JPH1013356A - Wavelength multiple optical transmitting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength multiple optical transmitting system capable of easily corresponding to executed ADM node addition and transmission capacitance expansion and of effectively using channels and the band of ADM nodes. SOLUTION: The transmitting system executes light transmission through the use of light with wave lengths different for every channel and the light is transmitted to a transmission path (L) by optically multiplexing the plural channels. The plural ADM nodes 13-1 to 13-3 having a function for branching and inserting (Add/Drop Multiplexer; ADM) one channel (ch) from the plural channels which are wave length-multiplexed and transmitted are provided in the midst of L. The specified ch among the chs is branched and processed in the respective ADM nodes, and is added to the specified ch again and inserted to the L. In this case, a means 13-2 where another ch except the specified ch is branched by the ADM node, processed, added to another ch again and returned to the L and also a signal given to the ADM node at a self downstream side is added to the specified ch and inserted to L is provided for the ADM node among the ADM nodes, where transmission capacitance expansion is required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical communication technology, and more particularly to wavelength division multiplexing (Wavelength Division Multipexin).
g: WDM) technology.

[0002]

2. Description of the Related Art In the field of communication technology, in recent years, with the progress of optical fiber amplifiers, research on long-distance and large-capacity optical transmission systems has been actively conducted, and information transmission systems for realizing the future multimedia information age. It is attracting attention.

[0003] In particular, add / drop multiplexer (AD)
An optical transmission system including an ADM node, which is a node having an M) function, is expected to serve as a lightwave network because it can effectively utilize the broadband and large capacity of an optical fiber. The ADM node has a function of once branching a signal transmitted through the transmission path into its own node and taking it in, and adding a transmission signal from the own node as necessary and sending it out again into the transmission path. Node.

[0004] In optical transmission, as a signal multiplexing method for realizing a large capacity, time division multiplexing (Time Domain multiplexing) is known.
Multiplexing (TDM) and Wavelength Division M
ultip1exing: WDM). Of these, time division multiplexing (TDM) is a method of multiplexing signals in the time domain,
This time division multiplexing optical transmission system has a problem in that the transmission capacity is expandable. That is, in the time-division multiplexing optical transmission system, the ADM node handles all of the transmission signals in the transmission path for the purpose of dropping / inserting, so that the optical transmitting terminal, the optical receiving terminal, and the transmission All ADM nodes on the road are required to have a wide bandwidth that satisfies the transmission capacity. Therefore, in the case where the transmission capacity is insufficient in the time division multiplexing optical transmission system, when it is necessary to increase the capacity, all the ADM nodes must be replaced with transmission apparatuses that satisfy the transmission capacity.

On the other hand, in wavelength division multiplexing (WDM), the transmission capacity of the entire system can be increased by multiplexing optical signals in the wavelength region without increasing the transmission capacity per channel. That is, in the existing wavelength transmission optical transmission system, when it is desired to increase the transmission capacity between arbitrary ADM nodes or the entire transmission system, most of the transmission devices and peripheral devices of each ADM node, optical transmission terminal station, and optical reception terminal station Can be dealt with simply by adding a transmission device and a peripheral device for a channel to be newly multiplexed in the wavelength region without replacing.

[0006] However, the wavelength division multiplexing optical transmission system conventionally assumed to have a fixed configuration is to selectively connect to separate paths for each channel.
FIG. 6 shows a configuration example of a transmission line including an ADM node of a wavelength multiplexing optical transmission system that is assumed to be conventionally fixed.

[0007] Explaining this assumed technology, consider a configuration in which some ADM nodes 103-1 to 103-3 are provided on an optical fiber transmission line 14 which is a transmission line using an optical fiber. In the optical fiber transmission line 14, optical signals 30-1 to 30-8 having different wavelengths are wavelength-multiplexed,
1 to 103-3. In the ADM system of the channels at the ADM nodes 103-1 to 103-3 in the conventional assumed technology, for example, the ADM node 103-1 splits the optical signal 30-1 by wavelength selection, and transmits the signal to the ADM node 103-1.
Optical signals 30-4, 30-5 according to the wavelength selectivity of 3-2 and 103-3
Is inserted and transmitted.

That is, an optical signal having a different wavelength is used for transmission in each of a plurality of channels. The optical signal of each channel is multiplexed and transmitted to the optical fiber transmission line 14. Each of the plurality of ADM nodes provided in the optical fiber transmission line 14 is configured to select a multiplexed optical signal having a different wavelength from each other.

Then, an optical signal having a wavelength used for transmission in a certain channel is branched from the optical fiber transmission line 14 by the ADM node 103-1 by wavelength selection. The ADM node 103-1 captures an optical signal of a specific channel obtained by branching by this wavelength selection,
If there is transmission information to the destination ADM nodes 103-2 and 103-3, the transmission information is transmitted to those ADM nodes 103-2 and 103-2.
, 103-3, and converts the signal into an optical signal of that wavelength and transmits it to the optical fiber transmission line 14.

As described above, the wavelength multiplexing optical transmission system assumed conventionally has a configuration in which optical signals of different wavelengths are used for each channel.
This can be accommodated if the number of channels can be increased, that is, optical signals of different wavelengths can be added. However, for that purpose, it is necessary to add a processing system for processing the added wavelength at the transmitting / receiving terminal station and each node, which is not easy, and another ADM node is newly inserted into the optical fiber transmission line. In this case, it is necessary to change the wavelength selectivity of each ADM node or to add a wavelength for a new channel. Therefore, it is necessary to rearrange the routes in a complicated manner, and the ADM nodes 103-1 to 103-3 need to change the routes. There has been a problem that many additions and rearrangements of subsystems are required.

[0011]

As described above, in a wavelength multiplexing optical transmission system as a conventional assumed technology, when the transmission capacity is increased or a new ADM node is installed, addition of a channel and rearrangement of a channel route are performed. Had to be done in a complicated manner and lacked flexibility. Even if there is an ADM node that requires a small transmission capacity, the channel and the ADM node are provided in the conventional method so that one channel is uniquely provided between the ADM nodes. Bandwidth cannot be used effectively.

An object of the present invention is to provide a first ADM node having a function of dropping / inserting two or more channels and exchanging signals between the channels.
When increasing the signal capacity of the DM node
An object of the present invention is to provide a wavelength division multiplexing optical transmission system which does not require the addition of a subsystem to an ADM node located downstream, by only adding a subsystem at that node.

It is another object of the present invention to provide a first ADM node having a function of exchanging signals between channels, wherein the second ADM node is provided behind the first ADM node.
Wavelength multiplexing that can effectively use the bands of the first channel and the second ADM node by not inserting a signal that is not dropped by the second ADM node into the first channel that is dropped and inserted by the ADM node. An object of the present invention is to provide an optical transmission system.

Still another object of the present invention is to provide a first ADM node having a function of exchanging signals between an optical transmitting terminal and a channel, wherein the first ADM node has a function other than the first ADM node.
The second ADM node has a second A
An object of the present invention is to provide a wavelength-division multiplexing optical transmission system that can effectively use channels and bands of all ADM nodes over the entire transmission path by not inserting a signal that does not branch at a DM node.

[0015]

In order to achieve the above object, the present invention is configured as follows. That is, the first is optical transmission using light of a different wavelength for each channel, in which a plurality of channels are optically multiplexed and transmitted through a transmission path, and the transmission path is wavelength-multiplexed in the transmission path. A plurality of ADM nodes having a function of dropping / adding (Add / Drop Multiplexer: ADM) one channel from a plurality of channels transmitted after transmission are provided, and a specific channel among the channels is provided by each ADM node. In a transmission system in which the signal is branched, processed, and added back to the specific channel and returned to the transmission path, among the ADM nodes, the ADM node that needs to increase the transmission capacity is provided with another channel other than the specific channel. The data is branched and processed by the ADM node, added to the other channel again, returned to the transmission path, and passed to the ADM node on the downstream side of the own node. There signal is characterized in that a means for returning the transmission path in addition to the specific channel.

As described above, in the optical transmission in which light of different wavelengths is used for each channel, a plurality of channels are optically multiplexed, and the transmission path is transmitted, a plurality of ADM nodes are provided on the transmission path, and Among the ADM nodes, the specific channel is processed by branching at each ADM node, and is added back to the specific channel and returned to the transmission path.
The ADM node branches and processes another channel other than the specific channel at the ADM node, adds it to the other channel again, returns it to the transmission path, and transmits a signal to be passed to its own downstream ADM node. Since the signal is added to the specific channel and returned to the transmission path, when the signal capacity to be dropped / inserted at a specific node is increased, the addition of only the subsystem at that node has no effect on the downstream ADM node. Without increasing the signal capacity.

Therefore, when the signal capacity of a desired ADM node is increased, it is not necessary to rearrange the subsystems of other ADM nodes at all, but only by rearranging the subsystems of the ADM node that need to increase the signal capacity. For example, the capacity of an arbitrary ADM node can be easily expanded.

A wavelength division multiplexing optical transmission system according to the present invention comprises: an optical transmission terminal for transmitting a wavelength multiplexed optical signal; an optical reception terminal for receiving a wavelength multiplexed optical signal; It is provided in the middle of a transmission line connecting the terminal station, and is used for wavelength division multiplexing.
Add / Drop Multiplexer: AD
M), and one or more second ADM nodes for dropping / inserting two or more channels, respectively, and the second ADM node is disposed downstream from the first ADM node. A signal that does not branch in the first ADM node is provided with a switching unit that inserts the signal into the second channel.

In such a configuration, the second ADM node is located on the downstream side of the first ADM node.
A signal that does not branch at the M node is inserted into a second channel that does not branch at the first ADM node. Therefore, when the first ADM node exists on the downstream side, the first ADM node on the downstream side Since unnecessary information does not need to be branched, the transmission efficiency can be increased and the bandwidth of the second ADM node can be used effectively.

Further, in the wavelength division multiplexing optical transmission system according to the present invention, in the first ADM node having an optical transmitting terminal and a function of dropping / adding two or more channels and exchanging signals between the channels, Second ADM other than
A signal that does not branch at the second ADM node is inserted into a second channel that does not branch at the second ADM node. This makes it possible to effectively use the channels and the bands of all ADM nodes over the entire transmission path.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, specific examples of the present invention will be described.
This will be described with reference to the drawings. [Basic Configuration as Specific Example] FIG. 1 shows a first embodiment of the first invention.
FIG. 4 is a configuration diagram showing a specific example of the above. In the figure, 100 is an optical transmitting terminal, 102 is an optical receiving terminal, 14 is an optical fiber transmission line, 10
1-1 to 101-3 are first to third ADM nodes.

An optical transmitting terminal 100, which is an optical signal transmitting station, and an optical receiving terminal 102, which is an optical signal receiving station, are connected by an optical fiber transmission line 14, and the optical transmitting terminal 100 has a plurality of channels. Are configured to wavelength multiplex optical signals having different wavelengths in the respective channels and to transmit the multiplexed optical signals to the optical fiber transmission line 14. Further, the optical receiving terminal station 102 has a function of separating a wavelength-division multiplexed optical signal received via the optical fiber transmission line 14 for each wavelength and converting it into a signal for each channel.

The first to third ADM nodes 101-1
101-3 are provided with a function of splitting a transmission channel, inserting required information, and exchanging signals between the channels. The optical link between the optical transmitting terminal station 100 and the optical receiving terminal station 102 is provided. These ADM nodes 101-1 to 101-3 are connected at some positions along the fiber transmission line 14.

The optical transmitting terminal 100 includes optical transmitters 1-1 to 1-4 for each channel, a multiplexer 10, an optical fiber amplifier 12b, and the like. The first ADM node 101-1 is a multiplexer.
10, a duplexer 11, optical fiber amplifiers 12a and 12b, a cross-connect 13-1, an optical receiver 20-1, an optical transmitter 21-1, and the like, and a second ADM node 101-2. Is a multiplexer
10, a duplexer 11, optical fiber amplifiers 12a and 12b, a cross connect 13-2, an optical receiver 20-2a, an optical transmitter 21-2a, and the like.

The third ADM node 101-3 includes a multiplexer 10,
It includes a duplexer 11, optical fiber amplifiers 12a and 12b, a cross connect 13-3, an optical receiver 20-3, an optical transmitter 21-3, and the like. The optical receiving terminal station 102 includes a duplexer 11, an optical fiber amplifier 12a, optical receivers 2-1 to 2-4, and the like.

In this example, the optical transmitting terminal 100 is the channel C-
A total of four communication channels 1 to C-4 are provided, and these channels C-1 to C-4 are configured to use optical signals of different wavelengths for each channel.

In the optical transmission terminal station 100, the signals S-1 to S-4 of the channels C-1 to C-4, which are communication channels, are transmitted by the optical transmitters 1 to 4, which are optical transmitters prepared for the respective channels. The signals are converted into optical signals of different wavelengths by 1 to 1-4 and transmitted. The transmission signals S-1 to S-4 of the respective channels converted into optical signals are wavelength-multiplexed by a multiplexer 10 which is a device for wavelength multiplexing, and are converted into wavelength-multiplexed optical signals, and then output to an output amplification stage. After passing through the optical fiber amplifier 12b and being optically amplified there, the ADM nodes 101-1 to 101-3 and the optical receiving terminal 102 are transmitted through the optical fiber transmission line 14, which is a transmission line.
Transmitted to

At the optical receiving terminal station 102, the wavelength multiplexed optical signal transmitted via the optical fiber transmission line 14 is optically amplified by an optical fiber amplifier 12a which is an amplifier of the optical signal.
The optical receivers 2-1 to 2-1 to 2 are demultiplexed for each wavelength by a demultiplexer 11, which is a means for dividing by wavelength, according to each channel.
Give to 2-4. Optical receivers 2-1 to 2- provided for each channel
In 4, the optical signal for the own channel input after being demultiplexed is received and converted into an electric signal to obtain received signals SR- 1 to SR- 4.

The first to third ADM nodes 101-1
101-3 are provided with optical fiber amplifiers 12a and 12b respectively on the input side and output side for optical loss compensation, and the wavelength multiplexed optical signal transmitted through the optical fiber transmission line 14 is input side. The optical multiplexed optical signal is amplified by the optical fiber amplifier 12a and input to the demultiplexer 11, and the wavelength multiplexed optical signal multiplexed by the multiplexer 10 is converted into an optical fiber amplifier 12b provided on the output side.
And outputs the amplified signal to the optical fiber transmission line 14 on the downstream side. The wavelength-division multiplexed optical signal amplified by the input-side optical fiber amplifier 12a is demultiplexed by the demultiplexer 11, which demultiplexes each wavelength, and divided into optical signals for respective channels. , And the optical signal of the fourth channel is received by the optical receiver. That is, the first ADM node 101-1 uses the optical receiver 20-1 and the second ADM node 101-2 uses the optical receiver 20-1.
In the third ADM node 101-3, the optical receiver 20-3 receives the optical signal of the fourth channel and converts it into an electric signal. The second ADM node 101-2 has an optical receiver 20-2b in addition to the optical receiver 20-2a, and the third ADM node 101-3 has an optical receiver 20-2b. The signal is received by the device 20-3 and converted into an electric signal.

In each of the ADM nodes 101-1 to 101-3, an optical receiver for receiving the signal of the fourth channel branched from the split channel and converting it into an electric signal by the self-built-in splitter 11 is provided. 20-1, 20-2a, and 20-3, and converts the electric signals, which are the conversion outputs of the corresponding optical receivers 20-1, 20-2a, and 20-3, into each of the ADM nodes 101-1 to 101-1. In -3, the configuration is given to the self-built-in cross-connects 13-1, 13-2, 13-3, respectively. Cross Connect 13-1, 13-2, 13-3
Are branch signals SD-1 to SD-3, which are branch signals of the fourth channel given from the corresponding optical receivers 20-1, 20-2a, and 20-3.
This is for exchanging insertion signals SA-1 to SA-3 to be inserted into the fourth channel and transmitted downstream in the own node.

Each ADM node 101-1 has an optical transmitter 21-1.
However, the ADM node 101-2 has an optical transmitter 21-2a, and the ADM node 101-3 has an optical transmitter 21-3. Each of the ADM nodes 101-1 to 101-3 has its own. From the built-in cross-connects 13-1, 13-2, 13-3
Insert the SA-4 signal and output the fourth channel signal
The optical signal is converted into an optical signal having a wavelength for a channel and output to a self-contained multiplexer 10, which multiplexes the optical signal with the optical signal of another channel directly supplied from the demultiplexer 11 to perform wavelength multiplexing. This is a configuration in which an optical signal is converted into an optical signal and applied to an optical fiber amplifier 12b which is an output amplification stage. Optical fiber amplifier 12b
Then, after optical amplification here, the light is output to the optical fiber transmission line 14, which is a transmission line, and transmitted downstream.

In such a configuration, the optical transmitting terminal 100
Then, the transmission signal of each channel is converted into an optical signal having a wavelength corresponding to the channel by the optical transmitters 1-1 to 1-4 provided for the channel, and is wavelength-multiplexed by the multiplexer 10 to become a wavelength multiplexed optical signal. After being amplified by the optical fiber amplifier 12b, it is sent to the optical fiber transmission line 14.

The optical fiber transmission line 14 includes first to third ADM nodes 101-1 to 101-3 on the way.
When there is information to be received by the M nodes 101-1 to 101-3, the optical transmitting terminal 100 transmits the information using the fourth channel. Further, the first to third ADM nodes 10
If there is information to be transmitted on the downstream side in 1-1 to 101-3, the information is inserted into the fourth channel in the own node and transmitted downstream.

Therefore, the first to third ADM nodes 10
In 1-1 to 101-3, the upstream optical fiber transmission line 14
Multiplexed optical signal received from the optical fiber amplifier 12a
After the optical amplification in step (1), the optical signal of each of the first to third channels is split by a splitter 11, which is a means for splitting each wavelength, to give an optical signal of the first to third channels to a multiplexer 10. The optical signal of the fourth channel is supplied to the optical receivers 20-1, 20-2a, and 20-3 of the own node to be converted into electric signals, and the cross connects 13-1 and 13 of the own node are converted.
-2, 13-3.

In the cross-connects 13-1, 13-2, and 13-3, the fourth signals provided from the corresponding optical receivers 20-1, 20-2a, and 20-3 are provided.
The required signal is branched from the channel signal to produce a branch signal.
The exchange process is performed such as inserting the insertion signals SA-1 to SA-3 which are acquired as SD-1 to SD-3 and inserted into the fourth channel and transmitted downstream in the own node, to the fourth channel.

Then, the cross-connects 13-1, 13-2, 13-3
The signal of the fourth channel exchanged and output from is supplied to the optical transmitters 21-1 to 21-3 of the own node, where it is converted into an optical signal of the wavelength for the fourth channel, Ten
Given to. The multiplexer 10 wavelength-multiplexes the optical signal and the optical signals of the first to third channels, which are demultiplexed for each wavelength from the demultiplexer 11, to obtain a wavelength-division multiplexed optical signal. After optical amplification in 12b, the light is transmitted to the optical fiber transmission line 14 on the downstream side.

In the optical receiving terminal station 102, the wavelength multiplexed optical signal transmitted via the optical fiber transmission line 14 is optically amplified by an optical fiber amplifier 12a which is an amplifier of the optical signal.
The optical receivers 2-1 to 2-1 to 2 are demultiplexed for each wavelength by a demultiplexer 11, which is a means for dividing by wavelength, according to each channel.
Give to 2-4. The optical receivers 2-1 to 2-4 for each channel receive the demultiplexed and input optical signals for the own channel, convert them into electric signals, and output them as received signals SR-1 to SR-4. I do.

Basically, the present system is like this. In each ADM node in the middle of the transmission path, the method of branching all the transmission channels as in the prior art is renewed. Makes it unnecessary to add / drop other channels (A
dd / Drop Multiplexer: ADM)
The purpose is to improve transmission efficiency. And
As a result, the transmission efficiency of the entire channel can be clearly improved as compared with the conventional method.

By the way, in such a system of the present invention, the branch / insert processing (that is, the exchange processing in the middle)
The channel to be selected is a specific channel,
When a certain ADM node needs to increase the transmission capacity, there is a concern that the situation may be such that it cannot be dealt with only by the specific channel. However, in such a case,
The feature of the system of the present invention is that it enables the transmission capacity to be increased without a significant replacement of components including other ADM nodes and transmitting or receiving terminal stations. This will be described as fourth to fourth specific examples.

[First Specific Example] In the system having the basic configuration shown in FIG.
It is assumed that the insertion signal capacity needs to be increased.

The second ADM node 101-2 branches
When it is desired to increase the signal capacity to be inserted, as shown in FIG. 2, in addition to the fourth channel C-4 to which the basic assignment is made, the third channel C-3 is also connected to the second ADM node 10-4.
The constituent elements of the second ADM node 101-2 are changed so as to be assigned as channels for dropping / inserting in 1-2. This change is simply an optical receiver for channel 3 C-3
20-2b is provided on the output side for the third channel C-3 of the duplexer 11, and the output of the optical receiver 20-2b is connected to the cross-connect 13-2.
The optical transmitter 21-2b for the third channel C-3 is provided on the output side of the cross-connect 13-2, and the output of the optical transmitter 21-2b is connected to the multiplexer 10 Channel 3 C-3
Configuration to be given as input for

The cross connect 13-2 in the second ADM node 101-2 includes a third channel C-3 and a fourth channel C-3.
Since the switching operation is performed for a total of two channels C-4, the first specific example of the system of the basic configuration of FIG. ADM node 101-2
After exchanging the branch signal SD-2 and the insertion signal SA-2 in the third ADM node 101-2, the third ADM node 101-3 disposed at a subsequent stage when viewed from the ADM node 101-2 causes the third A to branch.
Regarding the branch signal SD-3 for the DM node 101-3, the fourth channel C- which is a branch channel in the basic configuration is used.
4 and replace the signal originally sent on the third channel C-3 with a signal that performs an exchange operation such as returning to the third channel C-3.

With this configuration, the second ADM
In the node 101-2, the third channel C-3 and the fourth channel C-4, a total of two channels, are branched and the second ADM
After exchanging the branch signal SD-2 and the insertion signal SA-2 at the node 101-2, the third ADM node 101-3 disposed at a subsequent stage when viewed from the ADM node 101-2 branches the signal. The third branch signal SD-3 for the ADM node 101-3 is inserted into the channel C-4.
The signal sent in 3 is returned to channel C-3. Then, the optical signals are converted to optical signals of the wavelengths for the respective channels by the optical transmitters 21-2a and 21-2b, and the optical signals
Sent to. Also, the first and second channels C-1 and C- which remain in the optical signal state even after being demultiplexed by the demultiplexer 11.
The optical signal of No. 2 is also sent from the demultiplexer 11 to the multiplexer 10 as it is, and the multiplexer 10 wavelength-multiplexes the optical signals of the respective channels C-1 to C-4 into a wavelength-multiplexed optical signal. The light passes through an optical fiber amplifier 12b, which is an output amplification stage, and is then amplified downstream and then sent downstream via an optical fiber transmission line 14, which is a transmission line.

In the third ADM node 101-3 on the downstream side,
Here, the branch signal SD-3 for the third ADM node 101-3 to be branched is split by the self-built-in splitter 11 into a signal of the fourth channel from the split channel to obtain an optical receiver 20-3. -3, which is converted into an electric signal, extracted by the self-built-in cross-connect 13-3, and inserted into the fourth channel at the own node and transmitted downstream.
Therefore, there is no need to change the system due to the second ADM node 101-2 further using the third channel to increase the transmission capacity.

As described above, when the transmission capacity needs to be increased in the ADM node in the middle of the transmission path, another channel, for example, the third channel, in addition to the fourth channel, which has been basically allocated, is also assigned to the second channel. Of the second ADM node is changed so as to be allocated as a channel for dropping / inserting in the ADM node of the second ADM node, and the cross-connect in the second ADM node is divided into a third channel and a fourth channel in total of two channels. In order to make the minutes subject to the exchange operation, a configuration is provided in which an exchange operation function for the third channel and the fourth channel is added.

As described above, with respect to the system having the basic configuration shown in FIG. 1, in the first specific example, a total of two channels, the third channel C-3 and the fourth channel C-4, are divided into the second channel C-2 and the fourth channel C-4. After exchanging the branch signal SD-2 and the insertion signal SA-2 in the ADM node 101-2, the ADM node 101-2 branches the signal at the third ADM node 101-3 arranged at a later stage as viewed from the ADM node 101-2. Branch signal for the third ADM node 101-3
The SD-3 is inserted into the fourth channel C-4, which is a branching channel in the basic configuration. The signal originally sent from the third channel C-3 is the third channel.
It can be dealt with simply by setting the specifications to perform the switching operation such as returning to C-3, and it is necessary to increase the transmission capacity without changing the specifications of other stations and nodes including the upstream side and the downstream side at all. In this case, it is possible to cope with an increase in transmission capacity by changing only the node in which the error has occurred, and it is possible to obtain an effect that the system is rich in flexibility and that the system cost associated with the system change can be reduced. Also, since a specific channel is used for branching / insertion at the ADM node in the middle, other channels are used for branching / adding in the middle.
Since it is not used for insertion and time is not devoted to processing therefor, transmission efficiency can be ensured.

As described above, in the first specific example, when it is necessary for each of a plurality of ADM nodes to exchange information with the own node, the channel used for the exchange is set to a specific channel. When it is necessary to increase the transmission capacity of information transfer, another channel is used in addition to the specific channel.

Next, an example in which an ADM node is newly provided on a transmission line will be described as a second specific example. [Second Embodiment] FIG. 3 is a block diagram showing a second embodiment of the first invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. First and second ADM nodes 101-1 and 101- as existing ADM nodes are connected to an optical fiber transmission line 14 connecting the optical transmitting terminal station 100 and the optical receiving terminal station 102.
Assuming that 2 is present, a case will be described in which an ADM node 101-NEW is newly added between the second ADM node 101-2 and the optical receiving terminal station 102.

In the case of the present system, a specific channel, for example, the fourth channel among a plurality of channels is used as a basic setting for information branching / insertion at an intermediate node.
Now, this specific channel is full to cover the transmission capacity used by the already existing ADM node, and the new ADM node is full.
It is assumed that there is no capacity available for the node 101-NEW.

In such a case, the newly installed ADM node 101-NE
In order to add W, the present invention employs a new ADM node 101-3.
The channel used for information branching / insertion in the above is not the fourth channel C-4 but another channel, for example, the third channel C-3. And each existing AD
Of the M nodes 101-1 and 101-2, the first ADM node 101-
1 and the second ADM node 101-2
Converts the element configuration from the configuration in FIG. 1 to the configuration described in FIG.

That is, the cross-connect 13-2 in the second ADM node 101-2, which is an existing ADM node, switches the third channel C-3 and the fourth channel C-4 for a total of two channels. Therefore, for the system having the basic configuration of FIG. 1, as in the first specific example shown in FIG.
An optical receiver 20-2b for the third channel C-3 is provided on the output side for the third channel C-3 of the duplexer 11, and the optical receiver 20-2b is provided.
-2b is connected to the input of the cross-connect 13-2, and the third channel C-3 is connected to the output of the cross-connect 13-2.
, An optical transmitter 21-2b is provided, and the output of the optical transmitter 21-2b is provided as an input for the third channel C-3 of the multiplexer 10.

The cross-connect 13-2 in the second ADM node 101-2 includes a third channel C-3 and a fourth channel C-3.
Since the switching operation is performed for a total of two channels C-4, the first specific example of the system of the basic configuration of FIG. ADM node 101-2
After exchanging the branch signal SD-2 and the insertion signal SA-2 in the above, the new ADM node 101-NEW to be branched by the new ADM node 101-NEW to be arranged at a later stage position as viewed from the ADM node 101-2. The NEW branch signal SD-3 is replaced with a signal that performs an exchange operation such as insertion into the third channel C-3 instead of the fourth channel C-4, which is a branch channel in the basic configuration.

Of course, originally the third channel C-3
Is transmitted using the third channel C-3.
The new ADM node 101-NEW is configured as follows. That is, optical fiber amplifiers 12a and 12b are provided on the input side and output side, respectively, for optical loss compensation, and the wavelength-division multiplexed optical signal transmitted via the optical fiber transmission line 14 receives the input side optical fiber amplifier 12a. The wavelength-division multiplexed optical signal, which is optically amplified by the optical fiber amplifier and input to the demultiplexer 11 and wavelength-division multiplexed by the multiplexer 10, is optically amplified by an optical fiber amplifier 12b provided on the output side and transmitted to a downstream optical fiber Road 14
Output to Input side optical fiber amplifier 12
The wavelength multiplexed optical signal amplified by a is demultiplexed by the demultiplexer 11 for demultiplexing for each wavelength and divided into optical signals for each channel. In this example, the new ADM node 101-a is used. In NEW, instead of channel 4,
The optical signal of the third channel is configured to be received by the optical receiver.

In the new ADM node 101-NEW, the optical receiver 20- for receiving the signal of the third channel branched from the demultiplexed channel and converting it into an electric signal by the self-built duplexer 11 is used. 3 and also has an optical receiver 20
In the ADM node 101-3, an electric signal which is a conversion output of -3 is provided to a self-contained cross-connect 13-3. The cross-connect 13-3 includes a branch signal SD-3 which is a branch signal of the fourth channel provided from the optical receiver 20-3 and an insertion signal SA-3 which is inserted into the third channel and transmitted downstream at the own node. It is for performing the exchange.

The new ADM node 101-NEW has an optical transmitter 21
-3 is provided, and the insertion signal SA-3 is inserted from the self-built-in cross-connect 13-3, and the output signal of the third channel is converted into an optical signal having a wavelength for the third channel, and the self-built-in The signal is output to the multiplexer 10, and the wavelength is multiplexed with the optical signal of the other channel from the demultiplexer 11 by the multiplexer 10 to be converted into a wavelength multiplexed optical signal, which is provided to the optical fiber amplifier 12b which is an output amplification stage. is there.

In such a configuration, the wavelength-division multiplexed optical signal received from the upstream optical fiber transmission line 14 is optically amplified by the optical fiber amplifier 12a and then divided by the demultiplexer 11, which is a means for dividing the wavelength. The optical signals of the first to third channels which are demultiplexed for each wavelength are supplied to the multiplexer 10. Further, in the existing second ADM node 101-2, the optical signal of the fourth channel is given to the optical receiver 20-2a of the own node,
The optical signal of the channel is supplied to the optical receiver 20-2b of the own node, converted into an electric signal, and supplied to the cross-connect 13-2 of the own node.

In the cross-connects 13-1 and 13-2, necessary signals are branched from the signals of the fourth channel given from the corresponding optical receivers 20-1 and 20-2a to form branch signals SD-1 and SD-2. -2, and performs exchange processing such as inserting insertion signals SA-1 and SA-2 to be inserted into the fourth channel and transmitted downstream in the own node to the fourth channel.

Further, in the cross-connect 13-2 in the existing second ADM node 101-2, a necessary signal is branched from the signal of the third channel given from the optical receiver 20-2b to form a branched signal SD-2. The insertion signal SA-2 which is acquired and inserted into the third channel by the own node and transmitted downstream is transmitted to the third channel.
Exchange processing such as insertion into a channel is performed.

In the cross-connect 13-3 of the new ADM node 101-NEW, a necessary signal is branched from the signal of the third channel given from the corresponding optical receiver 20-3 to form a branch signal SD-3. The local node performs an exchange process such as inserting an insertion signal SA-3 to be inserted into the third channel and transmitted downstream at the own node to the third channel.

Then, the cross-connects 13-1, 13-2, 13-3
The signal of the fourth channel exchanged and output from is supplied to the optical transmitters 21-1 to 21-3 of the own node, where the signal of the fourth channel is an optical signal of the wavelength for the fourth channel. Further, the signal of the third channel is converted into an optical signal of a wavelength for the third channel, and is provided to the multiplexer 10. The multiplexer 10 wavelength-multiplexes this optical signal and the optical signal of each channel provided by demultiplexing for each wavelength from the demultiplexer 11 to make a wavelength-division multiplexed optical signal, which is optically amplified by an optical fiber amplifier 12b. Thereafter, the light is transmitted to the optical fiber transmission line 14 on the downstream side.

As described above, the specific channel is set to the ADM on the way.
In the method used for dropping and inserting signals at nodes,
When it is desired to add a new ADM node in a case where the transmission capacity used by the existing ADM node is full, the existing ADM node upstream of the new ADM node 101-NEW may use the optical transmission terminal 100 or The new ADM node 101-1 is configured to perform a switching operation of inserting a signal transmitted from the existing ADM node 101-1 on the fourth channel C-4 and branched by the new ADM node 101-NEW into the third channel C-3. The transmission channel used by the node is another channel having sufficient capacity. Therefore, the ADM node can be newly installed while maintaining the transmission efficiency of the system and compensating for the lack of capacity without changing the configuration of the existing system.

Such a concept can be further modified as follows. [Third Specific Example] That is, the concept as in the second specific example can be modified as follows. That is,
Branching a signal at an ADM node on a specific channel
In the method used for insertion, while preventing the transmission capacity used by the existing ADM node from becoming full,
The new ADM node has a flexible system configuration that can be established without affecting the configuration of the existing system at all.

The basic configuration is, for example, a configuration excluding the configuration of the new ADM node 101-NEW in FIG. 3 from FIG.
Therefore, the second ADM node 101-2 is the third ADM node from the beginning.
And the signal of the fourth channel is branched and taken in,
The information to be sent to the downstream side is inserted into the third channel for the third channel, and inserted into the fourth channel for the fourth channel, and the information is sent to the downstream of the signals of the third or fourth channel. What is necessary for the newly installed ADM node is to exchange the channel corresponding to the channel used in the new ADM node and transmit the data, and the cross-connect 13-2 is provided with an exchange function for that.

In this way, when a new ADM node is to be added, the newly established ADM node 101-NEW has a margin in transmission capacity among a plurality of specific channels assigned to use for information transfer. In order to use a channel having a channel, a channel-selected configuration is prepared, and a third channel C-3 and a fourth channel are provided in the cross-connect 13-2 of the existing second ADM node 101-2. The new ADM node 101-NEW on the downstream side can be provided with a branch signal while the switching operation is performed on a total of two channels of C-4.
The function of exchanging the signal for the node so that it is inserted into the assigned channel used by the new ADM node is set in the cross-connect 13-2.

The upstream optical transmitting terminal 100 or the existing ADM
A signal transmitted from the node on the third and fourth channels C-3 and C-4, which needs to be branched by the new ADM node, is transmitted to the existing ADM node, which is upstream of the new ADM node, by the new ADM node. In this configuration, a new ADM node can be added without changing the configuration of the existing system, and there is no shortage of transmission capacity. be able to. Also, since a specific channel is used for dropping / inserting at the ADM node in the middle, other channels are not used for dropping / inserting in the middle, and time is spent for processing for that. Therefore, transmission efficiency can be ensured.

As described above, in the third specific example, when it is desired to add a new ADM node, the existing ADM node 101-2 transmits the third signal from the optical transmitting terminal 100 or the existing ADM node 101-1 to the third terminal.
The signal transmitted from the new ADM node 101-3 transmitted through the fourth channels C-3 and C-4 is inserted into the third channel C-3 to add a new ADM node 10-3.
If 1-NEW has a function of dropping / inserting only the third channel C-3, there is flexibility that there is no subsystem that needs to be added or rearranged to other existing ADM nodes 101-1 and 101-2. A low-cost system can be constructed.

Next, a fourth specific example of a technique for improving the transmission efficiency by minimizing the amount of transmission in the channel branched by the ADM node will be described. [Fourth specific example] Basically, when each of a plurality of ADM nodes needs to exchange information with its own node and another, a plurality of specific channels are used for the exchange. The remaining channels are allowed to pass through the ADM node without branching, thereby improving the transmission efficiency of the entire system. The information that is not required in the above is collected into channels that are not used on the downstream side among a plurality of specific channels, and the processing of dropping / inserting is reduced to improve the transmission efficiency.

FIG. 4 is a block diagram showing a fourth specific example. 1 to 3 are denoted by the same reference numerals, and description thereof will be omitted. FIG. 4 shows the upstream ADM node 101-.
L and the downstream ADM node 101-L + 1
The upstream ADM node 101-L is a duplexer.
Of the 11 split optical signals of each channel,
Optical receiver 20-La for C-4 and optical receiver for channel C-3
Receives and captures at 20-Lb, thereby
A signal SD-L that branches C-3 and C-4 and branches them at the cross-connect 13-L included in the ADM node 101-L.
The signal SA-L to be inserted is exchanged, and the signal of each channel is converted into an optical signal by the optical transmitter 21-La for channel C-4 and the optical transmitter 21-Lb for channel C-3. The multiplexer 10 wavelength-multiplexes the optical signal of each of the channels C-3 and C-4 and the optical signal of each of the channels C-1 and C-2 which have not been subjected to branching, and wavelength-multiplexes the optical signal. The optical fiber amplifier 12b, which is an output amplifying stage, is then optically amplified, and then sent downstream via an optical fiber transmission line 14, which is a transmission line.

The ADM node 101-L + 1 disposed behind the ADM node 101-L is adapted to split the optical signal of the channel C-4, and the ADM node 101-L + 1 is provided with a branching filter. Of the 11 optical signals of each channel, the optical signal is received and received by the optical receiver 20-L + 1 for channel C-4, whereby the channel C-4 is branched.
The cross-connect 13-L + 1 included in the M node 101-L + 1 exchanges the signal SD-L + 1 branched and the signal SA-L + 1 to be inserted into the cross-connect 13-L + 1, and outputs an optical transmitter 21 for the channel C-4. The optical signal of -L + 1 is converted into an optical signal, and the optical signal of the channel C-3 is combined with the optical signals of the channels C-1,.
The optical signal of (3) is wavelength-multiplexed and converted into a wavelength-multiplexed optical signal, and then passes through an optical amplifier 12b, which is an output amplification stage. send.

As described above, in this specific example, the downstream ADM node 101-L is located downstream of the downstream ADM node 101-L.
In 101-L + 1, signals that do not need to be split
In the node 101-L, transmission is performed on the channel C-3 which is not branched by the downstream ADM node 101-L + 1.

For this reason, in the downstream ADM node 101-L + 1, the redundant signal included in the branched channel C-4 is reduced, and the band of the signal dropped / added in the channel C-4 and the ADM node 101-L is reduced. Can be used effectively.

[Fifth Specific Example] FIG. 5 is a block diagram showing a fifth specific example. The same parts as those in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof will be omitted. This example is based on an ADM node group of the upstream group and an ADM node group of the downstream group.
The transmission efficiency is improved by grouping the data into a group of nodes and making the branching channel different in each group.

In this example, in the optical transmitting terminal 100, the signals SD-1 to SD-L branched by the ADM nodes 101-1 to 101-L in the upstream group are transmitted on the channel C-4, and the signals are transmitted to the downstream group. SD-L branched at ADM nodes 101-L to 101-M
~ SD-M is transmitted on channel C-3. It is assumed that this is realized by providing control means for that.

Further, the ADM node 101-
1 to 101-L-1 and the ADM node 101-L + in the downstream group
1 to 101-M drop and insert only the channel C-4 defined as a channel to be used for dropping and inserting in the basic configuration, and the ADM node 101-L at the boundary between the two groups is the channel C-4 and the channel C-3. Is branched.

The cross-connect 13-L at the ADM node 101-L at the boundary includes the signal SD-L branched from the channel C-4 and the channel C-3 at the own node, and the signal SA- L is exchanged.
Signals that do not branch are transmitted on channel C-3, and signals that branch on ADM nodes 101-L to 101-M in the downstream group are transmitted on channel C-4.

As described above, the optical transmitting terminal 100 and the boundary AD
In the M node 101-L, switching control is performed so that a signal that is not dropped or inserted in each of the other ADM nodes is not inserted into a channel that is dropped or inserted in each of the ADM nodes. It can be used effectively.

In particular, ADMs other than the boundary ADM node 101-L
In the node, only the channel C-4 specified as the channel used for dropping / inserting in the basic configuration is dropped /
Since the channel is inserted and the other channels are not branched, the boundary AD
All the ADM nodes other than the M node 101-L may have the same configuration, thus reducing the system cost.
In addition, since a channel other than the channel C-4, in this example, the channel C-3 can be used for transmitting information to be branched by the ADM node, it is possible to flexibly cope with a shortage of transmission capacity. Become.

Next, an example capable of coping with a case where the capacity of a signal to be inserted / branched at each ADM node has been increased will be described as a sixth specific example. [Sixth Specific Example] FIG. 6 is a configuration diagram showing a sixth specific example. The specific example shown in FIG. 6 can cope with the case where the capacity of a signal to be inserted / branched at each of the ADM nodes 101-1 to 101-M is increased in the fifth specific example shown in FIG. It is shown.

The same parts as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. In this system, the channel
In addition to C-3 and C-4, channel C-2 is used for drop / insert. The ADM 101-L at the boundary drops and inserts the channel C-3 and the channel C-4, but one of the ADM nodes 101-L + 1 to 101-M in the downstream group, the ADM 101-L.
The node 101-K is configured to be able to add / drop not only the channel C-4 but also the channel C-2.

An ADM node is connected to an optical fiber transmission line 14 connecting the optical transmitting terminal station 100 and the optical receiving terminal station 102 with 101-1 to 101-1.
101-L, ~ 101-K, ~ 101-M are provided in order, and among them, ADMs of 101-1 to 101-L-1 will be described below.
The node is an upstream group, and 101-L is a boundary ADM node, and 101-L to 101-L including this boundary ADM node 101-L.
ADM nodes up to 01-K are intermediate groups, 101-K + 1 to 1
The ADM nodes up to 01-M are called the downstream group.

In this example, the optical transmission terminal station 100 has a total of four communication channels of channels C-1 to C-4, and these channels C-1 to C-4 have different wavelengths for each channel. The use of the optical signal is not different from the previous specific example. Further, the optical transmitting terminal station 100 transmits the signals SD-1 to SD-L branched from the ADM nodes 101-1 to 101-L-1 belonging to the upstream group on channel C-4, and outputs the signals to the boundary ADM node 101-L. Signals SD-L to SD-K branched at ADM nodes 101-L to 101-K in the intermediate group including L are transmitted on channel C-3, and ADM nodes 101-K +
Signals SD-K to SD-M branched from 1 to 101-M are channel C-2
Is transmitted. It is assumed that control means for this is provided to realize this.

In this system, the boundary ADM node 10
In the 1-L cross-connect 13-L, the signals SD-L + 1 to SD-K transmitted by the channel C-3 and branched by the ADM nodes 101-L to 101-K and the ADM nodes 101-1 to 101-L Out of the signals SA-1 to SA-L inserted by the ADM nodes 101-L + 1 to
Signals SD-L + 1 to SD-K branched at 101-K are transmitted on channel C-4, and among insertion signals SA-1 to SA-L,
The signal to be transmitted to the optical receiving terminal 1-2 is configured to be transmitted on the channel C-3.

Further, in the ADM node 101-K belonging to the intermediate group, the cross-connect 13-K transmits the ADM node 101-K + 1 to ADM node 101-K + 1 to 10 transmitted on the channel C-2.
Signals SD-K + 1 to SD-M branched to 1-M and ADM node 101
Of the signals SA-L to SA-K inserted at -L to 101-K, AD
Signals SD-K + 1 to SD-M branched at M nodes 101-K + 1 to 101-M
Is transmitted on channel C-4, and the signal transmitted to the optical receiving terminal 102 is exchanged so as to be transmitted on channel C-2.

In the present system having such a configuration, the optical transmitting terminal station 100 transmits four channels C-1 to C-4 in this example.
The communication channel of the system is converted into an optical signal, which is multiplexed into a wavelength multiplexed optical signal, and transmitted downstream.

At this time, the optical transmitting terminal station 100 transmits the signals SD-1 to SD-L branched from the ADM nodes 101-1 to 101-L-1 belonging to the upstream group on the channel C-4. Of the intermediate group including the boundary ADM node 101-L
The signals SD-L to SD-K branched at the DM nodes 101-L to 101-K are transmitted on the channel C-3, and A of the downstream group is transmitted.
Signals SD-K to SD-M branched at DM nodes 101-K + 1 to 101-M
Is transmitted on channel C-2.

As a result, the AD belonging to the upstream group
Since the signals branched at the M nodes 101-1 to 101-L-1 are transmitted on the channel C-4, the ADM nodes 101-1 to 101-L- are configured to demultiplex the channel C-4.
In 1, the signal to be branched at the own node is
The cross-connects 13-1 and 13-L-1 perform a switching operation of branching and inserting a signal to be inserted into the channel C-4, and the optical transmitters 21-1 to 21-L-1 The signal is converted into an optical signal of the wavelength for the channel and output to the self-contained multiplexer 10, which performs wavelength division multiplexing with an optical signal of another channel directly supplied from the demultiplexer 11, and performs wavelength division multiplexing. The signal is converted into an optical signal and transmitted downstream via an optical fiber amplifier 12b which is an output amplification stage.

The downstream AD closest to the ADM node 101-L-1
The M node is the boundary ADM node 101-L. Boundary AD
In the M node 101-L, the channels C-3 and C-4 of the channels demultiplexed by the demultiplexer 11 are transmitted to the optical receiver 20-L.
a to 20-Lb as an electric signal to be received, and own cross-connect 13-L is connected to channel C-4 and channel C-3.
, The signal SD-L branched at the own node and the signal SA-L inserted at the own node are exchanged.
Signals that do not branch to 2 are transmitted on channel C-3, and signals that branch on the ADM nodes 101-L + 1 to 101-M in the intermediate and downstream groups are transmitted on channel C-4.

The channels C-4 and C-3 are converted into optical signals of the wavelengths for the corresponding channels by the optical transmitters 21-La and 21-Lb, and output to the self-contained multiplexer 10. The multiplexer 10 wavelength-multiplexes the optical signal with the optical signal of another channel directly supplied from the demultiplexer 11 into a wavelength-division multiplexed optical signal, and transmits the optical signal downstream through an optical fiber amplifier 12b which is an output amplification stage.

Thus, to the ADM nodes of the intermediate group and the downstream group, only the signals that need to be branched by the ADM nodes are transmitted by the channel C-4, and are unnecessary for the ADM nodes of the intermediate group and the downstream group. The necessary information is exchanged with the optical receiving terminal 102 so as to be concentrated on the channel C-3, and passes through the ADM nodes of the intermediate group and the downstream group.

The ADM node 101- belonging to the intermediate group
ADM node 101-K-1 belonging to the intermediate group from L + 1
In, the cross-connects 13-L + 1 to 13-K-1 separate the signal transmitted on the channel C-4, insert a signal to be inserted at the own node, and transmit the channel C-4 to the downstream side. Using the exchange to send works. Therefore, a branch in this section is determined for channel C-4.

In the ADM node 101-K, the cross-connect 13-K is the A-node transmitted on the channel C-2.
Signal SD-K + 1 branched to DM nodes 101-K + 1 to 101-M
~ Signal inserted at SD-M and ADM nodes 101-L ~ 101-K
Of SA-L to SA-K, signals SD-K + 1 to SD-M branched at ADM nodes 101-K + 1 to 101-M are transmitted on channel C-4 and transmitted to optical receiving terminal 102. The signal to be transmitted on channel C-2.

Thus, the AD belonging to the downstream group
In the M nodes 101-K + 1 to 101-M, since the branched signal is transmitted on channel C-4,
ADM node 101-K + 1 configured to split C-4
101-M, the cross-connects 13-K + 1 to 13-M perform the switching operation of dropping the signal to be dropped at the own node and inserting the signal to be inserted into the channel C-4. The optical transmitters 21-K + 1 to 21-M convert the signals into optical signals of the wavelengths for the corresponding channels and output the optical signals to the self-contained multiplexer 10, and the multiplexer 10 Wavelength multiplexing is performed with an optical signal of another channel directly supplied from 11 to make a wavelength multiplexed optical signal, and transmitted downstream via an optical fiber amplifier 12b which is an output amplification stage.

As described above, even when the capacity of a signal to be dropped / inserted at each ADM node is large, the ADM node
A plurality of specific ADM nodes having a function of exchanging signals between channels so that signals can be dropped / inserted for a plurality of channels such as 101-L and 101-K, and arranged on a transmission line as appropriate. By doing so, it is possible to effectively use the channels and the bands of all ADM nodes.

In particular, such a specific ADM node 101-L,
By using 101-K in part, in other ADM nodes, only channel C-4, which is defined as a channel used for dropping / inserting in the basic configuration, is dropped / inserted, and other channels are not dropped. Therefore, all ADM nodes other than the specific ADM nodes 101-L and 101-K may have the same configuration, so that the system cost can be reduced. In the example, since the channels C-3 and C-2 can be used for transmitting information to be branched by the ADM node, it is possible to flexibly cope with a shortage of transmission capacity.

Further, since addition and rearrangement of channel routes are not required, a system can be configured at low cost while maintaining expandability, and maintenance can be facilitated. It should be noted that the present invention is not limited to the specific examples described above, and can be implemented with various modifications.

[0096]

As described above, the wavelength division multiplexing optical transmission system according to the present invention comprises an optical transmitting terminal, an optical receiving terminal and an A
DM nodes and other subsystems are thimble and small-scale, and can be easily operated and managed. In addition, they enable highly reliable wavelength-division multiplexed optical transmission.
Addition of M nodes and expansion of transmission capacity between ADM nodes or over the entire transmission path do not require complicated rearrangement of channel paths, but can be flexibly handled only by adding small subsystems. In addition, high flexibility can be obtained, for example, by effectively using the bandwidth of the ADM node and realizing a lightwave network suitable for the future multimedia information society.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the present invention, and is a configuration diagram of a wavelength division multiplexing optical transmission system as a first specific example to which a basic concept of the present invention is applied.

FIG. 2 is a diagram for explaining the present invention, and is a configuration diagram of a wavelength division multiplexing optical transmission system as a second specific example of the present invention.

FIG. 3 is a diagram for explaining the present invention, and is a configuration diagram of a wavelength division multiplexing optical transmission system as a third specific example of the present invention.

FIG. 4 is a diagram for explaining the present invention, and is a configuration diagram of a wavelength division multiplexing optical transmission system as a fourth specific example of the present invention.

FIG. 5 is a diagram for explaining the present invention, and is a configuration diagram of a wavelength division multiplexing optical transmission system as a fifth specific example of the present invention.

FIG. 6 is a diagram for explaining the present invention, and is a configuration diagram of a wavelength division multiplexing optical transmission system as a sixth specific example of the present invention.

FIG. 7 is a diagram illustrating a configuration example of a wavelength multiplexing optical transmission system that has been conventionally considered.

[Explanation of symbols]

1-1, 1-2, 1-3, 1-4 ... optical transmitters 2-1, 2-2, 2-3, 2-4 ... optical receivers 10 ... multiplexers 11 ... duplexers 12 ... Optical fiber amplifiers 13-1, 13-2, ~ 13-L, ~ 13-K, ~ 13-M ... cross-connect 14 ... optical fiber for transmission 15 ... optical fiber amplifiers for optical repeaters 20-1, 20-2a, 20-2b, ~ 20-L, ~ 20-K, ~ 20-M ... Branch signal light receiver 21-1, 21-2a, 21-2b, ~ 21-L, ~ 21-K, ~ 21-M ... Additional signal light transmitters 30-1, 30-2, ~ 30-8 ... Channel 100 ... Optical transmission terminal stations 101-1, 101-2, ~ 101-L, ~ 101-K, ~ 101-M ... AD
M node 102: optical receiving terminal 103: conventional ADM node S-1, S-2, S-3, S-4: transmission signals SD-1, SD-2, ~ SD-L, ~ SD-K, ~ SD-M ... branch signal SA-1, SA-2, ~ SA-L, ~ SA-K, ~ SA-M ... insertion signal SR-1, SR-2, ~ SR-L, ~ SR-K, ~ SR-M: Received signal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication H04J 1/10

Claims (3)

[Claims] An optical transmission using light of different wavelengths for each channel, wherein a plurality of channels are optically multiplexed and transmitted through a transmission path, and the transmission path is wavelength-multiplexed on the transmission path. A plurality of ADM nodes having a function of dropping / adding one channel from a plurality of channels transmitted (Add / Drop Multiplexer: ADM) are provided, and a specific channel among the channels is dropped at each ADM node. In the transmission system, the ADM node that needs to increase the transmission capacity among the ADM nodes is assigned another channel other than the specific channel to the ADM node. , And the signal is added to the other channel and returned to the transmission path.
A wavelength division multiplexing optical transmission system comprising means for adding a signal to be passed to an M node to the specific channel and returning the signal to a transmission path. 2. An optical transmitting terminal for transmitting a wavelength-division multiplexed optical signal, an optical receiving terminal for receiving a wavelength-division multiplexed optical signal, and a transmission line connecting the optical transmitting terminal and the optical receiving terminal. ,
One channel is dropped / added from a plurality of wavelength-multiplexed channels transmitted through this transmission line (Add / Drop Multip
lexer: ADM) and one or more second ADM nodes for dropping / inserting two or more channels, respectively.
A cross-connect having a function of exchanging signals between channels to be inserted; and a signal branched at the second ADM node to at least one of the optical transmitting terminal and the first ADM node. Is sent on a specific channel and the second A
A wavelength division multiplexing optical transmission system comprising means for transmitting a signal that does not branch at a DM node through another channel if necessary. 3. An optical transmitting terminal for transmitting a wavelength-division multiplexed optical signal, an optical receiving terminal for receiving a wavelength-division multiplexed optical signal, and a transmission line connecting the optical transmitting terminal and the optical receiving terminal. ,
A specific channel is dropped / added from a plurality of wavelength-multiplexed channels transmitted through this transmission path (Add / Drop
ltiplexer: ADM), the first ADM node having a function of dropping / inserting the specific channel and one or more second channels other than the specific channel. A second A located between
A DM node, wherein in the optical transmitting terminal and the second ADM node,
Means are provided for controlling transmission of a signal branched at the first ADM node on the first channel and transmission of a signal not branched at the first ADM node on the second channel. The wavelength division multiplexing optical transmission system according to claim 2.