JP7241992B2 - Multi-carrier optical transmission/reception system - Google Patents

Description

The present disclosure relates to a multi-carrier optical transmission/reception system.

An optical transmission system transmits and receives a plurality of signals for the purpose of increasing the capacity of optically transmitted information. However, the signal quality of a plurality of signals transmitted and received by the optical transmission system may be degraded due to crosstalk between the signals. Therefore, the optical transmission system performs equalization processing on the received signal.

For example, Patent Literature 1 describes a technology of a spatial multiplexing optical transmission system using a multi-core optical fiber. In the spatial multiplexing optical transmission system, by using a plurality of cores for one optical fiber, the frequency utilization efficiency can be improved, but the signal quality is degraded due to crosstalk between the cores. Therefore, the utilization of MIMO (Multi-input Multi-output) equalization signal processing technology is required to realize high-quality spatial multiplexing optical transmission. However, in the spatial multiplexing optical transmission system using the MIMO equalization signal processing technique, there is a group velocity delay of signals between spatial channels, which accumulates according to the transmission distance of the signals. Since the temporal spread of crosstalk between spatial channels spreads according to the amount of delay, the number of filter taps required for performing MIMO equalization signal processing increases according to the amount of signal delay. Therefore, there is a problem that the amount of computation for signal processing increases according to the delay difference between signals. In the spatial multiplexing optical transmission system of Patent Document 1, in the transmitter or receiver, the baud rate of each subcarrier of a multicarrier signal is set so that the amount of calculation for signal processing is within the amount of calculation that can be processed. Equalization coefficients are calculated by transmitting/receiving a known signal with a long period, and a time domain equalization processing method based on the calculated equalization coefficients reduces the amount of calculation for signal processing.

JP 2016-134840 A

In a multi-carrier transmission system in which a plurality of sub-carrier signals each having a different frequency are transmitted and received, for example, the wavelengths of the plurality of sub-carrier signals are different, causing a delay difference between the sub-carrier signals. Further, in the multicarrier transmission system, for example, the transmission path through which subcarrier signals are transmitted may change from a predetermined transmission path, and in such a case also, a delay difference occurs between subcarrier signals. If a delay difference occurs between subcarrier signals due to such a cause, there is a problem that the amount of computation for signal processing further increases. Therefore, in some cases, it is not possible to deal with the problem only by a method of reducing the amount of computation for signal processing in a transmitter or a receiver, as in the invention described in Patent Document 1 above.
The present disclosure has been made to solve the above problems, and provides a technique for reducing the amount of computation for signal processing caused by the delay difference between subcarrier signals by a method different from the conventional method. intended to

A multicarrier optical transmission/reception system according to the present disclosure is a multicarrier optical transmitter that transmits a plurality of subcarrier signals, and a transmission path that switches between transmission paths that transmit a plurality of subcarrier signals transmitted by the multicarrier optical transmitter. A switching device, a multi-carrier optical receiver that receives a plurality of subcarrier signals transmitted via transmission lines each switched by the transmission line switching device, and a subcarrier signal transmitted via the transmission line. A plurality of subcarrier signals are transmitted based on a delay amount database indicating delay amounts of subcarrier signals associated with combinations of wavelengths of subcarrier signals and transmission paths. and a transmission path determination device that determines a transmission path, and the transmission path switching device switches transmission paths through which the plurality of subcarrier signals are respectively transmitted to the transmission paths determined by the transmission path determination device.

According to the present disclosure, it is possible to reduce the computational complexity of signal processing caused by the delay difference between subcarrier signals by a method different from the conventional method.

1 is a block diagram showing the configuration of a multicarrier optical transmission/reception system according to Embodiment 1; FIG. 1 is a block diagram showing the configuration of a multicarrier optical transmitter according to Embodiment 1; FIG. 1 is a block diagram showing the configuration of a multicarrier optical receiver according to Embodiment 1; FIG. 5 is a table showing a specific example of a delay amount database according to Embodiment 1; 4 is a flow chart showing a method of constructing a delay amount database by the multi-carrier optical transmission/reception system according to Embodiment 1; 4 is a flow chart showing a communication path construction method by the multi-carrier optical transmission/reception system according to Embodiment 1; 2 is a block diagram showing the configuration of a multicarrier optical transmission/reception system according to Embodiment 2; FIG. FIG. 11 is a table showing a specific example of a delay amount database according to Embodiment 2; FIG. FIG. 9A is a block diagram showing a hardware configuration that implements the function of the reception-side signal processing unit or the function of the integrated management device of the multicarrier optical receiver according to the first or second embodiment. 9B is a block diagram showing a hardware configuration for executing software that realizes the function of the reception-side signal processing unit of the multicarrier optical receiver according to Embodiment 1 or Embodiment 2 or the function of the integrated management device; FIG. be.

Hereinafter, in order to describe the present disclosure in more detail, embodiments for carrying out the present disclosure will be described with reference to the accompanying drawings.
Embodiment 1.
FIG. 1 is a block diagram showing the configuration of a multicarrier optical transmission/reception system 100 according to Embodiment 1. As shown in FIG. As shown in FIG. 1, the multicarrier optical transmission/reception system 100 includes a multicarrier optical transmitter 10, a wavelength multiplexing/demultiplexing path switching device 1 (transmission path switching device), a wavelength multiplexing/demultiplexing path switching device 2, a wavelength multiplexing/demultiplexing Route switching device 3, wavelength multiplexing/demultiplexing route switching device 4, wavelength multiplexing/demultiplexing route switching device 5, wavelength multiplexing/demultiplexing route switching device 6, multicarrier optical receiver 11, and integrated management device 12 (transmission path determination device) It has

FIG. 2 is a block diagram showing the configuration of the multicarrier optical transmitter 10. As shown in FIG. As shown in FIG. 2, the multi-carrier optical transmitter 10 comprises a transmission-side signal generator 20 and a plurality of sub-carrier transmitters 21 .

A multicarrier optical transmitter 10 transmits a plurality of subcarrier signals. Note that the plurality of subcarrier signals here have different wavelengths λ1, λ2, . . . , λx. More specifically, in Embodiment 1, multicarrier optical transmitter 10 transmits a plurality of subcarrier signals to wavelength multiplexing/demultiplexing path switching device 1 .

More specifically, the transmission-side signal generator 20 of the multicarrier optical transmitter 10 generates carrier signals. Each of the plurality of subcarrier transmitters 21 generates a subcarrier signal by converting the frequency of the carrier signal generated by the transmission-side signal generator 20 . A plurality of subcarrier transmitters 21 respectively transmit the generated subcarrier signals to the wavelength multiplexing/demultiplexing path switching device 1 .

A wavelength multiplexing/demultiplexing path switching device 1 switches transmission paths through which a plurality of subcarrier signals transmitted by a multicarrier optical transmitter 10 are transmitted. In the example of FIG. 1, the wavelength multiplexing/demultiplexing path switching device 1 multiplexes a plurality of subcarrier signals transmitted by the multicarrier optical transmitter 10, and transmits the multiplexed signal to the transmission line A, the transmission line B, or the transmission line. Allocate to any one transmission path of C.

In Embodiment 1, a configuration in which the multicarrier optical transmission/reception system 100 includes a wavelength multiplexing/demultiplexing path switching device as a transmission line switching device will be described, but the present invention is not limited to this configuration. The transmission path switching device included in the multicarrier optical transmission/reception system 100 should be able to switch transmission paths through which a plurality of subcarrier signals transmitted by the multicarrier optical transmitter 10 are transmitted.

The wavelength multiplexing/demultiplexing path switching device 2 switches the transmission path through which the subcarrier signal transmitted by the multicarrier optical transmitter 10 and passed through the wavelength multiplexing/demultiplexing path switching device 1 and the transmission path A is transmitted. For the sake of simplification, in the example of FIG. 1, only the transmission line D is shown as the transmission line to be switched by the wavelength multiplexing/demultiplexing route switching device 2 .

The wavelength multiplexing/demultiplexing path switching device 3 switches the transmission path through which the subcarrier signal transmitted by the multicarrier optical transmitter 10 and passed through the wavelength multiplexing/demultiplexing path switching device 1 and the transmission path B is transmitted. For the sake of simplification, in the example of FIG. 1, only the transmission line E is shown as the transmission line to be switched by the wavelength multiplexing/demultiplexing switching device 3 .

The wavelength multiplexing/demultiplexing path switching device 4 switches the transmission path through which the subcarrier signal transmitted by the multicarrier optical transmitter 10 and passed through the wavelength multiplexing/demultiplexing path switching device 1 and the transmission path C is transmitted. For the sake of simplification, in the example of FIG. 1, only the transmission line F is shown as the transmission line to be switched by the wavelength multiplexing/demultiplexing switching device 4 .

The wavelength multiplexing/demultiplexing path switching device 5 transmits a subcarrier signal that has passed through the wavelength multiplexing/demultiplexing path switching device 3 and the transmission line E, or a subcarrier signal that has passed through the wavelength multiplexing/demultiplexing path switching device 4 and the transmission line F. Switch the transmission path. In the example of FIG. 1, the wavelength multiplexing/demultiplexing path switching device 5 switches between the wavelength multiplexing/demultiplexing path switching device 3 and the subcarrier signal that has passed through the transmission line E, and the wavelength multiplexing/demultiplexing path switching device 4 and the transmission line F. The subcarrier signals that have passed through are multiplexed, and the multiplexed signal is output to the transmission line G.

The wavelength multiplexing/demultiplexing path switching device 6 receives a subcarrier signal transmitted via the wavelength multiplexing/demultiplexing path switching device 2 and the transmission line D, or a subcarrier signal transmitted via the wavelength multiplexing/demultiplexing path switching device 5 and the transmission line G. Switches the transmission path through which the subcarrier signal is transmitted. In the example of FIG. 1, the wavelength multiplexing/demultiplexing path switching device 6 uses the wavelength multiplexing/demultiplexing path switching device 2 and the subcarrier signal transmitted via the transmission line D, the wavelength multiplexing/demultiplexing path switching device 5 and A subcarrier signal transmitted via the transmission line G is demultiplexed for each wavelength, and the demultiplexed signal is output to the multicarrier optical receiver 11 .

Wavelength multiplexing/demultiplexing path switching device 1, wavelength multiplexing/demultiplexing path switching device 2, wavelength multiplexing/demultiplexing path switching device 3, wavelength multiplexing/demultiplexing path switching device 4, wavelength multiplexing/demultiplexing path switching device 5, and wavelength multiplexing/demultiplexing path The switching device 6 performs the switching of the transmission line based on an instruction from the integrated management device 12, which will be described later. Details will be described later.

The transmission lines AG are individual optical fibers, such as single-core fibers or multi-core fibers. When the transmission lines AG are multi-core fibers, for example, wavelength multiplexing/demultiplexing path switching device 1, wavelength multiplexing/demultiplexing path switching device 2, wavelength multiplexing/demultiplexing path switching device 3, wavelength multiplexing/demultiplexing path switching device 4, Each of the wavelength multiplexing/demultiplexing path switching device 5 and the wavelength multiplexing/demultiplexing path switching device 6 may further have a function of switching cores through which a plurality of subcarrier signals are respectively transmitted.

For example, a subcarrier signal of wavelength λ1 emitted from the multicarrier optical transmitter 10 passes through the transmission path A, the wavelength multiplexing/demultiplexing path switching device 2 and the transmission path D in order, and reaches the wavelength multiplexing/demultiplexing path switching device 6. do. For example, a subcarrier signal of wavelength λ2 passes through transmission path B, wavelength multiplexing/demultiplexing path switching device 3, transmission path E and wavelength multiplexing/demultiplexing path switching device 5 in order, and reaches wavelength multiplexing/demultiplexing path switching device 6. do. A subcarrier signal of wavelength λx passes through transmission path C, wavelength multiplexing/demultiplexing path switching device 4 , transmission path F and wavelength multiplexing/demultiplexing path switching device 5 in order, and reaches wavelength multiplexing/demultiplexing path switching device 6 . As described above, the wavelength multiplexing/demultiplexing path switching device 1, wavelength multiplexing/demultiplexing path switching device 2, wavelength multiplexing/demultiplexing path switching device 3, wavelength multiplexing/demultiplexing path switching device 4, wavelength multiplexing/demultiplexing path switching device 5, and The wavelength multiplexing/demultiplexing path switching device 6 distributes the paths of the respective subcarrier signals, so that each subcarrier signal is finally multiplexed again by the wavelength multiplexing/demultiplexing path switching device 6, and multicarrier optical reception is performed. reaches vessel 11.

The multicarrier optical receiver 11 includes a wavelength multiplexing/demultiplexing path switching device 1, a wavelength multiplexing/demultiplexing path switching device 2, a wavelength multiplexing/demultiplexing path switching device 3, a wavelength multiplexing/demultiplexing path switching device 4, and a wavelength multiplexing/demultiplexing device. A plurality of subcarrier signals transmitted via transmission paths switched by at least one wavelength multiplexing/demultiplexing path switching device (transmission path switching device) out of the wavelength multiplexing/demultiplexing path switching device 5 or the wavelength multiplexing/demultiplexing path switching device 6. receive.

A more detailed configuration of the multicarrier optical receiver 11 will be described with reference to the drawings. FIG. 3 is a block diagram showing the configuration of the multicarrier optical receiver 11. As shown in FIG. As shown in FIG. 3, the multicarrier optical receiver 11 includes a plurality of subcarrier receivers 30 and a receiving side signal processor 31 . The receiving-side signal processing unit 31 includes a plurality of equalization processing units 32, an inter-carrier delay processing unit 33, and an error correction unit .

A plurality of subcarrier receivers 30 respectively include a wavelength multiplexing/demultiplexing path switching device 1, a wavelength multiplexing/demultiplexing path switching device 2, a wavelength multiplexing/demultiplexing path switching device 3, a wavelength multiplexing/demultiplexing path switching device 4, a wavelength multiplexing/demultiplexing receive a subcarrier signal transmitted via a transmission path switched by at least one wavelength multiplexing/demultiplexing path switching device (transmission path switching device) out of the wavelength multiplexing/demultiplexing path switching device 5 or the wavelength multiplexing/demultiplexing path switching device 6; do. The plurality of subcarrier receivers 30 each output the received subcarrier signals to corresponding equalization processing units among the plurality of equalization processing units 32 .

The plurality of equalization processors 32 of the reception-side signal processor 31 each perform equalization processing on subcarrier signals received by corresponding subcarrier receivers among the plurality of subcarrier receivers 30 . The plurality of equalization processing units 32 each output the equalized subcarrier signals to the inter-carrier delay processing unit 33 .

The inter-carrier delay processing section 33 of the reception side signal processing section 31 measures the delay amount for each subcarrier signal based on each subcarrier signal equalized by the plurality of subcarrier receivers 30 . The inter-carrier delay processing unit 33 outputs the measured delay amount for each subcarrier signal to the integrated management device 12 and the error correction unit 34, respectively.

More specifically, in Embodiment 1, the inter-carrier delay processing section 33 generates a delay difference processing failure warning based on the measured delay amount for each subcarrier signal. For example, the inter-carrier delay processing unit 33 generates a delay difference processing impossibility warning when the amount of computation for signal processing caused by the measured delay amount for each subcarrier signal exceeds the amount of computation that can be processed.
The error correction section 34 of the reception side signal processing section 31 compensates for the delay difference between subcarriers based on the amount of delay for each subcarrier signal measured by the intercarrier delay processing section 33 .

The integrated management device 12 includes a multicarrier optical transmitter 10, a multicarrier optical receiver 11, a wavelength multiplexing/demultiplexing path switching device 1, a wavelength multiplexing/demultiplexing path switching device 2, a wavelength multiplexing/demultiplexing path switching device 3, a wavelength multiplexing/demultiplexing The wavelength multiplexing/demultiplexing route switching device 4, the wavelength multiplexing/demultiplexing route switching device 5, and the wavelength multiplexing/demultiplexing route switching device 6 are centrally managed.

The integrated management device 12 stores a delay amount database. The delay amount database stores delay amounts of subcarrier signals caused by transmission of the subcarrier signals through transmission lines, which are associated with combinations of wavelengths of subcarrier signals and transmission lines. show.
The integrated management device 12 determines transmission paths through which the plurality of subcarrier signals are transmitted, based on the delay amount database.

The delay amount here may be, for example, the time itself required for the subcarrier signal to be transmitted through the target transmission line, or, for example, the subcarrier signal may be the target transmission line and the time it takes the subcarrier signal to be transmitted over a reference transmission line.

The integrated management device 12 sends information about the determined transmission line to the wavelength multiplexing/demultiplexing path switching device 1, the wavelength multiplexing/demultiplexing path switching device 2, the wavelength multiplexing/demultiplexing path switching device 3, the wavelength multiplexing/demultiplexing path switching device 4, the wavelength It is output to the multiplexing/demultiplexing path switching device 5 or the wavelength multiplexing/demultiplexing path switching device 6 .

More specifically, in Embodiment 1, the integrated management device 12 creates a delay amount database based on the delay amount for each subcarrier signal measured by the inter-carrier delay processing unit 33 . More specifically, in the first embodiment, when the multicarrier optical receiver 11 generates a delay difference processing failure alarm, the integrated management device 12 determines whether a plurality of subcarrier signals are transmitted based on the delay amount database. Change the transmission path that For example, when the multicarrier optical receiver 11 generates a delay difference processing failure alarm, the integrated management device 12 updates the delay amount database, and based on the updated delay amount database, a plurality of subcarrier signals are transmitted. You may change the transmission path to be used.

More specifically, in the first embodiment, the integrated management device 12 selects a plurality of transmission paths through which subcarrier signals are transmitted based on the delay amount database, and transmits the subcarrier signals via the selected plurality of transmission paths. is transmitted from the multicarrier optical transmitter 10 to the multicarrier optical receiver 11, the amount of signal processing caused by the delay amount of the subcarrier signal is the amount of calculation that can be processed by the multicarrier optical receiver 11. Determine whether it is within the range. When the integrated management device 12 determines that the amount of computation for signal processing caused by the delay amount is within the range of the amount of computation that can be processed by the multicarrier optical receiver 11, the integrated management device 12 divides the selected plurality of transmission paths into sub- It is determined as the route through which the carrier signal is transmitted. Instead of making the determination, the integrated management device 12 determines the delay of the subcarrier signal caused by transmission of the subcarrier signal from the multicarrier optical transmitter 10 to the multicarrier optical receiver 11 via the selected plurality of transmission paths. It may be determined whether the amount is less than or equal to a predetermined threshold. In this case, when the integrated management device 12 determines that the delay amount is equal to or less than the predetermined threshold value, the integrated management device 12 determines the selected transmission paths as the paths through which the subcarrier signals are transmitted.

In Embodiment 1, a configuration in which the multicarrier optical transmission/reception system 100 includes an integrated management device as a transmission path determination device will be described, but the configuration is not limited to this. The transmission path determination device included in the multicarrier optical transmission/reception system 100 should be able to determine transmission paths through which a plurality of subcarrier signals are transmitted, at least based on the delay amount database.

The wavelength multiplexing/demultiplexing route switching device 1, the wavelength multiplexing/demultiplexing route switching device 2, the wavelength multiplexing/demultiplexing route switching device 3, the wavelength multiplexing/demultiplexing route switching device 4, the wavelength multiplexing/demultiplexing route switching device 5, and the wavelength multiplexing/demultiplexing device described above. The wave path switching device 6 switches the transmission path through which each of the plurality of subcarrier signals is transmitted to the transmission path determined by the integrated management device 12 . Note that the configuration diagram shown in FIG. 1 is an example, and the connection configuration of each transmission line and each wavelength multiplexing/demultiplexing switching device in the multicarrier optical transmission/reception system 100 may be any connection configuration such as a ring shape or a mesh shape. can also be taken.

The delay amount database used by the integrated management device 12 will be described in more detail below. FIG. 4 is a table showing a specific example of the delay amount database. FIG. 5 is a flowchart showing a method of constructing a delay amount database by the multicarrier optical transmission/reception system 100. As shown in FIG. Note that the examples of FIGS. 4 and 5 are examples in which the transmission line is a single-core fiber.

As shown in FIG. 4, the delay amount database stores the delay amount of the subcarrier signal caused by the transmission of the subcarrier signal of wavelength λx through the transmission line y as a combination of the wavelength of the subcarrier signal and the transmission line. shown for each

As shown in FIG. 5, the integrated management device 12 sends one or more subcarrier signals to all transmission paths in the multicarrier optical transmission/reception system 100 after the transmission paths and the wavelength multiplexing/demultiplexing path switching devices are connected. are input (step ST1). The integrated management device 12 stores information about the set transmission paths as the wavelength multiplexing/demultiplexing path switching device 1, the wavelength multiplexing/demultiplexing path switching device 2, the wavelength multiplexing/demultiplexing path switching device 3, the wavelength multiplexing/demultiplexing path switching device 4, the wavelength They are output to the multiplexing/demultiplexing path switching device 5 and the wavelength multiplexing/demultiplexing path switching device 6, respectively.

Wavelength multiplexing/demultiplexing path switching device 1, wavelength multiplexing/demultiplexing path switching device 2, wavelength multiplexing/demultiplexing path switching device 3, wavelength multiplexing/demultiplexing path switching device 4, wavelength multiplexing/demultiplexing path switching device 5, and wavelength multiplexing/demultiplexing path The switching device 6 switches the transmission paths through which the plurality of subcarrier signals are respectively transmitted to the transmission paths set by the integrated management device 12 in step ST1.

A multi-carrier optical transmitter 10 transmits a plurality of sub-carrier signals for delay amount measurement, and a multi-carrier optical receiver 11 receives a plurality of sub-carrier signals each transmitted via a transmission line.

The inter-carrier delay processing unit 33 of the reception-side signal processing unit 31 of the multicarrier optical receiver 11 measures the delay amount for each subcarrier signal based on the received plurality of subcarrier signals, and the integrated management device 12 The delay amount for each subcarrier signal is collected from the multicarrier optical receiver 11, and the delay amount database shown in FIG. 4 is constructed based on the delay amount for each subcarrier signal and the transmission path set in step ST1. (step ST2).

The procedure of the delay amount database construction method described above shows the procedure when the transmission line is a single-core fiber. However, a similar procedure can be used even if the transmission line is a multi-core fiber. For example, the amount of delay of a subcarrier signal transmitted by a multi-core fiber is almost the same even when the sub-carrier signal is transmitted through different cores in the multi-core fiber. The device 12 only needs to have a delay amount database regarding the path of any one of the multiple cores in the multi-core fiber.

A method of constructing a communication path by the multicarrier optical transmission/reception system 100 will be described below. FIG. 6 is a flow chart showing a communication path construction method by the multi-carrier optical transmission/reception system 100. As shown in FIG.

As shown in FIG. 6, the integrated management device 12 connects the start and end points of the communication path from the multicarrier optical transmitter 10 to the multicarrier optical receiver 11 and ensures the continuity of the wavelengths of the subcarrier signals. is searched (step ST10). It should be noted that the route here is composed of a plurality of transmission lines.

The integrated management device 12 selects the reference route with the smallest delay amount as the route of the first subcarrier signal from among the unused routes among the searched routes based on the delay amount database (step ST11 ).
Integrated management device 12 selects a path with a delay amount close to the delay amount of the reference path as the path for the second subcarrier signal other than the first subcarrier signal (step ST12).

The integrated management device 12 determines whether or not the amount of computation for signal processing caused by the delay amount of the path selected in step ST12 is within the range of the amount of computation that can be processed by the multicarrier optical receiver 11 (step ST13).

When the integrated management device 12 determines that the amount of computation for signal processing caused by the delay amount of the path selected in step ST12 is within the range of the amount of computation that can be processed by the multicarrier optical receiver 11 (in step ST13 YES), the selected path is determined as the path through which the second subcarrier signal is transmitted, and the determined path is sent to the wavelength multiplexing/demultiplexing path switching device 1, the wavelength multiplexing/demultiplexing path switching device 2, the wavelength multiplexing/demultiplexing Notifies at least one of the wavelength multiplexing/demultiplexing route switching device 3, the wavelength multiplexing/demultiplexing route switching device 4, the wavelength multiplexing/demultiplexing route switching device 5, or the wavelength multiplexing/demultiplexing route switching device 6 (step ST14 ).

When the integrated management device 12 determines that the amount of computation for signal processing caused by the delay amount of the path selected in step ST12 is within the range of the amount of computation that can be processed by the multicarrier optical receiver 11 (in step ST13 NO), the process returns to step ST10.

After step ST14 described above, wavelength multiplexing/demultiplexing route switching device 1, wavelength multiplexing/demultiplexing route switching device 2, wavelength multiplexing/demultiplexing route switching device 3, wavelength multiplexing/demultiplexing route switching device 4, wavelength multiplexing/demultiplexing route switching device 5 or the wavelength multiplexing/demultiplexing path switching device 6 selects the transmission line through which the second subcarrier signal is transmitted according to the transmission path determined by the integrated management device 12 in step ST14. switch to road.

A multicarrier optical transmitter 10 transmits a plurality of subcarrier signals including a second subcarrier signal, and a multicarrier optical receiver 11 receives a plurality of subcarrier signals each transmitted via a transmission line. do. The inter-carrier delay processing unit 33 of the reception-side signal processing unit 31 in the multicarrier optical receiver 11 measures the amount of delay for each subcarrier signal, and calculates the amount of signal processing due to the measured amount of delay for each subcarrier signal. exceeds the amount of computation that can be processed, a delay difference processing inability alarm is generated. Also, in that case, the inter-carrier delay processing unit 33 outputs the measured delay amount for each subcarrier signal to the integrated management device 12 .
Next, the integrated management device 12 determines whether or not a delay difference processing impossibility warning has been received from the inter-carrier delay processing unit 33 (step ST15).

When the integrated management device 12 determines that it has received the delay difference processing impossibility warning from the inter-carrier delay processing unit 33 (YES in step ST15), it returns to the processing of step ST10, and the delay difference processing impossibility from the inter-carrier delay processing unit 33. If it is determined that no warning has been received (NO in step ST15), the process is terminated.

For example, if a fiber is added due to a problem in the transmission line after the delay amount database is constructed, the delay amount may deviate from the database. Therefore, even when a path is established and communication is started, the inter-carrier delay processing unit 33 of the multicarrier optical receiver 11 generates a delay difference processing failure alarm, and the integrated management device 12 performs the delay difference processing. A procedure for receiving a disabled alarm is required.

Although not shown, for example, when the integrated management device 12 receives a delay difference processing impossibility warning (YES in step ST15), before the processing in step ST10, the inter-carrier delay processing unit 33 measures Based on the delay amount, among the paths of the plurality of subcarrier signals, a path whose measured delay amount significantly deviates from the delay amount indicated by the delay amount database is determined. The integrated management device 12 updates the delay amount database by the same method as the delay amount database constructing method described with reference to FIG. 5, based on the determined route. By constructing a communication path according to such a procedure, it is possible to construct a path with a smaller delay difference between subcarrier signals and a smaller absolute value of the delay amount than in the conventional case. If the transmission path is multi-core fiber, it is possible to construct a path with almost no delay difference between sub-carrier signals by using different cores in the same path and aligning the wavelength of each sub-carrier in the multi-core fiber. Therefore, the processing time can be reduced.

As described above, by managing the amount of communication delay in the entire system, it is possible to select the path and the wavelength of the subcarrier signal that minimize the delay difference between subcarrier signals, and reduce the computational complexity of signal processing caused by the delay difference. It is also possible to reduce In addition to suppressing the delay difference that occurs between subcarrier signals, it is also possible to search for paths with relatively short delay times. , it becomes possible to establish a route for communication with a reduced delay difference.

As described above, the multicarrier optical transmission/reception system 100 according to Embodiment 1 includes the multicarrier optical transmitter 10 that transmits a plurality of subcarrier signals, and the plurality of subcarrier signals transmitted by the multicarrier optical transmitter 10. A wavelength multiplexing/demultiplexing path switching device 1 (transmission path switching device) that switches transmission paths for transmission, and a plurality of subcarriers transmitted via the transmission paths switched by the wavelength multiplexing/demultiplexing path switching device 1. The amount of delay of the subcarrier signal caused by the multicarrier optical receiver 11 receiving the signal and the transmission of the subcarrier signal via the transmission line, for each combination of the wavelength of the subcarrier signal and the transmission line an integrated management device 12 (transmission path determination device) that determines transmission paths through which a plurality of subcarrier signals are respectively transmitted, based on a delay amount database that indicates associated delay amounts; The switching device 1 switches the transmission paths through which the plurality of subcarrier signals are respectively transmitted to the transmission paths determined by the integrated management device 12 .

According to the above configuration, even if a delay difference occurs between the subcarrier signals due to, for example, a change in the wavelength of the subcarrier signal or the transmission path, the wavelength of the subcarrier signal and the transmission path The delay difference between subcarrier signals can be reduced by switching the transmission path through which the subcarrier signals are transmitted based on the delay amount database indicating the delay amount associated with each combination of . Therefore, it is possible to reduce the computational complexity of signal processing caused by the delay difference between subcarrier signals.

For example, when the length of a signal transmission path is several hundred kilometers, a delay difference of about 100 ns occurs between signals. It reduced the amount of processing caused. However, in actual metro systems, it is possible that each subcarrier signal of a multicarrier does not pass through a predetermined route, so it is conceivable that a delay difference of 100 ns or more, which cannot be processed by the conventional technology, may occur. Furthermore, with the introduction of an OXC (Optical Cross Connect) system that switches the signal path when a path failure occurs, it is necessary to change the compensation value for the delay difference between subcarrier signals each time a path failure occurs. However, these problems cannot be dealt with by simply compensating for the delay difference by signal processing performed by the transceiver alone, as in the prior art.

However, according to the above-described configuration of the multicarrier optical transmission/reception system 100 according to Embodiment 1, the delay difference caused by the difference in wavelength between subcarrier signals in the entire system, the transmission path and path through which the subcarrier signals are transmitted, It is possible to manage the delay difference that occurs due to the difference in By managing the system as a whole, when multi-core fiber is introduced as a transmission line, it is possible to put light into different cores on the same route. It is also possible to reduce the computational complexity of signal processing due to the delay difference between the two.

The multicarrier optical receiver 11 in the multicarrier optical transmission/reception system 100 according to the first embodiment measures the delay amount for each subcarrier signal based on a plurality of received subcarrier signals, and the integrated management device 12 (transmission path determination device) creates a delay amount database based on the delay amount for each subcarrier signal measured by the multicarrier optical receiver 11 .

According to the above configuration, a delay amount database can be created based on the measured delay amounts. Then, by switching the transmission path through which the subcarrier signals are transmitted based on the created delay amount database, it is possible to reduce the delay difference between the subcarrier signals. Therefore, it is possible to reduce the computational complexity of signal processing caused by the delay difference between subcarrier signals.

For example, when a plurality of subcarrier signals are received by different receivers and the delay amount is measured for each receiver, an error occurs in the delay difference measurement. However, as in the configuration of the multicarrier optical transmission/reception system 100 according to Embodiment 1, by measuring the delay amount with the reception side signal processing section 31 in the multicarrier optical receiver 11, the reception side signal processing section 31 alone , the delay amount measurement error can be reduced, and the delay amount database can be created favorably.

The multicarrier optical receiver 11 in the multicarrier optical transmission/reception system 100 according to Embodiment 1 measures the delay amount for each subcarrier signal based on a plurality of received subcarrier signals, and calculates the delay amount for each measured subcarrier signal. Based on the delay amount, a delay difference processing impossibility alarm is generated, and when the multicarrier optical receiver 11 generates the delay difference processing impossibility alarm, the integrated management device 12 (transmission path determination device) generates a delay difference processing impossibility alarm based on the delay amount database. , change the transmission path through which each of the plurality of subcarrier signals is transmitted.

According to the above configuration, for example, when the amount of computation for signal processing due to the delay difference between subcarrier signals exceeds the amount of computation that can be processed, the subcarrier signal is transmitted based on the delay difference processing impossibility warning. It is possible to change the transmission path to be used. Therefore, the delay difference between subcarrier signals can be reduced. Therefore, it is possible to reduce the computational complexity of signal processing caused by the delay difference between subcarrier signals.

The integrated management device 12 (transmission path determination device) in the multicarrier optical transmission/reception system 100 according to the first embodiment selects a plurality of transmission paths through which subcarrier signals are transmitted based on the delay amount database, and selects a plurality of selected transmission paths. The amount of calculation of signal processing caused by the amount of delay of the subcarrier signal caused by the transmission of the subcarrier signal from the multicarrier optical transmitter 10 to the multicarrier optical receiver 11 via the transmission path is the multicarrier optical receiver. 11, and determines whether or not the amount of computation for signal processing caused by the delay amount is within the range of the amount of computation that can be processed by the multicarrier optical receiver 11. If determined, the selected transmission paths are determined as paths through which subcarrier signals are transmitted.

According to the above configuration, by switching each transmission path so that the subcarrier signal is transmitted from the multicarrier optical transmitter 10 to the multicarrier optical receiver 11 via the determined path, Delay difference can be reduced. Therefore, it is possible to reduce the computational complexity of signal processing caused by the delay difference between subcarrier signals.

Embodiment 2.
In the first embodiment, an example in which the transmission line in the multi-carrier optical transmission/reception system 100 is configured by a single-core optical fiber or a multi-core fiber has been described. An example configured by a mode optical fiber will be described.

Embodiment 2 will be described below with reference to the drawings. In addition, the same reference numerals are given to the configurations having the same functions as the configurations described in the first embodiment, and the description thereof will be omitted.
FIG. 7 is a block diagram showing the configuration of multicarrier optical transmission/reception system 101 according to the second embodiment. As shown in FIG. 7, the multicarrier optical transmission/reception system 101 is different from the multicarrier optical transmission/reception system 100 according to Embodiment 1 in that instead of the wavelength multiplexing/demultiplexing path switching device 1, a mode-coupled wavelength multiplexing/demultiplexing system is used. A path switching device 40 is provided, and instead of the wavelength multiplexing/demultiplexing path switching device 6, a mode-coupled wavelength multiplexing/demultiplexing path switching device 41 is provided.
A transmission line in the multicarrier optical transmission/reception system 101 is a multimode optical fiber or a multicore multimode optical fiber.

In addition to the functions of the wavelength multiplexing/demultiplexing path switching apparatus 1 described in the first embodiment, the mode-coupled wavelength multiplexing/demultiplexing path switching apparatus 40 is configured to It further has a function to convert . As a result, the subcarrier signals propagated through the transmission lines AG are propagated in the post-conversion mode.

The mode-coupled wavelength multiplexing/demultiplexing path switching device 41 has the function of the wavelength multiplexing/demultiplexing path switching device 6 described in the first embodiment. It further has a function of combining the mode of the subcarrier signal transmitted via the wavelength multiplexing/demultiplexing path switching device 5 and the transmission line G. FIG.

The integrated management device 12 (transmission path determination device) according to the second embodiment is based on a delay amount database indicating the delay amount associated with each combination of the wavelength of the subcarrier signal, the mode of the subcarrier signal, and the transmission path. to determine the transmission path through which each of the plurality of subcarrier signals is transmitted.

FIG. 8 is a table showing a specific example of the delay amount database according to the second embodiment. As shown in FIG. 8, the delay amount database stores the delay amount of a subcarrier signal caused by transmission of a subcarrier signal whose mode is mode z and whose wavelength is wavelength λx through transmission line y. Each combination of the wavelength of the carrier signal, the mode of the subcarrier signal, and the transmission path is shown.

The delay amount database construction method by the multi-carrier optical transmission/reception system 101 is the same as the delay amount database construction method according to Embodiment 1, except that the mode of the subcarrier signal is associated when constructing the delay amount database. . Further, the communication path construction method by the multi-carrier optical transmission/reception system 101 is the communication path construction method according to Embodiment 1, except that the delay amount database further associated with the mode of the subcarrier signal is used as the delay amount database. is similar to

As an index specific to multimode fibers that propagate subcarrier signals in multiple modes, there is also the group velocity delay difference between modes. In multi-carrier communication as well, it is possible to reduce the amount of computation for signal processing due to delay differences. In addition, by using a delay amount database that further considers the mode of subcarrier signals as factors that cause delay amounts, it becomes possible to select a more optimal path that reduces the delay difference between subcarriers.

As described above, the transmission path in the multicarrier optical transmission/reception system 101 according to Embodiment 2 is a multimode optical fiber or a multicore multimode optical fiber, and the integrated management device 12 (transmission path determination device) uses subcarrier signals A transmission path through which each of the plurality of subcarrier signals is transmitted is determined based on a delay amount database that indicates the delay amount associated with each combination of the wavelength of the subcarrier, the mode of the subcarrier signal, and the transmission path.

According to the above configuration, for example, even if a delay difference occurs between the modes due to the difference in the mode of the subcarrier signal, the wavelength of the subcarrier signal, the mode of the subcarrier signal, and the transmission path By switching the transmission path through which the subcarrier signal is transmitted based on the delay amount database indicating the delay amount associated with each combination of , the delay difference between modes can be reduced.

The functions of the equalization processor 32, the inter-carrier delay processor 33, and the error corrector 34 in the reception-side signal processor 31 of the multicarrier optical receiver 11 and the functions of the integrated management device 12 are realized by processing circuits. That is, the multicarrier optical receiver 11 and the integrated management device 12 have processing circuits for executing the processing of each step shown in FIGS. This processing circuit may be dedicated hardware, or may be a CPU (Central Processing Unit) that executes a program stored in a memory.

FIG. 9A is a block diagram showing a hardware configuration that implements the functions of the reception-side signal processing unit 31 of the multicarrier optical receiver 11 or the functions of the integrated management device 12. As shown in FIG. FIG. 9B is a block diagram showing a hardware configuration for executing software that implements the functions of the reception-side signal processing unit 31 of the multicarrier optical receiver 11 or the functions of the integrated management device 12. As shown in FIG.

If the processing circuit is the dedicated hardware processing circuit 50 shown in FIG. 9A, the processing circuit 50 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an Application Specific Integrated Integrated Circuit (ASIC), Circuit), FPGA (Field-Programmable Gate Array), or a combination thereof.

The functions of the equalization processing unit 32, the inter-carrier delay processing unit 33 and the error correction unit 34 in the reception side signal processing unit 31 of the multicarrier optical receiver 11 and the functions of the integrated management device 12 are realized by separate processing circuits. Alternatively, these functions may be collectively realized by one processing circuit.

When the processing circuit is the processor 51 shown in FIG. 7B, each function of the equalization processing unit 32, the inter-carrier delay processing unit 33, and the error correction unit 34 in the reception-side signal processing unit 31 of the multicarrier optical receiver 11, or The functions of the integrated management device 12 are implemented by software, firmware, or a combination of software and firmware.
Software or firmware is written as a program and stored in the memory 52 .

The processor 51 reads out and executes a program stored in the memory 52 to perform the equalization processing unit 32, the inter-carrier delay processing unit 33, and the error correction unit 34 in the reception-side signal processing unit 31 of the multicarrier optical receiver 11. or the functions of the integrated management device 12. That is, when the processor 51 executes these functions, the reception-side signal processing unit 31 of the multicarrier optical receiver 11 or the integrated management device 12 performs the processing of each step shown in FIGS. A memory 52 is provided for storing the resulting program to be executed.

These programs are the procedures or methods of the equalization processor 32, the inter-carrier delay processor 33, and the error corrector 34 in the reception-side signal processor 31 of the multicarrier optical receiver 11, or the functions of the integrated management device 12. Cause a computer to perform a procedure or method. The memory 52 stores a program for functioning as the equalization processing unit 32, the inter-carrier delay processing unit 33, and the error correction unit 34 in the reception side signal processing unit 31 of the multicarrier optical receiver 11, or as the integrated management device 12. computer readable storage medium.

The processor 51 corresponds to, for example, a CPU (Central Processing Unit), a processing device, an arithmetic device, a processor, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor).

The memory 52 includes, for example, non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically-EPROM), Magnetic discs such as hard discs and flexible discs, flexible discs, optical discs, compact discs, mini discs, CDs (Compact Discs), DVDs (Digital Versatile Discs), and the like.

Part of the functions of the equalization processing unit 32, the inter-carrier delay processing unit 33, and the error correction unit 34 in the reception-side signal processing unit 31 of the multicarrier optical receiver 11, or the functions of the integrated management device 12 is provided by dedicated hardware. , and may be partially implemented in software or firmware.

For example, the function of the equalization processing unit 32 is realized by a processing circuit as dedicated hardware. The functions of the inter-carrier delay processing unit 33 and the error correction unit 34 may be realized by the processor 51 reading and executing a program stored in the memory 52 .
As such, the processing circuitry may implement each of the above functions in hardware, software, firmware, or a combination thereof.
It should be noted that it is possible to freely combine each embodiment, modify any component of each embodiment, or omit any component from each embodiment.

Since the multicarrier optical transmission/reception system according to the present disclosure can reduce the amount of computation for signal processing caused by delay differences between subcarrier signals, it can be used for techniques for transmitting and receiving a plurality of subcarrier signals.

1, 2, 3, 4, 5, 6 wavelength multiplexing/demultiplexing path switching device, 10 multi-carrier optical transmitter, 11 multi-carrier optical receiver, 12 integrated management device, 20 transmission side signal generator, 21 sub-carrier transmitter , 30 subcarrier receiver, 31 receiving side signal processor, 32 equalization processor, 33 inter-carrier delay processor, 34 error corrector, 40 mode-coupled wavelength multiplexer/demultiplexer path switching device, 41 mode-coupled wavelength multiplexer/demultiplexer Path switching device 50 Processing circuit 51 Processor 52 Memory 100 Multicarrier optical transmission/reception system 101 Multicarrier optical transmission/reception system.

Claims (5)

a multi-carrier optical transmitter for transmitting multiple sub-carrier signals;
a transmission line switching device for switching transmission lines through which the plurality of subcarrier signals transmitted by the multicarrier optical transmitter are respectively transmitted;
a multicarrier optical receiver that receives a plurality of subcarrier signals each transmitted via a transmission line switched by the transmission line switching device;
a delay amount of the subcarrier signal caused by transmission of the subcarrier signal through the transmission line, the delay amount associated with each combination of the wavelength of the subcarrier signal and the transmission line; a transmission path determination device that determines a transmission path through which each of the plurality of subcarrier signals is transmitted, based on the delay amount database shown;
The multicarrier optical transmission/reception system, wherein the transmission path switching device switches transmission paths through which the plurality of subcarrier signals are respectively transmitted to the transmission paths determined by the transmission path determination device. The multicarrier optical receiver measures the delay amount for each of the subcarrier signals based on a plurality of received subcarrier signals,
2. The multicarrier optical transmission/reception according to claim 1, wherein said transmission path determination device creates said delay amount database based on the delay amount for each subcarrier signal measured by said multicarrier optical receiver. system. The multicarrier optical receiver measures the delay amount for each subcarrier signal based on a plurality of received subcarrier signals, and issues a delay difference processing failure alarm based on the measured delay amount for each subcarrier signal. to generate
When the multicarrier optical receiver generates the delay difference processing failure warning, the transmission path determination device changes transmission paths through which the plurality of subcarrier signals are transmitted, based on the delay amount database. The multi-carrier optical transmission/reception system according to claim 1, characterized by: The transmission path determination device,
selecting a plurality of transmission paths through which the subcarrier signals are transmitted based on the delay amount database;
Amount of computation for signal processing caused by a delay amount of the subcarrier signal caused by transmission of the subcarrier signal from the multicarrier optical transmitter to the multicarrier optical receiver via a plurality of selected transmission paths. is within the range of the amount of computation that can be processed by the multicarrier optical receiver,
When it is determined that the amount of computation for signal processing caused by the delay amount is within the range of the amount of computation that can be processed by the multicarrier optical receiver, the subcarrier signals are transmitted through the selected plurality of transmission paths. 2. The multi-carrier optical transmission/reception system according to claim 1, wherein the route is determined as a route that the transmission line is a multimode optical fiber or a multicore multimode optical fiber;
The transmission path determination device determines the plurality of subcarrier signals based on a delay amount database indicating delay amounts associated with each combination of the wavelength of the subcarrier signal, the mode of the subcarrier signal, and the transmission path. 2. The multi-carrier optical transmission/reception system according to claim 1, wherein the transmission paths through which are respectively transmitted are determined.

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