JP6484935B2 - Multi-carrier optical transmission system, optical receiver, and multi-carrier optical transmission method - Google Patents

Description

  The present invention relates to a multicarrier optical transmission system, an optical receiver, and a multicarrier optical transmission method, and more particularly to a multicarrier optical transmission system, an optical receiver, and a multicarrier optical transmission method used in a backbone optical network.

  Due to the explosive spread of the Internet, there is a demand for an increase in capacity of the backbone optical network. Therefore, an optical transmission network using a wavelength division multiplexing (WDM) technique capable of transmitting a large volume of traffic and a digital coherent technique for correcting a signal distortion by digital signal processing has been developed.

  In recent years, due to the diversification of services provided by networks and the spread of multi-function terminals, there is a need for technology for transmitting even larger volumes of traffic. For example, video content services represented by video streaming services are rapidly increasing. Service data that requires a larger transmission capacity than the conventional image service has become a large proportion of Internet traffic. In order to cope with the rapid expansion of the transmission capacity in the network due to this, there is a demand for a technique for maximizing the utilization efficiency of existing transmission facilities in parallel with the addition of transmission facilities and apparatuses. As a technique for maximizing the utilization efficiency of existing transmission facilities, research and development of an elastic optical network capable of significantly improving the frequency utilization efficiency in an optical fiber is being carried out.

  An elastic optical network is an optical network that selects and communicates with an optimal modulation scheme according to transmission distance and required throughput. Since an optimum modulation method can be selected, it is possible to transmit in a minimum frequency band in an elastic optical network. This is expected to greatly improve the frequency utilization efficiency. Furthermore, the frequency interval between channels can be greatly reduced by introducing frequency slots with finer granularity in place of a fixed grid such as 50 GHz or 100 GHz that has been used conventionally.

  For an optical transceiver used in an elastic optical network capable of transmitting such a large amount of data with high efficiency, a client signal to be accommodated by selecting an optimum modulation method according to the transmission distance and the required throughput. The function to transmit is required. However, since the throughput required for these optical transceivers exceeds the pace of improving the performance of electronic circuits, there is a problem that it is difficult to realize. As a technique for solving such a problem, there is a technique for parallelizing transmission methods in an optical transceiver. That is, the above problem can be solved by a multi-carrier optical transmission system that transmits a single client signal in parallel on a plurality of optical carriers.

  An example of such a multi-carrier optical transmission system is described in Patent Document 1. The related optical transmission system described in Patent Document 1 receives an optical signal from the client side, converts it to a network side signal and outputs it, receives an optical signal from the network side, and sends it to the client side. It consists of a receiving block that converts and outputs a signal.

  The transmission block includes client signal receiving means, frame accommodating means, precoding means, and optical modulation means. Here, the client signal receiving means receives a client optical signal transmitted in a parallel format in the optical frequency or wavelength region, and converts it into an electrical signal without changing the number of parallel lanes of the optical signal. The frame accommodating means replaces the parallel format electric signal with the transmission frame for the network side in the parallel format. The precoding means performs code conversion on the parallel signal from the frame accommodation means as required. The optical modulation means performs optical modulation of a plurality of optical carriers using the precoded signal generated by the precoding means.

  The reception block includes subcarrier separation means, subcarrier reception means, frame processing means, and client signal transmission means. Here, the subcarrier separation means separates the optical modulation signal received from the transmission block. The subcarrier reception means receives each subcarrier signal separated by the subcarrier separation means and performs decoding. The frame processing means performs frame processing of the subcarrier signal decoded by the subcarrier receiving means, and extracts a parallelized client signal from the transmission frame for the network side. The client signal transmission means converts the parallelized client signal into a parallelized optical signal.

  In the related optical transmission system described above, the network-side transmission frame structure handled by the frame accommodation unit and the frame processing unit is an OTU (Optical channel Transport Unit) frame. Here, the OTU frame refers to an optical transport network (Optical Transport Network) standardized by the International Telecommunication Union (ITU) Telecommunication Standardization Sector (ITU-T). It is a transmission frame structure of a floor (ITU-T recommendation G.709). By adopting the transmission form of the OTU frame, it becomes possible to transmit various client signals efficiently and with high reliability over a wide area optical network.

  FIG. 8 shows an OTU frame structure standardized by ITU-T. ITU-T Recommendation G. 709 defines a frame structure of 4 rows and 4080 columns (4 × 4080 = 16320 bytes) as an OTU frame. The frame structure is composed of three parts: an overhead part (OH part), a payload part, and an error correction code part (FEC part).

  The overhead part (OH part) is composed of FAS (Frame Alignment Signal), OTU-OH, ODU-OH, and OPU-OH. The FAS is a byte that realizes frame synchronization. Further, the OTU-OH section has a byte for signal quality monitoring such as SM (Section Monitoring), and has a bit error monitoring function called BIP (Bit Interleaved Parity). Therefore, by monitoring and managing optical signals in units of OTU frames, it becomes possible to monitor signal quality that cannot be understood only by information on the optical layer such as S / N ratio, input power, and chromatic dispersion. Note that client data is accommodated in the payload portion.

  When this OTU frame is applied to a multi-channel parallel interface, a method of distributing the round-robin to each of a plurality of physical / logical lanes every 16 bytes is described in ITU-T Recommendation G. 709 (ITU-T recommendation G.709, Annex C). By dividing and multiplexing the OTU frame in this way, a single OTU frame can be mapped to a plurality of optical carriers.

JP 2010-050803 A

In the above-described elastic optical network, ITU-T Recommendation G. Since the flexible frequency grid standardized in 694.1 is introduced, the number of optical carriers increases. For example, when a flexible frequency grid having a minimum frequency interval of 6.25 GHz is used as an optical carrier, there are a large number of optical carriers in a frequency band obtained by adding up a C band (Conventional band) and an L band (Long Wavelength band). Become. In order to monitor and manage the signal quality of these optical carriers, it is necessary to monitor the optical signal in units of OTU frames as described above.
However, when the method shown in the background art is used, it is necessary to reconstruct an OTU frame from 16-byte blocks mapped to all optical carriers on the receiving side, and extract and analyze signal quality information from the OTU frame. Therefore, the number of processes for monitoring the signal quality and the number of monitor information management are increased, and there is a problem that the real-time property at the time of abnormality detection is impaired.

  As described above, when the flexible frequency grid is introduced into the multicarrier optical transmission system, there is a problem that the number of processes for monitoring the signal quality of the optical carrier increases.

  The object of the present invention is to solve the above-mentioned problem, that is, the introduction of a flexible frequency grid in a multi-carrier optical transmission system increases the number of processes for monitoring the signal quality of the optical carrier. A system, an optical receiver, and a multicarrier optical transmission method are provided.

  The multicarrier optical transmission system of the present invention accommodates a client signal in an optical transmission frame, and a plurality of optical subcarriers in which unit optical transmission frames, which are one unit of the optical transmission frame, are continuously arranged on the frequency axis An optical transmitter for transmitting by a predetermined optical subcarrier, and receiving a plurality of optical subcarriers, reconfiguring a unit optical transmission frame from the predetermined optical subcarrier, and monitoring the signal quality by the unit optical transmission frame And an optical receiver.

  The optical receiver of the present invention receives a plurality of optical subcarriers including a predetermined optical subcarrier in which a unit optical transmission frame that is a unit of the optical transmission frame is accommodated, and transmits the unit optical transmission frame from the predetermined optical subcarrier. The signal quality is monitored by the unit optical transmission frame.

  In the multicarrier optical transmission method of the present invention, a client signal is accommodated in an optical transmission frame, and a plurality of optical subcarriers in which unit optical transmission frames, which are one unit of the optical transmission frame, are continuously arranged on the frequency axis. Are transmitted by a predetermined optical subcarrier, a plurality of optical subcarriers are received, a unit optical transmission frame is reconstructed from the predetermined optical subcarrier, and signal quality is monitored by the unit optical transmission frame.

  According to the multicarrier optical transmission system, optical receiver, and multicarrier optical transmission method of the present invention, even when a flexible frequency grid is introduced into the multicarrier optical transmission system, the signal quality of the optical carrier is monitored. An increase in the number of processes can be suppressed.

It is a block diagram which shows the structure of the multicarrier optical transmission system which concerns on the 1st Embodiment of this invention. It is the block diagram which shows the structure of the optical transmitter which concerns on the 2nd Embodiment of this invention, and the schematic diagram of an optical output. It is the block diagram which shows the structure of the optical transmission module with which the optical transmitter which concerns on the 2nd Embodiment of this invention is provided, and the schematic diagram of optical output. It is a figure for demonstrating operation | movement of the optical transmitter which concerns on the 2nd Embodiment of this invention. It is the block diagram which shows the structure of the optical transmitter which concerns on the 3rd Embodiment of this invention, and the schematic diagram of an optical output. It is the block diagram which shows the structure of the optical transmission module with which the optical transmitter which concerns on the 3rd Embodiment of this invention is provided, and the schematic diagram of optical output. It is a figure for demonstrating operation | movement of the optical transmitter which concerns on the 3rd Embodiment of this invention. It is the block diagram which shows the structure of the optical transmitter which concerns on the 4th Embodiment of this invention, and the schematic diagram of an optical output. It is a figure for demonstrating operation | movement of the optical transmitter which concerns on the 4th Embodiment of this invention. It is a figure which shows the frame structure of OTU standardized by ITU-T.

  Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing a configuration of a multicarrier optical transmission system 100 according to the first embodiment of the present invention. The multicarrier optical transmission system 100 includes an optical transmitter 110 and an optical receiver 120.

  The optical transmitter 110 accommodates a client signal in an optical transmission frame, and a predetermined number of optical subcarriers among a plurality of optical subcarriers in which unit optical transmission frames, which are one unit of the optical transmission frame, are continuously arranged on the frequency axis. Are transmitted by optical subcarriers. The optical receiver 120 receives a plurality of optical subcarriers, reconfigures a unit optical transmission frame from predetermined optical subcarriers, and monitors signal quality using the unit optical transmission frame. Here, the optical transmission frame described above is typically ITU-T recommendation G.264. This is an OTU (Optical Channel Transport Unit) frame standardized in 709.

  As shown in FIG. 1, the optical transmitter 110 can be configured to include a client signal reception unit 111, an optical transmission frame storage unit 112, and an optical modulation unit 113. Here, the client signal receiving unit 111 receives a client signal. The optical transmission frame storage unit 112 stores the client signal in the optical transmission frame. Then, the optical modulation unit 113 transmits a multicarrier optical signal including a unit frame optical signal obtained by modulating a predetermined optical subcarrier using a unit optical transmission frame that is a unit of the optical transmission frame.

  In addition, the optical receiver 120 can be configured to include a multicarrier optical signal receiver 121, an optical transmission frame regenerator 122, a monitor 123, and a client signal transmitter 124. Here, the multicarrier optical signal receiving unit 121 receives the multicarrier optical signal and demodulates the unit frame optical signal. The optical transmission frame reproducing unit 122 reconstructs a unit optical transmission frame from the demodulated unit frame optical signal. The monitor unit 123 monitors the signal quality using the unit optical transmission frame. Then, the client signal sending unit 124 extracts and sends a client signal from the optical transmission frame including the unit optical transmission frame.

  In the multicarrier optical transmission method according to the present embodiment, the client signal is first accommodated in the optical transmission frame. Then, a unit optical transmission frame, which is a unit of the optical transmission frame, is transmitted by a predetermined optical subcarrier among a plurality of optical subcarriers arranged continuously on the frequency axis. Thereafter, the plurality of optical subcarriers at this time are received, and a unit optical transmission frame is reconstructed from the predetermined optical subcarriers. The signal quality is monitored by the unit optical transmission frame.

  As described above, in the multicarrier optical transmission system 100 and the multicarrier optical transmission method of the present embodiment, the unit optical transmission frame is transmitted by a predetermined optical subcarrier, and the signal quality is monitored by the unit optical transmission frame. Yes. Therefore, it is possible to monitor the quality of the transmission signal by extracting and analyzing the monitor information from only the unit optical transmission frame, so that the number of processes for monitoring can be reduced. That is, according to the multicarrier optical transmission system and the multicarrier optical transmission method of the present embodiment, even when a flexible frequency grid is introduced into the multicarrier optical transmission system, the process for monitoring the signal quality of the optical carrier An increase in the number can be suppressed.

  The effect of the multicarrier optical transmission system 100 of this embodiment will be described more specifically.

  A case where six optical subcarriers are arranged as a plurality of optical subcarriers arranged continuously on the frequency axis will be described as an example. An OTU frame as an optical transmission frame is allocated to each of the six optical subcarriers. Here, it is assumed that the predetermined optical subcarrier is a single optical subcarrier among a plurality of optical subcarriers. That is, it is assumed that data mapping is performed on a one-to-one basis between subcarrier throughput and OTU frame throughput.

  At this time, in the method described in the background art, it is necessary to extract the monitor information in all the OTU frames of the six optical subcarriers and analyze the transmission quality. On the other hand, in the multicarrier optical transmission system of this embodiment, only the monitor information of the OTU frame mapped to a single optical subcarrier needs to be extracted and analyzed. Therefore, in this example, the number of processes for monitoring signal quality can be reduced to 1/6.

  In the above description, the throughput of the optical subcarrier and the throughput of the OTU frame correspond one-to-one, and only the OTU frame mapped to a single (one) optical subcarrier is analyzed. However, the present invention is not limited to this, and the predetermined optical subcarrier may be two or more optical subcarriers among the plurality of optical subcarriers. In this case, the optical transmitter divides the unit optical transmission frame, and transmits the divided unit optical transmission frame by two or more optical subcarriers. For example, when the throughput of the OTU frame and the throughput of the optical subcarrier correspond to each other on a two-to-one basis, one unit of the OTU frame is reconstructed from the two optical subcarriers.

  In addition, the multicarrier optical transmission system 100 according to the present embodiment may further include an optical network control device that controls operations of the optical transmitter 110 and the optical receiver 120.

  The optical network control apparatus notifies the optical transmitter 110 and the optical receiver 120 of the position on the frequency axis of the predetermined optical subcarrier described above. In addition, the optical network control device manages information on the used band for each optical link of the multicarrier optical transmission system 100. That is, when a communication request is received, the number of optical subcarriers of the optical fiber link used for connecting the transmission / reception nodes, the use frequency, the modulation method, the use band, and the like are determined. And the optical transmitter in an optical node is controlled via the node control part accommodated in each communication node.

  In the multicarrier optical transmission system 100 according to the present embodiment, as described above, the optical network control device is configured to notify the optical transmitter 110 and the optical receiver 120 of the position on the frequency axis of a predetermined optical subcarrier. Therefore, according to the present embodiment, it is possible to reduce the number of processes for monitoring the quality of the transmission signal without greatly changing the function of the optical network control device.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 2A shows a schematic diagram of the configuration and optical output of the optical transmitter according to the present embodiment. The optical transmitter 200 of this embodiment is used in a multicarrier optical transmission system.

  The optical transmitter 200 includes three functional blocks, a client side interface unit 210, a framer unit 220, and a line side interface unit 230. The client-side interface unit 210 accommodates various client signals such as a LAN (Local Area Network) signal and an SDH (Synchronous Digital Hierarchy) signal. The client signal is divided into a plurality of electrical processing lanes by the client side interface unit 210 and output to the framer unit 220.

  The framer unit 220 multiplexes a plurality of input electrical processing lanes with respect to the client signal, and generates an OTU frame. Here, it is assumed that the framer unit 220 generates an OTU frame at a constant throughput (processing speed). That is, the throughput for generating the OTU frame is determined by the performance of the devices constituting the framer unit 220. By generating the OTU frame, overhead (Overhead: OH) information and forward error correction (FEC) code information are added in addition to the payload portion for storing client information. With such OTU framing, client data becomes highly reliable and transmission data suitable for long-distance transmission. The generated OTU frame is output to the line side interface unit 230.

  The line side interface unit 230 includes a plurality of optical transmission modules 240, 250, 260 and an optical multiplexing block 270. The line side interface unit 230 maps the OTU frame to a plurality of optical subcarriers by the optical transmission modules 240, 250, and 260, and optically transmits the OTU frame through the optical multiplexing block 270.

In addition, the optical receiver used in the multicarrier optical transmission system together with the optical transmitter 200 of the present embodiment can be configured to include a line side interface unit, a deframer unit, and a client side interface unit.
The optical receiving module constituting the line side interface unit receives a plurality of optical subcarriers and performs a deskew process between the plurality of optical subcarriers using an MLD (Multi Lane Distribution) technique or the like. Thereafter, the deframer unit reconfigures the OTU frame, extracts the client data, and outputs it to the client side interface unit.

  Here, the optical transmitter 200 according to the present embodiment uses a predetermined optical subcarrier including at least an optical subcarrier located at an end of a plurality of optical subcarriers arranged continuously on the frequency axis. A unit optical transmission frame that is one unit of the optical transmission frame is transmitted. Specifically, for example, as shown in FIG. 2B, it is assumed that a plurality of optical subcarriers S201 to S206 are continuously arranged on the frequency axis. At this time, the optical transmitter 200 transmits a single OTU frame for monitoring the transmission quality of the optical transmission signal on the receiving side with respect to the two optical subcarriers S201 and S206 at the extreme ends of the continuous optical subcarriers. It was set as the structure to map. Here, it is assumed that the optical transmission module 240 transmits the two optical subcarriers at the extreme ends described above. The optical transmission module 240 includes at least a frame division function unit 241 and an LD / modulator unit 242.

  Next, the operation of the optical transmitter 200 according to the present embodiment will be described in more detail with reference to FIG. FIG. 3 is a block diagram illustrating the configuration of the framer unit 220 and the optical transmission modules 240, 250, and 260 of the optical transmitter 200, and a schematic diagram illustrating mapping to optical subcarriers.

  Here, the operation of the optical transmitter 200 will be described based on the following specific numerical examples. The client data capacity is 300 Gbps, the throughput per optical subcarrier is 50 Gbps, and the throughput of OTU frame generation is 100 Gbps. The number of optical subcarriers is 6, the number of optical transmission modules as line side interfaces is 3, and the number of optical subcarriers per optical transmission module is 2.

  In this case, client data of 300 Gbps is accommodated in the client-side interface unit 210, and then divided into parallel lanes and connected to the framer unit 220.

  The framer unit 220 generates three OTU frames F210, F220, and F230 in units of 100 Gbps from a 300 Gbps client signal. The three OTU frames F210, F220, and F230 are connected to the optical transmission modules 240, 250, and 260 included in the line-side interface unit 230. Here, each optical transmission module 240, 250, 260 divides the OTU frame into two. Taking the optical transmission module 240 as an example, a 100 Gbps OTU frame F210 is divided into two to form OTU frames F211 and F212, which are respectively mapped to two optical subcarriers S201 and S206 having a throughput of 50 Gbps.

  Here, of the three optical transmission modules 240, 250, and 260, two optical subcarriers S201 and S206 transmitted from the optical transmission module 240 are assigned to the subcarriers at the extreme ends of the six optical subcarriers. . The positions of the remaining four optical subcarriers on the frequency axis are not limited. The configuration of the optical transmitter 200 according to the present embodiment is not limited by the numerical examples described above.

  On the other hand, on the receiving side, six optical subcarriers are received by three optical receiving modules for each of two optical subcarriers, and deskew processing is performed. At this time, it is possible to analyze the deterioration of the transmission quality by receiving the optical subcarriers located at the extreme ends with one optical receiving module and reconfiguring the OTU frame for monitoring the transmission quality.

  As described above, in this embodiment, the OTU frame F210 allocated to the optical transmission module 240 is a single OTU frame for monitoring the transmission quality of the optical transmission signal on the receiving side. The OTU frame F210 is mapped to the two optical subcarriers S201 and S206 located at both ends of a plurality of continuous optical subcarriers. By adopting such a configuration, it is possible to reduce the number of optical subcarrier monitors and to obtain a highly reliable multicarrier optical transmission system. That is, even when a flexible frequency grid is introduced into the multicarrier optical transmission system, an increase in the number of processes for monitoring the signal quality of the optical carrier can be suppressed.

  Here, among the plurality of optical subcarriers continuously arranged on the frequency axis, the optical subcarriers located at the extreme ends are most affected by the band narrowing due to the wavelength filter and the influence from the adjacent channel. Therefore, it is easily affected by signal quality degradation due to transmission. That is, it is possible to comprehensively monitor the signal quality of an optical carrier by monitoring only the optical subcarriers at the extreme ends of a plurality of optical subcarriers arranged continuously.

  The predetermined optical subcarrier that transmits a unit optical transmission frame, which is a unit of the optical transmission frame, is not limited to only two optical subcarriers positioned at the extreme ends. The number of predetermined optical subcarriers at this time can be equal to or greater than a value obtained by dividing the processing speed (throughput) for generating an optical transmission frame by the transmission speed (throughput) in the optical subcarrier.

  More specifically, the throughput amount of an OTU frame as an optical transmission frame is the ITU-T recommendation G.264. It is standardized at 709 and is a constant value. On the other hand, the throughput of the optical subcarrier is not necessarily constant, and depends on the distance between the optical transmitter and the optical receiver and the used wavelength bandwidth. Therefore, when the throughput of the OTU frame is larger than the throughput of the optical subcarrier, it is necessary to divide the OTU frame and transmit it by the number of optical subcarriers corresponding to the number of divisions.

  Further, the unit optical transmission frame may be transmitted by an optical subcarrier located at a position other than the end portion among the plurality of optical subcarriers. In this case, it is possible to effectively monitor signal quality degradation due to nonlinear effects between optical subcarriers.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 4A shows the configuration of the optical transmitter according to the present embodiment. The optical transmitter 200 of this embodiment is used in a multicarrier optical transmission system.

  The optical transmitter 200 according to the present embodiment is a unit that is a unit of an optical transmission frame by using a plurality of optical subcarriers arranged in a plurality of multi-optical carrier regions that are spaced apart from each other on the frequency axis. The optical transmission frame is transmitted. That is, the second embodiment is different from the second embodiment in that a plurality of optical subcarriers are not continuously arranged on the frequency axis.

  Such a configuration is effective when a part of the continuous optical frequency band has already been used and a discontinuous optical frequency band must be used when a new optical path is formed. The optical network control device holds information regarding the use status of such an optical frequency band. The optical transmitter 200 according to the present embodiment divides an OTU frame generated from client data into optical subcarriers in a plurality of multi-optical carrier regions arranged discontinuously on the frequency axis under the control of the optical network control device. Then transmit. In the present embodiment, as shown in FIG. 4B, an OTU frame for monitoring transmission quality is assigned to the two optical subcarriers S311 and S313 at the extreme ends for each of the multi-optical carrier regions R310 and R320. .

  Next, the operation of the optical transmitter 200 according to the present embodiment will be described in more detail with reference to FIG. FIG. 5 is a block diagram showing configurations of the framer unit 220 and the optical transmission modules 240, 250, and 260 of the optical transmitter 200, and a schematic diagram showing mapping to optical subcarriers.

  Here, the operation of the optical transmitter 200 will be described based on the following specific numerical examples. The client data capacity is 300 Gbps, the throughput per optical subcarrier is 50 Gbps, and the throughput of OTU frame generation is 100 Gbps. The total number of optical subcarriers is 6, and it is assumed that three optical subcarriers are continuously arranged in the multi-optical carrier regions R310 and R320, respectively. In addition, the number of optical transmission modules provided in the line side interface unit is three, and the number of optical subcarriers per optical transmission module is two.

  In this case, client data of 300 Gbps is accommodated in the client-side interface unit 210, and then divided into parallel lanes and connected to the framer unit 220.

  The framer unit 220 generates three OTU frames F210, F220, and F230 in units of 100 Gbps from a 300 Gbps client signal. The three OTU frames F210, F220, and F230 are connected to the optical transmission modules 240, 250, and 260 included in the line-side interface unit 230. Here, each optical transmission module 240, 250, 260 divides the OTU frame into two. Taking the optical transmission module 240 as an example, a 100 Gbps OTU frame F210 is divided into two to form OTU frames F211 and F212, which are respectively mapped to two optical subcarriers S311 and S313 having a throughput of 50 Gbps. The configuration of the optical transmitter 200 according to the present embodiment is not limited by the numerical examples described above.

  In the present embodiment, as shown in FIG. 5, the plurality of optical subcarriers are respectively disposed in a plurality of multi-optical carrier regions R310 and R320 that are spaced apart from each other on the frequency axis. That is, not all of the plurality of optical subcarriers are continuously arranged on the frequency axis. Therefore, when it is necessary to divide and map the OTU frame generated from the client data into a plurality of non-contiguous multi-optical carrier regions, mapping is performed for the optical subcarriers at the extreme ends for each multi-optical carrier region. The configuration is to be performed.

  This will be described more specifically with reference to FIG. The OTU frames F210 and F220 assigned to the optical transmission module 240 and the optical transmission module 250 are set as a single OTU frame for monitoring the transmission quality of the optical transmission signal on the receiving side. These OTU frames F210 and F220 are used as the two optical subcarriers (S311 and S313, and S321 and S323) at the extreme ends of the three consecutive optical subcarriers included in the multi-optical carrier regions R310 and R320, respectively. It was set as the structure to map. In addition, the position on the frequency of the two optical subcarriers to which the remaining OTU frame F230 is mapped is not limited.

  On the other hand, on the receiving side, six optical subcarriers are received by three optical receiving modules for each of two optical subcarriers. However, in this embodiment, six optical subcarriers are transmitted for each multi-optical carrier region including three consecutive optical subcarriers. Therefore, the four optical subcarriers arranged at both ends of the multi-optical carrier region are received by the two optical receiving modules. The transmission quality of the optical transmission signal can be analyzed from the OTU frame mapped to the four optical subcarriers.

  As described above, according to the multicarrier optical transmission system using the optical transmitter according to the present embodiment, even when it is necessary to use a discontinuous optical frequency band when forming an optical path, An increase in the number of processes for monitoring the signal quality of the optical carrier can be suppressed.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 6 is a block diagram showing a configuration of an optical transmitter 300 according to the fourth embodiment and a schematic diagram of optical output. FIG. 7 is a schematic diagram for explaining optical transmission frame division processing and mapping to optical subcarriers in the optical transmitter 300 according to the present embodiment. The optical transmitter 300 of this embodiment is used in a multicarrier optical transmission system.

  The optical transmitter 300 according to the present embodiment is different from the second and third embodiments in that the optical subcarriers S331 to S336 and the OTU frames F331 to F336 constituting the multicarrier are mapped on a one-to-one basis. . In this case, transmission quality information can be extracted from the OTU frames F331 and F336 mapped to the optical subcarriers S331 and S336 at the extreme ends in the optical receiver that constitutes the multicarrier optical transmission system together with the optical transmitter 300.

  Next, the operation of the optical transmitter 300 will be described based on the following specific numerical examples. The client data capacity is 600 Gbps, the throughput per optical subcarrier is 100 Gbps, and the throughput for OTU frame generation is 100 Gbps. The number of optical subcarriers is 6, the number of optical transmission modules provided in the line side interface unit is 6, and the number of optical subcarriers per optical transmission module is 1. Here, there is a one-to-one correspondence between the throughput for generating an OTU frame and the throughput per optical subcarrier. The configuration of the optical transmitter 300 according to the present embodiment is not limited by the numerical examples described above.

  In this case, the client data of 600 Gbps is accommodated in the client-side interface unit 210, and then divided into parallel lanes and connected to the framer unit 320.

  As shown in FIG. 7, the framer unit 320 generates six OTU frames F331 to F336 in units of 100 Gbps from a 600 Gbps client signal. The six OTU frames F331 to F336 are connected to the respective optical transmission modules 341 to 346 included in the line side interface unit 330. Here, each of the optical transmission modules 341 to 346 maps a 100 Gbps OTU frame to one optical subcarrier having a throughput of 100 Gbps and transmits it. On the receiving side, transmission quality monitor information can be acquired only from the OTU frames F331 and F336 mapped to the optical subcarriers S331 and S336 at the extreme ends of the plurality of optical subcarriers.

  As described above, according to the optical transmitter 300 of the present embodiment, it is possible to obtain a highly reliable multicarrier optical transmission system with a reduced number of monitors of optical subcarriers. That is, even when a flexible frequency grid is introduced into the multicarrier optical transmission system, an increase in the number of processes for monitoring the signal quality of the optical carrier can be suppressed.

  The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the invention described in the claims, and it is also included within the scope of the present invention. Not too long.

DESCRIPTION OF SYMBOLS 100 Multicarrier optical transmission system 110, 200, 300 Optical transmitter 111 Client signal reception part 112 Optical transmission frame accommodating part 113 Optical modulation part 120 Optical receiver 121 Multicarrier optical signal receiving part 122 Optical transmission frame reproduction | regeneration part 123 Monitor part 124 Client signal sending unit 210 Client side interface unit 220, 320 Framer unit 230, 330 Line side interface unit 240, 250, 260, 341-346 Optical transmission module 241 Frame division function unit 242 LD / modulator unit 270 Optical multiplexing block S201, S206, S311, S313, S321, S323, S331 to S336 Optical subcarriers F210, F220, F230, F211, F212, F331 to F336 OTU frame 310, R320 multi optical carrier region

Claims (16)

A client signal is accommodated in an optical transmission frame, and a unit optical transmission frame, which is a unit of the optical transmission frame, is transmitted by a predetermined optical subcarrier among a plurality of optical subcarriers arranged continuously on the frequency axis. An optical transmitter for transmission;
Light that receives the plurality of optical subcarriers , reconstructs the unit optical transmission frame from the predetermined optical subcarriers that are part of the plurality of optical subcarriers, and monitors signal quality using the unit optical transmission frames A multi-carrier optical transmission system having a receiver; The multicarrier optical transmission system according to claim 1, wherein the predetermined optical subcarrier includes at least an optical subcarrier located at an end of the plurality of optical subcarriers. The multicarrier optical transmission system according to claim 1, wherein the predetermined optical subcarrier is a single optical subcarrier among the plurality of optical subcarriers. The predetermined optical subcarriers are two or more optical subcarriers of the plurality of optical subcarriers;
The multi-carrier optical transmission system according to claim 1, wherein the optical transmitter divides the unit optical transmission frame and transmits the divided unit optical transmission frame by the two or more optical subcarriers. 5. The multicarrier according to claim 1, wherein the number of the predetermined optical subcarriers is equal to or greater than a value obtained by dividing a processing speed for generating the optical transmission frame by a transmission speed in the optical subcarrier. Optical transmission system. The multi-carrier optical transmission system according to any one of claims 1 to 5, wherein the plurality of optical subcarriers are respectively disposed in a plurality of multi-optical carrier regions that are spaced apart from each other on a frequency axis. The optical transmitter is
A client signal receiving unit for receiving the client signal;
An optical transmission frame storage unit for storing the client signal in the optical transmission frame;
An optical modulation unit that transmits a multicarrier optical signal including a unit frame optical signal obtained by modulating the predetermined optical subcarrier using the unit optical transmission frame, and
The optical receiver is:
A multicarrier optical signal receiving unit that receives the multicarrier optical signal and demodulates the unit frame optical signal;
An optical transmission frame regenerator that reconstructs the unit optical transmission frame from the demodulated unit frame optical signal;
A monitor unit for monitoring signal quality using the unit optical transmission frame;
The multicarrier optical transmission system according to any one of claims 1 to 6, further comprising: a client signal transmission unit that extracts and transmits the client signal from the optical transmission frame including the unit optical transmission frame. An optical network control device for controlling operations of the optical transmitter and the optical receiver;
The multi-carrier optical transmission according to any one of claims 1 to 7, wherein the optical network control device notifies the optical transmitter and the optical receiver of a position on a frequency axis of the predetermined optical subcarrier. system. Receiving a plurality of optical subcarriers partially including a predetermined optical subcarrier containing a unit optical transmission frame that is a unit of the optical transmission frame, and reconfiguring the unit optical transmission frame from the predetermined optical subcarrier And an optical receiver for monitoring signal quality by the unit optical transmission frame. The plurality of optical subcarriers are continuously arranged on the frequency axis,
The optical receiver according to claim 9, wherein the predetermined optical subcarrier includes at least an optical subcarrier located at an end of the plurality of optical subcarriers. The client signal is accommodated in an optical transmission frame,
A unit optical transmission frame that is a unit of the optical transmission frame is transmitted by a predetermined optical subcarrier among a plurality of optical subcarriers arranged continuously on the frequency axis,
Receiving the plurality of optical subcarriers;
Reconfiguring the unit optical transmission frame from the predetermined optical subcarriers that are part of the plurality of optical subcarriers;
A multicarrier optical transmission method for monitoring signal quality by the unit optical transmission frame.


The multicarrier optical transmission method according to claim 11, wherein the predetermined optical subcarrier includes at least an optical subcarrier located at an end of the plurality of optical subcarriers. The multicarrier optical transmission method according to claim 11 or 12, wherein the predetermined optical subcarrier is a single optical subcarrier among the plurality of optical subcarriers. The predetermined optical subcarriers are two or more optical subcarriers of the plurality of optical subcarriers;
The multi-carrier optical transmission according to claim 11 or 12, wherein when transmitting the unit optical transmission frame, the unit optical transmission frame is divided, and the divided unit optical transmission frame is transmitted by the two or more optical subcarriers. Method. The multicarrier according to any one of claims 11 to 14, wherein the number of the predetermined optical subcarriers is equal to or greater than a value obtained by dividing a processing speed for generating the optical transmission frame by a transmission speed in the optical subcarrier. Optical transmission method. The multicarrier optical transmission method according to any one of claims 11 to 15, wherein the plurality of optical subcarriers are respectively disposed in a plurality of multioptical carrier regions that are spaced apart from each other on a frequency axis.

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