JPH08317461A - Mobile communication system - Google Patents

Abstract

PURPOSE: To perform mobile communication by making radio waves reach a radio wave blind zone within a cell or a sector without exerting adverse influence on another area within the same cell or sector or redesigning the cell or the sector. CONSTITUTION: Since a forward base station 18 is installed in the radio wave blind zone 16 of the sector S1 within the cell 10 and the radio frequency signals of a frequency allocated to the other sector S3 are branched and transmitted to the forward base station 18, radio interference with the other area within the same sector S1 is not caused and thus, the other radio wave blind zone is not derivatively generated within the sector S1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, a car telephone,
The present invention relates to an improvement of a mobile communication system that communicates by a mobile phone such as a mobile phone, and more particularly to a mobile communication system that reinforces radio waves in a dead band within a plurality of cells or sectors obtained by dividing a service area.

[0002]

2. Description of the Related Art In a mobile communication system such as a car telephone, a service area is divided into a plurality of cells and a base station is installed for each cell in order to increase a subscriber capacity. The same frequency is repeatedly used to effectively use radio waves. Further, each cell is composed of a plurality of sectors that are divided by a sector antenna to enhance directivity, and each cell is
The radio frequency signals of the frequency assigned to each sector are used to reduce the amount of mutual interference.

In such a mobile communication system, there are radio dead zones in which the assigned radio frequency signals are hard to arrive within a plurality of sectors of each cell. Examples of such radio dead zones include, on the ground, highways, railways,
There are inside tunnels such as general roads, inside buildings, high-rise or middle-rise buildings in semi-underground structure zone, mountain areas, valleys, etc. is there. Conventionally, some countermeasures have been taken to enable effective communication in such a radio dead zone.

As shown in FIG. 8, according to one countermeasure of the prior art, a plurality of optical repeaters 320 are installed between a radio base station or forward base station 300 and a dead band 330, and these optical repeaters 320 are installed. Reference numeral 320 denotes an optical radio frequency signal transmitter / receiver 32 on the base station side, which are mutually connected by an optical fiber C300.
2 and an optical radio frequency signal transmitter / receiver 324 on the mobile station side, and the optical frequency signal transmitter / receiver 322 on the base station side is
The optical frequency signal transmission / reception device 324 on the mobile station side is installed at a position where radio waves from the base station 300 can be received and transmits / receives signals to / from the base station 300 via the antenna A322. Signals are transmitted / received to / from the radio dead zone 330 (optical repeater booster system). In FIG. 8, reference numeral 314 is a mobile telephone, and reference numeral 326 is a duplexer.

In another prior art countermeasure, as shown in FIG. 9, a leaky coaxial cable 34 is provided near the radio dead zone 330.
0 is installed, and the leaky coaxial cable 340 is installed in the base station 3
This relay amplifier 342 is connected to a relay amplifier 342 installed at a position where the radio wave from 00 can be received.
Receives a signal with the base station 300 via the antenna A 342 (leaky coaxial cable relay booster system).

[0006] Still another conventional countermeasure means is shown in FIG.
As shown in FIG. 5, a radio wave reflector 352 is installed on the roof of a building 350 or the like that can receive radio waves in the vicinity of the radio dead zone 330, and between the base station 300 and the radio dead zone 330 via the radio wave reflector 352. Send and receive radio frequency signals (radio relay system).

[0007] Further, according to another conventional countermeasure,
As shown in FIG. 11, a forward base station 362 is installed from the radio base station 300 via the optical transmission device 360 using the radio dead zone 330 as one cell, and an optical cable C360 is provided between the forward base station 362 and the radio dead zone 330. Signals are transmitted via the optical fiber (optical repeater cell system). In FIG. 11, reference numeral 364 is a duplexer.

[0008]

However, the optical repeater booster system, the leaky coaxial cable relay booster system, and the radio relay system all relay to the radio dead zone 330 at the same frequency in the same sector, so only the radio dead zone is used. Not only that, but the radio waves will also leak into the area where the radio waves have been reaching up to now (radio sensitive zone), so that the radio dead zone 330 and the radio sensitive zone will interfere with each other at the same frequency, and as a result, a new electric field will be generated. There was a drawback that an area (radio wave dead zone) where the radio wave could not reach due to weakened intensity was derived.

In addition, the optical repeater cell system has a drawback in that the cell / sector that has been designed with a unified pattern must be redesigned to design a cell / sector with a new pattern.

The problem to be solved by the present invention is to prevent radio waves from entering the dead zone without causing adverse effects by causing radio wave interference in other areas within the same cell or sector and without redesigning the cell or sector. An object of the present invention is to provide a mobile communication system capable of performing mobile communication as it arrives.

[0011]

A first problem solving means of the present invention is to install a forward base station in a radio dead zone in a specific sector in the same cell of a plurality of cells obtained by dividing a service area, It is an object of the present invention to provide a mobile communication system characterized by branching and transmitting a radio frequency signal of a frequency assigned to a sector other than a specific sector in the same cell to a forward base station in the radio dead zone.

A second means for solving the problems of the present invention is to install a forward base station in a radio dead zone in a specific cell among a plurality of cells obtained by dividing a service area, and to set the forward base station in this radio dead zone. It is an object of the present invention to provide a mobile communication system characterized by branching and transmitting a radio frequency signal of another cell to which a frequency different from the frequency assigned to a specific cell is assigned.

A third means for solving the problems of the present invention is to install a forward base station in a radio dead zone within a specific sector in the same cell of a plurality of cells obtained by dividing a service area, and to advance the radio dead zone. To provide a mobile communication system characterized by branching and transmitting a radio frequency signal of a sector in another cell to which a frequency different from a frequency assigned to a specific sector is assigned to a base station. .

A fourth problem solving means of the present invention is the mobile communication system according to any one of the first to third problem solving means, wherein the forward base station is a relay having a relay antenna in another cell or sector. An object of the present invention is to provide a mobile communication system characterized in that a radio frequency signal is transmitted through the device.

A fifth problem solving means of the present invention is the mobile communication system according to any one of the first to fourth problem solving means, wherein the forward base station determines the strength of radio waves transmitted and received by the forward base station. An object of the present invention is to provide a mobile communication system characterized by being adjustable.

[0016]

As described above, since the radio frequency signal of the frequency assigned to another sector or cell is branched and transmitted to the sector or radio dead zone in each cell in the service area, the same sector or cell No radio wave interference with other areas is generated, and thus no other radio dead zone is generated in this cell or sector.

Further, since the forward base station transmitting / receiving a signal to / from the radio dead zone can adjust the intensity of the radio wave transmitted / received by the forward base station, the radio wave reaches according to the width of the dead zone. The area can be easily adjusted.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Referring to the drawings, an embodiment of the present invention will be described in detail. FIG. 1 systematically shows an apparatus for implementing a mobile communication system according to the present invention. In the illustrated embodiment, each of a plurality of cells 10 (only one cell is shown in FIG. 1) obtained by dividing the service area is provided in a plurality of sectors, for example, three cells in the illustrated embodiment. Sectors S1 to S
It is shown that the present invention is applied to the form of 1 cell / 3 sectors divided into three parts. In FIG. 1, reference numeral 12 is a base station of the cell 10, A1 to A3 are sector antennas for transmitting and receiving radio frequency signals assigned to the respective sectors S1 to S3, and reference numeral 14 is a mobile telephone.

A frequency R is assigned to each of the sectors S1 to S3.
F1, RF2 and RF3 are assigned respectively,
These frequencies are generally represented by f + X · Q,
F of the frequencies RF1, RF2, R3 is f1, f2, f3
Represented by For example, f1 = 1500 MHz,
f2 = 1501 MHz, f3 = 1502 MHz,
Also, X = 300 KHz, and Q = 1, 2, 3, 4--.
--N (n is a positive integer).

In the mobile communication system of the present invention, basically, the forward base stations 18 are installed in the radio dead zones 16 of the sectors S1 to S3 in the same cell 10, and each sector S
A radio frequency signal having a frequency RF assigned to another different sector in the same cell 10 is branched and supplied to the forward base stations 18 of 1 to S3 so that the radio signal can be transmitted and received within the radio dead zone 16. .

More specifically, the forward base station 18 installed in the radio dead zone 16 of the sector S1 in the cell 10 branches the signal of the frequency RF3 allocated to another different sector S3 in the same cell 10. The forward base station 18 which is transmitted through the optical cable C3 and is similarly installed in the radio dead zone 16 of the sector S2 in the cell 1 has a frequency RF1 assigned to another different sector S1 in the same cell 10.
Signal is split and transmitted via the optical cable C1, and the forward base station 18 installed in the radio dead zone 16 of the sector S3 in the cell 1 has another different sector S2 in the same cell 10.
The signal of the frequency RF2 assigned to is branched and transmitted via the optical cable C2.

In the embodiment of FIG. 1, for example, cell 10
In the sector S2 within the frequency R represented by f2 + X · Q
Although the radio frequency signal of F2 is assigned, the forward base station 18 is installed in the radio dead zone 16 of this sector S2,
This forward base station 18 is provided with another sector S1 in the same cell 10.
Since the radio frequency signal of the frequency RF1 of f1 + X · Q assigned to is transmitted via the optical cable C1, the mobile telephone 14 in the sector S2 communicates by transmitting radio waves via the antenna A18 of the forward base station 18. be able to.
As described above, since mobile communication in the radio dead zone 16 in the sector S2 is performed by the radio frequency signal of the frequency RF1 that does not interfere with the frequency RF2 assigned to the sector S2, the radio communication is performed in the areas other than the radio dead zone 16 of the sector S2. Area does not interfere with the radio frequency signal of the frequency RF2 used in the area (2), and therefore a new area (radio wave dead zone) in which the electric field is weakened and radio waves cannot reach is not generated.

Further, since the forward base station 18 in the radio dead zone 16 in the sector S2 can adjust the intensity of the radio wave, the propagation range of the radio wave which the forward base station 18 can transmit and receive must be adjusted. Therefore, it is understood that the width of the radio dead zone 16 can be easily adjusted.

Similarly, in the sector S3 in the cell 10, the radio frequency signal of the frequency RF3 represented by f3 + X.Q is assigned, but the same cell is assigned to the forward base station 18 in the radio dead zone 16 of the sector S3. Since the radio frequency signal of the frequency RF2 of f2 + X · Q assigned to the other sector S2 in 10 is transmitted through the optical cable C2, the mobile telephone 14 in the sector S3 transmits the signal through the antenna A18 of the forward base station 18. It is possible to communicate by transmitting radio waves. Also in this case, the mobile communication in the radio dead zone 16 in the sector S3 is performed by the radio frequency signal of the frequency RF2 that does not interfere with the frequency RF3 assigned to the sector S3, so that the mobile communication in the areas other than the radio dead zone of the sector S2 is performed. It does not interfere with the radio frequency signals used in the area, and likewise does not induce a new radio dead zone.

Further, since the forward base station 18 of the radio dead zone 16 in the sector S2 can adjust the intensity of the radio wave, the propagation range of the radio wave which the forward base station 18 can transmit and receive must be adjusted. Therefore, it is understood that the strength of the radio wave can be easily adjusted to the width of the radio dead zone 16.

Similarly, the radio dead zone 16 in the sector S3 is the frequency RF assigned to the sector S2.
Since the radio frequency signal of No. 2 is branched and transmitted, there is no radio wave interference in this sector S3 and this sector S3
Mobile communication can be performed within the radio dead zone 16 within the area 3.
Further, similarly, the forward base station 18 of the radio dead zone 16 can adjust the intensity of the radio wave to match the width of the radio dead zone 16.

In the above embodiment, for example, sector S2
Although the radio frequency signal of the frequency RF1 assigned to the sector S1 is branched and transmitted to the forward base station 18 of the radio dead zone 16, the radio frequency signal of the frequency RF3 assigned to the sector S3 is branched and transmitted. Of course, in this case, the frequency RF1 assigned to the sector S1 is assigned to the forward base station 18 in the radio dead zone 16 of the sector S3 accordingly.
Of the radio frequency signal of 2 is branched and transmitted, and to the forward base station 18 of the radio dead zone 16 of the sector S1, the radio frequency signal of frequency RF2 allocated to the sector S2 is branched and transmitted.

FIG. 2 shows an example in which the present invention is applied to a one-cell / multi-sector configuration in which four or more sectors per cell. In the embodiment of FIG. 2 also, although not shown, the forward base station is installed in the radio dead zone of each sector, and a radio frequency signal of a frequency assigned to another sector is branched and transmitted to each forward base station. To be done.

FIG. 2 (A) shows that the present invention is applied to the one-cell / four-sector form, and frequencies RF2, RF3 assigned to sectors S2, S3, S4 are assigned to forward base stations within the radio dead zone of sector S1. Any one of the frequencies RF3, RF4, and RF1 assigned to the sectors S3, S4, and S1 is assigned to the forward base station within the radio dead zone of the sector S2 by branching any radio frequency signal of RF4 and transmitting it via the optical cable. A radio frequency signal is branched and transmitted via an optical cable, and in the same manner, any of the radio frequencies RF4, RF1, RF2 assigned to the sectors S4, S1, S2 is assigned to the forward base station within the radio dead zone of the sector S3. The frequency signal is branched and transmitted via an optical cable, and the forward base stations within the radio dead zone of sector S4 are assigned to sectors S1, S2, and S3. Wavenumber RF1, RF2, branches either radio frequency signal RF3 is transmitted through an optical cable.

Also in the embodiment of FIG. 2A, as in the embodiment of FIG. 1, mobile communication in the radio dead zone within each sector is
Since it is performed by the radio frequency signal of the frequency that does not interfere with the frequency assigned to this sector, it does not interfere with the radio frequency signal of the frequency used in the area other than the radio dead zone in the sector.

FIG. 2B shows an example in which the present invention is applied to the form of 1 cell and 6 sectors, and FIG. 2C shows an example in which the present invention is applied to the form of 1 cell and 8 sectors. In any of the embodiments, the numbers shown in parentheses of each sector are assigned to other sectors other than the own sector to be branched and transmitted to the forward base station within the radio dead zone of the sector. The numbers attached to the frequency RF are shown. For example, FIG.
In (B), “2” indicates a signal frequency RF2 that can be transmitted to the forward base station in the radio dead zone in the other sectors S1 and S3 to S6 except the sector S2. The description is omitted.

A variant of the invention is shown in FIG. 3, which variant corresponds to the variant of the embodiment of FIG. In this modification, the forward base station 18 in the radio dead zone 16 does not directly transmit the radio frequency signal branched from another sector through the optical cable, but transmits the radio wave corresponding to the radio frequency signal to be branched. Relay antenna 20 for transmitting and receiving
To the repeater 22 having optical cables C1 to C, respectively.
A radio frequency signal is transmitted / received (transmitted) via the wireless communication unit 3. Note that, in FIG. 3, the same reference numerals as those in FIG. 1 indicate the same portions, and the radio frequency signals of the frequencies RF1 to RF3 similar to those in the embodiment of FIG.

As shown in FIG. 3, the relay device 22 having the relay antenna 20 is installed in an area where the radio waves from the sector antennas A1 to A3 reach the respective sectors S1 to S3. Optical cables C1 to C3 are connected to the cable 18.

More specifically, in the illustrated embodiment, the
The forward base station 18 of the radio dead zone 16 of the sector S1 is connected via the optical cable C3 to the relay device 22 installed at a position where the radio wave reaches from the sector antenna A3 of the sector S3, and the forward movement of the radio dead zone 16 of the sector S2. Base station 18
Is the relay device 22 similarly installed in the sector S1.
, And the forward base station 18 in the radio dead zone 16 of the sector S3 is similarly connected via the optical cable C2 of the relay device 22 installed in the sector S2.

The operation of the modification of FIG. 3 is exactly the same as that of the embodiment of FIG. 1. For example, in the sector S2 in the cell 10, a radio frequency signal of frequency RF2 represented by f2 + X.Q is transmitted. Although assigned, in the dead zone 16 of the sector S2, the forward base station 18 receives the radio frequency signal of the frequency RF1 of f1 + X · Q assigned to the other sector S1 in the same cell 10 as the relay device 22 and the optical cable C1. Thus, in the sector S2, the mobile telephone 14 can communicate by transmitting radio waves via the antenna A18 of the forward base station 18. The relay device 22 transmits and receives radio waves of a radio frequency signal of frequency RF1 in the sector S1 via the relay antenna 20. Similarly, in mobile communication within the radio dead zone 16 of the other sectors S3 and S1, the radio frequency signals of the frequencies RF2 and RF3 allocated to the sectors S2 and S3 other than that sector are similarly transmitted to the optical cables C2 and C3 and the relay device. It is carried out by transmitting through 20. Also in this modification, the forward base station 18 can adjust the strength of the radio wave, and thus the propagation range of the radio wave that can be transmitted and received by the forward base station 18 can be adjusted.

An example in which the present invention is applied to a radio dead zone in a cell is shown in FIGS. In the embodiment of FIG. 4, two cells 100A and 100B to which different frequencies RF100A and RF100B are respectively allocated are shown, and the forward base station 180 is installed in the radio dead zone 160 in one cell 100A, and the cells 100A and 100B are arranged in this cell 100A. In the forward base station 180, the radio frequency signal of the frequency RF100B assigned to another different cell 100B is branched and transmitted via the optical cable C100B, and the forward base station 180 is installed in the radio dead zone 160 of the cell 100B in the same manner. , The forward base station 180 in this cell 100B has another different cell 1
The radio frequency signal of the frequency RF100A assigned to 00A is branched and transmitted via the optical cable C100A. In FIG. 4, reference numeral 120 indicates a base station of each cell, and reference numeral A120 indicates its antenna.

In the embodiment of FIG. 4, for example, the cell 10
In 0A, a radio frequency signal of frequency RF100A is assigned, but the radio dead zone 16 of this cell 100A is
Since the radio frequency signal of the frequency RF100B assigned to the other cell 100B is branched and transmitted to the forward base station 180 in 0 through the optical cable C100B, the cell 10
Within the 0 A radio dead zone 160, mobile communication can be performed by transmitting radio waves via the antenna A 180 of the forward base station 180. In this case, the mobile communication in the radio dead zone 160 in the cell 100A is performed by the radio frequency signal of the frequency RF100B that does not interfere with the frequency RF100A assigned to the cell 100A, and thus the mobile communication in the cell other than the radio dead zone 160 of the cell 100A is performed. It does not interfere with the radio frequency signal of the frequency RF100A used in the area. In the mobile communication within the radio dead zone 160 of the cell 100B, the assigned frequency RF1 is similarly set.
Since the radio frequency signal of the allocated frequency RF100A of the cell 100A that does not interfere with 00B is branched and transmitted, mobile communication can be performed in the cell 100B without interfering with each other in all areas including the radio dead zone. You can

In addition, the radio dead zone 160 in the cell 100A
Since the forward base station 180 can adjust the intensity of the radio wave, the forward base station 180 can adjust the propagation range of the radio wave that the forward base station 180 can transmit and receive, and thus the width of the radio dead zone 160 can be easily adjusted. Can be adjusted to

A modified example of the embodiment of FIG. 4 is shown in FIG. 5. In this modified example, the forward base station 180 in the radio dead zone 160 receives a radio frequency signal branched from another cell via an optical cable. Instead of being transmitted directly, the radio frequency signal is transmitted and received via the optical cables C100A and C100B to the relay device 220 having the relay antenna 200 that transmits and receives the radio wave corresponding to the radio frequency signal to be branched. There is. In FIG. 5, the same reference numerals as those in FIG. 4 indicate the same parts, and the cells 100A, 10
0B is the same frequency RF10 as in the embodiment of FIG.
Radio frequency signals of 0A and RF100B are assigned. The relay device 220 is similar to the embodiment of FIG. 3, and the antenna A120 of the base station 120 of the cells 100A and 100B.
Needless to say, it is installed within the range where radio waves from

The operation of this modification of FIG. 5 is exactly the same as that of the embodiment of FIG.
Although the radio frequency signal of the frequency RF100A is assigned, the forward base station 180 installed in the radio dead zone 160 of the cell 100A receives the radio frequency signal of the frequency RF100B assigned to the cell 100B.
0 and the optical cable C100B, and thus the forward base station 1 in the radio dead zone 160 in the cell 100A.
It is possible to communicate by transmitting radio waves via the antenna A180 of 80. The relay device 220 includes the relay antenna 20.
Radio waves of a radio frequency signal of frequency RF 100B are transmitted and received in the cell 100B via 0. Hereinafter, other cells 10
Similarly, in mobile communication within the radio dead zone 160 of 0B, the radio frequency signal of the frequency RF100A assigned to the cell 100A other than the cell is transmitted to the optical cable C100A.
And transmitted via the relay device 200. Even in this modification, the forward base station 180 can adjust the strength of the radio wave, and thus the propagation range of the radio wave that the forward base station 180 can transmit and receive can be adjusted.

Yet another embodiment of the present invention is shown in FIG. In the embodiment of FIG. 6, the present invention is applied to a form of 1 cell / 3 sectors in which a plurality of cells 100A and 100B obtained by dividing a service area are respectively divided into three sectors S1 to S3. When there is a radio dead zone 160 in a specific sector S1 in the cell 100B, the forward base station 180 is installed in this radio dead zone 160, and the forward base station 180 in this radio dead zone 160 has another cell 100
A radio frequency signal of a frequency assigned to a sector other than the sector S1 corresponding to the specific sector S1 in A, for example, S3 is branched and transmitted via the optical cable C100A. Sectors S1 to S3 of cell 100A or cell 1
If there is a similar radio dead zone in the other sector S2 or S3 of 00B, a forward base station is installed in that radio dead zone, and a sector of a different frequency of cell 100B or cell 100A is similarly assigned to the forward base station. Radio frequency signals are branched and transmitted.

The operation of this embodiment is similar to that of the embodiment shown in FIGS. 1 and 4, and in this embodiment as well, mobile communication is carried out by transmitting radio waves through another cell 100A within the radio dead zone of the cell 100B. You can In this case, cell 1
Since the mobile communication in the radio dead zone 160 in 00B is performed by the radio frequency signal of the frequency RF100A that does not interfere with the frequency RF100B assigned to the cell 100B, it is used in the area other than the radio dead zone 160 of the cell 100B. It does not interfere with radio frequency signals.

A modified example of the embodiment of FIG. 6 is shown in FIG. 7. In this modified example, the forward base station 180 in the radio dead zone 160 transmits the radio frequency signal branched from another cell 100A via an optical cable. Instead of being transmitted directly,
A radio frequency signal is transmitted / received to / from a relay device 220 having a relay antenna 200 for transmitting / receiving a radio wave corresponding to the radio frequency signal to be branched, via an optical cable C100A. In FIG. 7, the same reference numerals as those in FIG. 6 indicate the same parts, and the cells 100A, 100B
Sectors S1 and S2 of the same frequency RF100A1 to RF100A3, RF10 similar to the embodiment of FIG.
Radio frequency signals of 0B1 to RF100B3 are assigned. The relay device 220 has the antenna A3 of the base station 120 of the cell 100A, as in the embodiment of FIGS.
Needless to say, it is installed within the range where radio waves from

In the above embodiment, the radio frequency signal is branched and transmitted from one cell or sector to the radio dead zone of another cell or sector in a one-to-one relationship. The radio frequency signals may be branched and transmitted to the cells or sectors in a 1-to-N relationship, and N to N may be transmitted from a plurality of cells or sectors to a plurality of other cells or sectors.
Alternatively, the radio frequency signal may be branched and transmitted in the relationship of N to M.

[0045]

As described above, according to the present invention, a radio frequency signal of a frequency assigned to another sector or cell is branched to a sector within each cell of the service area or a radio dead zone within the cell. Since the data is transmitted, it does not interfere with other areas in the same sector or cell, and therefore, no other dead band is generated in this cell or sector. Further, unlike the conventional optical repeater cell system, there is no need to redesign the cell / sector that has been designed with a unified pattern to design a cell / sector with a new pattern, and a communication system in a dead band Is easy to design.

Further, since the forward base station which transmits and receives signals to and from the radio dead zone can adjust the intensity of the radio wave transmitted and received by the forward base station, the radio wave reaches according to the width of the dead zone. The real benefit is that the area can be easily adjusted.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of a first embodiment of the present invention for branching and transmitting a radio frequency signal assigned to another sector in a radio dead zone within a sector of one cell of a mobile communication system.

FIG. 2 is a schematic system diagram of three examples which are substantially the same as the embodiment of FIG. 1 but differ in the number of sectors in one cell. FIG. 6B shows an example in which the present invention is applied to 1 cell and 6 sectors, and FIG. 7C shows an example in which the present invention is applied to 1 cell and 8 sectors.

FIG. 3 is a schematic system diagram of a modified example of the embodiment of FIG.

FIG. 4 is a schematic system diagram of a second embodiment of the present invention for branching and transmitting a radio frequency signal assigned to another cell in a radio dead zone within a cell of a mobile communication system.

5 is a schematic system diagram of an example in which the embodiment of FIG. 4 is modified.

FIG. 6 is a schematic system diagram of a third embodiment of the present invention for branching and transmitting a radio frequency signal assigned to a sector of another cell in a radio dead zone within one sector of one cell of a mobile communication system. is there.

FIG. 7 is a schematic system diagram of a modified example of the embodiment of FIG.

FIG. 8 is a schematic system diagram of one prior art mobile communication system using an optical repeater booster system.

FIG. 9 is a schematic system diagram of another conventional mobile communication system using a leaky coaxial cable relay booster system.

FIG. 10 is a schematic system diagram of still another conventional mobile communication system using a radio relay system.

FIG. 11 is a schematic system diagram of still another conventional mobile communication system using an optical repeater cell system.

[Explanation of symbols]

 10 cell 12 base station 14 mobile phone 16 radio dead zone 18 forward base station 20 relay antenna 22 relay device 100A cell 100B cell 120 base station 160 radio dead zone 180 forward base station 200 relay antenna 220 relay device A1 to A3 antenna A18 antenna A120 antenna A180 Antenna C1 to C3 Optical cable S1 to S6 Sector 300 Radio or forward base station 314 Mobile phone 320 Optical repeater 322 Base station optical radio frequency transceiver 324 Mobile station optical radio frequency transceiver 326 Duplexer 330 Radio dead zone 340 Leaky coaxial cable 342 Repeater amplifier 350 Building 352 Reflector 360 Optical transmission device 361 Forward base station A324 Antenna A342 Antenna C300 Optical cable

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hirofumi Yoneyama 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (5)

[Claims] 1. A forward base station is installed in a radio dead zone in a specific sector in the same cell of a plurality of cells obtained by dividing a service area, and the forward base station in the radio dead zone is provided in the same cell. A mobile communication system characterized by branching and transmitting a radio frequency signal of a frequency assigned to a sector other than a specific sector. 2. A forward base station is installed in a radio dead zone within a specific cell among a plurality of cells obtained by dividing a service area, and the forward base station in the radio dead zone is assigned to the specific cell. A mobile communication system, which branches and transmits a radio frequency signal of another cell to which a frequency different from the frequency is assigned. 3. A forward base station is installed in a radio dead zone in a specific sector in the same cell of a plurality of cells obtained by dividing a service area, and the forward base station in the radio dead zone is assigned to the specific sector. A mobile communication system, which branches and transmits a radio frequency signal of a sector in another cell to which a frequency different from the assigned frequency is assigned. 4. The mobile communication system according to claim 1, wherein the forward base station transmits the radio frequency through a relay device having a relay antenna in the other cell or sector. A mobile communication system, wherein a signal is transmitted. 5. The mobile communication system according to claim 1, wherein the forward base station is capable of adjusting the intensity of radio waves transmitted and received by the forward base station. Mobile communication system.