JPH09200842A - Mobile communication system using manhole antenna - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: Communication of a mobile communication system using a manhole antenna including a manhole antenna configured inside a manhole cover attached to sewer and a mobile communication terminal communicating with the manhole antenna. Improve quality. SOLUTION: A wireless repeater 8 is provided on a traffic signal at an intersection where communication is possible with both the manhole antenna 1 and the mobile communication terminal 4, and the communication between the manhole antenna 1 and the mobile communication terminal 4 is relayed. To do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system using a manhole antenna including a manhole antenna formed inside a manhole cover attached to a sewer and a mobile communication terminal for communicating with the manhole antenna. It is about.

[0002]

2. Description of the Related Art FIG. 26 is a diagram of an information communication system of this type disclosed in Japanese Patent Laid-Open No. 5-227073. In the figure, 1 is a manhole base station. In the manhole base station 1, an antenna (not shown) is provided inside the manhole cover attached to the sewer by a dielectric cover or the like so as to radiate radio waves on the road. This antenna is connected to a radio wave transmitter / receiver (not shown). The radio wave transmitter / receiver is connected to an optical / electrical signal converter (not shown) that converts an electric signal into an optical signal or converts an optical signal into an electric signal. The optical / electrical signal converter is connected to an optical fiber (not shown). As described above, the manhole base station 1 uses the optical fiber cable as an interface to the inside of the sewer. 2 is a building such as a building,
3 is a road such as a roadway or a sidewalk, 4 is a mobile terminal that communicates with the manhole base station 1 via radio waves on the ground, 5 is an optical fiber network buried underground or installed in a sewer or a common ditch, and 6 is an optical fiber An optical fiber repeater provided at a required part of the network 5 is a media center to which information is sent from the manhole base station 1 through the optical fiber network 5.

An information communication system using the manhole base station 1 operates as follows. Manhole base station 1 above
The fiber optic cable from is connected to the fiber optic network 5. The optical fiber network 5 is directly connected to the media center 7 via an optical fiber repeater 6 for repairing an optical signal. The media center 7 has a switching function for connecting a signal from the manhole base station 1 to an ISDN network or the like and realizing communication such as telephone or FAX. With the above configuration,
Realizes an information communication system.

[0004]

Although the conventional information communication system using the manhole base station 1 is configured as described above, the mobile terminal 4 is far from the manhole base station 1, or the shadow of the building. If it is out of line of sight,
There are problems that the communication quality is deteriorated or communication is disabled.

The present invention has been made in order to solve the above-mentioned problems, and includes a mobile terminal 4 and a manhole base station 1.
The purpose is to enable communication even when the line of sight cannot be taken.

[0006]

A mobile communication system using a Marl antenna according to claim 1 is a manhole antenna formed inside a manhole cover attached to a sewer, and mobile communication for communicating with the manhole antenna. In a mobile communication system using a manhole antenna provided with a terminal, for when the manhole antenna and the mobile communication terminal cannot communicate directly with each other, for both the manhole antenna and the mobile communication terminal A repeater installed in a structure on a road at a communicable position is provided, and communication between the manhole antenna and the mobile communication terminal is performed via the repeater.

A capacitor antenna, a dipole antenna, a microstrip antenna or the like is used as the manhole antenna. As the mobile communication terminal, there are a mobile phone, a car phone, a mobile information terminal, and the like. The repeater is provided at, for example, a cross road, a T-shaped road, or a Y-shaped road.

In a mobile communication system using a manhole antenna according to a second aspect of the present invention, the repeater includes a plurality of antennas and performs diversity reception processing for preventing fading based on received signals of the plurality of antennas. .

Diversity reception processing includes space diversity, polarization diversity, angle diversity, frequency diversity and time diversity, and combining processing thereof includes selective combining, equal gain combining, and maximum ratio combining.

In a mobile communication system using a manhole antenna according to a third aspect of the present invention, the repeater has a directional antenna having a main beam in the direction of the manhole antenna and a wide directivity for communicating with the mobile communication terminal. And an antenna having the same.

A mobile communication system using a manhole antenna according to a fourth aspect of the present invention includes a plurality of directional antennas in which a main beam directs a plurality of manhole antennas, and a plurality of signals from the mobile communication terminal are transmitted to the plurality of directional antennas. Which transmits to all of the plurality of manhole antennas via the directional antenna of, and receives the signal from any of the plurality of manhole antennas by the plurality of directional antennas and transmits to the mobile communication terminal. Is. The signals received by the plurality of manhole antennas are appropriately selected by the central processing unit.

In the mobile communication system using the manhole antenna according to the fifth aspect, the radiation pattern of the antenna for the repeater to communicate is a radiation pattern having a main beam along the road.

In a mobile communication system using a manhole antenna according to a sixth aspect of the present invention, the repeater is installed using a traffic signal at an intersection.

In a mobile communication system using a manhole antenna according to a seventh aspect, the manhole antenna is
When the signal is directly received from the mobile communication terminal and the signal of the mobile communication terminal is received via the repeater, either one of the signals having stronger signal strength is selected.

The receiver connected to the manhole antenna includes a signal receiving unit of the mobile communication terminal, a signal receiving unit of the repeater, and a comparing unit for measuring and comparing receiving levels of these receiving units. And a switch that selects the output of the two receiving units under the control of the comparing unit. When the signal from the mobile communication terminal and the signal from the repeater compete with each other, the one with higher reception strength is selected to eliminate the conflict condition.

In the mobile communication system using the manhole antenna according to claim 8, the manhole antenna is
One of the signals that does not cause fading when receiving the signal from the mobile communication terminal directly at the first frequency and receiving the signal of the mobile communication terminal at the second frequency via the repeater. Is the one that is selected.

The receiver connected to the manhole antenna has a signal receiving unit of the mobile communication terminal, a signal receiving unit of the repeater, and whether or not fading occurs in the received signals of these receiving units. The determination unit includes a determination unit and a switch that selects outputs from the two reception units under the control of the determination unit. When the signal from the mobile communication terminal and the signal from the repeater compete with each other, the one without fading is selected to eliminate the conflict condition. Also, the reception state can be improved. The fading mentioned here includes not only a phenomenon in which the received electric field fluctuates with time due to a difference in propagation path of radio waves, but also fluctuation caused by interference or the like.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment of the Invention 1 is a schematic configuration diagram of a communication system according to a first embodiment of the invention. FIG. 1 is a view of the city seen from above. In the figure, 1a and 1b are manhole base stations. In each of the manhole base stations 1a and 1b, an antenna is provided inside the manhole cover attached to the sewer so as to radiate radio waves on the road by a dielectric cover or the like. This antenna is connected to a radio wave transmitter / receiver (not shown). The radio wave transmitter / receiver is connected to an optical / electrical signal converter (not shown) that converts an electric signal into an optical signal or converts an optical signal into an electric signal. The optical / electrical signal converter is connected to an optical fiber cable (not shown). This optical fiber cable is connected to an optical fiber network 5 described later. in this way,
The manhole base station 1 uses an optical fiber cable as an interface to the inside of the sewer.

2 is a building such as a building, 3 is a road such as a roadway or a sidewalk, 4 is a mobile terminal that communicates with the manhole base station 1 on the ground via radio waves, and 5 is buried underground or installed in a sewer or a common ditch. Optical fiber network, 6 is an optical fiber network 5
An optical fiber repeater provided at a required location of the media center 7 is a media center to which information is sent from the manhole base station 1 through the optical fiber network 5.

Reference numeral 8 denotes a wireless repeater, which is provided along a road or above a road intersection, for example, at a traffic light, a street light, a telephone pole, a guide sign, or the like. An antenna 9 is connected to the wireless repeater 8 and is used for communication between the manhole base station 1 and the mobile terminal 4.

Although the type of the antenna is arbitrary, for example,
A monopole antenna, a dipole antenna, etc. can be considered. As basic required performance, it has directivity in the horizontal plane that matches the shape of the service zone, and has high gain,
In order to increase the repeated use of the same frequency geographically, it is difficult for radio waves to reach far away.

FIG. 2A is a sectional view of a capacitor antenna mounted on a manhole. In the figure, 1
Reference numeral 01 is a capacitor antenna, 102 is a dielectric manhole, and 103 is a dielectric cover that covers the capacitor antenna. FIG. 2B is a radiation characteristic diagram of the capacitor antenna of FIG. The pattern in this figure is a conical pattern, which is rotationally symmetric about an axis perpendicular to the manhole 102. As can be seen from FIG. 2B, there is almost no gain above. Moreover, the gain is relatively high at a relatively short distance. Therefore, it is suitable for distant or low elevation angle,
It is suitable as a manhole antenna. The polarization is vertical.

FIG. 3A is a sectional view of a dipole antenna attached to a manhole. In the figure, 1
Reference numeral 04 is a dipole antenna. 3 (b) (c)
FIG. 4 is a radiation characteristic diagram of the dipole antenna of FIG. 3B and 3C show patterns in the azimuth direction AZ and the elevation angle direction EL, respectively. As can be seen from these characteristic diagrams, there is a directional pattern along the road. In this respect, it is often suitable for this communication system. The polarization is horizontal.

FIG. 4A is a sectional view of a microstrip antenna attached to a manhole. In the figure, 105 is a microstrip antenna, and 106 is a ground conductor. FIG. 4B is a radiation characteristic diagram of the microstrip antenna. As can be seen from this figure, this antenna has directivity.

Next, the relationship between the installation position of the manhole base station 1 and the antenna line-of-sight range will be described with reference to FIGS. In the following description, for convenience sake, the upper side will be referred to as north, and roads to the north, roads to the south, roads to the west, and roads to the east will be referred to as RN, RS, RW, and RE, respectively. FIG. 5 (a)
Indicates the line-of-sight range when the manhole base station 1 is placed at a crossroad intersection. At this time, road RN-RS and road R
There are prospects for both E-RW. Although the manhole is often installed at the end of the road, it is drawn in the center of the intersection for convenience of illustration. FIG. 5B shows the manhole base station 1.
Shows the line-of-sight range when the vehicle is placed on the road RN-RS other than the intersection. At this time, the road RN-RS has a prospect, but the road RE-RW has little prospect. However, although it propagates to some extent due to the diffraction of radio waves, it does not propagate very far.

FIG. 6A shows the line-of-sight range when the manhole base station 1 is arranged at a T-junction intersection. At this time, the line-of-sight range is the same as in FIG. FIG. 6B shows the line-of-sight range when the manhole base station 1 is placed on the road RS other than the intersection. At this time, only the road RS is the line-of-sight range.

FIG. 7A shows a line-of-sight range when the manhole base station 1 is arranged at a Y-shaped intersection. At this time, there are prospects for both the road RNW-RS and the road RNE-RS. FIG. 7B shows a line-of-sight range when the manhole base station 1 is arranged on the road RN-RS other than the intersection. At this time, there is a prospect for the road RS, but there is almost no prospect for the road RNW-RS and the road RNE-RS. However, since the road makes a gentle angle, radio waves are likely to be diffracted, and the waves travel a little farther than in the case of a T-shaped road.

5 to 7 correspond to a wireless zone in mobile communication. The feature of the communication system using the manhole base station is that the wireless zone has a shape as shown in these figures. This is because the manhole is located in the city and its installation position is low on the ground surface, so it is easily affected by surrounding buildings. In other mobile communications, wireless zones take other forms. For example, a train radio has a linear zone configuration, and a car phone has a planar zone configuration.

Next, the wireless repeater 8 will be described. FIG.
FIG. 3 is a schematic configuration diagram of a wireless repeater 8. Reference numeral 81 is a transmission / reception switcher including a directional coupler, a circulator, and the like, 8
Reference numeral 2 is a frequency converter that receives a reception signal of the antenna 9 from the transmission / reception switch 81 and performs frequency conversion, and 83 is a frequency converter 8
It is an amplifier that amplifies the output of 2 and outputs it to the transmission / reception switch 81. The wireless repeater 8 uses the antenna 9 for both transmission and reception. The radio wave transmitted from the manhole base station 1 is received by the antenna 9 and becomes an electric signal inside the wireless repeater 8. This electric signal is sent to the frequency converter 82 and the amplifier 83 inside the wireless repeater 8. After a predetermined frequency conversion and amplification process for performing communication between the manhole base station 1 and the mobile terminal 4, the output is sent to the antenna 9 and again transmitted to the road. In this way, the radio signal is restored, amplified, and transmitted to the position of the mobile terminal 4,
The mobile terminal 4 can perform reception with stable intensity.

Next, the operation will be described with reference to FIGS. 9 and 10. For example, consider a case where the carried mobile terminal 4 moves as shown in FIG. In the figure, the mobile terminal 4 moves as follows. (1) Head north on roads RN1-RS1. Road RN1-
Let P be the region of RS1. (2) At the intersection of roads RN1-RS1 and road RW1-RE1, turn east and go straight on road RW1-RE1. This intersection is designated as Q, and the road RW1-RE1 is designated as R. (3) At the intersection of roads RN2-RS2 and roads RW1-RE1, turn south and go straight on roads RN2-RS2. Areas of the road RN2-RS2 from this intersection are designated as S and T.

Area P is a communicable range of only the manhole base station 1a. Area Q is a communicable range of the manhole base station 1a and the wireless repeater 8. Region R is a communicable range of only the wireless repeater 8. Area S is a communicable range of the manhole base station 1b and the wireless repeater 8. Region T is a communicable range of only the manhole base station 1b.

In the area P, the mobile terminal 4 communicates with the manhole base station 1a at the frequency f1 as shown in FIG. 10 (a). At this time, the wireless repeater 8 does not participate at all.
In the area Q, as shown in FIG. 10B, the mobile terminal 4 can communicate with both the manhole base station 1a and the wireless relay 8 at the frequency f1. Either one may be selected for communication with the mobile terminal 4. For example, as long as communication with the manhole base station is maintained, this may be prioritized and the output of the wireless repeater 8 may be ignored, or one of the stronger outputs may be selected. Alternatively, the one that is less affected by fading may be selected.

In the region R, as shown in FIG. 10C, the mobile terminal 4 can communicate only with the wireless repeater 8.
At this time, the mobile terminal communicates with the radio repeater 8 at the frequency f1, and the radio repeater 8 communicates with the manhole base station 1b at the frequency f2.
Communicate with. The reason why the frequency is changed in the wireless repeater 8 in this way is to prevent interference and fading. As a case where interference occurs, the radio wave of the mobile terminal 4 may happen to reach the manhole base station 1b. The frequency does not have to be changed when there is no risk of interference.

In the area S, the mobile terminal 4 can directly communicate with the manhole base station 1b as shown in FIG. 10 (d), or can communicate with the manhole base station 1b via the wireless repeater 8. The manhole base station 1b communicates with the mobile terminal 4 at the frequency f1 and with the wireless repeater 8 at the frequency f2. The manhole base station 1b selects, for example, one having a higher signal strength or one having less fading. Area T
In FIG. 10 (e), the mobile terminal 4 communicates with the manhole base station 1b at the frequency f1. At this time, the wireless repeater 8 does not participate at all.

By the way, in a communication system using manhole base stations, the communicable range of one manhole base station is relatively narrow, and the manholes are scattered everywhere so that a large number of base stations can be provided. Therefore, it is possible to communicate at a low frequency (for example, two frequencies f1 and f2). Generally, in a mobile communication system, an important evaluation measure is how many times the same frequency can be used repeatedly between zones that are far from the requirement regarding the co-channel interference protection ratio. From this viewpoint, the communication system using the manhole base station is considered to be excellent.

Next, the installation conditions of the wireless repeater 8 will be described. The installation conditions are specifically as follows. (1) It is possible to communicate with one manhole base station and not within the communicable range of another manhole base station. This is because if it is possible to communicate with a plurality of manhole base stations at the same time, problems such as interference will occur. (2) One relay station can cover the incommunicable area between the manhole base stations. (3) Desirably, intersections such as crossroads, T-shaped roads, and Y-shaped roads. For example, it may be installed on the traffic light. This example is shown in Figure 1.
1 (a). (4) Even if the road is a straight road and the distance between manhole base stations is wide and an incommunicable area occurs, it may be installed on a road guide plate or a telephone pole. An example of this is shown in FIGS.

Providing the wireless relay 8 above the intersection has the following advantages. Generally, in mobile communication, it is ideal from the standpoint of radio wave propagation characteristics that the base station and the terminal are arranged in an environment in which there is no obstacle between them and they can be seen from each other. However, in mobile communication via the manhole base station, this condition is not always satisfied between the manhole base station and the mobile terminal. Particularly, in the case where the mobile terminal 4b and the manhole base station 1b in the central portion of FIG. 1 are in the shade of a building, the communication quality is significantly deteriorated. Therefore, if a wireless repeater 8 is provided above the intersection, a plurality of roads intersect at the intersection,
In other words, it is a point where multiple roads can be seen, and the wireless repeater 8
Is preferable as a place to provide the service area, and the service area of one manhole base station 1 can be widened.

Further, there are the following advantages. Since the manhole base station 1 is arranged on the road, obstacles on the road such as pedestrians, cars, and guardrails may adversely affect radio wave propagation. If the antenna 9 of the wireless repeater 8 is provided above the intersection, there are fewer obstacles than the position of the manhole base station 1, and the radio wave propagation characteristics are improved.

Therefore, as an application example of the first embodiment of the present invention, not only the communication with the shadow of the building but also the service area where the radio wave propagation condition of the manhole base station 1 is comparatively large and the radio wave propagation situation is not good It is thought that it can be effectively used for communication. In this case, the antenna 9 receives the signal from the manhole base station 1 weakened by the obstacle, and the wireless repeater 8 restores and amplifies the signal, which improves the communication quality. The same applies when the manhole base station 1 receives the signal.

As described above, according to the first embodiment of the present invention, since the wireless repeater is provided at the intersection or the like, it is possible to communicate with the mobile terminal even in the area that cannot be covered by the manhole base station. Further, if a wireless repeater is provided above the intersection, it is less likely to be affected by obstacles and the like, and radio wave propagation characteristics are improved. Further, since interference is unlikely to occur between manhole base stations, the wireless repeater can perform relays with a small number of frequencies.

When the wireless repeater 8 is provided at the intersection, the construction of the pillar becomes a problem. Therefore, providing the wireless repeater 8 and the antenna 9 in the traffic light 14 has an advantage that the construction of the pillar is unnecessary. Further, since there are traffic lights at almost all intersections in urban areas, there is an advantage that there is no need to worry about the construction site of the radio base station 8, and from the point of view of strength, it is sturdy and safe. In addition, since the traffic signal 14 is generally installed in a place where the pedestrian and the car have good visibility, it can be said that the environment is suitable for installing the wireless repeater 8 from the viewpoint of radio wave propagation. Further, since the signal light source 14 has a power supply for lighting the signal device 14, there is an advantage that it can also be used as the power source of the wireless repeater 8.

Embodiment 2 of the Invention Embodiment 2 of the invention
Will be described. FIG. 12 is a diagram for explaining the second embodiment of the present invention. In the figure, 10 is a diversity antenna, which is connected to the wireless repeater 8.

The shape of the diversity antenna is appropriately determined according to the diversity method used. For example, in the case of performing space diversity, as shown in FIG. 13, monopole antennas of the same shape are arranged at appropriate intervals so that the antenna correlation coefficient becomes low. Further, when performing polarization diversity, two dipole antennas are arranged horizontally and vertically as shown in FIG. Further, in the case of performing the angle diversity, the two directional antennas are oriented in different directions, as shown in FIG. When frequency diversity is performed, the input from one antenna is divided into two frequency components by a bandpass filter, a lowpass filter, and a highpass filter, as shown in FIG. Further, in the case of performing time diversity, as shown in FIG. 17, the input from one antenna is made into two types, that is, the output as it is and the output delayed by time by the delay element.

The configuration of the receiver applied to the diversity antenna will be described. FIG. 18 shows the configuration of a selective combining type receiver. Envelopes are obtained for each of the plurality of antennas and compared, and an optimum signal is selected based on the comparison result. FIG. 19 shows the configuration of a receiver of the equal gain combining system. The phases of the reception signals of the plurality of antennas are detected, and the phase shifter adjusts the phases so that the phases of the reception signals match. Then, the plurality of reception signals having the same phase are combined and supplied to the receiver. FIG. 20 shows the structure of a maximum ratio combining receiver. This is a combination of the selective combining method of FIG. 18 and the equal gain combining method of FIG.

Next, the operation will be described. In mobile communication, the radio wave from the mobile terminal 4 undergoes multiple reflection from the surroundings
Fading is generally caused by the influence of diffraction and the like. Therefore, this fading deteriorates the communication quality. Therefore, if the wireless repeater 8 performs diversity reception, the S / N ratio of the received signal can be improved. If the received signal with the improved S / N ratio is transmitted again, the communication quality is improved. Also in the manhole base station 1, fading occurs because the surrounding environment changes because pedestrians and vehicles are moving. Therefore,
The fact that the wireless repeater 8 has the diversity receiving function is useful for improving the communication quality as in the case of receiving the signal from the mobile terminal 4.

Further, it can be considered to use as follows. A radio repeater 8 having no diversity receiving function is used at an intersection where the visibility is relatively good and the traffic volume is small. On the other hand, at an intersection where the radio wave propagation characteristic is poor, the radio with diversity receiving function according to the second embodiment of the present invention is used. The repeater 8 is used. With such a system configuration, the base station cost is reduced.

As described above, according to the second embodiment of the present invention, since the radio repeater is provided with the diversity antenna, fading can be prevented and communication quality is improved.

In the second embodiment of the present invention,
Although not mentioned in the reception diversity of the manhole base station 1 and the mobile terminal 4, if they are also provided with a diversity function, further improvement in communication quality can be expected.

Third Embodiment of the Invention FIG. 21 is a diagram for explaining the third embodiment of the invention. In the figure, 1
1 is an antenna for communication with the manhole base station 1b,
The main beam is directed to one manhole base station 1b. Reference numeral 12 is an antenna for communication with the mobile terminal. Both the communication antennas 11 and 12 are connected to the wireless repeater 8 and arranged above the intersection. A directional antenna is used as the communication antenna 11, and an antenna (for example, a capacitor antenna) that can cover a wide range is used as the communication antenna 12.

FIG. 22 shows an internal block diagram of the radio repeater 8 of FIG. The radio wave from the mobile terminal 4 receives the communication antenna 12
Received at. This received signal is input to the frequency converter 82a via the transmission / reception switch 81a. Frequency converter 82
After performing a predetermined frequency conversion, a outputs the converted signal to the amplifier 83a. The amplifier 83a, after amplifying to a predetermined signal strength, outputs the amplified signal to the antenna 11 via the transmission / reception switch 81b.

On the other hand, the radio wave from the manhole base station 1b is received by the communication antenna 11. This received signal is input to the frequency converter 82b via the transmission / reception switch 81b.
The frequency converter 82b performs a predetermined frequency conversion and then outputs the converted signal to the amplifier 83b. The amplifier 83b, after amplifying to a predetermined signal strength, outputs the amplified signal to the antenna 12 via the transmission / reception switch 81a.

Next, the operation will be described. Since the main beam of the antenna 11 for communication with the manhole base station is directed toward the one manhole base station 1b, the electric field strength in that direction is strong, and the communication quality between the manhole base station 1 and the wireless terminal 8 is not high. This is improved compared to the case where a directional antenna is used.

In the communication system of FIG. 21, since the manhole base station 1 is arranged on the ground surface, the manhole base station 1 is easily affected by the surrounding environment such as a pedestrian, a car, a guardrail, etc., and the communication sensitivity is poor like the portable terminal 4. Since the user cannot make adjustments such as changing the communication position, sufficient attention must be paid to the propagation characteristics with the wireless repeater 8. From this point of view, using a directional antenna as the communication antenna 11 with the manhole base station 1 is more effective when the wireless repeater 8 is transmitting than when using a non-directional antenna. The electric field strength in the direction of 1 increases, and in the case of reception, the reception strength of the signal from the direction in which the manhole base station 1 is present increases, so that the transmission efficiency of radio waves is improved, which is effective.

As the shape of the antenna 12 for communication with the mobile terminal, for example, a non-directional antenna such as a monopole antenna is used and communication is performed with the mobile terminal 4 in all directions around the intersection, or the antenna is oriented along the road. An antenna or the like having a property can be considered.

Fourth Embodiment of the Invention FIG. 23 is a diagram for explaining the fourth embodiment of the invention. In the figure, a plurality of manhole base stations 1b, 1c, 1d are located near the intersection.
Is arranged. The wireless repeater 8 has a plurality of communication antennas 11b, 11c, 1 having a main beam in the direction in which the manhole base stations 1b, 1c, 1d exist.
1d and an antenna 12 for communication with the mobile terminal 4. When there are a plurality of manhole base stations 1, the communication antenna 11 is the manhole base station 1 that communicates.
One for each is installed independently.

FIG. 24 shows an internal configuration diagram of the wireless repeater 8 of FIG. Unlike the configuration of FIG. 22, the duplexer 81b
To the multiplexer / demultiplexer 84, and the communication antennas 11b, 11c, and 11d are connected to the multiplexer / demultiplexer 84. The signal from the mobile terminal 4 is sent to the antenna 12 and the frequency converter 82.
It is input to the multiplexer / demultiplexer 84 via a, the amplifier 83a, and the transmission / reception switch 81b, and is distributed to each of the plurality of antennas 11. Therefore, the signal from the mobile terminal 4 is transmitted to all the manhole base stations 1b, 1c and 1d. On the other hand, a plurality of communication antennas 11b, 11c, 11
The signal from any one of d is transmitted to the mobile terminal 4 via the antenna 12.

Next, the operation will be described. When the antennas 11b, 11c, and 11d that communicate with a plurality of manhole base stations 1b, 1c, and 1d are provided as shown in FIG. 23, for example, the following communication modes are possible. The wireless repeater 8 can select the manhole base station 1b, 1c, 1d near the intersection having the highest reception sensitivity and perform communication. This may be selected at the beginning of one communication, or the manhole base stations 1b, 1c and 1d are sequentially switched and used, so to speak, such as a base station diversity. Antenna 12 for communicating with mobile terminal 4
As such, an omnidirectional antenna capable of communicating with the mobile terminal 4 in an arbitrary direction near the intersection or an antenna having directivity along the road can be considered.

It is considered that the fourth embodiment of the present invention is particularly effective for an intersection having a large traffic volume. In the case of an intersection with a large traffic volume, there is a high possibility that pedestrians, automobiles, etc. will be congested and the manhole base station 1 will be covered with obstacles. In the present invention, since the plurality of manhole base stations 1 and the wireless repeater 8 can communicate with each other, the manhole base station 1 with excellent communication quality can be obtained.
By selecting, it is possible to reduce the possibility that communication will be interrupted and improve the reliability of the system.

The fourth embodiment of the present invention also has the following advantages. When a manhole base station 1 fails, the operation of the system in the service area in the vicinity of the manhole base station 1 is suspended. However, according to the fourth embodiment of the present invention, the wireless repeater 8 is used as a plurality of manhole base stations 1. Since communication is possible, by selecting the manhole base station 1 that has not failed, it is possible to continue the service in the service area in the vicinity where the wireless relay 8 is arranged. This operation method is also effective when inspecting the manhole base station 1 or when performing sewer work with the manhole cover open.

Fifth Embodiment of the Invention FIG. 25 is a diagram for explaining the fifth embodiment of the invention. In FIG.
Is a beam of the transmission / reception antenna 9 connected to the wireless relay station 8 and has directivity characteristics along the road at the intersection.

Next, the operation will be described. Wireless repeater 8
When it is desired to increase the on-road coverage area, an antenna having directivity along the road at the intersection is more effective than an omnidirectional antenna in view of radio wave propagation characteristics. In this case, in transmission, the power density of the transmitted signal along the road becomes high,
For reception, S / of the received signal from the mobile terminal 4 along the road
The N ratio is improved.

The following may be considered as a specific configuration example. In the case of a cross-shaped intersection as shown in FIG. 25, (1) four antennas having a main beam in the front direction are directed along four roads, and (2) two antennas having an 8-shaped directivity are used. (3) An element antenna may be provided with an array feeding circuit and an array antenna having a cross-shaped array directivity may be used.

In the case of a T-shaped intersection, (1) three antennas having a main beam in the front direction are directed along three roads, and (2) an element feeding antenna is provided with an array feeding circuit to form a T-shaped array. It is conceivable to use an array antenna having directivity.

In the case of a Y-shaped intersection, (1) three antennas having a main beam in the front direction are directed along three roads, and (2) an array feed circuit is provided for the element antennas to form a Y-shaped array. It is conceivable to use an array antenna having directivity.

As described above, according to the fifth embodiment of the present invention, since the antenna having the antenna pattern having the shape matching the shape of the road is used for the wireless relay station, the on-road coverage area of the wireless relay is increased. it can.

As described in the third and fourth embodiments of the invention, it is also possible to separately provide an antenna for communicating with the manhole base station 1 and apply the present invention to an antenna for communication with the mobile terminal 4. Is. In this case, a highly reliable communication system can be obtained in a wide service area.

[0067]

As described above, according to the first aspect of the present invention, since it is impossible to directly communicate between the manhole antenna and the mobile communication terminal, both the manhole antenna and the mobile communication terminal can be used. It is equipped with a repeater installed in a structure on the road at a communicable position, and because communication between the manhole antenna and the mobile communication terminal is performed via the repeater, communication between the mobile communication terminal and There is an effect that the radio wave propagation characteristic can be improved and the communication quality can be improved.

According to the second aspect of the present invention, the repeater is provided with a plurality of antennas, and diversity reception processing for preventing fading is performed based on the received signals of the plurality of antennas, so that further improvement in communication quality is expected. The effect is that you can do it.

According to the invention of claim 3, the repeater comprises a directional antenna having a main beam in the direction of the manhole antenna, and an antenna having wide directivity for communicating with the mobile communication terminal. Therefore, the manhole base station and the radio repeater have directivity characteristics suitable for each, and the communication quality is improved.

Further, according to the invention of claim 4, the main beam is provided with a plurality of directional antennas respectively pointing to a plurality of manhole antennas, and a signal from the mobile communication terminal is transmitted to the plurality of directional antennas. Since it transmits to all of the plurality of manhole antennas via the above, and receives signals from any of the plurality of manhole antennas by the plurality of directional antennas and transmits them to the mobile communication terminal, communication quality is good. A manhole base station can be selected, which has the effect of increasing the reliability of the system.

Further, according to the invention of claim 5, the radiation pattern of the antenna for the repeater to perform communication is a radiation pattern having a main beam along the road. Therefore, communication quality along the road is improved. Has the effect of improving.

Further, according to the invention of claim 6, since the repeater is installed by using the traffic signal at the intersection, there is no need to construct a pillar of the wireless repeater, and the cost is reduced. is there.

According to the invention of claim 7, when the manhole antenna directly receives a signal from the mobile communication terminal and also receives a signal from the mobile communication terminal via the repeater, Since either one of the signals having stronger signal strength is selected, the signal having a good reception condition can be selected, and the communication quality is further improved.

Further, according to the invention of claim 8, the manhole antenna receives the signal from the mobile communication terminal directly at the first frequency, and receives the signal of the mobile communication terminal via the repeater. When receiving at the second frequency, one of the signals that does not cause fading is selected, so that a signal with a good reception condition can be selected, and the communication quality is further improved.

[Brief description of drawings]

FIG. 1 is an operation explanatory diagram of the first embodiment of the invention.

FIG. 2 is an example of an antenna provided in a manhole base station or a wireless repeater according to the first embodiment of the invention (capacitor antenna).

FIG. 3 is an example of an antenna provided in a manhole base station or a wireless repeater according to the first embodiment of the invention (dipole antenna).

FIG. 4 is an example of an antenna provided in the manhole base station or the wireless repeater according to the first embodiment of the invention (microstrip antenna).

FIG. 5 is an example of a coverage area of a manhole base station for explaining the operation of the first embodiment of the invention (in the case of a crossroads).

FIG. 6 is an example of a coverage area of a manhole base station for explaining the operation of the first embodiment of the invention (in the case of a T-junction).

FIG. 7 is an example of a coverage area of a manhole base station for explaining the operation of the first embodiment of the invention (in the case of a Y-junction).

FIG. 8 is an internal configuration diagram of the wireless relay device according to the first embodiment of the present invention.

FIG. 9 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 10 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 11 is an explanatory diagram of an arrangement of wireless repeaters according to the first embodiment of the invention.

FIG. 12 is an operation explanatory diagram of the second embodiment of the present invention.

FIG. 13 is an example of a diversity antenna used in the second embodiment of the invention.

FIG. 14 is another example of the diversity antenna used in the second embodiment of the invention.

FIG. 15 is another example of the diversity antenna used in the second embodiment of the invention.

FIG. 16 is another example of the diversity antenna used in the second embodiment of the invention.

FIG. 17 is another example of the diversity antenna used in the second embodiment of the invention.

FIG. 18 is an example of a diversity receiver used in the second embodiment of the invention.

FIG. 19 is another example of the diversity receiver used in the second embodiment of the invention.

FIG. 20 is another example of the diversity receiver used in the second embodiment of the invention.

FIG. 21 is an operation explanatory diagram of the third embodiment of the present invention.

FIG. 22 is an internal configuration diagram of a wireless repeater according to a third embodiment of the invention.

FIG. 23 is an operation explanatory diagram of the fourth embodiment of the present invention.

FIG. 24 is an internal configuration diagram of a wireless repeater according to a fifth embodiment of the invention.

FIG. 25 is an operation explanatory diagram of the fourth embodiment of the invention.

FIG. 26 is an explanatory diagram of a mobile communication system using a conventional manhole antenna.

[Explanation of symbols]

1 manhole base station, 2 buildings, 3 roads, 4 mobile terminals, 5 optical fiber network, 6 optical fiber repeater, 7
Media center, 8 wireless repeaters, 9 antennas, 10
Diversity antenna, 11 communication antenna with manhole base station, 12 communication antenna with mobile terminal,
13 A directional beam along the road.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Harada 6-23-1305 Konandai, Konan-ku, Yokohama-shi, Kanagawa Prefecture (72) Yoji Shimizu 2-3-2502 Satsukidaira, Misato-shi, Saitama ( 72) Inventor Hiroaki Miyashita 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Inventor Shuji Urasaki 2-3-3, Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Inventor Shigeru Makino 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Inventor Takayoshi Furuno 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Inventor Yoshiyuki Chatani 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Inside Sanryo Electric Co., Ltd.

Claims (8)

[Claims] 1. A mobile communication system using a manhole antenna including a manhole antenna configured inside a manhole cover attached to sewer, and a mobile communication terminal for communicating with the manhole antenna, wherein the manhole antenna includes: In the case where direct communication cannot be performed with the mobile communication terminal, a repeater installed on a structure on the road at a position communicable with both the manhole antenna and the mobile communication terminal is provided. A mobile communication system using a manhole antenna, wherein communication is performed between the manhole antenna and the mobile communication terminal via a repeater. 2. The mobile communication using a manhole antenna according to claim 1, wherein the repeater includes a plurality of antennas, and performs diversity reception processing for preventing fading based on received signals of the plurality of antennas. system. 3. The repeater comprises a directional antenna having a main beam in the direction of the manhole antenna, and an antenna having wide directivity for communicating with the mobile communication terminal. A mobile communication system using the described manhole antenna. 4. A plurality of directional antennas each having a main beam directed to a plurality of manhole antennas, and a signal from the mobile communication terminal is transmitted through the plurality of directional antennas to the plurality of manhole antennas. 4. The transmission to all, the signals from any one of the plurality of manhole antennas are received by the plurality of directional antennas and transmitted to the mobile communication terminal.
A mobile communication system using the described manhole antenna. 5. The mobile communication using the manhole antenna according to claim 1, wherein the radiation pattern of the antenna for the repeater to communicate is a radiation pattern having a main beam along a road. system. 6. The relay according to claim 1, wherein the relay is installed by using a traffic signal at an intersection.
A mobile communication system using the manhole antenna according to claim 1. 7. The manhole antenna receives the signal directly from the mobile communication terminal and, when receiving the signal from the mobile communication terminal via the repeater, either one of the signals having a stronger signal strength. A mobile communication system using a manhole antenna according to any one of claims 1 to 5, wherein a signal is selected. 8. The manhole antenna receives a signal from the mobile communication terminal directly at a first frequency and receives a signal from the mobile communication terminal at a second frequency via the repeater. The mobile communication system using the manhole antenna according to any one of claims 1 to 5, wherein one of the signals that does not cause fading is selected.