JPH05218921A - Mobile communication relay system - Google Patents

Abstract

(57) [Summary] [Purpose] To ensure good communication between the mobile communication device inside the structure and the outside of the structure. [Structure] An antenna 208 is provided in each area in the tunnel.
A to C and couplers 213A to C are installed. Each of the couplers 213A to 213C is connected to the transmission line C, and the transmission line C
Is connected to the converter 211 at the exit of the tunnel. The converter 211 is provided with an antenna 212, which outputs a transmission wave (frequency f _R1 ) to an exchange or a relay station (not shown),
Also, it receives a signal radio wave (having a frequency of f _R2 ) from the exchange or the relay station. A transmission line L _i is installed, and from the local fundamental wave output terminal of the converter 211 to each of the couplers 213A to 213C.
The local fundamental wave (frequency f _L1 ) is supplied to.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relay system for public mobile communication, and relates to a mobile communication terminal in a structure such as a tunnel or an underground mall where space propagation of radio waves is structurally restricted and an exchange station outside the structure. It is suitable for ensuring a good communication state between.

[0002]

2. Description of the Related Art Modern tunnels have been constructed in the underground to lay wires and cables for communication with remote places, and some tunnels have to be built when roads pass through mountains to facilitate transportation. At, the existence of tunnels is very large. As a result, people are usually operating in the tunnel, such as people passing through the tunnel or working in the tunnel for maintenance.

When traveling in a tunnel or working inside, it is often necessary to communicate between people who are remote from each other. In such a case, as shown in FIG. 7A, a fixed communication device (fixed telephone 1211 or the like) is placed at an appropriate place in the tunnel 200, and a branch cable 1212, a communication cable 1213, and a branch device 1 are provided.
There is a method of connecting 214, an exchange 1215, etc. to make a call between communication terminal devices. With this method, it takes time to reach the communication device unless the number of communication device terminals is very large, and there is almost no practical merit. There is no promise that the other party will be in the proper terminal position, and the possibility of a successful call is extremely low. Since the position of people is not fixed and unfixed, it is very inconvenient to use the fixed communication device between specific places. On the other hand, FIG. 7 (b) shows a case where a fixed communication terminal such as a cordless phone 1216 is used to allow a slight movement, but the movable range is extremely narrow and the above-mentioned drawbacks cannot be solved.

[0004] Here, if it is possible to communicate with each other using a simple mobile communication device such as a transceiver, it is very useful in practice, and communication can be carried out very conveniently.
However, as we often experience, if we try to communicate using a transceiver in a tunnel, we can manage to talk if they are in a direct view of each other, but the tunnel turns around and the other party can't be seen immediately. I can't talk.

Therefore, various methods have been considered. For example, as shown in FIG.
One antenna wire 1311 along the inner wall in the length direction
The antenna wire 1 at any position inside the tunnel 200.
There is a method of performing communication between the transceivers 201A and 201B via 311. However, according to this method, the attenuation along the antenna line 1311 is large, and communication cannot be practically performed. Therefore, by improving this, as shown in FIG. 8B, for example, from the management center 1314 to the antenna line 13
There is one that broadcasts by putting information on 11 and receiving by the receiver 201C. With this method, a large amount of power can be supplied to the antenna line from the management center, so there is a practical example at a frequency of several megahertz or less.

Further, as shown in FIG. 9 (a), there is a method of using LCX which is put into practical use in telephone communication of Shinkansen. In the LCX, an appropriate hole is provided in the outer conductor of the coaxial cable, and when a radio wave is passed through the hole, a part of it leaks to the outside to generate a leakage electromagnetic field in the vicinity thereof. As a result, communication is performed between the communication device 1512 of the electric train 1501 and the relay device 1513 via the LCX 1511.

[0007]

In the method of arranging the antenna wire 1311 shown in FIG. 8 (b), it is only performed in one direction from the management center to the person in the tunnel. Since communication requires a very large amount of power, the size of the communication device becomes large, which greatly impairs portability. Practically, it is impossible for humans to communicate with each other in the tunnel.
In addition, in the method using the LCX shown in FIG.
A frequency of about 80 to 2000 MHz is used due to the technical restriction of CX, and the output of the communication device is set to a large value of about 200 W due to the large loss of the cable to secure the communication quality. As shown in FIG. 9A, when this is used for communication between mobile persons (between the transceivers 201A and 201B), the LCX and the communication device (transceiver 201A) are further used.
A, 201B, etc.) is added, so that FIG.
The same problem as the method of arranging the antenna wire 1311 shown in (a) and (b) arises, and it is practically impossible for humans to communicate with each other in the tunnel. Meanwhile, car phones, mobile phones,
The spread of public mobile communication such as pagers is remarkable, and there is an increasing demand for using it in tunnels. Unfortunately, I haven't found a way to satisfy this yet.

The present invention proposes a method capable of performing high-quality communication in the tunnel by using the above-mentioned public mobile communication device.
The method of the present invention is not limited to wireless communication within a tunnel but has a wide range of applications.

[0009]

In order to solve the above problems, the mobile communication relay system of the present invention is designed to move within a structure (for example, a tunnel, an underground mall, or an electromagnetically shielded building). A mobile communication relay system for relaying communication between a communication terminal (automobile phone, mobile phone, pager, etc.) and a mobile communication terminal exchange station or relay station provided outside a structure. An antenna for transmitting and receiving radio waves having mutually different frequencies to and from a communication terminal, and a first frequency conversion means for frequency-converting a reception signal from the antenna and outputting it as a first intermediate frequency signal to a transmission line,
A first frequency conversion means for inputting a second intermediate frequency signal, converting the frequency, and outputting the frequency to the antenna, and an antenna-transmission line coupler provided for each antenna and connected to the transmission line, and an exchange station. Alternatively, the received wave output from the relay station is received, frequency-converted, and output as a second intermediate frequency signal to the antenna-transmission line coupler via the transmission line to output the first intermediate frequency signal from the transmission line. An antenna-transmission line converter for frequency-converting and outputting as a transmission wave to a switching station or a relay station is provided.

Here, the antenna-transmission line coupler comprises a reception signal detecting means for detecting the level of a reception signal from the antenna, and a first signal when the level detected by the reception signal detecting means is below a predetermined level. It may be configured to further include a switch means for turning off the output of the intermediate frequency signal.

[0011]

In the mobile communication relay system of the present invention, an antenna and an antenna-transmission line coupler are provided in the structure, and these connect the first intermediate frequency signal and the second intermediate frequency signal to the transmission line. Via the antenna-transmission line coupler. The antenna-transmission line coupler and the exchange exchange the transmitted and received waves with each other. Therefore, it is possible to communicate between the mobile communication terminal and the exchange in each area where the antenna and the antenna-transmission line coupler are provided in the structure via the mobile communication relay system.

When the antenna-transmission line coupler is improved by the reception signal detecting means and the switching means, when there is no reception signal from the antenna, that is, when the mobile communication terminal is not used, the antenna-transmission line coupler is Since the output to the transmission line is turned off, noise is not output from the antenna-transmission line coupler to the transmission line, and the transmission line C / N
Is improved.

[0013]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the basic configuration of a mobile communication relay system of the present invention.

The inside of the tunnel is appropriately divided, and antennas 208A to 208C and antenna transmission line couplers (hereinafter simply referred to as couplers) 213A to 213C are installed in respective areas. There is. Each coupler 213
A to C are connected to a signal transmission line (hereinafter referred to as transmission line) C, and the transmission line C is connected to an antenna-to-transmission line converter (hereinafter referred to as converter) 211 at the exit of the tunnel. The converter 211 includes an antenna (the antenna and the antenna have the same meaning, but in the text, the antenna installed inside the tunnel is used as an antenna, and the antenna emitting or receiving radio waves outside the tunnel as an antenna). 212 is provided to output a transmission wave (frequency f _R1 ) to a switching station or a relay station (not shown) and receive a signal radio wave (frequency f _R2 ) from the switching station or the relay station. A transmission line (hereinafter, transmission line) L _i for transmitting a local oscillator signal is installed, and the converter 211
The local fundamental wave (frequency f _L1 ) is supplied to each of the couplers 213A to 213C from the local fundamental wave output terminal.

Antennas 208A-C are located within the area.
Mobile communication terminal 214 and radio waves (frequency f _R1, Frequency f_R2)
It is used for sending and receiving, and it is a loading type as shown in Fig. 2.
It is preferable to use a two-wire type
An antenna in a tunnel can also be used. These are the bonds
213A to 213C are connected at the feeding point 101.

FIG. 4 shows the structure of the converter 211. In this figure, amplifiers AMP1 and AMP5 are A
It is a GC amplifier, and if the input level is within a predetermined design range, the output has a constant value. The coupling circuit CP is a coupling circuit of a line and a coupler, and when viewed from the transmission line side, many couplers can be connected with almost no load, and the output from the coupler to the transmission line is designed as a level. It is designed so that the appropriate value is obtained. In FIG. 5, the coupler 21
3A-C configurations are shown. In this figure, amplifiers AMP3 and AMP7 are AGC amplifiers.

The details of the functional operation of the present proposal will be described below.

Since this system enables public mobile communication inside and outside a tunnel, all communication control such as exchange of telephone calls is performed on the mobile radio exchange side (not shown). That is, communication is performed via the exchange. Therefore, the function from the mobile communication terminal 214 in the tunnel to the switching center and the function of the route from the switching center to the mobile communication terminal in the tunnel will be described separately.

In FIG. 1, a radio wave (frequency f _R1 ) transmitted from a mobile communication terminal 214 in a tunnel is received by an antenna 208B arranged in an area (area) in which the mobile communication terminal 214 exists and connected to it. Splicer 21
Input to 3B. In FIG. 5, the radio wave (frequency f _R1 ) input to the coupler 213B is input to the demultiplexer BF1 from the antenna terminal A1 and is frequency-selected to demultiplexer BF.
The signal is output from the R1 terminal of No. 1 and further AGC-amplified by the amplifier AMP1 to have a constant level.

Next, the mixer X1 mixes with the local output having the frequency f _L1 and frequency-decreases (Doun Convert), and the frequency is a low frequency (f _i1 = f ₁₎ suitable for transmission through the transmission line C.
_R1- f _L1 ) intermediate frequency signal. Here, the local oscillator output (frequency f _L1 ) is a local fundamental wave having a frequency f _Li sent from the converter 211 through the transmission line Li and is n.
It is made by multiplying by ₁ (f _L1 = f _Li × n ₁ ). Frequency f _i1
The intermediate frequency signal of 1 is amplified again, passes through the demultiplexer BF2, further passes through the coupling circuit CP, and is output from the transmission line terminal T1 to the transmission line C.

The intermediate frequency signal of frequency f _i1 output to the transmission line C is input to the converter 211 via the transmission line C in FIG. In FIG. 4, the converter 211
Of the transmission line terminal T2. The intermediate frequency signal (frequency f _i1 ) passing through the transmission line terminal T2 is selected by the demultiplexer at BF3 and output to the terminal I1. Then, AGC amplification is performed by the amplifier AMP5. Converter 211 and combiner 213
Since the distance between B greatly changes depending on the area where the coupler 213B exists, the level of the signal reaching the converter 211 changes greatly due to the difference in the amount of attenuation due to the difference in the length of the transmission line. However, the AGC of the amplifier AMP5
The output level is constant due to the amplification.

Next, the mixer X3 mixes it with the local oscillation output having the frequency f _L1 and up-converts the frequency.
Since the local oscillator output (frequency f _L1 ) is generated by multiplying the local oscillator fundamental frequency (frequency f _LI ) distributed to each coupler 213A to C by n ₁ times, this is the station of each coupler 213A to C. It is equal to the emission frequency f _L1 . Therefore, the frequency of the frequency-multiplied signal is restored to the frequency f _R1 of the radio wave radiated from the mobile communication terminal 214 by the calculation “f _i1 + f _L1 = f _R1 −f _L1 + f _L1 = f _R1 ”.

After that, the signal wave from the mixer X3 is amplified to a predetermined level by the amplifier AMP6, passes through the demultiplexer BF4, and is output from the terminal A2. In FIG. 1, a transmission wave (frequency f _R1 ) is fed from a converter 211 to an antenna 212 and is radiated toward an exchange (not shown).

Next, communication from the exchange to the mobile communication terminal 214 will be considered. In FIG. 1, a signal radio wave (having a frequency f _R2 ) from a relay station (or a switching _center ) is received by an antenna 212 and input to a converter 211. 4, the signal wave input to the transducer 211 (frequency f _R2) will enter the terminal A2 to the transducer, is selected by the demultiplexer BF4 output by terminal R _4, is the AGC amplifier by an amplifier AMP7. The intensity of the radio wave reaching the antenna 212 from the relay station fluctuates due to fading.
The output is kept at a stable level by the AGC amplification of MP7.

The output of the amplifier AMP7 is a frequency f _L2 (= f _Li2 ×) created by multiplying the local oscillation fundamental frequency f _Li by n _2.
n) is mixed with the local oscillation output by the mixer X4 and converted into an intermediate frequency signal of low frequency f _i2 (= f _R2 −f _L2 ) which can be transmitted through the transmission line. After that, it is amplified to an appropriate level by the amplifier AMP8, and is output to the transmission line C from the transmission line terminal T ₂ via the branching filter BF3. In this case, the transmission line C is frequency-multiplexed with two intermediate frequency signals of frequency f _i1 and frequency f _i2 .

In FIG. 1, the intermediate frequency signal (frequency f _i1 ) output from the converter 211 to the transmission line C is transmitted to the couplers 213A to 213C. 5, in each of the couplers 213A to 213C, the signal is output from the transmission line terminal T1 to the demultiplexer BF2 via the coupling circuit CP. Next, the frequency is selected by the demultiplexer BF2, AGC amplified by the amplifier AMP3, and adjusted to a constant level. After that, the mixer X2 mixes it with the local output of the frequency f _L2 to up-convert the frequency. Local output (frequency f _L2 )
Is generated by multiplying the local fundamental wave (frequency f _Li ) sent from the converter 211 by the transmission line Li by n ₂ .
Therefore, in the same manner as the case of the route to the relay station from the mobile communication terminal 214, the frequency f _L2 of the local oscillation output produced by the combiner 213A~C includes a frequency f _L2 of the local oscillation output produced by transducer 211 It is a perfect match. Therefore, the frequency of the frequency-multiplied signal is "f _i2 + f _L2 = f _R2 -f _L2 + f
The operation of _L2 = f _R2 ', consistent with the original frequency f _R2 that has been transmitted from the relay station. That is, the signal has now been returned to the frequency from the relay station. Of course, the radio wave format is completely preserved.

The signal from the mixer X2 is supplied to the amplifier A
After being amplified to a proper level by MP4, the duplexer BF
The signal is output from the terminal A1 to the antennas 208A to 208C via the terminal 1. In FIG. 1, power is supplied to the antennas 208A to 208C from the couplers 213A to 213C and is radiated into the tunnel 200. The radiation from the antennas 208A to 208C is performed from all the antennas 208A to 208C laid in the tunnel. Therefore, no matter where the mobile communication terminal 214 is in the tunnel, signal radio waves from the antennas 208A to 208C (frequency f _R2 ) reaches the mobile communication terminal 214.

In this way, in the route from the exchange to the mobile communication terminal 214 as well, as in the case of the mobile communication terminal 214 to the exchange, communication is performed without changing the radio wave format including the frequency. ..

Looking at the path from the mobile radio terminal 214 to the exchange and its function, the radio waves leaving the antenna 212 retain the same form as the radio waves emitted from the mobile terminal including the frequency. The radiated power of the antenna 212 is only adjusted to a level at which communication is possible. Also,
Focusing only on the conversion station and the mobile communication terminal 214, conventionally,
When the mobile communication terminal 214 entered the tunnel, the radio waves became invisible to each other and the communication became impossible. However, according to the present proposal, the radio wave from the mobile communication terminal 214 is transmitted by any of the antennas 208A to 208C in the tunnel. When the mobile communication terminal 214 receives or receives the radio wave from any of the antennas 208A to 208C, the mobile communication terminal 214 can communicate with each other by being visible to each other. From the viewpoint of the exchange, the mobile communication terminal 214 only looks as if it exists at the position of the antenna 212 of the present system, so the communication control at this time is performed in exactly the same way as before.

It is possible to improve the communication quality by improving the C / N of the signal from the antenna 212 to the switching center by improving the above embodiment. This is accomplished by improving the combiner and will explain this point.

The coupler shown in FIG. 6 is characterized in that a switch S1 and a level determination circuit D1 are provided at the output of the amplifier AMP2, as compared with the coupler shown in FIG.
The level determination circuit D1 is set to turn on the switch S1 when the output of the amplifier AMP2 becomes larger than a predetermined level. The operation of the coupler of FIG. 6 is as follows.

When there is no call from the mobile communication terminal 214, since no radio wave is output from the mobile communication terminal 214, no signal is input from the terminal A1. At this time, the switch S1 is in the off state, and noise generated in the amplifier AMP1, mixer X1, and amplifier AMP2 is blocked by the switch S1 and is not output to the transmission line C. When there is a call from the mobile communication terminal 214,
The output of the amplifier AMP2 becomes larger than the level set by the level determination circuit D1, and this is the level determination circuit D1.
Detected in. The level determination circuit D1 outputs the output v _L ,
As a result, the switch S1 is turned on and the amplifier AMP is turned on.
The output of 2 is output to the transmission line C. The operation of the coupler shown in FIG. 6 is the same as that shown in FIG.
It is added that when there is a call from 14, the output (intermediate frequency signal) is output to the transmission line C, and when there is no call, the output is turned off.

The coupler of FIG. 6 is replaced with the coupler 213A of FIG.
When used for C to C, only the coupler 213B that receives the radio wave from the mobile communication terminal 214 receives the intermediate frequency signal (frequency f
_i1 ) is output to the transmission line C, and noise of the couplers 213A and 213C is blocked by the switch S1 and is not output to the transmission line C. Therefore, the C / N of the intermediate frequency signal (frequency f _i1 ) is improved on the transmission line C, and the antenna 212
C / N of the signal from the mobile station to the exchange is improved. In particular, it is effective when a large number of couplers are connected in a large-scale tunnel. In this case, although there are many couplers that do not receive the radio waves from the mobile communication terminal 214, noise from these couplers can be suppressed and the deterioration of C / N can be suppressed to maintain good communication quality.

As is apparent from the above, according to the relay system for mobile communication of the present invention, the mobile communication terminal 21
In the normal case where 4 exists in the tunnel and radio waves do not reach, communication can be performed in the same manner as when the terminal exists outside the tunnel even when communication becomes impossible. In addition, this mobile communication relay system has no changes to important elements such as the type of radio waves, and has not touched the type at all, so it does not adversely affect system performance and is widely applied to public mobile communications. It can be done.
Although this embodiment has been focused on the communication inside and outside the tunnel, it should be understood that the present proposal can be generally applied to places where radio waves do not reach, such as underground of a building.

Further, in the embodiment, the intermediate frequency signal whose frequency is reduced is used. This is a frequency for public mobile radio (frequency f _R1 , f _R2 of transmitted / received waves of the mobile communication terminal 214).
Is assigned to a very high frequency band such as 800 MH _Z band, so that it usually has a large loss for transmission on a transmission line, and it may be necessary to insert a relay amplifier in the middle. It is complicated and uneconomical. Therefore, although the frequency is converted to the frequency f _i1 with a small transmission loss to simplify the transmission line system, an intermediate frequency signal whose frequency is increased can be used depending on the frequency band used.

Further, although the same transmission line is used for the two intermediate frequency signals of the frequency f _i1 and the frequency f _i2 , it is also possible to use different transmission lines, and it is technically almost the same. When it is dedicated, the number of electric signals transmitted for one system decreases depending on the condition, so that C / N may improve. Since the structure of the transmission line is simplified when the transmission line is shared, this need can be evaluated and decided from the economical point of view.

Although the transmission line C for transmitting the two intermediate frequency signals and the transmission line Li for transmitting the basic station oscillation frequency have been described as separate items, they are frequency-multiplexed to form a transmission line. It should be obvious that can be summarized in one article.

[0038]

As described above, according to the mobile communication relay system of the present invention, even in a structure such as a tunnel or an underground mall where the spatial propagation of radio waves is constrained, each area in the structure is exchanged with the outside. Since it is possible to communicate with the central office via this mobile communication relay system, it is possible to secure a good communication state between the mobile communication terminal in the structure and the exchange, and to the communication terminal outside the structure. Telephone communication is possible.

When the antenna-transmission line coupler is improved by the received signal detecting means and the switching means, the transmission line C /
N is improved, and higher quality communication becomes possible.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a mobile communication relay system of the present invention.

FIG. 2 is a configuration diagram of a loading antenna.

FIG. 3 is a configuration diagram of an antenna using a reciprocating line.

FIG. 4 is a configuration diagram of an antenna-transmission line coupler.

FIG. 5 is a configuration diagram of an antenna-transmission line coupler.

FIG. 6 is a configuration diagram of an improved example of an antenna-transmission line coupler.

FIG. 7 is an explanatory diagram of a system using a fixed communication device.

FIG. 8 is an explanatory diagram of a conventional communication method.

FIG. 9 is an explanatory diagram of a method using LCX.

[Explanation of symbols]

200 ... Tunnel, 208A-C ... Antenna, 211 ...
Antenna-to-transmission line converter, 213A to 213C ... Antenna-transmission line coupler, 214 ... Mobile communication terminal, C ... Transmission line, X1 to X4 ... Mixer, S1 ... Switch, D1 ... Level determination circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Ryuzu 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor, Yoshizo Shibano 1-chome, Shimaya, Osaka, Osaka No. 3 Sumitomo Electric Industries, Ltd. within Osaka Works (72) Inventor Seiichi Higuchi 1-3-1 Shimaya, Konohana-ku, Osaka City, Osaka Prefecture Sumitomo Electric Industries, Ltd. (72) Inventor Toraichi Murakami Chiyoda, Tokyo 1-6 No. 1 Saicho-cho in the ward Nihon Telegraph and Telephone Corporation (72) Inventor Yasunori Mukai 1-1-6 Uchiyuki-cho Chichida-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Takayuki Shimabara Chiyoda Tokyo 1-6-6 Sachimachi, Uchi-ku Nihon Telegraph and Telephone Corporation (72) Inventor Yukio Togo 7-631 Omori Nishi, Ota-ku, Tokyo Sumiden Opcom Co., Ltd.

Claims (2)

[Claims] 1. A mobile communication relay system for relaying communication between a mobile communication terminal inside a structure and a switching center or a relay station of the mobile communication terminal provided outside the structure, An antenna for transmitting and receiving radio waves having different frequencies to and from the mobile communication terminal; and a first frequency conversion means for frequency-converting a reception signal from the antenna and outputting it as a first intermediate frequency signal to a transmission line. A first frequency conversion means for inputting a second intermediate frequency signal, converting the frequency, and outputting the frequency to the antenna, and an antenna-transmission line coupler provided for each antenna, and connected to the transmission line. The received wave output from the exchange station or the relay station is received, frequency-converted, and output as a second intermediate frequency signal to the antenna-transmission line coupler via the transmission line to transmit the transmission signal. A relay system for mobile communication, comprising: an antenna-transmission line converter that frequency-converts a first intermediate frequency signal from a transmission line and outputs it as a transmission wave to the exchange station or the relay station. 2. The antenna-transmission line coupler comprises: a received signal detecting means for detecting a level of a received signal from the antenna; and the level detected by the received signal detecting means is below a predetermined level. 2. The mobile communication relay system according to claim 1, further comprising switch means for turning off the output of the intermediate frequency signal of No. 1.