JP3907939B2 - Inverse wavelength division multiplexing optical transmission system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inverse wavelength division multiplexing optical transmission system that divides and transmits a tributary signal having a high speed and a large capacity compared to the optical transmission signal speed into the optical transmission signals having a plurality of wavelengths.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a wavelength division multiplexing optical transmission system is known in which a plurality of optical signals having different wavelengths are wavelength-multiplexed and large-capacity transmission is performed using one optical fiber. FIG. 13 is a diagram showing the configuration of this conventional wavelength division multiplexing optical transmission system.
[0003]
In FIG. 13, tributary optical input signals S1 to Sn input to the optical transmitter 101 are converted into optical signals having different wavelengths λ1 to λn, respectively. The optical signal output from the optical transmitter 101 is wavelength-multiplexed by the optical wavelength multiplexer 102 and output to the optical transmission line 103 as a wavelength-multiplexed optical signal. The wavelength multiplexed optical signal is relayed in multiple stages by a plurality of optical fiber amplification repeaters 104 and transmitted over a long distance. The optical wavelength demultiplexing device 105 demultiplexes the wavelength-division multiplexed optical signal transmitted over a long distance for each wavelength, and outputs it to the optical receiving device 106 as optical signals of different wavelengths λ1 to λn. The optical receiver 106 performs reception processing on the optical signals having the wavelengths λ1 to λn, and outputs tributary optical output signals S1 to Sn.
[0004]
[Problems to be solved by the invention]
By the way, in the conventional wavelength division multiplexing optical transmission system described above, for example, when the transmission rate of the tributary signals S1 to Sn is 2.5 Gbit / s, a large capacity can be obtained by wavelength multiplexing transmission of a 2.5 Gbit / s optical signal. Long-distance transmission can be realized.
[0005]
However, for example, when the transmission speed of the tributary signal is 10 Gbit / s, the transmission speed is four times that of the optical signal, so that the transmission distance is shorter than when the transmission speed is 2.5 Gbit / s. There was a point.
[0006]
The present invention has been made in view of the above, and an object of the present invention is to obtain an inverse wavelength multiplexed optical transmission system capable of long-distance transmission even when the speed of a tributary signal is increased.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an inverse wavelength division multiplexing optical transmission system according to the present invention converts a tributary signal having a high speed and a large capacity into a plurality of wavelengths as compared with an optical transmission signal speed transmitted from a transmission side apparatus to a reception side apparatus. In the inverse wavelength division multiplexing optical transmission system that divides and transmits the optical transmission signal, the transmission side device includes a demultiplexing circuit that demultiplexes a tributary signal, and a plurality of demultiplexed signals that are demultiplexed by the demultiplexing circuit A plurality of transmission frame generating circuits for assembling a plurality of transmission frames, and an electro-optical conversion circuit for converting the plurality of transmission frames into optical signals having different wavelengths, respectively, and the receiving-side device is connected via the optical transmission path. A plurality of photoelectric conversion circuits for converting the optical signals having different wavelengths input into a plurality of electrical signals corresponding to the respective wavelengths; A plurality of transmission frame termination circuits that perform reception processing of each transmission frame corresponding to each electrical signal converted by the electrical conversion circuit and output a demultiplexed signal in which a delay difference between the transmission frames is corrected; and A multiplexing circuit that multiplexes a plurality of demultiplexed signals output from the transmission frame termination circuit and outputs the tributary signal, and The transmission frame generation circuit includes a delay absorption memory that absorbs a transmission delay difference between wavelengths, and corrects the delay difference between the transmission frames in advance by the delay absorption memory. It is characterized by that.
[0008]
According to the present invention, in the transmission side device, the demultiplexing circuit demultiplexes the tributary signal, and the transmission frame generation circuit outputs a plurality of transmission frames for the plurality of demultiplexed signals demultiplexed by the demultiplexing circuit. Assembling, the electro-optical conversion circuit converts the plurality of transmission frames into optical signals having different wavelengths, and the optical signals are combined and output onto the optical transmission path. The optical signals having different wavelengths input through the optical transmission path are converted into a plurality of electrical signals corresponding to the respective wavelengths, and the transmission frame termination circuit corresponds to the respective electrical signals converted by the respective photoelectric conversion circuits. Each transmission frame is received, a demultiplexed signal in which the delay difference between the transmission frames is corrected is output, and the multiplexing circuit is connected to a plurality of transmission frame termination circuits. A plurality of demultiplexing signals output from the multiplexed output the tributary signals The transmission frame generation circuit includes a delay absorption memory that absorbs a transmission delay difference between wavelengths, and can correct a delay difference between the transmission frames by the delay absorption memory in advance to absorb a large delay difference. I am doing so.
[0009]
In an inverse wavelength division multiplexing optical transmission system according to a next invention, in the above invention, the transmission frame termination circuit includes a delay absorption memory that absorbs a transmission delay difference between wavelengths, and the delay absorption memory allows the transmission frames to be transmitted between the transmission frames. The delay difference is corrected.
[0010]
According to this invention, the transmission frame termination circuit has a delay absorption memory that absorbs a transmission delay difference between wavelengths, and the delay absorption memory corrects the delay difference between the transmission frames.
[0011]
The inverse wavelength division multiplexing optical transmission system according to the next invention is the above-mentioned invention, wherein the receiving side device further comprises an optical wavelength demultiplexing device for optical wavelength separation of optical signals having different wavelengths for transmitting the plurality of transmission frames. The optical wavelength demultiplexing device includes an optical fiber that compensates for a delay between optical signals having different wavelengths.
[0012]
According to this invention, the optical fiber in the optical wavelength demultiplexing device of the receiving side device compensates for the delay between optical signals having different wavelengths.
[0015]
The inverse wavelength division multiplexing optical transmission system according to the next invention is In an inverse wavelength division multiplexing optical transmission system that transmits a high-speed and large-capacity tributary signal divided into a plurality of optical transmission signals having a plurality of wavelengths compared to the optical transmission signal speed transmitted from the transmission-side device to the reception-side device, The transmission side device includes: a demultiplexing circuit that demultiplexes a tributary signal; a plurality of transmission frame generation circuits that assemble a plurality of transmission frames for a plurality of demultiplexed signals that are demultiplexed by the demultiplexing circuit; An electro-optical conversion circuit that converts transmission frames into optical signals having different wavelengths, and the reception-side device includes a plurality of optical signals having different wavelengths that are input via the optical transmission path. A plurality of photoelectric conversion circuits that convert electrical signals, and the reception process of each transmission frame corresponding to each electrical signal converted by each photoelectric conversion circuit A plurality of transmission frame termination circuits that respectively output demultiplexed signals in which delay differences between transmission frames are corrected, and a plurality of demultiplexing signals output from the plurality of transmission frame termination circuits are multiplexed to produce the tributary A multiplexing circuit for outputting a signal, The transmission frame termination circuit includes a first delay absorption memory that absorbs a transmission delay difference between wavelengths, and the transmission frame generation circuit includes a second delay absorption memory that absorbs a transmission delay difference between wavelengths, Detecting means for detecting a delay difference between the wavelengths in the receiving side device; and determining whether the first delay absorption memory can absorb the delay difference between the wavelengths based on a detection result of the detecting means. And an adjustment control means for performing control to adjust the delay amount between the wavelengths by the second delay absorption memory when the determination means determines that the delay difference between the wavelengths cannot be absorbed. It is characterized by that.
[0016]
According to the present invention, the detecting means detects a delay difference between the wavelengths in the receiving-side apparatus, and the judging means determines that the first delay absorption memory is between the wavelengths based on the detection result of the detecting means. If the adjustment control unit determines that the determination unit cannot absorb the delay difference between the wavelengths, the amount of delay between the wavelengths by the second delay absorption memory is determined. The control which adjusts is performed.
[0017]
The inverse wavelength division multiplexing optical transmission system according to the next invention is In an inverse wavelength division multiplexing optical transmission system that transmits a high-speed and large-capacity tributary signal divided into a plurality of optical transmission signals having a plurality of wavelengths compared to the optical transmission signal speed transmitted from the transmission-side device to the reception-side device, The transmission side device includes: a demultiplexing circuit that demultiplexes a tributary signal; a plurality of transmission frame generation circuits that assemble a plurality of transmission frames for a plurality of demultiplexed signals that are demultiplexed by the demultiplexing circuit; An electro-optical conversion circuit that converts transmission frames into optical signals having different wavelengths, and the receiving-side device includes a plurality of optical signals having different wavelengths that are input via the optical transmission path. A plurality of photoelectric conversion circuits for converting into electrical signals of each and reception of each transmission frame corresponding to each electrical signal converted by each photoelectric conversion circuit A plurality of transmission frame termination circuits each outputting a demultiplexed signal in which a delay difference between transmission frames is corrected, and a plurality of demultiplexing signals output from the plurality of transmission frame termination circuits are multiplexed to A multiplexing circuit that outputs a tributary signal, The transmission frame generation circuit includes a delay absorption memory that absorbs a transmission delay difference between wavelengths, and includes a detection unit that detects a delay difference between wavelengths in the reception side device, and a delay difference detected by the detection unit. And adjusting control means for adjusting the delay amount of each wavelength by the delay absorption memory and correcting the delay difference.
[0018]
According to this invention, the detection means detects a delay difference between the wavelengths in the receiving-side apparatus, and the adjustment control means detects each wavelength by the delay absorption memory based on the delay difference detected by the detection means. Control for correcting the delay difference is performed by adjusting the delay amount.
[0021]
In the inverse wavelength division multiplexing optical transmission system according to the next invention, in the above invention, the transmission side device transmits each transmission frame group generated corresponding to each tributary signal of the plurality of input tributary signals to the adjacent wavelength. It is characterized by being assigned to a wavelength within the group for transmission.
[0022]
According to the present invention, the transmission-side apparatus assigns each transmission frame group generated corresponding to each tributary signal of the plurality of input tributary signals to the wavelength in the adjacent wavelength group, and transmits it by dispersion compensation. The delay difference is made small.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of an inverse wavelength division multiplexing optical transmission system according to the present invention will be described below with reference to the accompanying drawings.
[0024]
Embodiment 1 FIG.
First, a first embodiment of the present invention will be described. FIG. 1 is a diagram showing a schematic configuration of an inverse wavelength division multiplexing optical transmission system according to Embodiment 1 of the present invention. In FIG. 1, tributary optical input signals S1 to Sm input to the optical transmitter 1 are converted into optical signals having different wavelengths λ1 to λn, respectively. This optical signal is wavelength-multiplexed by the optical wavelength multiplexer 2 and output to the optical transmission line 3 as a wavelength-multiplexed optical signal. The optical fiber amplifying repeater 4 relays the wavelength multiplexed optical signal in multiple stages and transmits it over a long distance. The optical wavelength demultiplexing device 5 demultiplexes the wavelength-division multiplexed optical signal transmitted over a long distance for each wavelength and outputs it to the optical receiving device 6. The optical receiver 6 performs reception processing on each wavelength and outputs tributary light output signals S1 to Sm.
[0025]
FIG. 2 is a block diagram showing a configuration of the optical transmission device 1 shown in FIG. 2 shows a configuration in which the number m of tributary optical input signals is “1” and the number of wavelength multiplexing n is “4”. In FIG. 2, the photoelectric conversion circuit 11 converts the input tributary light input signal S <b> 1 into an electric signal and outputs it to the demultiplexing circuit 12. The demultiplexing circuit 12 separates the signal converted into the electric signal into four signals, and outputs them to the first to fourth frame generation circuits 13 to 16, respectively. The first to fourth frame generation circuits 13 to 16 assemble transmission frames, which will be described later, and output them to the electro-optical conversion circuits 17 to 20. The electro-optical conversion circuits 17 to 20 are respectively connected to the first to fourth frame generation circuits 13 to 16, and the transmission frames input from the first to fourth frame generation circuits 13 to 16 are transmitted with wavelengths λ1 to λ1, respectively. It converts to an optical signal of λ4 and outputs it to the optical wavelength multiplexer 2.
[0026]
FIG. 3 is a block diagram illustrating a configuration of the first to fourth frame generation circuits 13 to 16. In FIG. 3, one demultiplexed signal output from the demultiplexing circuit 12 is input to the speed conversion circuit 31. The speed conversion circuit 31 converts the speed of this demultiplexed signal, and transmits overhead information and error correction codes. Each redundant area is added and output to the overhead information generation circuit 32. The overhead information generation circuit 32 stores the overhead information in the overhead information area of the signal output from the speed conversion circuit 31 and outputs it to the error correction encoding circuit 33. The error correction coding circuit 33 performs error correction coding of the signal output from the overhead information generation circuit 32, stores the redundant information resulting from the error correction coding in the error correction code area, and transmits it as a transmission frame. It outputs to the corresponding electro-optical conversion circuits 17-20.
[0027]
FIG. 4 is a diagram illustrating an example of the FEC frame processed by the first to fourth frame generation circuits 13 to 16 illustrated in FIG. 3. This FEC frame is, for example, ITU-T G.264. 975 recommendation. In the speed conversion circuit 31, as shown in FIG. 4A, an OH (overhead) region E1 and an RS (255, 239) redundant region E2 are added. As shown in FIG. 4B, each of the overhead information generation circuit 32 and the error correction encoding circuit 33 has overhead information “0H1” to “0H1” in the corresponding OH area E1 and RS (255, 239) redundant area. OH16 "and error correction code redundancy information" R0-0 "to" R15-15 "are stored. Here, the demultiplexed signals that have been demultiplexed into four are framed by the first to fourth frame generation circuits 13 to 16 in order from “0-1” of the frame. As the error correction code, a Reed-Solomon code RS (255, 239) code is used. And RS (255, 239) codes “0” (“R0-0” to “R0-15”) to “8” (“R15-0” to “R15-15”), which are the results, are generated. ,Store. In addition, since the quality after optical transmission can be improved by performing error correction coding, a wavelength division multiplexing optical transmission system capable of further long-distance transmission can be constructed.
[0028]
On the other hand, FIG. 5 is a block diagram showing a configuration of the optical receiver 6 shown in FIG. In FIG. 5, the photoelectric conversion circuits 21 to 24 convert optical signals having wavelengths λ1 to λ4 input from the optical wavelength demultiplexing device 5 into electrical signals. The first to fourth frame termination circuits 25 to 28 are connected to the photoelectric conversion circuits 21 to 24, respectively, and transmit frame processing such as error correction decoding processing and overhead information separation processing from input optical signals. And output to the multiplexing circuit 29. The multiplexing circuit 29 multiplexes the signals input from the first to fourth frame termination circuits 25 to 28 and restores one tributary signal. The electro-optical conversion circuit 30 converts the one tributary signal into an optical signal. And output as a tributary signal S1.
[0029]
FIG. 6 is a block diagram illustrating an example of the configuration of the first to fourth frame termination circuits 25 to 28. In FIG. 6, a frame synchronization circuit 41 detects a frame synchronization pattern (not shown) stored as overhead information of the transmission frame shown in FIG. 4, and detects the start position of the transmission frame. The error correction decoding circuit 42 performs error correction decoding of the transmission frame based on the start position of the transmission frame detected by the frame synchronization circuit 41 and corrects the bit error generated in the optical transmission path 3. The overhead information termination circuit 43 performs processing necessary for maintenance and operation of the optical transmission line based on the overhead information. The delay compensation memory 44 absorbs the delay of the optical transmission path 3 with respect to the frame signal output from the overhead information termination circuit 43 and outputs it to the speed conversion circuit 45. The speed conversion circuit 45 outputs the demultiplexed signal obtained by deleting the overhead information area E1 and the error correction code redundant area E2 to the multiplexing circuit 29 from the frame to which the delay is added.
[0030]
As described above, the first to fourth frame termination circuits 25 to 28 have the delay compensation memory 44 and absorb the transmission delay difference between frames transmitted by the wavelengths λ1 to λ4.
[0031]
Here, the reason why a large delay difference occurs between optical signals having wavelengths λ1 to λ4 will be described with reference to FIG. FIG. 7 is a block diagram showing an example of the configuration of the optical wavelength demultiplexing device 5 shown in FIG. In FIG. 7, the optical multiplexed signal input to the optical demultiplexer 51 is demultiplexed into optical signals of wavelengths λ1 to λ4 and input to the dispersion compensators 52 to 55, respectively. The optical signal transmitted over a long distance in the optical fiber that is the optical transmission line 3 has a waveform distortion due to the dispersion characteristic of the optical fiber, and the waveform distortion is corrected by compensating the distortion with the opposite dispersion characteristic. This enables long distance transmission. Generally, a dispersion compensator is composed of an optical fiber for dispersion compensation. Since the amount of dispersion generated in the optical transmission line depends on the optical wavelength, the optical fiber length for dispersion compensation with respect to the wavelengths λ1 to λ4 is different, which causes a large transmission delay. The transmission delay difference generated between the wavelengths λ1 to λ4 is absorbed by the delay compensation memory 44, respectively.
[0032]
For example, in each of the delay compensation memories 44 of the first to fourth frame termination circuits 25 to 28, the transmission frames are written in the memories at different phases, and the transmission frames are read out at the same phase. The phase of the transmission frame can be made uniform. Since the transmission frames having the same phase are subjected to speed conversion and multiplexed, the four demultiplexed signals transmitted by the optical signals having the wavelengths λ1 to λ4 are converted into the original tributary signals. It can be restored.
[0033]
Here, the case where the delay difference is caused by the optical fiber for dispersion compensation has been described. However, for example, when the transmission path of each wavelength is different, the transmission delay difference is caused. The delay compensation memory 44 absorbs the delay difference, so that the tributary signal can be transmitted at a plurality of different wavelengths.
[0034]
In the first embodiment described above, the delay compensation memory 44 is provided in the first to fourth frame termination circuits 25 to 28 with respect to the respective transmission light wavelengths λ1 to λ4, and this occurs due to dispersion compensation or a difference in the path of each transmission optical signal. Since the transmission delay difference between the wavelengths λ1 to λ4 can be absorbed, one tributary signal can be divided into a plurality of optical wavelength signals and transmitted over a long distance.
[0035]
Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. FIG. 8 is a block diagram showing the configuration of the optical wavelength demultiplexing device in the inverse wavelength multiplexing optical system according to the second embodiment of the present invention. The optical wavelength demultiplexing device shown in FIG. 8 is provided with delay compensators 56 to 59 each composed of an optical fiber for delay compensation after the dispersion compensators 52 to 55 shown in FIG. . Other configurations are the same as those of the first embodiment.
[0036]
According to the second embodiment, even if a large transmission delay difference that cannot absorb the delay occurs due to the memory capacity limitation of the delay compensation memory 44, the delay compensators 56 to 59 perform this transmission. The delay difference can be absorbed and the circuit scale of the optical receiver 6 can be reduced.
[0037]
Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described. FIG. 9 is a block diagram showing configurations of the first to fourth frame generation circuits in the inverse wavelength division multiplexing optical transmission system according to the third embodiment of the present invention. In FIG. 9, the first to fourth frame generation circuits are connected to a delay compensation memory 64 in the subsequent stage of the error correction coding circuit 33 constituting the first to fourth frame generation circuits 13 to 16 shown in FIG. Is provided. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same components.
[0038]
Generally, in the first to fourth frame generation circuits 13 to 16 and the first to fourth frame termination circuits 25 to 28, the first to fourth frame termination circuits 25 to 28 are larger in circuit scale. For this reason, if the memory capacity of the delay compensation memory 44 provided in the first to fourth frame termination circuits 25 to 28 is increased, mounting on the optical receiver 6 becomes difficult.
[0039]
Therefore, in the third embodiment, the first to fourth frame generation circuits 13 to 16 are provided with a delay compensation memory 64, and a predetermined delay is added on the transmission side in advance, so that the delay absorption required on the reception side is obtained. The amount can be dispersed. As a result, a larger transmission delay difference can be absorbed.
[0040]
Here, the control processing procedure of the delay compensation memory 64 will be described with reference to the flowchart shown in FIG. In FIG. 10, a delay difference detection unit (not shown) of the optical receiver 6 determines whether or not the delay compensation memory 44 can absorb the transmission delay difference (step S101). When the transmission delay difference can be absorbed by the delay compensation memory 44 (step S101, YES), this processing is terminated as it is, and when the transmission delay difference cannot be absorbed by the delay compensation memory 44 (step S101, NO) is set to insert a delay for a wavelength with a small delay in the delay compensation memory 64 on the optical transmission apparatus 1 side (step S102), and this process is terminated.
[0041]
In this way, when the delay difference cannot be completely absorbed by the delay compensation memory 44 on the reception side, a delay is added to the delay compensation memory 64 for a wavelength with a small delay on the transmission side, and the delay on the reception side at each wavelength Make sure the amount is about the same.
[0042]
FIG. 11 is a flowchart showing another control processing procedure of the delay compensation memory 64. In FIG. 11, a delay difference detector (not shown) of the optical receiver 6 detects a transmission delay difference on the receiving side (step S201). Thereafter, it is determined whether or not the transmission delay difference can be absorbed by the delay compensation memory 44 (step S202). When the transmission delay difference can be absorbed by the delay compensation memory 44 (step S202, YES), this processing is terminated as it is, and when the transmission delay difference cannot be absorbed by the delay compensation memory 44 (step S202, step S202). NO) is set to insert a delay for a wavelength with a small delay in the delay compensation memory 64 on the optical transmission apparatus 1 side (step S203), and this process is terminated.
[0043]
In the control processing procedure shown in FIG. 11, since the delay amount of the delay difference is not detected, the delay amount added to the delay compensation memory 64 is sequentially adjusted. On the other hand, in the control processing procedure shown in FIG. 12, since the delay amount of the delay difference is detected, the delay amount added to the delay compensation memory 64 can be collectively corrected for each wavelength. Note that transmission of delay compensation amount information to the transmission side is performed using overhead information of a transmission frame. The delay amount can be measured by defining a delay amount measurement code in the overhead information.
[0044]
Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described. FIG. 12 is a schematic diagram showing a wavelength arrangement when two tributary signals S1 and S2 are transmitted by eight types of optical wavelength signals λ1 to λ8. As shown in FIG. 12, the delay difference due to dispersion compensation can be reduced by using groups having close wavelengths for each of the tributary signals S1 and S2. As a result, the memory capacity of the delay compensation memories 44 and 64 can be reduced.
[0045]
【The invention's effect】
As described above, according to the present invention, in the transmission side device, the demultiplexing circuit demultiplexes the tributary signal, and the transmission frame generation circuit demultiplexes the demultiplexed signals by the demultiplexing circuit. Assembling a plurality of transmission frames, the electro-optical conversion circuit converts the plurality of transmission frames into optical signals having different wavelengths, and the optical signals are combined and output onto the optical transmission path. The photoelectric conversion circuit converts the optical signals having different wavelengths input via the optical transmission path into a plurality of electrical signals corresponding to the respective wavelengths, and the transmission frame termination circuit is converted by each photoelectric conversion circuit. Receives each transmission frame corresponding to each electrical signal, outputs a demultiplexed signal in which the delay difference between each transmission frame is corrected, and includes a plurality of multiplexing circuits. A plurality of demultiplexing signals outputted from the transmission frame termination circuit multiplexes outputs the tributary signal The transmission frame generation circuit includes a delay absorption memory that absorbs a transmission delay difference between wavelengths, and can correct a delay difference between the transmission frames by the delay absorption memory in advance to absorb a large delay difference. So, even high-speed and large-capacity tributary signals can be transmitted over long distances, In addition, it is possible to realize an inverse wavelength division multiplexing optical transmission system that enables long-distance transmission, and to reduce the circuit scale of the receiving device. There is an effect.
[0046]
According to the next invention, the transmission frame termination circuit has a delay absorption memory that absorbs a transmission delay difference between wavelengths, and the delay absorption memory corrects the delay difference between the transmission frames. In addition, there is an effect that it is possible to realize an inverse wavelength multiplexing optical transmission system that enables long-distance transmission.
[0047]
According to the next invention, since the optical fiber in the optical wavelength demultiplexing device of the receiving side device compensates for the delay between optical signals having different wavelengths, the inverse wavelength that enables further long-distance transmission. The multiplexed optical transmission system can be realized and the circuit scale of the receiving side device can be reduced.
[0049]
According to the next invention, the detecting means detects a delay difference between the wavelengths in the receiving-side apparatus, and the judging means is configured such that the first delay absorption memory is based on the detection result of the detecting means. When the adjustment control unit determines that the determination unit cannot absorb the delay difference between the wavelengths, the delay between the wavelengths by the second delay absorption memory is determined. Since the control for adjusting the amount is performed, it is possible to realize an inverse wavelength division multiplexing optical transmission system that enables long-distance transmission and to reduce the circuit scale of the receiving side device. Play.
[0050]
According to the next invention, the detection means detects a delay difference between the wavelengths in the receiving-side apparatus, and the adjustment control means detects each wavelength by the delay absorption memory based on the delay difference detected by the detection means. Since the control is performed to adjust the delay amount to correct the delay difference, it is possible to realize an inverse wavelength division multiplexing optical transmission system that enables long-distance transmission, and the circuit scale of the receiving side device There is an effect that can be reduced.
[0052]
According to the next invention, the transmission-side apparatus assigns each transmission frame group generated corresponding to each tributary signal of the plurality of input tributary signals to the wavelength in the adjacent wavelength group, and transmits it. Since the delay difference due to is reduced, the memory capacity of the delay absorbing memory can be reduced, and the circuit scale on the receiving side can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an inverse wavelength division multiplexing optical transmission system according to a first embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of the optical transmission device illustrated in FIG. 1;
3 is a block diagram showing a configuration of first to fourth frame generation circuits shown in FIG. 2. FIG.
FIG. 4 is a diagram illustrating a configuration of a transmission frame.
FIG. 5 is a block diagram showing a configuration of the optical receiving apparatus shown in FIG. 1;
6 is a block diagram showing a configuration of first to fourth frame termination circuits shown in FIG. 1; FIG.
7 is a block diagram showing a configuration of the optical wavelength demultiplexing device shown in FIG. 1; FIG.
FIG. 8 is a block diagram showing a configuration of an optical wavelength demultiplexing device of an inverse wavelength division multiplexing optical transmission system according to a second embodiment of the present invention.
FIG. 9 is a block diagram showing a configuration of first to fourth frame generation circuits of an inverse wavelength division multiplexing optical transmission system according to a third embodiment of the present invention.
10 is a flowchart showing a delay compensation control processing procedure by the inverse wavelength division multiplexing optical transmission system shown in FIG. 9;
11 is a flowchart showing another delay compensation control processing procedure by the inverse wavelength multiplexing optical transmission system shown in FIG. 9;
FIG. 12 is a schematic diagram showing a wavelength arrangement of a tributary signal according to the fourth embodiment of the present invention.
FIG. 13 is a diagram showing a schematic configuration of a conventional wavelength division multiplexing optical transmission system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical transmitter, 2 Optical wavelength multiplexer, 3 Optical transmission line, 4 Optical fiber amplification repeater, 5 Optical wavelength demultiplexer, 6 Optical receiver, 11, 21-24 Photoelectric conversion circuit, 12 Demultiplexing circuit , 13-16 First to fourth frame generation circuits, 17-20, 30 Electro-optical conversion circuit, 25-28 First to fourth frame termination circuits, 29 Multiplexing circuit, 31, 45 Speed conversion circuit, 32 Overhead information generation circuit, 33 error correction coding circuit, 41 frame synchronization circuit, 42 error correction decoding circuit, 43 overhead information termination circuit, 44, 64 delay compensation memory, 51 optical demultiplexer, 52-55 dispersion compensator, 56-59 Delay compensator.

Claims (6)

In an inverse wavelength division multiplexing optical transmission system that divides and transmits a tributary signal having a high speed and a large capacity compared to the optical transmission signal speed transmitted from the transmission side device to the reception side device into the optical transmission signals of a plurality of wavelengths,
The transmitting device is:
A demultiplexing circuit for demultiplexing the tributary signal;
A plurality of transmission frame generating circuits for assembling a plurality of transmission frames for a plurality of demultiplexed signals demultiplexed by the demultiplexing circuit;
An electro-optical conversion circuit that converts the plurality of transmission frames into optical signals having different wavelengths, and
With
The receiving side device
A plurality of photoelectric conversion circuits for converting optical signals having different wavelengths input via the optical transmission path into a plurality of electrical signals corresponding to the respective wavelengths;
A plurality of transmission frame termination circuits that perform reception processing of each transmission frame corresponding to each electrical signal converted by each photoelectric conversion circuit and output a demultiplexed signal that corrects a delay difference between each transmission frame, and
A multiplexing circuit that multiplexes a plurality of demultiplexed signals output from the plurality of transmission frame termination circuits and outputs the tributary signal;
And the transmission frame generation circuit includes a delay absorption memory that absorbs a transmission delay difference between wavelengths, and the delay wavelength multiplexing corrects the delay difference between the transmission frames in advance by the delay absorption memory. Optical transmission system.   The inverse transmission frame according to claim 1, wherein the transmission frame termination circuit includes a delay absorption memory that absorbs a transmission delay difference between wavelengths, and corrects the delay difference between the transmission frames by the delay absorption memory. Wavelength multiplexing optical transmission system. The receiving side device further includes an optical wavelength demultiplexing device that separates optical signals having different wavelengths for transmitting the plurality of transmission frames.
The inverse wavelength division multiplexing optical transmission system according to claim 1, wherein the optical wavelength demultiplexing device includes an optical fiber that compensates for a delay between optical signals having different wavelengths. In an inverse wavelength division multiplexing optical transmission system that divides and transmits a tributary signal having a high speed and a large capacity compared to the optical transmission signal speed transmitted from the transmission side device to the reception side device into the optical transmission signals of a plurality of wavelengths,
The transmitting device is:
A demultiplexing circuit for demultiplexing the tributary signal;
A plurality of transmission frame generating circuits for assembling a plurality of transmission frames for a plurality of demultiplexed signals demultiplexed by the demultiplexing circuit;
An electro-optical conversion circuit that converts the plurality of transmission frames into optical signals having different wavelengths, and
With
The receiving side device
A plurality of photoelectric conversion circuits for converting optical signals having different wavelengths input via the optical transmission path into a plurality of electrical signals corresponding to the respective wavelengths;
A plurality of transmission frame termination circuits that perform reception processing of each transmission frame corresponding to each electrical signal converted by each photoelectric conversion circuit and output a demultiplexed signal that corrects a delay difference between each transmission frame, and
A multiplexing circuit that multiplexes a plurality of demultiplexed signals output from the plurality of transmission frame termination circuits and outputs the tributary signal;
With
The transmission frame termination circuit includes a first delay absorption memory that absorbs a transmission delay difference between wavelengths,
The transmission frame generation circuit includes a second delay absorption memory that absorbs a transmission delay difference between wavelengths,
Detecting means for detecting a delay difference between each wavelength in the receiving side device;
Determining means for determining whether or not the first delay absorption memory can absorb a delay difference between wavelengths based on a detection result of the detection means;
An adjustment control means for performing control to adjust a delay amount between the wavelengths by the second delay absorption memory when the determination means determines that the delay difference between the wavelengths cannot be absorbed;
An inverse wavelength division multiplexing optical transmission system. In an inverse wavelength division multiplexing optical transmission system that divides and transmits a tributary signal having a high speed and a large capacity compared to the optical transmission signal speed transmitted from the transmission side device to the reception side device into the optical transmission signals of a plurality of wavelengths,
The transmitting device is:
A demultiplexing circuit for demultiplexing the tributary signal;
A plurality of transmission frame generating circuits for assembling a plurality of transmission frames for a plurality of demultiplexed signals demultiplexed by the demultiplexing circuit;
An electro-optical conversion circuit that converts the plurality of transmission frames into optical signals having different wavelengths, and
With
The receiving side device
A plurality of photoelectric conversion circuits for converting optical signals having different wavelengths input via the optical transmission path into a plurality of electrical signals corresponding to the respective wavelengths;
A plurality of transmission frame termination circuits that perform reception processing of each transmission frame corresponding to each electrical signal converted by each photoelectric conversion circuit and output a demultiplexed signal that corrects a delay difference between each transmission frame, and
A multiplexing circuit that multiplexes a plurality of demultiplexed signals output from the plurality of transmission frame termination circuits and outputs the tributary signal;
With
The transmission frame generation circuit includes a delay absorption memory that absorbs a transmission delay difference between wavelengths,
Detecting means for detecting a delay difference between each wavelength in the receiving side device;
Adjustment control means for adjusting the delay amount of each wavelength by the delay absorption memory and correcting the delay difference based on the delay difference detected by the detection means;
An inverse wavelength division multiplexing optical transmission system. The transmission-side apparatus assigns each transmission frame group generated corresponding to each tributary signal of a plurality of input tributary signals to a wavelength in an adjacent wavelength group and transmits the transmission frame group. 5. The inverse wavelength division multiplexing optical transmission system according to claim 5.

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