JP2000261782A - Bidirectional optical CATV system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To make it possible to flexibly cope with the situation of a subscriber and the characteristics of an application, and to make it possible to cope with various uplink transmission systems at a subscriber's house by simple modification. SOLUTION: A CATV center 1 and a plurality of subscriber homes 2
A and 2B are connected directly or via the communication center 5 by optical fibers 9, 9A and 9B. And the subscriber premises 2
A and 2B each include a home device 3 for terminating a video signal and a downlink communication signal transmitted from the CATV center 1 and an uplink communication signal transmitted from a subscriber terminal in the subscriber's home.
The CATV center 1 transmits a video signal and a downlink communication signal, and a subscriber's house transmits an uplink communication signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-way optical CATV system for transmitting a video signal from a CATV station to a subscriber's home and performing communication between the CATV station and the subscriber's home.

[0002]

2. Description of the Related Art FIG. 16 shows a configuration example of a conventional bidirectional CATV system. Subscriber home 1 from CATV center 101
Coaxial cable 1 as the transmission path to 02A and 102B
03 is laid. An amplifying device 10 for compensating for a decrease in signal strength due to distribution and attenuation is provided on the coaxial cable 103.
4 may be installed, which basically has only the function of physically amplifying the signal.

When communication is performed in this configuration example, a downlink communication signal is modulated by a carrier wave, frequency-multiplexed with a video signal, and distributed to each subscriber similarly to the video signal. Then, each subscriber's home uses a device such as a cable modem (hereinafter, referred to as CM) or a digital set-top box (hereinafter, referred to as D-STB) to demodulate the modulated downstream communication signal.

[0004] The upstream communication signal is transmitted using the same coaxial cable as the downstream transmission (hereinafter referred to as RF return) or using an existing telephone network (hereinafter referred to as teleco return).
Is transmitted. In either case, the physical layer and the MAC layer are terminated in the CATV center, and the LA in the CATV center is terminated.
N.

[0005] Various control devices and service providing devices used in the interactive service receive uplink communication from the LAN and provide services. In the configuration example using only the coaxial cable as shown in FIG. 16, many subscribers are connected to one coaxial cable.

For this reason, noise from the terminals of the coaxial cable installed in each subscriber's home may flow in the CATV center, and may become as large as the upstream communication signal.
For this reason, in such a configuration example, an interactive service by teleco-return is performed.

[0007] On the other hand, as shown in FIG.
There is also a configuration example in which a coaxial cable is laid only in the vicinity of A and 102B. In this case, the video signal is converted from an electric signal to an optical signal by an optical transmitting / receiving device in the center of the CATV center,
It is sent to an optical fiber laid to the vicinity of the subscriber's house.

In the vicinity of the subscriber's house, the subscriber's optical transmission / reception device 1
07 is installed, and converts a video signal from an optical signal to an electric signal. From the subscriber side optical transceiver 107 to each subscriber's home 10
A coaxial cable 106 is laid to 2A and 102B, whereby the video signal is distributed to each subscriber.

In this configuration example, the subscriber side coaxial cable 106 is terminated by the subscriber side optical transceiver 107. Therefore, by limiting the number of subscribers accommodated in one subscriber-side optical transmission / reception apparatus, it is possible to reduce a signal noise that becomes an obstacle in the RF return.

[0010]

However, in such a conventional optical CATV system, in a multi-family house, the flow noise is large and the countermeasures are not easy compared to a single-family house. Cannot provide interactive services. For this reason, in order to provide an interactive service to all subscribers, it is necessary to mix the two methods of RF return and teleco return.

[0011] This means that it is necessary to prepare both a communication modem having a demodulation function for upstream communication and a telephone line terminating device for terminating upstream transmission via a telephone line in order to terminate upstream communication. , A plurality of transmission media are required between the CATV station and the subscriber's home. In addition, in these configuration examples, when speeding up uplink transmission by use of radio or xDSL in the future, a termination device corresponding to each system is required in the CATV center, and the configuration of the subscriber and changes in applications can be flexibly adjusted. There is a problem that it is difficult to respond.

The present invention has been made to solve the above problems, and can flexibly respond to the situation of the subscriber and the characteristics of the application. Yes, and CAT
It is an object of the present invention to provide a two-way optical CATV system capable of providing a video service and a communication service by connecting a V station and a subscriber's home with a single optical fiber.

[0013]

In order to achieve the above object, a bidirectional optical CATV system according to the present invention is provided.
In the subscriber's home, a subscriber's home device for terminating a video signal and a downlink communication signal transmitted from a CATV center and an uplink communication signal transmitted from a subscriber terminal in the subscriber's home is provided.

[0014] Also, there is one communication between the CATV center and the subscriber's house.
The CATV center is provided with means for frequency-multiplexing a video signal to be transmitted and a downstream communication signal, and means for converting the frequency-multiplexed signal into a downstream optical signal of one wavelength. The customer premises equipment is provided with means for converting an upstream communication signal to be transmitted into an optical signal having a wavelength different from that of the downstream optical signal.

Further, a coaxial cable is used for transmission between the subscriber terminal and the customer premises equipment, and the physical layer and the MAC layer of the upstream communication signal on the coaxial cable are terminated in the customer premises equipment. It is.

Further, a coaxial cable is used for transmission between the subscriber terminal and the subscriber premises equipment. In the subscriber premises equipment, the physical layer and the MAC layer of the upstream communication signal on the coaxial cable are terminated, In this configuration, an uplink communication signal transmitted from a terminal is looped back and transmitted to a subscriber terminal again.

Further, a medium for computer communication is used to transmit an upstream communication signal from the subscriber terminal to the customer premises equipment, and the physical layer and the MAC of the upstream communication signal on the computer communication medium are transmitted to the subscriber premises equipment. The layers are terminated.

Further, a telephone line is used for transmitting the upstream communication signal from the subscriber terminal to the subscriber premises apparatus, and the physical layer and the MAC layer of the upstream communication signal on the telephone line are terminated in the subscriber premises apparatus. Things.

Further, a medium for computer communication is used for transmitting upstream and downstream communication signals between the subscriber terminal and the customer premises equipment, and the physical communication of the upstream communication signal on the medium for computer communication is performed in the customer premises equipment. In addition to terminating the layers and the MAC layer, a downlink communication signal is extracted from a signal obtained by frequency-multiplexing a video signal and a downlink communication signal, and demodulated.

In addition, a telephone line is used for transmitting upstream and downstream communication signals between the subscriber terminal and the customer premises equipment. In the customer premises equipment, the physical layer and the MAC layer of the upstream and downstream communication signals on the telephone line are connected. In addition to termination, the downstream communication signal is extracted from a signal obtained by frequency-multiplexing the video signal and the downstream communication signal and demodulated.

In addition, there is one communication between the CATV center and the subscriber's house.
The cable is connected by an optical fiber, and in the CATV center, the video signal to be transmitted and the downstream communication signal are converted into downstream optical signals of different wavelengths. Is converted into an optical signal having a different wavelength.

A coaxial cable is used for transmission between the subscriber terminal and the customer premises equipment. In the customer premises equipment, the physical layer and the MAC layer of the upstream communication signal on the coaxial cable are terminated, and the electric signal is transmitted. And means for modulating a carrier with the down-converted communication signal and frequency-multiplexing the modulated signal and the video signal.

A coaxial cable is used for transmission between the subscriber terminal and the customer premises equipment. In the customer premises equipment, the physical layer and the MAC layer of the upstream communication signal on the coaxial cable are terminated, and the electric signal is transmitted. The carrier wave is modulated by the downlink communication signal converted to the above, the modulated signal and the video signal are frequency-multiplexed, and the uplink communication signal transmitted from the subscriber terminal is returned and transmitted to the subscriber terminal again. Things.

Further, a medium for computer communication is used for transmission of an upstream communication signal from the subscriber terminal to the customer premises equipment, and the physical layer and the MAC of the upstream communication signal on the computer communication medium are used in the customer premises equipment. In addition to terminating the layers, the carrier is modulated by the downstream communication signal converted into the electric signal, and the modulated signal and the video signal are frequency-multiplexed.

Also, a telephone line is used for transmitting an upstream communication signal from the subscriber terminal to the subscriber premises equipment, and the subscriber premises equipment terminates the physical layer and the MAC layer of the upstream communication signal on the telephone line, The carrier wave is modulated by the downlink communication signal converted into the signal, and the modulated signal and the video signal are frequency-multiplexed.

Further, a medium for computer communication is used for transmitting uplink and downlink communication signals between the subscriber terminal and the customer premises equipment, and the physical communication of the upstream communication signal on the computer communication medium is performed in the subscriber premises equipment. Of the downstream communication signal converted to an electric signal while terminating the MAC layer and the MAC layer.
The C layer is terminated.

In addition, a telephone line is used for transmitting uplink and downlink communication signals between the subscriber terminal and the subscriber premises equipment, and the subscriber premises equipment terminates the physical layer and the MAC layer of the uplink communication signal on the telephone line. , The MAC layer of the downstream communication signal converted into the electric signal is terminated.

That is, the present invention uses an optical fiber as a transmission path between a CATV center and a subscriber's home,
A communication center is provided between the CATV center and the subscriber's home for efficient signal transmission between the TV center and the subscriber's home through an optical fiber, and lines are concentrated between the CATV center and the communication center. It is like that.

At the subscriber's home, a home device is installed to terminate the optical fiber. When this in-house device is applied to an apartment house, it can be installed for each apartment house. The video signal and the downstream communication signal are converted from an optical signal to an electric signal in the home device.

In the upstream transmission, the in-home device converts an upstream communication signal from the subscriber's home into an optical signal and sends it out to the optical fiber of the subscriber line. Further, the home device terminates the physical layer and the MAC layer of the upstream and downstream communication signals as necessary. The interface on the center side of each in-home device is unified and does not depend on the type of medium in the home, so it does not depend on the configuration of the subscriber home or changes in applications.

On the optical fiber, bidirectional transmission is realized by a single optical fiber by wavelength-multiplexing the unidirectional video analog signal and the bidirectional communication signal. Alternatively, as in the case of an upstream signal, a binary signal is transmitted and wavelength-multiplexed with a video signal, thereby providing a video transmission service and a two-way communication service with a single optical fiber.

[0032]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a bidirectional optical CATV system according to a first embodiment of the present invention. As shown in FIG. 1, in the present embodiment, the bidirectional optical CATV system includes a video light transmitting device 11, a communication light receiving device 12 installed in the CATV center 1, and a video installed in the communication center 5. Home station device 6, communication station internal device 7, home device 3 installed in subscriber homes 2A and 2B.
A, 3B.

Optical fibers 9, 9A, 9B are connected between the CATV center 1 and the communication center 5, and between the communication center 5 and the subscriber homes 2A, 2B. Here, CATV
The communication center 5 is installed between the center 1 and the subscriber homes 2A and 2B.
May be installed in the CATV center 1 to directly connect the CATV center 1 and the subscriber homes 2A and 2B.

The video signal is an analog signal composed of a plurality of channels and frequency-multiplexed. This video signal is
The optical signal is converted into an analog optical signal by the optical transmitter for video 11, and is sent to the in-station apparatus for video 6 via the optical fiber 9. The video in-station device 6 can be composed of a branching unit 61 for distributing the optical signal for video to each subscriber, and an amplifying unit 62 for compensating for a decrease in light intensity due to the branching.

In-home devices 3A, 3 in subscriber homes 2A, 2B
B includes a photoelectric conversion unit (not shown), and an optical cable 9.
The optical signal for video received from A, 9B is converted into an electric signal for video. The converted video electric signal is transmitted to a coaxial cable in the house. CAT
When input is made to the V tuner, the video can be viewed on a television receiver connected to the tuner.

In the present embodiment, uplink transmission through a communication transmission path is possible. It is available for interactive CATV services such as Internet access, pay-per-view, and video-on-demand. The communication in-station device 7 installed in the communication center 5 includes a subscriber-side optical termination unit 71 and a service interface 72.

The subscriber-side optical termination unit 71 is connected to the subscriber's home 2A, 2
An optical-electrical converter for receiving the optical signal for upstream communication from B and an electro-optical converter for transmitting the optical signal for downstream communication to the subscriber's home are provided (not shown). The optical signals for upstream communication from the optical cables 9A and 9B are converted into electric signals by the optical terminal unit 71 on the subscriber side and passed to the service interface 72.
The service interface 72 is connected to the service providing device 8 such as a telephone exchange or an Internet connection router, and can provide various communication services.

On the inside of the home devices 3A and 3B, interfaces corresponding to various media such as a coaxial cable, a home LAN, and a telephone line are provided. These interfaces correspond to the service providing device 8 connected to the communication station device 7. ing. In order to make the transmission system between the in-home device for communication 7 and the in-home devices 3A and 3B the same regardless of the transmission path and the type of service in the in-home portion, the in-home devices 3A and 3B need Terminate the upstream signal and perform speed conversion and protocol conversion.

FIG. 2 shows a method of multiplexing the video signal and the upstream and downstream communication signals. Video signals are what itself by frequency multiplexing a plurality of channels is modulated in the video transmitting apparatus 13 to the carrier f _V AM like. In addition, the downstream communication signal is QAM-converted to the carrier f _C by the communication modulator 14.
And so on.

The video signal and the downstream communication signal are multiplexed, converted into an optical signal (λ _V ) in the video optical transmitter 11, and transmitted to the communication center 5 via the optical fiber 9. The in-home device 3A of the subscriber's home 2A receives the optical signal (λ _V ) from the communication center 5 via the optical fiber 9A, converts it according to the in-home line system, and outputs it to the terminal 21A.

On the other hand, the upstream communication signal is transmitted from the terminal 21A of the subscriber's home 2A in accordance with the home line system.
The in-home device 3A terminates the physical layer and the MAC layer as necessary, converts the upstream communication signal from the terminal 21A into a baseband optical signal (λ _C ), and transmits the signal to the communication center 5 via the optical fiber 9A. I do. The communication optical receiver 12 receives an optical signal (λ _C ′) from the communication center 5 via the optical fiber 9, converts this into an electrical signal, and then controls the controller or service providing device via the LAN 16. Distribute to 15.

As described above, for the optical signal for image and the optical signal for communication, for example, the image wavelength is λ _V and the communication wavelength is λ _C
By multiplexing at different wavelengths such as (λ _V ≠ λ _C ), the CATV center 1, the communication center 5, and the communication center 5
And the subscriber home 2A can be connected by a single optical fiber 9, 9A, and a video transmission service using an analog signal and a communication service using a binary signal can be simultaneously provided. For the optical signal for communication, different wavelengths may be used between the CATV center 1 and the communication center 5 and between the communication center 5 and the subscriber homes 2A and 2B.

FIG. 3 is a block diagram showing a configuration example of a two-way optical CATV system according to a second embodiment of the present invention, particularly showing a subscriber home part. In the present embodiment, Internet access is assumed, and a system incorporating an RF return type CM is configured.
The home device 3 of the subscriber home 2 includes a photoelectric conversion unit 31, a cable interface 32, and a center-side interface 3.
3. It is composed of an electro-optical converter 34.

In this case, the downlink communication signal has a carrier wave of 64Q.
The signal is modulated by AM or the like, and is frequency-multiplexed to a video signal. This downstream communication signal is converted into an electric signal by the photoelectric conversion unit 31 and sent to the coaxial cable 22 in the house.

The upstream communication signal from the house is terminated at the cable interface. The cable interface 32 includes a part that processes a physical layer and a MAC layer,
For example, in a CM that uses QPSK as the modulation method for uplink transmission, Q
It can be composed of a PSK demodulation unit and a MAC processing unit corresponding to the type of CM. The data processed and extracted by the cable interface 32 is processed by the center-side interface 33, converted into an optical signal (λ _C ) by the electro-optical converter 34, and transmitted to the center.

FIG. 4 is a block diagram showing a configuration example of a bidirectional optical CATV system according to a third embodiment of the present invention, particularly showing a subscriber's home part. In the present embodiment, a system is configured in which the in-home device 3 of the second embodiment incorporates a function of turning up and down transmission in the home by the in-home device.

In this case, by providing the in-home device 3 with the RF turn-back section 35 as such a turn-back function, communication between terminals in the subscriber house 2 connected via the coaxial cable 22 becomes possible. . Therefore, according to the present embodiment, communication between two CMs or between a CM and the D-STB becomes possible.

In order to realize such a configuration, between the in-home device 3 and the terminal, a down signal from the CATV center 1 side, an up signal from the terminal 21, and a down signal returned by the in-home device 3 Use different types of signals. These use different frequencies to avoid collisions. Further, the downlink signal returned by the in-home device 3 has a simple physical layer and MAC layer other than the uplink signal and the frequency, so that the RF return unit 35 has a simple configuration including a band-pass filter and a frequency conversion unit. can do.

Here, the upstream signal from the terminal includes CAT
Some are sent to the V center 1 and some are turned back by the home device 3. However, by filtering by the cable interface 32 or the center-side interface 33 according to the destination address of the packet, it is possible to prevent the packet returned by the in-home device 3 from being sent to the CATV center 1 side.

As described above, in addition to the communication in the up / down direction via the coaxial cable, a configuration using a separate line for the up transmission is also conceivable. In this case, it is advantageous to add a function of terminating the physical layer and the MAC layer of the upstream signal corresponding to the home upstream transmission system.

FIG. 5 is a block diagram showing a configuration example of a bidirectional optical CATV system according to a fourth embodiment of the present invention, particularly showing a subscriber's home part. In the present embodiment, a CM is incorporated as in the second embodiment (see FIG. 3).
An example using a transmission path for computer communication such as Ethernet using Base-T is shown.

In this case, the home device 3 is provided with a LAN interface 32A for 10Base-T instead of the cable interface 32. The upstream communication signal from each terminal is received and terminated by the LAN interface 32A. The LAN interface 32A is composed of a part for processing the physical layer and the MAC layer, and is, for example, 10 Bass.
An e-T physical processing unit and an EtherMAC processing unit can be used.

The data processed and generated by the LAN interface 32 A is transmitted to the center side interface 33.
, And is converted into an optical signal by the electro-optical converter 34 and transmitted to the center side. Media used for computer communication include wireless (including light), optical fiber, and coaxial cables in addition to twisted pair cables such as 10Base-T. When these media are used, they are adapted to the media. By providing a processing unit of the physical layer, it can be used as an in-home uplink transmission path.

FIG. 6 is a block diagram showing a configuration example of a bidirectional optical CATV system according to a fifth embodiment of the present invention, particularly showing a subscriber's home part. In the present embodiment, a telephone interface 32B having a telephone line connector is provided instead of the cable interface 32 of the in-home device 3 of the second embodiment (see FIG. 3).

The V.V. 3
With the provision of the four physical processing units and the PPP processing unit, it is possible to realize a telephone return system including a dial-up telephone modem. There is also a method of applying xDSL to increase the speed of uplink transmission in this configuration. Note that the V.V. X instead of 34 physical processing units
This can be realized by using a physical processing unit for DSL.

FIG. 7 is a block diagram showing a configuration example of a bidirectional optical CATV system according to a sixth embodiment of the present invention, particularly showing a subscriber's home part. In the present embodiment, a medium for computer communication such as Ethernet in 10Base-T is used for upstream and downstream transmission in a house. Here, a LAN interface 32A and a cable interface 36 are provided in order to separate the downstream communication signal multiplexed into the video signal by the in-home device and send it to the medium for computer communication.

The cable interface 36 is for terminating a downstream communication signal, and includes a band pass filter, a QAM demodulation unit, and a MAC processing unit. The signal processed by the band pass filter and the QAM demodulation unit is waved to the MAC processing unit, where the MAC layer is terminated and necessary data is extracted. The extracted downlink data is LA
The data is passed to the N interface, the physical layer and the MAC layer are processed in accordance with the home LAN system, and are sent to the home computer communication medium.

On the other hand, the upstream communication signal received from the home computer communication medium is processed in the physical layer and the MAC layer by the LAN interface 32A, and is taken out as upstream data. The upstream data is processed by the center-side interface 33, converted into an optical signal by the electro-optical converter 34, and sent to the communication station 7.

Media used for computer communication include wireless (including light), optical fiber, and coaxial cables in addition to twisted pair cables such as 10Base-T. When these media are used, they can be used as in-home uplink transmission lines by providing a processing unit of a physical layer according to the media.

FIG. 8 is a block diagram showing a configuration example of a bidirectional optical CATV system according to a seventh embodiment of the present invention, particularly showing a subscriber's home part. In the present embodiment, a telephone line is used for inbound and outbound transmission at home. In this case, similarly to the sixth embodiment (see FIG. 7), a cable interface 36 for separating a downstream communication signal multiplexed into a video signal is provided, and a telephone interface 32B is provided.

The cable interface 36 comprises a band-pass filter, a QAM demodulation unit, and a MAC processing unit. The downlink data extracted by the cable interface 36 is passed to the telephone interface 32B, where the physical layer and the MAC layer are processed, and transmitted to the telephone line in the house.

On the other hand, the physical layer and the MAC layer are processed by the telephone interface 32B for the upstream communication signal received from the telephone line in the house, and the upstream data is generated. The upstream data is processed by the center-side interface 33, converted into an optical signal by the electro-optical converter 34, and sent to the center. In addition, V.V. of the telephone interface 32B. 3
If the four physical processing units are changed to xDSL modulation / demodulation units, the speed of uplink transmission can be increased.

As a transmission method between the CATV center 1 or the communication center 5 and the subscriber's house, in addition to a method of transmitting a frequency-multiplexed downstream communication signal and a video signal as an optical signal of one wavelength, a video signal and a video signal are transmitted. Downlink communication may be transmitted by optical signals of different wavelengths.

FIG. 9 shows another multiplexing method of the video signal and the upstream and downstream communication signals. Video signals are what itself by frequency multiplexing a plurality of channels is modulated in the video picture modulator 13 to carrier f _V AM, etc., are converted in a video optical transmitter 11 into an optical signal (lambda _V) You. Also,
The downstream communication signal output from the various control devices or the service providing device 15 is converted by the communication optical transmitting / receiving device 12 into a baseband optical signal (λ _C ′) having a wavelength different from the wavelength λ _V of the video signal. .

The optical signal (λ _V ) of the video signal and the optical signal (λ _C ′) of the downstream communication signal are wavelength-division multiplexed.
Is transmitted to the communication center 5 via The home device 3A of the subscriber home 2A receives the optical signal (λ _V ) and the optical signal (λ _C ′) from the communication center 5 via the optical fiber 9A and converts them according to the type of the home line. , Terminal 21
Output to A.

On the other hand, the upstream communication signal is transmitted from the terminal 21A of the subscriber's home 2A according to the home line system.
The in-home device 3A terminates the physical layer and the MAC layer as necessary, converts the upstream communication signal from the terminal 21A into a baseband optical signal (λ _C ), and transmits the signal to the communication center 5 via the optical fiber 9A. I do.

In the communication optical receiver 12, the communication center 5
From the optical fiber (λ _C ′) via the optical fiber 9,
After converting this into an electric signal, it is output to various control devices or the service providing device 15. According to this, the downlink communication signal can be transmitted as a binary signal. For the optical signal for communication, different wavelengths may be used between the CATV center 1 and the communication center 5 and between the communication center 5 and the subscriber homes 2A and 2B.

As described above, regarding the optical signal for video and the optical signal for communication, for example, the wavelength for video is λ _V and the wavelength for communication is λ _C
By multiplexing at different wavelengths such as (λ _V ≠ λ _C ), the CATV center 1, the communication center 5, and the communication center 5
And the subscriber home 2A can be connected by a single optical fiber 9, 9A, and a video transmission service using an analog signal and a communication service using a binary signal can be simultaneously provided.

FIG. 10 is a block diagram showing a configuration example of a bidirectional optical CATV system according to the eighth embodiment of the present invention. In the present embodiment, it is assumed that a coaxial cable is used for in-home transmission for both uplink and downlink. Here, in order to send outgoing and incoming communication optical signals to the home line, an opto-electric conversion unit 31, an electro-optical conversion unit 34A, a center-side interface 33A, and a cable interface 32C are provided.

The downstream communication signal from the CATV center 1 is converted to an electric signal by the photoelectric conversion unit 31, and the MAC layer is terminated by the center interface 33A. The cable interface 32C includes a QAM modulator, a band-pass filter, and a QAM so that the upstream and downstream communication signals can be frequency-multiplexed with the video signal on the coaxial cable 22 at home.
It is composed of a PSK demodulation unit and a MAC processing unit.

The upstream communication signal is terminated at the physical layer and the MAC layer at the cable interface 32C, subjected to MAC processing at the center interface 33A, converted into an optical signal by the electro-optical converter 34A, and transmitted to the center.
As in the case of the third embodiment (see FIG. 4), by providing such a home device 3 with a loopback function, communication between terminals connected to the coaxial cable 22 in the home becomes possible. .

FIG. 11 is a block diagram showing a configuration example of a bidirectional optical CATV system according to a ninth embodiment of the present invention, particularly showing a subscriber's home part. In the present embodiment, a system is configured in which the function of turning on / off transmission in the home by the home device is incorporated in the home device 31 of the eighth embodiment. As a result, as in the third embodiment, communication between terminals can be realized with a simple loopback function without transmitting communication closed in the home part to the outside.

FIG. 12 is a block diagram showing a configuration example of a bidirectional optical CATV system according to the tenth embodiment of the present invention, particularly showing a subscriber's home part. In the present embodiment, a coaxial cable is used for downstream transmission at home,
A twisted pair cable for computer communication is used for upstream transmission. Here, the downstream communication signal is processed in the same manner as in the eighth embodiment, except that the upstream signal from the house is processed by the LAN interface 32D.

The upstream communication signal from the house is received and terminated by the LAN interface 32D. The LAN interface 32D is composed of a part that processes the physical layer and the MAC layer, and is, for example, an Ethernet using 10Base-T.
When the net is used, it can be configured by a 10Base-T physical processing unit and an EtherMAC processing unit.

The data processed and generated by the LAN interface 32 D is transmitted to the center side interface 33.
The signal is processed by A, converted into an optical signal by the electro-optical converter 34A, and transmitted to the center side. Media used for computer communication include wireless (including light), optical fiber, and the like in addition to twisted pair cables such as 10Base-T.
Although there is a coaxial cable, when these media are used, a physical layer processing unit adapted to the media is provided so that the media can be used as an upstream transmission line in a house.

FIG. 13 is a block diagram showing a configuration example of a bidirectional optical CATV system according to an eleventh embodiment of the present invention, particularly showing a subscriber's home part. In the present embodiment, a coaxial cable is used for downstream transmission in a house, and a telephone line in the home is used for upstream transmission. Downlink communication signals are processed in the same manner as in the eighth embodiment (see FIG. 10). The physical layer and the MAC layer of the upstream communication signal are terminated by the telephone interface 32E.

The telephone interface 32E is connected to the V.30 terminal as in the case of the fifth embodiment (see FIG. 6). 34
It can be composed of a demodulation unit and a PPP processing unit. The data extracted by the telephone interface 32E is processed by the MAC layer by the center interface 33A, converted into an optical signal by the electro-optical converter 34A, and transmitted to the center.

FIG. 14 is a block diagram showing a configuration example of a bidirectional optical CATV system according to the twelfth embodiment of the present invention, particularly showing a subscriber's home. In the present embodiment, a home LAN is used for upstream and downstream transmissions in the home. Here, the in-home device 3 includes a photoelectric conversion unit 3
1. It comprises a center-side interface 33A, a LAN interface 32F, and an electro-optical converter 34A.

In this case, the downstream communication signal from the center is terminated at the center interface 33A at the MAC layer, processed at the MAC layer and the physical layer at the LAN interface 32F, and transmitted to the terminal. The upstream communication signal from the terminal side is terminated at the physical layer and the MAC layer by the LAN interface 32F,
At A, the MAC layer is processed. And the electro-optical converter 34A
Is converted into an optical signal and transmitted to the communication center.

FIG. 15 is a block diagram showing a configuration example of a bidirectional optical CATV system according to the thirteenth embodiment of the present invention, particularly showing a subscriber's home part. In the present embodiment, a telephone line in the home is used for inbound and outbound transmission in the home. Here, the in-home device 3 includes a photoelectric conversion unit 3
1. It comprises a center-side interface 33A, a telephone interface 32G, and an electro-optical converter 34A.

In this case, the downstream communication signal from the center is terminated at the center interface 33A at the MAC layer, processed at the MAC layer and the physical layer at the telephone interface 32G, and transmitted to the terminal. The upstream communication signal received from the terminal side is demodulated and MAC-terminated by the telephone interface 32G, and the center interface 33A
Process the MAC layer. Then, it is converted into an optical signal by the electro-optical converter 34A and transmitted to the communication center.

[0082]

As described above, in each of the configuration examples of the present invention, the interface on the center side is unified, and the service can be provided by a small device that can be installed in the house. In addition, it is possible to flexibly respond to the customer's home according to the circumstances of each subscriber's home and the characteristics of the application by selecting the type of home equipment, and to respond to various uplink transmission methods at the subscriber's home by simple modification. it can. Further, the CATV station and the subscriber's house can be connected by a single optical fiber, thereby providing a video service and a communication service.

[Brief description of the drawings]

FIG. 1 shows a bidirectional light C according to a first embodiment of the present invention.
It is a block diagram of an ATV system.

FIG. 2 is an explanatory diagram illustrating a multiplexing method of a video signal and an uplink / downlink communication signal.

FIG. 3 shows a bidirectional light C according to a second embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration example (subscriber home part) of the ATV system.

FIG. 4 shows a bidirectional light C according to a third embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration example (subscriber home part) of the ATV system.

FIG. 5 shows a bidirectional light C according to a fourth embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration example (subscriber home part) of the ATV system.

FIG. 6 shows a bidirectional light C according to a fifth embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration example (subscriber home part) of the ATV system.

FIG. 7 shows a bidirectional light C according to a sixth embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration example (subscriber home part) of the ATV system.

FIG. 8 shows a bidirectional light C according to a seventh embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration example (subscriber home part) of the ATV system.

FIG. 9 is an explanatory diagram showing another multiplexing method of the video signal and the uplink and downlink communication signals.

FIG. 10 is a block diagram showing a configuration example (subscriber home part) of a bidirectional optical CATV system according to an eighth embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration example (subscriber home part) of a bidirectional optical CATV system according to a ninth embodiment of the present invention.

FIG. 12 is a block diagram showing a configuration example (subscriber home part) of a bidirectional optical CATV system according to a tenth embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration example (subscriber home part) of a bidirectional optical CATV system according to an eleventh embodiment of the present invention.

FIG. 14 is a block diagram showing a configuration example (subscriber home part) of a bidirectional optical CATV system according to a twelfth embodiment of the present invention.

FIG. 15 is a block diagram showing a configuration example (subscriber home part) of a bidirectional optical CATV system according to a thirteenth embodiment of the present invention.

FIG. 16 is a block diagram showing a configuration example of a conventional bidirectional CATV system.

FIG. 17 is a block diagram showing another configuration example of a conventional bidirectional CATV system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... CATV center, 11 ... Optical transmitter for video, 12 ...
Communication optical receiving device, 13: video transmitting device, 14: communication modulating device, 15: various control devices or service providing devices, 2, 2A, 2B: subscriber homes, 21, 21A, 21B
... Terminal, 22 ... Coaxial cable, 3, 3A, 3B ... Home device, 31 ... Opto-electric conversion unit, 32, 32C, 36, 36A
... Cable interface, 32A, 32D, 32F
... LAN interface, 32B, 32E, 32G ...
Telephone interface, 33, 33A: center side interface, 34, 34A: electro-optical converter, 35: R
F-turn part, 5: Communication center, 6: In-station device for video, 61
.., Branching section, 62... Amplification section, 7... Communication station apparatus, 71.
Subscriber side optical termination unit, 72 ... service interface,
8: Service providing device, 9, 9A, 9B: Optical fiber.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Mamoru Kitamura 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo F-term within Nippon Telegraph and Telephone Corporation (reference) 5C064 BA01 BB05 BB10 BC11 BC12 BC14 BC16 BC20 BD01 BD07 BD08 EA01

Claims (15)

[Claims] 1. A CATV center and a plurality of subscriber homes are connected by an optical fiber directly or via a communication center.
A two-way CA that transmits video signals and downlink communication signals from the ATV center, and transmits uplink communication signals from the subscriber's home.
In the TV system, a subscriber premises device for terminating a video signal and a downlink communication signal transmitted from a CATV center and an uplink communication signal transmitted from a subscriber terminal in the subscriber premises is provided in the subscriber premises. A bidirectional optical CATV system. 2. The CATV center and the subscriber's house are connected by a single optical fiber, the CATV center has means for frequency multiplexing a video signal to be transmitted and a downstream communication signal, and a frequency multiplexed signal. Is converted to a downstream optical signal of one wavelength, and the subscriber premises device is provided with means for converting an upstream communication signal to be transmitted to an optical signal of a different wavelength from the downstream optical signal. The bidirectional optical CATV system according to claim 1. 3. A coaxial cable is used for transmission between the subscriber terminal and the customer premises equipment, and the subscriber premises equipment includes means for terminating a physical layer and a MAC layer of an upstream communication signal on the coaxial cable. The bidirectional optical CATV system according to claim 2, wherein: 4. A coaxial cable is used for transmission between the subscriber terminal and the customer premises equipment, and the subscriber premises equipment includes means for terminating a physical layer and a MAC layer of an upstream communication signal on the coaxial cable. 3. The bidirectional optical CATV system according to claim 2, further comprising means for returning an upstream communication signal transmitted from the subscriber terminal and transmitting the signal back to the subscriber terminal. 5. A computer communication medium is used for transmitting an uplink communication signal from the subscriber terminal to the subscriber premises apparatus, and the subscriber premises apparatus transmits a physical layer of the uplink communication signal on the computer communication medium to the physical layer. 3. The bidirectional optical CATV system according to claim 2, further comprising means for terminating the MAC layer. 6. A means for terminating a physical layer and a MAC layer of an upstream communication signal on a telephone line by using a telephone line for transmitting an upstream communication signal from the subscriber terminal to the customer premises apparatus. The bidirectional optical CATV system according to claim 2, further comprising: 7. A computer communication medium is used for transmission of upstream and downstream communication signals between the subscriber terminal and the customer premises equipment, and the physical communication of the upstream communication signal on the computer communication medium is transmitted to the subscriber premises equipment. 3. The bidirectional optical CATV according to claim 2, further comprising: means for terminating the layer and the MAC layer; and means for extracting and demodulating a downstream communication signal from a signal obtained by frequency-multiplexing the video signal and the downstream communication signal. system. 8. A telephone line is used for transmitting upstream and downstream communication signals between the subscriber terminal and the customer premises equipment, and a physical layer of upstream and downstream communication signals on the telephone line and M
3. The bidirectional optical CATV system according to claim 2, further comprising: means for terminating the AC layer, and means for extracting and demodulating a downlink communication signal from a signal obtained by frequency-multiplexing the video signal and the downlink communication signal. 9. The CATV center and the subscriber's house are connected by a single optical fiber, and the CATV center has means for converting a video signal to be transmitted and a downstream communication signal into downstream optical signals having different wavelengths. 2. The bidirectional optical CATV system according to claim 1, further comprising means for converting the upstream communication signal to be transmitted into an optical signal having a wavelength different from at least the optical signal for video to the customer premises equipment. 10. A system in which a coaxial cable is used for transmission between the subscriber terminal and the customer premises equipment, and the subscriber premises equipment includes means for terminating a physical layer and a MAC layer of an upstream communication signal on the coaxial cable. 10. The bidirectional optical CATV system according to claim 9, further comprising: means for modulating a carrier with a downstream communication signal converted into an electric signal; and means for frequency-multiplexing the modulated signal and a video signal. 11. A means for using a coaxial cable for transmission between the subscriber terminal and the customer premises equipment, and terminating the physical layer and the MAC layer of the upstream communication signal on the coaxial cable in the customer premises equipment, Means for modulating a carrier with a downstream communication signal converted into an electric signal, means for frequency multiplexing the modulated signal and a video signal, returning an upstream communication signal transmitted from the subscriber terminal and transmitting it again to the subscriber terminal 10. The bidirectional light C according to claim 9, further comprising:
ATV system. 12. A medium for computer communication is used for transmission of an upstream communication signal from the subscriber terminal to the customer premises equipment, and the physical layer and MAC of the upstream communication signal on the computer communication medium are transmitted to the customer premises equipment. Means for terminating the layers,
10. The bidirectional optical CATV system according to claim 9, further comprising: means for modulating a carrier with a downstream communication signal converted into an electric signal; and means for frequency-multiplexing the modulated signal and a video signal. 13. A means for terminating the physical layer and the MAC layer of the upstream communication signal on the telephone line using a telephone line for transmitting the upstream communication signal from the subscriber terminal to the customer premises apparatus. 10. The bidirectional optical CATV system according to claim 9, further comprising: means for modulating a carrier with a downstream communication signal converted into an electric signal; and means for frequency-multiplexing the modulated signal and a video signal. 14. A communication medium for computer communication is used for transmission of upstream and downstream communication signals between the subscriber terminal and the customer premises equipment, and the physical communication of the upstream communication signal on the computer communication medium is transmitted to the customer premises equipment. 10. The bidirectional optical CATV system according to claim 9, further comprising means for terminating the layer, the MAC layer, and means for terminating the MAC layer of the downstream communication signal converted into the electric signal. 15. A telephone line is used for transmitting uplink and downlink communication signals between the subscriber terminal and the subscriber premises equipment, and terminates the physical layer and the MAC layer of the uplink communication signal on the telephone line in the subscriber premises equipment. The bidirectional optical CATV system according to claim 9, further comprising means for terminating a MAC layer of the downstream communication signal converted into an electric signal.