24a, which is a subtraction result, to the optical modulator 6. Here, the downlink / uplink multiplexed electrical signal 24a has the same waveform as the downlink / uplink multiplexed electrical signal 24a of FIG. Therefore, the optical receiver 10 of BBU1 can extract the uplink electrical signal 10b similar to the uplink electrical signal 10b of FIG.
　以上説明したように、本発明の実施の形態５にかかる光ファイバ無線アクセスシステムは、実施の形態２～４の光ファイバ無線アクセスシステムを用いた場合と同様に、ＲＲＵ２に光源を配置することなく、アップリンク及びダウンリンクの双方の光ファイバ無線通信を実現することができる。また、ＢＢＵ１は、ダウンリンク・アップリンク多重光信号から、ダウンリンク電気信号を取り除く処理を行う必要がない。そのため、ＢＢＵ１における処理負担を軽減させることができる。 As described above, the optical fiber radio access system according to the fifth embodiment of the present invention is the same as when using the optical fiber radio access system according to the second to fourth embodiments without arranging a light source in the RRU 2. Both uplink and downlink optical fiber radio communication can be realized. Further, the BBU 1 does not need to perform processing for removing the downlink electrical signal from the downlink / uplink multiplexed optical signal. Therefore, the processing burden on BBU1 can be reduced.
　（実施の形態６）
　続いて、図１９を参照して、実施の形態６に係る光ファイバ無線アクセスシステムについて説明する。図１９におけるＲＲＵ２は、図５におけるＲＲＵ２と同様である。図１９におけるＢＢＵ１は、図２におけるＢＢＵ１に、遅延回路２７及び減算器２８を追加している。図１９におけるＢＢＵ１のその他の構成は、図２におけるＢＢＵ１の構成と同様であるため詳細な説明を省略する。 (Embodiment 6)
Next, an optical fiber radio access system according to the sixth embodiment will be described with reference to FIG. RRU2 in FIG. 19 is the same as RRU2 in FIG. In BBU1 in FIG. 19, a delay circuit 27 and a subtracter 28 are added to BBU1 in FIG. The other configuration of BBU1 in FIG. 19 is the same as the configuration of BBU1 in FIG.
　ここで、遅延回路２７及び減算器２８を用いた場合のアップリンク信号系の動作について説明する。受光器１０は、図５における動作と同様に、ダウンリンク・アップリンク多重光信号８ａを受信する。さらに、受光器１０は、ダウンリンク・アップリンク多重光信号８ａを、ダウンリンク・アップリンク多重電気信号１０ａへ変換する。受光器１０は、ダウンリンク・アップリンク多重電気信号１０ａを減算器２８へ出力する。 Here, the operation of the uplink signal system when the delay circuit 27 and the subtracter 28 are used will be described. The optical receiver 10 receives the downlink / uplink multiplexed optical signal 8a as in the operation in FIG. Furthermore, the optical receiver 10 converts the downlink / uplink multiplexed optical signal 8a into a downlink / uplink multiplexed electrical signal 10a. The light receiver 10 outputs a downlink / uplink multiplexed electrical signal 10 a to the subtractor 28.
　減算器２８は、ダウンリンク・アップリンク多重電気信号１０ａからダウンリンク電気信号２７ａを電圧ドメインにおいて減算する。ダウンリンク電気信号２７ａは、２系統に分岐されたダウンリンク電気信号３ａの一方のダウンリンク電気信号３ａに、遅延回路２７において遅延が加えられた電気信号である。 The subtracter 28 subtracts the downlink electrical signal 27a from the downlink / uplink multiplexed electrical signal 10a in the voltage domain. The downlink electrical signal 27a is an electrical signal obtained by adding a delay in the delay circuit 27 to one downlink electrical signal 3a of the downlink electrical signal 3a branched into two systems.
　遅延回路２７は、ダウンリンク・アップリンク多重電気信号１０ａから、ダウンリンク電気信号３ａを減算できるようなタイミングとなるようにダウンリンク電気信号３ａを出力するタイミングを調整する。つまり、遅延回路２７は、光変調器５、光カプラ１３、光変調器６及び受光器１０における処理遅延、さらに、光伝送路７及び光伝送路８における伝送遅延を考慮して、ダウンリンク電気信号２７ａを出力するタイミングを調整してもよい。減算器２８は、ダウンリンク・アップリンク多重電気信号１０ａからダウンリンク電気信号２７ａを電圧ドメインにおいて減算することによって、ダウンリンク電気信号３ａが除かれたアップリンク電気信号２８ａを送受信部３へ出力することができる。 The delay circuit 27 adjusts the timing for outputting the downlink electrical signal 3a so that the downlink electrical signal 3a can be subtracted from the downlink / uplink multiplexed electrical signal 10a. That is, the delay circuit 27 takes into account the processing delay in the optical modulator 5, the optical coupler 13, the optical modulator 6, and the light receiver 10, and further the transmission delay in the optical transmission path 7 and the optical transmission path 8. The timing for outputting the signal 27a may be adjusted. The subtractor 28 subtracts the downlink electrical signal 27a from the downlink / uplink multiplexed electrical signal 10a in the voltage domain, and outputs the uplink electrical signal 28a from which the downlink electrical signal 3a has been removed to the transceiver unit 3. be able to.
　以上説明したように、本発明の実施の形態６にかかる光ファイバ無線アクセスシステムは、実施の形態２～５の光ファイバ無線アクセスシステムを用いた場合と同様に、ＲＲＵ２に光源を配置することなく、アップリンク及びダウンリンクの双方の光ファイバ無線通信を実現することができる。さらに、ＢＢＵ１は、減算器２８を用いることによって、処理負荷が高い周波数フィルタを用いる必要がなくなる。 As described above, the optical fiber radio access system according to the sixth embodiment of the present invention is the same as when using the optical fiber radio access system according to the second to fifth embodiments, without arranging a light source in the RRU 2. Both uplink and downlink optical fiber radio communication can be realized. Further, the BBU 1 does not need to use a frequency filter with a high processing load by using the subtractor 28.
　上述の実施の形態では、本発明をハードウェアの構成として説明したが、本発明は、これに限定されるものではない。本発明は、ＢＢＵ１及びＲＲＵ２における処理を、ＣＰＵ（Central Processing Unit）にコンピュータプログラムを実行させることにより実現することも可能である。 In the above-described embodiment, the present invention has been described as a hardware configuration, but the present invention is not limited to this. The present invention can also realize the processing in BBU1 and RRU2 by causing a CPU (Central Processing Unit) to execute a computer program.
　上述の例において、プログラムは、様々なタイプの非一時的なコンピュータ可読媒体（non-transitory computer readable medium）を用いて格納され、コンピュータに供給することができる。非一時的なコンピュータ可読媒体は、様々なタイプの実体のある記録媒体（tangible storage medium）を含む。非一時的なコンピュータ可読媒体の例は、磁気記録媒体（例えばフレキシブルディスク、磁気テープ、ハードディスクドライブ）、光磁気記録媒体（例えば光磁気ディスク）、ＣＤ（Compact Disc）－ＲＯＭ（Read Only Memory）、ＣＤ－Ｒ(Recordable)、ＣＤ－Ｒ／Ｗ(ReWritable)、半導体メモリ（例えば、マスクＲＯＭ、ＰＲＯＭ（Programmable ROM）、ＥＰＲＯＭ（Erasable PROM）、フラッシュＲＯＭ、ＲＡＭ（Random Access Memory））を含む。
また、プログラムは、様々なタイプの一時的なコンピュータ可読媒体（transitory computer readable medium）によってコンピュータに供給されてもよい。一時的なコンピュータ可読媒体の例は、電気信号、光信号、及び電磁波を含む。一時的なコンピュータ可読媒体は、電線及び光ファイバ等の有線通信路、又は無線通信路を介して、プログラムをコンピュータに供給できる。 In the above example, the program can be stored and supplied to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD (Compact Disc) -ROM (Read Only Memory), CD-R (Recordable), CD-R / W (ReWritable), semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)).
The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.
　以上、実施形態を参照して本願発明を説明したが、本願発明は上記実施形態に限定されるものではない。本願発明の構成や詳細には、本願発明のスコープ内で当業者が理解し得る様々な変更をすることができる。
While the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.
　上記の実施形態の一部又は全部は、以下の付記のようにも記載されうるが、以下には限られない。 Some or all of the above embodiments can be described as in the following supplementary notes, but are not limited thereto.
　（付記１）中央局装置と基地局装置とが第１および第２の光ファイバで接続された光ファイバ無線アクセスシステムにおいて、前記中央局装置は、光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換する第１の光電気変換手段と、前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号が強度変調されたことによって生成された多重光信号を前記第２の光ファイバを経由して受信する受光手段と、前記多重光信号から前記アップリンク無線信号を抽出する抽出手段と、を備え、前記基地局装置は、前記第１の光ファイバを経由して前記中央局装置から送信された前記ダウンリンク光信号を前記アップリンク無線信号を用いて強度変調することによって、前記アップリンク無線信号と前記ダウンリンク無線信号とを多重した前記多重光信号を生成する多重手段と、を備える光ファイバ無線アクセスシステム。
　（付記２）前記中央局装置は、前記多重光信号を多重無線信号へ変換する第２の光電気変換手段をさらに備え、前記抽出手段は、コンパレータ回路を用いることによって前記多重無線信号から前記アップリンク無線信号を抽出する、付記１に記載の光ファイバ無線アクセスシステム。
　（付記３）前記中央局装置は、前記多重光信号を多重無線信号へ変換する第２の光電気変換手段をさらに備え、前記抽出手段は、減算回路を用いて前記多重無線信号から前記ダウンリンク無線信号を減算することによって、前記アップリンク無線信号を抽出する、付記１に記載の光ファイバ無線アクセスシステム。
　（付記４）中央局装置と基地局装置とが第１および第２の光ファイバで接続された光ファイバ無線アクセスシステムにおいて、前記中央局装置は、光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換する第１の光電気変換手段と、前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を強度変調することによって生成された多重光信号を前記第２の光ファイバを経由して受信する受光手段と、を備え、前記基地局装置は、前記第１の光ファイバを経由して前記中央局装置から送信された前記ダウンリンク光信号を分岐する手段と、分岐した一方の前記ダウンリンク光信号を前記ダウンリンク無線信号へ変換する第２の光電気変換手段と、前記第２の光電気変換手段から出力された前記ダウンリンク無線信号から前記アップリンク無線信号を減算することによって多重無線信号を生成する第１の多重手段と、分岐した他方の前記ダウンリンク光信号を前記多重無線信号を用いて強度変調することによって、前記多重光信号を生成する第２の多重手段と、を備える光ファイバ無線アクセスシステム。
　（付記５）前記第１の光電気変換手段は、所定のオフセット強度を含む前記ダウンリンク光信号へ変換されるように電圧レベル及び振幅が設定された前記ダウンリンク無線信号を用いる、付記１乃至４のいずれか１項に記載の光ファイバ無線アクセスシステム。
　（付記６）基地局装置と第１および第２の光ファイバで接続された中央局装置であって、光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換する第１の光電気変換手段と、前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を、前記基地局装置においてアップリンク無線信号を用いて強度変調され、前記アップリンク無線信号と前記ダウンリンク無線信号とが多重された多重光信号から前記アップリンク無線信号を抽出する抽出手段と、を備える中央局装置。
　（付記７）中央局装置と第１および第２の光ファイバで接続された基地局装置であって、前記第１の光ファイバを経由して前記中央局装置から送信された、ダウンリンク光信号をアップリンク無線信号を用いて強度変調することによって、前記アップリンク無線信号と前記ダウンリンク光信号に含まれるダウンリンク無線信号とを多重した多重光信号を生成し、前記多重光信号を第２の光ファイバを経由して前記中央局装置へ送信する、基地局装置。
　（付記８）基地局装置と第１および第２の光ファイバで接続された中央局装置において用いられる信号抽出方法であって、光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換し、前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を、前記基地局装置においてアップリンク無線信号を用いて強度変調され、前記アップリンク無線信号と前記ダウンリンク無線信号とが多重された多重光信号を前記第２の光ファイバを経由して受信し、前記多重光信号から前記アップリンク無線信号を抽出する、抽出方法。
　（付記９）中央局装置と第１および第２の光ファイバで接続された基地局装置において用いられる通信方法であって、前記第１の光ファイバを経由して前記中央局装置から送信された、ダウンリンク光信号をアップリンク無線信号を用いて強度変調することによって、前記アップリンク無線信号と前記ダウンリンク光信号に含まれるダウンリンク無線信号とを多重した多重光信号を生成し、前記多重光信号を第２の光ファイバを経由して前記中央局装置へ送信する、通信方法。
　（付記１０）基地局装置と第１および第２の光ファイバで接続されたコンピュータに実行させるプログラムであって光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換し、前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を、前記基地局装置においてアップリンク無線信号を用いて強度変調され、前記アップリンク無線信号と前記ダウンリンク無線信号とが多重された多重光信号を前記第２の光ファイバを経由して受信し、前記多重光信号から前記アップリンク無線信号を抽出する、ことをコンピュータに実行させるプログラムを記録する非一時的なコンピュータ可読記録媒体。
　（付記１１）中央局装置と第１および第２の光ファイバで接続されたコンピュータに実行させるプログラムであって、前記第１の光ファイバを経由して前記中央局装置から送信された、ダウンリンク光信号をアップリンク無線信号を用いて強度変調することによって、前記アップリンク無線信号と前記ダウンリンク光信号に含まれるダウンリンク無線信号とを多重した多重光信号を生成し、前記多重光信号を第２の光ファイバを経由して前記中央局装置へ送信する、ことをコンピュータに実行させるプログラムを記録する非一時的なコンピュータ可読記録媒体。 (Supplementary note 1) In an optical fiber radio access system in which a central station apparatus and a base station apparatus are connected by first and second optical fibers, the central station apparatus converts an optical signal output from a light source into a downlink radio signal. The first photoelectric conversion means for converting the downlink radio signal into a downlink optical signal by performing intensity modulation using the signal, and the downlink transmitted to the base station apparatus via the first optical fiber. A light receiving means for receiving a multiplexed optical signal generated by intensity-modulating the link optical signal via the second optical fiber; an extracting means for extracting the uplink radio signal from the multiplexed optical signal; The base station apparatus uses the downlink radio signal transmitted from the central station apparatus via the first optical fiber as the uplink radio signal. By intensity modulation Te, the optical fiber wireless access system and a multiplexing means for generating the multiplexed optical signal obtained by multiplexing the uplink radio signal and the downlink radio signal.
(Supplementary note 2) The central station apparatus further includes second photoelectric conversion means for converting the multiplexed optical signal into a multiplexed radio signal, and the extraction means uses the comparator circuit to improve the up-conversion from the multiplexed radio signal. The optical fiber radio access system according to appendix 1, which extracts a link radio signal.
(Supplementary note 3) The central station apparatus further includes second photoelectric conversion means for converting the multiplexed optical signal into a multiplexed wireless signal, and the extracting means uses the subtracting circuit to reduce the downlink from the multiplexed wireless signal. The optical fiber radio access system according to appendix 1, wherein the uplink radio signal is extracted by subtracting a radio signal.
(Supplementary Note 4) In an optical fiber radio access system in which a central station device and a base station device are connected by first and second optical fibers, the central station device converts an optical signal output from a light source into a downlink radio signal. The first photoelectric conversion means for converting the downlink radio signal into a downlink optical signal by performing intensity modulation using the signal, and the downlink transmitted to the base station apparatus via the first optical fiber. Light receiving means for receiving a multiplexed optical signal generated by intensity-modulating a link optical signal via the second optical fiber, and the base station device passes through the first optical fiber. Means for branching the downlink optical signal transmitted from the central station apparatus, and second means for converting one of the branched downlink optical signals into the downlink radio signal. Electrical conversion means; first multiplexing means for generating a multiplexed radio signal by subtracting the uplink radio signal from the downlink radio signal output from the second photoelectric conversion means; And a second multiplexing means for generating the multiplexed optical signal by intensity-modulating the downlink optical signal using the multiplexed wireless signal.
(Additional remark 5) The said 1st photoelectric conversion means uses the said downlink radio signal by which the voltage level and the amplitude were set so that it might be converted into the said downlink optical signal containing predetermined | prescribed offset intensity | strength. 5. The optical fiber radio access system according to claim 1.
(Supplementary note 6) A central station apparatus connected to a base station apparatus through first and second optical fibers, wherein the optical signal output from the light source is intensity-modulated using a downlink radio signal, whereby the down A first photoelectric conversion means for converting a link radio signal into a downlink optical signal; and the downlink optical signal transmitted to the base station device via the first optical fiber is uploaded in the base station device. A central station apparatus comprising: extraction means for extracting the uplink radio signal from a multiplexed optical signal obtained by intensity modulation using a link radio signal and multiplexing the uplink radio signal and the downlink radio signal.
(Supplementary note 7) A downlink optical signal transmitted from the central station apparatus via the first optical fiber, which is a base station apparatus connected to the central station apparatus via the first and second optical fibers. Is modulated using an uplink radio signal to generate a multiplexed optical signal in which the uplink radio signal and the downlink radio signal included in the downlink optical signal are multiplexed, and the multiplexed optical signal is A base station apparatus that transmits to the central station apparatus via an optical fiber.
(Additional remark 8) It is a signal extraction method used in the central station apparatus connected with the base station apparatus with the 1st and 2nd optical fiber, Comprising: The optical signal output from a light source is intensity-modulated using a downlink radio signal By converting the downlink radio signal into the downlink optical signal and transmitting the downlink optical signal transmitted to the base station apparatus via the first optical fiber in the base station apparatus. A multiplexed optical signal that is intensity-modulated using a signal and multiplexed with the uplink radio signal and the downlink radio signal is received via the second optical fiber, and the uplink radio signal is received from the multiplexed optical signal. An extraction method for extracting a signal.
(Additional remark 9) It is the communication method used in the base station apparatus connected with the central station apparatus with the 1st and 2nd optical fiber, Comprising: It transmitted from the said central station apparatus via the said 1st optical fiber Generating a multiplexed optical signal obtained by multiplexing the uplink wireless signal and the downlink wireless signal included in the downlink optical signal by intensity-modulating the downlink optical signal using the uplink wireless signal; A communication method for transmitting an optical signal to the central station apparatus via a second optical fiber.
(Supplementary Note 10) A program to be executed by a computer connected to a base station device through first and second optical fibers, and by modulating the intensity of an optical signal output from a light source using a downlink radio signal, The downlink radio signal is converted into a downlink optical signal and transmitted to the base station apparatus via the first optical fiber, and the downlink optical signal is transmitted using the uplink radio signal in the base station apparatus. Receiving a multiplexed optical signal modulated and multiplexed with the uplink radio signal and the downlink radio signal via the second optical fiber, and extracting the uplink radio signal from the multiplexed optical signal; A non-transitory computer-readable recording medium that records a program that causes a computer to execute the above-described process.
(Supplementary Note 11) A downlink program, which is executed by a computer connected to a central office device via first and second optical fibers, transmitted from the central office device via the first optical fiber An optical signal is intensity-modulated using an uplink radio signal to generate a multiplexed optical signal in which the uplink radio signal and the downlink radio signal included in the downlink optical signal are multiplexed, and the multiplexed optical signal is A non-transitory computer-readable recording medium for recording a program for causing a computer to execute transmission to the central office device via a second optical fiber.
　この出願は、２０１５年２月２５日に出願された日本出願特願２０１５－０３５４４８を基礎とする優先権を主張し、その開示の全てをここに取り込む。 This application claims priority based on Japanese Patent Application No. 2015-035448 filed on February 25, 2015, the entire disclosure of which is incorporated herein.
　１　ＢＢＵ
　２　ＲＲＵ
　３　送受信部
　４　光源
　５　光変調器
　６　光変調器
　７　光伝送路
　８　光伝送路
　９　受光器
　１０　受光器
　１１　デュプレクサ
　１２　アンテナ
　１３　光カプラ
　２１　バンドパスフィルタ
　２２　コンパレータ
　２４　減算器
　２５　データ変換回路
　２６　アンプ
　２７　遅延回路
　２８　減算器
　１００　中央局装置
　１０１　光電気変換部
　１０２　受光部
　１０３　抽出部
　１１０　基地局装置
　１１１　多重部
　１２０　光ファイバ
　１３０　光ファイバ 1 BBU
2 RRU
DESCRIPTION OF SYMBOLS 3 Transmission / reception part 4 Light source 5 Optical modulator 6 Optical modulator 7 Optical transmission path 8 Optical transmission path 9 Optical receiver 10 Optical receiver 11 Duplexer 12 Antenna 13 Optical coupler 21 Band pass filter 22 Comparator 24 Subtractor 25 Data conversion circuit 26 Amplifier 27 Delay circuit 28 Subtractor 100 Central station apparatus 101 Photoelectric conversion section 102 Light receiving section 103 Extraction section 110 Base station apparatus 111 Multiplexing section 120 Optical fiber 130 Optical fiber

Claims (10)

  1. 　中央局装置と基地局装置とが第１および第２の光ファイバで接続された光ファイバ無線アクセスシステムであって、
    　前記中央局装置は、
    　光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換する第１の光電気変換手段と、　前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号が強度変調されたことによって生成された多重光信号を前記第２の光ファイバを経由して受信する受光手段と、
    　前記多重光信号からアップリンク無線信号を抽出する抽出手段と、を備え、
    　前記基地局装置は、
    　前記第１の光ファイバを経由して前記中央局装置から送信された前記ダウンリンク光信号を前記アップリンク無線信号を用いて強度変調することによって、前記アップリンク無線信号と前記ダウンリンク無線信号とを多重した前記多重光信号を生成する多重手段と、を備える光ファイバ無線アクセスシステム。     An optical fiber radio access system in which a central station device and a base station device are connected by first and second optical fibers,
    The central station device is
    A first photoelectric conversion means for converting the downlink radio signal into a downlink optical signal by intensity-modulating the optical signal output from the light source using the downlink radio signal; and the first optical fiber; A light receiving means for receiving, via the second optical fiber, a multiplexed optical signal generated by intensity modulation of the downlink optical signal transmitted to the base station device via,
    Extracting means for extracting an uplink radio signal from the multiplexed optical signal,
    The base station device
    By intensity-modulating the downlink optical signal transmitted from the central station apparatus via the first optical fiber using the uplink radio signal, the uplink radio signal and the downlink radio signal An optical fiber radio access system comprising: multiplexing means for generating the multiplexed optical signal that is multiplexed.
  2. 　前記中央局装置は、
    　前記多重光信号を多重無線信号へ変換する第２の光電気変換手段をさらに備え、
    　前記抽出手段は、
    　コンパレータ回路を用いることによって前記多重無線信号から前記アップリンク無線信号を抽出する、請求項１に記載の光ファイバ無線アクセスシステム。     The central station device is
    Further comprising second photoelectric conversion means for converting the multiplexed optical signal into a multiplexed radio signal;
    The extraction means includes
    The optical fiber radio access system according to claim 1, wherein the uplink radio signal is extracted from the multiplexed radio signal by using a comparator circuit.
  3. 　前記中央局装置は、
    　前記多重光信号を多重無線信号へ変換する第２の光電気変換手段をさらに備え、
    　前記抽出手段は、
    　減算回路を用いて前記多重無線信号から前記ダウンリンク無線信号を減算することによって、前記アップリンク無線信号を抽出する、請求項１に記載の光ファイバ無線アクセスシステム。     The central station device is
    Further comprising second photoelectric conversion means for converting the multiplexed optical signal into a multiplexed radio signal;
    The extraction means includes
    The optical fiber radio access system according to claim 1, wherein the uplink radio signal is extracted by subtracting the downlink radio signal from the multiplexed radio signal using a subtraction circuit.
  4. 　中央局装置と基地局装置とが第１および第２の光ファイバで接続された光ファイバ無線アクセスシステムであって、
    　前記中央局装置は、
    　光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換する第１の光電気変換手段と、　前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を強度変調することによって生成された多重光信号を前記第２の光ファイバを経由して受信する受光手段と、を備え、
    　前記基地局装置は、
    　前記第１の光ファイバを経由して前記中央局装置から送信された前記ダウンリンク光信号を分岐する手段と、
    　分岐した一方の前記ダウンリンク光信号を前記ダウンリンク無線信号へ変換する第２の光電気変換手段と、
    　アップリンク無線信号から、前記第２の光電気変換手段から出力された前記ダウンリンク無線信号を減算することによって多重無線信号を生成する減算手段と、
    　分岐した他方の前記ダウンリンク光信号を前記多重無線信号を用いて強度変調することによって、前記多重光信号を生成する多重手段と、を備える光ファイバ無線アクセスシステム。     An optical fiber radio access system in which a central station device and a base station device are connected by first and second optical fibers,
    The central station device is
    A first photoelectric conversion means for converting the downlink radio signal into a downlink optical signal by intensity-modulating the optical signal output from the light source using the downlink radio signal; and the first optical fiber; Light receiving means for receiving a multiplexed optical signal generated by intensity-modulating the downlink optical signal transmitted to the base station device via the second optical fiber,
    The base station device
    Means for branching the downlink optical signal transmitted from the central office device via the first optical fiber;
    Second photoelectric conversion means for converting one of the branched downlink optical signals into the downlink radio signal;
    Subtracting means for generating a multiplexed radio signal by subtracting the downlink radio signal output from the second photoelectric conversion means from the uplink radio signal;
    An optical fiber radio access system comprising: multiplexing means for generating the multiplexed optical signal by intensity-modulating the other branched downlink optical signal using the multiplexed radio signal.
  5. 　前記第１の光電気変換手段は、
    　所定のオフセット強度を含む前記ダウンリンク光信号へ変換されるように電圧レベル及び振幅が設定された前記ダウンリンク無線信号を用いる、請求項１乃至４のいずれか１項に記載の光ファイバ無線アクセスシステム。     The first photoelectric conversion means includes
    The optical fiber radio access according to any one of claims 1 to 4, wherein the downlink radio signal having a voltage level and an amplitude set to be converted into the downlink optical signal including a predetermined offset strength is used. system.
  6. 　基地局装置と第１および第２の光ファイバで接続された中央局装置であって、
    　光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換する第１の光電気変換手段と、　前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を、前記基地局装置においてアップリンク無線信号を用いて強度変調され、前記アップリンク無線信号と前記ダウンリンク無線信号とが多重された多重光信号から前記アップリンク無線信号を抽出する抽出手段と、を備える中央局装置。     A central station apparatus connected to a base station apparatus by first and second optical fibers,
    A first photoelectric conversion means for converting the downlink radio signal into a downlink optical signal by intensity-modulating the optical signal output from the light source using the downlink radio signal; and the first optical fiber; Multiplexing in which the downlink optical signal transmitted to the base station apparatus is intensity-modulated using an uplink radio signal in the base station apparatus, and the uplink radio signal and the downlink radio signal are multiplexed. A central station apparatus comprising: extraction means for extracting the uplink radio signal from an optical signal.
  7. 　中央局装置と第１および第２の光ファイバで接続された基地局装置であって、
    　前記第１の光ファイバを経由して前記中央局装置から送信された、ダウンリンク光信号をアップリンク無線信号を用いて強度変調することによって、前記アップリンク無線信号と前記ダウンリンク光信号に含まれるダウンリンク無線信号とを多重した多重光信号を生成し、前記多重光信号を第２の光ファイバを経由して前記中央局装置へ送信する、基地局装置。     A base station apparatus connected to the central station apparatus by first and second optical fibers,
    Included in the uplink radio signal and the downlink optical signal by intensity-modulating the downlink optical signal transmitted from the central station apparatus via the first optical fiber using the uplink radio signal A base station apparatus that generates a multiplexed optical signal that is multiplexed with a downlink radio signal and transmits the multiplexed optical signal to the central station apparatus via a second optical fiber.
  8. 　基地局装置と第１および第２の光ファイバで接続された中央局装置において用いられる信号抽出方法であって、
    　光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換し、
    　前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を、前記基地局装置においてアップリンク無線信号を用いて強度変調され、前記アップリンク無線信号と前記ダウンリンク無線信号とが多重された多重光信号を前記第２の光ファイバを経由して受信し、
    　前記多重光信号から前記アップリンク無線信号を抽出する、抽出方法。     A signal extraction method used in a central station apparatus connected to a base station apparatus through first and second optical fibers,
    By converting the intensity of the optical signal output from the light source using the downlink radio signal, the downlink radio signal is converted into a downlink optical signal,
    The downlink optical signal transmitted to the base station apparatus via the first optical fiber is intensity-modulated using an uplink radio signal in the base station apparatus, and the uplink radio signal and the downlink radio are transmitted. A multiplexed optical signal multiplexed with the signal is received via the second optical fiber;
    An extraction method for extracting the uplink radio signal from the multiplexed optical signal.
  9. 　中央局装置と第１および第２の光ファイバで接続された基地局装置において用いられる通信方法であって、
    　前記第１の光ファイバを経由して前記中央局装置から送信された、ダウンリンク光信号をアップリンク無線信号を用いて強度変調することによって、前記アップリンク無線信号と前記ダウンリンク光信号に含まれるダウンリンク無線信号とを多重した多重光信号を生成し、
    　前記多重光信号を第２の光ファイバを経由して前記中央局装置へ送信する、通信方法。     A communication method used in a base station apparatus connected to a central station apparatus through first and second optical fibers,
    Included in the uplink radio signal and the downlink optical signal by intensity-modulating the downlink optical signal transmitted from the central station apparatus via the first optical fiber using the uplink radio signal A multiplexed optical signal multiplexed with a downlink radio signal
    A communication method for transmitting the multiplexed optical signal to the central station device via a second optical fiber.
  10. 　基地局装置と第１および第２の光ファイバで接続されたコンピュータに実行させるプログラムであって、
    　光源から出力される光信号をダウンリンク無線信号を用いて強度変調することによって、前記ダウンリンク無線信号をダウンリンク光信号へ変換し、
    　前記第１の光ファイバを経由して前記基地局装置へ送信した前記ダウンリンク光信号を、前記基地局装置においてアップリンク無線信号を用いて強度変調され、前記アップリンク無線信号と前記ダウンリンク無線信号とが多重された多重光信号を前記第２の光ファイバを経由して受信し、
    　前記多重光信号から前記アップリンク無線信号を抽出する、ことをコンピュータに実行させるプログラムを記録する非一時的なコンピュータ可読記録媒体。     A program to be executed by a computer connected to a base station device through first and second optical fibers,
    By converting the intensity of the optical signal output from the light source using the downlink radio signal, the downlink radio signal is converted into a downlink optical signal,
    The downlink optical signal transmitted to the base station apparatus via the first optical fiber is intensity-modulated using an uplink radio signal in the base station apparatus, and the uplink radio signal and the downlink radio are transmitted. A multiplexed optical signal multiplexed with the signal is received via the second optical fiber;
    A non-transitory computer-readable recording medium for recording a program for causing a computer to extract the uplink radio signal from the multiplexed optical signal.
PCT/JP2016/000805 2015-02-25 2016-02-17 Optical fiber wireless access system, central station device, base station device, extraction method and communication method WO2016136188A1 (en)

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