JP5178544B2 - WDM transmission system - Google Patents

Description

  The present invention relates to a wavelength division multiplexing transmission system including a wavelength extension system.

In a wavelength division multiplexing transmission system, it has become possible to increase the number of wavelengths to be inserted into a certain wavelength band by increasing the number of wavelengths inserted in a certain wavelength band and improving transmission / reception unit characteristics and error correction capability. Yes. When removing an existing wavelength and adding a new wavelength, it is necessary to stop the existing wavelength multiplexing transmission system until the wavelength addition / adjustment is completed, but the existing wavelength multiplexing transmission system is already in service. Therefore, it may be difficult to stop the entire existing wavelength and increase the wavelength.

Based on this background, the existing wavelength was manually removed in-service and the level was adjusted by inserting a new additional wavelength, but the wrong wavelength was inserted due to human error or was newly installed. There is a risk that the wavelength level is adjusted excessively high, and the existing wavelength level is relatively lowered, thereby affecting the in-service existing line. Moreover, since it implements manually, the subject that adjustment time became long occurred.

As a method of automatically controlling the optical output level of the additional wavelength in a short time while avoiding such quality degradation of the existing wavelength, a prior art as in Patent Document 1 below has been proposed. According to the following Patent Document 1, by controlling the optical output level of the additional wavelength so that the optical output level of the existing wavelength does not fall below the minimum allowable optical output level, the line quality of the existing wavelength is maintained within an allowable range. It becomes possible to automatically adjust the optical output level of the additional wavelength.

JP 2005-269007 A

  Since the conventional wavelength multiplex transmission system is configured as described above, in Patent Document 1 described above, the insertion of the additional wavelength and the optical output level in the case of controlling the optical output level of the additional wavelength while maintaining the number of existing wavelengths. Although it describes the control method, it does not describe how to insert the additional wavelength and control the optical output level when removing some of the existing wavelengths and increasing the number of additional wavelengths in the corresponding wavelength band. Absent.

Further, in Patent Document 1, the optical output level of the existing wavelength can be lowered up to the minimum allowable optical output level. If the minimum allowable optical output level is misidentified, the existing line quality may be affected. There was a problem.

  The present invention has been made to solve the above-described problems. When a part of the existing wavelengths is removed and the number of additional wavelengths in the corresponding wavelength band is increased, the additional wavelength is inserted and the optical signal is added. By automatically controlling the output level, it is possible to increase the number of wavelengths in a shorter time by suppressing the effects of wavelength insertion mistakes and manual adjustments of the optical output level caused by manual adjustments as in the past. An object of the present invention is to obtain a wavelength division multiplexing transmission system.

  The wavelength division multiplexing transmission system according to the present invention is more than the number of existing wavelengths removed in the wavelength band corresponding to the removed existing wavelengths when some of the existing wavelengths in the existing wavelength division multiplexing system are removed. In a wavelength division multiplexing transmission system equipped with a wavelength expansion system for increasing wavelengths by increasing the number of wavelengths, the wavelength expansion system outputs optical transmission signals of different wavelengths set at a wavelength interval narrower than the existing wavelength in the existing wavelength division multiplexing transmission system. Optical transmission means for a plurality of additional wavelengths, first optical multiplexing means for multiplexing optical transmission signals output from the plurality of optical transmission means, and first optical multiplexing to the wavelength multiplexed signal in the existing wavelength multiplexing transmission system A second optical multiplexing means for multiplexing the optical transmission signals combined by the means; an optical amplifying means for amplifying the wavelength multiplexed signal combined by the second optical multiplexing means; First optical branching means for branching a part of the wavelength multiplexed signal output from the width means, wavelength level monitoring means for measuring each wavelength level in the wavelength multiplexed signal branched by the first optical branching means, The existing wavelength and wavelength band removed in the existing wavelength multiplexing transmission system are specified based on each wavelength level in the wavelength multiplexed signal measured by the wavelength level monitoring means, and included in the specified wavelength band of the optical transmission means The optical transmission means having the additional wavelength to be specified is specified, the target value of the wavelength level measured by the wavelength level monitoring means corresponding to each specified optical transmission means is set uniformly, and measured by the wavelength level monitoring means An extension format that controls the optical output level of the optical transmission signal that is output from the optical transmission means that is specified so that the target wavelength level is the target value. / Is obtained by a transmission level control means.

According to this invention, when a part of the existing wavelengths is removed and the number of existing wavelengths removed is increased to a wavelength band corresponding to the removed existing wavelengths, the number of existing wavelengths removed is increased. Specification of wavelength and wavelength band, specification of optical transmission means having an additional wavelength included in the specified wavelength band, setting of target value of wavelength level measured by wavelength level monitoring means corresponding to each specified optical transmission means, And automatic detection, calculation, and control comprising control of the optical output level of the optical transmission signal output from the optical transmission means specified so that the wavelength level measured by the wavelength level monitoring means becomes the target value. Therefore, it is possible to suppress an influence on an existing wavelength due to an error in wavelength insertion caused by manual operation or an error in adjustment of an optical output level as in the past. Moreover, since it controls automatically, it can extend in a short time rather than implementing manually. Further, since no control is performed only by removing the existing wavelength, there is an effect that the wavelength can be added to the existing wavelength multiplexing transmission system with almost no restrictions.

It is a block diagram which shows the structure of the wavelength division multiplexing transmission system provided with the wavelength extension system by Embodiment 1 of this invention. It is a block diagram which shows the structure of the existing wavelength division multiplexing transmission system. It is a flowchart which shows the wavelength extension procedure by Embodiment 1 of this invention. It is explanatory drawing which shows the wavelength extension method divided for every case by Embodiment 1 of this invention. It is a block diagram which shows the structure of the wavelength division multiplexing transmission system provided with the wavelength extension system by Embodiment 2 of this invention. It is a flowchart which shows the wavelength extension procedure by Embodiment 2 of this invention.

An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a wavelength division multiplexing transmission system provided with a wavelength extension system according to Embodiment 1 of the present invention, and FIG. 2 is a block diagram showing a configuration of an existing wavelength division multiplexing transmission system.

  In FIG. 2 showing an existing wavelength division multiplexing transmission system, an existing wavelength multiplexing apparatus transmitter (existing WDM apparatus TX) 1 is provided on the transmission side, and wavelength division multiplexed signals obtained by multiplexing optical transmission signals of different wavelengths are used as transmission lines. Output. The optical repeater 2 is provided between the transmission side and the reception side, and includes a plurality of optical amplifiers and the like, and optically amplifies the wavelength multiplexed signal. The existing wavelength multiplexing device receiver (existing WDM device RX) 3 is provided on the receiving side, and demultiplexes the wavelength multiplexed signal received from the transmission path and inputs optical transmission signals of different wavelengths.

  In FIG. 1 showing a wavelength division multiplexing transmission system having a wavelength extension system in the existing wavelength division multiplexing transmission system, the wavelength extension system is removed when a part of the existing wavelengths in the existing wavelength division multiplexing transmission system is removed. It is intended to increase the number of wavelengths in the wavelength band corresponding to the wavelength by increasing the number of existing wavelengths removed.

On the transmission side, the additional wavelength optical transmission units (optical transmission units) 51 to 5n output optical transmission signals having different wavelengths set in advance. Since the optical transmission units 51 to 5n are required to have a transmission quality higher than that of the existing wavelength optical transmission unit, the optical transmission units 51 to 5n have performance capable of transmission even at a wavelength interval narrower than the existing wavelength. Specifically, the required performance is determined by the transmission path to be applied and the line quality. The optical multiplexing unit (first optical multiplexing unit) 6 combines optical transmission signals output from the optical transmission units 51 to 5n. The optical multiplexing unit 6 includes not only a function of optical multiplexing but also a chromatic dispersion compensating fiber and an optical amplifier according to the conditions of the transmission path, so that the optical output levels of the additional wavelengths that are optically multiplexed are aligned to some extent. It is composed of.

The optical coupler (second optical multiplexing means) 7 multiplexes the optical transmission signal combined by the optical multiplexing unit 6 with the wavelength multiplexed signal output from the existing wavelength multiplexing device transmission unit 1. The optical amplifier (optical amplification means) 8 amplifies the wavelength multiplexed signal combined by the optical coupler 7. The optical coupler (first optical branching means) 9 branches a part of the wavelength multiplexed signal output from the optical amplifier 8. The wavelength level monitor unit (wavelength level monitor means) 10 measures each wavelength level in the wavelength multiplexed signal branched by the optical coupler 9. For example, an optical spectrum analyzer or the like is applied to the wavelength level monitor unit 10 and has a function of detecting an optical output level corresponding to each different wavelength output from the optical transmitters 51 to 5n with sufficient resolution. It is.

On the receiving side, the optical coupler (second optical branching means) 11 branches the optical reception signal of the additional wavelength among the wavelength multiplexed signals. The optical demultiplexing unit (optical demultiplexing means) 12 demultiplexes the optical reception signal branched by the optical coupler 11 into different wavelengths. The optical demultiplexing unit 12 includes not only a function of optical demultiplexing but also a chromatic dispersion compensating fiber and an optical amplifier according to the conditions of the transmission path, and the optical reception level of the additional wavelength that has been demultiplexed is It is configured to be aligned to some extent. The optical receiving units (optical receiving units) 131 to 13n for the additional wavelengths are used to input optical reception signals having different wavelengths that are demultiplexed by the optical demultiplexing unit 12. The optical receivers 131 to 13n are required to have an error correction capability equal to or higher than that of the optical receivers having the existing wavelengths, and thus have a performance capable of transmitting even at a wavelength interval narrower than the existing wavelengths. Specifically, the required performance is determined by the transmission path to be applied and the line quality.

On the transmission side, the extension determination / transmission level control unit (addition determination / transmission level control means) 15 is configured to remove the existing wavelength and the removed existing wavelength based on each wavelength level in the wavelength multiplexed signal measured by the wavelength level monitor unit 10. While specifying a wavelength band, a plurality of optical transmitters having additional wavelengths included in the specified wavelength band are specified from among the optical transmitters 51 to 5n, and wavelength levels corresponding to the specified plurality of optical transmitters, respectively. Optical transmission output from the optical transmission unit that is set so that the target value of the wavelength level measured by the monitor unit 10 is uniform and the wavelength level measured by the wavelength level monitor unit 10 becomes the target value. The optical output level of the signal is controlled. Since the wavelengths of the optical transmission signals output from the optical transmission units 51 to 5n are set in advance, the extension determination / transmission level control unit 15 performs optical transmission output from the optical transmission units 51 to 5n. Each wavelength of the signal is recognized in advance.

Next, the operation will be described.
As shown in FIG. 2, in the existing wavelength division multiplexing transmission system before expansion, the wavelength multiplexed signal output from the existing wavelength multiplexing apparatus transmitter 1 to the transmission path is transmitted while being optically amplified by the optical repeater 2. The signal is received by the wavelength multiplexing device receiver 3.

In the existing wavelength division multiplexing transmission system shown in FIG. 2, when a part of the existing wavelengths is removed and the number of wavelengths is increased to a wavelength band corresponding to the removed existing wavelengths by increasing the number of removed existing wavelengths. As shown in FIG. 1, the wavelength extension system provided in the existing wavelength division multiplexing transmission system is applied.

In FIG. 1, the optical transmission signal of the additional wavelength output from the optical transmitters 51 to 5n of the additional wavelength is optically combined by the optical multiplexer 6, and the optically combined additional wavelength and the existing wavelength multiplexed signal are optically combined by the optical coupler 7. The insertion loss is compensated by the optical amplifier 8. The optical output of the optical amplifier 8 is a wavelength multiplexed signal in which the existing wavelength and the additional wavelength are optically multiplexed, and is optically branched by the optical coupler 9, and the wavelength level monitor unit 10 has each wavelength level in the optically multiplexed wavelength multiplexed signal. Measure. Information on the optical output level for each wavelength measured by the wavelength level monitor unit 10 is output to the extension determination / transmission level control unit 15 and the optical output levels of the optical transmitters 51 to 5n of the additional wavelength are determined according to the procedure described later. Control.

On the other hand, the wavelength multiplexed signal obtained by optically combining the existing wavelength multiplexed signal and the additional wavelength is transmitted while being optically amplified by the optical repeater 2 through the transmission path, and the existing wavelength multiplexing device receiver 3 and the additional wavelength light are transmitted by the optical coupler 11. The light is branched to the demultiplexing unit 12. The existing wavelength is received by the existing wavelength multiplexing device receiver 3. The additional wavelength is optically demultiplexed into wavelengths by the optical demultiplexing unit 12 and received by the optical receiving units 131 to 13n for each additional wavelength.

Next, the procedure for increasing the wavelength will be described.
FIG. 3 is a flowchart showing a wavelength extension procedure according to the first embodiment of the present invention, and FIG. 4 is an explanatory diagram showing a wavelength extension method divided for each case according to the first embodiment of the present invention. Hereinafter, a description will be given with reference to FIGS. 1, 3, and 4.

The optical transmission units 51 to 5n of the additional wavelengths are in an off state before the expansion. A part of the existing wavelength is removed in the existing wavelength multiplexing device transmitter 1. For the wavelength to be removed, it is necessary to move the traffic to another wavelength or line in advance.

When the existing wavelength is removed, the optical output level of the removed wavelength is greatly reduced in the wavelength level monitor unit 10, so that the extension determination / transmission level control unit 15 can detect that the existing wavelength has been removed. (FIG. 3: ST1, ST2). The extension determination / transmission level control unit 15 identifies the wavelength band removed from the removed existing wavelength (FIG. 3: ST3), and identifies the added wavelength included in the removed wavelength band. For example, the extension determination / transmission level control unit 15 stores in advance a wavelength table composed of wavelength bands corresponding to the respective existing wavelengths, and obtains the wavelength band corresponding to the removed existing wavelengths based on the wavelength table. In addition, since the extension determination / transmission level control unit 15 recognizes in advance each wavelength of the optical transmission signal output from the optical transmission units 51 to 5n, the additional wavelength included in the removed wavelength band is determined. This can be determined from among the optical transmitters 51 to 5n.

Here, as shown in FIG. 4A, when one wavelength is removed, the added wavelength included in the wavelength band corresponding to the removed existing wavelength is one wavelength (case 1). In this case, this is not included in the first embodiment. On the other hand, when one existing wavelength is removed and the number of added wavelengths included in the wavelength band corresponding to the removed existing wavelength is two wavelengths (case 2), one wavelength is added. In this case, the extension determination / transmission level control unit 15 proceeds to ST6 shown in FIG. 3 and determines the number of additional wavelengths (in this case, two wavelengths) included in the wavelength band corresponding to the removed existing wavelength. Subsequently, the extension determination / transmission level control unit 15 calculates the sum of the wavelength levels estimated to have been removed before the removal of the existing wavelengths (in this case, the wavelength level for one existing wavelength) (FIG. 3: ST7), a uniform target value in which the sum of the calculated wavelength levels is equal to the sum of the wavelength levels measured by the wavelength level monitor 10 corresponding to each of the specified optical transmitters is set to the wavelength level of the additional wavelength. Set as target value. More specifically, a value obtained by dividing the sum of the calculated wavelength levels by the number of additional wavelengths (in this case, two wavelengths) included in the wavelength band corresponding to the existing wavelength that has been removed is set as the target value (FIG. 3: ST8). In addition, the wavelength level estimated that the removed existing wavelength had before removal is stored in advance in the extension determination / transmission level control unit 15 or the wavelength level of the existing wavelength measured by the wavelength level monitor unit 10. It is estimated by the wavelength level or the like.

Further, as shown in FIG. 4B, when two or more existing wavelengths are removed, four additional wavelengths included in the wavelength band corresponding to the removed existing wavelengths (two wavelengths in this case). In this case, two additional wavelengths are substantially added. In this case, the extension determination / transmission level control unit 15 determines the number of additional wavelengths (four wavelengths in this case) included in the wavelength band corresponding to the removed existing wavelength (FIG. 3: ST6), and removes the existing wavelength that has been removed. Calculates the sum of the wavelength levels estimated to have existed before removal (in this case, the wavelength level for two existing wavelengths) (FIG. 3: ST7), and the existing wavelengths obtained by removing the sum of the calculated wavelength levels A value divided by the number of additional wavelengths included in the wavelength band corresponding to (in this case, 4 wavelengths) is set as a target value (FIG. 3: ST8).

Further, as shown in FIG. 4C, when the additional wavelength has already been added to the wavelength band adjacent to the wavelength band corresponding to the existing wavelength to be removed, the extension determination / transmission level control unit 15 sets the wavelength level. Based on each wavelength level in the wavelength multiplexed signal measured by the monitor unit 10, it is determined whether an additional wavelength has already been added to the wavelength band adjacent to the specified wavelength band (FIG. 3: ST4). As shown in FIG. 4C, the wavelength level measured by the wavelength level monitor unit 10 can be determined because it is lower than the existing wavelength when the additional wavelength is already added. it can. If an additional wavelength has already been added, a uniform target value is set including the optical transmitter of the wavelength band where the additional wavelength has already been added (FIG. 3: ST5). That is, an optical transmitter having an additional wavelength already added is identified from the wavelength level measured by the wavelength level monitor 10, and the number of additional wavelengths included in the wavelength band corresponding to the existing wavelength removed this time (in this case, 3 The number of added wavelengths (in this case, 7 wavelengths) is determined by adding the number of added wavelengths (in this case, 4 wavelengths) to (wavelength) (FIG. 3: ST6). In addition, the wavelength level estimated that the removed existing wavelength had before removal (in this case, the wavelength level corresponding to one wavelength of the existing wavelength) and the wavelength level of the added additional wavelength (in this case, the wavelength already added) (The wavelength level corresponding to the four additional wavelengths) is calculated (FIG. 3: ST7), and the sum of the calculated wavelength levels and the optical transmitters specified including the additional wavelengths already added are respectively determined. A uniform target value equal to the sum of the wavelength levels measured by the wavelength level monitor unit 10 is set as the target value of the wavelength level of the additional wavelength. More specifically, a value obtained by dividing the total sum of the calculated wavelength levels by the number of additional wavelengths determined in ST6 (in this case, 7 wavelengths) is set as a target value (FIG. 3: ST8). Note that the wavelength level of the added wavelength that has already been added has been previously set as the target value in the extension determination / transmission level control unit 15, so that the previously extracted target value is already added. It may be the wavelength level of the additional wavelength.

The extension determination / transmission level control unit 15 turns on the optical transmission unit specified for the existing wavelength among the optical transmission units 51 to 5n (FIG. 3: ST9), and the wavelength measured by the wavelength level monitoring unit 10 The optical output of the optical transmission signal output from the optical transmission unit specified so that the level becomes the set target value (including the optical transmission unit having the additional wavelength already added in FIG. 4C) The level is controlled (FIG. 3: ST10 to ST12).
In this way, the sum of the optical output levels of the additional wavelengths is controlled so as to be equal to the sum of the optical output levels of the existing wavelengths in the same wavelength band. It is possible to replace

  As described above, according to the first embodiment, when a part of the existing wavelengths is removed and the number of wavelengths is increased to a wavelength band corresponding to the removed existing wavelengths by increasing the number of the existing wavelengths removed. In addition, the existing wavelength and the wavelength band that have been removed, the identification of the optical transmission unit having the additional wavelength included in the identified wavelength band, and the wavelength measured by the wavelength level monitoring unit 10 corresponding to each of the identified optical transmission units Detection and calculation comprising setting the target value of the level and controlling the optical output level of the optical transmission signal output from the optical transmitter specified so that the wavelength level measured by the wavelength level monitor unit 10 becomes the target value In addition, since it is possible to automatically perform the control, it is possible to suppress the influence on the existing wavelength due to the wavelength insertion error or the light output level adjustment error caused by manual operation as in the prior art. Moreover, since it controls automatically, it can extend in a short time rather than implementing manually. Further, since no control is performed only by removing the existing wavelength, there is an effect that the wavelength can be added to the existing wavelength multiplexing transmission system with almost no restrictions.

  Further, the sum of the wavelength levels estimated that the existing wavelength that has been removed had before removal is equal to the sum of the wavelength levels measured by the wavelength level monitor unit 10 corresponding to each identified optical transmission unit. Since the uniform target value is set, there is an effect that the influence on the transmission quality of the remaining existing wavelength can be further suppressed.

  In addition, when an additional wavelength is already added to the wavelength band adjacent to the specified wavelength band, the optical output level is uniformly controlled including the added additional wavelength, so the transmission quality of the remaining existing wavelength This has the effect of further suppressing the impact on

Embodiment 2. FIG.
FIG. 5 is a block diagram showing a configuration of a wavelength division multiplexing transmission system having a wavelength extension system according to Embodiment 2 of the present invention. In FIG. 5, the wavelength extension system is a receiving BER (bit error rate) at the receiving side. The monitor unit (bit error rate monitor means) 17 measures the bit error rate of each optical reception signal input by the optical receivers 131 to 13n for the additional wavelength. On the transmission side, the extension determination / transmission level control unit (addition determination / transmission level control means) 18 outputs from the specified optical transmission unit so that the bit error rate measured by the reception BER monitor unit 17 is uniform. The optical output level of the transmitted optical transmission signal is controlled. Other configurations are the same as those in FIG.

Next, the operation will be described.
FIG. 6 is a flowchart showing a wavelength extension procedure according to the second embodiment of the present invention, and will be described below with reference to FIGS.

The difference from the first embodiment is that a reception BER monitor unit 17 is provided on the reception side. In the first embodiment, the optical output level in the optical transmitter of the additional wavelength is set as a target value that is obtained by equally dividing the sum of the optical output levels of the removed existing wavelengths by the number of additional wavelengths. In the second embodiment, the reception BER of each additional wavelength is measured by the reception BER monitor unit 17, and the reception BER of each additional wavelength measured by the addition determination / transmission level control unit 18 is monitored (FIG. 6: ST13). ) Re-set the target value of the optical output level with a deviation so that the reception BER of each additional wavelength to be monitored is uniform (FIG. 6: ST14, ST15), and calculate the sum of the optical output levels of the additional wavelengths. Control is performed so that the reception BER of each additional wavelength is uniform while keeping the total optical output level of the existing wavelengths equal.

As described above, according to the second embodiment, the wavelength multiplexed signal is controlled by controlling the optical output level of each additional wavelength on the transmission side so that the bit error rate of each additional wavelength on the reception side is uniform. The transmission quality can be further improved.

  DESCRIPTION OF SYMBOLS 1 Existing wavelength multiplexing apparatus transmission part, 2 Optical repeater, 3 Existing wavelength multiplexing apparatus receiving part, 51-5n Optical transmission part for additional wavelengths (optical transmission means), 6 Optical multiplexing part (1st optical multiplexing means), 7 optical coupler (second optical multiplexing means), 8 optical amplifier (optical amplification means), 9 optical coupler (first optical branching means), 10 wavelength level monitoring unit (wavelength level monitoring means), 11 optical coupler (first optical coupling means) 2 optical branching unit), 12 optical demultiplexing unit (optical demultiplexing unit), 131 to 13n optical receiving unit for additional wavelength (optical receiving unit), 15, 18 additional determination / transmission level control unit (addition determination / transmission) Level control means), 17 reception BER monitor section (bit error rate monitor means).

Claims (4)

When a part of the existing wavelengths in the existing wavelength division multiplexing transmission system is removed, the wavelength is added to the wavelength band corresponding to the removed existing wavelength by increasing the number of the existing wavelengths that have been removed. In a wavelength division multiplexing transmission system equipped with a system,
The above wavelength extension system
A plurality of additional wavelength optical transmission means for outputting optical transmission signals of different wavelengths set at a wavelength interval narrower than the existing wavelength in the existing wavelength multiplexing transmission system;
First optical multiplexing means for multiplexing optical transmission signals output from the plurality of optical transmission means;
Second optical multiplexing means for multiplexing the optical transmission signal combined by the first optical multiplexing means with the wavelength multiplexed signal in the existing wavelength multiplexing transmission system;
Optical amplification means for amplifying the wavelength multiplexed signal combined by the second optical multiplexing means;
First optical branching means for branching a part of the wavelength multiplexed signal output from the optical amplification means;
Wavelength level monitoring means for measuring each wavelength level in the wavelength multiplexed signal branched by the first optical branching means;
Based on each wavelength level in the wavelength multiplexed signal measured by the wavelength level monitoring means, the existing wavelength removed in the existing wavelength multiplexing transmission system and its wavelength band are specified, and the identification of the optical transmission means The optical transmission means having the additional wavelengths included in the specified wavelength band are specified, and the target value of the wavelength level measured by the wavelength level monitoring means corresponding to each of the specified optical transmission means is set to be uniform. And an extension determination / transmission level control means for controlling the optical output level of the optical transmission signal output from the specified optical transmission means so that the wavelength level measured by the wavelength level monitoring means becomes the target value. A wavelength division multiplexing transmission system. Wavelength extension system
A second optical branching unit for branching an optical reception signal of an additional wavelength among the wavelength multiplexed signals at the reception side in the existing wavelength division multiplexing transmission system;
Optical demultiplexing means for demultiplexing the optical reception signals branched by the second optical branching means into different wavelengths;
A plurality of additional wavelength optical receiving means for inputting optical reception signals of different wavelengths respectively demultiplexed by the optical demultiplexing means;
Bit error rate monitoring means for measuring the bit error rate of each optical reception signal input by the plurality of optical reception means,
The extension determination / transmission level control means is
2. The wavelength division multiplexing according to claim 1, wherein the optical output level of the optical transmission signal output from the optical transmission means specified so that the bit error rate measured by the bit error rate monitoring means is uniform is controlled. Transmission system. The extension determination / transmission level control means is
A uniform target for equalizing the sum of the wavelength levels estimated to have existed in the removed existing wavelengths before removal and the sum of the wavelength levels measured by the wavelength level monitoring means corresponding to each of the specified optical transmission means 3. The wavelength division multiplexing transmission system according to claim 1, wherein a value is set. The extension determination / transmission level control means is
Based on each wavelength level in the wavelength multiplexed signal measured by the wavelength level monitoring means, it is determined whether an additional wavelength has already been added to the wavelength band adjacent to the specified wavelength band. In addition, the optical transmission means having the added wavelength already added in the existing wavelength multiplex transmission system is specified, and the wavelength level estimated that the removed existing wavelength had before removal and the wavelength of the added wavelength already added. A uniform target value is set so that the sum of the levels is equal to the sum of the wavelength levels measured by the wavelength level monitoring means corresponding to each of the optical transmission means specified including the added additional wavelengths. Specified including the additional wavelengths already added so that the wavelength level measured by the wavelength level monitoring means becomes the target value. Claim 1 or claim 2 wavelength multiplexing transmission system, wherein the controlling the light output level of the optical transmission signal outputted from the light transmitting means.

Images