JP6449060B2 - Wavelength demultiplexing apparatus, optical communication system, and wavelength demultiplexing method - Google Patents

Description

  The present invention relates to an optical communication system that performs unicast communication and multicast communication via an optical fiber transmission line.

  As an economical optical access system, there is a passive optical network (PON). As shown in FIG. 1, a PON is composed of one optical subscriber line termination (OLT) 92, a plurality of optical network termination (ONU) 91, an optical fiber transmission line, and a 1 to n network. This is a network that performs point-to-multipoint communication via an optical multiplexer / demultiplexer (n is a natural number) 94. As an example of a PON system, a combination of TDM-PON using time division multiplexing (TDM) technology and WDM-PON using wavelength division multiplexing (WDM) technology, TDM technology, and WDM technology are combined. Examples include TWDM-PON.

  Typical standards for TDM-PON include gigabit class 1G-EPON (Ethernet (registered trademark) PON) standardized by IEEE 802.3 and 10 gigabit class 10G-EPON. These are collectively referred to as EPON.

  FIG. 2 shows a functional block diagram of the ONU 91 in EPON. The upstream main signal is transmitted to the OLT 92 through a port of a UNI-IF (User Network Interface) 11, a PON signal processing unit 12, and a port of a PON-IF (PON Interface) 13. On the other hand, the downlink main signal passes through the port of the PON-IF 13, the PON signal processing unit 12, and the port of the UNI-IF 11 and is transmitted to a home gateway, a user terminal, etc. under the ONU 91.

  The PON signal processing unit 12 includes an MPCP (Multi-Point Control Protocol) unit 122 that reports the amount of data in the upstream queue to the OLT 92 by a REPORT message and receives the upstream bandwidth allocation result from the OLT 92 by a GATE message. ing. The upstream signal processing unit 121 monitors the amount of data in the upstream queue and passes the queue length information to the MPCP unit 122. Further, the uplink signal processing unit 121 transmits the frame in the queue to the OLT 92 based on the band allocation information received by the GATE message, for example, the information of the transmission start time and the transmission end time.

  FIG. 3 shows a functional block diagram of the OLT 92 in EPON. The downlink main signal is transmitted to the ONU 91 through a SNI (Service Node Interface) port, a PON signal processing unit 22, and a PON-IF 21 port. On the other hand, the upstream main signal passes through the port of the PON-IF 21, the PON signal processing unit 22, and the port of the SNI-IF 22, and is transmitted to a switch or router of the higher level network. The PON signal processing unit 22 causes the ONU 91 to report the amount of data in the upstream queue by the REPORT message, and notifies the ONU 91 of the upstream bandwidth allocation result by the GATE message, and the REPORT message received from the ONU 91. A bandwidth allocating unit 224 that monitors the data amount of the queue in the ONU 91 and allocates the transmission order and the amount of data that can be transmitted to each ONU using a dynamic bandwidth allocation (DBA) algorithm is provided. Yes.

  In recent years, with the spread of broadband services, there has been a demand for broadband PON systems. For example, as shown in FIG. 4, one communication wavelength is assigned to each ONU 91 by using the WDM technology, and flexible and efficient user multiplexing is achieved by combining the WDM-PON with a wide bandwidth and the TDM technology and the WDM technology. There is a realized TWDM-PON.

  As shown in Non-Patent Document 1, in WDM-PON, power saving of the OLT 92 can be achieved by a band aggregation technique that changes the number of transceivers to be activated according to the traffic volume.

For example, it is assumed that n ONUs 91 are connected to one OLT 92 via the wavelength demultiplexing multiplexer 93, and the OLT 92 can transmit a downlink signal with (n + 1) wavelengths. Wavelengths λ _{d, u1} to λ _{d, un} are assigned to each ONU 91, and wavelengths λ _{d, b} are broadcast wavelengths that can be received by all ONUs 91. A threshold is set for the transmission rate of the downstream signal, and when the transmission rate exceeds the threshold, the downstream signal is transmitted using the wavelengths λ _{d, u1} to λ _{d, un} , and the transmission rate is reduced. When the value is below the threshold value, the downstream signal is transmitted using only the wavelength λd _{, b} .

The case where wavelengths λ _{d, u1} to λ _{d, un} are used corresponds to WDM-PON, and the case where wavelengths λ _{d, b} are used corresponds to TDM-PON. That is, by operating in a TDM-PON configuration in a state where traffic is low, an unused transmitter is shifted to a low power consumption sleep state, and the power consumption of the OLT 92 is reduced.

Such a band aggregation method can be realized by the following physical configuration, for example. For example, in the case of a WDM-PON using an arrayed waveguide grating (AWG) having a circularity, as shown in FIG. By using 32 and further adding broadcast wavelength λ _{d, b} , the downstream wavelength can be shared by n ONUs. The wavelength separation unit 31 is, for example, an (n + 1) × (n + 1) AWG. The optical multiplexing / demultiplexing unit 32 is, for example, a 1 × n power splitter.

  In the example of FIG. 5, the case where the configuration of the WDM-PON with the number of wavelengths used n and the configuration of the TDM-PON with the number of wavelengths used 1 have been described has been described. By preparing an arbitrary number of multicast wavelengths addressed to the ONU 91, it is possible to achieve more efficient power saving of the OLT 92.

For example, a WDM-PON capable of multicast communication can be configured as shown in FIG. The wavelengths λ _{d, m1} to λ _{d, mk} are wavelengths used for multicast communication. For example, λ _{d, m1} can be used for multicast communication to the two nodes ONU # 1 and ONU # 2.

  A configuration example of the wavelength demultiplexing apparatus for the downlink signal is shown in FIG. The downlink signal transmitted from the OLT 92 is separated into a unicast wavelength and a multicast wavelength by the wavelength separation unit 31. Each unicast wavelength is connected to an output port corresponding to the destination ONU 91 via the wavelength multiplexing unit 33. The multicast wavelength is demultiplexed by the optical multiplexing / demultiplexing unit 32 according to the number of destination ONUs, and is connected to an output port corresponding to the destination ONU 91. For example, in the case of a multicast wavelength to two nodes of ONU # 1 and ONU # 2, it is demultiplexed by a two-branch power splitter, and one output of the optical multiplexing / demultiplexing circuit 32 is sent to an output port addressed to ONU # 1. Connect the output to the output port addressed to ONU # 2.

  In an optical network in which unicast communication, multicast communication, and broadcast communication are mixed, the number of power branches varies depending on the number of destination ONUs, so that the optical loss varies, and a receiver with a large dynamic range must be provided on the ONU side. . Therefore, Patent Document 1 proposes an optical power loss compensation circuit in which an optical switch and an optical amplifier are combined in a TDM type optical access system.

JP 2010-57108 A

Masashi Tadokoro, Ryogo Kubo, Susumu Nishihara, Takashi Yamada and Hirotaka Nakamura, "Adaptive bandwidth aggregation mechanisms using a shared wavelength for energy-efficient WDM / TDM-PON", Proceedings of the 10th International Conference on Optical Internet, COIN 2012, Yokohama, Japan, WF. 2, pp. 1-2, May 2012. Ichikawa Takumi, Uesugi Takuya, Kubo Ryogo, “A Multicast AWG Router for Access Networks”, Proceedings of the IEICE Optical Communication Systems Symposium, Mishima, P-15, p. 34, December 2014.

  However, Non-Patent Document 2 does not disclose a specific configuration of an optical power loss compensation circuit in a wavelength routing system using a multicast wavelength. Further, when the amplification factor of the optical amplifier is determined based on the identifier given to the packet as in Patent Document 1, it is necessary to perform packet analysis in the wavelength demultiplexing device, which causes a processing delay. there were. Furthermore, there is a problem in that control messages for optical switch control need to be exchanged, and the communication band is compressed.

  The present invention has been made in view of such problems, and an object of the present invention is to increase the processing delay and not reduce the communication band in a wavelength routing system capable of multicast communication. The purpose is to maintain the optical reception power at each reception node.

The wavelength demultiplexing device according to the present invention is:
A wavelength demultiplexing apparatus connected between one transmission node and a plurality of reception nodes, and transferring a wavelength division multiplexed optical signal transmitted from the transmission node to at least one of the plurality of reception nodes,
A first wavelength separation unit that separates the wavelength-multiplexed optical signal transmitted from the transmission node for each wavelength band determined according to the number of nodes to which the wavelength-multiplexed optical signal is transmitted;
An optical amplifying unit that amplifies the optical signal of each wavelength band separated by the first wavelength separation unit at an amplification factor determined for each wavelength band;
A second wavelength demultiplexing unit that demultiplexes the optical signal of each wavelength band amplified by the optical amplifying unit into a communication wavelength determined according to the receiving node;
An optical multiplexing / demultiplexing unit that branches the optical signal of each communication wavelength in each wavelength band separated by the second wavelength separation unit into the number of nodes;
A wavelength multiplexing unit that multiplexes the optical signal of each communication wavelength in each wavelength band branched by the optical multiplexing / demultiplexing unit for each receiving node;
Is provided.

  In the wavelength demultiplexing device according to the present invention, communication wavelengths having the same number of nodes and different receiving nodes are adjacent to each other in the wavelength band, and the optical amplifying unit has the same number of nodes and the receiving nodes You may amplify the optical signal of a different communication wavelength collectively.

  In the wavelength demultiplexing device according to the present invention, an amplification factor adjustment unit that adjusts the amplification factor of the optical amplification unit so that the intensity of the optical signal when reaching the reception node is equal to or higher than the minimum light receiving sensitivity in the reception node. Furthermore, you may provide.

  In the wavelength demultiplexing device according to the present invention, the amplification factor adjustment unit is configured such that, among the receiving nodes having the same number of nodes, the intensity of the optical signal when reaching the receiving node having the maximum distance from the own device. The amplification factor of the optical amplifying unit may be adjusted so as to be equal to or higher than the minimum light receiving sensitivity at the receiving node.

An optical communication system according to the present invention includes:
A transmitting node for transmitting an optical signal;
A receiving node for receiving the optical signal;
A wavelength demultiplexing device according to the present invention connected to an optical fiber transmission line connecting the transmitting node and the receiving node;
Is provided.

The wavelength demultiplexing method according to the present invention is:
A wavelength demultiplexing method that is connected between one transmitting node and a plurality of receiving nodes and transfers a wavelength multiplexed optical signal transmitted from the transmitting node to at least one of the plurality of receiving nodes,
The first wavelength separation unit separates the wavelength-multiplexed optical signal transmitted from the transmission node for each wavelength band determined according to the number of nodes to which the wavelength-multiplexed optical signal is transmitted,
An optical amplification unit amplifies the optical signal of each wavelength band separated by the first wavelength separation unit at an amplification factor determined for each wavelength band;
A second wavelength separation unit, which separates the optical signal of each wavelength band amplified by the optical amplification unit into a communication wavelength determined according to the reception node;
The optical multiplexing / demultiplexing unit branches the optical signal of each communication wavelength in each wavelength band separated by the second wavelength separation unit into the number of nodes corresponding to the wavelength band,
The wavelength multiplexing unit multiplexes the optical signal of each communication wavelength in each wavelength band branched by the optical multiplexing / demultiplexing unit for each receiving node.

  The above inventions can be combined as much as possible.

  By arranging different wavelengths for communications with different numbers of receiving nodes, the present invention reduces optical power loss based on wavelength information without requiring packet analysis in a wavelength demultiplexing device and a control protocol with an external device. Since it can be estimated, an increase in processing delay and compression of the communication band can be avoided.

It is an example of a structure of a PON system. It is an example of the structure of ONU in EPON. It is an example of the structure of OLT in EPON. It is an example of a structure of a WDM-PON system. An example of adding a broadcast wavelength in WDM-PON will be described. An example of the multicast communication in WDM-PON is shown. It is an example of a structure of the related wavelength demultiplexing apparatus. It is an example of wavelength arrangement which concerns on embodiment of this invention. 1 is an example of a configuration of a wavelength demultiplexing device according to a first embodiment. It is an example of the conversion table of a wavelength group and an amplification factor. 6 is an example of an optical communication system according to a second embodiment. 6 is an example of a configuration of a wavelength demultiplexing apparatus according to a second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below. These embodiments are merely examples, and the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
An optical communication system according to the present embodiment includes a transmission device that transmits an optical signal, a reception device that receives an optical signal, and a wavelength demultiplexing device that is connected to an optical transmission line that connects the transmission device and the reception device. Prepare. The optical communication system according to the present embodiment is an optical network in which one transmission node and a plurality of reception nodes are connected in a point-to-multipoint form. In the wavelength demultiplexing apparatus according to this embodiment, one transmission node is connected to an input-side port, and a plurality of reception nodes are connected to an output-side port.

  The optical communication system according to the present embodiment is, for example, a PON system in which one OLT 92 and a plurality of ONUs 91 are connected via an optical transmission line as shown in FIG. In this case, the input-side port of the wavelength demultiplexing device 93 is connected to the OLT 92 that functions as a transmitting device, and the output-side port of the wavelength demultiplexing device 93 is connected to the ONU 91 that functions as a receiving device.

  The OLT 92 that functions as a transmission node transmits a wavelength multiplexed optical signal, and the ONU 91 that functions as a reception node receives the wavelength multiplexed optical signal. Hereinafter, the case where the optical communication system according to the present embodiment transmits a downlink signal from the OLT 92 to the ONU 91 in the PON system as shown in FIG. 6 will be described.

  An example of the transmission wavelength arrangement of the downlink signal in this embodiment is shown in FIG. The wavelength band is determined according to the number of receiving nodes that is the number of destination nodes. For example, the wavelength band for unicast communication with the number of reception nodes of 1 is defined as the wavelength group W1, the wavelength band for multicast communication with the number of reception nodes of 2 is defined as the wavelength group W2, and the number of reception nodes is n. The wavelength band for broadcast communication is defined in the wavelength group Wn. As the wavelength band having two or more receiving nodes, for example, 1.0 to 1.3 μm including T band and O band is used.

In addition, a wavelength within each wavelength band is assigned to each ONU 91 as a communication wavelength. For example, in the wavelength group W1, the unicast wavelength to ONU # 1 is λ _{d, u1} , the unicast wavelength to ONU # 2 is wavelength _λd , _u2 ,..., And the unicast wavelength to ONU # n is λ. _{Let d, un} . In the wavelength group W2, λ _{d, m 1} , λ _{d, m 2} ,... Λ _{d, mk1} are prepared as multicast wavelengths to the two nodes. Multicast wavelengths to two nodes exist in the number of combinations for selecting two nodes from n nodes, and the maximum is n × (n−1) / 2. For example, the multicast wavelength λ _{d, m1} is used for multicast communication to ONU # 1 and ONU # 2.

In the wavelength group W3, λ _{d, m (k1 + 1)} , λ _{d, m (k1 + 2)} ,..., Λ _{d, mk2} are prepared as multicast wavelengths to the three nodes. Multicast wavelengths to 3 nodes are the number of combinations for selecting 3 nodes from n nodes, and the maximum is n × (n−1) × (n−2) / 6. For example, the multicast wavelength λ _{d, m (k1 + 1)} is used for multicast communication to ONU # 1, ONU # 2, and ONU # 3.

Further, a broadcast wavelength λ _{d, mk} is prepared for broadcast communication to n nodes. The broadcast wavelength λ _{d, mk} is a wavelength that can be received by all ONUs 91.

In the wavelength demultiplexing device 93, in order to facilitate wavelength separation and optical amplification of unicast wavelengths and multicast wavelengths having the same number of receiving nodes, each ONU # 1 is used for unicast communication or multicast communication having the same number of receiving nodes. It is desirable to use adjacent wavelengths as communication wavelengths assigned to .about. # N. For example, as shown in FIG. 8, the wavelengths λ _{d, m 1} , λ _{d, m 2} ,..., Λ _{d, mk1} assigned to the ONUs # 1 to #n in the wavelength group W2 are adjacent to each other. preferable. However, if the wavelength demultiplexing device 93 can appropriately perform multiplexing / demultiplexing of each wavelength, these wavelengths do not necessarily have to be adjacent to each other.

A unicast wavelength used for transmission to any one node is a wavelength group W1, a multicast wavelength to any two nodes is a wavelength group W2,..., And a broadcast wavelength to a Wn node is a wavelength group Wn. It is desirable to provide a guard band (GB) between the wavelength groups in order to facilitate separation by the wavelength separation unit 31. In addition, the interval C between the start wavelengths λ _{d, u1} , λ _{d, m 1} , λ _{d, m (k1 + 1)} ,..., Λ _{d, mk} of each wavelength group may be a constant frequency interval or a constant wavelength interval. desirable.

  A configuration example of the wavelength demultiplexing device 93 for the downlink signal in the present embodiment is shown in FIG. The downstream signal transmitted from the OLT 92 is transmitted to any one of the ONU # 1 to the ONU # n via the wavelength demultiplexing device 93.

  The wavelength demultiplexing device 93 includes a wavelength demultiplexing unit 31, optical amplifying units 34-1 to 34-n, a wavelength demultiplexing unit 35, an optical multiplexing / demultiplexing unit 32, a wavelength multiplexing unit 33, and an amplification factor adjusting unit 36. The wavelength separation unit 31 separates the wavelength-multiplexed downlink signal into each wavelength group. The wavelength group has a wavelength band determined according to the number of destination nodes.

The optical amplifying units 34-1 to 34-n amplify the downlink signal at an amplification factor determined for each wavelength group. Since signals in the same wavelength group have the same number of reception nodes, amplification is performed in a lump by the optical amplification units 34-1 to 34-n at the subsequent stage. For example performs amplified by the optical amplifier unit 34-1 of the amplification factor _{G 1} with respect to wavelength group W1, perform amplification by an optical amplifier unit 34-2 of the amplification factor _{G 2} is with respect to the wavelength group W2. However, the optical amplifiers 34-1 to 34-n may be an optical amplifier array in which a plurality of optical amplifiers having different amplification factors are arranged, or may be an optical amplifier having a variable amplification factor.

The wavelength separation unit 35 separates the optical signal of each wavelength band amplified by the optical amplification units 34-1 to 34-n into a communication wavelength determined according to the ONU 91. For example, the wavelengths λ _{d, m1} assigned to ONU # 1 and ONU # 2 are separated. Thereby, the unicast wavelength and the multicast wavelength are separated.

Each wavelength λ _{d, u 1} , λ _{d, u 2} ,..., Λ _{d, un} included in the wavelength group W 1 used for unicast communication is addressed to ONU # 1, ONU # 2,. Connected to the output port. Each communication wavelength included in the wavelength group W <b> 1 used for multicast communication is output to the optical multiplexing / demultiplexing unit 32.

  The optical multiplexing / demultiplexing unit 32 branches the power of the multicast wavelength by a power splitter or the like according to the number of receiving nodes. The number of branches is, for example, 2 branches if the number of receiving nodes is 2, and 3 branches or 4 branches if the number of receiving nodes is 3.

For example, when the wavelength λ _{d, m1} is used for multicast communication to ONU # 1 and ONU # 2, it is included in the wavelength group W2 in which the number of receiving nodes is 2, so that the two-branch power splitter in the optical multiplexing / demultiplexing circuit Branch optical power. Then, an output from one optical multiplexing / demultiplexing unit 32 is connected to a wavelength multiplexing unit 33 which is a wavelength multiplexing device output port addressed to ONU # 1, and an output from the other optical multiplexing / demultiplexing unit 32 is directed to ONU # 2. It is connected to the wavelength multiplexer 33 which is the wavelength multiplexing device output port.

The wavelength multiplexing units 33-1 to 33-n multiplex the wavelengths addressed to the respective ONUs and transmit the multiplexed downlink signals to the respective ONUs # 1 to #n. For example, the wavelength multiplexing unit 33-1 connected to the ONU # 1 includes the wavelength λ _{d, u1} assigned to the ONU # 1 in the wavelength group W1 and the wavelength assigned to the ONU # 1 in the wavelength group W2. λ _{d, m1} and wavelength λ _{d, m (k1 + 1)} assigned to ONU # 1 in the wavelength group W3 are multiplexed. Thereby, the signal for unicast communication and the signal for multicast communication are multiplexed on the wavelength multiplexed optical signal transmitted to ONU # 1.

  The amplification factor adjustment unit 36 adjusts the amplification factor of each of the optical amplification units 34-1 to 34-n based on the wavelength information. The wavelength information is, for example, for each wavelength or wavelength group. In this case, for example, as shown in FIG. 10, a conversion table in which the amplification factor is associated with each wavelength or each wavelength group is created in advance. The amplification factor is determined according to the number of optical power branches in the optical multiplexing / demultiplexing unit 32 at the subsequent stage, the optical power loss from the wavelength demultiplexing device 93 to the ONU 91, and the minimum light receiving sensitivity in the ONU 91.

  When each ONU 91 receives an optical signal having a communication wavelength included in the wavelength group W2, the amplification factor adjustment unit 36 makes the optical amplification unit 34-2 so that the optical reception power is equal to or higher than the minimum light receiving sensitivity in all the ONUs 91. It is preferable to adjust the amplification factor. Thereby, the amplification factor of the optical amplifying units 34-1 to 34-n can be appropriately set based on the estimated optical power loss, and the optical reception power at the reception node can be maintained above the minimum light reception sensitivity.

Further, the distance between the OLT 92 and each ONU 91 may be considered. It is possible to employ an amplification factor for the wavelength that is the maximum distance in each wavelength group. For example, in the wavelength group W2, the amplification factors that can be received at or above the minimum light receiving sensitivity in each ONU 91 are G ₂₁ , G ₂₂ ,..., G _2k1 , and the amplification factors for the wavelengths that are the maximum distance are G ₂₁ . If, adopting _{G 21} as an amplification factor _{G 2} of the optical amplifier unit 34-2. Further, when G ₂₁ > G ₂₂ >...> G _2k1 , G ₂₁ may be adopted as the amplification factor G ₂ of the optical amplification unit 34-2.

  However, it is desirable that the conversion table can reset the amplification factor corresponding to each wavelength or each wavelength group in accordance with the change in the distance between the transmission / reception nodes or the change in the number of reception nodes. Further, it is desirable that the wavelength demultiplexing device 93 can be accessed from a remote place and reset. As an access method to the wavelength demultiplexing device 93 for resetting, a control interface may be used, or a communication interface with the OLT 92 or the ONU 91 may be used. In order to suppress an increase in power consumption due to the installation of the optical amplifying units 34-1 to 34-n, the amplification factor of each of the optical amplifying units 34-1 to 34-n is an optical power at or above the minimum light receiving sensitivity at the receiving node. It is desirable to set the value as small as possible.

(Embodiment 2)
In the first embodiment, the application to the downlink communication of the WDM-PON in which the OLT that is one parent node and the ONUs that are a plurality of child nodes are connected in a point-to-multipoint form has been described. Applies to multicast communications in any point-to-multipoint network using WDM technology. Further, by constructing a plurality of point-to-multipoint networks of Embodiment 1 in parallel, multicast communication between any node and any other node in an optical network in which all nodes are connected in a full mesh form Apply.

  FIG. 11 shows an example of an optical communication system according to the present embodiment. In the optical communication system according to the present embodiment, the nodes 90 are connected in the form of a full mesh. Each node 90 is connected to the network via a wavelength demultiplexing device 93.

  The configuration of the wavelength demultiplexing device 93 in this embodiment is the same as the configuration shown in FIG. 9 described in the first embodiment. However, in this embodiment, the connection relationship of the wavelength demultiplexing device 93 is different. For example, in the wavelength demultiplexer 93 connected to the node # 1, the OLT 92 in FIG. 9 becomes the node # 1, and the ONU 91 in FIG. 9 becomes the nodes # 2 to # 5. In the wavelength demultiplexing multiplexer 93 connected to the node # 5, the OLT 92 in FIG. 9 becomes the node # 5, and the ONU 91 in FIG. 9 becomes the nodes # 1 to # 4. The same applies to the other nodes # 2, # 3, and # 4.

  Therefore, the invention according to Embodiment 1 can also be applied to multicast communication between an arbitrary node and another arbitrary node in an optical network in which all nodes are connected in the form of a full mesh.

  As described above, the invention according to this embodiment separately prepares unicast / multicast / broadcast wavelengths according to the number of branches in the wavelength division multiplexing network, and uses the wavelength information in the wavelength demultiplexing device 93 as a relay node. Based on this, the intensity of the optical signal is amplified. By continuously arranging wavelengths according to the number of branches of the wavelength separation unit 35, signal separation and amplification at the relay node are facilitated. Thus, in the invention according to the present embodiment, the number of branches can be specified by the transmission wavelength, so that message exchange between the transmission node and the relay node becomes unnecessary. Further, the packet analysis for recognizing the identifier becomes unnecessary in the relay node. Therefore, according to the present invention, it is possible to reduce variations in light intensity at the reception node while avoiding an increase in delay required for message exchange between the transmission node and the relay node and an increase in processing delay at the relay node.

  The present invention can be applied to the information communication industry.

11: UNI-IF
12: PON signal processing unit 121: Upstream signal processing unit 122: MPCP unit 123: Downstream signal processing unit 13: PON-IF
21: PON-IF
22: PON signal processing unit 221: Upstream signal processing unit 222: MPCP unit 223: Downstream signal processing unit 224: Band allocation unit 23: SNI-IF
31: Wavelength separation unit 32: Optical multiplexing / demultiplexing units 33-1, 33-2, 33-n: Wavelength multiplexing units 34-1, 34-2, 34-n: Optical amplification unit 35: Wavelength separation unit 36: Amplification factor Coordinator 90: Node 91: ONU
92: OLT
93: Wavelength demultiplexer 94: Optical multiplexer / demultiplexer 95: Optical fiber transmission line

Claims (6)

A wavelength demultiplexing apparatus connected between one transmission node and a plurality of reception nodes, and transferring a wavelength division multiplexed optical signal transmitted from the transmission node to at least one of the plurality of reception nodes,
A first wavelength separation unit that separates the wavelength-multiplexed optical signal transmitted from the transmission node for each wavelength band determined according to the number of nodes to which the wavelength-multiplexed optical signal is transmitted;
An optical amplifying unit that amplifies the optical signal of each wavelength band separated by the first wavelength separation unit at an amplification factor determined for each wavelength band;
A second wavelength demultiplexing unit that demultiplexes the optical signal of each wavelength band amplified by the optical amplifying unit into a communication wavelength determined according to the receiving node;
An optical multiplexing / demultiplexing unit that branches the optical signal of each communication wavelength in each wavelength band separated by the second wavelength separation unit into the number of nodes;
A wavelength multiplexing unit that multiplexes the optical signal of each communication wavelength in each wavelength band branched by the optical multiplexing / demultiplexing unit for each receiving node;
A wavelength demultiplexing device comprising: Communication wavelengths having the same number of nodes and different receiving nodes are adjacent to each other in the wavelength band,
The optical amplifying unit collectively amplifies optical signals of communication wavelengths having the same number of nodes and different receiving nodes;
The wavelength demultiplexing device according to claim 1. An amplification factor adjustment unit that adjusts the amplification factor of the optical amplification unit so that the intensity of the optical signal when reaching the reception node is equal to or higher than the minimum light receiving sensitivity in the reception node;
The wavelength demultiplexing device according to claim 1 or 2. The amplification factor adjustment unit has an optical signal intensity equal to or higher than the minimum light receiving sensitivity of the receiving node when the node reaches the receiving node having the maximum distance from the own node among the receiving nodes having the same number of nodes. Adjusting the amplification factor of the optical amplification unit,
The wavelength demultiplexing device according to claim 3. A transmitting node for transmitting an optical signal;
A receiving node for receiving the optical signal;
The wavelength demultiplexing device according to any one of claims 1 to 4, connected to an optical fiber transmission line that connects the transmission node and the reception node;
An optical communication system comprising: A wavelength demultiplexing method that is connected between one transmitting node and a plurality of receiving nodes and transfers a wavelength multiplexed optical signal transmitted from the transmitting node to at least one of the plurality of receiving nodes,
The first wavelength separation unit separates the wavelength-multiplexed optical signal transmitted from the transmission node for each wavelength band determined according to the number of nodes to which the wavelength-multiplexed optical signal is transmitted,
An optical amplification unit amplifies the optical signal of each wavelength band separated by the first wavelength separation unit at an amplification factor determined for each wavelength band;
A second wavelength separation unit, which separates the optical signal of each wavelength band amplified by the optical amplification unit into a communication wavelength determined according to the reception node;
The optical multiplexing / demultiplexing unit branches the optical signal of each communication wavelength in each wavelength band separated by the second wavelength separating unit into the number of nodes corresponding to the wavelength band,
The wavelength multiplexing unit multiplexes the optical signal of each communication wavelength in each wavelength band branched by the optical multiplexing / demultiplexing unit for each receiving node.
Wavelength demultiplexing method.

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