JPH1070509A - Optical subscriber's cable system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the equipment constitution of a remote terminal(RT) itself and to improve cost performance by using a space dividing type switch for the RT to unnecessitate O/E conversion inside of RT to make it possible to 1:n-connect between a line terminating equipment (CT) and a network terminating equipment (ONU). SOLUTION: This system is provided with a time slot control part 405 assigning a time slot to the line terminating equipment CT of an exchanging station for each subscriber based on an ADS(active double star) system. CT and network terminating equipments ONU at respective subscriber's houses are provided with multi-rate burst conversion parts 407 and 414 for inserting or extracting fast/slow information to this time slot. In addition, the RT existing between CT and ONU is provided with a space dividing type optical switch part 409 for switching the time slot while it is still an optical signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a fiber-to-
The present invention relates to an optical subscriber line system for realizing the home (FTTH).

[0002]

2. Description of the Related Art In a conventional optical subscriber line system, a direct subscriber premises (user) and a switching center (center) 1 shown in FIG.
5 is converted to a metallic line via a remote terminal (RT) 205, and then the metallic line is drawn into the subscriber's home. An active double star (ADS) system and a passive double star (PDS) system in which a star coupler 305 is arranged instead of the RT 205 as shown in FIG. .

[0003]

In the case of the SS system described above, since the connection is 1: 1, the center 101 must have an E10 converter 104 and a subscriber terminal control circuit (CTL) 103 corresponding to each user. In addition, since the optical fiber is drawn from the straight center to the user's house, there is a disadvantage that the cost is high.

Even in the ADS system, since the area between the RT and the user is metallic, there is a drawback that the available services are limited. Further, after the O / T conversion at the RT, the line termination circuit (SLIC) 208 for the metallic for each user. There is a disadvantage that it must have.

In the case of the PDS system as disclosed in Japanese Patent Application Laid-Open No. 4-240932, since the center and the user are connected via an optical distributor such as a star coupler 305, each subscriber is connected to the center side. Although it is not necessary to provide a termination circuit for each transmission, since transmission and reception are performed in the broadcast mode, there is a drawback that the security of each user is questioned.

[0006]

SUMMARY OF THE INVENTION In the optical subscriber line system of the present invention, a time slot control circuit provided in a line termination unit of a switching center and allocating a time slot to each subscriber is provided. A multi-rate burst conversion circuit, which is provided in each of the home network terminating devices and inserts and extracts high-speed and low-speed information in the time slot, and an optical multiplex transmission provided in the remote terminal from the line terminating device and the network terminating device A space division type optical switch for switching a time slot on a road.

The optical subscriber line system according to the present invention further comprises a time slot control unit for allocating a time slot as a communication path for each subscriber, and a multi-rate burst conversion for inserting and extracting high-speed and low-speed information in the time slot. And an electrical / optical converter 4 for converting an electrical signal and an optical signal
06, a center terminal arranged in a switching center, a time slot control unit for allocating a time slot as a communication channel for each subscriber, and a multi-rate burst conversion unit for inserting and extracting high-speed and low-speed information in the time slot. An optical-to-electrical conversion unit for converting an electric signal and an optical signal, and a terminal termination unit having a terminal interface unit having an interface matching function with a terminal, arranged at the subscriber's home; A remote terminal disposed between the center terminal and the network terminating device, which comprises a space division type optical switch unit for switching as it is, and an optical switch control unit for controlling the space division type optical switch unit. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings.

The optical subscriber line system shown in FIG. 1 is an ON which accommodates exchanges 401 and CT 404 in an exchange and terminal devices such as TEL / FAX 418 in a subscriber's house.
U411, 419, and RT408 installed between the exchange and the subscriber's house.

First, regarding CT 404, RT 408
E / O converter 4 for converting an electric signal to be transmitted to an optical signal
06 and the constraint information received from the high-speed dedicated exchange 403 are converted into a time-compressed high-speed burst signal, and the compressed information is inserted into a corresponding position of a low-speed time slot fixedly assigned to each ONU. And a time slot control unit 40.
And 5. The time slot control unit 405,
E / O converter 406, multi-rate burst converter 40
Each section 7 also has a function of a receiver from the RT 408, contrary to the above-described transmission function in the direction of the RT 408.

[0011] As for the ONU 411, an O / E converter 412 for converting an optical signal from the RT 408 into an electric signal.
And a time slot control unit 413 for separating and extracting low-speed information and compressed high-speed information from the received time slot, and returning the high-speed information separated and extracted by the time slot control unit 413 to the actual speed. And the low-speed and high-speed information by P
And a terminal interface unit 415 for notifying a data terminal such as C. The O / E conversion section 412, the time slot control section 413, and the multi-rate burst conversion section 414 also have a function of transmitting each information from each terminal in the direction of the RT 408, contrary to the above.

For the RT 408, a time slot on the optical multiplex transmission line received from the CT 404 is switched as it is as an optical signal, and a 1: n space division type optical switching unit 409 for transmitting to the plurality of ONUs 411 and 419, and its switch Switch control circuit section 410 for controlling section 409
It is composed of In addition, the space division type optical switch 40
9. Conversely, the optical switch control circuit 410 also has an n: 1 switching function for transmitting time slots received from the plurality of ONUs 411 and 419 to the CT 404 and a control function thereof.

Next, the operation will be described. Since there is an operation of transmitting information from the exchange to the subscriber's home and an operation on the opposite side, the operation from the exchange to the subscriber's home will be described.
First, as a prerequisite, an optical multiplex transmission path (highway) in both directions of transmission and reception between the CT 404 to the RT 408 has a time slot configuration 501 as shown in FIG. 2, and an ONU number is fixedly assigned to each time slot. The low-speed and high-speed information output from the exchange 401 is time-compressed by the CT 404 at the CT 404, and the high-speed information is compressed by the multi-rate burst converter 407. It is inserted into the high-speed information area 502 of the ONU number, E / O converted, and output to the RT 408. In the time slot control unit 405, the corresponding O
It also inserts low-speed information into the low-speed information area 503 of the NU number and inserts synchronization / ONU number information into the information area 504.

In the RT 408, information received from the CT 404 by the space division type optical switch unit 409 is transmitted to each ONU 4
11,419. The control is performed using the optical switch control circuit 410. As this control method, first, the CT 404 and the ONUs 411 and 419 are fixedly connected to the input / output path of the space division type optical switch unit 409. As for the assignment, one of the input side routes is C
The optical multiplex transmission line received from T404 is fixedly assigned to the ONUs 411 and 419 corresponding to the ONU number fixedly assigned on the optical multiplex transmission line received from CT 404 to the output side path. Next, the optical switch control circuit 410 generates a fixed switching timing signal corresponding to the ONU number, and switches the output side path of the space division type optical switch unit 409 based on the switching signal. As a result, on the output side path of the space division type optical switch unit 409, only the relevant ONU information in the optical multiplex transmission path received from the CT 404 is distributed to each path as an optical signal, and the optical transmission of the relevant ONU is performed. Output on the road. FIG. 3 shows an example of the switching.

In the ONUs 411 and 419, the received corresponding ONU information is converted from an optical signal to an electric signal by the O / E converter 412, and then the synchronization information inserted into the information area 504 is converted by the time slot controller 413. It extracts information and performs synchronization establishment control. Then, high-speed information compressed from the high-speed information area 502 and low-speed information from the regular job information area 503 are extracted. Regarding the extracted information, in the case of high-speed information, the multi-rate burst converter 414 converts the information to the original speed, and then notifies the terminal interface 415. In the case of low-speed information, the information is notified directly to the terminal interface unit 415. The terminal interface unit 415 includes a terminal data terminal 416, an interactive TV 417, a TEL / FAX
The received information is converted into an interface suitable for various terminal devices at 418, and the information is notified to various terminals.

The operation of transmitting information from the subscriber's house to the exchange is the reverse of the above operation. First, data terminal 416, interactive TV 417, TEL / FAX
The information transmitted from the various terminals 418 is the ONU 41
1 and received by the terminal interface unit 415 and interface-converted. For high-speed information, compression conversion is performed via the multi-rate burst conversion unit 414, and the time-slot control unit 413 is used. The notification is sent to the unit 413. The time slot control section 413 inserts these pieces of information into the low-speed and high-speed information areas 503 and 502, and inserts the synchronization / ONU number information into the information area 504. After that, the O / E conversion section 412 Performs light-to-light conversion and outputs it to RT4108.

In the RT 408, information coming from each ONU 411, 419 is multiplexed by using the space division type optical switch unit 409 and the optical switch control circuit 410 in the same manner as in the direction from the exchange to the subscriber's home. The multiplexing method is basically performed using the TDMA method, and each of the ON
The ONUs 411 and 419 output data on the optical transmission line using the timing created based on this information by transmitting timing information such that the uplink information from the U 411 and 419 does not collide. In the RT 408, information on the optical transmission lines from the ONUs 411 and 419 individually allocated from the exchange to the input side of the optical switch different from the subscriber's home direction is created by the optical switch control circuit 410. Multiplexing of each ONU information is performed by outputting to the corresponding ONU number position on the optical transmission path to be transmitted to the CT 404 fixedly allocated to the output image path based on the signal. The optical switch control circuit 4
With respect to the control signal created in step 10, the ONUs 411 and 419 create a signal corresponding to the ONU number fixedly allocated in the optical transmission line to be transmitted to the CT 404 at the same timing as each created by the ONUs 411 and 419 in the TDMA system. This prevents data loss due to switching.

In the CT 404, each ONU 411, 419
Conversely, after the O / E conversion of the optical signal received by the RT 408, the low-speed and high-speed information is separated from the respective areas 503 and 502 by the time slot control unit 405, and the high-speed information is converted by the multi-rate burst conversion unit 407. After the conversion to the original speed, each is notified to the high-speed information exchange 403, and the low-speed information is notified to the low-speed exchange 402.

[0019]

According to the present invention, by using a space division type switch for the RT, O / E conversion inside the RT becomes unnecessary, and 1: n connection between CT and ONU is made possible.
The device configuration of T itself can be simplified and cost performance can be improved.

Further, by using the multi-rate burst transmission system and the space division type optical switch, it is not necessary to take the broadcast mode, and the security can be improved.

Further, by connecting the user to the center by using a space division type optical switch, an optical amplifier required together with the star coupler in the PDS system is not required, and the transmission efficiency can be improved.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a highway between CT and RT.

FIG. 3 is a configuration diagram of a highway between CT and RT and between RT and ONU.

FIG. 4 is an SS (single star) system configuration diagram.

FIG. 5 is an ADS (active double star) system configuration diagram.

FIG. 6 is a configuration diagram of a PDS (passive double star) system.

[Explanation of symbols]

 401 Switchboard 402 Low-speed dedicated switch 403 High-speed dedicated switch 404 Line termination device (CT) 405 Time slot control unit 406 O / E conversion unit 407 Multirate burst conversion unit 408 Remote terminal (RT) 409 Space division type optical switch unit 410 Optical switch Control circuit 411 Network termination unit # 1 (ONU) 412 O / E conversion unit 413 Time slot control unit 414 Multi-rate burst conversion unit 415 Terminal interface unit 416 PC or other data terminal 417 Interactive TV 418 TEL / FAX 419 Network termination unit #N (ONU) 101 exchange (center) 102 exchange 103 subscriber terminal control circuit (CLT) 104 O / E converter 105 network termination unit (DSU) 106 terminal (TEL) 201 exchange (center) 202 Switch 203 Subscriber terminal control circuit (CLT) 204 O / E converter 205 Remote terminal 206 O / E converter 207 Demultiplexing control circuit (MDX) 208 Line termination circuit (SLIC) 209 Terminal (TEL) 301 Switching center ( Center) 302 exchange 303 subscriber terminal control circuit (CTL) 304 O / E converter 305 star coupler 306 O / E converter 307 network termination circuit (CTL) 308 terminal (TEL)

Claims (2)

[Claims] 1. A time slot control circuit provided in a line terminating device of an exchange and allocating a time slot to each subscriber, and a time slot control circuit provided in each of the line terminating device and a network terminating device at each subscriber's home. A multi-rate burst conversion circuit for inserting and extracting high-speed and low-speed information; and a space division type optical switch provided at a remote terminal for switching a time slot on an optical multiplex transmission line from the line terminating device and the network terminating device. An optical subscriber line system, comprising: 2. A time slot control section for allocating a time slot as a communication path for each subscriber, a multi-rate burst conversion section for inserting and extracting high-speed and low-speed information in the time slot, and an electric signal and an optical signal. A switching center-arranged center terminal composed of an electric / optical conversion unit 406 for conversion; a time slot control unit for allocating a time slot as a communication channel for each subscriber; A network terminating device arranged at a subscriber's home, comprising a multi-rate burst converter for extracting, an optical-to-electrical converter for converting an electric signal and an optical signal, and a terminal interface unit having an interface matching function with a terminal; A space division type optical switch unit for switching a time slot as an optical signal, and the space division type optical switch An optical subscriber line system, comprising: a center terminal comprising an optical switch control unit for controlling the unit; and a remote terminal disposed between the network terminal device.