Patent Application
20180375579
The present invention relates to a communication system and a connector.
A communication network which uses optical fibers is constructed in a core network that connects together metropolises and a metro network that connects together bases in an area. In such a network, a plurality of optical fibers are used in a bundle. Wavelength division multiplexing (WDM) transmission which involves multiplexing a plurality of optical signals having different wavelengths is performed on respective individual optical fibers to realize high-capacity signal transmission (for example, see Non-Patent Literature Shinji Matsuoka, “Ultrahigh-speed Ultrahigh-capacity Transport Network Technology for Cost-effective Core and Metro Networks,” NTT Technical Journal, March 2011, pages 8-12 [[1]]). In order to further increase the transmission capacity, the use of a multi-core fiber (MCF) which is an optical fiber having a plurality of cores instead of an optical fiber (single core fiber: SCF) having one core has been discussed (for example, see Non-Patent Literatures Yutaka Miyamoto and Hirokazu Takenouchi, “Dense Space-division-multiplexing Optical Communications Technology for Petabit-per-second Class Transmission,” NTT Technical Journal, August 2014, pages 52-56 and Kazuyuki Shiraki, “R&D Trends in Optical Fiber and Cable Technology,” NTT Technical Journal, January 2015, pages 59-63[[2 and 3]]).
In a node of a ring network for wavelength division multiplexing transmission which uses SCF, it is necessary to divide multiplexed optical signals in respective wavelengths in order to add and drop (Add/Drop) desired signals from optical signals that are multiplex-transmitted through an optical fiber. When a network is configured using MCF instead of SCF in the future, the number of optical signals will increase as the number of transmission cores and the number of signals divided in respective wavelengths will also increase dramatically. Due to this, when a method similar to Add/Drop in the network which uses SCF is applied to a network which uses an MCF, there is a problem that a device for performing Add/Drop of optical signals in each node becomes complex. Moreover, there is another problem that installation and maintenance of nodes take time and labor.
In view of the above-described problems, an object of the present invention is to provide a communication system and a connector which facilitate adding and dropping of optical signals in nodes connected to a multi-core fiber.
A communication system of a first aspect of the present invention is a communication system which includes three or more nodes; and a multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of the connection between the nodes, wherein one node of the nodes is connected to the multi-core fiber and includes a connector configured to add and drop a signal to and from an allocated core exclusively allocated from among the cores for communication between the one node and another node of the nodes and/or configured to relay a signal transmitted through another core allocated from among the cores for communication between the other nodes in multi-core fibers connected to the one node.
According to a second aspect of the present invention, in the communication system of the first aspect, the connector is further configured to switch an operation of the allocated core to operate to add or drop a signal or to relay a signal.
According to a third aspect of the present invention, in the communication system of the first aspect, each of the nodes is connected to two other nodes.
According to a fourth aspect of the present invention, in the communication system of the first aspect, each of two nodes of the nodes is connected to one of the other nodes, and each of the nodes other than the two nodes is connected to two nodes of the other nodes.
According to a fifth aspect of the present invention, in the communication system of the first aspect, at least one node of the nodes has communication paths directed to all of the other nodes, respectively, and each of the communication paths uses a respective allocated core.
According to a sixth aspect of the present invention, in the communication system of the first aspect, the nodes have communication paths directed to the other nodes, and each of the communication paths uses a respective allocated core.
According to a seventh aspect of the present invention, in the communication system of the sixth aspect, all the nodes have communication paths directed to all of the other nodes, respectively, and each of the communication paths uses a respective allocated core.
According to an eighth aspect of the present invention, in the communication system of the first aspect, the one node has one communication path directed to each communication target node of the other nodes, and the one communication path uses a respective allocated core.
According to a ninth aspect of the present invention, in the communication system of the first aspect, the one node has a communication path directed to each communication target node of the other nodes, and different cores of the cores are used for each communication path.
According to a tenth aspect of the present invention, in the communication system of the first aspect, the one node uses different communication paths for transmission and reception in communication with a communication target nodes of the other nodes, and the allocated core allocated to the communication path for transmission is different from the allocated core allocated to the communication path for reception.
According to an eleventh aspect of the present invention, in the communication system of the first aspect, the one node uses a communication path for transmission and reception in communication with a communication target node of the other nodes, and the core allocated to the communication path is used for transmission and reception.
According to a twelfth aspect of the present invention, in the communication system of the first aspect, the core allocated to the one node is selected from the cores on a basis of a communication quality required for the one node.
According to a thirteenth aspect of the present invention, in the communication system of the first aspect, the one node transmits a signal obtained by multiplexing signals of a plurality of wavelengths between the one node and a communication target node of the nodes via a communication path which uses the allocated core.
A connector of a fourteenth aspect of the present invention is a connector used in a node connected to a multi-core fiber having a plurality of cores, wherein the connector is configured to add and drop a signal to and from an allocated core exclusively allocated for communication of the node in which the connector is used.
According to a fifteenth aspect of the present invention, in the connector of the fourteenth aspect, the connector is further configured to relay a signal transmitted by another core allocated for communication between other nodes between multi-core fibers connected to the node.
According to a sixteenth aspect of the present invention, in the connector of the fifteenth aspect, the connector is further configured to switch an operation of the allocated core to operate to add or drop a signal or to relay a signal.
According to the present invention, it is possible to facilitate adding and dropping of optical signals in nodes connected to a multi-core fiber.
Hereinafter, a communication system and a connector according to an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, elements denoted by the same reference numerals perform similar operations and a redundant description thereof will be omitted appropriately.
Nodes are connected together by multi-core fibers (MCFs) 200-1 to 200-4. The communication system 100 has a physical topology of a single-system one-way ring configuration in which the nodes are connected together by the MCFs 200-1 to 200-4. The transceiving node 110 and the Add/Drop node 120-1 are connected together by the MCF 200-1. The Add/Drop node 120-1 and the Add/Drop node 120-2 are connected together by the MCF 200-2. The Add/Drop node 120-2 and the Add/Drop node 120-3 are connected together by the MCF 200-3. The Add/Drop node 120-3 and the transceiving node 110 are connected together by the MCF 200-4. Each of the MCFs 200-1 to 200-4 of the first embodiment has three cores 201, 202, and 203.
To generalize the description of the configuration of the communication system 100, an Add/Drop node 120-i (1≤i≤n−1) is connected to an Add/Drop node 120-(i+1) by an MCF 200-(i+1). The MCF 200-1 connects together the transceiving node 110 and the Add/Drop node 120-1. The MCF 200-(n+1) connects together the Add/Drop node 120-n and the transceiving node 110.
Each node of the communication system 100 includes a transmitting device (Tx) and a receiving device (Rx) that perform communication between the nodes. Transmitting devices 111-1 to 111-3 and receiving devices 112-1 to 112-3 are provided in the transceiving node 110. A transmitting device 121-1 and a receiving device 122-1 are provided in the Add/Drop node 120-1. A transmitting device 121-2 and a receiving device 122-2 are provided in the Add/Drop node 120-2. A transmitting device 121-3 and a receiving device 122-3 are provided in the Add/Drop node 120-3. The transmitting devices 111-1 to 111-3 generate optical signals to be transmitted to the Add/Drop nodes 120-1 to 120-3, respectively. The receiving devices 112-1 to 112-3 receive optical signals transmitted from the Add/Drop nodes 120-1 to 120-3 and acquire information included in the optical signals. The transmitting devices 121-1 to 121-3 generate optical signals to be transmitted to the transceiving node 110. The receiving devices 122-1 to 122-3 receive optical signals transmitted from the transceiving node 110 and acquire information included in the optical signals.
The transmitting devices 111-1 to 111-3 generate optical signals addressed to the Add/Drop nodes 120-1 to 120-3, respectively. The three optical signals generated by the transmitting devices 111-1 to 111-3 are added to the cores 201-1 to 203-1 of the MCF 200-1, respectively. The receiving devices 112-1 to 112-3 receive optical signals transmitted from the Add/Drop nodes 120-1, 120-2, and 120-3 to nodes included in the receiving devices, respectively. The receiving devices 112-1 to 112-3 receive optical signals from the Add/Drop nodes 120-1 to 120-3 via the cores 201-4 to 203-4 of the MCF 200-4. A fan-in device or a fan-out device is used for adding optical signals to the MCF 200 and dropping optical signals from the MCF 200 in the transceiving node 110.
The fan-in device is a device which is connected to each of the cores in a multi-core fiber and which adds optical signals to the cores. The fan-out device is a device which is connected to each of the cores in a multi-core fiber and which drops each of optical signals propagating through the cores. Since the only difference between the devices is that the propagating directions of optical signals are different, input and output of optical signals to and from a multi-core fiber may be performed using any one of the fan-in device and the fan-out device. Moreover, adding of optical signals addressed to a multi-core fiber and dropping of optical signals from the multi-core fiber may be performed simultaneously using one device.
Connectors 150-1 to 150-3 are provided in the Add/Drop nodes 120-1 to 120-3, respectively. A connector 150-i of an Add/Drop node 120-i (i=1, 2, 3) is connected to an MCF 200-i and an MCF 200-(i+1). A connector 150-i drops an optical signal addressed to a subject node among the optical signals added in the transceiving node 110 from the MCF 200-i. Moreover, the connector 150-i adds optical signals addressed to the transceiving node 110 to the cores of the MCF 200-(i+1).
In the Add/Drop node 120-1, the connector 150-1 drops an optical signal addressed to the subject node from the core 201-1 of the MCF 200-1. The connector 150-1 connects the dropped optical signal to the receiving device 122-1. Moreover, the connector 150-1 adds an optical signal generated by the transmitting device 121-1 to the core 201-2 of the MCF 200-2. The optical signal added to the core 201-2 is an optical signal transmitted from the Add/Drop node 120-1 to the transceiving node 110.
The connector 150-1 connects the cores 202-1 and 203-1 among the cores of the MCF 200-1 to the cores 202-2 and 203-2 among the cores of the MCF 200-2. The connector 150-1 relays optical signals between the MCF 200-1 and the MCF 200-2. The connector 150-1 relays optical signals transmitted through cores other than the cores 201-1 and 201-2 through which an optical signal is added or dropped.
In the Add/Drop node 120-2, the connector 150-2 drops an optical signal addressed to the subject node from the core 202-2 of the MCF 200-2. The connector 150-2 connects the dropped optical signal to the receiving device 122-2. Moreover, the connector 150-2 adds an optical signal generated by the transmitting device 121-2 to the core 202-3 of the MCF 200-3. The optical signal added to the core 202-3 is an optical signal transmitted from the Add/Drop node 120-2 to the transceiving node 110.
The connector 150-2 connects the cores 201-2 and 203-2 among the cores of the MCF 200-2 to the cores 201-3 and 203-3 among the cores of the MCF 200-3. The connector 150-2 relays optical signals between the MCF 200-2 and the MCF 200-3. The connector 150-2 relays optical signals transmitted through cores other than the cores 201-2 and 201-3 through which optical signals are added or dropped.
In the Add/Drop node 120-3, the connector 150-3 drops an optical signal addressed to the subject node from the core 203-3 of the MCF 200-3. The connector 150-3 connects the dropped optical signal to the receiving device 122-3. Moreover, the connector 150-3 adds an optical signal generated by the transmitting device 121-3 to the core 203-4 of the MCF 200-4. The optical signal added to the core 203-4 is an optical signal transmitted from the Add/Drop node 120-3 to the transceiving node 110.
The connector 150-3 connects the cores 201-3 and 202-3 among the cores of the MCF 200-3 to the cores 201-4 and 202-4 among the cores of the MCF 200-4. The connector 150-3 relays optical signals between the MCF 200-3 and the MCF 200-4. The connector 150-3 relays optical signals transmitted through cores other than the cores 203-3 and 203-4 through which optical signals are added or dropped.
The connector 150-i shown in
The other set of ends of the SMFs corresponding to cores that transmit optical signals which are not the Add/Drop target among the cores of the MCF 200-i and the other set of ends of the SMFs corresponding to cores that transmit optical signals which are not the Add/Drop target among the cores of the MCF 200-(i+1) are provided at positions facing each other. In the connector 150-i, optical signals which are not the Add/Drop target are relayed from the MCF 200-i to the MCF 200-(i+1) via the small-diameter SMFs and the SMFs.
In the connector 150-i shown in
One set of ends of the waveguide cores corresponding to the cores that transmit optical signals which are not the Add/Drop target among the cores of the MCF 200-i are provided at positions facing the cores of the MCFs. The other set of ends of the waveguide cores are provided at positions facing the cores that transmit optical signals which are not the Add/Drop target among the cores of the MCF 200-(i+1). The cores that transmit optical signals which are not the Add/Drop target in the MCF 200-i and the MCF 200-(i+1) are connected to waveguide cores in a one-to-one relationship. In the connector 150-i, the optical signals which are not the Add/Drop target are relayed from the cores of the MCF 200-i to the cores of the MCF 200-(i+1) via the waveguide cores.
The waveguide cores may be formed in a three-dimensional space as disclosed in R. R. Thomson, et al., “Ultrafast-laser inscription of a three dimensional fan-out device for multicore fiber coupling applications,” Optics Express, OSA Publishing, 2007, Vol. 15, Issue 18, p. 11691-11697 as well as being formed in a two-dimensional space of a substrate plane.
Optical signals which are not the Add/Drop target are bundled together with the added optical signals after being split by the optical system and are input to the respective cores of the MCF 200-(i+1). In the connector 150-i, the optical signals which are not the Add/Drop target are relayed from the MCF 200-i to the MCF 200-(i+1) via a free space. Although two lenses are used for collimating light output from the fiber and a mirror is used for changing the propagating direction of light in the free space in the drawings, an optical device having the same function may be used.
Although
In the communication system 100 of the first embodiment, optical signals generated by the transmitting device 111-1 of the transceiving node 110 are received by the receiving device 122-1 of the Add/Drop node 120-1 via the core 201-1 of the MCF 200-1 and the connector 150-1. The optical signals generated by the transmitting device 111-2 are received by the receiving device 122-2 of the Add/Drop node 120-2 via the core 202-1 of the MCF 200-1, the connector 150-1, the core 202-2 of the MCF 200-2, and the connector 150-2. The optical signals generated by the transmitting device 111-3 are received by the receiving device 122-3 of the Add/Drop node 120-3 via the core 203-1 of the MCF 200-1, the connector 150-1, the core 203-2 of the MCF 200-2, the connector 150-2, the core 203-3 of the MCF 200-3, and the connector 150-3.
Moreover, the optical signals generated by the transmitting device 121-1 of the Add/Drop node 120-1 are received by the receiving device 112-1 of the transceiving node 110 via the connector 150-1, the core 201-2 of the MCF 200-2, the connector 150-2, the core 201-3 of the MCF 200-3, the connector 150-3, and the core 201-4 of the MCF 200-4. The optical signals generated by the transmitting device 121-2 of the Add/Drop node 120-2 are received by the receiving device 112-2 of the transceiving node 110 via the connector 150-2, the core 202-3 of the MCF 200-3, the connector 150-3, and the core 202-4 of the MCF 200-4. The optical signals generated by the transmitting device 121-3 of the Add/Drop node 120-3 are received by the receiving device 112-3 of the transceiving node 110 via the connector 150-3 and the core 203-4 of the MCF 200-4.
In the communication system 100, the transceiving node 110 has communication paths for transmitting and receiving signals to and from the Add/Drop nodes 120-1 to 120-3. The communication system 100 has a star-type logical topology around the transceiving node 110.
For example, by connecting together the MCFs 200 at each node using any one of the connectors 150 shown in
Although a case in which the MCF 200 has three cores has been described, the MCF 200 may have four or more cores. When the MCF 200 has four or more cores, optical signals may be added and dropped for two or more cores of the Add/Drop node 120.
Moreover, WDM transmission may be performed in each core of the MCF 200. When WDM transmission is performed, optical signals of respective wavelengths need to be split and combined in the Add/Drop node 120.
An optical signal dropped from the core 201-1 of the MCF 200-1 of the connector 150-1 is input to the splitter 124-1. The splitter 124-1 splits the input optical signal in respective wavelengths. The optical signals obtained by splitting are received by the receiving devices 122-1, respectively. The optical signals having different wavelengths generated by the plurality of transmitting devices 121-1 are input to the combiner 123-1. The combiner 123-1 combines the input optical signals and outputs the combined optical signal to the connector 150-1. The connector 150-1 connects the optical signal input from the combiner 123-1 to the core 201-2 of the MCF 200-2 to add the optical signal addressed to the transceiving node 110 to the MCF 200-2.
Even when WDM transmission is performed, the optical signals of the cores 202-1 and 203-1 of the MCF 200-1, which are not the Add/Drop target, are relayed to the cores 202-2 and 203-2 of the MCF 200-2. Due to this, as for optical signals to be relayed, it is not necessary to split and combine optical signals in respective wavelengths at each Add/Drop node. When WDM transmission is performed, the other Add/Drop nodes 120 have a configuration similar to that of the Add/Drop node 120-1.
Nodes are connected together by MCFs 210-1 to 210-4. The transceiving node 110a and the Add/Drop node 120-1 are connected together by the MCF 210-1. The Add/Drop node 120-1 and the Add/Drop node 120-2 are connected together by the MCF 210-2. The Add/Drop node 120-2 and the Add/Drop node 120-3 are connected together by the MCF 210-3. The Add/Drop node 120-3 and the transceiving node 110b are connected together by the MCF 210-4. The MCFs 210-1 to 210-4 of the second embodiment include six cores 211 to 216.
When the description of the configuration of the communication system 100A is generalized, an Add/Drop node 120-i (1≤i≤n−1) is connected to an Add/Drop node 120-(i+1) by an MCF 210-(i+1). The MCF 210-1 connects together the transceiving node 110a and the Add/Drop node 120-1. The MCF 210-(n+1) connects together the Add/Drop node 120-n and the transceiving node 110b.
Each node of the communication system 100A includes either a transmitting device (Tx) and a receiving device (Rx) that perform communication between nodes or a transceiving device (Tx/Rx). Transmitting devices 111-1 to 111-3 and receiving devices 112-1 to 112-3 are provided in the transceiving node 110a. Transceiving devices 125-1 and 126-1 are provided in the Add/Drop node 120-1. Transceiving devices 125-2 and 126-2 are provided in the Add/Drop node 120-2. Transceiving devices 125-3 and 126-3 are provided in the Add/Drop node 120-3. Transmitting devices 111-4 to 111-6 and receiving devices 112-4 to 112-6 are provided in the transceiving node 110b. In the configuration example of the communication system 100A shown in
The transmitting devices 111-1 to 111-3 generate optical signals to be transmitted to the Add/Drop nodes 120-1 to 120-3, respectively. The optical signals generated by the transmitting devices 111-1 to 111-3 are added to the cores 211-1, 213-1, and 215-1 of the MCF 210-1, respectively. The receiving devices 112-1 to 112-3 receive optical signals transmitted from the Add/Drop nodes 120-1 to 120-3 to the transceiving node 110a, respectively. The receiving devices 112-1 to 112-3 receive optical signals from the cores 212-1, 214-1, and 216-1 of the MCF 210-1, respectively.
The transmitting devices 111-4 to 111-6 generate optical signals to be transmitted to the Add/Drop nodes 120-1 to 120-3, respectively. The optical signals generated by the transmitting devices 111-4 to 111-6 are added to the cores 211-4, 213-4, and 215-4 of the MCF 210-4, respectively. The receiving devices 112-4 to 112-6 receive optical signals transmitted from the Add/Drop nodes 120-1 to 120-3 to the transceiving node 110b, respectively. The receiving devices 112-4 to 112-6 receive optical signals from the cores 212-4, 214-4, and 216-4 of the MCF 210-4, respectively. In the transceiving nodes 110a and 110b, a fan-in device or a fan-out device is used for adding optical signals to the MCF 200 and dropping optical signals from the MCF 200.
A connector 160-i is provided in each Add/Drop node 120-i (i=1, 2, 3). The connector 160-i is connected to the MCF 210-i and the MCF 210-(i+1). The connector 160-i drops optical signals addressed to the subject node among the optical signals added in the transceiving nodes 110a and 110b from the MCF 210-i and the MCF 210-(i+1). The connector 160-i adds an optical signal addressed to the transceiving node 110a to the cores of the MCF 210-i. The connector 160-i adds an optical signal addressed to the transceiving node 110b to the cores of the MCF 210-(i+1).
In the Add/Drop node 120-1, the connector 160-1 drops an optical signal addressed to the subject node from the core 211-1 of the MCF 210-1. The connector 160-1 connects the dropped optical signal to the transceiving device 125-1. Moreover, the connector 160-1 adds an optical signal generated by the transceiving device 125-1 to the core 212-1 of the MCF 210-1. The optical signal added to the core 212-1 is an optical signal which is transmitted from the subject node to the transceiving node 110a.
Furthermore, the connector 160-1 drops an optical signal addressed to the subject node from the core 211-2 of the MCF 210-2. The connector 160-1 connects the dropped optical signal to the transceiving device 126-1. Moreover, the connector 160-1 adds an optical signal generated by the transceiving device 126-1 to the core 212-2 of the MCF 210-2. The optical signal added to the core 212-2 is an optical signal which is transmitted from the subject node to the transceiving node 110b.
The connector 160-1 connects the cores 213-1 to 216-1 among the cores of the MCF 210-1 to the cores 213-2 to 216-2 among the cores of the MCF 210-2, respectively. The connector 160-1 relays optical signals between the MCF 210-1 and the MCF 210-2. The connector 160-1 relays optical signals transmitted through cores other than the cores 211-1, 212-1, 211-2, and 212-2 through which optical signals are added or dropped.
In the Add/Drop node 120-2, the connector 160-2 drops an optical signal addressed to the subject node from the core 213-2 of the MCF 210-2. The connector 160-2 connects the dropped optical signal to the transceiving device 125-2. Moreover, the connector 160-2 adds an optical signal generated by the transceiving device 125-2 to the core 214-2 of the MCF 210-2. The optical signal added to the core 214-2 is an optical signal which is transmitted from the subject node to the transceiving node 110a.
Furthermore, the connector 160-2 drops an optical signal addressed to the subject node from the core 213-3 of the MCF 210-3. The connector 160-2 connects the dropped optical signal to the transceiving device 126-2. Moreover, the connector 160-2 adds an optical signal generated by the transceiving device 126-2 to the core 214-3 of the MCF 210-3. The optical signal added to the core 214-3 is an optical signal which is transmitted from the subject node to the transceiving node 110b.
The connector 160-2 connects the cores 211-2, 212-2, 215-2, and 216-2 among the cores of the MCF 210-2 to the cores 211-3, 212-3, 215-3, and 216-3 among the cores of the MCF 210-3, respectively. The connector 160-2 relays optical signals between the MCF 210-2 and the MCF 210-3. The connector 160-2 relays optical signals transmitted through cores other than the cores 213-2, 214-2, 213-3, and 214-3 through which optical signals are added or dropped.
In the Add/Drop node 120-3, the connector 160-3 drops an optical signal addressed to the subject node from the core 215-3 of the MCF 210-3. The connector 160-3 connects the dropped optical signal to the transceiving device 126-3. Moreover, the connector 160-3 adds an optical signal generated by the transceiving device 126-3 to the core 216-3 of the MCF 210-3. The optical signal added to the core 216-3 is an optical signal which is transmitted from the subject node to the transceiving node 110a.
Furthermore, the connector 160-3 drops an optical signal addressed to the subject node from the core 215-4 of the MCF 210-4. The connector 160-4 connects the dropped optical signal to the transceiving device 125-3. Moreover, the connector 160-3 adds an optical signal generated by the transceiving device 125-3 to the core 216-3 of the MCF 210-4. The optical signal added to the core 216-4 is an optical signal which is transmitted from the subject node to the transceiving node 110b.
The connector 160-3 connects the cores 211-3 to 214-3 among the cores of the MCF 210-3 to the cores 211-4 to 214-4 among the cores of the MCF 210-4, respectively. The connector 160-3 relays optical signals between the MCF 210-3 and the MCF 210-4. The connector 160-3 relays optical signals transmitted through cores other than the cores 215-3, 216-3, 215-4, and 216-4 through which optical signals are added or dropped.
The connectors 160-1 to 160-3 of the second embodiment can be configured similarly to the connectors 150-1 to 150-3 of the first embodiment by using the small-diameter fiber, the optical waveguide, the optical system, and the like as shown in
In the communication system 100A of the second embodiment, a transmission communication path and a reception communication path are formed between the transceiving nodes 110a and 110b and the Add/Drop nodes 120-1 to 120-3. The transceiving nodes 110a and 110b can communicate with the Add/Drop nodes 120-1 to 120-3 individually. In this manner, the communication system 100A has a tree-type logical topology in which the transceiving nodes 110a and 110b are used as root nodes.
The Add/Drop nodes 120-1 to 120-3 may use any one of the communication paths directed to the two transceiving nodes 110a and 110b as an active system (0-system) and use the other as a standby system (1-system). Moreover, the Add/Drop nodes 120-1 to 120-3 may use a communication path of the shorter transmission distance as the 0-system and use a communication path of the longer transmission distance as the 1-system. In the Add/Drop nodes 120-1 to 120-3, since a process of dividing multiplexed optical signals having different wavelengths in respective wavelengths is not required in adding or dropping optical signals, it is possible to reduce the time and labor required for installation and maintenance of devices.
Although a case in which each MCF 210 has six cores 211 to 216 has been described, the MCF 210 may have seven or more cores. When the MCF 210 has seven or more cores, optical signals may be added and dropped for two or more cores of the Add/Drop node 120.
Moreover, WDM transmission may be performed in each core of the MCF 210. When WDM transmission is performed, as shown in
Moreover, the transceiving node 110a and the transceiving node 110b may be connected together using the MCF 210 or a MCF having seven or more cores. In the communication system 100A, when the roles of the transceiving nodes 110a and 110b and the Add/Drop nodes 120-1 to 120-3 are changed, a logical topology can be easily changed by attaching a connector to the transceiving nodes 110a and 110b and replacing the connector 150 of each of the Add/Drop nodes 120-1 to 120-3 with another connector. In this way, it is possible to flexibly cope with a change in the network configuration.
The transceiving node 110 and the Add/Drop node 120-1 are connected together by the MCF 220-1. The Add/Drop node 120-1 and the Add/Drop node 120-2 are connected together by the MCF 220-2. The Add/Drop node 120-2 and the Add/Drop node 120-3 are connected by the MCF 220-3. The Add/Drop node 120-3 and the transceiving node 110 are connected together by the MCF 220-4.
The MCFs 220-1 to 220-4 each have fourth cores 221 to 224 unlike the MCFs 200-1 to 200-4 of the first embodiment. In the Add/Drop node 120 of the communication systems of the first and second embodiments, optical signals are added or dropped to or from the core at the same position in the MCF. In contrast, in the Add/Drop node 120 of the communication system 100B of the third embodiment, the position of a core in which an optical signal is dropped in the MCF is different from the position of a core in which an optical signal is added in the MCF.
Each node of the communication system 100B includes a transmitting device and a receiving device that perform communication between nodes similarly to the communication system 100 (
A connector 170 is provided in each Add/Drop node 120. A connector 170-i of an Add/Drop node 120-i (i=1, 2, . . . , n) connects together an MCF 220-i and an MCF 220-(i+1). The connector 170-i drops an optical signal addressed to the subject node among optical signals added to the core of the MCF 220-1 at the transceiving node 110 from the MCF 200-i. Moreover, the connector 170-i adds an optical signal addressed to the transceiving node 110 to the core of the MCF 200-(i+1).
In the Add/Drop node 120-1, the connector 170-1 drops an optical signal addressed to the subject node from the core 221-1 of the MCF 220-1. The connector 170-1 connects the dropped optical signal to the receiving device 122-1. Moreover, the connector 170-1 adds an optical signal generated by the transmitting device 121-1 to the core 224-2 of the MCF 220-2. The optical signal added to the core 224-2 is an optical signal transmitted from the Add/Drop node 120-1 to the transceiving node 110. The core 224-1 is not used in the MCF 220-1 that connects together the transceiving node 110 and the Add/Drop node 120-1.
The connector 170-1 connects the cores 222-1 and 223-1 among the cores of the MCF 220-1 to the cores 222-2 and 223-2 among the cores of the MCF 220-2, respectively. The connector 170-1 relays optical signals between the MCF 220-1 and the MCF 220-2. The connector 150-1 relays optical signals transmitted through cores other than the cores 221-1 and 224-2 through which optical signals are added or dropped and non-used cores 224-1 and 221-2.
In the Add/Drop node 120-2, the connector 170-2 drops an optical signal addressed to the subject node from the core 222-2 of the MCF 220-2. The connector 170-2 connects the dropped optical signal to the receiving device 122-2. Moreover, the connector 170-2 adds an optical signal generated by the transmitting device 121-2 to the core 221-3 of the MCF 220-3. The optical signal added to the core 221-3 is an optical signal transmitted from the Add/Drop node 120-2 to the transceiving node 110.
The connector 170-2 connects the cores 223-2 and 224-2 among the cores of the MCF 220-2 to the cores 223-3 and 224-3 among the cores of the MCF 220-2, respectively. The connector 170-2 relays optical signals between the MCF 220-2 and the MCF 220-3. The connector 150-2 relays optical signals transmitted through cores other than the cores 222-2 and 221-3 through which an optical signal is added or dropped and the non-used cores 221-2 and 222-3.
In the Add/Drop node 120-3, the connector 170-3 drops an optical signal addressed to the subject node from the core 223-3 of the MCF 220-3. The connector 170-3 connects the dropped optical signal to the receiving device 122-3. Moreover, the connector 170-3 adds the optical signal generated by the transmitting device 121-3 to the core 222-4 of the MCF 220-4. The optical signal added to the core 222-4 is an optical signal transmitted from the Add/Drop node 120-3 to the transceiving node 110.
The connector 170-3 connects the cores 221-3 and 224-3 among the cores of the MCF 220-3 to the cores 221-4 and 224-4 among the cores of the MCF 220-4, respectively. The connector 170-3 relays optical signals between the MCF 220-3 and the MCF 220-4. The connector 170-3 relays optical signals transmitted through cores other than the cores 223-3 and 222-4 through which optical signals are added or dropped and the non-used cores 222-3 and 223-4.
The connectors 170-1 to 170-3 of the third embodiment can be configured similarly to the connectors 150-1 to 150-3 of the first embodiment by using the small-diameter fiber, the optical waveguide, the optical system, and the like as shown in
Although a case in which the MCF 220 includes four cores has been described, the MCF 220 may include five or more cores. When the MCF 220 includes five or more cores, optical signals may be added or dropped to or from two or more cores in the Add/Drop node 120. Moreover, the number of non-used cores between nodes may be increased so that a core in which the number of adjacent non-used cores is large may be preferentially allocated to an optical signal of which the transmission distance is long.
Moreover, WDM transmission may be performed in each core of the MCF 220. When WDM transmission is performed, as shown in
Even when WDM transmission is performed, the optical signals of the cores 223-2 and 224-2 of the MCF 220-2 that are not the Add/Drop target are relayed to the cores 223-3 and 224-3 of the MCF 220-3. The other Add/Drop nodes 120 have a configuration similar to that of the Add/Drop node 120-2.
In the third embodiment, a configuration in which the positions of Add/Drop target cores in the Add/Drop node 120 are different (also referred to as a “different core facing configuration”) has been described, this configuration may be used in combination with a configuration in which the positions of Add/Drop target cores are the same (also referred to as a “same core facing configuration”) as in the first embodiment. When the amount of information transmitted from the transceiving node 110 to the Add/Drop node 120 is different from the amount of information transmitted from the Add/Drop node 120 to the transceiving node 110, the number of optical signals dropped from the MCF 220 in the Add/Drop node 120 may be different from the number of optical signals added to the MCF 220.
The communication system 100A of the second embodiment having a physical topology of a dual-system one-way ring configuration may have a configuration in which the positions of Add/Drop target cores in the Add/Drop node 120 are different (a different core facing configuration) similarly to the communication system 100B of the third embodiment. When the communication system 100A has a different core facing configuration, a core in which the number of adjacent cores is small or a core in which the number of cores through which optical signals are transmitted is small among the adjacent cores may be preferentially allocated to optical signals of which the transmission distance is long.
Each node of the communication system 100C includes a transceiving device (Tx/Rx) that performs communication between nodes. Transceiving devices 113-1 to 113-3 are provided in the transceiving node 110. Transceiving devices 125-1 to 125-3 are provided in the Add/Drop nodes 120-1 to 120-3, respectively. The transceiving devices 113-1 to 113-3 generate optical signals to be transmitted to the Add/Drop nodes 120-1 to 120-3, respectively. Moreover, the transceiving devices 113-1 to 113-3 receive optical signals transmitted from the Add/Drop nodes 120-1 to 120-3, respectively, and acquire information included in the optical signals. The transceiving devices 125-1 to 125-3 generate optical signals to be transmitted to the transceiving node 110. Moreover, the transceiving devices 125-1 to 125-3 receive optical signals transmitted from the transceiving node 110 and acquire information included in the optical signals.
The transceiving devices 113-1 to 113-3 generate optical signals to be transmitted to the Add/Drop nodes 120-1 to 120-3, respectively. Three optical signals generated by the transceiving devices 113-1 to 113-3 are added to the cores 201-1 to 203-1 of the MCF 200-1, respectively. Moreover, the transceiving devices 113-1 to 113-3 receive optical signals from the Add/Drop nodes 120-1 to 120-3 via the cores 201-1 to 203-1 of the MCF 200-1, respectively. A fan-in device or a fan-out device is used for adding optical signals to the MCF 200-1 and dropping optical signals from the MCF 200-1.
A connector 180-i is provided in each Add/Drop node 120-i (i=1, 2, 3). The connector 180-i is connected to the MCF 200-i and the MCF 200-(i+1). The connector 180-i drops an optical signal from the core 20i-i of the MCF 200-i and connects the dropped optical signal to the transceiving device 125-i. Moreover, the connector 180-i adds an optical signal generated by the transceiving device 125-i to the core 20i-i of the MCF 200-i. The optical signal generated by the transceiving device 125-i is an optical signal transmitted from the Add/Drop node 120-i to the transceiving node 110. The connector 180-i connects together the cores 20i-i and 20i-(i+1) other than the Add/Drop target cores among the cores of the MCF 200-i and the cores of the MCF 200-(i+1) to relay optical signals.
The transceiving node 110 and the Add/Drop node 120-1 perform two-way communication using a communication path formed by the core 201-1. The transceiving node 110 and the Add/Drop node 120-2 perform two-way communication using a communication path formed by the cores 202-1 and 202-2. The transceiving node 110 and the Add/Drop node 120-3 perform two-way communication using a communication path formed by the cores 203-1, 203-2, and 203-3. The core 201-2 of the MCF 200-2, the cores 201-3 and 202-3 of the MCF 200-3, and the cores 201-4 to 203-4 of the MCF 200-4 are cores which are not used in communication.
In the communication system 100C, the Add/Drop node 120-3 may perform communication with the transceiving node 110 using the core 201-4 of the MCF 200-4 to shorten a communication path. In this case, a fan-in device or a fan-out device is necessary in a connecting portion with the MCF 200-4 in the transceiving node 110.
Moreover, in the communication system 100C, WDM transmission may be performed between the transceiving node 110 and each of the Add/Drop nodes 120-1 to 120-3. When WDM transmission is performed as shown in
An optical signal dropped from the core 201-1 of the MCF 200-1 in the connector 180-1 is connected to the optical circulator 127-1. The optical signal connected from the connector 180-1 to the optical circulator 127-1 is output to the splitter 124-1. The splitter 124-1 splits the input optical signal in respective wavelengths and outputs the optical signals obtained by splitting to the receiving device 122-1. Optical signals having different wavelengths generated by the plurality of transmitting devices 121-1 are input to the combiner 123-1. The combiner 123-1 combines the input optical signals and outputs the optical signal obtained by combining to the optical circulator 127-1. The optical signal input from the combiner 123-1 to the optical circulator 127-1 is output to the connector 180-1. The connector 180-1 adds the optical signal from the optical circulator 127-1 to the core 201-1 of the MCF 200-1 whereby an optical signal addressed to the transceiving node 110 is added to the MCF 200-1.
Even when WDM transmission is performed, the optical signals of the cores 202-1 and 203-1 of the MCF 200-1, which are not the Add/Drop target, are relayed to the cores 202-2 and 203-2 of the MCF 200-2. The other Add/Drop nodes 120 have a configuration similar to that of the Add/Drop node 120-1.
Although a case in which one core is the Add/Drop target in each of the Add/Drop nodes 120 has been described in the fourth embodiment, optical signals may be dropped from a plurality of cores in each of the Add/Drop nodes 120 and optical signals may be added to a plurality of cores.
When a transceiving device in which the transmitting device 121-1 and the receiving device 122-1 are integrated is used (that is, when the transceiving device has an optical circulator therein), it is not necessary to have the optical circulator 127-1. Since it is not necessary to provide two optical components of a transmission-side combiner and a reception-side splitter, it is possible to reduce the number of optical components in each Add/Drop node 120. Examples of an optical component used for combining and splitting include an array wavelength grating (AWG; a wavelength combining and splitting element).
When there are many optical signals of different wavelengths to be multiplexed when WDM transmission is performed, a plurality of stages of combiners/splitters may be combined.
Since optical signals are added or dropped in respective cores in the Add/Drop node 120, signal deterioration such as signal constriction can be avoided as compared to when optical signals are added or dropped in respective wavelengths. Due to this, even when splitting and combining are performed in multiple stages as shown in
Each node of the communication system 100D includes a transceiving device (Tx/Rx) that performs communication between nodes. Transceiving devices 113-1 to 113-3 are provided in the transceiving node 110a. Transceiving devices 113-4 to 113-6 are provided in the transceiving node 110b. Transceiving devices 125-1 to 125-3 and 126-1 to 126-3 are provided in the Add/Drop nodes 120-1 to 120-3, respectively. The transceiving devices 113-1 to 113-6 generate optical signals to be transmitted to the Add/Drop nodes 120-1 to 120-3, respectively. The transceiving devices 125-1 to 125-3 generate optical signals to be transmitted to the transceiving node 110a. The transceiving devices 126-1 to 126-3 generate optical signals to be transmitted to the transceiving node 110b. Moreover, the transceiving devices 113-1 to 113-6 receive optical signals transmitted from the Add/Drop nodes 120-1 to 120-3, respectively, and acquire information included in the optical signals. The transceiving devices 125-1 to 125-3 receive optical signals transmitted from the transceiving node 110a and acquire information included in the optical signals. The transceiving devices 126-1 to 126-3 receive optical signals transmitted from the transceiving node 110b and acquire information included in the optical signals.
In the transceiving node 110a, the transceiving devices 113-1 to 113-3 generate optical signals to be transmitted to the Add/Drop nodes 120-1 to 120-3, respectively. Three optical signals generated by the transceiving devices 113-1 to 113-3 are added to the cores 201-1 to 203-1 of the MCF 200-1, respectively. Moreover, the transceiving devices 113-1 to 113-3 receive optical signals from the Add/Drop nodes 120-1 to 120-3 via the cores 201-1 to 203-1 of the MCF 200-1, respectively. A fan-in device or a fan-out device is used for adding optical signals to the MCF 200-1 and dropping optical signals from the MCF 200-1.
In the transceiving node 110b, the transceiving devices 113-4 to 113-6 generate optical signals to be transmitted to the Add/Drop nodes 120-1 to 120-3, respectively. Three optical signals generated by the transceiving devices 113-4 to 113-6 are added to the cores 201-4 to 203-4 of the MCF 200-4, respectively. Moreover, the transceiving devices 113-4 to 113-6 receive optical signals from the Add/Drop nodes 120-1 to 120-3 via the cores 201-4 to 203-4 of the MCF 200-4, respectively. A fan-in device or a fan-out device is used for adding optical signals to the MCF 200-4 and dropping optical signals from the MCF 200-4 similarly to the transceiving node 110a.
A connector 185-i is provided in each Add/Drop node 120-i (i=1, 2, 3). The connector 185-i is connected to the MCF 200-i and the MCF 200-(i+1). The connector 185-i drops an optical signal from the core 20i-i of the MCF 200-i and connects to the dropped optical signal to the transceiving device 125-i. The connector 185-i adds an optical signal generated by the transceiving device 125-i to the core 20i-i of the MCF 200-i. The optical signal generated by the transceiving device 125-i is an optical signal which is transmitted from the Add/Drop node 120-i to the transceiving node 110a.
Moreover, the connector 185-i drops an optical signal from the core 20i-(i+1) of the MCF 200-(i+1) and connects the dropped optical signal to the transceiving device 126-i. The connector 185-i adds an optical signal generated by the transceiving device 126-i to the core 20i-(i+1) of the MCF 200-(i+1). The optical signal generated by the transceiving device 126-i is an optical signal which is transmitted from the Add/Drop node 120-i to the transceiving node 110b.
Moreover, the connector 185-i connects together the core 20i-i and the core 20i-(i+1) other than the cores which are the Add/Drop target among the cores of the MCF 200-i and the cores of the MCF 200-(i+1) to relay optical signals.
The transceiving node 110a and the Add/Drop node 120-1 perform two-way communication using a communication path formed by the core 201-1. The transceiving node 110a and the Add/Drop node 120-2 perform two-way communication using a communication path formed by the cores 202-1 and 202-2. The transceiving node 110a and the Add/Drop node 120-3 perform two-way communication using a communication path formed by the cores 203-1, 203-2, and 203-3.
The transceiving node 110b and the Add/Drop node 120-1 perform two-way communication using a communication path formed by the cores 201-4, 201-3, and 201-2. The transceiving node 110b and the Add/Drop node 120-2 perform two-way communication using a communication path formed by the cores 202-4 and 202-3. The transceiving node 110b and the Add/Drop node 120-3 perform two-way communication using a communication path formed by the core 203-4.
In this manner, the communication system 100D has a tree-type logical topology in which the transceiving nodes 110a and 110b are used as root nodes and can communicate with each of the Add/Drop nodes 120-1 to 120-3. In the communication system 100D, each of the Add/Drop nodes 120-1 to 120-3 can communicate with the transceiving nodes 110a and 110b. The Add/Drop nodes 120-1 to 120-3 may use any one of the communication paths directed to the two transceiving nodes 110a and 110b as an active system (0-system) and use the other as a standby system (1-system). Moreover, the Add/Drop nodes 120-1 to 120-3 may use a communication path of the shorter transmission path as the 0-system and use a communication path of the longer transmission path as the 1-system.
In the communication system 100D, the transceiving node 110a and the transceiving node 110b may be connected together using the MCF 200 or an MCF having four or more cores. In the communication system 100D, when the roles of the transceiving nodes 110a and 110b and the Add/Drop nodes 120-1 to 120-3 are changed, a logical topology can be easily changed by attaching a connector to the transceiving nodes 110a and 110b and replacing the connector 185 of each of the Add/Drop nodes 120-1 to 120-3 with another connector. In this way, it is possible to flexibly cope with a change in the network configuration.
In the first to fifth embodiments, a communication system which has a physical topology of a ring configuration and has a tree-type logical topology in which a transceiving node is used as a root node has been described. A communication system having another physical topology or another logical topology will be described.
Nodes are connected together by MCFs 200-1 to 200-4. The Add/Drop node 120-1 and the Add/Drop node 120-2 are connected together by the MCF 200-2. The Add/Drop node 120-2 and the Add/Drop node 120-3 are connected together by the MCF 200-3. The Add/Drop node 120-3 and the Add/Drop node 120-4 are connected together by the MCF 200-4. The Add/Drop node 120-4 and the Add/Drop node 120-1 are connected together by the MCF 200-1. The MCFs 200-1 to 200-4 connecting the nodes each have three cores 201, 202, and 203.
Three transceiving devices (Tx/Rx) 125-i for communicating with other Add/Drop nodes 120 and a connector 190-i are provided in each Add/Drop node 120-i (i=1, 2, 3, 4). The transceiving device 125-i is provided so as to correspond to a communication counterpart Add/Drop node 120. The connector 190-1 is connected to the MCF 200-1 and the MCF 200-2. The connector 190-2 is connected to the MCF 200-2 and the MCF 200-3. The connector 190-3 is connected to the MCF 200-3 and the MCF 200-4. The connector 190-4 is connected to the MCF 200-4 and the MCF 200-1.
In the Add/Drop node 120-1, the connector 190-1 drops an optical signal from the core 201-1 of the MCF 200-1 and connects the dropped optical signal to the transceiving device 125-1 that communicates with the Add/Drop node 120-4. The connector 190-1 adds an optical signal generated by the transceiving device 125-1 that communicates with the Add/Drop node 120-4 to the core 201-1 of the MCF 200-1. Moreover, the connector 190-1 drops an optical signal from the core 202-2 of the MCF 200-2 and connects the dropped optical signal to the transceiving device 125-1 that communicates with the Add/Drop node 120-3. The connector 190-1 adds an optical signal generated by the transceiving device 125-1 that communicates with the Add/Drop node 120-3 to the core 202-2 of the MCF 200-2. Moreover, the connector 190-1 drops an optical signal from the core 201-2 of the MCF 200-2 and connects the dropped optical signal to the transceiving device 125-1 that communicates with the Add/Drop node 120-2. The connector 190-1 adds an optical signal generated by the transceiving device 125-1 that communicates with the Add/Drop node 120-2 to the core 201-2 of the MCF 200-2.
In the Add/Drop node 120-2, similarly to the connector 190-1, the connector 190-2 adds and drops optical signals to and from the core 201-2 of the MCF 200-2 and the cores 201-3 and 202-3 of the MCF 200-3. The connector 190-2 connects the dropped optical signals to the transceiving devices 125-2 that communicate with the Add/Drop nodes 120-1, 120-3, and 120-4. Moreover, the connector 190-2 adds optical signals generated by the transceiving devices 125-2 that communicate with the Add/Drop nodes 120-1, 120-3, and 120-4 to the core 201-2 of the MCF 200-2 and the cores 201-3 and 202-3 of the MCFs 200-3. The connector 190-2 relays optical signals between the core 202-2 of the MCF 200-2 and the core 202-3 of the MCF 200-3.
In the Add/Drop node 120-3, similarly to the connector 190-1, the connector 190-3 adds and drops optical signals to and from the cores 201-3 and 202-3 of the MCF 200-3 and the core 202-4 of the MCF 200-4. The connector 190-3 connects the dropped optical signals to the transceiving devices 125-3 that communicate with the Add/Drop nodes 120-1, 120-2, and 120-4. Moreover, the connector 190-3 adds optical signals generated by the transceiving devices 125-3 that communicate with the Add/Drop nodes 120-2, 120-1, and 120-4 to the cores 201-3 and 202-3 of the MCF 200-3 and the core 202-4 of the MCF 200-4. The connector 190-3 relays optical signals between the core 203-3 of the MCF 200-3 and the core 203-4 of the MCF 200-4.
In the Add/Drop node 120-4, similarly to the connector 190-1, the connector 190-4 adds and drops optical signals to and from the cores 202-4 and 203-4 of the MCF 200-4 and the core 201-1 of the MCF 200-1. The connector 190-4 connects the dropped optical signals to the transceiving devices 125-4 that communicate with the Add/Drop nodes 120-3, 120-2, and 120-1. Moreover, the connector 190-4 adds optical signals generated by the transceiving devices 125-4 that communicate with the Add/Drop nodes 120-3, 120-2, and 120-1 to the core 201-1 of the MCF 200-1 and the cores 201-4 and 202-4 of the MCF 200-4.
When the MCFs 200-1 to 200-4 are connected together as described above using the connectors 190-1 to 190-4, one-to-one communication paths are formed between the Add/Drop nodes 120-1 to 120-4. The communication system 100E has a perfect mesh-type logical topology.
In the communication system 100E, a configuration in which a communication path is formed between each of two nodes of the Add/Drop nodes 120-1 to 120-4 has been described. However, the communication system may have a partial mesh-type logical topology in which a communication path is formed between some of the Add/Drop nodes 120-1 to 120-4. Moreover, in the communication system 100E, a configuration of two-way communication in which optical signals of which the transmission directions are different are transmitted through one core has been described. However, the communication system may perform one-way communication in which an optical signal of one transmission direction is transmitted through one core as shown in
Each node of the communication system 300 includes a transmitting device (Tx) and a receiving device (Rx) that perform communication between nodes. Transmitting devices 111-1 to 111-3 and receiving devices 112-1 to 112-3 are provided in the transceiving node 110. A transmitting device 121-1 and a receiving device 122-1 are provided in the Add/Drop node 120-1. A transmitting device 121-2 and a receiving device 122-2 are provided in the Add/Drop node 120-2. A transmitting device 121-3 and a receiving device 122-3 are provided in the Add/Drop node 120-3.
A connector 330 is provided in the transceiving node 110. The connector 330 connects together the MCF 220-2 and the MCF 220-3. The connector 330 adds optical signals generated by the transmitting devices 111-1 to 111-3 to the cores 221-2 and 222-3 of the MCF 220-2 and the core 224-3 of the MCF 220-3, respectively. Moreover, the connector 330 connects the optical signals dropped from the cores 222-2 and 224-2 of the MCF 220-2 and the core 223-3 of the MCF 220-3 to the receiving devices 112-1 to 112-3, respectively.
Connectors 340-1 to 340-3 are provided in the Add/Drop nodes 120-1 to 120-3, respectively. Each of the connectors 340-1 to 340-3 drops an optical signal addressed to the subject node from the core of the MCF 220 and adds an optical signal addressed to the transceiving node 110 to the core of the MCF 220.
In the Add/Drop node 120-1, the connector 340-1 is connected to the MCF 220-1. The connector 340-1 drops an optical signal addressed to the subject node from the core 221-1 of the MCF 220-1 and connects the dropped optical signal to the receiving device 122-1. Moreover, the connector 340-1 adds an optical signal generated by the transmitting device 121-1 to the core 222-1 of the MCF 220-1.
In the Add/Drop node 120-2, the connector 340-2 is connected to the MCF 220-1 and the MCF 220-2. The connector 340-2 drops an optical signal addressed to the subject node from the core 223-2 of the MCF 220-2 and connects the dropped optical signal to the receiving device 122-2. Moreover, the connector 340-2 adds an optical signal generated by the transmitting device 121-2 to the core 224-2 of the MCF 220-2. The connector 340-2 connects the cores 221-1 and 222-1 of the MCF 220-1 to the cores 221-2 and 222-2 of the MCF 220-2. The connector 340-2 relays optical signals between the MCF 220-1 and the MCF 220-2.
In the Add/Drop node 120-3, the connector 340-3 is connected to the MCF 220-3. The connector 340-3 drops an optical signal addressed to the subject node from the core 224-3 of the MCF 220-3 and connects the dropped optical signal to the receiving device 122-3. Moreover, the connector 340-3 adds an optical signal generated by the transmitting device 121-3 to the core 223-3 of the MCF 220-3.
In the communication system 300 of the seventh embodiment, a transmission communication path and a reception communication path are formed between the transceiving node 110 and each of the Add/Drop nodes 120-1 to 120-3. The transceiving node 110 can communicate with the individual Add/Drop nodes 120-1 to 120-3. In this manner, the communication system 300 has a tree-type logical topology in which the transceiving node 110 is used as a root node. In
Since the multi-core fiber (MCF) is applied to the communication system having a linear physical topology, when a number of devices requiring high-speed communication such as a datacenter, for example, are connected together, it is possible to configure a system with a small number of connections as compared to a single-core fiber (SCF) and to reduce the time and labor in changing or maintaining the system. Moreover, since the cross-sectional area of a cable per core can be reduced by using MCF instead of SCF, it is possible to decrease the volume occupied by a connection cable remarkably.
In the seventh embodiment, a configuration in which the cores in each node are divided into a transmission core and a reception core has been described. However, like the communication system 100C of the fourth embodiment, a transmission core and a reception core in each node may be the same cores. Moreover, when a core which is not used for signal transmission is present among the cores of the MCF that connects together nodes, optical signals may be added or dropped to or from two or more cores of the Add/Drop nodes 120-1 to 120-3.
Nodes are connected together by MCFs 210-1 to 210-4. The transceiving node 110a and the Add/Drop node 120-1 are connected together by the MCF 210-1. The transceiving node 110a and the Add/Drop node 120-2 are connected together by the MCF 210-2. The Add/Drop node 120-2 and the transceiving node 110b are connected together by the MCF 210-3. The transceiving node 110b and the Add/Drop node 120-3 are connected together by the MCF 210-4. The MCFs 210-1 to 210-4 that connect nodes each include six cores 211 to 216. Each node of the communication system 300A includes transceiving devices (Tx/Rx) that perform communication between nodes and a connector that connects the MCFs 210.
The Add/Drop node 120-1 includes a connector 360-1 and transceiving devices 125-1 and 126-1. The connector 360-1 is connected to the MCF 210-1. The connector 360-1 drops an optical signal from the core 216-1 of the MCF 210-1 and connects the dropped optical signal to the transceiving device 125-1. The connector 360-1 adds an optical signal generated by the transceiving device 125-1 to the core 215-1 of the MCF 210-1.
The connector 360-1 drops an optical signal from the core 212-1 of the MCF 210-1 and connects the dropped optical signal to the transceiving device 126-1. The connector 360-1 adds the optical signal generated by the transceiving device 126-1 to the core 211-1 of the MCF 210-1. The Add/Drop node 120-1 performs communication with the transceiving node 110a using the transceiving device 125-1. Moreover, the Add/Drop node 120-1 performs communication with the transceiving node 110b using the transceiving device 126-1.
The transceiving node 110a includes a connector 350-1 and transceiving devices 113-1 to 113-3. The connector 350-1 is connected to the MCF 210-1 and the MCF 210-2. The connector 350-1 drops an optical signal from the core 215-1 of the MCF 210-1 and connects the dropped optical signal to the transceiving device 113-1. The connector 350-1 adds the optical signal generated by the transceiving device 113-1 to the core 216-1 of the MCF 210-1. The connector 350-1 drops an optical signal from the core 216-2 of the MCF 210-2 and connects the dropped optical signal to the transceiving device 113-2. The connector 350-1 adds the optical signal generated by the transceiving device 113-2 to the core 215-2 of the MCF 210-2.
The connector 350-1 drops an optical signal from the core 214-2 of the MCF 210-2 and connects the dropped optical signal to the transceiving device 113-3. The connector 350-1 adds the optical signal generated by the transceiving device 113-3 to the core 213-2 of the MCF 210-2. The connector 350-1 connects the cores 211-1 and 212-1 of the MCF 210-1 to the cores 211-2 and 212-2 of the MCF 210-2, respectively. The connector 350-1 relays optical signals between the MCF 210-1 and the MCF 210-2. The transceiving node 110a performs communication with the Add/Drop nodes 120-1 to 120-3 using the transceiving devices 113-1 to 113-3, respectively.
The Add/Drop node 120-2 includes a connector 360-2 and transceiving devices 125-2 and 126-2. The connector 360-2 is connected to the MCF 210-2 and the MCF 210-3. The connector 360-2 drops an optical signal from the core 215-2 of the MCF 210-2 and connects the dropped optical signal to the transceiving device 126-2. The connector 360-2 adds the optical signal generated by the transceiving device 126-2 to the core 216-2 of the MCF 210-2.
The connector 360-2 drops an optical signal from the core 216-3 of the MCF 210-3 and connects the dropped optical signal to the transceiving device 125-2. The connector 360-2 adds the optical signal generated by the transceiving device 125-2 to the core 215-3 of the MCF 210-3. The connector 360-2 connects the cores 211-2 to 214-2 of the MCF 210-2 to the cores 211-3 to 214-3 of the MCF 210-3, respectively. The connector 360-2 relays optical signals between the MCF 210-2 and the MCF 210-3. The Add/Drop node 120-2 performs communication with the transceiving node 110a using the transceiving device 126-2. Moreover, the Add/Drop node 120-2 performs communication with the transceiving node 110b using the transceiving device 125-2.
The transceiving node 110b includes a connector 350-2 and transceiving devices 113-4 to 113-6. The connector 350-2 is connected to the MCF 210-3 and the MCF 210-4. The connector 350-2 drops an optical signal from the core 211-3 of the MCF 210-3 and connects the dropped optical signal to the transceiving device 113-4. The connector 350-2 adds the optical signal generated by the transceiving device 113-4 to the core 212-3 of the MCF 210-3. The connector 350-2 drops an optical signal from the core 215-3 of the MCF 210-3 and connects the dropped optical signal to the transceiving device 113-5. The connector 350-2 adds the optical signal generated by the transceiving device 113-5 to the core 216-3 of the MCF 210-3.
Moreover, the connector 350-2 drops an optical signal from the core 216-4 of the MCF 210-4 and connects the dropped optical signal to the transceiving device 113-6. The connector 350-2 adds the optical signal generated by the transceiving device 113-6 to the core 215-4 of the MCF 210-4. The connector 350-2 connects the cores 213-3 and 214-3 of the MCF 210-3 to the cores 213-4 and 214-4 of the MCF 210-4, respectively. The connector 350-2 relays optical signals between the MCF 210-3 and the MCF 210-4. The transceiving node 110b performs communication with the Add/Drop nodes 120-1 to 120-3 using the transceiving devices 113-4 to 113-6, respectively.
The Add/Drop node 120-3 includes a connector 360-3 and transceiving devices 125-3 and 126-3. The connector 360-3 is connected to the MCF 210-4. The connector 360-3 drops an optical signal from the core 215-4 of the MCF 210-4 and connects the dropped optical signal to the transceiving device 125-3. The connector 360-3 adds the optical signal generated by the transceiving device 125-3 to the core 216-4 of the MCF 210-4.
The connector 360-3 drops an optical signal from the core 213-4 of the MCF 210-4 and connects the dropped optical signal to the transceiving device 126-3. The connector 360-3 adds the optical signal generated by the transceiving device 126-3 to the core 214-4 of the MCF 210-4. The Add/Drop node 120-3 performs communication with the transceiving node 110b using the transceiving device 125-3. Moreover, the Add/Drop node 120-3 performs communication with the transceiving node 110a using the transceiving device 126-3.
When the MCFs 210-1 to 210-4 are connected together using the connectors 350-1, 350-2, and 360-1 to 360-3 as described above, communication paths are formed between the transceiving nodes 110a and 110b and each of the Add/Drop nodes 120-1 to 120-3. In this manner, the communication system 300A has a tree-type logical topology in which the transceiving nodes 110a and 100b are used as root nodes and can communicate with each of the Add/Drop nodes 120-1 to 120-3.
In the communication system 300A of the eighth embodiment, the Add/Drop nodes 120-1 to 120-3 each can communicate with the transceiving nodes 110a and 110b. The Add/Drop nodes 120-1 to 120-3 may use any one of the communication paths between the two transceiving nodes 110a and 110b as an active system (0-system) and use the other as a standby system (1-system). Moreover, the Add/Drop nodes 120-1 to 120-3 may use a communication path of the shorter transmission path as the 0-system and use a communication path of the longer transmission path as the 1-system.
In the eighth embodiment, a configuration in which the cores in each node are divided into a transmission core and a reception core has been described. However, like the communication system 100C of the fourth embodiment, a transmission core and a reception core in each node may be the same cores and two-way communication may be performed in one core. Moreover, when a core which is not used for signal transmission is present among the cores of the MCF that connects nodes, optical signals may be added or dropped to or from two or more cores of the Add/Drop nodes 120-1 to 120-3.
Nodes are connected together by MCFs 230-1 to 230-3. The Add/Drop node 120-1 and the Add/Drop node 120-2 are connected together by the MCF 230-1. The Add/Drop node 120-2 and the Add/Drop node 120-3 are connected together by the MCF 230-2. The Add/Drop node 120-3 and the Add/Drop node 120-4 are connected together by the MCF 230-3. The MCFs 230 to 230-3 that connect nodes each include eight cores 231 to 238.
Three transceiving devices (Tx/Rx) 125-i for communicating with the other Add/Drop nodes 120 and a connector 370-i are provided in each Add/Drop node 120-i (i=1, 2, 3, 4). The transceiving device 125-i is provided so as to correspond to a communication counterpart Add/Drop node 120. The connector 370-1 is connected to the MCF 230-1. The connector 370-2 is connected to the MCF 230-1 and the MCF 230-2. The connector 370-3 is connected to the MCF 230-2 and the MCF 230-3. The connector 370-4 is connected to the MCF 230-3.
In the Add/Drop node 120-1, the connector 370-1 drops an optical signal from the core 232-1 of the MCF 230-1 and connects the dropped optical signal to the transceiving device 125-1 that communicates with the Add/Drop node 120-4. The connector 370-1 adds an optical signal generated by the transceiving device 125-1 that communicates with the Add/Drop node 120-4 to the core 231-1 of the MCF 230-1. Moreover, the connector 370-1 drops an optical signal from the core 236-1 of the MCF 230-1 and connects the dropped optical signal to the transceiving device 125-1 that communicates with the Add/Drop node 120-3. The connector 370-1 adds the optical signal generated by the transceiving device 125-1 that communicates with the Add/Drop node 120-3 to the core 235-1 of the MCF 230-1.
The connector 370-1 drops an optical signal from the core 238-1 of the MCF 230-1 and connects the dropped optical signal to the transceiving device 125-1 that communicates with the Add/Drop node 120-2. The connector 370-1 adds the optical signal generated by the transceiving device 125-1 that communicates with the Add/Drop node 120-2 to the core 237-1 of the MCF 230-1.
In the Add/Drop node 120-2, similarly to the connector 370-1, the connector 370-2 drops optical signals from the core 237-1 of the MCF 230-1 and the cores 233-2 and 238-2 of the MCF 230-2. The connector 370-2 connects the dropped optical signals to the transceiving devices 125-2 that communicate with the Add/Drop nodes 120-1, 120-3, and 120-4. Moreover, the connector 370-2 adds the optical signals generated by the transceiving devices 125-2 that communicate with the Add/Drop nodes 120 to the core 238-1 of the MCF 230-1 and the cores 234-2 and 237-2 of the MCF 230-2, respectively. The connector 370-2 relays optical signals between the cores 231-1 and 232-1 of the MCF 230-1 and the cores 231-2 and 232-2 of the MCF 230-2.
In the Add/Drop node 120-3, similarly to the connector 370-1, the connector 370-3 drops optical signals from the cores 237-2 and 235-2 of the MCF 230-2 and the core 238-3 of the MCF 230-3. The connector 370-2 connects the dropped optical signals to the transceiving devices 125-3 that communicate with the Add/Drop nodes 120-1, 120-2, and 120-4. Moreover, the connector 370-3 adds the optical signals generated by the transceiving devices 125-3 that communicate with the Add/Drop nodes 120 to the cores 236-2 and 238-2 of the MCF 230-2 and the core 237-3 of the MCF 230-3, respectively. The connector 370-3 relays optical signals between the cores 231-2 to 234-2 of the MCF 230-2 and the cores 231-3 to 234-3 of the MCF 230-3.
In the Add/Drop node 120-4, similarly to the connector 370-1, the connector 370-4 drops optical signals from the cores 231-1, 233-3, and 237-4 of the MCF 230-3. The connector 370-4 connects the dropped optical signals to the transceiving devices 125-4 that communicate with the Add/Drop nodes 120-1, 120-2, and 120-3. Moreover, the connector 370-4 adds the optical signals generated by the transceiving devices 125-4 that communicate with the Add/Drop nodes 120 to the cores 232-3, 234-3, and 238-3 of the MCF 230-3, respectively.
When the MCFs 230-1 to 230-3 are connected together using the connectors 370-1 to 370-4 as described above, one-to-one communication paths are formed between each of two nodes of the Add/Drop nodes 120-1 to 120-4. The communication system 300B has a perfect mesh-type logical topology. The cores 233-1 and 234-1 of the MCF 230-1 and the cores 235-3 and 236-3 of the MCF 230-3 are cores which are not used for communication.
In the ninth embodiment, a configuration in which a communication path is formed between each of two nodes of the Add/Drop nodes 120-1 to 120-4 has been described. However, the communication system may have a partial mesh-type logical topology in which a communication path is formed between some of the Add/Drop nodes 120-1 to 120-4. Moreover, in the ninth embodiment, a configuration in which the cores in each add/drop node 120 are divided into a transmission core and a reception core has been described. However, as shown in
As described above in the embodiments, a connector connected to an MCF drops an optical signal from a core through which an optical signal addressed to a subject node is transmitted, the core being exclusively allocated for communication between nodes among a plurality of cores. The connector adds an optical signal transmitted from the subject node among the plurality of cores to a transmission destination core. In this manner, when a communication system is configured using a connector that adds or drops an optical signal in respective cores, adding and dropping of optical signals to the MCF are facilitated.
By using the connectors described in the embodiments, it becomes easy to change a logical topology without changing a physical topology. For example, in the communication system 100 shown in
Hereinafter, a configuration example of a switching connector which enables a logical topology to be changed will be described.
As shown in
In the switching connector 510-1, when the connector 190-1 is connected to the MCFs 200-1 and 200-2, the core 201-1 of the MCF 200-1 and the cores 201-2 and 202-2 of the MCF 200-2 are the Add/Drop targets of optical signals. In this case, the cores 202-1 and 203-1 of the MCF 200-1 and the core 203-2 of the MCF 200-2 are not used for transmission of optical signals. When the connector 190-1 is selected in the switching connector 510-1, the Add/Drop node 120-1 can add and drop optical signals as the node shown in
As shown in
In the switching connector 520-1, when the connector 190-1 is connected to the MCFs 200-1 and 200-2, the core 201-1 of the MCF 200-1 and the cores 201-2 and 202-2 of the MCF 200-2 are the Add/Drop targets of optical signals. In this case, the cores 202-1 and 203-1 of the MCF 200-1 and the core 203-2 of the MCF 200-2 are not used for transmission of optical signals. When the connector 190-1 is selected in the switching connector 510-1, the Add/Drop node 120-1 can add and drop optical signals as the node shown in
In
A configuration in which an internal connection of a connector can be changed dynamically instead of changing a connector that connects together two MCFs will be described.
The switching connector 530 can select whether optical signals will be relayed between two cores or whether optical signals will be added or dropped to of two cores on the basis of a selection signal input from the outside. For example, when selection signals for selecting “add/drop,” “relay,” and “relay” are input to the path switching units 531-1, 531-2, and 531-3, respectively, the switching connector 530 operates as the connector 150-1 shown in
Although a configuration example which is configured to use a Mach-Zehnder interferometer has been described in the switching connector 530 shown in
Optical signals of the cores 201-1, 202-1, and 203-1 of the MCF 200-1 are split by an optical system formed by the lenses 541 and 542 and are directed to the MEMS 543. Mirrors 543a, 543b, and 543c of which the tilt angle can be changed are attached to respective portions of the surface of the MEMS 543, on which optical signals are incident. The optical signals split by the lenses 541 and 542 are reflected by the mirrors attached to the MEMS 543 and are directed to the MEMS 544. Mirrors 544a, 544b, and 544c of which the tilt angle can be changed are attached to portions of the surface of the MEMS 544, on which optical signals are incident. The configuration of the MEMS 544 is similar to the configuration of the MEMS 543. The optical signals reflected by the MEMS 543 are reflected by the mirrors attached to the MEMS 544 and are incident on an optical system formed by the lenses 545 and 546. The optical signals collimated by the optical system are added to the cores 201-2, 202-2, and 203-2 of the MCF 200-2. Paths through which the optical signals from the cores of the MCF 200-1 are relayed to the respective cores of the MCF 200-2 are the above-described paths. When optical signals from the cores of the MCF 200-2 are relayed to the respective cores of the MCF 200-1, the paths are reverse to the above-described paths.
By changing the tilt angles of the mirrors provided on the surfaces of the MEMSs 543 and 544, it is possible to add or drop optical signals. For example, as shown in
By changing the tilt angles of the mirrors provided on the surfaces of the MEMSs 543 and 544, it is possible to select whether an optical signal transmitted through the core of the MCF will be relayed or dropped. Moreover, by changing the tilt angle of the mirror, it is possible to select whether an optical signal input from the outside of the switching connector 540 will be added to the core of the MCF.
Although a configuration example which uses MEMS has been described in the switching connector 540 shown in
When any one of the switching connectors shown in
In the communication systems of the embodiments, a core in which the number of adjacent cores in an MCF is small may be allocated to a core used for transmitting an optical signal of which the transmission distance is long. For example, a core in which the number of adjacent cores is the smallest may be allocated for transmission of an optical signal of which the transmission distance is the longest, and cores may be allocated in descending order of the number of adjacent cores according to the length of the transmission distance. Moreover, a core exclusively allocated for a communication path between nodes may be selected on the basis of a communication quality (for example, a transmission speed, a bit error rate, an optical signal strength, or the like) required in communication between nodes. Moreover, a core exclusively allocated for a communication path between nodes may be selected on the basis of noise applied to an optical signal transmitted in a communication path between nodes.
In the communication systems of the embodiments, a configuration in which nodes are connected together by one MCF has been described. However, nodes may be connected together by a plurality of MCFs. In this case, a plurality of connectors may be provided in each node. Moreover, when a plurality of MCFs are provided between nodes, the MCFs may be divided into an MCF of an active system (0-system) and an MCF of a standby system (1-system) in a communication system having a dual-system configuration. Moreover, MCFs may be provided in respective transmission directions of an optical signal so that the MCFs are divided into a reception MCF and a transmission MCF in each Add/Drop node 120.
The arrangement of cores in an MCF shown in the description of the embodiments is an example, and an MCF having a core arrangement other than the core arrangements shown in
In the communication systems of the embodiments, although a configuration in which Add/Drop nodes are directly connected together by an MCF and an Add/Drop node and a transceiving node are directly connected together by an MCF has been described, nodes may be connected together via a plurality of MCFs and relay nodes. The relay nodes may perform amplification for compensating attenuation of optical signals in transmission between nodes, for example. Moreover, a connector having a relaying function only may be used as the relay node.
In the embodiments, although a single mode configuration in which cores in an MCF propagates only one propagation mode has been described, a multi-mode configuration in which cores in an MCF propagates a plurality of propagation modes may be used. That is, a multi-core multi-mode optical fiber may be used for connection between nodes. When a multi-core multi-mode optical fiber is used for connection between nodes, a connector provided in each node, an optical device in which an optical signal passes through a communication path, and the like need to be capable of transmit signals in multiple modes.
In the embodiments, a configuration in which an MCF is used for connection between nodes has been described. However, one or a plurality of single-core fibers (SCFs) may be used for connection between nodes. When SCFs are used for connection between nodes, a conversion connector that connects an MCF to a plurality of SCFs or a conversion connector that connects a connector to a plurality of SCFs is used.
A conversion connector 400-1 is used for connection between the MCF 200-21 and the SCFs 451 to 453. The conversion connector 400-1 connects the cores 201-21, 202-21, and 203-21 of the MCF 200-21 to the SCFs 451, 452, and 453, respectively. A conversion connector 400-2 is used for connection between the MCF 200-22 and the SCFs 451 to 453. The conversion connector 400-2 connects the cores 201-22, 202-22, and 203-22 of the MCF 200-22 to the SCFs 451, 452, and 453, respectively.
The conversion connectors 400-1 and 400-2 have a configuration similar to that of a fan-in device or a fan-out device. By using the conversion connectors 400-1 and 400-2, it is possible to use the SCF in a partial segment of the connection between nodes.
The Add/Drop node 120-1 further includes a conversion connector 410-1. The conversion connector 410-1 is attached to a side of the connector 150-1 close to the Add/Drop node 120-2. The Add/Drop node 120-2 further includes a conversion connector 410-2. The conversion connector 410-2 is attached to a side of the connector 150-2 close to the Add/Drop node 120-1. The SCFs 451 to 453 of the same number as the number of cores of the MCF 200 are used for the connection between the conversion connectors 410-1 and 410-2.
The conversion connector 410-1 connects the SCFs 451, 452, and 453 to the connector 150-1. The connector 150-1 performs input/output of optical signals to/from the conversion connector 410-1 instead of the MCF 200-2. The connector 150-1 connects the cores 202-1 and 203-1 of the MCF 200-1 to the SCFs 452 and 453, respectively, via the conversion connector 410-1. The conversion connector 410-1 adds an optical signal generated by the transmitting device 121-1 to the SCF 451 via the connector 150-1.
The conversion connector 410-2 connects the SCFs 451, 452, and 453 to the connector 150-2. The connector 150-2 performs input/output of optical signals to/from the conversion connector 410-2 instead of the MCF 200-2. The connector 150-2 connects the SCF 451 and 453 to the cores 201-3 and 203-3 of the MCF 200-3, respectively, via the conversion connector 410-2. The connector 150-2 connects an optical signal dropped from the SCF 453 to the receiving device 122-2 via the conversion connector 410-2.
The conversion connectors 410-1 and 410-2 has a configuration similar to that of a fan-in device or a fan-out device. By using the conversion connectors 410-1 and 410-2, it is possible to use the SCF for the connection between nodes.
MCF and SCF may be switched a plurality of times for the connection between one set of nodes. For example, MCF and SCF may be used for the connection between the Add/Drop nodes 120-1 and 120-2 in the order of MCF, SCF, MCF, SCF, and MCF. In this case, a conversion connector is used between the MCF and the SCF.
The connector 150-1 and the conversion connector 410-1 described in
As described above, the SCF may be used in one or a plurality of connections between the nodes in the communication system 100 shown in
In the embodiments, a core allocation example assuming that the amount of information transmitted from each node to another node is constant has been shown and described. However, when the amount of information transmitted to other nodes differs for each node, cores may be allocated according to the amount of information transmitted and received by each node and the number of cores used for each node to transmit signals may be changed.
While embodiments of the present invention have been described with reference to the drawings, a specific structure is not limited to the embodiments but the present invention embraces design modifications made without departing from the spirit of the present invention.
The present invention is applicable to a use in which it is indispensable to facilitate adding and dropping of optical signals in nodes connected to a multi-core fiber.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-230871 | Nov 2015 | JP | national |
This application is a 371 National Phase of PCT/JP2016/084583, filed on Nov. 22, 2016. Priority is claimed on Japanese Patent Application No. 2015-230871, filed Nov. 26, 2015, the content of both of the above applications is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/084583 | 11/22/2016 | WO | 00 |
