JPH11298410A - Optical transmission system and its monitoring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently monitor an entire system, to improve the reliability of the entire system and to reduce cost by making one of optical transmission subsystems which respectively have a monitor controlling part an active system and the other one a standby system. SOLUTION: In a system of a minimum configuration, end terminals(ET) 52 and 53 and bidirectional optical repeaters (LA) 54 and 55 are provided with monitor controlling parts 56, 59, 57 and 58. The two systems are serially connected through a reproduction relaying device (LRE) 51 to construct a system and four systems of it are used. The parts 56 to 59 in one system and a monitoring optical signal that is transmitted and received between them are used for the active system and the parts 56 to 59 in the other system and a monitoring optical signal that is transmitted and received between them are used for the standby system. These two systems monitor the entire four systems.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission system and a monitoring method thereof, and more particularly, to a wavelength division multiplexer (WDM).
Wavelength division Multiplexing equipment and Wavelength division Demultiplexing equipme
nt) and an optical transmission system for transmitting a wavelength-division multiplexed optical signal and a monitoring method thereof.

[0002]

2. Description of the Related Art A conventional optical transmission system is disclosed in Japanese Patent Application No. Hei.
No. 44098 discloses an optical repeater that transmits a wavelength-multiplexed main optical signal in one optical fiber inserted in the middle, and also monitors signals such as monitoring information between devices constituting the system. Monitoring light (OSC: Optical service)
channel) signal is multiplexed with the main optical signal and transmitted.

[0003]

In the optical transmission system according to the above-mentioned prior art, the system monitoring method when a plurality of systems are operated is not sufficiently considered, and the monitoring means is independently provided for each system. Since such a system is provided, the work for monitoring and the like becomes complicated, and the reliability of the whole system cannot be made higher than the operation of a single system alone. Was.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to efficiently monitor the entire system even when operating with a plurality of optical transmission systems, and to improve the reliability of the entire system. It is an object of the present invention to provide an optical transmission system capable of improving the cost and reducing the cost, and a monitoring method thereof.

[0005]

According to the present invention, the object comprises a plurality of optical transmission subsystems arranged in parallel for transmitting one of the plurality of optical main signals; Each of the subsystems has a supervisory control unit, two of the plurality of optical transmission subsystems each have an optical supervisory signal transmission unit, one of the optical supervisory signal processing units is a working system, and the other is One is achieved by an optical transmission system that transmits monitoring information of the plurality of optical transmission subsystems as a maintenance system.

Further, the object is to provide a first optical transmission subsystem including a first optical supervisory signal transmitting unit for transmitting an optical supervisory signal, and a second optical supervisory signal transmitting unit for transmitting the optical supervisory signal. A second optical transmission subsystem including a second optical transmission subsystem, a regenerative repeater for regenerating and relaying the optical main signal, and connecting the first optical monitoring signal transmission unit and the second optical monitoring signal transmission unit; An optical fiber for transmitting a signal;
The optical transmission subsystem, the regenerative repeater, and the second
Is achieved by an optical transmission system connected in series.

Further, the object is a method of monitoring an optical transmission system for transmitting a plurality of optical main signals by arranging a plurality of optical transmission subsystems in parallel, wherein each of the plurality of optical transmission subsystems is A monitoring control unit, two of the plurality of optical transmission subsystems each include an optical monitoring signal processing unit, and one of the optical monitoring signal processing units is a working system;
Another one is a maintenance system, a step of monitoring the plurality of optical transmission subsystems, and a step of multiplexing monitoring information of the plurality of optical transmission subsystems into one of the plurality of optical main signals. Transmitting the multiplexed optical signal.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a wavelength division multiplexing / demultiplexing device (WD)
The basic concept of an optical transmission system for transmitting a wavelength multiplexed optical signal using M) and a monitoring method thereof will be described.

FIG. 1 is a diagram showing various configurations of an optical transmission system for transmitting a wavelength-division multiplexed optical signal using a wavelength division multiplexing / demultiplexing device. FIGS. It is a figure explaining the monitoring method transmitted to an end terminal. 1 to 6, ET denotes an end terminal, LA and reference numerals 22, 23, 25, and 26 denote optical repeaters, 21 and 24 denote wavelength multiplexing / demultiplexing devices, and 27 denotes an OSC termination unit.

There are several types of optical transmission systems depending on the degree of multiplexing of the optical signal, the handling of the transmission direction of the optical signal in the optical fiber, and the like.

The system shown in FIG. 1A is for transmitting optical signals of four wavelengths each for upstream and downstream in one optical fiber. This system multiplexes the transmission optical signals of wavelengths λ1 to λ4 (λ1 ′ to λ4 ′) from a plurality of terminal devices (not shown), and transmits the wavelengths λ1 ′ to λ1 ′ to
an end terminal (ET) including a wavelength division multiplexing / demultiplexing device (DWDM) for separating a received optical signal of λ4 ′ (λ1 to λ4) and transmitting the signal to a terminal device; an optical fiber connecting between the two ETs; It comprises one or a plurality of bidirectional optical repeaters inserted in the middle of the optical fiber. In general, 1
Since an optical signal of two wavelengths can transmit a signal of 10 Gbit / s, the system shown in FIG.
A signal of 0 Gbit / s can be transmitted bidirectionally. Note that ET8B in the figure is a bi-directional eight-wavelength type.
Is the meaning of The same applies to LA8B.

The system shown in FIG. 1 (b) is for transmitting optical signals of eight wavelengths each for up and down in one optical fiber. This system is different from FIG. 1 in that wavelengths λ1 to λ8 and λ1 ′ to λ8 ′ are used as optical signals to be used.
It has the same configuration as the system shown in FIG. This system can transmit a signal of up to 80 Gbit / s in both directions.

The system shown in FIG. 1 (c) uses a dedicated optical fiber for each signal transmission direction, uses optical signals of 16 wavelengths for both upstream and downstream, and is inserted along the optical fiber. LA is configured to be unidirectional. Since the system of this example uses an optical signal of 16 wavelengths, a signal of a maximum of 160 Gbit / s can be transmitted in both directions. Note that ET16U in the figure means 16 kinds of wavelengths, Uni-directional. Also, LA1
The same applies to 6U.

Next, a method of transferring fault information including fault location information to a WDM in an end terminal using a monitoring light signal will be described with reference to FIGS.

In FIG. 2, the normal OSC signal is an optical signal used for transmitting monitoring information having a wavelength different from that of the main optical signal, and is transmitted after being wavelength-multiplexed with the main signal.
However, while the main signal is amplified as it is by the optical amplifiers in the LAs 22 and 23, the monitoring optical signal is
The optical signal is separated from the main optical signal at the entrances of the LAs 22 and 23, and is optically / electrically converted by the OSC termination unit 27 shown in FIG. The monitoring electric signal converted into the electric signal is provided with monitoring information to a monitoring information control unit (not shown), and then the monitoring information of the LAs 22 and 23 is added. The monitoring optical signal converted into the optical signal is multiplexed again with the main optical signal at the exits of the LAs 22 and 23. The configuration of the OSC termination unit described above is the configuration of FIG. 9B described later.
The configuration shown in FIG. 9A, FIG. 9C or FIG. 9D may be used.

An ID for identifying the device is defined in each of the LAs 22 and 23 inserted in the middle of the relay optical fiber. An ID number is simply assigned. In FIG. 2, it is assumed that an optical fiber breakage between the WDM 21 and the LA 22 has occurred. Then, LA = 2 of ID = 2
2 is a disconnection of the input transmission line (no optical signal: LOS: Loss ofsi
gnal). Since the LA 22 cannot transmit an optical signal, the LA 22 performs a control of shutting down the output level. Similarly, the LA 23 detects the LOS and performs the shutdown control. As a result, the DWDM 24 can also detect the LOS.

The LA 22 simultaneously transmits WDM-AIS information (Wavelength Division Multipl) defined on the OSC.
exed-Alarm Indication Signal) is set to the AIS generation state, and ID = 2 is added as ID information and transferred downstream.

In other words, this example utilizes the fact that, when the input transmission line is disconnected, the OSC input is naturally disconnected at the same time, but the output OSC can be transmitted. Finally, the above-described information is transmitted to the downstream WDM 24, and in the downstream WDM 24, it is possible to specify the location where the transmission path has failed.

In the example shown in FIG. 3, in addition to the example of FIG. 2, failure information is further transmitted in the opposite direction to a WDM-RDI (Remote Defec
t Indication) is transmitted as information to notify the upstream WDM 21 in the opposite direction of the failure. As a result, the upstream WDM 21 can detect that the signal output by itself cannot be transmitted to the opposite side, and can also detect a failure location. Normally, the transmission signal is normal with bidirectional transmission established,
Since it is meaningless that only one of them is normal, various applied operations such as blocking of a signal can be performed using this. This example is particularly effective in the case of a one-way system in which upstream and downstream fibers are separately provided as shown in FIG.

In FIG. 3, the WDM-AIS and the downstream WDM 24 that has received the fault location information (ID information)
Uses the OSC heading in the opposite direction to generate WDM-RD
I and the fault location information. With this, W on the opposite side
The DM 21 can detect that an abnormality has occurred on its own transmission side, and detect the failure position.

FIG. 4 is a diagram for explaining the OSC termination unit 27 in the LA 22, which is an apparatus constituting the optical transmission system. OSC signals are typically slow optical signals,
The low-speed optical signal is connected to the WDM. As described above, the OSC is very important for monitoring the optical transmission system, and if the OSC itself breaks down, the monitoring system may malfunction. For example, the example described with reference to FIGS. 2 and 3 is a case where a failure occurs in an optical fiber portion (point A in FIG. 4) wavelength-multiplexed with a main signal. However, when only the OSC signal is disconnected, it is necessary to consider, for example, the failure of the OSC termination unit 27 or the disconnection at the point B in FIG.

FIG. 5 shows the operation when point B in FIG. 4 is disconnected. When the point B is disconnected, the disconnection at the point B is detected by the OSC termination unit 27. The OSC terminating unit 27 transfers OSC-AIS information and fault location information downstream from the WDM-AIS defined on the OSC. These information are transmitted downstream, and finally W
The WDM 24 detects that the OSC signal is disconnected between the WDM 21 and the WDM 21.
The failure location can be specified. In this operation, OSC-RDI in the opposite direction is defined as in the case of WDM-AIS. Use is WDM-RD
Same as I.

Next, referring to FIG. 6, a description will be given of the overall operation of transmitting failure information by the WDM-AIS and the OSC-AIS. In FIG. 6, it is assumed that a fiber breakage fault has occurred at a point A on a transmission line using an optical fiber. LA22 which detected this failure by no optical signal (LOS)
At the same time, WDM-AIS, OS
Simultaneous transfer of C-AIS is performed. These are finally detected by the downstream WDM 24 to make a comprehensive judgment. That is, if WDM-AIS and OSC-AIS are detected at the same location, it is determined that the fiber has failed, and the OSC-AIS is detected.
If only S is detected, it can be determined that the failure is only in the OSC-related part.

In the above, the outline of monitoring the entire system by multiplexing the monitoring light (OSC) in the optical transmission system has been described. Usually, in an optical transmission system, N rows of systems are often installed in parallel. In that case, there is no need to provide a plurality of OSCs. That is, the number of OSCs can be reduced by utilizing the fact that the system is a plurality of parallel systems. Further, when one OSC is shut down due to a failure in the transmission path, it is possible to protect the monitoring network by using the route of another OSC.

FIG. 7 is a block diagram showing an outline of a configuration example of an optical transmission system in the case of one system. FIG. 8 is a block diagram showing an outline of a configuration example of a parallel optical transmission system in which two systems are provided in parallel. FIG. 9 is a diagram for explaining a method of dividing the functions of the OSC, which will be described below. FIG.
9, 21 ′ and 24 ′ are WDM, 2
2 ', 23', 25 ', 26' are LA, 28-33, 4
0 to 46 are OSC termination units, and 34 to 39 are selectors (SE
L), and the other reference numerals are the same as those in FIGS.

The example shown in FIG.
In this case, since only the system is provided, only one system of the OSC is installed, and no spare system is installed for the system of the OSC. Then, the OSC termination unit 28
Are input / output units of the WDM 21 and OSC termination units 29 and 30
Are input / output units of the LAs 22 and 26 and OSC termination units 31 and 3
2 is an input / output unit of the LA 23, 25, an OSC termination unit 33
Are provided in the input / output unit of the WDM 24. With this configuration, the OSC is multiplexed with the main optical signal and transmitted to each span between the WDM and the LA and between the LAs and the LA. The main function of the OSC termination units 28 to 33 is DCC (Data Commun
Providing a data communication line called "communication channel" (used for transferring monitoring information between devices, etc.)
And providing a telephone line for meetings called OW (OrderWire).

In the case of a two-system parallel system as shown in FIG. 8, the main signals are two independent systems, and the OSC is provided with an OSC Working Line and a backup OSC Correction Line. Each device is provided with a selector function for the OSC switching function. The example shown in FIG. 8 shows the most general selector function, and the respective selector circuits are indicated by Span numbers as SEL 1-Ea or the like.

In FIG. 7 and FIG.
Although it is divided so that it is transmitted every time, as shown in Fig. 9, there are several ways to divide the function of the OSC part as a method of dividing its function into printed circuit board package units. Then, FIG.
Is determined as the control method of the selector circuit shown in FIG. This is to cope with the fact that the unit called the printed circuit board package is a replacement unit at the time of failure.

Referring to FIG. 9 for explaining the division of the OSC function, the example shown in FIG. 9A is a form of division by West / East, and the example shown in FIG. 9B is West to East / Eas.
The format in which division is performed in the direction of t to West, the example shown in FIG. 9C is a format in which all are divided, and the example shown in FIG.
All are in one exchange unit. These are O
It is determined from conditions such as the circuit size of the SC unit, operating conditions when the package is removed, and the like.

In accordance with the configuration shown in FIG. 9, an individual selector operation method of each device shown in FIG. 8 is determined. This is called a switching mode (Protection Mode), and is a bidirectional switching mode for each Span suitable for the configuration of FIG. 9A, an All Span one-way switching mode suitable for the configuration of FIG. 9B, and FIG.
Span-dependent one-way switching mode suitable for the configuration of FIG.
There is an All Span bidirectional switching mode suitable for the above configuration.

For example, the OSC shown in FIG.
In the bidirectional switching mode for each span suitable for the case where the configuration is made for each t / East, the switching in each span is made independent. However, in each span, an operation is performed so as to switch Woking / Protection simultaneously with the selector of the opposing OSC. In this case, when any of the transmission lines detects a failure, the opposing device needs to contact the opposing side via Span to perform switching, and a communication channel for that purpose is defined on the OSC.

For this definition, for example, two failure levels are defined: SF: Signal Failure (signal loss: transmission path loss or loss of frame synchronization) SD: Signal Degrade (signal degradation: error rate degradation). Then, the device opposed via Span detects the alarm (SF, SD, Working / P
protection) is always notified to the opposite side. Each apparatus switches the working / protection by judging the selection system by comparing both the alarm on the opposite side and the alarm detected by itself. Then, the above-mentioned notification to the opposite side is sent to the OSC-S
F and OSC-SD are detected by returning OSC-SF-RDI and OSC-SD-RDI to the opposite side of Span.

In the above, the case of switching by Span has been described. In the case of All Span switching, it is not necessary to exchange such information for each Span. Instead, OSC is common to all Spans
-Define SF, SD, etc., and use them facing WDM. For example, in the case of the All Span bidirectional switching mode, the DWDM determines the selection system by the same determination method as described above, and simultaneously switches all devices by transferring the selection information to the LA.

The OSC described above has a SONET OC-N frame structure, for example, a SONET OC-N.
3 (155.52 Mb / s) frame format can be applied.

The merits of applying this frame format are as follows: (1) Information communicated by OSC includes DCC, O
Although there is W, etc., by adopting the SONET frame configuration, the LSI or the overhead processing circuit configuration developed by SONET can be used as it is.

(2) The circuit configuration can be diverted,
A substantially similar configuration can be used for the monitoring system configuration and the like.

(3) Ensuring a sufficient communication capacity even in the future of 156 Mb / s makes it easy to expand functions.

(4) The OSC monitoring optical network is connected to the SO
When expanding including the NET device, particularly, the already developed OC-3 package can be easily accommodated in the SONET-side device, and the consistency can be ensured.

And the like can be obtained.

Normally, a monitoring network using a DCC is adopted between SONET devices. When a WDM network is integrated with the monitoring network, an OSC is connected between the WDM and the SONET device in a wavelength multiplexing format. In that case, S
It is possible to equip the ONET device with an OC-3Card that is the same as before and only differs in wavelength.
It is easy to connect using C.

An example of a monitoring method according to an embodiment of the present invention will be described with reference to FIGS. FIG. 24 shows an OC-3 (STM-1) embedded information transfer function between devices.
2 shows the overhead part of FIG. Here, the combination of one alphabetic character such as A1 byte and a number is SONET, SD
H is a byte for synchronization and the like defined in standards such as H. In the present invention, the transfer information between the end terminals and the transfer information between all the devices are transferred by using the empty bytes in the overhead section. Line DCC using D4-D12 bytes specified by the standard is used for transfer information between end terminals.
In addition to this, SCI (device configuration information transfer function System Config
uration Indicator), CDI (LOS detection number transfer function)
Channel Down Indicator), ET1 and ET2 (spare). Also, Section D using D1-D3 bytes defined by the standard is used as transfer information between all devices.
In addition to CC, AIS (line failure transfer function), AOW1,
2 (Analogu OW, 2 channels), DOW1, 2 (Digita
l OW, 2 channels), WAID (WDM AIS generated ID),
OAID (OSC AIS generated ID), WEF (WDM FarEnd Re
ceive Error), OFE (OSC Far End Receive Erro)
r), SCCI1-3 (Superviso, supervisory control information transfer function)
ry Control Channel), LA1 and LA2 (spare).

FIG. 25 shows a specific bit allocation of the AIS byte. The upper 4 bits indicate WDMAIS, and the lower 4 bits indicate OSC AIS. "0000" indicates a normal state and "1010" indicates an AIS generation state. The device that has detected the failure performs WDM AIS,
Allocate to OSC AIS and transmit to downstream device.

FIG. 10 is a block diagram showing a configuration of an optical transmission system according to another embodiment of the present invention. In FIG. 10, reference numerals 50 and 50 'denote terminal equipments (LTE), 52 and 53.
Is an end terminal (ET), 54 and 55 are bidirectional optical repeaters (LA), 56 to 59 are supervisory controllers, 60 to 63 are bidirectional optical amplifiers, and 64 and 65 are wavelength division multiplexers (WDs).
M).

The optical transmission system according to the embodiment of the present invention shown in FIG.
The WDMs 64 and 65 and the bidirectional optical amplifiers 60 and 63 for wavelength multiplexing the transmission optical signals of a plurality of wavelengths from the E50 and 50 ′ and separating the reception optical signal from the relay optical fiber and transmitting the separated optical signals to the LTE 50 ′ and 50 ET52, 53 provided, 2
An optical fiber for connecting the two ETs 52 and 53 to each other, and one or more LAs 54 inserted in the middle of the optical fiber;
55. This configuration is the same as the configuration described with reference to FIGS. 1A and 1B.

Then, in the system shown in FIG.
52, 53 and LAs 54, 55 include a monitoring control unit 56,
59, 57 and 58 are provided. These monitoring control units 56 to 59 are a combination of the OSC termination unit and the control circuit described with reference to FIGS. However, in the example shown in FIG. 10, since the main signal is transmitted bidirectionally, the OSC transmitted and received between the monitoring control units is transmitted bidirectionally using optical signals of different wavelengths.

In FIG. 10, optical signals having different wavelengths from each of the plurality of LTEs 50 are W signals in the ET 52.
After being wavelength-multiplexed by the DM 64, the bidirectional optical amplifier 60
After being amplified to a predetermined output level, and then sent out to the relay optical fiber. The wavelength-multiplexed optical signal transmitted in the relay optical fiber is inserted into the LA5
Attenuation in the fiber is compensated by ET5
3 is received. The optical signal received by ET53 is ET53.
After being amplified to a predetermined level by a bidirectional optical amplifier 63 in 53, the wavelength is separated by a WDM 65 and a plurality of LTs
It is sent to E50 '. Similarly, the optical signals from the plurality of LTEs 50 'are transmitted to the plurality of LTEs 50 through the same optical fiber along the reverse path. In the above description, different wavelengths of light are used for transmission in both directions.

Each of the monitoring control units 56 to 59 monitors a failure of a device in the system, a fiber breakage fault, and the like, and transmits and receives an OSC, which is a monitoring optical signal, between devices constituting the system. . Then, each monitoring control unit 5
6 to 59 have a function of temporarily converting a received signal in the OSC into an electric signal to take various interfaces, and transmitting a signal to be transmitted on the OSC and transmitting the signal to an adjacent device.

Each of the monitoring controllers 56 to 59 has a common interface, a house keeping function HK (House Keepin) for inputting / outputting an alarm to / from a floor on which the device is placed.
g), OW which is an analog telephone line for maintenance personnel, SC (S) for communication with other devices by digital signals
and a CI (Craft Interface) for inputting / outputting the status of the system to / from a PC or the like. The monitoring control unit 56 provided in the ET 52 includes:
Interface Transaction Language One Division (TL) for operators to monitor the entire system
1) is provided.

In the example of FIG. 10, for simplicity of illustration, the OS
Although the line through which C passes is drawn separately from the optical fiber through which the main signal passes, in practice, the OSC is also wavelength-multiplexed into the optical fiber through which the main signal passes. This is the same in the following drawings. The OSC for monitoring is separated or multiplexed from the main signal in the device where each monitoring control device is placed. In the system shown in FIG. 10, a maximum of 16 (8 × 2) terminal devices can be provided.

FIG. 11 is a block diagram showing a configuration of an optical transmission system according to another embodiment of the present invention. In FIG. 11, 52 ′ and 53 ′ are ET, 54 ′ and 55 ′ are LA,
Reference numerals 56 'to 59' denote monitoring control devices, 51 denotes a regenerative repeater (LRE: Line Regenerator Equipment), 65 denotes an extended monitoring signal line (EOB: Enhanced OSC BUS), and the other symbols are the same as those in FIG. Are identical.

The system shown in FIG. 10 relays an optical signal as a main signal using an optical amplifier of a wide band without converting it into an electric signal, and is transmitted by an optical fiber of three spans by two LAs. Even when a road is formed, the actual transmission distance cannot be set to 270 km or more.

In another embodiment of the present invention shown in FIG. 11, the transmission distance can be further increased, and the system described with reference to FIG. 10 is configured by connecting two systems in series via an LRE 51. is there. With this configuration, 5
Transmission up to 40 km can be performed. The LRE 51 that connects the two systems has a function of temporarily demodulating the wavelength-multiplexed all optical signal into an electric signal, compensating for the signal degradation or the like in the state of the electric signal, and then putting the signal on the optical signal.

In the configuration shown in FIG.
The 53, 53 'and the LRE 51 are installed in the same station. In the embodiment shown in FIG. 11, it is necessary to manage the entire system according to this embodiment as one system, and an optical fiber that transmits only the OSC is provided between the monitoring control devices 59 and 59 ′ of the ETs 53 and 53 ′. , An extension monitoring signal line EOB65 is provided. Therefore, also in this embodiment, FIG.
Can be monitored for all devices constituting the system shown in FIG.

FIG. 12 is a block diagram showing a configuration of an optical transmission system according to another embodiment of the present invention. This embodiment is configured by installing the system shown in FIG. 10 in parallel with four systems. Therefore, SYSTEM1 to SYM
Since the STEM 4 is configured in exactly the same way as in FIG. 10, each device constituting each system is denoted by the same reference numeral as in FIG. However, for simplicity of illustration, 52, which has been the ET code so far, is replaced by S
It was used as a symbol for the wavelength multiplexing devices of YSTEM1 to SYSTEM4 and the bidirectional optical amplifier unit. Similarly, reference numeral 53
.About.55 are represented as reference numerals of the individual transmission devices except for the monitoring control unit.

The characteristic configuration of this embodiment is that the monitoring control devices 56 to 59 in the SYSTEM 1
And the OSC transmitted and received between them as the active system, and the monitoring control devices 56 to 59 in the SYSTEM 2 are used.
And the OSC transmitted and received between them is used as a spare, and the entire four systems are monitored by these two systems. For this reason, the IOB (Intra site OSC B) is provided between the monitoring control devices 56 and 57 provided in the transmission devices 52 and 53 in the SYSTEMs 1 and 2.
US), and monitoring and control devices 56 to 59 of the devices constituting each system.
Is an ISB (Intrasite BUS) between each other
An electrical connection path is provided. The LA IOB is omitted for simplicity of illustration.

In the system configured as described above, if the active monitoring and control system provided in SYSTEM 1 is operating normally, SYSTEM 2 through SYS
The monitoring control devices 56 to 59 provided in the TEM 4 report the monitoring result of the failure or the like in the own system to the corresponding device of the working system via the ISB by an electric signal, and the transmission of the monitoring information in the main signal direction is performed by the working signal. This is performed by the system monitoring and control system. Also, if the working monitoring and control system provided in the SYSTEM 1 becomes unavailable due to a failure or the like,
The standby supervisory control system provided in SYSTEM 2
The monitoring operation is continued using the OB in place of the active system. The wavelength of the OSC used for the working system and the protection system is the same for each transmission direction.

The above-described embodiment has two working and spare monitoring control systems, so that the reliability of the entire system can be improved, and each system has a complete monitoring and control system. Since it is not necessary to prepare the data, it is possible to reduce the cost.

In the above-described embodiment, four systems are configured in parallel to increase the total signal transmission capacity. However, in this embodiment, two or three systems may be configured in parallel. Also, many more systems may be configured in parallel.

FIG. 13 is a block diagram showing a configuration of an optical transmission system according to another embodiment of the present invention. In this embodiment, the system shown in FIG. 11 is configured by installing four systems in parallel. Therefore, SYSTEM1-SYST
Since each system shown as EM4 is configured exactly the same as in the case of FIG. 11, each device constituting each system is denoted by the same reference numeral as in FIG. However, for the sake of simplicity of illustration, reference numerals 52 to 55 are represented as reference numerals of individual transmission devices excluding the monitoring control unit.

The embodiment shown in FIG. 13 can increase the transmission distance similarly to the embodiment described with reference to FIG. 11, and the system described with reference to FIG.
Four systems are used in which two systems are connected in series via the RE 51. With this configuration, 54
Transmission up to 0 km can be performed. And S
A supervisory control device 59 in two supervisory control systems, an active system and a standby system, provided in YSTEM1 and SYSTEM2;
Only the portions 59 'are connected by the EOB 65.

The embodiment having the above-described configuration has the advantages of the two embodiments described with reference to FIGS. This embodiment is similar to that of FIG.
As described above, two or three systems may be configured in parallel, or a larger number of systems may be configured in parallel.

Next, various configuration examples of the ET and the LA in the system according to the embodiment of the present invention configured as described above will be described.

FIG. 14 is a block diagram showing a configuration example of the ET. This ET configuration example is an ET configuration that handles optical signals of four channels, that is, eight wavelengths in each of the East and West directions. 14, 71 is a wavelength multiplexer, 72 is a wavelength separator, 73 and 77 are transmission characteristic compensators,
74 is a transmitting optical amplifier, 75 is a receiving optical amplifier, 76 is a multiplexer / demultiplexer, 78 is an OSC terminator, and 79 is a power supply device. In the drawings, portions surrounded by thick lines are portions configured as one printed circuit board package in an actual device, and the same applies to other examples described later. Note that a symbol indicated by a lead line in the drawing indicates a signal name monitored at that position. In other words, although not shown for simplicity of illustration, each monitor point is provided with a temperature measuring element, a branch coupler, and a monitoring PD (photodiode). The name of the monitor point, for example, TLTMP attached to the transmission optical amplifier 74 means the pump laser temperature of the transmission optical amplifier. This is common to the following drawings.

The wavelength multiplexer 71 multiplexes optical signals of different wavelengths transmitted from the four LTEs through input terminals indicated as CH1 to CH4 and outputs the multiplexed optical signals to the transmission characteristic compensator 73. The wavelength multiplexer 71 also has a function of adjusting the power of the input optical signal of each wavelength to be balanced. The transmission characteristic compensator 73 is a dispersion compensating fiber (DCF: Disperser) for compensating the transmission characteristic of the relay optical fiber.
It is composed of an optical fiber called an ion compensation fiber. This fiber has a dispersion characteristic with a sign opposite to that of the repeater optical fiber.
However, the transmission characteristic compensator may be another dispersion compensator such as a Bragg grating. Further, another transmission characteristic compensator may be used. Also, as shown in FIG. 22, which will be described in detail later, LTE and wavelength multiplexer 712
There is a 10: 1 optical coupler 713 and an input monitor 714 between the
The ET can automatically detect that there is a TE, and can inform the entire transmission system of this multiplex number information through the OSC.

The optical signal output from the transmission characteristic compensator 73 is amplified to a predetermined level by the transmission optical amplifier 74, then output to the relay optical fiber via the multiplexer / demultiplexer 76, and transmitted to the subsequent LA. Sent. At this time, the transmission optical amplifier 7
Reference numeral 4 uses the information on the number of multiplexed wavelengths detected by the input monitor to automatically control the gain according to the number of multiplexed optical signals, thereby making the optical level per optical signal constant. The multiplexer / demultiplexer 76 has a function of multiplexing the transmission optical signal from the transmission optical amplifier 74 and the monitoring light and outputting the multiplexed signal to the relay fiber, and separates the reception optical signal from the relay fiber and the monitoring light. Function.

The received optical signal split by the multiplexer / demultiplexer 76 is converted into a received optical amplifier 75 composed of two-stage optical amplifiers.
The optical signal is transmitted to the wavelength separator 72 via the optical network, and is separated into optical signals of wavelengths for each LTE and transmitted to LTE. Receive optical amplifier 7
The transmission characteristic compensator 77 is connected between the two-stage optical amplifier 5 and compensates for the characteristics of the received optical signal that fluctuates due to the characteristics of the relay optical fiber.

On the other hand, the OSC transceiver 78 is an optical receiver,
Equipped with optical / electrical converter, optical transmitter, electric / optical converter, etc.
The supervisory information from the supervisory controller 56 is sent to the multiplexer / demultiplexer 76 on the supervisory light, and further transmitted to the LA. Also, the monitoring light is demultiplexed by the multiplexer / demultiplexer 76 from the LA side.
The transceiver 78 receives the demultiplexed monitoring light and outputs the included monitoring information to the monitoring control unit 56 as an electrical signal.

An agent communication function bus (ACFBUS) is provided between the monitoring control unit 56 and the package accommodating the above-described functional units.
The monitoring control unit 56 monitors the level of the optical signal at each monitoring point in the package, and controls the power level of the optical signal in the input / output channel. ing. In addition, the optical power on the input side and the output side of each optical amplifier, wavelength multiplexer, wavelength demultiplexer, and demultiplexer, the drive current of the laser diode for excitation of each optical amplifier, the excitation light power, and the element temperature are: O
Remote monitoring is possible at any site through the SC.

The above-mentioned interface between the monitoring control unit and the package accommodating each functional unit and the reference numerals indicated by balloons are the same in the case of the other drawings described later.
Further, the power supply 79 supplies various types of power having a voltage necessary for operating the above-described respective functional units. The same applies to power supply devices in other devices described below.

FIG. 15 is a block diagram showing a configuration example of the LA. This example of the configuration of the LA is an example of the configuration of the LA that handles optical signals of four channels, that is, eight wavelengths in each of the East direction and the West direction. 15, reference numerals 81 and 82 denote multiplexer / demultiplexers, 83 and 84 denote optical amplifiers, 85 and 86 denote transmission characteristic compensators, 87 and 88 denote OSC termination units, and 89 denotes a power supply device.

In FIG. 15, multiplexers / demultiplexers 81 and 82 are
It has the same function as the multiplexer / demultiplexer 76 described in FIG. The multiplexer / demultiplexer 81 demultiplexes the optical signal from the relay fiber on the side indicated as West in the figure and outputs the demultiplexed optical signal to the optical amplifier 83. The optical amplifier 83 is composed of a two-stage optical amplifier similarly to the reception optical amplifier 75 described with reference to FIG. 14, and a transmission characteristic compensator 85 is connected between them. Therefore, the optical amplifier 83 and the transmission characteristic compensator 85
14 has the same function as the configuration of the receiving optical amplifier 75 and the transmission characteristic compensator 77 in FIG. 14, that is, the transmission characteristic of the relay optical fiber can be compensated. The optical signal whose transmission characteristics have been compensated is output to the East-side optical fiber via the multiplexer / demultiplexer 82.

As described above, the multiplexer / demultiplexer 82 has an Eas
The optical signal from the relay fiber on the side indicated as t is demultiplexed and output to the optical amplifier 84. Optical amplifier 84
Also, the optical amplifier 83 is constituted by a two-stage optical amplifier similarly to the optical amplifier 83, and the transmission characteristic compensator 86 is connected between them, so that the transmission characteristic of the relay optical fiber is compensated and the optical signal from the East side is converted. The signal can be output to the optical fiber on the west side via the multiplexer / demultiplexer 81. The optical amplifiers 83 and 8
4 performs automatic control of a gain according to the number of multiplexed optical signals using information on the number of multiplexed optical signals (number of multiplexed wavelengths) contained in the monitoring light transmitted from the upstream, and keeps the optical level per optical signal constant. To

The LA shown in FIG. 15 is capable of amplifying an optical signal in both directions and relaying while compensating for the transmission characteristics of the relay optical fiber by having the above-described configuration.
The OSC terminating units 87 and 88 correspond to the OS described with reference to FIG.
The OSC termination unit 87 has the same function as the C termination unit 78. The OSC termination unit 87 transmits and receives monitoring light to and from the West-side optical fiber, and the OSC termination unit 88 communicates to and from the East-side optical fiber. Of the monitoring light is transmitted and received.

FIG. 16 is a block diagram showing another configuration example of the ET. This ET configuration example is an ET configuration that handles optical signals of eight channels, that is, 16 wavelengths in each of the East direction and the West direction. In FIG. 16, 70 is an excitation light source, 71 ′ is a wavelength multiplexer, 72 ′ is a wavelength separator,
Other reference numerals are the same as those in FIG.

The ET shown in FIG. 16 has basically the same configuration as the ET described with reference to FIG. In this example, a wavelength multiplexer 71 'and a wavelength separator 72' are added to handle optical signals of eight channels in each of the East direction and the West direction.
The point that the wavelength-multiplexed optical signal from 1 ′ is further multiplexed to the wavelength-multiplexed optical signal by the wavelength multiplexer 71, and that the wavelength-multiplexed optical signal and This is greatly different from the ET configuration described with reference to FIG. 14 in that it is separated into a wavelength multiplexed optical signal to be passed to the device 72 '.

In the ET, optical signals of eight channels, that is, eight different wavelengths, must be multiplexed in the east direction and the west direction and loaded on an optical fiber. Since twice as much optical power is required as in the case of the same four-wavelength multiplexing, pumping light is supplied from the pumping light source 70 to the transmitting optical amplifier 74 and the receiving optical amplifier 75, and the respective amplifiers 74, 75 Is increased.

The ET shown in FIG. 16 is exactly the same as the ET described with reference to FIG. Therefore, further description is omitted here. FIG. 17 is a block diagram showing another configuration example of the LA. This example of the configuration of the LA is an example of the configuration of an LA that handles optical signals of eight channels, that is, 16 wavelengths in the East direction and the West direction, respectively. 17, reference numeral 80 denotes an excitation light source, and other reference numerals are the same as those in FIG.

The LA shown in FIG.
15 except that the excitation light source 80 is supplied from a separate package. The LA amplifies optical signals transmitted through eight channels, that is, optical signals of eight different wavelengths, which are multiplexed in the East direction and the West direction, that is, optical signals having eight different wavelengths, and relays the amplified optical signals by optical amplifiers 83 and 84. As in the case of the ET described with reference to FIG. 16, the pumping light source 80 supplies pumping light to the optical amplifiers 83 and 84 to increase the optical output levels of the amplifiers 83 and 84. I have.

ET and LA described with reference to FIGS.
Is an example in which an optical multiplexed signal is transmitted bidirectionally within one relay optical fiber. Next, relay optical fibers are separately provided in the East direction and the West direction, and each optical fiber is transmitted. E when transmitting an optical signal in which 16 wavelengths are multiplexed in a fiber
Examples of T and LA will be described. FIG. 18 shows a relay optical fiber.
It is a block diagram which shows the example of a structure of ET when separately provided in East direction and West direction. In FIG. 18, 70 'is an excitation light source, 91 is a wavelength multiplexer, 92 is a wavelength separator, 93 and 94.
Denotes a multiplexer / demultiplexer, and other symbols are the same as those in FIG.

The configuration example of the ET shown in FIG. 18 has a configuration corresponding to the fact that the relay optical fibers are separately provided in the East direction and the West direction. The basic configuration will be described with reference to FIG. This is the same as the configuration of the ET. That is, in FIG. 18, optical signals of each of the 16 wavelengths from a terminal device (not shown) are multiplexed by a wavelength multiplexer 91 which multiplexes 16 wavelengths via an input monitor (not shown) provided in an input interface unit. At this time, the ET can automatically detect that there is an unused or failed LTE,
This wavelength multiplex number information can be notified to the entire transmission system through the OSC. The output light of the wavelength multiplexer 91 is
The signal is input to the transmission optical amplifier 74 via the transmission characteristic compensator 73. The transmission light amplifier 74 has a pump light source 70 added thereto, and is controlled so that the output optical power becomes a predetermined magnitude. In detail, the transmission optical amplifier 74 performs automatic control of the gain according to the number of multiplexed optical signals using information on the number of multiplexed optical signals (number of multiplexed wavelengths) detected by the input monitor, and adjusts the optical level per optical signal. Keep it constant. Transmit optical amplifier 74
Is output from the OSC transceiver 7 by the multiplexer / demultiplexer 93.
The transmission light is multiplexed with the monitoring light from No. 8 and transmitted to the relay optical fiber on the transmission side.

On the other hand, the optical signal from the relay optical fiber on the receiving side is separated from the monitoring light by the multiplexer / demultiplexer 94, and the monitoring light is input to the OSC transceiver 78. The main signal in which 16 wavelengths are multiplexed has its transmission characteristics compensated for by a transmission characteristics compensator 77 and a wavelength separator 75 through a reception optical amplifier 75 whose optical output is controlled by an excitation light source 70 '. 92. The wavelength separator 92 separates the multiplexed optical signal into optical signals having 16 wavelengths and transmits the optical signal to a terminal device (not shown) via an output interface. Here, the reception optical amplifier 75 performs automatic control of a gain according to the number of multiplexed optical signals using information on the number of multiplexed optical signals (number of multiplexed wavelengths) contained in the monitoring light transmitted from the upstream, and Make the light level per hit constant.

FIG. 19 shows the relay optical fiber in the East direction,
It is a block diagram which shows the example of a structure of LA when separately provided in st direction. In FIG. 19, 95, 95 ', 96, 96'
Denotes a multiplexer / demultiplexer, 97 and 98 denote excitation light sources, and other symbols are the same as those in FIG.

The configuration example of the LA shown in FIG. 19 has a configuration corresponding to that the relay optical fibers are separately provided in the East direction and the West direction, and the basic configuration is as follows.
This is the same as the configuration of the LA described with reference to FIG. That is, in FIG. 19, an input optical signal from the optical fiber on the west side is separated into monitoring light by the multiplexer / demultiplexer 95, and the monitoring light is input to the OSC transceiver 87. The transmission characteristics of the main signal multiplexed with 16 wavelengths are compensated for by the transmission characteristic compensator 85, and the multiplexer / demultiplexer 96 is transmitted via the optical amplifier 83 whose optical output is controlled by the pumping light source 97. Is input to Here, the optical amplifier 83 uses the wavelength multiplex number information included in the monitoring light transmitted from the upstream to automatically control the gain according to the number of wavelength multiplexes, and keeps the light level per wavelength constant. The multiplexer / demultiplexer 96 multiplexes the multiplexed optical signal from the optical amplifier 83 with the monitoring light from the OSC transceiver 88 and transmits the multiplexed optical signal to the East-side relay optical fiber. Similarly, the input optical signal from the East-side relay optical fiber is supplied to the multiplexer / demultiplexer 95 ′, the optical amplifier 84, and the multiplexer / demultiplexer 9.
The signal is transmitted to the optical fiber on the West side via 6 '.

ET and L described with reference to FIGS.
A can monitor the optical signal level (optical power) of each of the functional units constituting the ET and LA via the ACFBUS by the monitoring control unit, and can adjust the level of the optical signal. First, control of the channel optical input power, which is the optical power of each of the optical signals of a plurality of wavelengths transmitted from a plurality of terminal devices, will be described.

The adjustment of the channel light input power is necessary for the adjustment at the time of the construction of the equipment and the compensation for the light level deterioration due to the lapse of time after the construction. The adjustment of the channel light input power is performed in the ET provided with the wavelength multiplexer. The adjustment at the time of construction of the equipment is performed, for example, as follows. First, monitor light is extracted from an optical monitor point provided on the output side of the transmission optical amplifier 74 shown in FIG. 14, and is analyzed by an optical spectrum analyzer or the like, and the optical signal level of each wavelength is displayed. Then, the power of the optical signal of each wavelength for each channel in the output of the transmission optical amplifier 74 is balanced, and the level of the optical signal of each wavelength from the transmission optical amplifier 74 becomes a predetermined level. Next, the light intensity adjuster provided in the wavelength multiplexer 71 is controlled from a control terminal connected to the monitoring control unit 56.

Thus, the multiplexed transmission optical signal can be set to an optimum state. When the above-described adjustment is once performed, the monitoring control unit 56 automatically feeds back the information by storing the adjustment amount and the set level in a non-volatile memory or the like for each channel. In addition, compensation for a decrease in the light level due to deterioration with time of the transmission light source can be performed at any time. This makes it possible to always maintain a predetermined transmission output independently for each channel, regardless of which lot is used as the transmission optical amplifier 74, and to achieve uniform transmission quality. . Hereinafter, this will be described with reference to FIGS.

FIG. 20 is a diagram for explaining control for adjusting the optical power of the optical signal transmitted from a plurality of terminal devices using the monitor output of the optical amplifier of the ET. Hereinafter, FIG.
The details of the variable control of the channel optical input power which is the optical power of each of the optical signals of a plurality of wavelengths transmitted from the plurality of terminal devices will be described with reference to FIG.

FIG. 20 shows a wavelength multiplexing unit 71 comprising an optical adjuster 711 and a wavelength multiplexer 712 for adjusting the signal levels of a plurality of wavelength signals transmitted from a terminal equipment (not shown), and a transmission characteristic adjusting unit 73. And the transmission optical amplifier 74
, An ET including a monitoring control unit 56, a spectrum analyzer 100, and a control terminal 200 are illustrated. Here, the monitor port 99 of the transmission optical amplifier 74
Is connected to the spectrum analyzer 100, and the control terminal 200 is connected to the craft interface of the monitoring control unit 56. Further, the spectrum analyzer 100 and the control terminal 200 are connected by a GP-IB interface.

With this configuration, the transmission characteristic compensator 73
Then, the optical power of each wavelength after passing through the transmission optical amplifier 74 can be monitored. Then, by feeding back the result to the light intensity controller 711 of the wavelength multiplexing unit 71, control can be performed so as to eliminate the deviation between the wavelengths. When actually transmitting a signal, the feedback system may be used for control. Further, the measurement result may be written in a nonvolatile memory as a reference voltage of a feedback system of the light intensity adjuster 711 described later and controlled. As a result of these controls, even if the transmission light source provided in the terminal device deteriorates with time and the power level of light decreases, the light intensity adjuster 711 can compensate for this.

FIG. 21 is a diagram for explaining control for adjusting the optical power of the optical signal transmitted from a plurality of terminal devices using the monitor output of the optical amplifier of the LA. FIG.
Is a configuration in which an LA composed of a relay optical amplifier 83 and a monitoring information control unit 57 is added to the configuration shown in FIG. Here, for simplicity of illustration, the transmission characteristic compensator provided in the ET and the LA is omitted. However, the spectrum analyzer 100 is connected to the monitor port 9 of the relay optical amplifier 83.
Connect to 9 '. Further, the control terminal 200 is connected to the craft interface of the monitoring control unit 57. The monitoring controller 57 is connected to the monitoring controller 56 using the OSC, so that the light controller 711 can be controlled from the control terminal 200.

With this configuration, the LA repeater optical amplifier 8
The optical power of each wavelength after passing through 3 can be monitored. Then, by feeding back the result to the light intensity controller 711 of the wavelength multiplexing unit 71, control can be performed so as to eliminate the deviation between the wavelengths. This feedback system may be used at all times, or the light intensity adjuster 71 may be used.
As in the embodiment of FIG. 20, the control may be performed by writing to the first memory.

It will be apparent that control is possible using the monitor output of the receiving optical amplifier. Although the above-described embodiment has been described assuming one-way transmission for convenience, it will be apparent that the present invention can also be applied to two-way transmission. According to this embodiment, it is possible to control the multiplexed transmission optical signal described above in an optimal state, that is, to control the optical power of each wavelength to be balanced. The power of the optical signal of each wavelength to be transmitted can be made uniform.

This control includes automatic adjustment of the power of the optical input signal in each input channel at the time of system construction, adjustment of maintenance personnel intervention by setting the amount of attenuation in the LC at the time of construction, and devices constituting the system during system operation. This can be used for adjustment for compensating for the light level deterioration of the light source.

As described above, the power of the optical signal of each wavelength for each channel at the output of the transmission optical amplifier 74 is balanced and the transmission optical amplifier 7
The optical intensity adjuster provided in the wavelength multiplexer 71 is controlled from an external control terminal connected to the monitoring and control unit so that the level of the optical signal of each wavelength from 4 becomes a predetermined level. This allows the user or local installer to
It becomes possible to easily set the channel light input power via an external terminal.

Further, by holding the set amount in the system as described above, automatic control can be performed so that the set value is maintained even after the operation. That is, ET is
Even in a state where the external terminal and the measuring device are detached, appropriate automatic adjustment can be performed for the ET alone. As described above, the ET according to the embodiment of the present invention can collectively set and manage transmission signal powers of a plurality of wavelengths in accordance with an actual system. Also, unlike a general optical attenuator, an optical intensity adjuster can adjust an optical gain without necessarily attenuating light, maintain a predetermined optical transmission power, and improve optical transmission quality. Is effective in maintaining and managing

Next, the configuration of the light intensity adjuster will be described with reference to FIGS. 22 and 23. Here, FIG. 22 is a diagram for explaining control of a light intensity adjuster provided between the plurality of terminal devices and the optical multiplexer. FIG. 23 is a diagram illustrating the output of the terminal device, the output of the optical intensity adjuster, and the output of the optical multiplexer in comparison. FIG. 22 illustrates the light intensity adjuster described with reference to FIGS. 20 and 21 in more detail, and illustrates one wavelength of the ET wavelength multiplexing unit 71 of FIG. The optical signal from the terminal device is transmitted to the optical coupler 7.
At 13, a part of the light is monitored by the input PD 714. Most of the optical signals are amplified by the optical intensity adjuster 711, passed through the coupler 715, and multiplexed with other wavelengths by the wavelength multiplexer 712. The optical signal partially branched by the coupler 715 becomes an electric signal at the PD 716, is compared with the reference voltage 718 by the differential amplifier 717, and is fed back to the light intensity adjuster 711 by the light intensity adjuster control unit 719. In the embodiment described with reference to FIGS. 20 and 21,
The control is performed by dynamically changing the reference voltage or writing the value in a memory for generating the reference voltage 718. The above-described light intensity adjuster 711 may be considered as a small optical amplifier. That is, the controller 71
Reference numeral 9 controls the excitation power of the small optical amplifier.
However, since this light intensity adjuster does not require a large excitation power, it is inexpensive and does not need to consider cooling or the like.

FIG. 23 shows a signal level diagram of each part in FIG. At the entrance of the wavelength multiplexing unit, the output level of the transmission light source of the terminal station device is obtained, and the light intensity adjuster can adjust the output level up to 10 dB. After passing through the wavelength multiplexer, the loss is 7 dB to 13 dB.
Suffer loss. In adjusting the signal level with the attenuator,
In the initial setting, a large amount of attenuation must be set, which affects the transmission distance.However, since the light intensity regulator of this embodiment amplifies light, it is possible to obtain a long transmission distance from the initial setting state. it can. Further, this light intensity adjuster is effective in maintaining a predetermined light transmission power and maintaining and managing the optical transmission quality.

In the optical transmission system described above, it is necessary to control the power of the transmission optical signal of each wavelength within a predetermined range in order to maintain the signal transmission quality of each wavelength. For this reason, the above-described optical transmission system can control the output to the relay optical fiber to be constant, thereby suppressing the fluctuation of the optical loss occurring in each transmission span and transmitting it to the next transmission span. Become. Therefore, the adjustment of the optical signal level of each wavelength in the wavelength multiplexer is important.

The transmission characteristic compensator provided in the ET and LA compensates for the transmission characteristic in the relay optical fiber. However, in order to suppress the nonlinear effect in the transmission characteristic compensator, the transmission characteristic compensator is used. It is necessary to keep the optical power per channel input to the device below a predetermined value, and conversely,
In order to suppress deterioration of the signal SN due to optical loss in the transmission characteristic compensator, the optical power per channel input to the transmission characteristic compensator needs to be large to some extent. The ET and LA described above are configured so that this condition is satisfied by adjusting the amplification degree of the optical amplifier preceding the transmission characteristic compensator. As a result, the above-described ET and LA can suppress the nonlinear effect by the transmission characteristic compensator, prevent the signal SN from deteriorating, and improve the transmission quality of the optical signal.

ET and LA described with reference to FIGS.
Supplies excitation light from the excitation light source to the optical amplifier,
The level of the optical output of the optical amplifier is increased. Next, this control will be described.

For example, in the ET shown in FIG. 18, the supervisory control unit 56 detects the optical power of the input optical signal of each channel at the input interface of the wavelength multiplexer 91 by using an optical input detector, and when the optical power is higher than a predetermined optical power. A certain channel is recognized as a transmission channel, a channel having a predetermined optical power or less is recognized as a non-transmission channel, the number of transmission channels is counted, and the counted number is treated as the number of wavelengths. The optical power is controlled and supplied to the optical amplifier 74. Thus, the level (power) of the optical output of the optical amplifier 74 can be controlled. This wavelength number information is superimposed on the monitoring light and transmitted one after another to the downstream LA, LRE, etc., and can be used for controlling those optical amplifiers.

As described above, in the wavelength division multiplex transmission system of the present invention, the number of wavelengths can be counted. Therefore, there is no need to obtain information from the optical transmitter. That is, the wavelength division multiplexing transmission system of the present invention is an independent system without depending on the optical transmitter.

Such control of the optical amplifier is effective for maintaining the output power of the optical signal of each wavelength from each optical amplifier at a predetermined level without changing according to the number of multiplexed wavelengths. is there. Generally, an optical amplifier has a problem that the optical output of all channels (total) is controlled to be a predetermined value, and the output level of an optical signal for each wavelength fluctuates when the number of wavelength multiplexes changes. But
By performing control based on the wavelength number information as described above, the output level of each wavelength can be controlled to a predetermined magnitude.

[0104]

As described above, according to the present invention, even when a plurality of optical transmission systems are operated in series or in parallel, the system can be monitored efficiently and cost can be reduced. It is possible to provide an optical transmission system capable of reducing power consumption and a monitoring method thereof.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating various configurations of an optical transmission system that transmits a wavelength multiplexed optical signal using a wavelength division multiplexing / demultiplexing device.

FIG. 2 is a diagram illustrating a monitoring method for transmitting failure information including a failure location to an end terminal using monitoring light.

FIG. 3 is a diagram illustrating a monitoring method for transmitting failure information including a failure location to an end terminal using monitoring light.

FIG. 4 is a diagram illustrating a monitoring method for transmitting fault information including a fault location to an end terminal using monitoring light.

FIG. 5 is a diagram illustrating a monitoring method for transmitting failure information including a failure location to an end terminal using monitoring light.

FIG. 6 is a diagram illustrating a monitoring method for transmitting fault information including a fault location to an end terminal using monitoring light.

FIG. 7 is a block diagram illustrating an outline of a configuration example of an optical transmission system in the case of one system.

FIG. 8 is a block diagram illustrating an outline of a configuration example of a parallel optical transmission system in which two systems are provided in parallel.

FIG. 9 is a diagram for explaining a method of OSC function division.

FIG. 10 is a block diagram illustrating a configuration of an optical transmission system according to the first embodiment of the present invention.

FIG. 11 is a block diagram illustrating a configuration of an optical transmission system according to a second embodiment of the present invention.

FIG. 12 is a block diagram illustrating a configuration of an optical transmission system according to a third embodiment of the present invention.

FIG. 13 is a block diagram illustrating a configuration of an optical transmission system according to a fourth embodiment of the present invention.

FIG. 14 is a block diagram illustrating a configuration example of an ET.

FIG. 15 is a block diagram illustrating a configuration example of an LA.

FIG. 16 is a block diagram showing another configuration example of the ET.

FIG. 17 is a block diagram illustrating another configuration example of the LA.

FIG. 18 is a block diagram illustrating a configuration example of an ET in a case where relay optical fibers are separately provided in a vertical direction.

FIG. 19 is a block diagram illustrating a configuration example of an LA in a case where relay optical fibers are separately provided in a vertical direction.

FIG. 20 is a diagram illustrating control for adjusting the optical power of the optical signal transmitted from a plurality of terminal devices using the monitor output of the ET optical amplifier.

FIG. 21 is a diagram illustrating control for adjusting the optical power of the optical signal transmitted from a plurality of terminal devices using the monitor output of the optical amplifier of the LA.

FIG. 22 is a diagram illustrating control of a light intensity adjuster provided between a plurality of terminal devices and an optical multiplexer.

FIG. 23 shows the output of the terminal device, the output of the light intensity adjuster,
FIG. 4 is a diagram for explaining an output by comparing with an output of an optical multiplexer.

FIG. 24 shows an OC-3 in which an information transfer function between devices is embedded.
FIG. 4 is a diagram showing an overhead part of FIG.

FIG. 25 is a diagram illustrating bit allocation of an AIS byte.

[Explanation of symbols]

21, 24, 62, 63 ... wavelength division multiplexer (WD)
M), 22, 23, 25, 26, 83, 84... Optical amplifiers, 21, 24, 62, 63.
M), 22, 23 ... optical amplifier (LA), 25, 26, 83, 84 ... optical amplifier (LA), 27, 28 to 33, 40 to 46 ... OSC function unit, 34 to 39 ... selector (SEL), 50, 51: Terminal equipment (LTE), 52, 53: End terminal (ET), 54, 55: Bidirectional optical repeater (LA), 56-59: Monitoring and control unit, 60, 61: Bidirectional optical amplifier 64, a regenerative repeater (LRE), 65, an extension monitoring signal line (EOB), 71, 91, a wavelength multiplexer, 72, 92, a wavelength separator, 73, 77, a transmission characteristic compensator, 74, a transmission light Amplifier, 75: Receive optical amplifier, 76, 81, 82, 93, 94, 95, 96: Multiplexer / demultiplexer, 78, 87, 88: OSC transceiver, 79, 89: Power supply device, 85, 86: Transmission characteristics Compensator, 70, 80, 97, 98 ... Cause light source.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H04B 10/02 (72) Inventor Takayuki Suzuki 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture, Hitachi, Ltd. Information and Communications Department (72 ) Inventor Kenro Sekine 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. ) Inventor Takashi Mori 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref.Hitachi Ltd.Information and Communication Division, Hitachi Ltd.

Claims (4)

[Claims] 1. An optical transmission system for transmitting a plurality of optical main signals, the optical transmission system comprising a plurality of optical transmission subsystems arranged in parallel for transmitting one of the plurality of optical main signals. Wherein the plurality of optical transmission subsystems each have a supervisory control unit, two of the plurality of optical transmission subsystems each have an optical supervisory signal transmission unit, and one of the optical supervisory signal processing units An optical transmission system for transmitting monitoring information of the plurality of optical transmission subsystems as an active system and another as a maintenance system. 2. An optical transmission system for transmitting an optical main signal, comprising: a first optical transmission subsystem including a first optical supervisory signal transmitting unit for transmitting an optical supervisory signal; and transmitting the optical supervisory signal. A second optical transmission subsystem including a second optical supervisory signal transmission unit; a regenerative repeater for regenerating and repeating the optical main signal; a first optical supervisory signal transmission unit and the second optical supervisory signal transmission And an optical fiber for transmitting the optical monitoring signal, wherein the first optical transmission subsystem, the regenerative repeater,
An optical transmission system, wherein the optical transmission system is connected in series with the second optical transmission subsystem. 3. A method of monitoring an optical transmission system in which a plurality of optical transmission subsystems are arranged in parallel to transmit a plurality of optical main signals, wherein each of the plurality of optical transmission subsystems includes a monitoring control unit. Two of the plurality of optical transmission subsystems each have an optical supervisory signal processing unit, one of the optical supervisory signal processing units is an active system, and the other is a maintenance system, Monitoring the plurality of optical transmission subsystems; multiplexing the monitoring information of the plurality of optical transmission subsystems into one of the plurality of optical main signals; transmitting the multiplexed optical signal A method for monitoring an optical transmission system, comprising: 4. The optical transmission system according to claim 3, wherein the monitoring information of the optical transmission system is described in an overhead section of a frame format.