JPH029240A - Communication system - Google Patents

Abstract

PURPOSE:To simplify and economize the constitution of high speed data transmission and broad band signal transmission system by introducing the optical communication technology to the wired system in the communication network consisting of a central stationary station, plural relay stationary radio equipments and plural mobile radio terminal equipments being the combination of the radio system and the wire transmission. CONSTITUTION:A radio waves fT from a terminal equipment 1 received by a relay stationary radio equipment 10 is converted into an optical signal OT by an electrooptic converter EO12 via a high frequency circuit RF11 and sent to a central stationary station 16 via an optical fiber 14, synthesized with an optical signal from a wire system terminal equipment connected to the central control system 20 and an optical signal from other plural system by an optical multiplier 17. The multiplexed signal is subject to frequency conversion at the frequency band of a frequency fH from the frequency band of the radio frequency area fT by a conversion circuit 18 in the lump, becomes the optical signal OR while being converted again into light, distributed to the communication opposite party of the wired system connecting to the central control system 20 or the relay stationary radio equipment of the opposite communication by an optical distributer 19. The optical signal OR distributed to the relay stationary radio equipment 10 is converted into an electric signal by an optoelectric converter OE 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field to which the Invention Pertains) The present invention relates to a communication system using low power such as local area radio, and particularly relates to a communication method using a small power communication system such as a local wireless system, and particularly relates to a communication method using a plurality of relay fixed stations that are branch-connected to a central fixed station by optical fibers and arranged in a distributed manner. Multiple mobile wireless terminals that can move within a limited area (service area) of the wireless device and mobile wireless terminals in other service areas or wired terminals connected to a central fixed station The present invention relates to communication systems configured to communicate with each other.

(Prior art and its problems) Communication networks such as in-house communication and LAN are important technologies for future office automation (OA), factory automation (FA), and the like.

Traditionally, these communications have used wired transmission lines (communication lines) such as pair cables, coaxial cables, and optical fibers between central fixed stations and terminals, and the terminals have been fixed at specific locations. Common. Therefore, every time the layout within an office or factory is changed, it is necessary to reinstall the communication line, which is uneconomical.

For this reason, there is a strong desire to install mobile terminals that can be moved freely, such as cordless telephones, cordless data terminals, and terminals that can be remotely controlled by wireless methods. It's coming.

Communication systems that do not require the installation of a wired transmission line to meet such demands include (a) power line transport system, (b) optical space transmission system, and (c) wireless system. However, each method has the following problems. That is, in (a), the transmission band and reach are limited by the transmission frequency characteristics (loss) and noise characteristics of the power line. (b) is limited by the equipment installation conditions at a communication location due to the straightness of light, and both pose practical problems.

However, (c) is the most suitable communication method for the above purpose, although the transmission power used is limited by laws and regulations, so there is a limit to the reach.

As a conventional communication network that meets the above requirements, there is a communication network configuration that combines a wireless system and wired transmission as shown in FIG. Usually, a plurality of relay fixed wireless devices 2 are branch-connected to a central fixed station 7 via wires 6.
Although the entire network is composed of the relay fixed radio device 2 and one or more mobile radio terminals 1 that perform wireless transmission and reception, the example in Fig. 1 shows only one system in the case of one each. It is. In this case, the terminal device 1 sets a range in which the required communication quality can be maintained with limited transmission power as a unit service area, and connects the radio frequency circuit (RF) 3. m transformer 4. A relay fixed radio device 2 consisting of a baseband modem (MOD) 5 is placed in each unit service area for communication, and a baseband modem (MOD)
D)8. Generally, a network is configured such that a central fixed station 7 consisting of a central control system 9 and a wired line (not shown) having a plurality of terminals and a relay fixed radio device 2 are connected by a wire 6. However, in in-plant radio using low-power radio, the unit service area of relay fixed radio equipment 2 is limited to a radius of about 50 m, so in order to communicate with a large number of mobile radio terminals 1 in a large premises, it is necessary to , it is necessary to arrange a large number of relay fixed radio devices 2 in a distributed manner. On top of that,
In such a communication system, in order to communicate not only calls and simple data, but also high-speed data and images, cables and cables that can make the wire 6 and baseband modem 5, 8, etc. have a wider band and can transmit high-speed data are needed. equipment is required. This has the disadvantage that it not only requires technically sophisticated and complex equipment, but also requires the deployment of a large number of expensive relay fixed radios.

(Object of the Invention) The object of the present invention is to provide a communication system in which optical communication technology is introduced into a wired system in order to achieve structural simplification and economicalization of high-speed data transmission and broadband signal transmission systems in such communication networks. The goal is to provide a method.

(Structure of the Invention) In the communication system according to the present invention, a plurality of relay fixed radio devices branch-connected by optical fibers from an optical modulation frequency conversion device in a central fixed station are distributed and connected via an interface circuit in the central fixed station. A plurality of wired lines are connected to each other, and each of the plurality of mobile radio terminals in each service area is connected to other terminals or The plurality of relay fixed radio devices are configured to communicate with each other using arbitrary terminals on the plurality of wired lines as communication partners, and the plurality of relay fixed radio devices use frequency band signals of radio waves received from the mobile radio terminals as modulated waves. The interface comprises: an electrical/optical converter that performs optical intensity modulation to produce a first optical signal; and an optical/electrical converter that converts the optical intensity modulated third optical signal into the frequency band signal of the radio wave; The circuit includes a radio device that converts a baseband signal from the wired line into a frequency band signal of the radio wave, and an electric/wireless device that modulates the intensity of light using the frequency band signal of the radio wave as a modulation wave to generate a second optical signal. an optical converter; and an optical/electrical converter that converts a fourth optical signal modulated in optical intensity into the frequency band signal of the radio wave, an optical combiner that combines the second optical signal with a second optical signal; an optical/electrical converter that converts the output of the optical combiner into the frequency band signal of the radio wave; and a frequency interval between the converted frequency bands so that they do not affect each other. a converter circuit consisting of a mixer that converts the frequency of the frequency-converted electric signal and an electric/optical converter that modulates the optical intensity of the frequency-converted electric signal as a modulated wave; and outputs of the converter circuit as the third and fourth optical signals. an optical distributor that distributes to the plurality of fixed relay radio devices and the interface circuit; and a control system that controls the third and fourth optical signals from the optical distributor to be distributed to desired communication partners. It is characterized by the fact that it is equipped with

This will be explained in detail below with reference to the drawings.

FIG. 2 shows an embodiment of a communication system showing an overview of the communication network configuration according to the present invention, and FIG. 3 shows a frequency spectrum for explaining frequency conversion in the communication system. FIG. 2 shows only one system in which a plurality of relay fixed wireless devices 10 are arranged radially around a central fixed station 16 in a distributed manner using optical fibers. In the figure, a radio wave f7 from a terminal device 1 received by a relay fixed radio device 10 passes through a radio frequency circuit (RF) 11 to an electrical/optical converter (EO).
) 12 performs intensity modulation of the light and converts it into an optical signal OT. The optical signal 0. is transmitted to the central fixed station 16 via the optical fiber 14, and is combined with optical signals from other multiple systems and optical signals from wired terminals (not shown) connected to the central control system 20 at the optical combiner 17. Combined (linear addition)
.

In this case, the radio signal fT from each terminal 1 is frequency-divided and time-divided to prevent mutual interference.

Multiplexed using code division, etc. In the frequency spectrum shown in FIG. 3, modulated wave signals O, l in the optical domain.

0, and radio frequencies fR, f in the radio wave region correspond to each other.

The signals combined by the optical combiner 17 are collectively sent to the conversion circuit 1.
8 in the radio frequency domain from the ft frequency band to r.

It undergoes frequency conversion to a frequency band of 0.0, and is converted back to light and becomes an optical signal of 0. becomes. This optical signal OR is distributed by the optical distributor 19 to each communication partner, that is, a wired communication partner connected to the central control system 20 or a relay fixed wireless device of the communication partner in another service area. . The optical signal distributed to the relay fixed radio device 10 (corresponding to the relay fixed radio device in which the mobile terminal of the communication partner exists within its service area) is converted into an electrical signal by an optical/electrical converter (OE) 13. The signal is converted into a radio signal f through the high frequency circuit 11, and then radiated from the antenna toward the communication partner's terminal.

If this method is adopted, the wired transmission system including the baseband modem will be greatly simplified compared to the conventional configuration shown in Figure 1.
It is easy to understand that high-speed transmission is possible. Moreover, since optical fibers have low transmission loss and are less susceptible to electromagnetic interference, a major feature of the present invention is that it facilitates the construction of a network having a large number of unit service areas within a large premises.

In FIG. 2, the multiplex communication system between the mobile radio terminal l and the fixed radio equipment 10 is, for example, CDMA=Code.
Division Multiple Access
,,TDMA=TiIIIle Division MA
, F DMA= Frequency D 1vi
The frequency spectrum of this multiplex communication signal, which may be in any format such as sion MA, is based on the transmission frequency band f7 as shown in Fig. 3, assuming simultaneous two-way communication.
and reception frequency band f are clearly separated with a difference in frequency f, so as not to affect each other, and frequency conversion from transmission frequency band fT to reception frequency band f, I is easy. It is set to a certain frequency arrangement.

FIG. 4 shows an embodiment of the circuit configuration of the main parts of the relay fixed radio device and the central fixed station of the communication system according to the present invention.

In the figure, 30 (R,, Rt...Rs) is a mobile radio terminal, and 31 (B+, Bz...BM) is a fixed relay radio that has the function of converting radio frequencies into optical signals and optical It has the function of converting signals to radio frequencies.

The central fixed station connected to this relay fixed radio device 31 by optical fibers 21 and 22 has an optical modulation frequency converter 32 and a central control system 20 as its main parts, and a wired system line 36 is connected to the central control system 20. Each has a wired terminal (not shown).

The optical modulation frequency conversion device 32 includes the optical combiner 17. Conversion circuit 1
8 and an optical distributor 19, and a central control system 20
is composed of an interface circuit 34 and a control system 35.

The interface circuit 34 converts an optical signal flowing through the optical fiber 2L 22 connected to the optical modulation frequency conversion device 32 and a baseband electric signal flowing through the wired line 36.
A 4-wire hybrid transformer (H) 50, a mobile radio terminal 30 that converts a baseband signal into a radio frequency band fA+fR, a radio device (C) 49 having inter-route performance, and an electrical/optical converter (EO). ) 47 and optical/electrical converter (OE
) 48.

The control system 35 connects the controller 52, the radio device (C) 49, and the
Radio (D) 51 and EO47, 0E48 with the performance of
It is composed of. Reference numeral 37 denotes a control line to which a control signal is input from the wired system.

Next, the details of the operation will be explained with reference to FIG.

A plurality of mobile radio terminals (Rl, R!...RH) are connected to terminal equipment (not shown) such as telephones and data terminals used by users, and the information to be transmitted is transmitted by radio waves. Convert to fixed radio equipment (B,,B.

...BM) 31.

The relay fixed radio device 31 differs from a normal radio device in that it has a high frequency section consisting of an antenna, a duplexer (DUP) 39, and an amplification section, and an electrical/optical converter (EO) 12° and an optical/electrical converter (OE) 13. It is composed of.

Further, the desired total service area is divided into unit service areas determined by radio wave reach, and one relay fixed radio device is distributed and arranged in each unit service area.

When the relay fixed radio equipment receives the transmission radio wave f7 from the mobile radio terminal 30, the radio signal fa is converted into an optical signal OT whose intensity is modulated in the converter (EO) 12, and is output to the optical fiber 21. . That is, in the present invention, radio waves are used for communication between the mobile terminal 30 and the relay fixed wireless device 31 of the network, and optical fibers 21 and 22 are used as communication media within the network. Moreover, the signal transmitted to this optical fiber 21 is an optical signal modulated by radio waves.

As mentioned above, the transmission signal f from the terminal device 1 to the network is converted into an optical signal Oa by each fixed radio device 31, and transmitted to other systems and wired by the optical combiner 17 of the central fixed station via the optical fiber 21. Combination (addition) with optical signal from system line 36
be done. The optical signal 0 of the optical combiner J7 is once converted into a radio frequency band electric signal f by the optical/electrical converter (OE) 42 in the conversion circuit 18, and then modulated by the local oscillator 44 by the mixer (MIX) 43. The wave fA (radio frequency) undergoes frequency conversion and is converted into a reception radio frequency band fR, which is separated by f from the transmission radio frequency band fT. This signal is transferred to an electrical/optical converter (E
If optical detection is performed at O) 45, an optical signal O1I for reception radio will be obtained. The converted optical signal OR is sent to optical splitter 1
9 and is distributed to each relay fixed radio device 31 and interface circuit 34 via the optical fiber 22.

At this time, the exchange function for the optical distributor 19 is performed by the optical control signal sent from the controller 52 via the EO 53. In the fixed radio device 31, the optical signal Oi is detected by the converter (OE) 13, and the radio signal fR is radiated from the antenna to transmit the signal from the network to the mobile terminal 30.

In the interface circuit 34, the distributed optical signal is 0E.
48, it is converted to the radio frequency band flI, and then the radio 4
At step 9, the signal is converted into a baseband signal and output to the wired line 36 via the hybrid transformer 50.

The controller 52 converts the optical signal obtained from the optical splitter 19 through the optical fiber 23 into 0E48. The line is controlled by a signal converted to baseband by the radio device 51 and a wired system control signal from the control line 37. Its main functions are as follows.

i) Detection function of network access from mobile terminal 30 and wired line 36.

ii) Dynamic channel allocation function for mobile terminal 30 and wired line 36. In other words, it is a function that allocates channels according to line conditions without fixing them.

ii) Network monitoring functions.

iv) Other necessary control functions.

Control signals for performing these functions are converted into optical signals by the EO converter 53 and applied to the optical distributor 19.

Moreover, it can also be given to the light combiner 17 via the radio device 51 and the EO 47.

The above embodiment can also be modified as follows.

a) In the embodiment, a star-shaped (radial) network configuration is shown in which the optical fibers 21.22 are centered around a central fixed station, but the optical combiner 17. By adding the conversion circuit 18 and the optical distributor 19 to the fixed radio device 31 side, a loop type (annular type) network configuration can be easily realized.

b) It is also possible to prepare one light source as a system, and configure the transmission side by distributing this light source and modulating external light. This configuration is advantageous in order to prevent interaction between the optical signals of each relay fixed radio device.

C) The example uses a passive optical combiner and an optical distributor, but if there are a large number of distributed fixed radio devices 31, an active optical combiner and an optical distributor that can compensate for the combining loss and distribution (ignition) may be used. It is also possible to make the system configuration (loss allocation) advantageous by using the device.

d) By applying optical wavelength multiplexing, the amount of optical fiber used can be reduced.

(Effects of the Invention) As described above in detail, according to the present invention, the wired transmission system can be simplified and the system can be made more economical. Also,
The service area can be expanded economically by using optical fiber (low loss), and the system can be expanded economically by adding the same subsystem (fixed radio equipment).

By applying optical transmission technology, it becomes easier to widen the frequency band of the system, increase the amount of information, and expand from voice communication to image communication, and its effects are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the configuration of a conventional communication network, FIG. 2 is a block diagram showing an example of the configuration of the communication network of the present invention, FIG. 3 is a frequency spectrum diagram, and FIG. 4 is an embodiment of the present invention. It is a circuit block diagram showing. 1.30...Terminal device, 2.10.31...Relay fixed radio device, 3.11...High frequency circuit, 4...Converter, 5.8...Baseband modem, 6. ...Wired transmission line, 7.16...Central fixed station, 9.20...
Central control system, 12, 45.47.53... Electrical/optical converter (EO), 13, 42.48... Optical/electrical converter (OE), 14, 15.21.22.23. 24...
Optical fiber, 17... Optical combiner, 18... Conversion circuit, 19... Optical distributor, 32... Optical modulation frequency conversion device, 34... Interface circuit, 35.
...Control system, 36...Wired system line, 37...
Wired system control line, 39... Duplexer, 43...
・Mixer, 44...Local oscillator, 49°51...
・Radio device, 50... 2-wire-4-wire hybrid transformer, 52... Controller.

Claims (1)

[Scope of Claims] A plurality of relay fixed wireless devices branched and connected by optical fibers from an optical modulation frequency conversion device in a central fixed station are distributed and connected to a plurality of wired lines via an interface circuit in the central fixed station. are connected, and each of the plurality of mobile radio terminals in each service area is connected to other terminals in the same service area or in another service area or the plurality of wired lines by the radio waves of the plurality of relay fixed radios. The plurality of relay fixed wireless devices are configured to communicate with each other using any terminal device as a communication partner, and the plurality of relay fixed wireless devices perform optical intensity modulation using the frequency band signal of the radio wave received from the mobile wireless terminal device as a modulating wave. an electrical/optical converter that converts a third optical signal into the radio wave frequency band signal; a radio device that converts a baseband signal from a line into a frequency band signal of the radio wave; an electrical/optical converter that modulates the optical intensity using the frequency band signal of the radio wave as a modulation wave to generate a second optical signal; an optical/electrical converter that converts the intensity-modulated fourth optical signal into the frequency band signal of the radio wave; an optical/electrical converter that converts the output of the optical synthesizer into the radio frequency band signal; and a mixer that converts the frequency of the converted frequency bands at frequency intervals that do not affect each other. and an electric/optical converter that modulates optical intensity using the frequency-converted electric signal as a modulated wave; and the plurality of relay fixed radios using the output of the conversion circuit as the third and fourth optical signals. and an optical distributor that distributes the third and fourth optical signals from the optical distributor to a desired communication partner. communication method.