JP5427650B2 - Optical communication system and optical signal branching apparatus - Google Patents

Description

  The present invention relates to a technique for improving wavelength path quality in an optical communication system for setting wavelength multicast, that is, a wavelength path with one-to-many connection.

  In order to simultaneously transmit a large-capacity content signal from a distribution source to a plurality of arbitrary locations using a communication network, for example, it is conceivable to apply the IP multicast technique described in Non-Patent Document 1. However, for example, in order to transmit an uncompressed Super Hi-Vision signal for broadcasting, a transfer speed of several tens of Gbps is necessary. Distribution of such a large amount of traffic using IP multicast technology realizes IP multicast. It may not be realistic in terms of processing load on each device.

“Overview of IP multicast technology”, [online], Cisco Systems GK, [searched on January 15, 2010], Internet <URL: http: // www. cisco. com / web / JP / product / hs / ios / multicast / tech / mcst_ovr. html>

  Transferring large-capacity content data using a wavelength path is appropriate from the viewpoint of processing load on the apparatus because signal processing at the relay node can be reduced. FIG. 5 shows a configuration example for realizing a one-to-many connection wavelength path tree. Each of the optical couplers 50, 51, 52, 53, and 54 splits an input optical signal into two at a fixed branch ratio. The large-capacity content data output from the distribution device 10 to the optical coupler 50 is received by the reception devices 11, 12, and 13, respectively. In this way, a large-capacity content data can be simultaneously distributed to a plurality of locations at the same wavelength by the one-to-many connection wavelength path tree.

  In the configuration shown in FIG. 5, reference numerals 100, 200, 300, 400, 500, and 600 are optical links (optical transmission lines) that include zero or one or more optical amplifiers. When the path length from the distribution apparatus 10 to each of the receiving apparatuses 11, 12, and 13 and the number of optical amplifiers existing in the path are different for each receiving apparatus, the optical coupler simply branches in two at a fixed branching ratio. If the receiver is used, the OSNR (optical signal-to-noise ratio) of the optical signal received by each receiving apparatus will be different for each receiving apparatus. That is, the quality of the wavelength path received by each receiving apparatus varies.

  Therefore, the present invention is an optical communication system for setting a wavelength path of one-to-many connection, and reduces the difference in received signal quality in each receiving apparatus that receives an optical signal from the wavelength path, thereby improving the quality of the wavelength path. It is an object of the present invention to provide an optical communication system and an optical signal branching device used in the optical communication system.

According to the optical communication system of the present invention,
Of the input optical signals having one or more wavelengths, an optical signal having a selected wavelength is output from one or more arbitrary output ports, and an optical signal having the selected wavelength is output from two or more output ports. in this case, the wavelength selective switch means which can set the branching ratio, seen plurality including an optical signal branching device provided with a control means for setting the branching ratio in the wavelength selection switch means, one-to-many connections wavelength path An optical communication system capable of setting a tree and simultaneously distributing content from a distribution device to a plurality of reception devices at the same wavelength, and outputting optical signals of the selected wavelength from two or more output ports The branching ratio to be set in this case is the maximum for each output port of the sum of the cost values of one or more optical links through which optical signals having wavelengths that are output from each output port and reach one or more receiving devices pass. Based on value Determined, the cost value of the optical link is characterized by a value indicating the degree of deterioration of the optical signal-to-noise ratio optical signal passing through the optical link are subjected.

According to another embodiment of the optical communication system according to the invention,
The cost value of the optical link is also preferably a value calculated from the number of optical amplifiers included in the optical link or the length of the optical link.

According to another embodiment of the optical communication system according to the present invention,
When the control means receives a control signal instructing the setting of a wavelength path, the control means holds the path information of the wavelength path included in the control signal and the optical signal branching device, or in the optical communication system It is also preferable to determine the branching ratio based on the cost value held by the database device provided in the network and the cost value of the optical link obtained by accessing the database.

Furthermore, according to another embodiment of the optical communication system according to the present invention,
The optical communication system includes a device for setting a wavelength path, and the device for setting the wavelength path is a cost value held by the own device or a database device provided in the optical communication system. Control for determining the branching ratio in the optical signal branching device that becomes the branching point of the wavelength path based on the cost value of the optical link obtained by accessing the database, and setting the determined branching ratio for the wavelength path It is also preferable to notify each optical signal branching device by a signal.

Furthermore, according to another embodiment of the optical communication system according to the present invention,
The optical communication system includes a network management apparatus, and the network management apparatus accesses and acquires a cost value / database held by the own apparatus or a database apparatus provided in the optical communication system. Based on the cost value of the optical link, it is also preferable to determine the branching ratio in the optical signal branching device that becomes the branching point of the wavelength path and to notify the determined branching ratio to each optical signal branching device.

According to the optical signal branching device according to the present invention,
Of the input optical signals having one or more wavelengths, an optical signal having a selected wavelength is output from one or more arbitrary output ports, and an optical signal having the selected wavelength is output from two or more output ports. In this case, an optical signal branching device for configuring the optical communication system , comprising wavelength selective switch means capable of setting the branching ratio, and control means for setting the branching ratio in the wavelength selective switch means, When the control means receives a control signal instructing setting of a wavelength path including a route from two or more output ports to one or more receiving devices, the control means holds the device, or externally Cost values held by the database device ・ Accessing the database, the cost values of one or more optical links through which optical signals of wavelengths that are output from each output port and reach one or more receiving devices pass. Obtaining a maximum value for each output port of the sum of the cost values, determining a branching ratio based on the maximum value, and determining a cost value of the optical link as an optical signal received by the optical signal that has passed through the optical link. It is a value indicating the degree of deterioration of the signal-to-noise ratio.

  In order to distribute signals from one distribution device to multiple reception devices, when setting one-to-many wavelength paths, the variation in the optical signal-to-noise ratio of the wavelength paths received by each reception device is suppressed. Can be made fair and improved. Accordingly, it is possible to improve the quality of the wavelength path having a long path length and using many optical amplifiers, and the expandability of the wavelength path tree can be improved.

It is a block diagram of the optical communication system by this invention. It is a block diagram of the optical signal branching apparatus by this invention. It is a sequence diagram of branch ratio determination. It is a figure for demonstrating the determination method of a branching ratio. It is a network block diagram in the case of providing a one-to-many connection wavelength path using a coupler.

  EMBODIMENT OF THE INVENTION The form for implementing this invention is demonstrated in detail below using drawing. FIG. 1 is a configuration diagram of an optical communication system according to the present invention. The optical communication system includes a distribution device 10, optical signal branching devices 1, 2, 3, 4 and 5, and receiving devices 11, 12 and 13. Have. In FIG. 1, the optical signal branching devices 1 and 2 are connected by an optical link 100, the optical signal branching devices 1 and 3 are connected by an optical link 200, the optical signal branching devices 3 and 4 are connected by an optical link 500, and the optical signal branching device 3 is connected. 5 is connected by an optical link 300, the receiving device 11 is connected to the optical signal branching device 2, the receiving device 12 is connected to the optical signal branching device 3, and the receiving device 13 is connected to the optical signal branching device 13. This is an example. Moreover, although the optical signal branching devices 1 to 5 shown in FIG. 1 have one input and two outputs, they may have three or more output ports.

  FIG. 2 is a configuration diagram of the optical signal branching devices 1 to 5 according to the present invention. As shown in FIG. 2, the optical signal branching devices 1 to 5 include a wavelength selective switch unit 21, a control unit 22, and a database unit 23. The wavelength selective switch unit 21 is a wavelength selective switch having a D & C (Drop and Continue) function and capable of setting the branching ratio. That is, the wavelength selective switch unit 21 can output each of the optical signals having one or more wavelengths input to the input port from any one or more output ports, and can output two or more outputs. When outputting from a port, the branching ratio can be set. Note that the wavelength selective switch unit 21 does not necessarily output optical signals of all wavelengths input to the input port from any output port, but blocks optical signals of unnecessary wavelengths. That is, it is possible to prevent output from any output port. That is, the optical signal output from the output port can be selected from the input optical signals of the respective wavelengths.

  The database unit 23 holds a cost value / database indicating the cost value of each optical link. The cost value of the optical link is an arbitrary index indicating the degree of deterioration of the OSNR received by the optical signal that has passed through the optical link. In this embodiment, the number of optical amplifiers included in the optical link is the cost value. To do. However, any index indicating the degree of deterioration of OSNR received by the optical signal that has passed through the optical link, such as the fiber length or the value obtained from both the optical amplifier and the fiber length, can be used as the cost value of the optical link.

  When the control unit 22 receives the control signal instructing the setting of the wavelength path, the control unit 22 branches based on the cost value / database held in the database unit 23 and the path information of the wavelength path included in the control signal. The ratio is obtained, and the obtained branching ratio is set in the wavelength selective switch unit 21. Note that ERO (Explicit Route Object) information of a Path signal of GMPLS (Generalized Multi-Protocol Label Switching) can be used as a control signal for setting a wavelength path. This is shown in FIG.

  Note that the branching ratio is calculated in the same manner not only when a one-to-many path is set simultaneously but also when a part that branches later is added. Specifically, when a 1: 2 wavelength path from the distribution device 10 to the reception device 11 and the reception device 13 is set, a portion from the optical signal branching device 3 to the reception device 12 is added later. Then, the control unit 22 of the optical signal branching device 3 that has received the path setting control signal for the part leading to the receiving device 12 to be added recalculates the branching ratio and uses the recalculated value as the wavelength of the optical signal branching device 3. The selection switch unit 21 is set.

  Hereinafter, a method of obtaining the branching ratio will be described based on the configuration of FIG. In FIG. 4, reference numeral 10 denotes a distribution apparatus, reference numerals 1 to 5 denote optical signal branching apparatuses, reference numerals 11 to 16 denote reception apparatuses, and arrows denote optical links. It is assumed that a one-to-many connection path leading to is set. In other words, it is assumed that the distribution device 10 is trying to distribute a signal other than the reception device 16. The numbers beside each optical link are the number of optical amplifiers included in the optical link. Therefore, the cost values / databases held by the optical signal branching apparatuses 1 to 5 are as follows.

  The branching ratio in the optical signal branching device is the ratio of the maximum value of the sum of the cost values of one or more optical links through which the branched signal of each wavelength passes after branching of the wavelength path in the optical signal branching device. . Specifically, the wavelength path is branched into two in the optical signal branching device 1, and the signal output to the link A side reaches only the receiving device 11 via the link C. Therefore, the sum of the cost values on the link A side The maximum value is 3. On the other hand, the signal output to the link B side is sent to the receiving device 12 via the link E, to the receiving device 13 via the links F and G, to the receiving device 14 via the links F, H and I, and to the links F, H and Each of the receivers 15 is reached via J. The total cost value up to the receiving device 12 is 4, the total cost value up to the receiving device 13 is 8, the total cost value up to the receiving device 14 is 12, and the cost value up to the receiving device 15 is Since the sum is 14, the maximum sum of the cost values on the link B side is 14. Therefore, the branching ratio in the optical signal branching apparatus 1 is set to link A side: link B side = 3: 14.

  Further, since there is no need to set a wavelength path for the receiving device 16, the branching ratio in the optical signal branching device 2 is link C side: link D side = 1: 0. Further, in the optical signal branching device 3, the total cost value on the link E side is 2, and the total cost value on the link F side is 6 for the receiving device 13, 10 for the receiving device 14, and the receiving device 15. Therefore, the branching ratio in the optical signal branching device 3 is link E side: link F side = 2: 12. Similarly, the branching ratio in the optical signal branching device 4 is link G side: link H side = 2: 8, and the branching ratio in the optical signal branching device 5 is link I side: link J side = 2: 4.

  The optical signal branching device according to the present invention holds at least the cost values of all the optical links on the downstream side as a cost value / database, and the path of the wavelength path included in the control signal instructing the setting of the wavelength path From the information, for each output port, the maximum value of the sum of the cost values of one or more optical links through which the signal of the output wavelength passes is obtained, and the branching ratio is determined based on the maximum value.

  In the example shown in FIG. 4, when the optical signal branching devices 1 to 5 set the branching ratio as described above, the OSNR of the optical signal received by each receiving device and the branching instead of the optical signal branching devices 1 to 5 The following table shows the OSNR of the optical signal received by each receiving apparatus when an optical coupler with a ratio of 1: 1 is used. Note that the noise figure of each optical amplifier is 8 dB. In addition, when an optical coupler with a branching ratio of 1: 1 is used, the gain of each optical amplifier is adjusted so that the optical power input to each optical amplifier is −12 dBm, and the gain of each optical amplifier is It is assumed that it is controlled to be constant.

また、上記一定利得の光増幅器に代えて、その出力を常に一定に調整する、出力一定制御光増幅器を使用した場合における、各受信装置が受信する光信号のＯＳＮＲを以下の表に示す。なお、その他の条件は、上記と同じである。

The following table shows the OSNR of the optical signal received by each receiver when using a constant output control optical amplifier that constantly adjusts its output in place of the constant gain optical amplifier. Other conditions are the same as above.

  As is clear from the above tables, according to the present invention, it is possible to suppress the variation in the OSNR of the wavelength paths received by each receiving apparatus, compared to the case where the branching ratio is fixed. In addition, by using the wavelength selective switch unit 21, it is possible to stop outputting wavelengths in unnecessary directions, and therefore it is possible to prevent wavelength collision.

  In the above-described embodiment, each optical signal branching device holds a cost value / database. However, a database device that holds the cost value / database is provided in the optical communication system, and each optical signal branching device has a database. The form which accesses an apparatus and acquires a link cost value may be sufficient. In this case, the database unit 23 in FIG. 2 can be omitted.

  Further, in each optical signal branching device, instead of obtaining the branching ratio, for example, the distribution device 10 that requests the setting of the wavelength path has the cost of the database device provided inside the distribution device 10 or installed outside. Access to the value / database, obtain the cost value of each optical link, obtain the branching ratio at each optical signal branching device based on the wavelength path to be set, and branch each optical signal in the control signal instructing the wavelength path setting It may be in the form of notifying the device of the branching ratio. In this case, the database unit 23 in FIG. 2 can be omitted, and the control unit 22 in FIG. 2 sets the designated branch ratio in the wavelength selective switch unit 21.

  Further, a network management device is provided in the optical communication system, and the network management device obtains a branching ratio in each optical signal branching device based on the set wavelength path, and the obtained branching ratio is determined for each optical signal branching device. May be notified. As described above, the cost value / database may be provided externally or may be provided inside the network management apparatus.

1, 2, 3, 4, 5 Optical signal branching device 10 Distribution device 11, 12, 13, 14, 15, 16 Receiving device 21 Wavelength selection switch unit 22 Control unit 23 Database unit 50, 51, 52, 53, 54 Coupler 100, 200, 300, 400, 500, 600 Optical link

Claims (6)

Of the input optical signals having one or more wavelengths, an optical signal having a selected wavelength is output from one or more arbitrary output ports, and an optical signal having the selected wavelength is output from two or more output ports. in this case, the wavelength selective switch means which can set the branching ratio, seen plurality including an optical signal branching device provided with a control means for setting the branching ratio in the wavelength selection switch means, one-to-many connections wavelength path An optical communication system capable of setting a tree and simultaneously distributing content from a distribution device to a plurality of reception devices at the same wavelength ;
The branching ratio set when the optical signal of the selected wavelength is output from two or more output ports is 1 through which the optical signal of the wavelength that is output from each output port and reaches one or more receiving devices passes. Determine based on the maximum value for each output port of the sum of the cost values of two or more optical links,
The cost value of the optical link is a value indicating the degree of deterioration of the optical signal-to-noise ratio received by the optical signal that has passed through the optical link.
Optical communication system. The cost value of the optical link is a value calculated from the number of optical amplifiers included in the optical link or the length of the optical link.
The optical communication system according to claim 1. When the control means receives a control signal instructing the setting of a wavelength path, the control means holds the path information of the wavelength path included in the control signal and the optical signal branching device, or in the optical communication system The branching ratio is determined based on the cost value held by the database device provided in the database and the cost value of the optical link obtained by accessing the database.
The optical communication system according to claim 1 or 2. The optical communication system includes a device for setting a wavelength path,
The apparatus for setting the wavelength path is based on the cost value of the optical link held by the own apparatus or by the database device provided in the optical communication system and the cost of the optical link obtained by accessing the database. Determining the branching ratio in the optical signal branching device that becomes the branching point of the wavelength path, and notifying each optical signal branching device of the determined branching ratio by a control signal for setting the wavelength path;
The optical communication system according to claim 1 or 2. The optical communication system includes a network management device,
The network management apparatus branches the wavelength path based on a cost value held by the own apparatus or a cost value held by a database apparatus provided in the optical communication system and an optical link cost acquired by accessing the database. Determine the branching ratio in the optical signal branching device to be a point, and notify the determined branching ratio to each optical signal branching device,
The optical communication system according to claim 1 or 2. Of the input optical signals having one or more wavelengths, an optical signal having a selected wavelength is output from one or more arbitrary output ports, and an optical signal having the selected wavelength is output from two or more output ports. 2. An optical signal branch for configuring the optical communication system according to claim 1 , further comprising: a wavelength selective switch unit capable of setting the branching ratio; and a control unit configured to set the branching ratio in the wavelength selective switch unit. A device,
When the control means receives a control signal instructing setting of a wavelength path including a route from two or more output ports to one or more receiving devices, the control means holds the device, or externally The cost value held by the database device is accessed. The database is accessed to obtain the cost value of one or more optical links through which optical signals of wavelengths output from each output port and reach one or more receiving devices pass. , Determine the maximum value for each output port of the sum of the cost values, determine the branching ratio based on the maximum value ,
The cost value of the optical link is a value indicating the degree of deterioration of the optical signal-to-noise ratio received by the optical signal that has passed through the optical link.
Optical signal branching device.

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