JP3300552B2 - Repeater using optical cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repeater provided as a countermeasure for blind spots in portable telephones and automobile telephone systems, and more particularly to a repeater utilizing optical analog transmission.

[0002]

2. Description of the Related Art For example, a portable telephone system comprises an exchange connected to a telephone network, a plurality of radio base stations connected to the exchange via inter-office communication lines, and a large number of portable telephones. ing. When the calling number of the mobile phone is dialed from the telephone, a radio wave is transmitted from the wireless base station in the service area, and the corresponding mobile phone is called and the user can make a mutual call. In order to further improve the services of such mobile phone systems, repeaters are installed in blind zones where radio waves do not reach, such as in premises, underground malls, and tunnels, and radio waves from wireless base stations are relay-amplified and used in blind zones. It has become possible to communicate with mobile phones (mobile devices).

FIG. 3 is a block diagram of a relay apparatus 2 to which the present invention is applied. In the figure, 1 is a radio base station,
31 is a wireless unit, 32 is an electric / optical converter (E / O) for converting an electric signal into light, 33 is a distributor, 5 is an optical cable,
Denotes a plurality of slave units, 34 denotes an optical / electrical converter (O / E) for converting light into an electric signal, 40 denotes a combiner, and 3 denotes a master unit. 6
-1 to 6-n are wireless zones. As shown in the figure,
The relay device 2 includes a master unit 3, a plurality of slave units 4-1 to 4-n, and an optical cable 5 connecting the slave units 4-1 to 4-n. Radio unit 3
1 receives a radio wave from the wireless base station 1 and outputs an amplified high-frequency signal (RF signal). The RF signal output from the wireless unit 31 is converted into light whose intensity is modulated by an E / O converter 32 using a light emitting diode such as a semiconductor laser diode, and distributed to a plurality of slave units 4 by a distributor 33. You. The plurality of slave units 4 are provided in the respective zones 6-1 to 6-1.
According to 6-n, the entire area such as the premises of a blind zone, an underground shopping mall, or a tunnel is set as a service area.
They are distributed over a range of up to 20 km. The connection between the plurality of slave units 4 and the master unit 3 has a low loss (0.3 dB / km).
〜0.5 dB / km), and optical analog transmission is employed.

The plurality of slave units 4 are provided with an O / E converter for directly detecting the intensity-modulated light, and a radio unit for amplifying an output RF signal and transmitting the amplified RF signal from an antenna. A transmission wave from a mobile unit (mobile phone) in the wireless zone 6 of the slave unit 4 is received and amplified by the wireless unit via the antenna of the slave unit 4, and is intensity-modulated by the E / O converter similarly to the master unit. The light is converted to light and sent from the slave unit 4 to the master unit 3 via the cable 5 together with the monitoring data, and is converted into an optical / electrical converter (O / E).
The signal is converted into an electric signal by 34, synthesized by the synthesizer 40, and input to the radio unit 31.

[0005] Figure 4 is a conventional block diagram of a bi-directional communication line with the one child device 4 which represents the master unit 3 in FIG. 3, base unit 3 is the same as FIG. 3, handset 4 Specific examples are shown. 41 in the slave unit 4 is a wireless unit, 42 is an O / E converter,
43 is an E / O converter and 46 is a variable gain amplifier. The antenna connected to the duplexer is a shared antenna for transmitting and receiving to and from a portable device moving in the zone. Variable gain amplifier 46
Is configured such that a specified transmission RF output can be obtained by adjusting a difference in line gain due to a difference in length of the optical cable 5 when the slave unit 4 is installed.

[0006]

In a long area such as in a tunnel, a plurality of slave units 4 in the above conventional system are sequentially arranged in a zone 6 from a position close to the master unit 3.
Are scattered so as to be linked to each other, and in the case of a large area such as an underground mall, they are scattered and arranged in a vertical and horizontal lattice. In each case, the lengths of the plurality of optical cables 5 connecting the master unit 3 and each of the plurality of slave units 4 are different from each other, and the length of the plurality of optical cables 5 is one to several meters from the slave unit arranged in the vicinity, and is arranged at the farthest position The slave unit may be as long as 20 km. As described above, the optical cable is characterized by a low loss.
Since there is a loss of 0.5 dB / km, the difference in the loss of the optical cable depending on the position of the slave unit is 0 to 10 dB for installing such a relay device 2, and the electrical signal has a difference of 0 to 2 times the optical loss. A difference of 20 dB occurs.

[0007] As described above, the output RF signal level transmitted from the antenna of the slave unit 4 may not be a problem even if the output level is slightly different in a system such as CATV in which a reproduced image is obtained by an image receiver directly connected to the antenna terminal. This does not occur, but in a mobile phone system that sends out radio waves with an antenna,
The range of radio waves differs and the size of the zone differs for each slave unit, which causes a problem. Therefore, the gain of the variable gain amplifier 46 is adjusted so that the difference in the loss of the optical cable when the slave unit is installed is corrected so that the transmission levels from the antennas are substantially equal so that the areas of the zones of the slave units are substantially equal. The installer is manually adjusting the installation. Therefore, there is a disadvantage that the installation work takes time.

Next, the RF due to the difference in the length of the optical cable 5
The difference between the transmission signal levels will be described. FIG. 5 shows an input RF when a light emitting diode is used as the E / O converter 32.
FIG. 5 is a diagram illustrating an example of direct light intensity modulation characteristics showing a light modulation output with respect to a signal, and is a diagram illustrating a relationship between a current of a light emitting diode and a light output level. This indicates that when a high frequency signal (input RF signal) is superimposed on the bias current of the light emitting diode and driven, an analog intensity modulated optical output is obtained. When the modulation degree of the input RF signal is m, the optical output is A (1+
msin pt) cos ωt, and the converted dB when this output is demodulated is 2 × 10 log A + 20 logm [dB]. 10 log A [dB] of the first term of this equation is a light level.

[0009] Figure 6 is a direct detection operation explanatory diagram of a photodiode, a demodulation (detection) operation explanatory diagram when using the photodiode to the O / E converter 46 of FIG. When light having an optical input level A is input from the optical cable 5 to the photodiode, B flows as a current of the photodiode. Therefore, when the optical input A is intensity-modulated by the RF signal a, the RF signal b is superimposed on the photodiode current B and output. That is, when the optical input is at the A level and the modulation degree of the RF signal a is m, the detected output RF current is b.

However, when the length of the optical cable 5 is long and the loss increases and the optical input level A is A ', the modulation m is constant and the current of the photodiode decreases to B', and the detected output RF The current becomes b 'and similarly decreases. The variable gain amplifier 46 needs to correct an amount by which the output RF signal b is reduced to b ′, that is, an increase in electric signal loss corresponding to twice the loss amount of the optical cable at which the optical input level A becomes A ′. In the above, the downlink from the parent device 3 to the child device 4 has been described, but the uplink has the same disadvantage.

As described above, the variable gain amplifier 46 must be manually adjusted when a new repeater device using conventional optical analog transmission is installed or the slave unit 4 is added. Measurement and adjustment, which requires labor and time.

It is an object of the present invention to provide a bidirectional communication system such as a portable telephone system in which the length of an optical cable due to the installation position when a plurality of slave units of the above-described conventional relay device using optical analog transmission are distributed is arranged. Uses an optical cable that automatically corrects for differences in received light levels due to differences, instead of manually adjusting it, significantly reducing the labor and time required for installation adjustments, and making the zones of each slave unit almost equal. It is an object of the present invention to provide a relay device that has been implemented.

[0013]

Relay apparatus according to claim 1 of the present invention In order to achieve the above object, according to the optical intensity modulation signal converted into light of a high-frequency electrical signals downlink received from the non-linear base station from a plurality of output terminals After distributing and outputting, a plurality of uplink light intensity modulated signals input from a plurality of input terminals corresponding to the plurality of output terminals are respectively detected by a first optical / electrical converter and converted into high-frequency electric signals. A master unit that combines and transmits a transmission wave to the wireless base station, a downlink optical cable connected to each of the plurality of output terminals, and an uplink optical cable connected to each of the plurality of input terminals, A plurality of pairs of optical cables arranged in pairs, and a light intensity received via the downlink optical cable which is connected and distributed to each of the plurality of pairs of optical cables. A transmission wave obtained by detecting the modulation signal by the second optical / electrical converter and converting it into a high-frequency electric signal is transmitted to the portable device, and a light intensity modulation signal obtained by converting the high-frequency electric signal received from the portable device into light. And a plurality of slave units for outputting the signals to the uplink optical cable, wherein the master unit includes a plurality of variable gain amplifiers for respectively amplifying the output signal of the first optical / electrical converter, and the combined high frequency A first monitoring data modulator / demodulator for extracting control data added to monitoring data included in the electric signal, and a first providing a control signal for changing a gain to the corresponding variable gain amplifier according to the control data. Wherein each of the plurality of slave units includes a second current detector for detecting a current value of the second optical / electrical converter, and an output of the second optical / electrical converter. Signal And a control signal for changing the gain so that the difference obtained by comparing the detected value obtained from the second current detector with a preset reference value and reducing the difference to zero is provided to the variable gain amplifier. A second control circuit for extracting the control signal from the second control circuit, adding the control data including the slave unit number and the correction value to the monitor data, and superimposing the control data on a transmission wave; A modem, and each of the transmission waves transmitted from the plurality of slave units regardless of the length of a plurality of pairs of optical cables connected between the master unit and the plurality of slave units. It is characterized in that the level is configured to be substantially constant. Further, the length of the plurality of pairs of optical cables is in a range of 1 m to 20 km.

[0014]

1 and 2 are block diagrams showing a first embodiment of the present invention. The same parts as those in FIG. 3 are denoted by the same reference numerals. The difference from the conventional configuration is that the light receiving detection circuit portions of both the master unit 3 and the slave unit 4 have means for detecting the optical input level from the optical cable 5 and that the RF signal level detected by the detection level is substantially constant. That is, means for performing correction control is provided.

First, in the base unit 3, O / E converters 34-1 to 34-34 such as photodiodes for detecting upstream light transmitted from each of the slave units 4 via the optical cable 5 are provided.
current detector (I-DET) 35- for detecting the current value of n
O / E converters 34-1 to 34-n are provided.
And a variable gain amplifier 36-1 between the
To 36-n.

Next, in the slave unit 4 shown in FIG. 2, the current value of the O / E converter 42 such as a photodiode for detecting the downlink light transmitted from the master unit 3 via the optical cable 5 is determined by the current. The detector (I-DET) 44 detects the loss, the control circuit 45 estimates the loss of the optical cable from the DC current value when the length of the optical cable is 0 m, and the variable gain amplifier 46 similarly to the master station. Is performed for gain control. The variable gain amplifiers 36-1 to 36-n and 46 may be variable attenuators, or may have a configuration in which an amplifier and a variable attenuator are combined. When photodiodes are used as the O / E converters 34 and 42, as shown in FIG. 6 , the current flowing through the photodiode changes linearly with the change in the optical input level. That is, the current detectors 45 and 35 detect the DC current values of the O / E converters 42 and 34 corresponding to the levels of the input light received from the master unit 3 or the slave unit 4 of the relay device 2 via the optical cable 5. .

In the slave unit 4 shown in FIG. 2, reference numeral 47 denotes a monitor data modulator / demodulator, which modulates the gain control data output from the control circuit 45 together with other monitor data and inputs the modulated control data to an amplifier 48 for transmission to the master unit. E in addition to the signal (up signal)
/ O converter 43.

In the master unit 3 shown in FIG. 1 , reference numeral 38 denotes a monitor data modulator / demodulator which demodulates monitor data and control data obtained from the synthesizer 40, and transmits control data consisting of slave unit numbers and cable loss data to a control circuit. Input to 39. The control circuit 39 controls the variable gain amplifiers 36-1 to 36-3 of the corresponding slave unit.
6-n gain. In this case, the control data from each slave unit is sequentially processed by a command (polling) from the master unit 3, so that control signals do not collide.

The reason why the gain of the upstream signal amplifier 48 of each slave unit is not made variable is that the operation of the laser diode used for the E / O converter 43 is set to an optimum state. That is, as the input level of the E / O converter 43 increases, the C / N improves but the IM (intermodulation distortion) deteriorates,
When the input level is lowered, the IM is good but the C / N deteriorates, so that the input level of the E / O converter 43 is always set to the optimum value.

[0020]

As described above in detail, by implementing the present invention, the output R output from the antennas of a plurality of slave units distributed over the optical cables 5 of different lengths is obtained.
The level of the F signal and the transmission level from the master unit to the base station can all be automatically made substantially equal. Therefore, it is necessary to set the variable gain range of the variable gain amplifier based on the distance from the installation point of the master unit to the installation point of the remote unit farthest from the size of the blind spot where the relay device is installed, the planar shape, and the like. Therefore, the labor and time required for installation adjustment for new installation or expansion can be greatly reduced, and the practical effect is extremely large.

[Brief description of the drawings]

1 is a block diagram showing a main device of the actual施例of the present invention.

2 is a block diagram showing a slave unit of the real施例of the present invention.

FIG. 3 is a diagram illustrating an example of a system configuration to which the present invention is applied.

FIG. 4 is a configuration example diagram of a conventional device.

FIG. 5 is a graph showing an example of electrical / optical conversion (direct modulation) characteristics.

FIG. 6 is a diagram illustrating an example of optical / electrical conversion (direct detection) characteristics and the operation of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 wireless base station 2 relay device 3 master unit 4 slave unit 5 optical cable 6 zone 31 wireless unit 32 E / O converter 33 distributor 34 O / E converter 36 variable gain amplifier 38 monitoring data modem 39 control circuit 40 synthesizer 41 Radio Unit 42 O / E Converter 43 E / O Converter 44 Current Detector 45 Control Circuit 46 Variable Gain Amplifier 47 Monitoring Data Modem 48 Amplifier

Continued on the front page (72) Inventor Hiroshi Suzuki 3-14-20 Higashinakano, Nakano-ku, Tokyo International Electric Company (72) Inventor Takashi Yokote 3-14-20 Higashinakano, Nakano-ku, Tokyo International Electric Stock Inside the company (72) Inventor Tadashi Akiyama 3-14-20 Higashinakano, Nakano-ku, Tokyo International Electric Co., Ltd. (72) Inventor Jun Junuma 2- 10-1, Toranomon 2-chome, Minato-ku, Tokyo NTTI (56) References JP-A-4-269023 (JP, A) JP-A-4-157820 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14/00-14/08

Claims (2)

(57) [Claims] An optical intensity modulation signal obtained by converting a downlink high-frequency electric signal received from a radio base station into light is output from a plurality of output terminals and output from a plurality of input terminals corresponding to the plurality of output terminals. A master unit for detecting a plurality of input optical intensity modulated signals of the uplink by a first optical / electrical converter, converting the detected signals into high-frequency electric signals, and combining and transmitting a transmission wave to the radio base station; A plurality of pairs of optical cables in which a downlink optical cable connected to each of the plurality of output terminals and an uplink optical cable connected to each of the plurality of input terminals are arranged in pairs; and A second optical / electrical converter detects a light intensity modulated signal which is connected to each of the optical cables and distributed and is received through the down-link optical cable. A transmission wave into an electric signal sends out to the portable device, is composed of light intensity modulated signal converted into light of a high-frequency electric signal received from the portable device and a plurality of slave unit to be output to the uplink optical cable The master unit includes: a plurality of variable gain amplifiers each amplifying an output signal of the first optical-to-electrical converter; and control data added to monitoring data included in the synthesized high-frequency electrical signal. A first monitoring data modem to extract;
A first control circuit for providing a control signal for changing a gain to the corresponding variable gain amplifier according to the control data, wherein each of the plurality of slave units includes a current of the second optical / electrical converter. A second current detector for detecting a value, a variable gain amplifier for amplifying an output signal of the second optical / electrical converter, and a detection value obtained from the second current detector as a predetermined reference. A second control signal is supplied to the variable gain amplifier to provide a control signal for changing the gain so that the difference becomes 0 with respect to the value.
And a second monitoring data modem for extracting the control signal from the second control circuit, adding the control data including the slave unit number and the correction value to monitoring data and superimposing the control data on a transmission wave. And transmitting from the plurality of slave units regardless of the length of a plurality of pairs of optical cables connected between the master unit and the plurality of slave units.
Relay device each level of the transmission wave issued utilizing optical cables, characterized in that it is configured to be substantially constant level. 2. The length of the plurality of pairs of optical cables is 1 m or more.
20km relay apparatus according to claim 1, wherein a is any one of a range of.