JP2005168043A - Base station apparatus and relay transmission station apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an optical transmission system for mobile communication having a new configuration that compensates for the shortcomings of a star type and a multi-branch type using a base station apparatus.
A radio modulation / demodulation device (base station device) 3 that performs modulation / demodulation processing between a line network frequency electrical signal and a radio frequency electrical signal is connected to the network 1 via an electrical signal transmission cable 2 so that the radio frequency electrical signal is transmitted. The central station 5 that converts between the optical signal and the optical signal is connected to the relay transmission station 11 that distributes and combines the optical signal via the downstream and upstream optical fiber cables 10a and 10b, and wireless communication with the mobile communication device 8 is performed. A plurality of terminal stations 7 that convert electrical signals and optical signals are connected to the relay transmission station 11 via downstream optical fiber cables 12a and 12b, respectively, so that the central station 5 and the relay transmission station 11 are connected. Are connected by a small number of optical fiber cables, and the relay transmission station 11 and the plurality of terminal stations 7 are respectively connected by optical fiber cables to provide independence.
[Selection] Figure 1

Description

  TECHNICAL FIELD The present invention relates to collection and distribution of radio frequency signals using an optical transmission system, and in particular, uses an optical fiber cable for a mobile communication device in a dead zone where radio waves are difficult to reach such as inside a tunnel, inside an underground mall, inside a building, etc. In particular, the present invention relates to an optical transmission system for mobile communication that transmits a radio signal, and more particularly, to a base station apparatus and a relay transmission station apparatus that constitute the system.

In a mobile communication system such as a car phone or a mobile phone, a base station connected to an upper line network (in the following description, an example is a public line network) and a mobile communication device such as a mobile phone are wirelessly connected. Thus, the mobile communication device can communicate through the public network.
In such a mobile communication system, the mobile communication device can perform good wireless communication with the base station when the mobile communication device is in a place where radio waves are easy to reach, such as outdoors. When in a dead zone where radio waves are difficult to reach, good wireless communication with the base station cannot be performed.

To solve this problem, an antenna is installed in a place where wireless communication with the base station can be satisfactorily performed, and an antenna is also installed in the insensitive area, and a relay amplification device is wired between these antennas and wired. In addition, a device that enables communication between a mobile communication device and a base station in a dead zone by relay amplification, or a wireless modem that is directly connected to the public network and an antenna installed in the dead zone are wired. Thus, a device has been devised that enables communication between a mobile communication device in a dead zone and a public network.
Further, since it is necessary to efficiently transmit a high frequency signal such as 800 MHz or 1.5 GHz band used for a mobile phone, for example, a light weight instead of a metal cable can be used instead of a metal cable for connection between a relay amplifying device or a wireless modem and an antenna. A flexible, low-loss optical fiber cable was used.

Here, the transmission system using the optical fiber cable in this way can be classified into a star type and a multi-branch type from the viewpoint of network topology. Device "(Matsushita Technical Journal, Vol. 44, No. 6 (December 1998)).
Here, a conventional optical transmission system using a wireless modulation / demodulation device will be described with reference to FIG. 7 and FIG.

FIG. 7 shows a star-type optical transmission system for mobile communication. This system includes a wireless modem 3 connected to a public network 1 and an electric signal transmission cable 2 made of a metal cable, Connected to the central fixed station 5 via an optical transmission cable comprising a pair of downstream optical fiber cable 6a and upstream optical fiber cable 6b, respectively, and a central fixed station 5 connected to the modem 3 via an electric signal transmission cable 4. A plurality of fixed terminal stations 7.
In this optical communication system for mobile communication, the terminal fixed station 7 and the mobile communication device 8 arranged in the dead zone are wirelessly communicated, and the terminal fixed station 7 and the central fixed station 5 are connected by an optical transmission cable. Thus, the mobile communication device 8 existing in the dead zone is connected to the public line network 1 via the wireless modem 3.

  That is, in communication in the downstream direction (direction from the line network 1 to the mobile communication device 8) in this optical transmission system for mobile communication, the line frequency electrical signal from the public line network 1 is converted into a modulation transmission unit of the wireless modem 3 31 is modulated into an electric signal of a radio communication frequency, this radio frequency electric signal is converted into an analog optical signal by an electric-optical converter (E / O) 51 of the central fixed station 5, and this analog optical signal is further converted into a star signal. It is branched into a plurality by the coupler 52 and transmitted to each terminal fixed station 7 through each downstream optical fiber cable 6a. In the terminal fixed station 7, the received optical signal is converted and restored to the original radio frequency electrical signal by the optical-electrical converter (O / E) 71, and this radio frequency electrical signal is amplified by the amplifier 72 as necessary. Wirelessly transmitted from the antenna 73 to the mobile communication device 8.

  On the other hand, in the uplink communication (direction from the mobile communication device 8 to the network 1) in this optical communication system for mobile communication, the radio frequency electrical signal wirelessly transmitted from the mobile communication device 8 is transmitted to the terminal fixed station 7. The radio frequency electrical signal received by the antenna 73 is amplified by an amplifier 74 as necessary, and the radio frequency electrical signal is converted into an analog optical signal by an electrical / optical converter (E / O) 75. This optical signal is transmitted to the central fixed station 5 through the upstream optical fiber cable 6b. Reference numeral 76 in the figure denotes an antenna duplexer for sharing the antenna 73 for transmission and reception. The central fixed station 5 converts the optical signal received from each upstream optical fiber cable 6b to the original radio frequency electric signal by the respective optical-electrical converter (O / E) 53, and restores the radio frequency electric signal. The signal is synthesized by the synthesizer 54 and transmitted to the radio modulation / demodulation device 3. The radio modulation / demodulation device 3 demodulates the radio frequency electrical signal into an electrical signal of the line frequency by the reception demodulator 32 and transmits it to the public network 1. .

FIG. 8 shows a multi-branch optical communication system for mobile communication, which includes a radio modem 3 connected via a public line network 1 and an electric signal transmission cable 2 comprising a metal cable, A central fixed station 5 connected in series to a central fixed station 5 connected to the wireless modem 3 via an electric signal transmission cable 4 and a single optical transmission cable composed of a downstream optical fiber cable 6a and an upstream optical fiber cable 6b. And a plurality of terminal fixed stations 7 connected to 5.
In this optical transmission system for mobile communication, similarly to the above star type, the terminal fixed station 7 and the mobile communication device 8 arranged in the dead zone are wirelessly communicated, and the terminal fixed station 7 and the central fixed station 5 are connected. Are connected by an optical transmission cable to connect the mobile communication device 8 existing in the dead zone to the public network 1 via the wireless modem 3.

  However, in the downstream communication in this multi-branch optical communication system for mobile communication, the signal is modulated by the modulation transmitter 31 of the wireless modem 3 and is converted by the electric / optical converter (E / O) 51 of the central fixed station 5. The analog optical signal converted into the analog optical signal is transmitted to each terminal fixed station 7 through a single downstream optical fiber cable 6a without being branched. That is, in each terminal fixed station 7, a part of the optical signal is taken out from the downstream optical fiber cable 6a by the optical branching device 77, and this optical signal is converted into the original radio frequency electric signal by the optical-electrical converter (O / E) 71. The radio frequency electric signal is amplified by the amplifier 72 as necessary, and is wirelessly transmitted from the antenna 73 to the mobile communication device 8.

  Further, in uplink communication in this multi-branch optical communication system for mobile communication, the radio frequency electrical signal received from the mobile communication device 8 by the antenna 73 of the terminal fixed station 7 is amplified by the amplifier 74 as necessary. The radio frequency electrical signal is converted into an analog optical signal by an electrical / optical converter (E / O) 75, and this optical signal is put on the upstream optical fiber cable 6b by an optical synthesizer 78, and is transmitted from another terminal fixed station. And is transmitted to the central fixed station 5. In the central fixed station 5, the optical signal received from each upstream optical fiber cable 6b is converted and restored to the original radio frequency electric signal by the optical-electric converter (O / E) 53, and the radio frequency electric signal is wirelessly converted. The reception demodulator 32 of the modem 3 demodulates to an electric signal having a line frequency and transmits it to the public line network 1.

In the conventional star-type optical transmission system (FIG. 7) as described above, each terminal fixed station 7 is connected to the central fixed station 5 via a pair of optical fiber cables 6a and 6b on the downstream and upstream sides. The station 7 is independent on the optical wiring, and each terminal fixed station 7 can be installed without being restricted by other terminal fixed stations, and each terminal fixed station 7 can be freely moved and removed. There is a degree.
However, the star-type optical transmission system has a problem that the number of required optical fiber cables is large and the cost is high, and that it is difficult to install the optical fiber cable. For example, it is easier to carry out the work by laying a bundle of the required number of optical fiber cables and laying the bundled cables, and the durability of the installed optical fiber cables can be ensured. When a fixed station is to be installed, it may be difficult to secure an unused optical fiber cable from a bundled cable that has already been laid.

Further, in the conventional multi-branch optical transmission system (FIG. 8) as described above, each terminal fixed station 7 is connected to the central fixed station 5 with one optical fiber cable 6a, 6b as the main line. Therefore, the number of optical fiber cables required is reduced as compared with the star method, and there is an advantage that the optical fiber cable can be easily laid together with advantages in terms of cost.
However, in the multi-branch optical transmission system, “Multi-branch optical fiber link for mobile communication using automatic wavelength offset control” by Taruzawa et al. (Technical Report of IEICE Technical Report, RCS94-70 (1994) As described in September)), there are problems related to the generation of optical beat noise associated with the optical synthesis of the upstream optical signal and the setting of the branching ratio of the downstream optical splitter 77 and the combining ratio of the upstream optical combiner 78.

  The problem of optical beat noise is that a frequency component corresponding to the difference in optical frequency of a semiconductor laser normally used as an electrical-to-optical converter (E / O) is generated as noise in the radio frequency band after optical demodulation. In order to avoid this when performing photosynthesis, there is a problem that the optical frequency of the E / O 75 of each terminal fixed station must be controlled so that the generated beat noise does not overlap with the transmitted radio frequency band.

  In addition, each terminal fixed station 7 is connected in series like a single stroke by an optical fiber cable, and each terminal fixed station 7 performs branching-in of an optical signal and synthesis of an optical signal in the middle of this optical fiber cable. If the optical signal intensity inputted to the O / E 71 of the terminal fixed station 7 is made constant and the optical signal intensity outputted from the E / O 75 is made constant, the gain of the amplifier of each terminal fixed station 7 can be made common. , Design and manufacturing costs can be reduced. However, in order to make the optical signal strength constant, the branching ratio of the downstream optical splitter 77 and the combining ratio of the upstream optical combiner 78 must be set differently for each terminal fixed station 7. As a result, when moving or removing some terminal fixed stations or adding new terminal fixed stations, the optical branching ratio and optical combining ratio must be adjusted for the terminal fixed stations of the entire system. In other words, there is a problem that the degree of freedom regarding the installation of the terminal fixed station is extremely poor.

The present invention has been made in view of the above-described conventional circumstances, and an object thereof is to realize a mobile communication optical transmission system having a new configuration that compensates for the disadvantages of the star type and the multi-branch type.
More specifically, the present invention realizes the degree of freedom of installation of terminal stations without considering the optical branching ratio and the light combining ratio as in the star type, and the ease of laying the optical fiber cable as in the multi-branch type Another object of the present invention is to realize an optical transmission system for mobile communication that realizes cost advantages.
Further objects of the present invention will be apparent from the following description.

  The present invention is connected to a plurality of terminal stations that perform wireless communication with a mobile communication device via optical fiber cables, and to a conversion station that performs modulation / demodulation with a network and an optical fiber cable. A relay transmission station apparatus that is connected and performs relay transmission using an optical signal between a terminal station and a conversion station, and a plurality of photoelectric conversion devices that convert the optical signal transmitted from the terminal station through an optical fiber into an electrical signal. A converter, a combiner that combines the electrical signals converted by the photoelectric converter, and a photoelectric converter that converts the combined electrical signal into an optical signal and transmits the optical signal to a conversion station via an optical fiber cable. The relay transmission is performed without performing photosynthesis that causes optical beat noise.

  In addition, the present invention is connected via a fiber optic cable to a relay transmission station that relays a radio signal communicated with a mobile communication device in the form of an optical signal, and performs modulation / demodulation with a network. A fixed-station device connected to a modulation / demodulation device to be connected by a radio or electric signal transmission cable, and converts an electric signal sent from the modulation / demodulation device into an optical signal sent to a relay transmission station via an optical fiber cable And a photoelectric converter that converts an optical signal sent from the relay transmission station via an optical fiber cable into an electric signal sent to the modem.

  In addition, the present invention is connected to a plurality of relay transmission stations that relay and transmit wireless signals communicated with mobile communication devices in the form of optical signals, respectively, via optical fiber cables, and between the network. A fixed station apparatus connected to a modulation / demodulation apparatus for performing modulation / demodulation by a wireless or electric signal transmission cable, a photoelectric converter for converting an electric signal received from the modulation / demodulation apparatus into an optical signal, and the converted optical signal respectively An optical distributor that distributes optical signals to be transmitted to a relay transmission station via an optical fiber cable, and a plurality of photoelectric conversions that convert optical signals transmitted from a plurality of relay transmission stations via an optical fiber cable into electrical signals And a synthesizer that synthesizes the converted electric signals into electric signals to be sent to the modem.

  In addition, the present invention is connected to a plurality of relay transmission stations that relay and transmit wireless signals communicated with mobile communication devices in the form of optical signals, respectively, via optical fiber cables, and between the network. The reception / diversity processing of the received signal from the mobile communication device that is connected to the modulation / demodulation device that performs modulation / demodulation by a wireless or electrical signal transmission cable and that is transmitted via a different relay transmission station is performed by different reception demodulation units provided in the modulation / demodulation device. A fixed station device for performing the processing, which converts an electrical signal sent from the modem to an optical signal, and sends the converted optical signal to the relay transmission station via each optical fiber cable. An optical distributor that distributes the optical signal to be transmitted and an optical signal transmitted from a plurality of relay transmission stations via an optical fiber cable to different reception demodulation units of the modem Configured with a plurality of photoelectric converters for converting each in order of the electrical signal.

  In addition, the present invention provides a relay transmission station apparatus that relays and transmits a radio signal communicated with a mobile communication device in the form of an optical signal, a fixed station apparatus connected via an optical fiber cable, and a circuit network. And a modulation / demodulation device that performs modulation / demodulation between them, and a conversion station device that performs photoelectric conversion and modulation / demodulation of signals according to a plurality of communication methods, wherein the fixed station device uses an optical fiber cable to transmit an electric signal transmitted from the modulation / demodulation device side. Downstream photoelectric converter that converts the optical signal sent from the relay transmission station via the optical fiber cable into the electrical signal sent to the modem side through the optical fiber cable And a modulation / demodulation device, a plurality of modulation transmission units having different communication schemes for modulating a line frequency electric signal received from the line network side into a radio frequency electric signal and sending it to the relay transmission station device side, and A plurality of demodulation receivers having different communication methods for demodulating radio frequency electrical signals sent from the relay transmission station apparatus side into line frequency electrical signals and sending them to the network side, and further, a plurality of modulated transmissions A synthesizer that synthesizes the radio frequency electrical signal sent from the unit and sends it to the downstream photoelectric converter of the fixed station device, and distributes the radio frequency electrical signal sent from the uplink photoelectric converter of the fixed station device to And a distributor for sending out to the demodulating receiver.

  The present invention also relates to a wireless modulation / demodulation apparatus that performs modulation / demodulation between a line frequency electrical signal and a radio frequency electrical signal connected to a circuit network, and between the radio frequency electrical signal and an optical signal connected to the wireless modulation / demodulation apparatus. A central fixed station device that performs conversion, a relay transmission station device that is connected to the central fixed station device via an optical fiber cable and relays an optical signal, and is connected to the relay transmission station device via an optical fiber cable. A mobile station system comprising: a terminal station apparatus that performs conversion between an optical signal and a radio frequency electrical signal and performs radio communication with a mobile phone using a radio frequency electrical signal, the central fixed station apparatus A plurality of relay transmission station apparatuses are distributed and connected to each other, and a plurality of terminal station apparatuses arranged along a main road or the like are connected to each of the relay transmission station apparatuses.

  The present invention also relates to a wireless modulation / demodulation apparatus that performs modulation / demodulation between a line frequency electrical signal and a radio frequency electrical signal connected to a circuit network, and between the radio frequency electrical signal and an optical signal connected to the wireless modulation / demodulation apparatus. A central fixed station device that performs conversion, a relay transmission station device that is connected to the central fixed station device via an optical fiber cable and relays an optical signal, and is connected to the relay transmission station device via an optical fiber cable. A mobile station system comprising: a terminal station apparatus that performs conversion between an optical signal and a radio frequency electrical signal and performs radio communication with a mobile phone using a radio frequency electrical signal, the central fixed station apparatus A relay transmission station device was connected to the relay transmission station device, and a plurality of terminal station devices arranged on the ground floor or basement floor in the building were connected to the relay transmission station device.

Further, in the above mobile phone system, the wireless modem may have a function as a terminal station that directly performs wireless communication with the mobile phone using radio frequency electrical signals.
The following optical transmission system for mobile communication can be constructed using the apparatus according to the present invention.

  An optical transmission system for mobile communication is an optical transmission system for mobile communication in which a mobile communication device that performs radio communication with a terminal station by radio frequency electrical signals is connected to a network via an optical fiber cable. A conversion station that converts between the optical signal and the optical signal is connected to the network via an electric signal transmission cable, and a relay transmission station that distributes and combines the optical signals is connected to the conversion station with optical fiber cables for downstream and upstream. A plurality of terminal stations that perform wireless communication with a mobile communication device and convert between an electric signal and an optical signal by connecting to a relay transmission station via optical fiber cables for downlink and uplink, respectively. The station is connected to a line network via an electric signal transmission cable and performs modulation / demodulation processing between the line frequency electric signal and the radio frequency electric signal, and a radio processed by the radio modulation / demodulation apparatus Configured to include a central station for conversion between an optical signal to be transmitted at wavenumber electric signal and an optical fiber cable, a.

  That is, an optical transmission system for mobile communication that connects a mobile communication device that wirelessly communicates with a terminal station using radio frequency electrical signals to a network via an optical fiber cable, and is connected to the network via an electrical signal transmission cable A wireless modulation / demodulation device that performs modulation / demodulation processing between a line network frequency electrical signal and a radio frequency electrical signal, and a central office that converts a radio frequency electrical signal processed by the wireless modulation / demodulation device and an optical signal transmitted through an optical fiber cable A relay station for connecting and converting optical signals to and from the optical fiber cable for downstream and upstream is connected to the converter station. A plurality of terminal stations that are connected via a mobile communication device and convert between an electric signal and an optical signal to a relay transmission station, respectively. The connection between the conversion station and the relay transmission station is connected with a small number of optical fiber cables as in the multi-branch type, and the relay transmission station and multiple terminal stations are connected. The spaces are connected by optical fiber cables, like a star type, so that they are independent.

Further, in this mobile communication optical transmission system, the wireless modem and the central station are wirelessly connected by a radio frequency electrical signal.
In other words, this mobile communication optical transmission system is configured by wirelessly connecting a wireless modulation / demodulation device and a central station using a radio frequency electrical signal, thereby further improving the freedom of installation of the central station.

Further, in this optical transmission system for mobile communication, the wireless modem device also has a base station function for performing wireless communication with the mobile communication device and connecting the wireless communication device to the line.
In other words, this optical transmission system for mobile communication comprises a base station function for performing wireless communication with a mobile communication device and connecting the wireless communication device to a line by using the wireless modulation / demodulation device. The system design can be facilitated by making it possible to share the base station of the communication system or by using an existing base station for the optical transmission system.

Furthermore, in this optical transmission system for mobile communication, a plurality of radio modulation / demodulation devices are provided according to the communication system, and a plurality of radio frequency electrical signals modulated by the plurality of radio modulation / demodulation devices are synthesized and output to the central station. And a distributor that distributes the radio frequency electrical signal converted by the central office to the corresponding radio modem according to the communication method.
That is, this optical transmission system for mobile communication is provided with a plurality of radio modulation / demodulation devices according to the communication system, and a combination of a plurality of radio frequency electrical signals modulated by the plurality of radio modulation / demodulation devices and output to the central station And a distributor that distributes the radio frequency electrical signal converted by the central office to the corresponding radio modem according to the communication system. For example, in a mobile phone system, an analog system, a digital system, and a TDMA system And a plurality of communication systems such as the CDMA system.

  Further, in this optical communication system for mobile communication, a plurality of relay transmission stations are connected to the conversion station via downlink and uplink optical fiber cables, respectively, and the conversion station converts from a radio frequency electrical signal. An optical distributor that distributes an optical signal to a plurality of optical signals that are transmitted to the relay transmission station by each downstream optical fiber cable, and an optical signal that is transmitted from the plurality of relay transmission stations by the upstream optical fiber cable, respectively. A plurality of photoelectric converters for converting into radio frequency electric signals and an electric combiner for synthesizing a plurality of radio frequency electric signals converted by the plurality of photoelectric converters.

  That is, this optical transmission system for mobile communication connects a plurality of relay transmission stations to a conversion station via downlink and uplink optical fiber cables, respectively, and converts the conversion station from a radio frequency electrical signal. An optical distributor that distributes the signal to a plurality of optical signals that are transmitted to the relay transmission station via each downstream optical fiber cable, and an optical signal that is transmitted from the plurality of relay transmission stations via the upstream optical fiber cable, respectively. Photosynthesis that comprises a plurality of photoelectric converters that convert to frequency electrical signals and an electrical synthesizer that synthesizes multiple radio frequency electrical signals converted by the plurality of photoelectric converters, causing optical beat noise Uplink communication is performed without performing.

  Further, in this optical communication system for mobile communication, a plurality of relay transmission stations are connected to the conversion station via downlink and uplink optical fiber cables, respectively, and the conversion station converts from a radio frequency electrical signal. An optical distributor that distributes an optical signal to a plurality of optical signals that are transmitted to the relay transmission station by each downstream optical fiber cable, and an optical signal that is transmitted from the plurality of relay transmission stations by the upstream optical fiber cable, respectively. A plurality of photoelectric converters for converting into radio frequency electrical signals, and a plurality of receiving units for demodulating each of the plurality of radio frequency electrical signals converted by the plurality of photoelectric converters, and connected to different relay transmission stations A plurality of receiving units perform reception diversity processing on signals from a certain mobile communication device received by a plurality of terminal stations.

  That is, this optical transmission system for mobile communication connects a plurality of relay transmission stations to a conversion station via downlink and uplink optical fiber cables, respectively, and converts the conversion station from a radio frequency electrical signal. An optical distributor that distributes the signal to a plurality of optical signals that are transmitted to the relay transmission station via each downstream optical fiber cable, and an optical signal that is transmitted from the plurality of relay transmission stations via the upstream optical fiber cable, respectively. A plurality of photoelectric converters for converting into frequency electrical signals, and a plurality of receiving units for demodulating each of a plurality of radio frequency electrical signals converted by the plurality of photoelectric converters, to different relay transmission stations With respect to signals from a certain mobile communication device received by a plurality of connected terminal stations, reception diversity processing is performed by the plurality of reception units.

According to the present invention, in a mobile communication optical transmission system, a system configuration similar to a multi-branch type and a system configuration similar to a star type are fused with a relay transmission station interposed therebetween, so that the number of optical fiber cables can be reduced or installed. It is possible to realize the advantages of the multi-branch type such as easy, and the star-type advantages such as a large degree of freedom in installing a plurality of terminal stations.
Furthermore, according to the present invention, in the optical transmission system for mobile communication, the wireless modulation / demodulation device and the central station can be wirelessly connected as described above to increase the degree of freedom of installation thereof. A rational system configuration can be realized by combining with a base station, a plurality of wireless modulation / demodulation devices with different communication systems can be used, and a plurality of different communication systems can be supported. It is possible to avoid the occurrence of optical beat noise that impairs communication quality by performing in signal format, and it is possible to increase reception sensitivity by performing reception diversity by providing a plurality of reception units that receive and process upstream signals, etc. The effect of can be obtained.

  The present invention will be specifically described with reference to examples. In addition, in order to clarify the gist of the present invention, the same parts as those in the conventional configuration shown in FIGS.

FIG. 1 shows the configuration of an optical transmission system for mobile communication according to a first embodiment of the present invention.
In this embodiment, the configuration from the network 1 to the wireless modem 3 and the central fixed station 5 is the same as that of the multi-branch system shown in FIG. The relay transmission station 11 is connected by an optical fiber cable 10a and an upstream optical fiber cable 10b.
The radio modem 3 and the central fixed station 5 constitute a conversion station 9 in the present invention. In this embodiment, the radio modem 3 and the central fixed station 5 are connected via an electric signal transmission cable 4. However, in the present invention, the radio modulation / demodulation device 3 and the central fixed station 5 may be configured as an integrated device.

Further, in this embodiment, a plurality of terminal fixed stations 7 are connected to the relay transmission station 11 by a pair of downstream and upstream optical fiber cables 12a and 12b, respectively, and this part is the star type system shown in FIG. This is similar to the configuration in which each terminal fixed station is connected to the central fixed station.
The relay transmission station 11 is provided with an optical distributor (star coupler) 110 that distributes the optical signal transmitted from the central fixed station 5 to each downstream optical fiber cable 12a, and is wirelessly transmitted by the E / O 51 of the central fixed station 5. The downstream optical signal converted from the frequency electrical signal is transmitted from the relay transmission station 11 to the O / E 71 of each terminal fixed station 7 through each downstream optical fiber cable 12a.

Each relay transmission station 11 is provided with a plurality of optical-electrical converters (O / E) 111 connected to the upstream optical fiber cable 12b. The upstream optical signal converted from the signal is converted and restored to the original radio frequency electric signal by each O / E 111.
Then, the relay transmission station 11 includes a synthesizer 112 that synthesizes the radio frequency electrical signal converted and restored by each O / E 111, and an optical-electrical power that converts the synthesized radio frequency electrical signal into an upstream optical signal again. The converter (O / E) 113 is provided, and the radio frequency electrical signals from the plurality of mobile communication devices 8 received by the terminal fixed stations 7 are combined and converted into upstream optical signals, and the upstream optical fiber cable 10b is connected. Via the O / E 53 of the central fixed station. As described above, in this embodiment, since optical signals are reconverted into an electrical signal format and synthesized, optical beat noise is avoided.

According to the optical transmission system having the above-described configuration, by providing the relay transmission station 11, the optical transmission is performed from the conversion station 9 to the relay transmission station 11 by the pair of upstream and downstream optical fiber cables 10a and 10b. Advantages similar to the multi-branch type such as easy installation are obtained, and along with this, optical transmission is performed from the relay transmission station 11 to each terminal fixed station 7 by a pair of upstream and downstream optical fiber cables 12a and 12b, Similar to the star type in which each terminal fixed station 7 is obtained independence and a high degree of freedom of installation is realized, and each terminal fixed station can be easily installed even in an installation place of an intricate structure such as an underground shopping center. Benefits are gained.
Note that the terminal fixed station 7 of the present embodiment is provided with a transmitting antenna 73a and a receiving antenna 73b for wireless communication with the mobile communication device 8, and thus an antenna duplexer 76 is provided. However, it may be configured as in the conventional example shown in FIG.

  In the downlink communication according to the present embodiment, the line frequency electric signal from the line network 1 is modulated into a radio frequency electric signal by the modulation transmission unit 31 of the radio modulation / demodulation device 3, and this radio signal electric signal is converted to E of the central fixed station 5. / O51 is converted into an analog optical signal and transmitted to the relay transmission station 11 through a single downstream optical fiber cable 10a. In the relay transmission station 11, this optical signal is branched by the star coupler 110 and transmitted to each terminal fixed station 7 through each downstream optical fiber cable 12a. In each terminal fixed station 7, the received optical signal is transmitted by the O / E 71. The original radio frequency electrical signal is converted and restored, and the radio frequency electrical signal is amplified by an amplifier 72 as necessary, and is wirelessly transmitted from the transmitting antenna 73a to the mobile communication device 8.

  In the uplink communication according to the present embodiment, the radio frequency electrical signal wirelessly transmitted from the mobile communication device 8 is received by the receiving antenna 73b of the terminal fixed station 7, and the received radio frequency electrical signal is received by the amplifier 74. The radio frequency electrical signal is amplified as necessary, converted into an analog optical signal by the E / O 75, and this optical signal is transmitted to the relay transmission station 11 through the upstream optical fiber cable 12b. Then, the relay transmission station 11 converts this optical signal into a radio frequency electrical signal by the O / E 111, combines these radio frequency electrical signals by the synthesizer 112, and converts them again to an optical signal by the E / O 113 to obtain a single signal. It is transmitted to the central fixed station 5 through the upstream optical fiber cable 10b. Then, the central fixed station 5 converts and restores the optical signal received from each upstream optical fiber cable 10b to the original radio frequency electrical signal by the O / E 53, transmits this radio frequency electrical signal to the radio modulation / demodulation device 3, and transmits the radio signal. In the modem 3, the radio frequency electric signal is demodulated into a line frequency electric signal by the reception demodulator 32 and transmitted to the public line network 1.

FIG. 2 shows the configuration of an optical transmission system for mobile communication according to a second embodiment of the present invention.
In addition, since a present Example added the change to 1st Example, description about the part similar to 1st Example is abbreviate | omitted, and a changed part is demonstrated.
In this embodiment, a plurality (two in this example) of relay transmission stations 11 having the same configuration as in the first embodiment are provided, and a plurality of relay transmission stations 11 having the same configuration as in the first embodiment are provided for these relay transmission stations 11. The terminal fixed station 7 is connected by a pair of downstream and upstream optical fiber cables 12a and 12b, respectively, as in the first embodiment.

  Further, the central fixed station 5 of this embodiment is provided with an optical distributor (star coupler) 52 that distributes the optical signal converted by the E / O 51 in the same number as the relay transmission station 11, and each distributed optical signal is provided. Is transmitted to each relay transmission station 11 through each downstream optical fiber cable 10a. Further, the central fixed station 5 of this embodiment is provided with the same number of O / Es 53 as the relay transmission stations 11, and each O / E 53 receives an optical signal from each relay transmission station 11 through the upstream optical fiber cable 10b. The radio frequency electrical signals transmitted and converted by the respective O / Es 53 are synthesized by the synthesizer 54 and transmitted to the reception demodulator 32 of the radio modulation / demodulation device 3.

According to the optical transmission system having the above configuration, the same advantages as those of the first embodiment can be obtained, and the plurality of relay transmission stations 11 can be arranged in different directions with the central fixed station 5 interposed therebetween. The installation of a plurality of terminal fixed stations 7 as a center can be realized without requiring a very long optical fiber cable, and a large number of terminal fixed stations 7 can be easily distributed over a wide area in an underground shopping street having an intricate structure. There is.
The downlink and uplink communication according to the present embodiment is performed for each relay transmission station 11 in the same manner as in the first embodiment, but optical beat noise is not generated by the combiner 54 in the uplink communication. Signal synthesis in the signal format is performed.

FIG. 3 shows the configuration of an optical transmission system for mobile communication according to a third embodiment of the present invention.
In addition, since a present Example added the change to 2nd Example, description about the part similar to 2nd Example is abbreviate | omitted, and a changed part is demonstrated.
In this embodiment, similarly to the second embodiment, a plurality of relay transmission stations 11 (two in this example) are provided, and upstream optical signals (that is, from the mobile communication device 8) transmitted from these relay transmission stations 11 are provided. Receive diversity is performed on the received signal). In this embodiment, each terminal fixed station 7 is preferably arranged so that at least two terminal fixed stations 7 connected to different relay transmission stations 11 can receive radio signals from the same mobile communication device 8.

  In order to perform such reception diversity, the central fixed station 5 of this embodiment is provided with the same number of O / E 53 as the relay transmission station 11, and each O / E 53 is connected to each relay through the upstream optical fiber cable 10b. An optical signal is transmitted from the transmission station 11. Further, the radio modulation / demodulation device 3 of the present embodiment is provided with the same number of reception demodulation units 32 as the number of O / Es 53, and each reception demodulation unit 32 receives an upstream radio frequency electric signal from a different O / E 53. Receive diversity is performed.

FIG. 4 shows the configuration of the main part of an optical transmission system for mobile communication according to a fourth embodiment of the present invention.
Since this embodiment is a modification of the first embodiment so as to support a plurality of (two in this example) communication methods, the description of the same parts as the first embodiment is omitted. The changed part will be described.
In the present embodiment, a plurality of wireless modems 3 having different communication methods are provided, a combiner 13 that combines the downlink radio frequency electrical signals from the modulation transmitters 31 of each wireless modem 3, and the central fixed station 5. A distributor 14 is provided that distributes the upstream radio frequency electrical signal from the radio signal to the demodulation receiver 32 of each radio modem 3.

  That is, in this embodiment, downlink radio frequency electrical signals of different communication schemes modulated by the respective radio modulation / demodulation devices 3 are synthesized by the synthesizer 13, and the central fixed station 5, the relay transmission station 11, and the terminal fixed station 7 are combined. And is wirelessly transmitted to the mobile communication device 8 and received by the mobile communication device 8 of the corresponding communication method. The signal received by the terminal fixed station 7 from the mobile communication device 8 is transmitted via the relay transmission station 11 and the central fixed station 5 and distributed by the distributor 14, and is transmitted by the wireless modem 3 of the corresponding communication method. It is converted into a line frequency electric signal and transmitted to the line network 1.

FIG. 5 shows an example in which the present invention is applied to a mobile phone system.
In this application example, by applying the second embodiment of the present invention, two relay transmission stations (HUB) are distributed and connected to one radio modem (BTS) and central fixed station (M / U), A large number of terminal fixed stations (S / U) are installed in a wide area along a trunk road, etc., and the communication area of one base station consisting of a radio modem (BTS) and a central fixed station (M / U) Equivalently expanding.

FIG. 6 shows another example in which the present invention is applied to a mobile phone system.
In this application example, a relay transmission station (HUB) is connected to a base station composed of a radio modem (BTS) and a central fixed station (M / U), and a large number of terminals fixed to the relay transmission station (HUB) are fixed. A station (S / U) is installed in each ground floor, underground, and underground passage in the building, and the base station communication area is equivalent to the interior and underground space that is a dead zone in the base station. Is expanding.

1 is a configuration diagram of an optical transmission system for mobile communication according to a first embodiment of the present invention. It is a block diagram of the optical transmission system for mobile communication based on 2nd Example of this invention. It is a block diagram of the optical transmission system for mobile communication based on 3rd Example of this invention. It is a block diagram of the principal part of the optical transmission system for mobile communication based on 4th Example of this invention. It is a figure which shows the structure of an example which applied this invention to the mobile telephone system. It is a figure which shows the structure of another example which applied this invention to the mobile telephone system. It is a figure which shows the example of 1 structure of the conventional star type | system | group system. It is a figure which shows the example of 1 structure of the conventional multi-branch type | system | group.

Explanation of symbols

1: network, 3: wireless modem,
5: Central fixed station, 7: Terminal fixed station,
8: Mobile communication device,
10a, 12a: Downstream optical fiber cable,
10b, 12b: upstream optical fiber cable,
11: Relay transmission station,

Claims (2)

A wireless modem that performs modulation / demodulation between line frequency electrical signals and radio frequency electrical signals connected to the network, and a central fixed that performs conversion between radio frequency electrical signals and optical signals connected to the wireless modem A station apparatus, a relay transmission station apparatus that is connected to a central fixed station apparatus via an optical fiber cable to perform relay transmission of an optical signal, and an optical signal and a radio frequency that are connected to the relay transmission station apparatus via an optical fiber cable. A base station device that constitutes an optical transmission system for mobile communication, comprising: a terminal station device that performs conversion between electrical signals and performs wireless communication using a radio frequency electrical signal with a mobile communication device. And
A base station apparatus comprising a function of the radio modem apparatus in addition to a base station function for performing radio communication with a mobile communication device using radio frequency electrical signals. An optical distributor that distributes an analog optical signal input via a downstream optical fiber cable from a conversion station that converts a radio frequency electrical signal and an analog optical signal, and outputs the signal to a plurality of terminal stations;
A plurality of photoelectric converters for converting analog optical signals input from the plurality of terminal stations via upstream optical fiber cables into radio frequency electrical signals, respectively;
A synthesizer for synthesizing radio frequency electrical signals output from the plurality of photoelectric converters;
A relay transmission station apparatus comprising: a photoelectric converter that converts the synthesized radio frequency electrical signal back into an analog optical signal and outputs the analog optical signal to the conversion station.

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