JPH05136724A - Mobile body radio communication system - Google Patents

Abstract

PURPOSE:To provide the mobile body radio communication system by forming a smaller radio zone than that of a conventional system and accommodating more mobile terminal equipments. CONSTITUTION:A radio control station 1 and each radio base station 10 are connected through an optical transmission line 90, and the radio control station 1 uses an information signal to modulate signals of plural radio frequencies used by each radio base station 10 and to multiplex each modulation signal and to apply electro-optical conversion to the multiplexed optical signal and sends the result to each radio base station 10 via the optical transmission line 90 and each base station applies photoelectric conversion to the received optical signal and sends the result to each of mobile terminal stations 31 33 as a radio signal. In the mobile radio communication system as above, each radio base station 10 forms small radio zones 21-23 not overlapped with each other and each small radio zone forms one radio zone 20, and a radio signal of the same frequency group comprising plural frequencies is used between each radio base station 10 and each of mobile terminal stations 31-33 to implement radio communication in each small radio zone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a car telephone system,
The present invention relates to a mobile radio communication system such as a mobile phone system and a personal communication system.

[0002]

2. Description of the Related Art In a conventional mobile radio communication system such as a car phone and a mobile phone system, a radius of 5 km is used.
The wireless zone of the degree is formed by one wireless base station, and UHF
Wireless communication was performed using the frequency band.

[0003]

In such a configuration of the radio base station, a relatively high transmission output power is required, and therefore the radio base station apparatus becomes large in size and the manufacturing cost becomes high. was there. Moreover, since communication is performed using the UHF frequency band, there is a limit to the usable frequency band. Therefore, in a mobile radio communication system accommodating a huge number of mobile phones and the like, it is necessary to expand the frequency band to be used as compared with the conventional frequency band. In addition, since the transmission output power is expected to decrease with the downsizing of mobile phones, it is necessary to greatly reduce the distance between the radio base station and mobile terminals such as mobile phones.

An object of the present invention is to solve the above problems and provide a mobile radio communication system capable of accommodating a larger number of mobile terminals by forming a smaller radio zone than the conventional one. Especially.

[0005]

According to a first aspect of the present invention, there is provided a mobile radio communication system, wherein a radio control station and each radio base station are connected via an optical transmission line.
Signals of a plurality of radio frequencies used in each radio base station are converted to optical signals after being multiplexed with each modulated signal modulated by an information signal, and transmitted to each of the radio base stations via the optical transmission path, Each of the base stations is a mobile wireless communication system in which the transmitted optical signal is photoelectrically converted and radiated to each mobile terminal station as a radio signal, and each of the radio base stations forms a small radio zone that does not overlap each other. Then, one radio zone is formed by each of the small radio zones, and radio signals of the same frequency group composed of a plurality of frequencies are transmitted between the radio base stations and the mobile terminals in each of the small radio zones. It is characterized in that wireless communication is performed by using it.

A mobile radio communication system according to a second aspect of the present invention is a mobile radio communication system according to the first aspect, which includes a plurality of radio base station groups each including a plurality of the radio base stations. It is characterized in that the station groups form wireless zones that do not overlap each other, and wireless communication is performed using wireless signals of different frequency groups in each of the wireless zones.

[0007]

In the conventional car telephone system and mobile telephone system, as is well known, the frequency band of 800 to 900 MHz is used. Adjacent wireless zones use different frequency groups to prevent interference and are separated from each other. In addition, the same frequency group is repeatedly used in each wireless zone to improve frequency utilization efficiency. On the other hand, in the present invention, attention is paid to the fact that, for example, a building or road made of concrete or the like does not reflect but rather absorbs millimeter-wave radio waves, and within one wireless zone (for example, 20 in FIG. 1). Small wireless zones (eg, 21 in FIG. 1,
22 and 23), the same frequency group F1 is repeatedly used. Regarding the millimeter wave absorption characteristics, for example,
Kazumi Awa et al. "Experiment on reflection characteristics of building interior materials in millimeter wave band" Technical Report of IEICE, AP90-1, 1
Reported in April 990.

In the mobile radio communication system according to claim 1, since the optical transmission line is used as a signal transmission line between the radio control station and each radio base station, the subcarrier frequency is microwave. Whether it ’s a millimeter wave,
The transmission characteristics of the signal are not affected by the frequency used in each radio zone, so that more mobile terminals can be accommodated and a wideband signal such as a television signal can be transmitted. In addition, in the system, each radio base station need only include at least a photoelectric converter, an electro-optical converter, a transmission power amplifier, a reception low noise amplifier, and an antenna, in addition to the optical branching and combining device, for example. Therefore, the device can be downsized as compared with the conventional radio base station of a car phone and a mobile phone system, and each radio base station device can be installed in, for example, a tower of a telephone station.

Further, in the mobile radio communication system according to claim 2, preferably, the mobile radio communication system according to claim 1 includes a plurality of radio base station groups each including a plurality of the radio base stations, The respective wireless base station groups form wireless zones that do not overlap each other, and wireless communication is performed using wireless signals of different frequency groups in the respective wireless zones. by this,
The service area of the system can be increased.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 is a block diagram of a mobile radio communication system according to a first embodiment of the present invention.

In the mobile radio communication system of the first embodiment, the radio base stations 11, 12 and 13 form small radio zones 21, 22 and 23 adjacent to each other, respectively. One wireless base station group 10 corresponding to one wireless base station and composed of three wireless base stations 11, 12 and 13 forms one wireless zone 20, and each small wireless zone 21, 2
2 and 23, the radio control station 1 connected to the switching center of the mobile radio communication system uses the same frequency group F1 composed of a plurality of frequencies in the millimeter wave band, for example, through the optical fiber cables 90 to 92. Each radio base station 11, 1
It is characterized in that it is connected to 2, 13. In the drawings of the present application, a wireless zone is indicated by a chain line, and a small wireless zone obtained by dividing the wireless zone is indicated by a solid line. In this embodiment, each small wireless zone 21, 2
The radii 2 and 23 are about 100 m to 200 m, and the radius of the wireless zone 20 of the present embodiment corresponding to the wireless zones of the conventional car phone and mobile phone systems is about 1.5 km to 5 km.

As shown in FIG. 1, the radio base station 11 is
The wireless base station 12 includes a wireless device 11a, an antenna 11b, and an optical branching / combining device 11c. The wireless base station 12 includes a wireless device 12a, an antenna 12b, and an optical branching / combining device 12c. 13a, an antenna 13b, and an optical branching / combining device 13c. Here, the wireless devices 11a, 1
Each of 2a and 13a includes at least a photoelectric converter, an electro-optical converter, a transmission power amplifier, and a reception amplifier.

In the radio control station 1, each radio base station 1
1, 12 and 13 radio equipments 11a, 12a and 13a which are transmitted from the radio equipments 11a, 12a and 13a are frequency-multiplexed and high-frequency signals are FM-modulated by a call signal, and the combined multiplexed signal is electronically transmitted. The converted optical signal is transmitted to the optical branching / combining unit 11c of the wireless base station 11 via the optical fiber cable 90. The optical branching / combining device 11c branches a part of the transmitted optical signal to generate an optical fiber cable 93.
The optical signal is transmitted to the wireless device 11a via the optical fiber cable 91 while being transmitted to the wireless device 11a via the optical fiber cable 91.
2 to the optical branching / combining device 12c. Optical splitter / combiner 12
c branches a part of the transmitted optical signal and outputs it to the wireless device 12 a via the optical fiber cable 94, while transmitting the transmitted optical signal to the wireless base station 13 via the optical fiber cable 92. Machine 13a. Each radio 11
a, 12a, and 13a photoelectrically convert the transmitted optical signals into the original high-frequency signals of the frequency group F1 and then amplify the power and output from the antennas 11b, 12b, and 13b, which are adjacent to each other but do not overlap with each other. Wireless zone 2
It radiates toward mobile terminals 31, 32 and 33 at 1, 22 and 23. On the other hand, the high frequency signals radiated from the mobile terminals 31, 32 and 33 are transmitted to the radio base stations 11 and 12,
The signals are received by the wireless devices 11a, 12a, 13a via the antennas 11b, 12b, 13b of 13 and are transmitted from the wireless base stations 11, 12, 13 to the optical branching / combining device 11c, contrary to the signal path of the previous transmission system. It is transmitted to the radio control station 1 via 12c and the optical fiber cables 90 to 92. In this case, signal processing opposite to that in the transmission system is performed, such as the photoelectric conversion processing in the wireless control station 1, while the wireless devices 11a, 12a, and 13a perform the electro-optical conversion processing.

FIG. 2 is a specific block diagram of the transmission system of the mobile radio communication system shown in FIG. here,
Each wireless base station 11, 12, 13 of the wireless base station group 10
In the small wireless zones 21, 22, and 23 formed by, for example, a frequency group F1 including three frequencies f1, f2, and f3 in the millimeter wave band is used. As the frequency in the receiving system, for example, a frequency in the millimeter wave band, which is shifted from the frequencies f1, f2, and f3 by a predetermined frequency, is used.

As shown in FIG. 2, in the radio control station 1, each baseband signal B1, B2, B which is a call signal.
3 is input to each FM modulator 50a, 50b, 50c. The FM modulator 50a is a carrier signal generator 51a.
The carrier wave signal of frequency f1 generated in 1 is FM-modulated according to the input baseband signal, and the FM-modulated signal is output to the combiner 52. The FM modulator 50b FM-modulates the carrier signal of the frequency f2 generated by the carrier signal generator 51b according to the input baseband signal,
The FM modulated signal is output to the combiner 52. Furthermore, F
The M modulator 50c FM-modulates the carrier signal of the frequency f3 generated by the carrier signal generator 51c according to the input baseband signal, and outputs the FM-modulated signal to the combiner 52. The combiner 52 frequency-multiplexes each of the three input FM modulation signals and combines them, and then outputs the multiplexed signal of the frequency group F1 to the laser diode 53 which is an electro-optical conversion element. The laser diode 53 electro-optically converts the input multiplexed signal into an optical signal, and then transmits the optical signal via the optical fiber cable 90 to the optical branching device 41 of the wireless base station 11.
transmit to c.

The optical branching device 41c branches a part of the transmitted optical signal and outputs the branched optical signal to the photoelectric converter 41a composed of, for example, a photodiode, and the transmitted optical signal is transmitted through the optical fiber cable 91 to the wireless base station. It is transmitted to the optical branching device 42c of the station 12. Next, the optical branching device 42c branches a part of the transmitted optical signal and outputs the branched optical signal to the photoelectric converter 42a, and the transmitted optical signal is transferred to the photoelectric converter of the wireless base station 13 via the optical fiber cable 92. 43a.

In the radio base station 11, the photoelectric converter 41
a converts the input optical signal into the original multiplexed signal, and transmits the small wireless zone 2 through the power amplifier 41b and the antenna 11b.
1, and the radiated multiplexed signal is transmitted to the mobile terminal 31.
Then, the mobile terminal 31 selectively extracts and receives a high frequency signal of, for example, the frequency f1 designated by a predetermined procedure from the multiplexed signal. In addition, the wireless base station 12
Similar to the wireless base station 11, is equipped with an optical branching device 42c, a photoelectric converter 42a, a power amplifier 42b, and an antenna 12b, and operates similarly. Further, the wireless base station 13 is similar to the wireless base station 11 in that the photoelectric converter 43a and the power amplifier 4 are provided.
3b and antenna 13b are provided and operate in the same manner. Here, in the small radio zones 21, 22, and 23 formed by the radio base stations 11, 12, and 13, the radio base stations 11, 12, and 13 and the mobile terminals 31 use the same frequency group F1. , 32, 33 are wirelessly communicated.

Although the transmission system of the mobile radio communication system has been described above with reference to FIG. 2, the reception system can be similarly configured by using a device that performs signal processing reverse to that of the transmission system.

By the way, a larger number of mobile terminals are
In order to accommodate in one wireless zone, it is necessary to increase the number of channels for wireless communication. Further, in order to increase the number of channels, a wide wireless band is necessary, which inevitably requires a high subcarrier frequency in optical transmission. For example, 1.5 GHz
When a video signal that requires a band of 4 MHz in an analog band is transmitted in an analog manner, if the required band is set to 36 MHz, a frequency band of 100 waves requires a band of 3600 MHz, for example, a subcarrier frequency of 1.5 GHz band. Cannot be set. Furthermore, when increasing the number of subcarrier frequencies, it is necessary to use the frequency band from the microwave to the millimeter wave. For example, when 60 GHz of a millimeter wave is used as the subcarrier frequency, 140 waves can be transmitted if the usable band is about 5 GHz. Needless to say, the number of channels that can be transmitted is further increased by narrowing the band, although the conditions are different when a signal narrowing band technique is applied.

As described above, each small wireless zone 21, 2
Since 2 and 23 are formed by dividing the conventional wireless zone, the radii of the small wireless zones 21, 22 and 23 are reduced, which reduces the transmission output power of each mobile terminal station and reduces each mobile station. The device of the terminal station can be downsized.

In the present embodiment, as a signal transmission path between the radio control station 1 and each radio base station 11, 12, 13,
Since the optical fiber cables 90 to 92 are used, whether the subcarrier frequency is microwave or millimeter wave, the transmission characteristics of the signal are not affected by the frequency used in each radio zone, and as described above. This has the advantage that more mobile terminals can be accommodated and broadband signals can be transmitted. In addition, in the transmission system of the system, each wireless base station 11, 12, 13
In addition to the optical branching devices 41c and 42c, at least the photoelectric converters 41a, 42a and 43a and the power amplifier 41, respectively.
b, 42b, 43b and antennas 11b, 12b, 13b
Since it is only necessary to include and, it is possible to downsize the device as compared with the conventional radio base station of a car phone and a mobile phone system, and equip each radio base station device to, for example, a tower of a telephone station. There is an advantage that you can.

Although the high frequency signals are frequency-multiplexed in the first embodiment described above, the present invention is not limited to this, and the high frequency signals may be time-division multiplexed. In addition, each small wireless zone 2
In Nos. 1, 22 and 23, a plurality of mobile terminals may be assigned to one frequency wave using a time division multiplexing method.

FIG. 4 is a plan view showing an embodiment of the wireless zone in the city in the first embodiment shown in FIG. As shown in FIG. 4, the wireless zone 20 including the small wireless zones 21 to 28 is provided on the road between the buildings 200 in the city.
Are formed. An optical fiber cable is laid under each road, and optical signals are branched and combined at a plurality of points. The shape of the wireless zone 20 can be set arbitrarily, and FIG. 4 is an example thereof.

<Second Embodiment> FIG. 3 is a block diagram of a mobile radio communication system according to a second embodiment of the present invention. As shown in FIG. 3, three radio base station groups 110, 120 and 130 are connected to the radio control station 101 via optical fiber cables 95, 96 and 97. First
The wireless base station group 110 uses the frequency group F1 to form a wireless zone 111 including five small wireless zones 112. The second wireless base station group 120 uses a frequency group F2 different from the frequency group F1 to form a wireless zone 121 including six small wireless zones 122. Furthermore, the third radio base station group 130 is
A frequency group F3 different from 1 and F2 is used to form a wireless zone 131 composed of five small wireless zones 132. Here, the wireless zones 111, 121, 131 formed by the respective wireless base station groups 110, 120, 130 are formed so as not to overlap each other.

The wireless zones 111, 121, 13
1 uses the same frequency group, but if there is no problem in interference, the wireless zone 111 and the wireless zone 13 are used.
The same frequency group may be used for 1 and 2. As a result, it is possible to make effective use of frequencies and build a flexible network.

FIG. 5 is a plan view showing an embodiment of the wireless zone in the city in the second embodiment shown in FIG. As shown in FIG. 5, wireless zones 111, 121, 131, 141 each including a small wireless zone (not shown in FIG. 5) are formed on a road between buildings 200 in the city. An optical fiber cable is laid under each road, and optical signals are branched and combined at a plurality of points. Here, each wireless zone 111, 121, 13
1, 141 use different frequency groups, but the wireless zone 121 and the wireless zone 131 may use the same frequency group as long as there is no problem in terms of radio wave interference.

<Third Embodiment> FIG. 6 is a block diagram of a mobile radio communication system according to a third embodiment of the present invention. The third embodiment is a case where the mobile radio communication system according to the present invention is applied to each floor of a four-story building 300.

As shown in FIG. 6, a radio base station group 301 and an optical branching / combining device 311 are provided on the first floor of the building 300.
A wireless base station group 302 and an optical branching / combining device 312 are provided on the second floor, a wireless base station group 303 and an optical branching / combining device 313 are provided on the third floor, and a wireless base station group 304 is provided on the fourth floor. For example, in the transmission system, the optical signal output from the radio control station 1 is transmitted to the optical branching / combining device 311 on the first floor via the optical fiber cable 321, and the optical branching / combining device 311 is transmitted.
Splits a part of the transmitted optical signal and transmits it to the wireless base station group 301 through the optical fiber cable 331, while transmitting the transmitted optical signal to the optical fiber cable 322.
To the optical branching / combining device 312 on the second floor. Here, the optical branching / combining device 312 branches a part of the transmitted optical signal and transmits it to the wireless base station group 302 via the optical fiber cable 332, while transmitting the transmitted optical signal to the optical fiber cable 323. Optical branching / combining device 31 on the 3rd floor
3 is transmitted. Further, the optical branching / combining device 313 branches a part of the transmitted optical signal to generate an optical fiber cable 333.
While transmitting the optical signal to the wireless base station group 303 via the optical fiber cable 324, the optical signal is transmitted to the wireless base station group 304 on the fourth floor via the optical fiber cable 324.

On the other hand, in the receiving system, the optical signal output from each of the base station groups 301 to 304 is the optical fiber cable 3
31 to 333, 321 to 324, and the optical branching / combining device 3
11 to 313 to the radio control station 1.
In this case, signal processing opposite to that of the previous transmission system is performed.

Although each of the radio base station groups 301 to 304 uses the same frequency group F1, if there is a problem in terms of radio wave interference, as shown in FIG. The frequency groups used may be different. In the modification of FIG. 7, the wireless base station group 40 on the first floor
The first and third floor radio base station groups 403 each use the same frequency group F1, while the second floor radio base station group 402 and the fourth floor wireless base station group 404 each use the same frequency group F2. For example, in the transmission system, the radio control station 101
The optical signal output from the optical fiber cable 421 is transmitted to the optical branching / combining device 411 on the first floor via the optical fiber cable 421, and the optical branching / combining device 411 branches a part of the transmitted optical signal to connect the optical fiber cable 423. The optical signal is transmitted to the wireless base station group 401 via the optical fiber cable 422 while being transmitted to the wireless base station group 401 via the optical fiber cable 422.
Further, another optical signal output from the radio control station 101 is transmitted via the optical fiber cable 431 to the optical branching / combining unit 4 on the second floor.
12, the optical branching / combining device 412 branches a part of the transmitted optical signal and transmits it to the wireless base station group 402 via the optical fiber cable 433, while transmitting the transmitted optical signal to the optical fiber. It is transmitted to the wireless base station group 404 on the fourth floor via the cable 432.

As described above, since the devices of each wireless base station group can be downsized, it is possible to easily build a network in a building using the mobile wireless communication system according to the present invention. There are advantages.

FIG. 8 is a block diagram when the mobile radio communication system according to the present invention is applied to a car telephone system. As shown in FIG. 8, the radio control station 510 is connected to the radio base station groups 511, 512, 513 via optical fiber cables 551, 552, 553, respectively, and here, the radio base station groups 511, 512, 512 are connected. 513 wirelessly communicates with the mobile terminal station using mutually different frequency groups F1, F2, and F3. On the other hand, the wireless control station 510
Is connected to a fixed telephone network 540 via a car telephone exchange 530 as is known. In addition, the wireless control station 520
The optical base cables 561, 562, 563 are connected to the radio base station groups 521, 522, 523, respectively, and the radio base station groups 521, 522, 523 are provided with different frequency groups F1, F2, F3, respectively. Wireless communication with the mobile terminal station. On the other hand, the radio control station 5
20 is connected to a fixed telephone network 540 via a car telephone exchange 530 as is known. The fixed telephone network 540 is further connected to an automobile telephone exchange office in another area to form a wide area communication network.

[0034]

As described in detail above, according to the present invention, a radio control station and each radio base station are connected via an optical transmission line,
The radio control station multiplexes each modulated signal obtained by modulating a signal of a plurality of radio frequencies used in each radio base station with an information signal, and then electro-optically converts the modulated signal into an optical signal, and the radio signals are transmitted via the optical transmission path. A mobile radio communication system for transmitting to a base station, wherein each of the base stations photoelectrically converts the transmitted optical signal and radiates a radio signal to each mobile terminal station. A small wireless zone that does not exist, and one wireless zone is formed by each of the small wireless zones. In each of the small wireless zones, the same wireless frequency band is formed between the wireless base stations and the mobile terminals. Wireless communication is performed using wireless signals in the frequency group.

Therefore, since the optical transmission line is used as the signal transmission line between the radio control station and each radio base station, the subcarrier frequency may be microwave or millimeter wave. The signal transmission characteristics are not affected by the frequency used in each wireless zone, so that more mobile terminals can be accommodated and a wideband signal can be transmitted. In addition, in the system, each radio base station is only required to include, for example, at least a photoelectric converter, an electro-optical converter, a transmission power amplifier, a reception amplifier, and an antenna in addition to the optical branching / combining device. The device can be downsized as compared with the conventional radio base station of a car phone and a mobile phone system, and each radio base station device can be mounted on, for example, a telephone tower, a telephone pole, a traffic signal, a ceiling in a building, etc. can do. Further, since each of the small wireless zones is formed smaller than the conventional wireless zone, the radius of each small wireless zone becomes smaller, thereby reducing the transmission output power of each mobile terminal station and each mobile terminal station. There is an advantage that the device can be downsized.

[Brief description of drawings]

FIG. 1 is a block diagram of a mobile radio communication system according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a transmission system of the mobile wireless communication system shown in FIG.

FIG. 3 is a block diagram of a mobile radio communication system according to a second embodiment of the present invention.

FIG. 4 is a plan view showing an embodiment of the wireless zone in the city in the first embodiment shown in FIG.

5 is a plan view showing an embodiment of a wireless zone in a city in the second embodiment shown in FIG. 3; FIG.

FIG. 6 is a block diagram of a mobile radio communication system according to a third embodiment of the present invention.

FIG. 7 is a block diagram showing a modification of the third embodiment shown in FIG.

FIG. 8 is a block diagram when the mobile radio communication system according to the present invention is applied to a car telephone system.

[Explanation of symbols]

1, 101 ... Radio control station, 10 ... Radio base station group, 11, 12, 13 ... Radio base station, 11a, 12a, 13a ... Radio equipment, 11b, 12b, 13b ... Antenna, 11c, 12c ... Optical branching / combining device , 20, 111, 121, 131 ... Wireless zone, 21, 22, 23, 112, 122, 132 ... Small wireless zone, 31, 32, 33 ... Mobile terminal, 41a, 42a, 43a ... Photoelectric converter, 41b, 42b, 43b ... Power amplifier, 41c, 42c ... Optical splitter, 50a, 50b, 50c ... FM modulator, 52 ... Combiner, 53 ... Laser diode, 90 to 97 ... Optical fiber cable, 110, 120, 130 ... Wireless Base station group.

Claims (2)

[Claims] 1. A radio control station is connected to each radio base station via an optical transmission line, and the radio control station modulates a plurality of radio frequency signals used in each radio base station with information signals. After the signal is multiplexed, it is converted into an optical signal by electro-optical conversion and transmitted to each of the radio base stations via the optical transmission path, and each of the base stations photoelectrically converts the transmitted optical signal into a radio signal. A mobile radio communication system radiating to a mobile terminal station, wherein each of the radio base stations forms a small radio zone that does not overlap with each other, and each of the small radio zones forms one radio zone. A mobile wireless communication system, wherein wireless communication is performed between each of the wireless base stations and each of the mobile terminals in a zone by using wireless signals of the same frequency group including a plurality of frequencies. 2. A plurality of radio base station groups each including a plurality of the radio base stations, each of the radio base station groups forming a non-overlapping radio zone, and each of the radio zones having a different frequency. The mobile wireless communication system according to claim 1, wherein wireless communication is performed using a wireless signal of the group.