JPH07177556A - Mobile radio communication system - Google Patents

Abstract

PURPOSE:To simplify, a control station and a base station, to make the size of them small and to reduce the cost by arranging a light source only to a control station at a start point of a transmission line. CONSTITUTION:An optical fiber cable 25 forms a loop from a control station 5 and to the control station 5 via base stations 101-10n sequentially, and a light source for the optical fiber cable 25 is installed in an electrooptic converter 6 of the control station 5, each of the base stations 101-10n is provided with a photoelectric converter 11 converting an optical signal branched from the optical fiber cable 25 into an electric signal and with an optical modulator 39 modulating the optical signal through the optical fiber cable 25 with the electric signal, and the control station 5 is provided with an optoelectric converter 7 converting the optical signal coming circulated through the optical fiber cable 25 into an electric signal. Then the transmission reception wavelength of the optical signal for the control station 5 an each of the base stations 101-10n is allocated in wavelength division and he optical signals among the base stations 101-10n are not interfered with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used to construct a communication network in which one control station and a plurality of base stations are connected by a network. In particular, the present invention relates to a technique for simplifying and downsizing the configurations of a control station and a base station and reducing the equipment cost thereof. INDUSTRIAL APPLICABILITY The present invention can be used in local area networks and other optical communication systems.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIGS. FIG. 7 is an overall configuration diagram of a conventional example. FIG. 8 is a block diagram of a conventional control station and base station. In the conventional mobile radio communication system, as shown in FIG. 7, the control station 5 and the base station 10 are connected one to one, or the control station 50 and the base stations 10 ₁ to 10 _n are connected one to n. It At this time,
Two optical fiber cables 8 and 8 ₁ to 8 _n for upstream signals and two optical fiber cables 9 and 9 _{1 to} 9 _n for downstream signals are required.

As shown in FIG. 8, the control station 5 comprises a signal input port 1, a frequency synthesizer 3, an electro-optical converter 6, an opto-electric converter 7, a frequency demultiplexer 4 and a signal output port 2. There is. On the other hand, the base station 10 includes an opto-electric converter 11, an electro-optical converter 12, high frequency amplifiers 13 and 14, a transmission / reception separator 15, and a radiator 16. Further, the mobile station 20 is connected to the base station 10 by the wireless line 17.

There is widely known an optical local area network in which an optical transmission line is formed in a loop shape and a plurality of slave station devices are connected to this loop-shaped optical transmission line. In this conventional optical local area network, the slave station device branches an optical signal from this optical transmission line to convert it into an electric signal, and also converts the electric signal containing the information generated in the slave station device to an optical signal and again It was optically coupled to the optical transmission line.

[0005]

Due to such a configuration, the control station has two optical fiber cables for each base station, an electro-optical converter, an opto-electric converter, a frequency multiplexer, and a frequency multiplexer. A duplexer is needed. The larger the number of base stations, the larger the number of these components prepared by the control station.
As a result, the installation cost of the control station becomes enormous.

The present invention has been made in view of such a background, and simplifies and downsizes a control station, and makes it economical and inexpensive, and further simplifies and downsizes a base station. It is an object of the present invention to provide a mobile wireless communication system that can be economically improved.

[0007]

The present invention is characterized in that the light source is arranged only in the control station which is the starting point of the optical transmission line, and the light source is not arranged in each base station.

According to a first aspect of the present invention, a control station, a plurality of base stations controlled by the control station, a mobile station connected to the base station by a radio line, and the plurality of base stations are provided. It is a mobile radio communication system provided with one optical transmission line connected to a control station.

Here, a feature of the present invention is that the optical transmission line forms a loop from the control station to the control station via the plurality of base stations in sequence, The light source is in the control station, and each base station has an opto-electric converter for converting an optical signal branched from the optical transmission line into an electric signal, and an optical signal for modulating the optical signal passing through the optical transmission line with the electric signal. A modulator is provided, and the control station is provided with an opto-electric converter that converts an optical signal that circulates through the optical transmission path and arrives into an electrical signal.

Transmission / reception timings of the control station and each base station are preferably assigned in a time division manner. Also,
The transmission / reception wavelengths of the control station and each base station may be allocated in a wavelength division manner.

A second aspect of the present invention is an optical communication system in which one master station and a plurality of slave stations communicating with the master station are connected in a loop by one optical transmission line.

A feature of the present invention is that the light source of the optical transmission line is in the master station, and each slave station has an opto-electrical device for converting an optical signal branched from the optical transmission line into an electric signal. A converter and an optical modulator that modulates an optical signal that passes through this optical transmission line with an electrical signal are provided, and the optical signal that arrives at the main station after making a round of this optical transmission line is converted into an electrical signal. It is equipped with a photoelectric converter.

An optical branch circuit provided on an optical transmission line passing therethrough, an optoelectric converter provided at a branch output of the optical branch circuit, and an optical modulator inserted at the output of the optical branch circuit are provided. Is desirable.

[0014]

Although the light source is arranged in the control station, the light source is not arranged in each base station, so that the structure is simplified and the power consumption of the base station is reduced.

Since the control station and the plurality of base stations are connected in a loop by a single optical transmission line, it is necessary to provide the control station with electric-optical converters and opto-electric converters as many as the number of base stations. There is no. Therefore, the number of parts can be significantly reduced as compared with the conventional example. That is, the control station only needs to include an opto-electric converter and an electro-optical converter corresponding to one optical fiber cable.

Since one optical fiber cable is used for both transmission and reception, the base station can be simplified. That is, the base station branches a part of the optical signal from the optical fiber cable. Also, most of the optical signal is terminated as it is as an optical carrier by the control station via the subsequent base station. A part of the branched optical signal is converted into an electric signal and emitted from the antenna. The base station also modulates the optical carrier with the radio signal received from the mobile station. This optical carrier comes from the control station and does not require a light source at the base station. Further, since the transmitting / receiving branching filter is removed by using the transmitting and receiving radiators for the mobile station, the base station can be greatly simplified, downsized, and economically implemented.

The optical signal from the control station to each base station is transferred by multiplexing the optical signal addressed to each base station. The multiplexing method may be time division multiplexing or wavelength division multiplexing. The multiplexed optical signal is separated at each base station, and only the optical signal related to the own base station is extracted. As for the separation method, when wavelength-division-multiplexed, only the optical signal of the desired wavelength may be extracted from the optical signal, or all the optical signals may be converted into electrical signals for the time being and only the electrical signal of the desired frequency may be extracted. May be. When time-division-multiplexed, only the optical signal contained in the frame of the predetermined timing may be taken out as the optical signal addressed to the own base station and photoelectrically converted, or all the optical signals may be converted into electric signals for the time being. After that, the electric signal included in the frame addressed to the own base station may be extracted. This electric signal is high frequency amplified and transmitted to the mobile station as a radio signal.

The radio signal received from the mobile station is high frequency amplified. Most of the optical signals coming from the control station are terminated as they are in the control station via the subsequent base station as described above. The optical signal returned to the control station is used as an optical carrier to directly intensity-modulate the electric signal received from the mobile station. In this method, an optical waveguide of an optical carrier is provided in a substance exhibiting an electro-optical effect, and a high-frequency amplified electric signal is applied to this substance to change the refractive index due to the electro-optical effect, thereby performing intensity modulation on the optical carrier. be able to. If the reception frequency from the mobile station is made different in each base station, the control station can receive the signal from the desired base station by frequency separation. In addition, the frequency of the radio signal used for transmission and reception may be determined in advance in each base station. Furthermore, in the optical transmission line between each base station,
An optical amplifier may be inserted to supplement the optical carrier that is branched and attenuated at each base station.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is an overall configuration diagram of the first embodiment of the present invention.

[0020] The present invention includes a control station 5, and the base station 10 ₁ to 10 _n are controlled to the control station 5, the base station 10 ₁
Mobile stations 20 _{1 to} 20 connected to 10 _n by a wireless line
_The mobile radio communication system includes _n and an optical fiber cable 25 as one optical transmission line that connects the base stations 10 ₁ to 10 _n to the control station 5.

Here, a feature of the present invention is that the optical fiber cable 25 is provided from the control station 5 to the base stations 10 ₁ ...
A loop is formed to reach the control station 5 via 10 _n in sequence, the light source of the optical fiber cable 25 is in the electro-optical converter 6 of the control station 5, and each base station 10 ₁ to 10 _n receives this optical signal. An optical-electrical converter 11 for converting an optical signal branched from the fiber cable 25 into an electric signal, and an optical modulator 3 for modulating the optical signal passing through the optical fiber cable 25 with the electric signal.
9 and the control station 5 is provided with the optical fiber cable 2
It is provided with an opto-electrical converter 7 for converting an optical signal that arrives after making a round of 5 into an electric signal. The transmission / reception wavelengths of the optical signals of the control station 5 and the base stations 10 ₁ to 10 _n are assigned in a wavelength division manner so that the optical signals between the base stations 10 ₁ to 10 _n do not interfere with each other. Specifically, the optical-electrical converter 11 and the optical modulator 39 are configured to selectively perform optical-electrical conversion or optical modulation only on the assigned wavelengths.

An optical fiber cable 25 is used for the control station 5.
What is the base station 10₁-10_nAre connected. Mobile station 2
0₁~ 20_nAnd base station 10₁-10_nIs by wireless link
Connected to each other. Optical fiber cable 25
Many base stations 10₁-10_nBecause it can accommodate
It is economical. In addition, the control station 5 and the optical fiber cable 2
5, an electro-optical converter and an opto-electric interface
Only one converter is required, simplifying the control station 5.
To be effective. Further, the electro-optical converter of the control station 5
The light source installed in the base station 10₁-10_nCommonly used in
Therefore, the base station 10₁-10_nLight for electrical light conversion
It is not necessary to prepare a source, and the base station 10₁ -10_nEconomy of
And the economy of the entire system can be achieved.
Also, since the signal transmission line is the optical fiber cable 25,
Since it is a wideband transmission line, it can be used in a wide frequency band.
Transmission of barrel subcarrier frequency (microwave to millimeter wave)
There are advantages. Therefore, each base station 10₁-10_nTo
If you design for wideband signal conversion,
Information amount to the base station 10₁-10_nIn the zone covered by
Mobile station 20₁~ 20_nCan be supplied to.

Next, the operation of the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram of the control station 5 and the base stations 10 ₁ to 10 _n according to the first embodiment of the present invention. Here, the operation will be described assuming that the control station 5 and the base station 10 ₁ are connected one-to-one by the downlink by the optical fiber cable 8 and the uplink by the optical fiber cable 9 for the sake of easy understanding. The optical signal from the control station 5 is partially branched by the optical branch circuit 36, converted into a high frequency signal by the photoelectric converter 11, and the radio signal 42 is radiated to the radio zone through the high frequency amplifier 38 and the radiator 16 ₁ . On the other hand, the optical modulator 39 includes the radiator 16
_The received signal 43 arriving at ₂ modulates the optical carrier from the optical branch circuit 36. This modulated optical carrier is transmitted to the control station 5 via the uplink by the optical fiber cable 9.
Is terminated. As described above, the optical devices of the base station 10 ₁ are only the optical branch circuit 36, the photoelectric converter 11, and the optical modulator 39, and the optical signal can be transmitted to the control station 5 without requiring a light source. ₁ Furthermore, it has a great effect on simplifying the entire system and making it economical.

Next, the overall operation of the first embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram of the first embodiment device of the present invention. Optical branch circuit 3 of base station 10 _1.
The optical signal from the electro-optical converter 6 of the control station 5, which is partially branched at 6, is transmitted to the subsequent base station 10 ₂ via the optical fiber cable 44 as an optical carrier. Base station 10 ₂
Also branches a part of the optical signal in the same manner as the base station 10 ₁ at, and transmits the split optical signals to the mobile station to a radio signal by photoelectric conversion, a direct optical carrier by receiving signals from the mobile station It is modulated and transmitted to the subsequent base station 10 _n . By repeating this, the optical carrier is finally terminated in the receiving portion of the control station 5, and the control station 5 separates the radio signal received by the base stations 10 ₁ to 10 _n by the frequency demultiplexer 4 to output the signal output port 2. Output more.

Next, the optical modulator 39 will be described with reference to FIG. FIG. 4 is a diagram showing a circuit including the optical modulator 39.
A part of the optical signal from the control station 5 is branched by the optical branch circuit 36 via the optical fiber cable 8. The branched signal is converted into a radio signal by a photodetector (not shown; it is assumed to be formed on the back surface of the substrate in FIG. 4) formed on the semiconductor substrate 51, and a high frequency amplifier (not shown).
4 is amplified on the back surface of the substrate) and electromagnetically coupled to the radiator 16 ₁ (slot antenna) on the upper surface of the semiconductor substrate 51 from the back surface of the substrate and radiated as a transmission radio signal 53 in the space. The optical signal is directly incident on the optical detector from the optical fiber cable 80 through a condenser lens or an optical waveguide formed in the semiconductor substrate 51. In addition to the slot antenna, a microstrip antenna can be used to radiate a radio signal into space. Further, in FIG. 4, light reception and radiation use both surfaces of the semiconductor substrate 51, but it is also possible to form only one surface.

Most of the optical signals branched by the optical branch circuit 36 are incident on the electro-optical effect substrate 54 made of a substance exhibiting the electro-optical effect as optical carriers. An optical waveguide 55 and a microstrip antenna 56 are formed on the electro-optical effect substrate 54. Light intensity modulator 60
Is constructed by bifurcating the optical waveguide and synthesizing again at an appropriate length. The antenna 56 also serves as an electrode of the light intensity modulator 60, and changes the phase of the light wave signal of the optical waveguide in which the received wireless signal 52 is branched into two. As a result, the intensity of the combined light in the optical waveguide 57 is modulated, and the intensity-modulated output is obtained from the optical fiber cable 58. The basic principle of this modulation is the same as that of the conventional Mach-Zehnder type optical intensity modulator. Since the radio signal frequencies of transmission and reception are sufficiently separated, there is no interference between the transmission and reception radio signals. The output is input to the next base station via the optical fiber cable 58 or is terminated to the control station 5. Each base station 10 ₁ to 10 _n
Since the reception frequencies are different, there is little interference between the reception frequencies.

A second embodiment of the present invention will be described with reference to FIG. FIG. 5 is an overall configuration diagram of the second embodiment of the present invention. Radio transmission frequency group synthesized in the control station 5 is transmitted through the optical fiber cable 8 with intensity-modulated optical carriers in electrooptic converter 6 to each base station 10 ₁ to 10 _n. Since all frequency groups are included on the optical carrier, each base station 10
_If it is detected and emitted as it is at ₁ to 10 _n , all frequency groups will be emitted. Therefore, each base station 10
_1-10 provided each frequency separation circuits in _n, advance allocation using frequency that can be used in each base station 10 ₁ to 10 _n. The transmission frequency band of the base station 10 ₁ is, for example, f1
Up to f10, and the base station 10 ₂ assumes f11 to f20. On the other hand, the reception frequency bands of the base stations 10 ₁ to 10 _n are, of course, different from the transmission frequency band, and since the same optical carrier is used, the base stations 10 ₁ to 10 _n use different reception frequency bands. There is a need. Therefore, the base station 10 ₁ has fr1 to fr10, and the base station 10 ₂ has fr1.
1 to fr20. All reception frequencies are converted into electric signals by the photoelectric converter 7 via the optical fiber cable 9, and further output by the frequency demultiplexer 4 for each reception frequency band. It is possible to repeatedly use the same transmission frequency band depending on the installation conditions of the base stations 10 ₁ to 10 _n to be used, and it is possible to effectively use the frequency with a simple wireless distribution system. A specific frequency setting method can be realized by providing the high frequency amplifiers 13 and 14 of the base stations 10 ₁ to 10 _n with a filter 62 as frequency selecting means. High frequency amplifier 13
Alternatively, the filter 62 may be provided before or after 14 and 14.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is an overall configuration diagram of the third embodiment of the present invention. In the third embodiment of the present invention, the optical amplifier 75 is used as the base station 10.
_{It is} inserted in the optical fiber cable 25 between ₁ to 10 _n to compensate for the loss of optical carrier gain due to the optical branching in each base station 10 ₁ to 10 _n .

In the first to third embodiments of the present invention, the transmission / reception wavelengths of the optical signals in the control station 5 and the base stations 10 ₁ to 10 _n are assigned in a wavelength division manner, and explanation is given using the concept of wavelength multiplexing. However, the transmission / reception timing of the optical signal may be allocated in a time division manner, and the concept of time division multiplexing may be used.

[0030]

As described above, according to the present invention,
The control station can be miniaturized, simplified, and economically inexpensive, and the base station can be further miniaturized, simplified, and economical.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 2 is a block diagram of a control station and a base station according to the first embodiment of the present invention.

FIG. 3 is a block configuration diagram of a first embodiment device of the present invention.

FIG. 4 is a diagram showing a circuit including an optical modulator.

FIG. 5 is an overall configuration diagram of a second embodiment of the present invention.

FIG. 6 is an overall configuration diagram of a third embodiment of the present invention.

FIG. 7 is an overall configuration diagram of a conventional example.

FIG. 8 is a block diagram of a conventional control station and base station.

[Explanation of symbols]

1 signal input port 2 signal output port 3 frequency multiplexer 4 frequency demultiplexer 5, 50 control station 6, 12 electro-optical converter 7, 11 opto-electric converter 8, 9, 25, 44, 45, 58, 80 optical fiber cable 10, 10 ₁ to 10 _n base stations 13 and 14 high frequency amplifier 15 transmit-receive splitter 16, 16 _1, 16 ₂ radiator 17,42,43 radio signals 20, 20 ₁ to 20 _n mobile station 36 an optical branching circuit 39 Optical Modulator 51 Semiconductor Substrate 52 Received Radio Signal 53 Transmitted Radio Signal 54 Electro-Optical Effect Substrate 55, 57 Optical Waveguide 56 Antenna 60 Optical Intensity Modulator 62 Filter 75 Optical Amplifier

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H04Q 7/30 H04B 10/20

Claims (5)

[Claims] 1. A control station, a plurality of base stations controlled by the control station, a mobile station connected to the base station by a radio line, and one connecting the plurality of base stations to the control station. In the mobile radio communication system including the optical transmission line, the optical transmission line forms a loop from the control station to the control station through the plurality of base stations in sequence, and the light source of the optical transmission line. Is in the control station, and each base station has an opto-electric converter for converting an optical signal branched from the optical transmission line into an electric signal, and an optical modulation for modulating the optical signal passing through the optical transmission line with the electric signal. The mobile radio communication system according to claim 1, wherein the control station is provided with an opto-electric converter that converts an optical signal that circulates through the optical transmission path into an electric signal. 2. The mobile radio communication system according to claim 1, wherein transmission / reception timings of the control station and each base station are assigned in a time division manner. 3. The mobile station wireless communication system according to claim 1, wherein transmission / reception wavelengths of the control station and each base station are allocated in a wavelength division manner. 4. In an optical communication system in which one master station and a plurality of slave stations communicating with this master station are connected in a loop by one optical transmission path, the light source of the optical transmission path is the main station. Each of the slave stations has an opto-electric converter that converts an optical signal branched from this optical transmission line into an electric signal, and an optical modulator that modulates the optical signal passing through this optical transmission line with the electric signal. An optical transmission system, characterized in that the main station is provided with an opto-electrical converter for converting an optical signal arriving once around the optical transmission path to an electric signal. 5. An optical branch circuit provided in an optical transmission line passing therethrough, an opto-electric converter provided at a branch output of the optical branch circuit, and an optical modulator inserted at the output of the optical branch circuit. The slave station device for an optical transmission system according to claim 4, further comprising: