JPH088879A - Optical broadcasting system - Google Patents

Abstract

PURPOSE:To enjoy the advantages of optical communication by utilizing an electric communication channel by providing a bidirectional electric signal line between a network terminal interface and a user terminal, selecting a broadcasting channel through the line, performing conversion to electric signals and performing supply to the user terminal. CONSTITUTION:This system is provided with the optical broadcasting network access parts 161-16m of the network terminal interface where optical signals on which the broadcasting channel is multiplexed arrive from an optical communication network and the bidirectional electric signal line is provided between them and the remote reception terminals 2111-21mn of the user terminal. The access parts 161-16m are provided with control signal receivers 1911-19mn and selection control circuits 2011-20mn as means for selecting the broadcasting channel specified by selection control information supplied through the electric signal line, communication channel selection circuits 1711-17mn for converting the optical signals to the electric signals, information signal transmitters 1811-18mn for supplying the electric signals to the remote reception terminals 2111-21mn and information signal receivers 2211-22mn.

Description

Detailed Description of the Invention

[0001]

The present invention is used in optical communication. INDUSTRIAL APPLICABILITY The present invention is used in a system for performing multi-channel broadcasting via an optical communication network. The present invention relates to a technique for effectively using existing telecommunication lines in optical broadcasting.

[0002]

2. Description of the Related Art Optical fibers can simultaneously transmit light of various wavelengths to a long distance, but the bandwidth of light that can be transmitted by optical fibers is extremely wide. In order to effectively use the wide band of this optical fiber, a method of realizing a large number of communication channels by optical wavelength multiplexing or subcarrier multiplexing technology has been proposed. Optical wavelength multiplexing technology
This is a technique for simultaneously transmitting a plurality of optical signals having different wavelengths using an optical fiber. Subcarrier multiplexing technology is
This is a technique for realizing a plurality of communication channels by dividing the signal band capable of transmitting an optical signal of one wavelength on the frequency axis.

Here, a conventional example of a communication system using optical wavelength division multiplexing will be described with reference to FIG. FIG. 7 is an overall configuration diagram of a conventional communication system using optical wavelength division multiplexing. This communication system includes a plurality of transmitting terminals T _{1 to} T _n , a plurality of receiving terminals R _{1 to} R _n , an optical multiplexer M and an optical demultiplexer D. Each of the transmission terminals T _{1 to} T _n includes a light source that oscillates at a different wavelength, and converts an information signal to be transmitted into an optical signal and transmits the optical signal. The optical multiplexer M multiplexes the optical signals sent from all the transmission terminals T _{1 to} T _n and then sends them to the transmission line, and the optical demultiplexer D all the reception terminals R _{1 to} R.
This optical signal is distributed to _n . Each of the receiving terminals R _{1 to} R _n includes an optical filter capable of changing the wavelength of the transmitted light, can extract an optical signal of an arbitrary wavelength from the light input from the optical demultiplexer D, and finally can transmit the transmitting terminal. The information signals sent by T _{1 to} T _n can be received.

Next, a conventional example of a communication system using subcarrier multiplexing will be described with reference to FIG. FIG. 8 is an overall configuration diagram of a conventional communication system using subcarrier multiplexing. This communication system includes a plurality of transmission terminals t ₁
~ T _n , subcarrier transmitter S, and electro-optical converter E / O
And an optical demultiplexer D and a plurality of receiving terminals r _{1 to} r _n . First, the information signals sent from the plurality of transmitting terminals t _{1 to} t _n are input to the subcarrier transmitter S. The subcarrier transmitter S internally generates a high frequency electric signal called a subcarrier wave, and modulates the subcarrier wave with an information signal input from the outside to generate a signal for transmission. Is equipped with. The subcarrier transmitter S can simultaneously generate a plurality of subcarrier waves with different frequencies, and when a plurality of information signals are input from the outside, each information signal is used for modulation of different subcarrier waves. To be All the modulated subcarrier waves are combined and then output as an electric signal, and this electric signal is converted into an optical signal and output.
Optical demultiplexer D distributes the optical signal output from the subcarrier transmitter S to all receiving terminals r ₁ ~r _n. In the receiving terminal r ₁ ~r _n, first converts an optical signal inputted from the optical demultiplexer D into an electrical signal. Next, a subcarrier wave component having an arbitrary frequency is extracted from the electric signal, and an information signal modulating the subcarrier wave is extracted.

In both of the examples of the two communication systems described above, the principle that the information of each transmitting terminal is "broadcast" to all terminals and the receiver "selects" the appropriate information from the information. It realizes communication based on. A communication system based on such a communication principle is called a "broadcast selection type" communication system. An important parameter in the “broadcast selection” communication system is the number of feasible communication channels. Here, in a communication system using the optical wavelength multiplexing technique, the number of communication channels is determined by the number of wavelengths, and in a communication system using the subcarrier multiplexing technique, the number of communication channels is determined by the number of subcarriers. As a method of dividing the signal band of the optical signal, there is a time division multiplexing technique.

[0006]

The problem to be solved by the present invention is to realize an extremely large number of communication channels by combining the above-mentioned optical wavelength multiplexing technology with subcarrier multiplexing technology or time division multiplexing technology. It is an object of the present invention to solve the problem that occurs when the optical broadcasting communication system provided is considered and realized. First, a large-scale optical broadcast communication system will be described.

For example, it is considered that a very large number of communication channels can be realized by combining the wavelength multiplexing technique and the subcarrier multiplexing technique described above. That is,
When M optical signals of different wavelengths are sent to the optical fiber and N different communication channels are subcarrier-multiplexed on the optical signals of the respective wavelengths, the total number of communication channels is M.
XN. For example, if 100 communication channels are realized on one wavelength by subcarrier multiplexing using 100 wavelengths, a total of 10,000 communication channels can be realized. Furthermore, if 10 optical fibers are installed in parallel, 100,000 communication channels can be realized. When such a large number of communication channels can be realized, it becomes possible to allocate communication channels to each sender who uses the communication network. That is, all senders are allowed to occupy a particular communication channel, and the senders are free to send information on that communication channel. On the other hand, information of all communication channels is broadcast to all receivers, and by selecting and receiving any communication channel, it is possible to receive the information sent from any sender. In the following, a large-scale "broadcast selection type" communication system using a large number of communication channels thus realized on a large number of optical fibers is called an optical broadcast system.

However, when actually implementing the optical broadcasting system having such excellent characteristics, there are the following problems. First, there is a problem that the receiving terminal needs to be directly connected to the optical fiber forming the optical wiring section. In the above-mentioned optical broadcasting system, since the receiving terminal selects a specific communication channel from all the communication channels on the optical fiber, it is necessary to transmit information of all the communication channels to the receiving terminal. The large number of communication channels are realized by making full use of the wide band property of the optical fiber, and the connection between the receiving terminal and the optical fiber cannot be replaced by communication means such as wireless transmission or coaxial cable. This means that mobile receiving terminals using wireless transmission technology cannot be used. Furthermore, there is a constraint that the low-cost coaxial cable that has already been laid cannot be effectively used.

Secondly, in actually constructing the receiving terminal,
The problem is that the cost of optical components such as optical filters and photoelectric conversion is very high, and management is not easy. For example,
Optical filters require advanced control such as wavelength calibration in order to accurately extract only the optical signal of the required wavelength from the wavelength-multiplexed optical signal, which is an obstacle to cost reduction and size reduction. . In addition, optical component technology is advancing rapidly, and it is considered that the wavelength intervals that can be stabilized, the wavelength intervals that can be separated, the wavelength selection speed, etc. will change greatly in the future. However, when the optical components are individually provided to the receiving terminals, it is not easy to replace them with the new-generation optical components. This leads to the problem that it is difficult to put the optical broadcasting system into practical use while the optical component technology is immature.

Thirdly, there is a security problem in the optical broadcasting system. In the optical broadcasting system as described above, the receiving terminal can select all communication channels,
This gives the receiving terminal the possibility of eavesdropping on the communication of another person. Although the sending terminal will take measures such as encryption in consideration that the communication will be eavesdropped by others, there is a possibility of breakthrough in decryption technology and theft of the encryption key, which is a security concern. Exists.

The present invention has been made against such a background, and it is an object of the present invention to provide an optical broadcasting system in which a receiving terminal can be used by a coaxial cable or a wireless line while taking advantage of the advantages of optical communication. To aim. It is an object of the present invention to provide an optical broadcasting system capable of realizing an economical hardware configuration by sharing a device having an expensive optical component with a plurality of user terminals. An object of the present invention is to provide an optical broadcasting system capable of further improving confidential communication performance because the communication carrier can have a confidential communication function.

[0012]

[Means for Solving the Problems] The function of a receiving terminal is realized by a cooperative operation of an optical broadcasting network access unit and a remote receiving terminal. That is, the communication channel selecting means is provided outside the receiving terminal, and the communication channel selecting means provided outside the receiving terminal can be controlled from the receiving terminal. First, a communication channel selecting means directly connected to the optical demultiplexer is installed as an optical broadcasting network access unit, and a communication means for sending the information selected by the communication channel selecting means to the remote receiving terminal is added. The remote receiving terminal includes means for receiving the information signal sent from the optical broadcasting network access unit. Further, in order to maintain the usage mode in which the receiving terminal freely selects an arbitrary channel from a large number of communication channels on the optical fiber, the remote receiving terminal is provided with means for controlling the communication channel selecting means of the optical broadcasting network access unit. give. Specifically, a communication means for transmitting a signal for controlling the communication channel selection to the optical broadcast network access unit is added to the remote receiving terminal. A means for receiving the control signal and controlling the communication channel selecting means is added to the optical broadcasting network access section. Also, to limit the communication channels that can be selected by the receiver, the receiver recognizes the receiver from the control signal sent from the remote receiving terminal, and the communication channels other than the communication channels permitted to be received according to the receiver. The optical broadcasting network access unit will be provided with a control means for performing control so that is not selected.

That is, the present invention is an optical broadcasting system, and is characterized in that it is provided with a network terminal interface from which an optical signal multiplexed with a large number of broadcast channels comes from an optical communication network, and the network terminal interface and utilization A two-way electrical signal line is provided between the user terminal and the network terminal interface, and means for selecting the broadcast channel designated by the selection control information given via this electrical signal line and selected. And a means for converting the optical signal of the broadcast channel into an electric signal and a means for supplying the electric signal to the user terminal via the electric signal line.

As a result, the advantages of optical communication can be enjoyed while effectively utilizing the existing telecommunication line.

It is desirable that one network terminal interface be provided for a plurality of user terminals.

As a result, a plurality of user terminals can share an apparatus composed of a large number of expensive optical components, so that economical operation can be performed.

The electric signal line is preferably a wire line. Alternatively, the electric signal line may be a wireless line.

It is desirable that the means for selecting includes a table of broadcast channels corresponding to the user terminals and a means for prohibiting the selection of the corresponding broadcast channels for the user terminals recorded in the table. .

As a result, the confidential communication function can be provided to the receiving terminal user as a service on the communication network side.

[0020]

A communication means using an electric signal is provided between the means for selecting a specific communication channel from a plurality of communication channels included in the optical signal and the means for inputting selection control information and the means for outputting received information to the selecting means. Insert.

The selecting means is directly connected to the optical transmission line and has a function of selecting a specific communication channel from a large number of communication channels by using the advantage of the wide band optical signal. The input means and the output means are provided in separate boxes from the selecting means and communicate with each other by electric signals. As a result, it is possible to perform communication that takes advantage of the optical communication system while using the low-cost telecommunication system and telecommunication line.

The communication by electric signals may be performed by a wired line or a wireless line.

Further, when a plurality of receiving terminals are provided and the optical transmission lines are branched and connected to the selecting means of the receiving terminals, their identifiers are predetermined for the plurality of receiving terminals, and the identifiers are associated with each other. It is also possible to store in advance communication channels whose selection is prohibited.

As a result, the confidential communication function can be provided to the receiving terminal user as a service on the communication network side.

When the function of the receiving terminal is separated into the remote receiving terminal and the optical broadcasting network access section as described above, the communication channel selecting means provided from the remote receiving terminal to the optical broadcasting network access section is used by using the communication means. It is possible to directly control, and it becomes possible for the remote receiving terminal to receive the information on the communication channel selected by the communication channel selecting means using the communication means. This makes it possible to realize a situation equivalent to the case where the remote receiving terminal is directly connected to the optical fiber of the optical distribution section and controls the communication channel selecting means to receive information of an arbitrary communication channel. Means that. Moreover, the amount of information required between the optical broadcasting type access unit and the remote receiving terminal is about the information signal on the selected one communication channel and the control information for controlling the communication channel selecting means, and the number of communication channels is large. It can be easily realized by a simple communication means that does not have a band as wide as that of an optical fiber that realizes.

The present invention relates to an optical broadcasting type communication system realized by effectively utilizing a wide band of an optical fiber. In an optical broadcasting communication system, it is possible to realize a large number of communication channels by using a wide band of an optical fiber, and it is possible to distribute all information transmitted by a large number of transmitting terminals to receiving terminals. . The receiving terminal can receive information sent from an arbitrary transmitting terminal by selecting an arbitrary communication channel from the connected optical fibers. The present invention, by disposing the communication channel selecting means, which is premised to be provided inside the receiving terminal, outside the receiving terminal, and by providing the communication means for controlling the external communication channel selecting means from the receiving terminal, The receiving terminal that is not directly connected to the optical fiber can enjoy the same communication service as when it is directly connected to the optical fiber. The purpose is to reduce the cost of the receiving terminal, the cost of the subscriber line,
It is to realize protection of security in a broadcast communication system, sharing of costly communication channel selection means, and the like.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of the first embodiment of the present invention.

The present invention is an optical broadcasting system, and is characterized in that optical broadcasting network access units 16 _{1 to} 16 16 as network terminal interfaces from which optical signals multiplexed with a large number of broadcasting channels come from an optical communication network. comprising a _m, bidirectional electric signal line is provided between the remote receiving terminal 21 ₁₁ through 21 _mn as a user terminal and the optical broadcast network access unit 16 ₁ ~ 16 _m, the optical broadcast network access unit 16 _{1 to} 16 _m are control signal transmitters 25 _{11 to} 25 _mn and control signal receiver 19 ₁₁ as means for selecting a broadcast channel designated by the selection control information given via this electric signal line.
~ 19 _mn , communication channel selection control circuit 20 ₁₁ ~ 20
_mn and communication channel selection circuits 17 _{11 to} 17 as means for converting an optical signal of the selected broadcast channel into an electric signal
_mn , information signal transmitters 18 ₁₁ to 18 _mn and information signal receivers 22 _{11 to} 22 _mn as means for giving the electric signals to the remote receiving terminals 21 _{11 to} 21 _mn via the electric signal line. It is in.

The optical broadcasting network access units 16 _{1 to} 16 _m are provided for each of the plurality of remote receiving terminals 21 _{11 to} 21 _mn .

FIG. 1 shows the configuration of an optical broadcasting system in which m different wavelengths and n subcarrier signals on each wavelength are multiplexed. Information from m × n transmitting terminals is represented by signal lines 11 _{11 to} 11 _mn . Each of the subcarrier multiplexers 12 _{1 to} 12 _m multiplexes n pieces of the transmission information and outputs them as electric signals. The electric signals output from the respective subcarrier multiplexers 12 _{1 to} 12 _m are electric signal-optical signal converters 13 _{1 to} 13
It is converted into an optical signal by _m and output. Here, the electrical signal-optical signal converters 13 _{1 to} 13 _m output optical signals of different wavelengths. The optical signals output from the electric signal-optical signal converters 13 _{1 to} 13 _m are combined by the optical combiner 14 and transmitted to the optical demultiplexer 15 ₀ by the optical fiber cable. The optical demultiplexer 15 _0, an optical multiplexer 14
The optical signals multiplexed by the m optical broadcasting network access units 16 ₁ to 1
Divide into 6 _m . That is, optical signals of all wavelengths are transmitted to any of the m optical broadcasting type access units. The optical broadcasting network access units 16 _{1 to} 16 _m are respectively
N remote receiving terminals are connected, and a communication means exists between them.

[0031] One of the optical broadcast network access unit 16 ₁ includes an optical demultiplexer 15 ₁ for distributing an optical signal inputted from the optical demultiplexer 15 ₀ to n optical signals, from the outside from the optical signal transmitting a communication channel selection circuit 17 ₁₁ to 17 _1n to select designated communication channel for outputting information signal on the communication channel, the output of the communication channel selection circuit 17 ₁₁ to 17 _1n the remote receiving terminal 21 ₁₁ through 21 _1n Information signal transmitter 18 ₁₁ to 18
_1n and control signal receivers 19 _{11 to} 19 _1n for receiving the communication channel selection circuit control signal sent from the remote receiving terminal,
Based on the received control signal and a communication channel selection control circuit 20 ₁₁ to 20 _1n to control communication channel selection circuit. Other optical broadcasting network access units 16 _{2 to} 16
_m has the same configuration. One remote receiving terminal 21 ₁₁ is
An information signal receiver 22 ₁₁ that receives a signal transmitted from an information signal transmitter 18 _{11 of an} optical broadcasting access unit and outputs reception information to a signal line 23 ₁₁ , and a communication channel control input from the outside through a signal line 24 _11. Optical fiber network access unit 1
6 ₁ and a control signal transmitter 25 ₁₁ . The other remote receiving terminals 21 _{12 to} 21 _mn have the same configuration.

Optical broadcasting network access units 16 _{1 to} 16 _{m are described below.}
The cooperative operation of the remote receiving terminals 21 _{11 to} 21 _mn will be described.
A user using the remote receiving terminal 21 ₁₁ first inputs a communication channel identification number designating a communication channel to be received through the signal line 24 ₁₁ . This number is transmitted from the control signal transmitter 25 ₁₁ . Optical broadcasting network access unit 16
The control signal receiver 19 ₁₁ of ₁ receives the communication channel identification number sent from the remote receiving terminal and transmits this number to the communication channel selection control circuit 20 ₁₁ . The communication channel selection control circuit 20 ₁₁ controls the communication channel selection control circuit 20 ₁₁ to output only the information of the communication channel specified by the identification number from the optical signal input from the optical demultiplexer 15 _1. , And controls the communication channel selection circuit 17 ₁₁ . The output of the communication channel selection circuit 17 ₁₁ is the information signal transmitter 18
₁₁ , which is received by the information signal receiver 22 ₁₁ of the remote receiving terminal 21 ₁₁ . Information received is signal line 2
It is output to 3 ₁₁ . By such an operation, the user of the remote receiving terminal 21 ₁₁ can selectively receive the information on any communication channel.

Next, a concrete example of the communication channel selection circuit 17 ₁₁ and the communication channel selection control circuit 20 ₁₁ is shown in FIG. FIG. 2 shows a communication channel selection control circuit 20 according to the first embodiment of the present invention.
_{11 is} a block configuration diagram of _11. FIG. Communication channel selection circuit 17
_11, the transmission wavelength tunable filter 61 and the optical signal - consists electrical signal converter 62 and subcarrier receiver 63 are connected by a signal line 65 and 66 to the communication channel selection control circuit 20 _11.

The communication channel selection circuit 17 ₁₁ will be described below.
The operation of the communication channel selection control circuit 20 ₁₁ will be described.
First, an optical signal including a signal of a communication channel to be selected from the external optical demultiplexer 15 ₁ is input from the signal line 60. The variable transmission wavelength filter 61 transmits only the optical signal of the specified wavelength from the optical signal through the signal line 65, and transmits the optical signal to the electrical signal converter 62. Optical signal −
The electric signal converter 62 converts the transmitted optical signal into an electric signal and transmits it to the subcarrier receiver 63. The subcarrier receiver 63 receives only the information signal on the subcarrier wave having the designated frequency from the input electric signal through the signal line 66 and outputs it to the signal line 64.
Here, the wavelength of the optical signal to be selected, the frequency of the subcarrier wave to be selected, it is input from the communication channel selection control circuit 20 _11. Communication channel selection control circuit 2 shown in FIG.
In the example of 0 ₁₁ , the communication channel number to be selected is input from the outside through the signal line 67. The communication channel selection control circuit 20 ₁₁ internally stores the relationship between the communication channel number and the optical wavelength or subcarrier frequency. When the communication channel number is input from the outside, the corresponding optical wavelength is sent to the signal line 65. , The corresponding subcarrier frequency is signal 66
Are output respectively. In this way, by using the communication channel selection circuit 17 ₁₁ and the communication channel selection control circuit 20 ₁₁ shown in FIG. 2, an information signal on an arbitrary communication channel is extracted from the optical signals input from the outside. The operation of outputting can be realized.

In the optical broadcasting system as described above, when the communication channel is fixed for each information sender and the user of the sender remote receiving terminal knows in advance the communication channel number of the information sender who wants to receive. Communication is easily realized by inputting the communication channel number to be selected from the remote receiving terminal, transmitting this to the optical broadcasting network access unit, and having the remote receiving terminal transmit the information signal on that communication channel. be able to.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram of the communication channel selection circuits 17 _{11 to} 17 _{mn according to} the second embodiment of the present invention. The operation will be described when the correspondence between the information sender and the communication channel number changes with time, or when it is not known which information sender is transmitting the information to be received at each time point. In such a case, the receiver needs a means to discover the communication channel that actually sends the information to be received from the communication channels that may send the information to be received. Become. Therefore, as a method capable of coping with such a case, a method will be considered in which the information sender includes a means for transmitting a signal for identifying the receiver to the information signal on each communication channel. If such an identification signal is transmitted on the communication channel, the receiver receives the communication channels that may be received in sequence, and if the specific identification signal is transmitted on a certain communication channel,
It can be determined that the communication channel should be received and otherwise not required. In the following, specifically, it is assumed that the sender adds a specific identification number to the information signal for transmission.

FIG. 3 shows an embodiment of the remote receiving terminal 21 ₁₁ using such a communication system. The remote receiving terminal 21 ₁₁ shown in FIG. 3 includes an information signal receiver 28, an identification number recognizer 30, an identification number memory 32, an identification number comparator 33, a communication channel sweeper 34, and a control signal transmitter 35. Composed.

The operation of the remote receiving terminal 21 ₁₁ of FIG. 3 will be described below. First, the communication channel sweeper 34 stores in advance a large number of communication channels that the remote receiving terminal 21 ₁₁ may receive. An identification number for designating a communication channel to be received by the remote receiving terminal 21 ₁₁ is stored in advance in the identification number memory 32 from the outside through the signal line 31. The identification number memory 32 can store a plurality of identification numbers.

Here, it is assumed that the communication channel to be received by the remote receiving terminal 21 ₁₁ is not fixed. At this time, the communication channel sweeper 34 selects one communication channel from the stored communication channels and outputs a control signal for selecting the communication channel. The control signal transmitter 35 transmits the control signal output from the communication channel sweeper 34 to the optical broadcasting network access unit through the signal line 36. The optical broadcasting network access unit is a remote receiving terminal 21 ₁₁
The designated communication channel is selected based on the control signal sent from the device, and the information signal on the selected communication channel is transmitted to the remote receiving terminal 21 ₁₁ . Information signal receiver 28
Receives the information signal transmitted from the optical broadcasting network access unit through the signal line 27. The received information signal is signal line 2
9 is output. Here, when the sender is transmitting the identification information, the information signal on the signal line 29 also includes the identification number.

The identification number recognizer 30 detects, recognizes and outputs this identification number from the received information signal. The identification number comparator 33 determines whether the identification number output from the identification number recognizer 30 matches any of the identification numbers stored in the identification number memory 32, and outputs it. While the output of the identification number comparator 33 indicates that the identification numbers do not match, the communication channel sweeper 34 sequentially selects the communication channels from the stored communication channels, and outputs control information for designating the communication channels. The operation of sending is repeated. On the other hand, when the output of the identification number comparator 33 indicates that the identification numbers match, the communication channel sweeper 34 maintains the state in which the communication channel currently selected is still selected. This state continues until the reception of the communication channel is completed or an instruction to interrupt the reception is given from the outside. When this state ends, the communication channel sweeper 34 again starts the operation of repeating the communication channel selection.

By the operation as described above, the remote receiving terminal 2
₁₁ receives the information signal on the communication channel which is transmitting the identification number stored in the identification number memory 32 at each time from a large number of communication channels which may be received, and the signal line 29 can be output. Also,
Only when the output of the identification number comparator 33 is monitored and the output of the identification number comparator 33 indicates that the identification numbers match,
The information signal output to the signal line 29 can also be determined as valid information.

Such an operation is performed in the optical broadcasting system.
It can also be used when the sender calls a specific recipient. First, a different recipient identification number is assigned to each recipient, and the sender is notified of the recipient identification number. The recipient stores his or her recipient identification number in the identification number memory of the remote receiving terminal used at that time. Here, when the sender transmits the identification number of the recipient who wants to call on the communication channel as the transmission information, the remote receiving terminal 21 ₁₁ can correctly receive this communication channel by the above operation. Therefore, if the receiver monitors the signal of the identification number comparator of the remote receiving terminal 21 ₁₁ , the call from the sender can be detected. Here, regardless of which communication channel is used by the sender and which remote receiving terminal 21 ₁₁ is used by the receiver, the above-described calling is performed. That is, it is not necessary to specifically specify the actual communication channel used by the sender or the remote receiving terminal 21 ₁₁ used by the receiver.

Next, a means for sequentially checking the identification numbers on the information signals on the communication channels as shown in FIG. 3 and selecting the communication channel transmitting the specific identification number,
Not the remote receiving terminal 21 ₁₁ , but the optical broadcasting network access unit 16
FIG. 4 shows an example of arrangement in _one communication channel selection control unit 20 ₁₁ as a third embodiment of the present invention. FIG. 4 is a block diagram of the communication channel selection circuit 17 ₁₁ and the communication channel selection control circuit 20 ₁₁ of the third embodiment of the present invention. In FIG. 4, an optical signal is input to the communication channel selection circuit 81 from the outside, and an information signal on the communication channel selected by the communication channel selection circuit 17 ₁₁ is output to the signal line 85. The information signal on the signal line 85 is transmitted to the remote receiving terminal 21 ₁₁ through the information signal transmitter 86. Here, the information signal transmitter 86 is controlled by the output of the identification number comparator 92. Control information receiver 87, from the control signal sent from the remote receiving terminal 21 _11, receives the identification number to the recipient is selected, and inputs the communication channel selection control circuit 20 _11. The communication channel selection control circuit 20 _11, an identification number memory 90, an identification number recognizer 91, the identification number comparing circuit 92
And a communication channel sweeper 93 and a communication channel compatible memory 89.

Below, the communication channel selection control circuit 20 ₁₁
The operation of will be described. First, the identification number input from the control signal receiver 87 is stored in the identification number memory 90.
The information signal transmitter 86 is in a state of not transmitting the signal on the signal line 85 to the remote receiving terminal. Next, the communication channel sweeper 93 selects and outputs one communication channel number from a large number of communication channel numbers stored in advance. The communication channel correspondence memory 89 controls the communication channel selection circuit so that the information signal of the communication channel corresponding to the communication channel number is output to the signal line 85. When the information signal of the communication channel designated by the communication channel sweeper 93 is output to the signal line 85, the identification number recognizer 91 recognizes and outputs the identification number sent by the sender from the information signal. The identification number comparator 92 uses the identification number memory 9
Among the identification numbers stored in 0, it is determined whether or not there is one that matches the output of the identification number recognizer 91, and the result is output. Here, if there is no matching identification number, the communication channel sweeper 93 outputs the next communication channel number. The information signal transmitter 86 maintains a state in which no information is transmitted.
However, if any of the identification numbers stored in the identification number memory 90 matches the output of the identification number recognizer 91, the communication channel sweeper 93 maintains the selection of the communication channel. The information signal transmitter 86 transmits the information signal on the signal line 85 to the remote receiving terminal.

By such an operation, the remote receiving terminal 21
_When the optical broadcast network access unit 16 ₁₁ transmits the identification number on the communication channel to be received as a control signal to the optical broadcast network access unit 16 ₁₁ , the optical broadcast network access unit 16 ₁₁ individually inspects a large number of communication channels and determines the desired identification number. When the communication channel being transmitted is detected, the operation of transmitting the information signal on the communication channel to the remote receiving terminal can be realized.

Optical broadcast network access unit 16 in the present invention₁
~ 16_mAnd remote receiving terminal 21₁₁~ 21_mnCommunication between
As a means for realizing it, the optical broadcast network access unit 16 is fixedly provided.
₁~ 16_mAnd remote receiving terminal 21₁₁~ 21_mnConnect with
Not the remote receiving terminal 21₁₁~ 21_mnCommunication from
In response to the initial request, the optical broadcasting network access unit 16₁~ 16_m When
Remote receiving terminal 21₁₁~ 21_mnUsing the means to connect
An example will be described. FIG. 5 shows the optical broadcasting network access unit 43.₁~
43_mAnd a mobile terminal 51 as a remote receiving terminal₁~ 51_q
This is an example of realizing the communication with
It is shown as a fourth embodiment of the invention. FIG. 5 shows the present invention
It is a whole block diagram of 4th Example. This is m optical broadcasting
Network access unit 43₁~ 43_mAnd q mobile terminals 51₁
~ 51_qIn the example where and are connected by wireless communication method
is there. Here, the mobile terminal 51₁~ 51_qIs the remote of the present invention
In addition to the function of the receiving terminal,
Yes, optical broadcasting network access unit 43₁~ 43_mAlso send function
I have it. Optical broadcasting network access unit 43₁~ 43_mAnd remote
Mobile terminal 51 as communication terminal₁~ 51_qFixed between
Connection relationship does not exist, the mobile terminal 51₁~ 51_qIs self
Its location can be changed for any reason, and if necessary, the neighborhood
Optical broadcasting network access unit 43₁~ 43_mConnection with
You can

The optical broadcasting network access units 43 ₁ to 43 _m include subcarrier multiplexers 46 _{1 to} 46 _m , electrical signal-optical signal converters 44 _{1 to} 44 _m , and optical demultiplexers 45 _{1 to} 45 _m.
and _m, a communication channel selection circuit 17 ₁₁ to 17 _mn, and a communication channel selection control circuit 20 ₁₁ to 20 _mn, radios 49
_1-49 and _m, composed of a radio communication control unit 50 ₁ to 50 _m. Here, m electrical signal-optical signal converters 44
It is assumed that the wavelengths of the optical signals output from the respective _{1 to} 44 _m are different.

The mobile terminals 51 _{1 to} 51 _q include mobile radio communication devices 52 _{1 to} 52 _m and mobile radio communication controllers 53 _{1 to} 53.
It consists of _q and. Also, each mobile terminal 51 ₁
˜51 _q are signal lines 54 _{1 to} 54 _q for inputting transmission information.
, Signal lines 55 _{1 to} 55 _q for outputting reception information, and signal lines 56 _{1 to} 56 _q for inputting information for controlling a communication channel to be received.

The optical multiplexer 40 multiplexes the optical signals sent from the _m optical broadcasting network access units 43 ₁ to 43 _m and inputs them to the optical fiber cable OF. The optical demultiplexer 42
Is for distributing an optical signal on the optical fiber cable OF to m optical broadcasting access units 43 ₁ to 43 _m .

The operation of the optical broadcasting system shown in FIG. 5 will be described below. First, the respective optical broadcast network access units 43 ₁ to 43
_{In m} , one signal line for inputting the information signal to be multiplexed by the subcarrier multiplexers 46 _{1 to} 46 _m , one signal line for outputting the information signal from the communication channel selection circuits 17 _{11 to} 17 _mn , and communication One signal line for inputting a control signal to the channel selection control circuits 20 _{11 to} 20 _mn is grouped together, and one optical broadcasting network access unit 43 ₁ to 43.
There are n signal line groups # 1 to #n in _m . Optical broadcasting network access units 43 ₁ to 43 _m wireless communication devices 49 ₁ to 49 _m
m represents each signal line group by one mobile terminal 5
The operation of connecting to the signal lines of 1 _{1 to} 51 _q is performed. Therefore, a maximum of n mobile terminals 51 _{1 to} 51 _n can be simultaneously connected to one optical broadcasting network access unit 43 ₁ to 43 _m .

The wireless communication controller 50 ₁ to 50 _m of the optical broadcast network access unit 43 ₁ ~ 43 _m, the mobile terminal 51 ₁ to 51 _q
Manages signal line groups that are not connected to the mobile wireless communication devices 52 _{1 to} 52 _q of the mobile terminals 51 _{1 to} 51 _q.
Waiting to receive a signal from. When the mobile terminals 51 _{1 to} 51 _q start communication, the mobile radio communication controllers 53 _{1 to} 53 _{q first} set the mobile terminals 51 _{1 to} 53 _q.
Connection request signals are output to the optical broadcasting network access units 43 ₁ to 43 _m near _{1 to} 51 _q through the mobile radio communication devices 52 _{1 to} 52 _q . One optical broadcasting network access unit 43 ₁ ~
43 In _m, radios 49 ₁ to 49 _m is, the mobile terminal 5
When the connection request signal transmitted from 1 _{1 to} 51 _q is received, this is transmitted to the wireless communication controllers 50 ₁ to 50 _m . The wireless communication controllers 50 ₁ to 50 _m select one signal line group #c when there is one among the signal line groups that is not connected to the mobile terminals 51 _{1 to} 51 _{q at} that time, and performs wireless communication. through bowl 49 ₁ to 49 _m, the mobile terminal 5
Notify that _{1 to} 51- _q can be connected. Mobile radio communication controllers 53 _{1 to} 53 of the mobile terminals 51 _{1 to} 51 _{q
When q} confirms that connection is possible from the optical broadcasting network access units 43 ₁ to 43 _m , the mobile radio communication devices 52 _{1 to} 52 m
Output the communication start signal through _q . Light broadcast network access unit 43 ₁ ~ 43 _m is, when receiving the communication start signal transmitted from the mobile terminal 51 ₁ to 51 _q, the previous signal line group, the connection signal lines of the mobile terminal 51 ₁ to 51 _q Will be realized. That is, the signal lines 54 _{1 of the} mobile terminals 51 _{1 to} 51 _q
-54 _q, the transmission information signals input from the sub-carrier multiplexers 46 ₁ to 4 of the optical broadcasting network access units 43 ₁ to 43 _m.
Input to 6 _m , communication channel selection circuit 17 _{11 to} 17 _mn
Is output to the signal lines 55 _{1 to} 55 _q , and the signal line 56
Connection of _1-56 control information signal inputted from the _q are input to the communication channel selection control circuit 20 ₁₁ to 20 _mn are established.

After the plurality of mobile terminals 51 _{1 to} 51 _q are connected to the optical broadcasting network access units 43 ₁ to 43 _m by the above-described operation, the optical signals of the first embodiment of the present invention shown in FIG. Each mobile terminal 51 is operated by the same operation as the broadcasting system.
Communication between _{1 and} 51 _q can be realized. That is, the transmission information transmitted from one of the mobile terminals 51 _{1 to} 51 _{q is} transmitted to the other mobile terminals 51 _{1 to} 51 _q by the subcarrier multiplexers 46 _{1 to} 46 _m of the optical broadcasting network access units 43 ₁ to 43 _m.
It is combined as an electric signal together with the transmission information sent from. The combined electric signal is an electric signal-optical signal converter 44.
It is converted into an optical signal by _{1 to} 44 _m and output. The optical signals output from the _m optical broadcasting network access units 43 ₁ to 43 _m and having different wavelengths are multiplexed by the optical multiplexer 40 and then demultiplexed by the optical demultiplexer 42. Is transmitted to the optical broadcasting network access units 43 ₁ to 43 _m .

Optical broadcasting network access units 43 ₁ to 4
At 3 _m , the optical signal is further branched by the optical demultiplexers 45 _{1 to} 45 _m , each of which has n communication channel selection circuits 17
It is transmitted to the _{11 ~17 mn.} Each of the n communication channel selection circuits 17 _{11 to} 17 _mn extracts an information signal on a specific communication channel from the optical signal. The extracted information signal is transmitted to the mobile terminals 51 _{1 to} 51 _q connected to the respective communication channel selection circuits 17 _{11 to} 17 _mn through the wireless communication devices 49 ₁ to 49 _m . In addition, the mobile terminal 51 ₁
Control signals transmitted from the mobile terminals 51 ₁ to 51 _{q are} transmitted to the communication channel selection circuits 17 _{11 to} 17 _mn.
51 _q can specify the communication channel from which the information signal is to be taken out. By such operation, in the optical broadcasting system shown in FIG. 5, any mobile terminal 51 _{1 to} 51 ₁
Users who use _q can communicate with each other.

In the above system, the mobile terminal 51 ₁
In to 51 _q, sender changing the position in connection with one of the optical broadcast network access unit 43 ₁ ~ 43 _m, the mobile terminal 51 ₁ to 51 _q and optical broadcasting network access unit of 43 ₁ ~ 43 _m If the distance between them becomes long, wireless communication may become difficult. If there are a sufficient number of optical broadcasting network access units 43 ₁ to 43 _m , in such a situation the mobile terminal 51 ₁
~ 51 _q can be newly connected to a communication channel by connecting to another optical broadcasting network access unit 43 ₁ to 43 _m ,
Communication can be continued. At this time, the optical wavelength and the subcarrier frequency of the communication channel used by the sender change. Therefore, in order for the receiver to realize communication with a predetermined sender at any time, it is necessary to use a means for identifying the sender. An example will be described below.

First, a number for identifying each sender will be given. At the time of communication, the sender adds the identification number to the information signal and transmits it. The mobile terminal 51 ₁ to 51 _q is in that it comprises means for comparing the identification number included in the information signal while sweeping the communication channel as shown in FIG. The receiver stores the sender identification number of the sender he / she wants to receive in the identification information memory as if the sender knows the sender identification number. Then, by the operation described in FIG. 3, the information signal on the communication channel which is transmitting the sender identification number specified in the information signal is selected from the communication channels being transmitted at that time, and the information signal is transmitted to the receiver. To be Alternatively, as shown in FIG. 4, the communication channel selection control circuits 20 ₁₁ to 20 _m of the optical broadcasting network access units 16 _{1 to} 16 _m are connected.
It is also possible to receive the communication channel corresponding to the sender as described above by providing 20 _mn with means for comparing the identification number included in the information signal while sweeping the communication channel. At this time, the receiver uses the sender identification number of the sender who wants to receive the control information as the optical broadcast network access unit 16
_When transmitted to _{1 to} 16 _m , the optical broadcasting network access unit 16 ₁ to
It is possible to realize an operation in which the 16 _m sequentially inspects a large number of communication channels and sends the information signal on the communication channel which transmits the identification number designated by the receiver to the remote receiving terminals 21 _{11 to} 21 _mn . Thus, if the sender identification number is added to the information signal, the receiver can detect a new information channel that the sender has started to use and can continue communication.

Next, as an embodiment of the communication channel selection control circuit 20 _11, an example of a remote receiving terminal 21 ₁₁ communication channel selection control circuit 20 ₁₁ which includes means for limiting the received possible communication channels in accordance with the user's FIG. 6 shows a fifth embodiment of the present invention. 6 is a block diagram of a communication channel selection control circuit 20 ₁₁ of the present invention the fifth embodiment. The communication channel selection control circuit 20 ₁₁ has a communication channel compatible memory 73.
A signal line 76 for inputting a control signal sent from a remote terminal, which is composed of a receiver compatible memory 74 and a receiver compatible controller 75, and outputs the optical wavelength and subcarrier frequency of the selected communication channel, respectively. The signal lines 70 and 71 are provided. The communication channel corresponding memory 73 stores the optical wavelength and the subcarrier frequency corresponding to each communication channel. The receiver correspondence memory 74 stores a receiver identification number set and a communication channel number set corresponding to the set.

First, it is assumed that a recipient identification number is assigned to each recipient. When the receiver wants to receive a specific communication channel, the remote receiving terminal transmits the receiver identification number and the communication channel number to be received to the optical broadcast network access unit as a control signal. In the optical broadcasting network access unit, the control signal from the remote receiving terminal is input to the receiver corresponding controller 75 through the signal line 76. When the control signal is input, the receiver-corresponding controller 75 firstly checks whether or not each of the receiver identification number sets in the receiver-corresponding memory includes the input receiver identification number.

If the input recipient identification number is not included in the stored recipient identification number set, the recipient correspondence controller does not correspond to any communication channel that actually exists. Such light wavelength and subcarrier frequency are output to the signal lines 70 and 71, respectively. The communication channel selection circuit, which is controlled based on the outputs of the signal lines 70 and 71, does not extract any information from the input optical signal, so that the receiver using the remote receiving terminal receives no information signal. I can't tell.

If the input recipient identification number is included in one recipient identification number set stored in the recipient correspondence memory 74, the receiver correspondence controller 75
Checks whether the communication channel number set corresponding to the receiver identification number set includes the communication channel number input as the control signal.

If the input communication channel number is not included in the stored communication channel number set, the receiver-corresponding controller 75 causes the receiver identification number to correspond to any receiver identification number. Similarly to the case where the optical wavelength and the subcarrier frequency are not included, the optical wavelength and the subcarrier frequency that do not correspond to any actually existing communication channels are output to the signal lines 70 and 71, respectively.

If the input communication channel number is included in the stored communication channel number set, the receiver corresponding controller 75 refers to the communication channel corresponding memory 73 and is input. The optical wavelength and the subcarrier frequency corresponding to the communication channel number are output to each of the signal lines 70 and 71. By such an operation, it is possible to realize a limitation such that only a specific communication channel among the communication channels provided by the optical broadcast communication system can be received, depending on the recipient who uses the remote receiving terminal. It is possible.

In the above-described embodiment, a channel for constantly transmitting an information signal indicating the abnormality of the recipient identification number is provided in a specific communication channel among a large number of communication channels, and the input recipient identification number is received. Person correspondence memory 74
It is also conceivable to output a signal for controlling the communication channel selection circuit to the signal lines 70 and 71 so as to select this communication channel when the signal is not included in the recipient identification set stored in.

Further, among a large number of communication channels, a channel for constantly transmitting an information signal notifying the abnormality of the communication channel number is provided to a specific communication channel, and the input communication channel number becomes the receiver identification number. It is also possible to output a signal for controlling the communication channel selection circuit 17 ₁₁ to the signal lines 70 and 71 so as to select this communication channel when it is not included in the corresponding communication channel set.

As described above, in the present invention, when the user selects a communication channel to be received from a large number of communication channels, a means for actually selecting a specific communication channel from the optical fiber is provided in the user terminal. While arranging it outside
Since the receiver can control the external communication channel selection means, the following effects are expected.

First, when connecting the sender and the receiver,
No complicated control is required inside the communication network. For example, in a conventional routing-type communication network such as a public telephone network or an ATM network, in order to realize a communication line between a sender and a receiver, an empty line in the network is searched and the empty line is multistaged. Since a communication line between the sender and the receiver is realized by connecting, it is necessary to constantly manage the position information of the sender and the receiver and the information of the empty line in the entire network. It required complex control over the whole area. However, in the above-mentioned optical broadcasting type communication network, the sender is connected to one communication channel, and the receiver is connected to the communication channel selection means and the communication channel selection control means independently of this. No complicated control is required in the communication network except for local implementation between the network access unit and the remote receiving terminal and between the optical broadcast network access unit and the mobile terminal. Further, it is not necessary to manage information regarding the positions of senders and receivers. The control of the connection between the sender and the receiver is realized by the receiver directly controlling the external communication channel selection means. In the embodiment using the wireless communication system shown in FIG. 4, it is necessary to manage the use status of the signal line groups, but the optical broadcasting network access units independently manage the signal line groups locally. Good.

Second, the terminal used by the receiver need not be directly connected to the large capacity optical fiber transmitting information on a large number of communication channels. That is, a band for transmitting the information signal on the communication channel selected by the receiver and a control signal for controlling the communication channel selection are transmitted to the communication means connecting the optical broadcasting network access unit and the remote receiving terminal. It just needs bandwidth. Therefore, an inexpensive coaxial cable network, a wireless communication network, an optical fiber network with low multiplicity, etc. are used between the optical broadcasting network access unit and the remote receiving terminal according to the information signal required by the receiver. It is possible to install a receiving terminal according to various kinds of situations. In particular, when the connection between the remote receiving terminal and the optical broadcasting network access unit is realized by using the wireless communication network as shown in FIG.
The mobile terminals of the sender and the recipient can freely realize communication using the optical broadcast communication system from any point at any time.

Thirdly, if the cost of expensive optical components such as optical filters and photoelectric conversion is arranged outside the receiving terminal, the cost of each receiving terminal can be reduced. Further, if the information transmitting means for the communication channel, the communication channel selecting means, etc. are centrally arranged in the optical broadcasting network access section, it becomes possible for a larger number of users to jointly use them, and the whole communication system. Since it is possible to reduce the number of information transmitting means and communication channel selecting means necessary for the above, the cost can be reduced in the entire communication system. For example, in the embodiment shown in FIG. 4, each mobile terminal selects and uses the transmission means arranged in the optical broadcast network access unit and a large number of communication channel selection means that are not used at the start of communication. Is supposed to do. Therefore, the amount of equipment to be arranged in the optical broadcasting network access unit can be determined based on the number of mobile terminals that are likely to communicate at the same time, rather than the number of mobile terminals that actually exist.

Fourth, if the important parts for utilizing the communication channel are centrally arranged in the optical broadcasting network access section, the communication system operator can easily maintain the communication system. First, it is easy to replace a component for using the communication channel in the case of a failure or the like. Further, when changing the number of optical wavelengths or the number of subcarriers used in the optical broadcasting communication system, the subcarrier multiplexer and the communication channel selecting means can be easily replaced. When the communication channel selecting means is arranged inside the receiving terminal without using the present invention, it takes time and effort to collect the terminals from all users and replace optical parts or the like with each terminal.

Fifth, in the above-mentioned optical broadcasting communication system, sufficient security can be compensated. In a broadcast selection type communication network in which all information is transmitted to all receivers and the receiver selects the information to be received, there is a possibility that the receiver may receive information on communication channels that should not be received. is there. In consideration of this, the sender is supposed to use a means for increasing the confidentiality of communication, such as encryption, if necessary. However, the reliability of the secret story based on encryption is unclear because of the progress of the decryption technology and the possibility of the decryption key being stolen, and it cannot be said that sufficient security can be secured. However, for example, if the communication channel selection control means as shown in FIG. 5 is used, the receivable communication channels can be limited according to the user, so that the confidentiality stronger than the encryption can be achieved.

[0070]

As described above, according to the present invention,
While utilizing the advantages of optical communication, it is possible to realize an optical broadcasting system in which a receiving terminal can be used by a coaxial cable or a wireless line. According to the present invention, it is possible to realize an economical hardware configuration by sharing a device having an expensive optical component with a plurality of user terminals. According to the present invention, the confidential communication function can be provided on the telecommunications carrier side, so that the confidential communication performance can be further improved.

According to the present invention, by using a very large number of communication channels realized on an optical fiber, a large number of users can transmit information on the communication channels from anywhere, and
It is easy to realize that any user selects any communication channel and selects information. In the communication channel realized by the fusion of the optical wavelength multiplexing technology and the subcarrier multiplexing technology, both digital signals and analog signals can be transmitted on the communication channel.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a first embodiment of the present invention.

FIG. 2 is a block configuration diagram of a communication channel selection control circuit according to the first embodiment of the present invention.

FIG. 3 is a block configuration diagram of a communication channel selection circuit according to a second embodiment of the present invention.

FIG. 4 is a block configuration diagram of a communication channel selection circuit according to a third embodiment of the present invention.

FIG. 5 is an overall configuration diagram of a fourth embodiment of the present invention.

FIG. 6 is a block configuration diagram of a communication channel selection circuit according to a fifth embodiment of the present invention.

FIG. 7 is an overall configuration diagram of a communication system using optical wavelength multiplexing of a conventional example.

FIG. 8 is an overall configuration diagram of a communication system using subcarrier multiplexing of a conventional example.

[Explanation of symbols]

11 _{11 to} 11 _mn , 23 ₁₁ to 23 _mn , 24 _{11 to} 24 _mn , 5
_{4 1 ~54 q, 55 1 ~55} q, 56 1 ~56 q signal lines _{12 1 ~12 m, 46 1 ~46} m subcarrier multiplexer _{13 1 ~13 m, 44 1 ~44} m, E / O Electrical signal-
Optical signal converters 14, 40, M optical multiplexers 15 ₀ to 15 _m , 42, 45 _{1 to} 45 _m , D optical demultiplexers 16 _{1 to} 16 _m , 43 ₁ to 43 _m Optical broadcasting network access unit 17 ₁₁ ~ 17 _mn communication channel selecting circuit 18 ₁₁ ~18 _mn, 86 information signal transmitter 19 ₁₁ ~19 _mn, 87 control signal receiver 20 ₁₁ to 20 _mn communication channel selection control circuit 21 ₁₁ through 21 _mn remote receiving terminal 22 _{11-22 mn} , 28 information signal receiver 25 _{11 to} 25 _mn control signal transmitter 60 optical signal 61 transmission wavelength tunable filter 62 optical signal-electrical signal converter 63 subcarrier receiver 64 information signal 65 optical wavelength selection signal 66 subcarrier selection signal 67 communication channel signals 27, 29, 31, 36, 70, 71, 76, 80, 8
5, 96, 97 signal line 30, 91 identification number recognizer 32, 90 identification number memory 33, 92 identification number comparator 34, 93 communication channel sweeper 35 control signal transmitter 49 ₁ to 49 _m wireless communication device 50 ₁ to 50 _m wireless communication controller 51 _{1 to} 51 _q mobile terminal 52 _{1 to} 52 _q mobile wireless communication device 53 _{1 to} 53 _q mobile wireless communication controller 73, 89 communication channel compatible memory 74 receiver compatible memory 75 receiver compatible controller 94 communication channel designation signal _{R 1 ~R n, r 1 ~r} n receiving terminal S subcarrier transmitter _{T 1 ~T n, t 1 ~t} n transmitting terminal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04J 14/06 H04H 1/02 Z F

Claims (5)

[Claims] 1. A network terminal interface in which an optical signal multiplexed with a large number of broadcast channels comes from an optical communication network,
A bidirectional electric signal line is provided between the network terminal interface and the user terminal, and a broadcast channel designated by the selection control information given via this electric signal line is selected for this network terminal interface. Means for converting the optical signal of the selected broadcast channel into an electric signal, and means for giving the electric signal to the user terminal via the electric signal line. . 2. The optical broadcasting system according to claim 1, wherein one network terminal interface is provided for a plurality of user terminals. 3. The optical broadcasting system according to claim 1, wherein the electric signal line is a wired line. 4. The optical broadcasting system according to claim 1, wherein the electric signal line is a wireless line. 5. The selecting means includes a table of broadcast channels corresponding to the user terminals, and means for prohibiting the selection of the corresponding broadcast channels for the user terminals recorded in the table. The optical broadcasting system according to item 2.