JP2007067663A - Optical-wireless fusion communications system and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical-wireless fusion communications system for incoming/outgoing bidirectional communication by a storage station and a wireless base station, using an inexpensive and simple configuration. <P>SOLUTION: An optical signal from a first single spectrum light source 102 is branched in two in the storage station 100, and one is modulated by a carrier wave restriction both-side wave band with the use of the carrier wave signal of half value of a frequency in an outgoing wireless signal, and modulated by outgoing transmission data so as to be multiplexed with the other and transmitted to the wireless base station. The optical signal received is branched in two in the wireless base station 300; the outgoing wireless signal obtained by receiving one signal is transmitted to a wireless terminal 400, and the other is modulated by an incoming wireless signal from the wireless terminal 400 and returned to the storage station 100. The storage station 100 multiplexes the received modulation optical signal with a signal which is obtained by combining the optical signals from second and third single spectrum light sources 103, 104 with orthogonal polarized wave, performs square-law detection, and then reproduces uplink transmission data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, in the downlink, the optical signal transmitted from the accommodating station is converted into a radio signal by the radio base station and transmitted to the radio terminal, and in the uplink, the high-frequency radio signal received by the radio base station is converted into an optical signal. The present invention relates to an optical-radio fusion communication system and an optical-wireless fusion communication method for transmission to a receiving station.

  FIG. 21 shows an example of a conventional optical-radio fusion communication system including a accommodating station, a radio base station, and a radio terminal. FIG. 22 shows an example of the frequency spectrum of each signal in the conventional optical-radio fusion communication system. Is shown.

Conventionally, in the optical transmitter 1 in the accommodation station 0, the output optical signal 0a of the single spectrum light source 2 is modulated by the optical modulator 7 and the electric carrier signal from the electric oscillator 3 is modulated by the downstream transmission data by the electric modulator 5. Optical modulation is performed by the electric signal obtained by adding the downstream radio signal 0b and the electric carrier signal 0c having the frequency f _LO by the electric adder 6 to generate a modulated optical signal 0d. Further, an optical signal 0e obtained by removing the upper sideband signal (or lower sideband signal) of the modulated optical signal 0d by the optical filter 8 is transmitted to the radio base station 9 through the optical transmission line.

  In the radio base station 9, the optical signal 0 e received and amplified by the optical amplifier 10 is branched into two by the optical splitter 11, and one output optical signal is converted into an electrical signal by the optical receiver 12, and then the desired signal is output by the filter 13 The downlink radio signal 0f (equal to 0d) is extracted and transmitted from the antenna 14 to the radio terminal 19. The other output optical signal of the optical splitter 11 is optically modulated by the optical modulator 16 with the received upstream radio signal 0g, and then only a desired optical signal (0h) is extracted by the optical filter 17. And is transmitted to the optical receiver 25 in the accommodating station 0 through the optical transmission line.

  In the optical receiver 25, the optical signal 0h transmitted from the radio base station 9 is converted into the electric signal 0i by the light receiver 26 and passed through the filter 27 to obtain the intermediate frequency signal 0j modulated by the upstream transmission data. be able to.

As described above, in the conventional technique, the light source and the optical modulator can be shared in the uplink / downlink, so that a low-cost system can be constructed. In addition, since the millimeter wave down-conversion is performed in the optical region, it is not necessary to prepare millimeter wave band parts in the optical receiver, so that the configuration of the entire system can be simplified.
Japanese Patent Laid-Open No. 2001-103015 “Millimeter-Wave Wireless Bidirectional Transmission Method and Millimeter-Wave Wireless Bidirectional Transmission Device”

  In the conventional examples shown in FIGS. 21 and 22, when a plurality of optical transmitters are provided in the accommodating station corresponding to a plurality of radio base stations, the optical modulation having the frequency band of the radio signal in each optical transmitter. It is necessary to prepare a vessel, and the configuration becomes complicated. In particular, when transmitting a broadband signal, it is expected to use a millimeter wave band capable of securing a wide signal band as a frequency of a radio signal. However, an optical modulator having such a high frequency band is expensive. Further, in the uplink, in order to compensate for the loss due to fiber transmission and the insertion loss of the optical modulator in the radio base station, an optical amplifier is required for each radio base station or optical receiver, and the configuration becomes complicated and expensive. .

  The present invention is made in such a background, and it is possible to realize high-sensitivity optical reception with an optical transceiver having a low-cost and simple configuration in the uplink while sharing a light source in the uplink / downlink. An object of the present invention is to provide an optical-wireless fusion communication system and method.

(First invention)
The accommodation station includes an optical signal generator, an optical transmitter, and an optical receiver, and the optical transmitter is configured to transmit a downlink optical radio signal modulated with downlink transmission data to the radio base station via an optical transmission path, and an uplink An optical carrier signal is transmitted, and the radio base station bifurcates the received optical signal with an optical branching device, and receives a downlink optical signal (frequency f) obtained by receiving one output optical signal of the optical branching device. _RF-d ) to the wireless terminal, a radio signal modulated with uplink transmission data (frequency f _RF-u ) is received, and the other output optical signal of the optical branching device is received with the received uplink radio signal. Optical-wireless communication that performs optical modulation and transmits the modulated optical signal to the accommodating station via an optical transmission line, and the optical receiver receives the modulated optical signal, detects it, and reproduces the upstream transmission data. In the system, the optical signal generator, optical transmitter, and optical receiver are each Is the next of such a configuration.

The optical signal generator
A first single spectrum light source that outputs a first single spectrum optical signal (center frequency f _c1 ) and a second single that outputs a second single spectrum optical signal (center frequency f _c2 ) A spectral light source, a third single spectral light source that outputs a third single spectral optical signal (center frequency f _c3 ), an optical splitter that splits the first single spectral optical signal into two branches, One output optical signal of the optical splitter is subjected to optical carrier suppression double-sideband modulation with an electric carrier signal having a half value (f _RF-d / 2) of a desired downlink radio signal frequency f _RF-d. The polarization directions of the optical modulator, the polarization direction and the light intensity of the second single spectrum optical signal, and the polarization direction and the light intensity of the third single spectrum optical signal are orthogonal to each other. And adjust to equal light intensity and synthesize two waves with orthogonal polarization. And a polarization combining means for outputting as a polarization combiner optical signals.

The center frequencies f _c1 , f _c2 , and f _c3 of the first, second, and third single spectrum optical signals are set to the frequency f _RF-u and the predetermined intermediate frequencies f _IF1 and f _IF2 of the uplink radio signal, respectively. for,
| F _c1 −f _c2 | = f _RF−u ± f _{IF1
| F c1 -f c3 | = f} RF-u ± f IF2
It is controlled to become.

  The optical signal generator inputs the carrier-suppressed double-sideband modulated optical signal to the optical transmitter, and inputs the other output optical signal of the optical splitter to the optical transmitter as the uplink optical carrier signal The polarization combined optical signal is output to the optical receiver.

  The optical transmitter includes an optical modulator that optically modulates a carrier-suppressed double-sideband modulated optical signal with downstream transmission data, out of two input optical signals, and outputs the optical signal output from the optical modulator as downstream light In this configuration, an uplink optical carrier signal and an optical multiplexer are combined as a radio signal and then transmitted to a radio base station.

The optical receiver includes an optical multiplexer that combines the modulated optical signal transmitted from the radio base station and the polarization combined optical signal output from the optical signal generator, and an optical signal that is combined by the optical multiplexer. It receives a light receiver for outputting an electric signal of intermediate frequency f _IF1, f _IF2, an electric detector for detecting the electrical signals of an intermediate frequency f _IF1, f _IF2 outputted from the light receiver, the output of the electrical detector A low-pass filter that performs low-pass filtering of the signal and outputs upstream transmission data.

  According to the first invention, the optical signal generation unit branches the first single-spectrum optical signal, inputs one to the optical transmitter as an optical carrier signal for uplink, and the other is optical carrier suppression. After applying double-sideband modulation, it is input to the optical transmitter, and a polarization-combined optical signal obtained by orthogonally combining two waves of the second single-spectrum optical signal and the third single-spectrum optical signal is output as an optical signal. Output to the optical receiver as a local signal. As a result, the optical signal generator can simultaneously generate the downlink optical radio signal, the uplink optical carrier signal, and the optical local signal used for optical heterodyne detection. In addition, since the optical signal generator performs frequency stabilization control based on an unmodulated and non-attenuated optical signal, it is based on a modulated optical signal attenuated due to transmission loss in an optical receiver based on the conventional high-sensitivity optical reception method. Compared with the case where the frequency stabilization control is performed, the frequency stabilization control can be easily performed.

An electric field E _{opt-c of} an optical signal to be transmitted to the radio base station (combined optical signal of downlink optical radio signal and uplink optical carrier signal) and an electric field E _opt- of the polarization combined optical signal output to the optical receiver Each _LO can be expressed as:

E _opt-c = A _d a _d cos (2π (f _c1 −f _RF−d / 2) t + φ ₁ (t))
+ A _d a _d cos (2π (f _c1 + f _RF−d / 2) t + φ ₁ (t))
+ A _u cos (2πf _c1 t + φ ₁ (t)) (1)
_{E opt-LO = A LO cos} (2πf c2 t + φ 2 (t))
+ A _LO cos (2πf _c3 t + φ ₃ (t)) (2)
Here, A _d , A _u , and A _LO are electric field amplitudes, φ (t) is a phase noise component of an output optical signal of a single spectrum light source, and a _d is downlink transmission data (binary digital signal: 0, 1). To do. Also, the first and second terms in equation (1) represent downstream optical wireless signals, the third term represents uplink optical carrier signals, and the first and second terms on the right side of equation (2). The terms have equal polarization directions with orthogonal polarization directions.

In the radio base station, the optical signal (Equation (1)) transmitted from the optical transmitter is branched into two by the optical splitter, and the downlink radio signal obtained by receiving one of the output optical signals is transmitted to the radio terminal. Send. The electric field E _RF-d of the downlink radio signal can be expressed as follows.

^{_{E RF-d α A d 2}} a d (cos2πf RF-d (t + T)) ... (3)
In the above formula, T represents the time required for optical transmission of the optical signal between the accommodating station and the radio base station.

Here, since the downstream optical wireless signal is generated by modulating the single optical signal with the carrier-suppressed double-sideband, the phase noise (φ ₁ (t)) of the optical signal at the time of light reception at the wireless base station It can be seen that a downlink radio signal having a very stable frequency is generated.

The other output optical signal of the optical branching device is optically modulated with the wireless signal transmitted from the wireless terminal and then transmitted to the optical receiver. The electric field E _opt-mod of the modulated optical signal transmitted to the optical receiver by binary digital amplitude modulation can be expressed as follows:
E _opt-mod ∝ (1 + ma _u cos (2πf _RF-u t))
・ [A _d a _d cos (2π (f _c1 −f _RF−d / 2) (t + T) + φ ₁ (t + T))
+ A _d a _d cos (2π (f _c1 + f _RF−d / 2) (t + T) + φ ₁ (t + T))
+ A _u cos (2πf _c1 (t + T) + φ ₁ (t + T))] (4)
Here, m represents the degree of optical modulation, and a _u represents uplink transmission data (binary digital signal: 0, 1).

  In the optical receiver, the polarization combined optical signal (formula (2)) output from the optical signal generator and the modulated optical signal (formula (4)) transmitted from the radio base station are combined and then received. Square detection with the instrument.

The electric field E _opt-co of the combined optical signal can be expressed as follows.

E _opt-co ∝ A _LO cos (2πf _c2 t + φ ₂ (t))
+ A _LO cos (2πf _c3 t + φ ₃ (t))
+ (1 / γ) (1 + ma _u cos (2πf _RF-u t))
・ [A _d a _d cos (2π (f _c1 −f _RF−d / 2) (t + 2T) + φ ₁ (t + 2T))
+ A _d a _d cos (2π (f _c1 + f _RF−d / 2) (t + 2T) + φ ₁ (t + 2T))
+ A _u cos (2πf _c1 (t + 2T) + φ ₁ (t + 2T))] (5)
Here, γ represents the total loss such as optical transmission loss between the radio base station and the optical receiver and insertion loss of the optical modulator in the radio base station, and γ >> 1.

  The optical signals of the first term and the second term on the right side of the equation (5) are directly input from the optical signal generator to the optical receiver, and thus have no loss and have sufficient light intensity. For this reason, the optical signal of the formula (5) is square-detected by a photoreceiver, so that the modulated optical signal (formula (4)) transmitted from the radio base station is obtained in the same manner as the optical heterodyne detection known as a high sensitivity optical reception method. ) Can be received with high sensitivity.

The electric field E _IF of the electric signal having two intermediate frequencies f _IF1 and f _IF2 output from the light receiver can be expressed as follows.

E _IF = Ga _u A _u A _LO [cos θ · cos (2πf _IF1 t + ψ ₁ ) + sin θ · cos (2πf _IF2 t + ψ ₂ )]
However, ψ ₁ = ± [4πf _c1 T + φ ₁ (t + 2T) −φ ₂ (t)]
ψ ₂ = ± [4πf _c1 T + φ ₁ (t + 2T) −φ ₃ (t)]
(6)
Here, G is a coefficient depending on the gain of the optical heterodyne detection, ψ ₁ and ψ ₂ are phase components of electric signals of the intermediate frequencies f _IF1 and f _IF2 , and θ is a modulated optical signal transmitted from the radio base station. The angle between the polarization direction of (Expression (4)) and the polarization direction of the optical signal represented by the first term of Expression (2) among the polarization-combined optical signals output from the optical signal generator .

  Since the optical signal generator controls the center frequency of the first, second and third single spectrum optical signals to be a set value, the optical receiver has a complicated configuration of radio frequency band components. In addition, a stable intermediate frequency signal can be obtained without using an intermediate frequency stabilization circuit.

The electric field E _{BB of the} electric signal obtained through the low-pass filter after detecting the electric signals of the two intermediate frequencies f _IF1 and f _IF2 can be expressed as follows.

E _BB ∝G ² a _u ² A _u ² A _LO ² (cos ² θ + sin ² θ) = G ² a _u A _u ² A _LO ² (7)
Here, since the polarization combined optical signal (formula (2)) output from the optical signal generator has the same optical intensity as the orthogonal polarization directions, the output signal intensity of the low-pass filter is the radio base station. It turns out that it is insensitive to the modulated optical signal (Equation (4)) transmitted from.

(Second invention)
The accommodation station includes an optical signal generator, an optical transmitter, and an optical receiver, and the optical transmitter is configured to transmit a downlink optical radio signal modulated with downlink transmission data to the radio base station via an optical transmission path, and an uplink An optical carrier signal is transmitted, and the radio base station bifurcates the received optical signal with an optical branching device, and receives a downlink optical signal (frequency f) obtained by receiving one output optical signal of the optical branching device. _RF-d ) to the wireless terminal, a radio signal modulated with uplink transmission data (frequency f _RF-u ) is received, and the other output optical signal of the optical branching device is received with the received uplink radio signal. Optical-wireless communication that performs optical modulation and transmits the modulated optical signal to the accommodating station via an optical transmission line, and the optical receiver receives the modulated optical signal, detects it, and reproduces the upstream transmission data. In the system, the optical signal generator, optical transmitter, and optical receiver are each Is the next of such a configuration.

The optical signal generator
A first single spectrum light source that outputs a first single spectrum optical signal (center frequency f _c1 ) and a second single that outputs a second single spectrum optical signal (center frequency f _c2 ) A spectral light source, a third single spectral light source that outputs a third single spectral optical signal (center frequency f _c3 ), an optical splitter that splits the first single spectral optical signal into two branches, One output optical signal of the optical splitter is subjected to optical carrier suppression double-sideband modulation with an electric carrier signal having a half value (f _RF-d / 2) of a desired downlink radio signal frequency f _RF-d. The polarization directions of the optical modulator, the polarization direction and the light intensity of the second single spectrum optical signal, and the polarization direction and the light intensity of the third single spectrum optical signal are orthogonal to each other. And adjust to equal light intensity and synthesize two waves with orthogonal polarization. And a polarization combining means for outputting as a polarization combiner optical signals.

The center frequencies f _c1 , f _c2 , and f _c3 of the first, second, and third single spectrum optical signals are set to the frequency f _RF-u and the predetermined intermediate frequencies f _IF1 and f _IF2 of the uplink radio signal, respectively. for,
| F _c1 −f _c2 | = f _RF−u ± f _{IF1
| F c1 -f c3 | = f} RF-u ± f IF2
It is controlled to become.

  The optical signal generation unit inputs the carrier-suppressed double-sideband modulated optical signal to the optical transmitter, inputs the polarization combined optical signal to the optical transmitter as the uplink optical carrier signal, and The other output optical signal of the receiver is output to the optical receiver.

  The optical transmitter includes an optical modulator that optically modulates a carrier-suppressed double-sideband modulated optical signal with downstream transmission data, out of two input optical signals, and outputs the optical signal output from the optical modulator as downstream light In this configuration, an uplink optical carrier signal and an optical multiplexer are combined as a radio signal and then transmitted to a radio base station.

The optical receiver includes an optical multiplexer that multiplexes the modulated optical signal transmitted from the radio base station and the single-spectrum optical signal output from the optical signal generator, and the light that is combined by the optical multiplexer. receiving a signal, and a photodetector for outputting an electrical signal having the intermediate frequency f _IF1, f _IF2, an electric detector for detecting the electrical signals of an intermediate frequency f _IF1, f _IF2 outputted from the light receiver, the electrical detector A low-pass filter for low-pass filtering the output signal and outputting upstream transmission data.

  According to the second invention, the optical signal generator branches the first single-spectrum optical signal, outputs one as an optical local signal to the optical receiver, and the other is an optical carrier-suppressed double sideband. After being modulated, the signal is input to the optical transmitter, and the polarization-combined optical signal obtained by orthogonally combining two waves of the second single-spectrum optical signal and the third single-spectrum optical signal is used as the uplink light. The carrier wave signal is input to the optical transmitter. As a result, the optical signal generator can simultaneously generate the downlink optical radio signal, the uplink optical carrier signal, and the optical local signal used for optical heterodyne detection. In addition, since the optical signal generator performs frequency stabilization control based on an unmodulated and non-attenuated optical signal, it is based on a modulated optical signal attenuated due to transmission loss in an optical receiver based on the conventional high-sensitivity optical reception method. Compared with the case where the frequency stabilization control is performed, the frequency stabilization control can be easily performed.

An electric field E _{opt-c of} an optical signal to be transmitted to the radio base station (combined optical signal of downlink optical radio signal and uplink optical carrier signal) and an electric field E _opt- of the polarization combined optical signal output to the optical receiver Each _LO can be expressed as:

E _opt-c = A _d a _d cos (2π (f _c1 −f _RF−d / 2) t + φ ₁ (t))
+ A _d a _d cos (2π (f _c1 + f _RF−d / 2) t + φ ₁ (t))
+ A _u cos (2πf _c2 t + φ ₂ (t))
+ A _u cos (2πf _c3 t + φ ₃ (t)) (8)
E _opt-LO = A _LO cos (2πf _c1 t + φ ₁ (t)) (9)
Here, A _d , A _u , and A _LO are electric field amplitudes, φ (t) is a phase noise component of an output optical signal of a single spectrum light source, and a _d is downlink transmission data (binary digital signal: 0, 1). To do. Also, the first and second terms in equation (8) represent downstream optical wireless signals, and the third and fourth terms represent uplink optical carrier signals, which have polarization directions orthogonal to each other. , Are of equal amplitude.

In the radio base station, the optical signal (Equation (8)) transmitted from the optical transmitter is branched into two by the optical splitter, and the downlink radio signal obtained by receiving one of the output optical signals is transmitted to the radio terminal. Send. The electric field E _RF-d of the downlink radio signal can be expressed as follows.

^{_{E RF-d α A d 2}} a d (cos2πf RF-d (t + T)) ... (10)
In the above formula, T represents the time required for optical transmission of the optical signal between the accommodating station and the radio base station.

Here, since the downstream optical wireless signal is generated by modulating the single optical signal with the carrier-suppressed double-sideband, the phase noise (φ ₁ (t)) of the optical signal at the time of light reception at the wireless base station It can be seen that a downlink radio signal having a very stable frequency is generated.

The other output optical signal of the optical branching device is optically modulated with the wireless signal transmitted from the wireless terminal and then transmitted to the optical receiver. The electric field E _opt-mod of the modulated optical signal transmitted to the optical receiver by binary digital amplitude modulation can be expressed as follows.

E _opt-mod ∝ (1 + ma _u cos (2πf _RF-u t))
・ [A _d a _d cos (2π (f _c1 −f _RF−d / 2) (t + T) + φ ₁ (t + T))
+ A _d a _d cos (2π (f _c1 + f _RF−d / 2) (t + T) + φ ₁ (t + T))
_{+ A u cos (2πf c2 (} t + T) + φ 2 (t + T))
_{+ A u cos (2πf c3 (} t + T) + φ 3 (t + T))] ... (11)
Here, m represents the degree of optical modulation, and a _u represents uplink transmission data (binary digital signal: 0, 1).

  In the optical receiver, after combining the single-spectrum optical signal (formula (9)) output from the optical signal generator and the modulated optical signal (formula (11)) transmitted from the radio base station, Square detection with a receiver.

The electric field E _opt-co of the combined optical signal can be expressed as follows.

E _opt-co ∝ A _LO cos (2πf _c1 t + φ ₁ (t))
+ (1 / γ) (1 + ma _u cos (2πf _RF-u t))
・ [A _d a _d cos (2π (f _c1 −f _RF−d / 2) (t + 2T) + φ ₁ (t + 2T))
+ A _d a _d cos (2π (f _c1 + f _RF−d / 2) (t + 2T) + φ ₁ (t + 2T))
_{+ A u cos (2πf c2 (} t + 2T) + φ 2 (t + 2T))
+ A _u cos (2πf _c3 (t + 2T) + φ ₃ (t + 2T))] (12)
Here, γ represents the total loss such as optical transmission loss between the radio base station and the optical receiver and insertion loss of the optical modulator in the radio base station, and γ >> 1.

  The optical signal of the first term on the right side of the equation (12) is directly input from the optical signal generator to the optical receiver, and thus has no loss and has sufficient light intensity. For this reason, the optical signal of the equation (12) is square-detected by the light receiver, and the modulated optical signal (the equation (11) is transmitted from the radio base station as in the case of the optical heterodyne detection known as the high-sensitivity optical reception method). ) Can be received with high sensitivity.

The electric field E _IF of the electric signal having two intermediate frequencies f _IF1 and f _IF2 output from the light receiver can be expressed as follows.

E _IF = Ga _u A _u A _LO [cos θ · cos (2πf _IF1 t + ψ ₁ ) + sin θ · cos (2πf _IF2 t + ψ ₂ )]
However, ψ ₁ = ± [4πf _c1 T + φ ₁ (t + 2T) −φ ₂ (t)]
ψ ₂ = ± [4πf _c1 T + φ ₁ (t + 2T) −φ ₃ (t)]
... (13)
Here, G is a coefficient depending on the gain of the optical heterodyne detection, ψ ₁ and ψ ₂ are phase components of electric signals of the intermediate frequencies f _IF1 and f _IF2 , and θ is a modulated optical signal transmitted from the radio base station. (Equation (11)) between the polarization direction of the optical signal represented by the third term and the polarization direction of the single-spectrum optical signal (Equation (9)) output from the optical signal generator. Represents the angle of.

  Since the optical signal generator controls the center frequency of the first, second and third single spectrum optical signals to be a set value, the optical receiver has a complicated configuration of radio frequency band components. In addition, a stable intermediate frequency signal can be obtained without using an intermediate frequency stabilization circuit.

The electric field E _{BB of the} electric signal obtained through the low-pass filter after detecting the electric signals of the two intermediate frequencies f _IF1 and f _IF2 can be expressed as follows.

E _BB ∝G ² a _u ² A _u ² A _LO ² (cos ² θ + sin ² θ) = G ² a _u A _u ² A _LO ² (14)
Here, since the polarization-combined optical signal (the third term and the fourth term in the equation (8)) input from the optical signal generation unit to the optical transmitter has light intensity equal to the orthogonal polarization direction, the low It can be seen that the output signal strength of the diafiltration filter is insensitive to the modulated optical signal (Equation (11)) transmitted from the radio base station.

(Third invention)
3rd invention shows another structure of the optical receiver in the optical-radio fusion communication system of 1st or 2nd invention.

In the optical receiver, instead of the electric detector and the low-pass filter in the optical receiver in the first or second invention, an electric signal of the intermediate frequency f _{IF1 and} an electric signal of the intermediate frequency f _IF2 output from the light receiver. , A first electric detector and a second electric detector for detecting the electric signal of the intermediate frequency f _{IF1 and} the electric signal of the intermediate frequency f _IF2 output from the filter, respectively, and the first electric detection And an electrical adder for adding the output signal of the second electrical detector and the output signal of the second electrical detector and outputting uplink transmission data.

In the optical receiver according to the third aspect of the invention, by separating the electric signals of the intermediate frequencies f _IF1 and f _IF2 of the equation (6) or (13) with a filter, the two intermediate frequencies f _IF1 and f _IF2 of the following equation are obtained. Electrical signals E _IF1 and E _IF2 are obtained.

E _IF1 = Ga _u A _u A _LO cos θ · cos (2πf _IF1 t + ψ ₁ ) (15)
E _IF2 = Ga _u A _u A _LO cos θ · cos (2πf _IF2 t + ψ ₂ ) (16)
The electric signals of the intermediate frequencies f _IF1 and f _IF2 are respectively subjected to envelope detection, and the obtained electric signals are added by an electric adder. The electric field E _{BB of the} electric signal obtained by the electric adder can be expressed as follows.

E _BB ∝G ² a _u ² A _u ² A _LO ² (cos ² θ + sin ² θ) = G ² a _u A _u ² A _LO ² (17)
Here, in the first invention, the polarization combined optical signal (formula (2)) output from the optical signal generator to the optical receiver has the same light intensity as the orthogonal polarization directions, and the second invention Then, since the optical carrier signal for uplink transmitted from the optical signal generator to the radio base station (the third term and the fourth term in the equation (8)) has the same optical intensity as the polarization directions orthogonal to each other, It can be seen that the output of the electrical adder of the optical receiver in the invention is insensitive to the polarization direction of the modulated optical signal (Equation (4), Equation (11)) transmitted from the radio base station.

  As described above, according to the third invention, in the optical receiver, without using the radio frequency band component, the intermediate frequency stabilization circuit, and the polarization diversity circuit, one light receiver and two High-sensitivity light reception is possible with a simple configuration comprising an electric detector.

(Fourth invention)
4th invention shows another structure of the optical receiver in the optical-radio fusion communication system of 1st or 2nd invention.

In the optical receiver, instead of the electric detector and the low-pass filter in the optical receiver in the first or second invention, an electric signal of the intermediate frequency f _{IF1 and} an electric signal of the intermediate frequency f _IF2 output from the light receiver. , A first electric detector and a second electric detector for detecting the electric signal of the intermediate frequency f _{IF1 and} the electric signal of the intermediate frequency f _IF2 output from the filter, respectively, and the first electric detection And a phase adjustment adder that outputs the transmission data by adding the phases of the output signal of the detector and the output signal of the second electric detector in alignment.

  In the optical receiver according to the fourth invention, similarly to the optical receiver according to the third invention, it is possible to obtain a received signal with a constant output insensitive to the polarization direction of the modulated optical signal transmitted from the radio base station. The following functions are added as well as possible. By aligning and adding the phases of the output signal of the first electric detector and the output signal of the second electric detector, the output signal of the first electric detector and the second electric detector are distributed due to dispersion of the optical transmission line. A time difference generated between the output signal of the detector and the detector can be compensated.

  As described above, according to the fourth invention, high-sensitivity light reception is possible as in the third invention, and the output signal of the first electric detector and the second electric signal are influenced by the dispersion of the optical transmission line. By compensating for the time difference that occurs with the output signal of the detector, optical reception that is not affected by dispersion can be realized. As in the first aspect of the invention, an optical transmitter transmits a single-wave optical signal (the third term of equation (1)) as an uplink optical carrier signal to the radio base station, and the radio base station When a modulated optical signal (formula (4)) is transmitted to the optical receiver, the influence of dispersion of the optical transmission path appears on the modulated optical signal having two sideband components. Further, as in the second aspect of the invention, a two-wave polarization combined optical signal (the third and fourth terms in equation (8)) is transmitted from the optical transmitter to the radio base station as an optical carrier signal for uplink. When a modulated optical signal (formula (11)) is transmitted from the radio base station to the optical receiver, the influence of dispersion of the optical transmission path appears on both optical signals.

(Fifth invention)
In a fifth aspect of the optical-wireless communication system according to the first aspect, the fifth invention transmits a plurality of radio base stations and a downlink optical radio signal and an uplink optical carrier signal to the plurality of radio base stations to the accommodating station, respectively. The optical signal generator includes a plurality of optical transmitters and a plurality of optical receivers that respectively receive modulated optical signals transmitted from a plurality of radio base stations, and the optical signal generator branches the carrier-suppressed double-sideband modulated optical signals into a plurality The first optical branching device that is input to each of the plurality of optical transmitters, and the other output optical signal of the optical branching device are branched into a plurality of signals and input to the plurality of optical transmitters as optical carrier signals for the uplink, respectively. And a third optical splitter that branches the polarization-multiplexed optical signal into a plurality of signals and outputs them to the plurality of optical receivers.

  According to the fifth invention, it is not necessary to use radio frequency band components, an intermediate frequency stabilization circuit, and a polarization diversity circuit in all the optical receivers, and the configuration of the entire system can be greatly simplified.

(Sixth invention)
In a sixth aspect of the present invention, there is provided the optical-wireless communication system according to the second aspect, wherein a plurality of radio base stations and a downlink optical radio signal and an uplink optical carrier signal are respectively transmitted to a plurality of radio base stations to a receiving station. A plurality of optical transmitters and a plurality of optical receivers that respectively receive the modulated optical signals transmitted from the plurality of radio base stations, and the optical signal generator divides the polarization multiplexed optical signal into a plurality of A first optical splitter that is input to a plurality of optical transmitters as an optical carrier signal for a link, and a second optical that is split into a plurality of carrier-suppressed double sideband modulated optical signals and is input to a plurality of optical transmitters. A branching device, and a third optical branching device that branches the other output optical signal of the optical branching device into a plurality of signals and outputs them to the optical receiver.

  According to the sixth invention, it is not necessary to use radio frequency band components, an intermediate frequency stabilization circuit, and a polarization diversity circuit in all optical receivers, and the configuration of the entire system can be greatly simplified.

(Seventh invention)
According to a seventh aspect of the present invention, in the optical-wireless fusion communication system according to any one of the first to sixth aspects, the wireless base station includes an optical branching unit that splits the received optical signal into two branches, and one of the optical branching units. The received optical signal instead of the optical receiver that receives the output optical signal and converts it to the downlink radio signal, and the optical modulator that performs optical modulation on the other output optical signal of the optical splitter by the uplink radio signal And an electro-absorption optical modulator that simultaneously performs light modulation and upstream optical signal modulation.

  According to the seventh aspect of the present invention, the optical base station receives the optical signal transmitted from the optical transmitter and converts it into a downlink radio signal (optical detection operation), and the optical signal transmitted from the optical transmitter Since the operation of performing optical intensity modulation on the received uplink radio signal (optical modulation operation) can be performed by a single electroabsorption optical modulator, the configuration of the radio base station can be simplified.

(Eighth invention)
An eighth invention is the optical-wireless fusion communication system according to any one of the first to seventh inventions, wherein the optical transmitter, the radio base station, and the optical receiver are connected via a single-core optical transmission line. The accommodation station and the radio base station are provided with a bidirectional optical separator that separates the upstream optical signal and the downstream optical signal.

  According to the eighth invention, optical transmission of the downlink radio signal from the optical transmitter to the radio base station and optical transmission of the uplink radio signal from the radio base station to the optical receiver are performed on a single-core optical transmission path. Can do.

  Usually, when bidirectional optical transmission is performed on a single optical transmission line in this way, a part of the optical signal transmitted from the optical transmitter is reflected in the optical transmission line, and this reflected light is combined with the upstream optical signal. There is a concern that the reception characteristic may be deteriorated by inputting to the optical receiver.

  However, in the optical receiver of the present invention, the uplink modulated optical signal (formulas (4) and (11)) transmitted from the radio base station is an optical local signal (from the optical signal generator in the accommodating station) ( It is converted into an intermediate frequency band signal by optical heterodyne detection with (2) and (9)), but the reflected light of the optical signal transmitted from the optical transmitter to the radio base station (equation (1), (8) And the beat signal obtained by optical heterodyne detection of the optical local signal (equation (2), equation (9)) does not enter the above intermediate frequency band, and is transmitted from the optical transmitter to the radio base station. The optical signal is not affected by reflection in the optical transmission line.

(9th invention)
According to a ninth aspect of the present invention, an optical signal generator, an optical transmitter, and an optical receiver are provided in a receiving station, and the optical transmitter is a downstream optical wireless signal modulated by downstream transmission data to a wireless base station via an optical transmission line. And the uplink optical carrier signal, the radio base station transmits the downlink radio signal (frequency f _RF-d ) obtained by receiving the downlink optical radio signal to the radio terminal, and the uplink transmission data The radio signal modulated with the radio frequency (frequency f _RF-u ) is received, the optical carrier signal for the uplink is optically modulated with the received uplink radio signal, and the modulated optical signal is transmitted to the accommodation station via the optical transmission line. The optical receiver is characterized by the optical signal generator, the optical transmitter, and the optical receiver in the optical-wireless combined communication method for receiving the modulated optical signal, detecting it, and reproducing the upstream transmission data.

The optical signal generator splits the first single spectrum optical signal (center frequency f _c1 ) into two, and half of the frequency f _RF-d of the desired downlink radio signal (one half of the output optical signal) The optical carrier-suppressed double-sideband modulation is performed with the electric carrier signal of f _RF-d / 2), the carrier-suppressed double-sideband modulated optical signal is input to the optical transmitter, and the other branched output optical signal Are input to the optical transmitter as an optical carrier signal for uplink, and the polarization directions of the second single spectrum optical signal (center frequency f _c2 ) and the third single spectrum optical signal (center frequency f _c3 ) So that the two waves are orthogonally polarized and combined to output an optical receiver, and the first, second and third single-spectrum optical signals are output. Center frequencies f _c1 , f _c2 , and f _c3 are the frequencies f _RF-u of the uplink radio signal, For frequency f _IF1 and f _IF2
| F _c1 −f _c2 | = f _RF−u ± f _{IF1
| F c1 -f c3 | = f} RF-u ± f IF2
Control to be

  The optical transmitter performs optical modulation on the carrier-suppressed double-sideband modulated optical signal of the two input optical signals with downlink transmission data, and uses the output optical signal as a downlink optical radio signal, thereby generating an optical carrier for uplink After combining with the signal, it is transmitted to the radio base station.

The optical receiver combines the modulated optical signal transmitted from the radio base station and the polarization combined optical signal output from the optical signal generator, and receives the combined optical signal to obtain an intermediate signal The electrical signals of the frequencies f _IF1 and f _IF2 are detected, and the output signal is low-pass filtered to generate upstream transmission data.

(Tenth invention)
According to a tenth aspect of the present invention, an optical signal generator, an optical transmitter, and an optical receiver are provided in a receiving station, and the optical transmitter is a downstream optical wireless signal that is modulated with downstream transmission data by a wireless base station via an optical transmission line. And the uplink optical carrier signal, the radio base station transmits the downlink radio signal (frequency f _RF-d ) obtained by receiving the downlink optical radio signal to the radio terminal, and the uplink transmission data The radio signal modulated with the radio frequency (frequency f _RF-u ) is received, the optical carrier signal for the uplink is optically modulated with the received uplink radio signal, and the modulated optical signal is transmitted to the accommodation station via the optical transmission line. The optical receiver is characterized by the optical signal generator, the optical transmitter, and the optical receiver in the optical-wireless combined communication method for receiving the modulated optical signal, detecting it, and reproducing the upstream transmission data.

The optical signal generator splits the first single spectrum optical signal (center frequency f _c1 ) into two, and half of the frequency f _RF-d of the desired downlink radio signal (one half of the output optical signal) The optical carrier-suppressed double-sideband modulation is performed with the electric carrier signal of f _RF-d / 2), the carrier-suppressed double-sideband modulated optical signal is input to the optical transmitter, and the other branched output optical signal Are output to the optical receiver, and the polarization directions of the second single spectrum optical signal (center frequency f _c2 ) and the third single spectrum optical signal (center frequency f _c3 ) are orthogonal and equal. A polarization-combined optical signal obtained by combining two waves with orthogonal polarization so as to obtain optical intensity is input to an optical transmitter as an optical carrier signal for uplink, and first, second, and third single-spectrum optical signals Center frequencies f _c1 , f _c2 , and f _c3 are the frequencies f _RF-u of the uplink radio signal, For frequency f _IF1 and f _IF2
| F _c1 −f _c2 | = f _RF−u ± f _{IF1
| F c1 -f c3 | = f} RF-u ± f IF2
Control to be

  The optical transmitter performs optical modulation on the carrier-suppressed double-sideband modulated optical signal of the two input optical signals with downlink transmission data, and uses the output optical signal as a downlink optical radio signal, thereby generating an optical carrier for uplink After combining with the signal, it is transmitted to the radio base station.

The optical receiver is obtained by combining the modulated optical signal transmitted from the radio base station and the single-spectrum optical signal output from the optical signal generator, and receiving the combined optical signal. The electrical signals of the intermediate frequencies f _IF1 and f _IF2 are detected, and the output signal is low-pass filtered to generate upstream transmission data.

(Eleventh invention)
In an eleventh aspect based on the ninth or tenth aspect, the optical receiver separates the electrical signals of the intermediate frequencies f _IF1 and f _IF2 and separates the electrical signal of the intermediate frequency f _{IF1 and} the electrical signal of the intermediate frequency f _IF2 respectively. Detection is performed, and each output signal is added to generate upstream transmission data.

(Twelfth invention)
A twelfth aspect of the present invention is, respectively, in the ninth invention or the tenth, the optical receiver separates the electrical signal having the intermediate frequency f _IF1, f _IF2, an electrical signal of the electrical signal and the intermediate frequency f _IF2 intermediate frequency f _IF1 Detection is performed, and the phases of the output signals are aligned and then added to generate upstream transmission data.

  As described above, the optical-radio fusion communication system of the present invention shares an optical signal generation unit in uplink / downlink, and does not use an optical modulator in a radio frequency band for an optical transmitter. A stable intermediate frequency modulation signal can be obtained with a single light receiver without using an intermediate frequency stabilization circuit and a polarization fluctuation compensation circuit in the receiver. As a result, the optical-wireless fusion communication system can realize bidirectional optical transmission with an inexpensive and simple configuration and can receive the modulated optical signal transmitted from the wireless base station with high sensitivity. Expansion and system cost reduction are possible.

(First embodiment)
FIG. 1 shows a first embodiment of an optical-radio fusion communication system of the present invention. In the present embodiment, a description will be given based on a configuration example in which one radio base station 300 is connected to the accommodating station 100 and one radio terminal 400 is connected to the radio base station.

  In FIG. 1, the accommodation station 100 includes an optical signal generator 101, an optical transmitter 109, and an optical receiver 112.

The optical signal generator 101 includes single spectrum light sources 102, 103, and 104 that output single spectrum optical signals ( _fc1 , _fc2 , _fc3 ) 1a, 1b, and 1c, respectively, and a single spectrum optical signal 1a. And an optical modulator for subjecting one output optical signal of the optical splitter 105 to optical carrier-suppressed double-sideband modulation with an output electrical signal (frequency f _RF-d / 2) from the electrical oscillator 106 107, a single-spectrum optical signal 1b, 1c, and a polarization combining unit that outputs a polarization-combined optical signal 1e obtained by orthogonally combining the polarization directions so that their polarization directions are orthogonal and equal to each other. 108.

  The output optical signal 1d of the optical modulator 107 and the other output optical signal 1a of the optical splitter 105 are input to the optical transmitter 109, and the polarization combined optical signal 1e is input to the optical receiver 112.

  The optical transmitter 109 includes an optical modulator 110 that modulates the carrier-suppressed double-sideband modulated optical signal 1d input from the optical signal generator 101 with downlink transmission data, and a single spectrum input from the optical signal generator 101. An optical multiplexer 111 that multiplexes the optical signal 1a and the output optical signal of the optical modulator 110 as an uplink optical carrier signal and a downstream optical wireless signal is provided. The output combined optical signal 1 f of the optical multiplexer 111 is transmitted to the radio base station 300 via the optical transmission path 201.

The radio base station 300 includes an optical branching unit 301 that branches the optical signal 1f transmitted from the optical transmitter. One output optical signal of the optical branching device 301 is received by the light receiving device 302 to be converted into a downlink wireless signal (frequency f _RF-d ) 1 g and transmitted from the antenna 303 to the wireless terminal 400. The other output optical signal of the optical splitter 301 is optical intensity modulated by the upstream radio signal (frequency f _RF-u ) 1h transmitted from the wireless terminal 400 by the optical modulator 304, and the modulated optical signal 1i is optically transmitted. The signal is transmitted to the optical receiver 112 of the accommodation station 100 via the path 202.

  The optical receiver 112 includes the modulated optical signal 1 i transmitted from the optical modulator 304 of the radio base station 300 and the polarization combined optical signal output from the polarization combining unit 108 of the optical signal generator 101 in the accommodating station 100. 1e is input, and the uplink transmission data 1m transmitted from the radio terminal 400 via the radio base station 300 is reproduced.

  FIG. 2 shows a configuration example of the polarization beam combining means 108. In FIG. 2, single spectrum optical signals 1b and 1c are adjusted by the polarization adjusters 108-1 and 108-2 so that their polarization directions are orthogonal to each other, and output adjusters 118-3 and 118-4. Are adjusted so that their optical intensities are equal to each other, and are orthogonally polarized by the polarization-maintaining optical multiplexer 108-5 and output as a polarization-combined optical signal 1e. This configuration is an example. For example, the single spectrum light sources 103 and 104 have the functions of the polarization adjusters 108-1 and 108-2 and the output adjusters 108-3 and 108-4. The reference numeral 108 may be constituted only by the polarization maintaining type optical multiplexer 108-5.

  FIG. 3 shows a first configuration example of the optical receiver 112. FIG. 6 shows an example of the frequency spectrum of each signal in the first embodiment and the first configuration example of the optical receiver 112.

  In FIG. 3, the optical receiver 112-1 includes an optical multiplexer 113, a light receiver 114, an electric detector 115, and a low-pass filter 116. The optical multiplexer 113 combines the modulated optical signal 1i transmitted from the radio base station and the polarization combined optical signal 1e output from the optical signal generator 101, and the combined optical signal 1j is received by the optical receiver 114. Is converted into an electrical signal.

Here, in the optical signal generation unit 101, the center frequencies f _c1 , f _c2 , and f _c3 of the single-spectrum optical signals 1a, 1b, and 1c are the frequencies f _RF-u and the predetermined intermediate frequency f of the upstream radio signal 1h. _{For IF1} and _fIF2 ,
| F _c1 −f _c2 | = f _RF−u ± f _{IF1
| F c1 -f c3 | = f} RF-u ± f IF2
It is controlled to become.

As a result, the electric signal 1k having two stable intermediate frequencies f _IF1 and f _IF2 can be directly output as the output of the light receiver 114 without using the millimeter wave band component or the intermediate frequency stabilization circuit in the optical receiver 112-1. Obtainable. Furthermore, a gain by optical heterodyne detection can be obtained by inputting the polarization-combined optical signal 1e with sufficient light intensity from the optical signal generator 101 to the optical receiver 112-1. The electrical signal 1k output from the light receiver 114 is collectively detected by the electrical detector 115, and the upstream transmission data 1m can be obtained by passing the detection signal 1l through the low-pass filter 116.

  Here, since the polarization-combined optical signal 1e output from the optical signal generator 101 has the polarization directions orthogonal to each other and the same light intensity, the upstream data signal 1m output from the low-pass filter 116 Is a constant value without depending on the polarization direction of the modulated optical signal 1 i transmitted from the radio base station 300.

  FIG. 4 shows a second configuration example of the optical receiver 112. FIG. 7 shows an example of the frequency spectrum of each signal in the first embodiment and the second configuration example of the optical receiver 112.

In FIG. 4, the optical receiver 112-2 includes an optical multiplexer 113, a light receiver 114, a filter 117, electric detectors 115-1 and 115-2, and an electric adder 118. The optical multiplexer 113 combines the modulated optical signal 1i transmitted from the radio base station and the polarization combined optical signal 1e output from the optical signal generator 101, and the combined optical signal 1j is received by the optical receiver 114. Is converted into an electrical signal. Then, according to the above frequency relationship, it is possible to obtain a stable electric signal 1k having two intermediate frequencies f _IF1 and f _IF2 directly as an output of the light receiver 114.

Filter 117 inputs the electric signal 1k intermediate frequency f _IF1, f _IF2, separates into an electric signal 1k ₂ electrical signals 1k ₁ and the intermediate frequency f _IF2 intermediate frequency f _IF1. The electrical signals 1k ₁ and 1k ₂ are detected by the electrical detectors 115-1 and 115-2, respectively, and the upstream transmission data 1m can be obtained by adding the respective detected signals by the electrical adder 118.

  Here, since the polarization combined optical signal 1e output from the optical signal generation unit 101 has orthogonal polarization directions and equal optical intensities, the upstream data signal 1m output from the electrical adder 118 is It becomes a constant value without depending on the polarization direction of the modulated optical signal 1 i transmitted from the radio base station 300.

  FIG. 5 shows a third configuration example of the optical receiver 112. 7 and 8 show an example of the frequency spectrum and time chart of each signal in the first embodiment and the third configuration example of the optical receiver 112. FIG.

5, the optical receiver 112-3 includes an optical multiplexer 113, a light receiver 114, a filter 117, electric detectors 115-1 and 115-2, and a phase adjustment electric adder 119. Optical multiplexer 113, the photodetector 114, a filter 117, is output electrical signal 1k ₂ electrical signals 1k ₁ and the intermediate frequency f _IF2 intermediate frequency f _IF1 is, are detected respectively by electric detectors 115-1 and 115-2 The configuration is the same as that of the optical receiver 112-2.

In this configuration, as shown in FIG. 8, by the dispersion of the optical transmission line 201, the output signal 1l ₂ between the output signal 1l ₁ of the first electrical detector 115-1 second electrical detector 115-2 It is assumed that there is a time difference ΔT. At this time, the phase adjustment electrical adder 119 adds the output signals 1l ₁ and 1l _{2 with} the same phase, thereby compensating for the time difference and obtaining the upstream transmission data 1m that is not affected by the dispersion of the optical transmission line.

(Second Embodiment)
FIG. 9 shows a second embodiment of the optical-radio fusion communication system of the present invention. In the present embodiment, a description will be given based on a configuration example in which one radio base station 300 is connected to the accommodating station 100 and one radio terminal 400 is connected to the radio base station.

  In FIG. 9, the accommodating station 100 includes an optical signal generation unit 101, an optical transmitter 109, and an optical receiver 112.

The optical signal generator 101 includes single spectrum light sources 102, 103, and 104 that output single spectrum optical signals ( _fc1 , _fc2 , _fc3 ) 2a, 2b, and 2c, respectively, and a single spectrum optical signal 2a. And an optical modulator for subjecting one output optical signal of the optical splitter 105 to optical carrier-suppressed double-sideband modulation with an output electrical signal (frequency f _RF-d / 2) from the electrical oscillator 106 107 and a single-spectrum optical signal 2b, 2c, and a polarization combining means for outputting a polarization-combined optical signal 2e obtained by orthogonally-polarizing the signals so that their polarization directions are orthogonal to each other and equal light intensity. 108.

  The output optical signal 2 d of the optical modulator 107 and the polarization combined optical signal 2 e are input to the optical transmitter 109, and the other output optical signal 2 a of the optical splitter 105 is input to the optical receiver 112.

  The optical transmitter 109 includes an optical modulator 110 that modulates the carrier-suppressed double-sideband modulated optical signal 2 d input from the optical signal generator 101 with downlink transmission data, and a polarization-combined light input from the optical signal generator 101. An optical multiplexer 111 that multiplexes the signal 2e and the output optical signal of the optical modulator 110 as an uplink optical carrier signal and a downstream optical wireless signal, respectively. The output combined optical signal 2 f of the optical multiplexer 111 is transmitted to the radio base station 300 via the optical transmission path 201.

The radio base station 300 includes an optical branching unit 301 that branches the optical signal 2f transmitted from the optical transmitter. One output optical signal of the optical branching device 301 is received by the light receiving device 302 to be converted into a downlink wireless signal (frequency f _RF-d ) 2 g and transmitted from the antenna 303 to the wireless terminal 400. The other output optical signal of the optical splitter 301 is optical intensity modulated by the upstream radio signal (frequency f _RF-u ) 2h transmitted from the wireless terminal 400 by the optical modulator 304, and the modulated optical signal 2i is optically transmitted. The signal is transmitted to the optical receiver 112 of the accommodation station 100 via the path 202.

  The optical receiver 112 receives the modulated optical signal 2i transmitted from the optical modulator 304 of the radio base station 300 and the single spectrum optical signal 2a output from the optical signal generator 101 in the accommodating station 100, In this configuration, uplink transmission data 2m transmitted from the wireless terminal 400 via the wireless base station 300 is reproduced.

  FIG. 10 shows a configuration example of the polarization beam combining means 108. In FIG. 2, optical signals 2b and 2c having a single spectrum are adjusted by the polarization adjusters 108-1 and 108-2 so that their polarization directions are orthogonal to each other, and output adjusters 118-3 and 118-4. Are adjusted so that their optical intensities are equal to each other, and are orthogonally polarized by the polarization maintaining optical multiplexer 108-5, and output as a polarization combined optical signal 2e. This configuration is an example. For example, the single spectrum light sources 103 and 104 have the functions of the polarization adjusters 108-1 and 108-2 and the output adjusters 108-3 and 108-4. The reference numeral 108 may be constituted only by the polarization maintaining type optical multiplexer 108-5.

  FIG. 11 shows a first configuration example of the optical receiver 112. FIG. 14 shows an example of the frequency spectrum of each signal in the second embodiment and the first configuration example of the optical receiver 112.

  In FIG. 11, the optical receiver 112-1 includes an optical multiplexer 113, a light receiver 114, an electric detector 115, and a low-pass filter 116. The optical multiplexer 113 combines the modulated optical signal 2i transmitted from the radio base station and the single spectrum optical signal 2a output from the optical signal generator 101, and the combined optical signal 2j is received by the optical receiver. In 114, it is converted into an electrical signal.

Here, in the optical signal generation unit 101, the center frequencies f _c1 , f _c2 , and f _c3 of the single-spectrum optical signals 2a, 2b, and 2c are the same as the frequency f _RF-u of the uplink radio signal 2h and the predetermined intermediate frequency f. _{For IF1} and _fIF2 ,
| F _c1 −f _c2 | = f _RF−u ± f _{IF1
| F c1 -f c3 | = f} RF-u ± f IF2
It is controlled to become.

As a result, the electrical signal 2k of the stable two-wave intermediate frequencies f _IF1 and f _IF2 can be directly output as the output of the light receiver 114 without using the millimeter wave band components and the intermediate frequency stabilization circuit in the optical receiver 112-1. Obtainable. Furthermore, a gain by optical heterodyne detection is obtained by inputting a single spectrum optical signal 2a having sufficient light intensity from the optical signal generator 101 to the optical receiver 112-1. The electrical signal 2k output from the light receiver 114 is collectively detected by the electrical detector 115, and the upstream transmission data 2m can be obtained by passing the detection signal 21 through the low-pass filter 116.

  Here, since the polarization-combined optical signal 2e output from the optical signal generation unit 101 to the optical transmitter has a polarization direction orthogonal to each other and equal optical intensity, it is output from the low-pass filter 116. The uplink data signal 2m has a constant value without depending on the polarization direction of the modulated optical signal 2i transmitted from the radio base station 300.

  FIG. 12 shows a second configuration example of the optical receiver 112. FIG. 15 shows an example of the frequency spectrum of each signal in the second embodiment and the second configuration example of the optical receiver 112.

In FIG. 12, the optical receiver 112-2 includes an optical multiplexer 113, a light receiver 114, a filter 117, electric detectors 115-1 and 115-2, and an electric adder 118. The optical multiplexer 113 combines the modulated optical signal 2i transmitted from the radio base station and the single spectrum optical signal 2a output from the optical signal generator 101, and the combined optical signal 2j is received by the optical receiver. In 114, it is converted into an electrical signal. Then, according to the above frequency relationship, it is possible to directly obtain the stable electric signal 2k having two intermediate frequencies f _IF1 and f _IF2 as the output of the light receiver 114.

Filter 117 receives the electrical signal 2k of the intermediate frequency f _IF1, f _IF2, it separates the electrical signal 2k ₂ electrical signals 2k ₁ and the intermediate frequency f _IF2 intermediate frequency f _IF1. The electric signals 2k ₁ and 2k ₂ are detected by the electric detectors 115-1 and 115-2, respectively, and the detected signals are added by the electric adder 118, whereby the upstream transmission data 2m can be obtained.

  Here, since the polarization-combined optical signal 2e output from the optical signal generation unit 101 to the optical transmitter has orthogonal polarization directions and equal optical intensities, the uplink output from the electric adder 118 The data signal 2m is a constant value without depending on the polarization direction of the modulated optical signal 2i transmitted from the radio base station 300.

  FIG. 13 shows a third configuration example of the optical receiver 112. FIGS. 15 and 16 show an example of the frequency spectrum of each signal and a time chart in the second embodiment and the third configuration example of the optical receiver 112.

In FIG. 13, an optical receiver 112-3 includes an optical multiplexer 113, a light receiver 114, a filter 117, electric detectors 115-1 and 115-2, and a phase adjustment electric adder 119. Optical multiplexer 113, the photodetector 114, a filter 117, is output electrical signal 2k ₂ electrical signals 2k ₁ and the intermediate frequency f _IF2 intermediate frequency f _IF1 is, are detected respectively by electric detectors 115-1 and 115-2 The configuration is the same as that of the optical receiver 112-2.

In this configuration, as shown in FIG. 16, the dispersion of the optical transmission line 201, the output signal of the output signal 2l ₁ of the first electrical detector 115-1 second electrical detector 115-2 2l ₂ It is assumed that there is a time difference ΔT. At this time, the phase adjustment electric adder 119 adds the phases of the output signals 2l ₁ and 2l ₂ in alignment, thereby compensating for the time difference and obtaining the upstream transmission data 2m that is not affected by the dispersion of the optical transmission line.

(Third embodiment)
FIG. 17 shows a third embodiment of the optical-radio fusion communication system of the present invention. In the present embodiment, based on a configuration in which a plurality of radio base stations 300-A to 300-C are connected to the accommodating station 100, and a radio terminal (not shown) is connected to each radio base station 300. explain.

17, the accommodation station 100 includes an optical signal generation unit 101, a plurality of optical transmitters 109-A to 109-C, and a plurality of optical receivers 112-A to 112-C. The optical signal generator 101 includes single spectrum light sources 102, 103, and 104 that output single spectrum optical signals ( _fc1 , _fc2 , _fc3 ) 1a, 1b, and 1c, respectively, and a single spectrum optical signal 1a. , An optical branching device 120 for branching the output optical signal (1a) of the optical branching device 105 into a plurality, and another output optical signal of the optical branching device 105 from the electric oscillator 106 An optical modulator 107 that performs optical carrier-suppressed double-sideband modulation with a signal (frequency f _RF-d / 2), an optical splitter 121 that branches the output optical signal 1d of the optical modulator 107 into a plurality, and a single spectrum Polarization combining means 108 for inputting the optical signals 1b and 1c, outputting the polarization combined optical signal 1e obtained by combining the orthogonal polarizations so that the polarization directions thereof are orthogonal and equal in intensity, and polarization combined light Light that branches signal 1e into multiple Comprising a 岐器 122.

  The optical signal 1a having a single spectrum branched into a plurality and the output optical signal 1d of the optical modulator 107 branched into a plurality are input to a plurality of optical transmitters 109-A to 109-C and branched into a plurality. The polarization combined optical signal 1e is input to the plurality of optical receivers 112-A to 112-C.

  In the optical transmitters 109 -A to 109 -C, the carrier-suppressed double-sideband modulated optical signal 1 d input from the optical signal generator 101 is optically modulated with downlink transmission data, and the single signal input from the optical signal generator 101 is input. Optical signals 1f-A to 1f-C obtained by combining with optical signal 1a in the spectrum are transmitted to radio base stations 300-A to 300-C via optical transmission lines 201-A to 201-C. .

The radio base stations 300-A to 300-C branch the optical signals 1f-A to 1f-C transmitted from the optical transmitter, and receive one of the output optical signals to receive a downlink radio signal (frequency f _{RF− d} ) Convert to 1 g and send from antenna 303 to wireless terminal. The other output optical signal of the optical branching unit is optical intensity modulated by the upstream radio signal (frequency f _RF-u ) 1h transmitted from the radio terminal, and the obtained modulated optical signals 1i-A to 1i-C are optical signals. The signals are transmitted to the optical receivers 112-A to 112-C of the accommodation station 100 via the transmission paths 202-A to 202-C.

  The optical receivers 112-A to 112-C are the modulated optical signals 1i-A to 1i-C transmitted from the radio base stations 300-A to 300-C and the light of the optical signal generator 101 in the accommodation station 100. Each of the polarization-coupled optical signals 1e branched by the branching device 122 is input, and the upstream transmission data 1m-A to 1m-C are reproduced.

  The present embodiment is characterized in that, in the first embodiment shown in FIG. 1, the optical branching device 120 that branches the optical signal 1a to the optical signal generator 101, the optical branching device 121 that branches the optical signal 1d, and the polarization An optical branching device 122 that branches the combined optical signal 1e is provided, and a plurality of radio base stations 300-A to 300-C, a plurality of optical transmitters 109-A to 109-C, and a plurality of optical receivers 120-A to 120 are provided. It has been expanded to the -C relationship. The relationship between a set of radio base stations 300, the optical transmitter 109, and the optical receiver 112, particularly the configuration of the optical receiver 112 and the function of reproducing the uplink transmission data 1m from the modulated optical signal 1i transmitted from the radio base station 300 Is the same as in the case of the first embodiment.

(Fourth embodiment)
FIG. 18 shows a fourth embodiment of the optical-radio fusion communication system of the present invention. In the present embodiment, based on a configuration in which a plurality of radio base stations 300-A to 300-C are connected to the accommodating station 100, and a radio terminal (not shown) is connected to each radio base station 300. explain.

18, the accommodation station 100 includes an optical signal generation unit 101, a plurality of optical transmitters 109-A to 109-C, and a plurality of optical receivers 112-A to 112-C. The optical signal generator 101 includes single spectrum light sources 102, 103, and 104 that output single spectrum optical signals ( _fc1 , _fc2 , _fc3 ) 2a, 2b, and 2c, respectively, and a single spectrum optical signal 2a. The optical branching device 105 for branching the optical branching device, the optical branching device 120 for branching the output optical signal (2a) of the optical branching device 105 into a plurality, and the other output optical signal of the optical branching device 105 from the electric oscillator 106 An optical modulator 107 that performs optical carrier suppression double-sideband modulation with a signal (frequency f _RF-d / 2), an optical splitter 121 that splits the output optical signal 2d of the optical modulator 107 into a plurality, and a single spectrum Polarization combining means 108 for inputting the optical signals 2b and 2c, outputting the polarization combined optical signal 2e obtained by combining the orthogonal polarizations so that the polarization directions thereof are orthogonal and equal in intensity, and polarization combined light Light that branches signal 2e into multiple Comprising a 岐器 122.

  The output optical signal 2d of the optical modulator 107 branched into a plurality and the polarization combined optical signal 2e branched into a plurality are input to the plurality of optical transmitters 109-A to 109-C, The optical signal 2a having one spectrum is input to a plurality of optical receivers 112-A to 112-C.

  In the optical transmitters 109 -A to 109 -C, the carrier-suppressed double-sideband modulated optical signal 2 d input from the optical signal generation unit 101 is optically modulated with downlink transmission data, and the polarization input from the optical signal generation unit 101 Optical signals 2f-A to 2f-C obtained by combining with the combined optical signal 2e are transmitted to the radio base stations 300-A to 300-C via the optical transmission lines 201-A to 201-C.

The radio base stations 300-A to 300-C branch the optical signals 2f-A to 2f-C transmitted from the optical transmitter and receive one of the output optical signals to receive a downlink radio signal (frequency f _{RF− d} ) Convert to 2g, and send from antenna 303 to wireless terminal. The other output optical signal of the optical branching unit is optical intensity modulated by the uplink radio signal (frequency f _RF-u ) 2h transmitted from the wireless terminal, and the obtained modulated optical signals 2i-A to 2i-C are optical signals. The signals are transmitted to the optical receivers 112-A to 112-C of the accommodation station 100 via the transmission paths 202-A to 202-C.

  The optical receivers 112-A to 112-C are optical signals from the modulated optical signals 2i-A to 2i-C transmitted from the radio base stations 300-A to 300-C and the optical signal generator 101 in the accommodating station 100. Each of the single-spectrum optical signals 2a branched by the branching device 120 is input, and uplink transmission data 2m-A to 2m-C are reproduced.

  The feature of this embodiment is that in the second embodiment shown in FIG. 9, the optical branching device 120 for branching the optical signal 2a to the optical signal generator 101, the optical branching device 121 for branching the optical signal 2d, and the polarization An optical branching device 122 that branches the combined optical signal 2e is provided, and a plurality of radio base stations 300-A to 300-C, a plurality of optical transmitters 109-A to 109-C, and a plurality of optical receivers 120-A to 120 are provided. It has been expanded to the -C relationship. Relationship between one set of radio base station 300, optical transmitter 109, and optical receiver 112, particularly the configuration of optical receiver 112 and the function of reproducing uplink transmission data 2m from modulated optical signal 2i transmitted from radio base station 300 Is the same as in the case of the second embodiment.

(Fifth embodiment)
FIG. 19 shows the configuration of a radio base station 300 according to the fifth embodiment of the optical-radio fusion communication system of the present invention.

  The feature of this embodiment is that in the first to fourth embodiments, an optical branching device 301 for branching the optical signals 1f and 2f transmitted from the optical transmitter 109 to the radio base station 300, and this optical branching device A light receiving unit 302 that receives one output optical signal 301 and converts it into downlink radio signals 1g and 2g, and an optical modulation that modulates the other output optical signal of the optical splitter 301 with the upstream radio signals 1h and 2h. Instead of the unit 304, an electroabsorption optical modulator 306 is provided. With this single electroabsorption optical modulator 306, the generation of the downlink radio signals 1g and 2g by receiving the optical signals 1f and 2f, and the uplink radio signal The optical modulation by 1h and 2h is performed simultaneously. Between the electroabsorption optical modulator 306 and the transmitting antenna 303 and the receiving antenna 305, a bidirectional radio signal separator 307 using a radio frequency band circulator, a directional coupler or the like is connected, and the electroabsorption optical modulation is performed. Downlink radio signals 1g and 2g output from the antenna 306 to the antenna 303 and uplink radio signals 1h and 2h input from the antenna 305 to the electroabsorption optical modulator 306 are separated.

  The relationship between the radio base station 300, the optical transmitter 109 and the optical receiver 112, the configuration of the optical receiver 112, and the modulated optical signals 1i and 2i transmitted from the radio base station 300 are used to obtain upstream transmission data 1m and 2m. The function to reproduce is the same as in the first to fourth embodiments.

(Sixth embodiment)
FIG. 20 shows a sixth embodiment of the optical-radio fusion communication system of the present invention.

  The feature of the present embodiment is that, in the first embodiment, the optical branching unit in the radio base station 300 is transmitted from the optical transmitter 109 to the accommodating station 100 and the radio base station 300, and is transmitted through the optical transmission path 203. And the optical signal 1 i output from the optical modulator 304 in the radio base station 300 and input to the optical receiver 112 in the accommodating station 100 via the optical transmission path 203 are separated. Bi-directional optical separators 123 and 308 are provided for optical transmission of the downlink radio signal 1g from the optical transmitter 109 to the radio base station 300 and optical transmission of the downlink radio signal 1h from the radio base station 300 to the optical receiver 112. Bidirectional optical transmission is performed on a single-core optical transmission path 203. An example of an optical component that realizes this bidirectional optical separator is an optical circulator.

  Similarly, in the second to fifth embodiments, light transmitted from the optical transmitter 109 to the radio base station 300 using the bidirectional optical separators 123 and 308 in the accommodating station 100 and the radio base station 300 is used. By separating the signals 1f and 2f and the optical signals 1i and 2i transmitted from the radio base station 300 to the optical receiver 112, bidirectional optical transmission can be realized on the one-core optical transmission path 203.

The figure which shows 1st Embodiment of the optical-radio fusion communication system of this invention. The figure which shows the structural example of the polarization | polarized-light synthesis means in 1st Embodiment. The figure which shows the 1st structural example of the optical receiver in 1st Embodiment. The figure which shows the 2nd structural example of the optical receiver in 1st Embodiment. The figure which shows the 3rd structural example of the optical receiver in 1st Embodiment. The figure which shows an example of the frequency spectrum of each signal in 1st Embodiment and the 1st structural example of an optical receiver. The figure which shows an example of the frequency spectrum of each signal in the 2nd, 3rd structural example of 1st Embodiment and an optical receiver. Time chart of each signal in the first embodiment and the third configuration example of the optical receiver The figure which shows 2nd Embodiment of the optical-radio fusion communication system of this invention. The figure which shows the structural example of the polarization | polarized-light synthesis means in 2nd Embodiment. The figure which shows the 1st structural example of the optical receiver in 2nd Embodiment. The figure which shows the 2nd structural example of the optical receiver in 2nd Embodiment. The figure which shows the 3rd structural example of the optical receiver in 2nd Embodiment. The figure which shows an example of the frequency spectrum of each signal in 2nd Embodiment and the 1st structural example of an optical receiver. The figure which shows an example of the frequency spectrum of each signal in 2nd Embodiment and the 2nd, 3rd structural example of an optical receiver. Time chart of each signal in the second embodiment and the third configuration example of the optical receiver The figure which shows 3rd Embodiment of the optical-radio fusion communication system of this invention. The figure which shows 4th Embodiment of the optical-radio fusion communication system of this invention. The figure which shows the wireless base station of 5th Embodiment of the optical-radio fusion communication system of this invention. The figure which shows 6th Embodiment of the optical-radio fusion communication system of this invention. Configuration diagram showing an example of a conventional optical-wireless fusion communication system The figure which shows an example of the frequency spectrum of each signal in the conventional optical-radio fusion communication system

Explanation of symbols

  100: accommodation station, 101: optical signal generator, 102, 103, 104: single spectrum light source, 105, 120, 121, 122: optical splitter, 106: electric oscillator, 107, 110: optical modulator, 108: Polarization combining means, 108-1, 108-2: Polarization regulator, 108-3, 108-4: Output regulator, 109, 109-A, 109-B, 109-C: Optical transmitter, 111, 113, 108-5: optical multiplexer, 112, 112-1, 112-2, 112-3, 112-A, 112-B, 112-C: optical receiver, 114: light receiver, 115, 115-1 , 115-2: Electric detector, 116: Low-pass filter, 117: Filter, 118: Electric adder, 119: Phase adjustment electric adder, 123: Bidirectional separator, 201, 201-A, 201-B , 201-C, 2 2, 202-A, 202-B, 202-C: optical transmission line, 300, 300-A, 300-B, 300-C: wireless base station, 301: optical splitter, 302: light receiver, 303, 305 : Antenna, 304: Optical modulator, 306: Electroabsorption optical modulator, 307: Bidirectional wireless signal separator, 308: Bidirectional separator, 400: Wireless terminal, 401: Electric oscillator, 402: Electric modulator, 403, 405: Antenna, 404: Electric demodulator.

Claims (12)

The accommodation station is equipped with an optical signal generator, an optical transmitter and an optical receiver,
The optical transmitter transmits a downlink optical radio signal modulated with downlink transmission data and an optical carrier signal for uplink via an optical transmission path to a radio base station,
The radio base station bifurcates the received optical signal with an optical splitter, and receives a downlink radio signal (frequency f _RF-d ) obtained by receiving one output optical signal of the optical splitter to the wireless terminal. Transmitting, receiving a radio signal (frequency f _RF-u ) modulated with uplink transmission data, optically modulating the other output optical signal of the optical splitter with the received uplink radio signal, and modulating the optical signal To the accommodation station via an optical transmission line,
The optical receiver receives the modulated optical signal, detects and recovers the upstream transmission data in an optical-radio fusion communication system,
The optical signal generator is
A first single-spectrum light source that outputs a first single-spectrum optical signal (center frequency f _c1 );
A second single spectrum light source for outputting a second single spectrum optical signal (center frequency f _c2 );
A third single spectrum light source that outputs a third single spectrum optical signal (center frequency f _c3 );
An optical branching device that branches the optical signal of the first single spectrum in two, and a half value (f _RF− of the frequency f _RF-d of a desired downlink radio signal with respect to one output optical signal of the optical branching device. _an optical modulator for performing optical carrier suppressed double-sideband modulation with an electric carrier signal of _d / 2),
The polarization direction and light intensity of the second single-spectrum optical signal and the polarization direction and light intensity of the third single-spectrum optical signal are orthogonal and equal to each other. Polarization adjustment means for adjusting the light intensity and orthogonally combining the two waves and outputting them as a polarization combined optical signal;
The center frequencies f _c1 , f _c2 , and f _c3 of the first, second, and third single spectrum optical signals are set to the frequency f _RF-u and the predetermined intermediate frequencies f _IF1 and f _IF2 of the uplink radio signal, respectively. for,
| F _c1 −f _c2 | = f _RF−u ± f _{IF1
| F c1 -f c3 | = f} RF-u ± f IF2
Controlled to be
The carrier-suppressed double-sideband modulated optical signal is input to an optical transmitter, and the other output optical signal of the optical splitter is input to the optical transmitter as the uplink optical carrier signal, and the polarization combining It is configured to output an optical signal to the optical receiver,
The optical transmitter includes an optical modulator that optically modulates the carrier-suppressed double-sideband modulated optical signal with downlink transmission data among two input optical signals, and outputs an optical signal output from the optical modulator. As the downlink optical radio signal, after being combined with the optical carrier signal for uplink and an optical multiplexer, and configured to transmit to the radio base station,
The optical receiver is:
An optical multiplexer that combines the modulated optical signal transmitted from the radio base station and the polarization-combined optical signal output from the optical signal generator;
A light receiver that receives an optical signal combined by the optical multiplexer and outputs an electrical signal of the intermediate frequencies f _IF1 and f _IF2 ;
An electric detector for detecting electric signals of the intermediate frequencies f _IF1 and f _IF2 output from the light receiver;
An optical-radio fusion communication system comprising: a low-pass filter for low-pass filtering an output signal of the electric detector and outputting the upstream transmission data. The accommodation station is equipped with an optical signal generator, an optical transmitter and an optical receiver,
The optical transmitter transmits a downlink optical radio signal modulated with downlink transmission data and an optical carrier signal for uplink via an optical transmission path to a radio base station,
The radio base station bifurcates the received optical signal with an optical splitter, and receives a downlink radio signal (frequency f _RF-d ) obtained by receiving one output optical signal of the optical splitter to the wireless terminal. Transmitting, receiving a radio signal (frequency f _RF-u ) modulated with uplink transmission data, optically modulating the other output optical signal of the optical splitter with the received uplink radio signal, and modulating the optical signal To the accommodation station via an optical transmission line,
The optical receiver receives the modulated optical signal, detects and recovers the upstream transmission data in an optical-radio fusion communication system,
The optical signal generator is
A first single-spectrum light source that outputs a first single-spectrum optical signal (center frequency f _c1 );
A second single spectrum light source for outputting a second single spectrum optical signal (center frequency f _c2 );
A third single spectrum light source that outputs a third single spectrum optical signal (center frequency f _c3 );
An optical branching device that branches the optical signal of the first single spectrum in two, and a half value (f _RF− of the frequency f _RF-d of a desired downlink radio signal with respect to one output optical signal of the optical branching device. _an optical modulator for performing optical carrier suppressed double-sideband modulation with an electric carrier signal of _d / 2),
The polarization direction and light intensity of the second single-spectrum optical signal and the polarization direction and light intensity of the third single-spectrum optical signal are orthogonal and equal to each other. Polarization adjustment means for adjusting the light intensity and orthogonally combining the two waves and outputting them as a polarization combined optical signal;
The center frequencies f _c1 , f _c2 , and f _c3 of the first, second, and third single spectrum optical signals are set to the frequency f _RF-u and the predetermined intermediate frequencies f _IF1 and f _IF2 of the uplink radio signal, respectively. for,
| F _c1 −f _c2 | = f _RF−u ± f _{IF1
| F c1 -f c3 | = f} RF-u ± f IF2
Controlled to be
The carrier-suppressed double-sideband modulated optical signal is input to the optical transmitter, and the polarization combined optical signal is input to the optical transmitter as the uplink optical carrier signal, and the other output of the optical splitter It is configured to output an optical signal to the optical receiver,
The optical transmitter includes an optical modulator that optically modulates the carrier-suppressed double-sideband modulated optical signal with downlink transmission data among two input optical signals, and outputs an optical signal output from the optical modulator. As the downlink optical radio signal, after being combined with the optical carrier signal for uplink and an optical multiplexer, and configured to transmit to the radio base station,
The optical receiver is:
An optical multiplexer that combines the modulated optical signal transmitted from the wireless base station and the single-spectrum optical signal output from the optical signal generator;
A light receiver that receives an optical signal combined by the optical multiplexer and outputs an electrical signal of the intermediate frequencies f _IF1 and f _IF2 ;
An electric detector for detecting electric signals of the intermediate frequencies f _IF1 and f _IF2 output from the light receiver;
An optical-radio fusion communication system comprising: a low-pass filter for low-pass filtering an output signal of the electric detector and outputting the upstream transmission data. The optical-wireless fusion communication system according to claim 1 or 2,
The optical receiver, instead of the electric detector and the low-pass filter,
A filter that separates an electrical signal having an intermediate frequency f _{IF1 and} an electrical signal having an intermediate frequency f _IF2 output from the light receiver;
A first electric detector and a second electric detector that respectively detect an electric signal having an intermediate frequency f _{IF1 and} an electric signal having an intermediate frequency f _IF2 output from the filter;
An optical-radio fusion communication system comprising: an adder that adds the output signal of the first electric detector and the output signal of the second electric detector and outputs the transmission data. The optical-wireless fusion communication system according to claim 1 or 2,
The optical receiver, instead of the electric detector and the low-pass filter,
A filter that separates an electrical signal having an intermediate frequency f _{IF1 and} an electrical signal having an intermediate frequency f _IF2 output from the light receiver;
A first electric detector and a second electric detector that respectively detect an electric signal having an intermediate frequency f _{IF1 and} an electric signal having an intermediate frequency f _IF2 output from the filter;
A phase adjustment adder that outputs the transmission data by adding the phases of the output signal of the first electric detector and the output signal of the second electric detector in alignment with each other; Wireless fusion communication system. The optical-wireless communication system according to claim 1,
A plurality of radio base stations, a plurality of optical transmitters respectively transmitting a downlink optical radio signal and an uplink optical carrier signal to the plurality of radio base stations to the accommodating station, and transmitted from the plurality of radio base stations A plurality of optical receivers for receiving the modulated optical signals,
The optical signal generator is
A first optical branching device that branches the carrier-suppressed double-sideband modulated optical signal into a plurality of signals and inputs the plurality of signals to the plurality of optical transmitters;
A second optical branching device for branching the other output optical signal of the optical branching device into a plurality of optical signals and inputting them to the plurality of optical transmitters as the uplink optical carrier signal;
And a third optical branching device for branching the polarization multiplexed optical signal into a plurality of signals and outputting the branched signals to the plurality of optical receivers, respectively. The optical-wireless communication system according to claim 2,
A plurality of radio base stations, a plurality of optical transmitters respectively transmitting a downlink optical radio signal and an uplink optical carrier signal to the plurality of radio base stations to the accommodating station, and transmitted from the plurality of radio base stations A plurality of optical receivers for receiving the modulated optical signals,
The optical signal generator is
A first optical branching device that branches the polarization-multiplexed optical signal into a plurality of optical signals, and inputs the optical signals as uplink optical carrier signals to the plurality of optical transmitters;
A second optical branching device for branching the carrier-suppressed double-sideband modulated optical signal into a plurality of signals and inputting the signals to the plurality of optical transmitters;
An optical-wireless fusion communication system comprising: a third optical branching device that branches the other output optical signal of the optical branching device into a plurality of signals and outputs each of the signals to the optical receiver. The optical-wireless fusion communication system according to any one of claims 1 to 6,
The radio base station is
An optical branching device that splits the received optical signal into two branches, a light receiving device that receives one output optical signal of the optical branching device and converts it into a downlink radio signal, and another output optical signal of the optical branching device, Instead of an optical modulator that performs optical modulation with an upstream radio signal,
An optical-radio fusion communication system comprising an electroabsorption optical modulator that simultaneously receives received optical signals and performs optical modulation with upstream radio signals. The optical-wireless fusion communication system according to any one of claims 1 to 7,
The optical transmitter, the wireless base station, and the optical receiver are connected via a single-core optical transmission line,
A downstream optical signal transmitted from the optical transmitter to the accommodating station and the wireless base station, received by the wireless base station and converted into a downstream wireless signal, and transmitted from the wireless base station and received by the optical receiver An optical-radio fusion communication system comprising a bidirectional optical separator that separates an upstream optical signal. The accommodation station is equipped with an optical signal generator, an optical transmitter and an optical receiver,
The optical transmitter transmits a downlink optical radio signal modulated with downlink transmission data and an optical carrier signal for uplink via an optical transmission path to a radio base station,
The radio base station transmits a downlink radio signal (frequency f _RF-d ) obtained by receiving a downlink optical radio signal to a radio terminal, and a radio signal (frequency f _RF-u) modulated with uplink transmission data. ), Optically modulate the optical carrier signal for uplink with the received uplink radio signal, and transmit the modulated optical signal to the accommodating station via an optical transmission line,
In the optical-wireless fusion communication method in which the optical receiver receives the modulated optical signal, detects and reproduces the uplink transmission data,
The optical signal generator is
The first single-spectrum optical signal (center frequency f _c1 ) is branched into two, and the half value (f _RF-d / 2 ₎ of the frequency f _RF-d of the desired downstream radio signal with respect to one of the output optical signals. ) Is applied to the optical carrier signal, and the carrier-suppressed double-sideband modulated optical signal is input to the optical transmitter, and the other branched output optical signal is used as the uplink light. Input to the optical transmitter as a carrier signal,
The polarization directions of the second single-spectrum optical signal (center frequency f _c2 ) and the third single-spectrum optical signal (center frequency f _c3 ) are orthogonal to each other and have the same light intensity. A polarization-combined optical signal obtained by combining the waves with orthogonal polarization is output to the optical receiver,
The center frequencies f _c1 , f _c2 , and f _c3 of the first, second, and third single spectrum optical signals are set to the frequency f _RF-u and the predetermined intermediate frequencies f _IF1 and f _IF2 of the uplink radio signal, respectively. for,
| F _c1 −f _c2 | = f _RF−u ± f _{IF1
| F c1 -f c3 | = f} RF-u ± f IF2
Control to be
The optical transmitter performs optical modulation with downlink transmission data on the carrier-suppressed double-sideband modulated optical signal of two input optical signals, and uses the output optical signal as the downlink optical radio signal as the uplink optical signal. After combining with the optical carrier signal for link, transmit to the radio base station,
The optical receiver is:
The modulated optical signal transmitted from the radio base station and the polarization combined optical signal output from the optical signal generator are combined,
An optical signal characterized by detecting an electrical signal having intermediate frequencies f _IF1 and f _IF2 obtained by receiving the combined optical signal, and low-pass filtering the output signal to generate the upstream transmission data. Wireless fusion communication method. The accommodation station is equipped with an optical signal generator, an optical transmitter and an optical receiver,
The optical transmitter transmits a downlink optical radio signal modulated with downlink transmission data and an optical carrier signal for uplink via an optical transmission path to a radio base station,
The radio base station transmits a downlink radio signal (frequency f _RF-d ) obtained by receiving a downlink optical radio signal to the radio terminal, and a radio signal (frequency f _RF-u) modulated with uplink transmission data. ), Optically modulate the optical carrier signal for uplink with the received uplink radio signal, and transmit the modulated optical signal to the accommodating station via an optical transmission line,
In the optical-wireless fusion communication method in which the optical receiver receives the modulated optical signal, detects and reproduces the uplink transmission data,
The optical signal generator is
The first single-spectrum optical signal (center frequency f _c1 ) is branched into two, and the half value (f _RF-d / 2) of the desired downlink radio signal frequency f _RF-d with respect to one of the output optical signals. ) Is applied to the optical transmitter, and the carrier-suppressed double-sideband modulated optical signal is input to the optical transmitter, and the other branched output optical signal is input to the optical receiver. Output to
The polarization directions of the second single-spectrum optical signal (center frequency f _c2 ) and the third single-spectrum optical signal (center frequency f _c3 ) are orthogonal to each other and have the same light intensity. A polarization-combined optical signal obtained by combining the waves with orthogonal polarization is input to the optical transmitter as the uplink optical carrier signal,
The center frequencies f _c1 , f _c2 , and _fc 3 of the first, second, and third single spectrum optical signals are set to the frequency f _RF-u and the predetermined intermediate frequencies f _IF1 and f _IF2 of the uplink radio signal, respectively. for,
| F _c1 −f _c2 | = f _RF−u ± f _{IF1
| F c1 -f c3 | = f} RF-u ± f IF2
Control to be
The optical transmitter performs optical modulation with downlink transmission data on the carrier-suppressed double-sideband modulated optical signal of two input optical signals, and uses the output optical signal as the downlink optical radio signal. After combining with the optical carrier signal for link, transmit to the radio base station,
The optical receiver is:
The modulated optical signal transmitted from the wireless base station and the optical signal of the single spectrum output from the optical signal generator are combined,
An optical signal characterized by detecting an electrical signal having intermediate frequencies f _IF1 and f _IF2 obtained by receiving the combined optical signal and low-pass filtering the output signal to generate the upstream transmission data. Wireless fusion communication method. The optical-wireless fusion communication method according to claim 9 or 10,
The optical receiver is:
Separating the electrical signals of the intermediate frequencies f _IF1 and f _IF2 ,
_Detecting the electric signal of the intermediate frequency f _{IF1 and} the electric signal of the intermediate frequency f _IF2 ,
Each of the output signals is added to generate the transmission data. A combined optical-wireless communication method. The optical-wireless fusion communication method according to claim 9 or 10,
The optical receiver is:
Separating the electrical signals of the intermediate frequencies f _IF1 and f _IF2 ,
_Detecting the electric signal of the intermediate frequency f _{IF1 and} the electric signal of the intermediate frequency f _IF2 ,
The transmission data is generated by adding the output signals after aligning the phases of the output signals.

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