JP3352294B2 - Wavelength control method and communication terminal station using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength control method for an optical transmitter in a wavelength division multiplex communication system, and more particularly to a wavelength control method having a wavelength control function for transmitting a wavelength control signal to any of a plurality of communication nodes. A communication terminal that includes a communication node and a terminal that accomplishes the method.

[0002]

2. Description of the Related Art Wavelength multiplex communication using an optical signal as a transmission medium can have a large number of independent channels for different wavelengths in one transmission line. Since multiplexing on the time axis such as frame synchronization is not required, it is not necessary to match the transmission speed of each channel, which is suitable for multimedia communication that requires network flexibility.

As an example of a wavelength division multiplex communication system, there is a system having a wavelength division multiplex communication system and an independent communication system signal in one transmission line in a passive star configuration. In this system, a wavelength division multiplex communication system is used for one-to-one and one-to-many line information communication. On the other hand, an independent line communication system is used for control communication and packet communication of a wavelength division multiplex communication system (hereinafter, referred to as a packet communication system).

FIG. 5 shows an example of a wavelength arrangement transmitted in one transmission line. The 1.5 μm band is assigned to the wavelength multiplex communication system, and the 1.3 μm band is assigned to the packet communication system. The wavelength division multiplexing communication system has m (smaller than the number n of communication nodes) independent channels, and each communication node occupies the channel as necessary and performs communication. Packet communication system is FD
Shared by all communication nodes using a protocol such as DI (Fiber Distributed Data Interface).

In order to increase the number of channels in a wavelength division multiplexing communication system, the wavelength interval between channels (hereinafter referred to as a channel interval) is set to the order of 10 GHz (for example, 0.08 nm when the wavelength is converted in the 1.55 μm band). In this case, it is necessary to control so as to maintain the transmission wavelength of each communication node. Several methods have been proposed as a method for keeping the channel spacing of the transmission wavelength from each distributed communication node constant (for example, the publication Electronics Letters, Vol. 23 (1987), No. 23, 1243-1245,
“Frequency stabilization of FDM optical signals o
riginating from different locations ”).

[0006] Above all, the so-called batch control FCS (Floating Channel Stack) method in Japanese Patent Application No. 7-239703, filed by the present inventors, makes it easy to initialize and reset the wavelength. In addition, the transmitter of the communication node does not need the wavelength detecting means.

Hereinafter, an outline of the collective control FCS method will be described. In this method, a wavelength control node installed in the network detects the entire wavelength arrangement of the wavelength division multiplex communication system, and transmits control information for maintaining a constant wavelength interval between adjacent channels of the wavelength division multiplex communication system. Broadcasting is performed as a packet in a packet communication system. Each communication node controls the wavelength of the light source of the transmitter of its wavelength division multiplex communication system based on the control information of the wavelength control packet so that the wavelength interval between adjacent channels is constant.

FIG. 6 shows a configuration diagram of the wavelength division multiplexing communication system. Terminal stations 211 to 21n are communication nodes 221 to 22
n, the wavelength control node 61 is connected to the star coupler 23 via optical fibers 62 and 63 via optical fibers 241 to 24n and 251 to 25n, and a network is configured. Communication nodes 221 to 22n, wavelength control node 6
The optical signal transmitted from 1 is distributed by the star coupler 23 to all communication nodes 221 to 22n (including its own station).

FIG. 7 shows an example of the operation of the collective control FCS method. In the figure, the abscissa indicates the wavelength, and the wavelength that has already been emitted is channel 1, channel 4 is being used based on the longest wavelength, and the next emission and transmission are to be performed. ch5 is on the short wavelength side of the wavelength range of the wavelength division multiplexing communication system (FIG. 7a), gradually shifts to the long wavelength side, calms down to a steady state wavelength arrangement, and maintains this wavelength arrangement (FIG. 7b). If there is a communication node ch3 whose transmission has been completed and has stopped emitting light (FIG. 7C),
The plurality of communication nodes that emit light on the short wavelength side gradually shift the wavelength to the long wavelength side. As a result, in the steady state, the channel numbers set in the steady state as ch4 and ch5 are converted into ch3 and ch4, and the wavelength of each communication node is set at equal wavelength intervals from the long wavelength end of the wavelength range of the wavelength division multiplex communication system. (FIG. 7d).

FIG. 8 is a diagram showing the data format of a wavelength control packet transmitted by the packet communication system in order for the wavelength control node 61 to control the wavelengths of the communication nodes 221 to 22n in the system. A 2-bit wavelength control code is assigned to one channel. The maximum number of channels is m, and the data length is m × 2 bits. For each channel, '00' is unused, '01' shifts the wavelength to the longer wavelength side, '10' shifts to the shorter wavelength side, '1'
1 'indicates that the status quo is maintained. This wavelength control packet is delivered to each of the communication nodes 221 to 22n and the wavelength control node 61 by a packet communication system, so that each of the communication nodes 22
1 to 22n perform operations such as whether the wavelength of the own station needs to be shifted or the current status is maintained according to the wavelength control code of the wavelength control packet of the channel number assigned to the own station when transmitting.

[0011] As another example of the collective control FCS method, two wavelength control nodes are provided, and when one of the two wavelength control nodes fails, the other takes over and sends out a wavelength control packet. Although a measure for preventing a situation in which transmission of each communication node is impossible is currently being filed, it is indispensable to enhance the reliability of the wavelength division multiplexing communication system.

[0012]

However, the conventional wavelength control method has the following problems.

In this method, a wavelength control node is required as a new component. Further, when the wavelength control node fails and the wavelength control packet cannot be transmitted, the wavelength of the transmitter of each communication node enters a free-run state, and the channel interval of the wavelength division multiplex communication system cannot be kept constant. . Further, since the wavelength control node also assigns channels, it is not possible to start a new transmission. For this reason, high reliability is required for the wavelength control node, and the cost is high.

Therefore, a first object of the present invention is to eliminate the need for a wavelength control node in the above-described wavelength control method. A second object of the present invention is to ensure that a wavelength control role (a role of transmitting a wavelength control packet) in an unsteady state, in which wavelength control must be performed frequently, is always performed.

Further, a third object of the present invention is to perform the shift of the wavelength control role without communication in the packet communication system. A fourth object of the present invention is to surely shift the wavelength controller.

[0016]

Since the number of channels in the wavelength division multiplex communication system is smaller than the number of terminal stations, there are communication nodes in which the wavelength division multiplex communication system is in a non-receiving state. By functioning as a wavelength control node of the communication node (using a wavelength tunable filter of the receiving system for detecting wavelength allocation), it is possible to perform the collective control FCS method without installing a wavelength control node.

[0017] with separate packet communication system with wavelength division multiplexing communication system and the WDM communication system, the WDM communication system
In the wavelength control method of a communication system including a plurality of communication nodes performing communication packet communication system and said wavelength
Communication nodes that are not receiving in the multiplex communication system
The wavelength arrangement of the wavelength multiplexing communication <br/> signal system is detected by the optical tunable filter receiving system as control role, the wavelength of the channel adjacent to the reference wavelength channel at one end of the wavelength range of the WDM communication system so that the distance is predetermined wavelength interval [Delta] [lambda], controls the transmission wavelength of the wavelength division multiplexing communication system of the communication node by the packet communication system, before
Starting or emitting light from a channel in a WDM communication system
From the optical stop, the channel interval becomes the wavelength interval Δλ.
Until the channel that started emitting light in the WDM communication system
The channel or the channel that has stopped emitting light
One of the communication nodes serves as the wavelength controller . Also, the wavelength
A multiplex communication system and a packet independent of the wavelength multiplex communication system.
A wavelength communication system and a packet communication system.
Communication system consisting of multiple communication nodes
The wavelength multiplexing communication system,
Communication node that does not perform the
The wavelength arrangement of the wavelength division multiplexing communication system with the wavelength tunable filter of
The wavelength multiplexing communication system at one end of the wavelength range.
Between the wavelengths of adjacent channels based on the wavelength of the channel
The distance is set to a predetermined wavelength interval Δλ.
WDM communication of the communication node by a packet communication system
Control the transmission wavelength of the system, and before the transition of the wavelength controller
This is performed in the packet communication system.

According to this method, a communication node that is not performing reception in the wavelength division multiplexing communication system detects the wavelength allocation of the entire wavelength division multiplexing communication system, and notifies each communication node of wavelength control information of each channel. The communication node using each channel controls its own transmission wavelength using the wavelength control information. As a result, transmission wavelengths are arranged at a fixed wavelength interval from the wavelength of the channel at one end of the wavelength range of the wavelength division multiplex communication system.

A communication terminal station comprising: a transmitting section for transmitting an optical signal by placing data on a transmission path; and a receiving section for detecting an optical signal addressed to the own station from the transmission path. Comprises a wavelength tunable semiconductor element that emits a predetermined wavelength driven by a wavelength control signal, and the receiving unit includes a wavelength tunable filter that filters a predetermined wavelength width driven by a filtered wavelength control signal, and the wavelength tunable filter. And an identification means for detecting an optical signal equal to or greater than a threshold value from the output of (i) and identifying a channel number and a wavelength of light emitted on the transmission path based on a relationship with the filtered wavelength control signal. The communication terminal station includes a communication node and a terminal station connected to the communication node, and the identification means includes an identification device, and a memory for storing data relating to the wavelength and the filtered wavelength control signal.
In this way, the discriminator sweeps the filtered wavelength control signal,
The wavelength is read from the memory from the voltage of the filtered wavelength control signal when 1 "is output, and the wavelength is compared with the wavelength of a wavelength row at a predetermined wavelength interval separately stored in the memory. Is output.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the drawings together with each embodiment.

[First Embodiment] In this embodiment, a communication node in a non-receiving state functions as a wavelength control node in a conventional example, using a wavelength tunable filter of a wavelength division multiplexing communication system receiving section as wavelength arrangement detecting means.

In this embodiment, in the steady state, one of them sends out the wavelength control packet and maintains the steady state. In an unsteady state (when a certain channel starts emitting light and stops emitting light), a communication node that receives a channel that has started emitting light or a channel that has stopped emitting light transmits a wavelength control packet and shifts to a steady state. .

The details will be described below with reference to the drawings.

FIG. 1 shows the transition of the wavelength control role in the wavelength control method of the present invention. The time axis is taken from the top to the bottom to indicate the transmission timing of the wavelength control packet (Tlp1 to Tlp15). Tlda is a repetition period of wavelength arrangement detection in an unsteady state. The figure shows an example of I) steady state → II) unsteady state due to the start of channel emission → III) steady state → IV) unsteady state due to stop of channel emission → V) steady state.

FIG. 2 is a system configuration diagram. The configuration is such that the wavelength control node 61 and the optical fibers 62 and 63 are deleted from FIG.

FIG. 3 shows the communication nodes 221-2 shown in FIG.
It is a block diagram of 2n. Each communication node is divided into a wavelength multiplex communication system and a packet communication system. The wavelength multiplexing communication system includes a wavelength control system 31, a wavelength variable LD 32, a wavelength variable LD drive circuit 34, an optical modulator 36, an optical modulator drive circuit 37, a wavelength variable filter 33, a wavelength variable filter drive circuit 35, a light receiving element 38, It comprises a receiving circuit 39. The packet communication system includes an LD 310, an LD driving circuit 311, a signal selection switch 318, a light receiving element 312, a receiving circuit 313, an amplifier 31
6. It comprises a discriminator 317. The transmission unit and the reception unit of the two communication systems are an optical multiplexer 314 and an optical demultiplexer 315, respectively.
Connected by

Here, the wavelength control system 31 transmits the wavelength variable LD 32 via the wavelength variable LD drive circuit 34 based on the contents of the wavelength control packet from the receiving circuit 313 of the packet communication system.
To move or maintain the emission wavelength. Further, the wavelength of the tunable filter 33 is controlled via the tunable filter driving circuit 35. When receiving a wavelength multiplex communication system,
The wavelength of the wavelength tunable filter 33 is made to match the wavelength of the channel addressed to the own station from the channels. When not receiving,
The wavelength of the wavelength tunable filter 33 is swept over the entire wavelength range of the wavelength division multiplex communication system, and based on the output of the discriminator 317 at that time, the wavelength arrangement is detected and a wavelength control packet is generated.

The wavelength tunable LD 32 is a transmission light source for a wavelength division multiplex communication system, and its wavelength is, for example, in the 1.5 μm band. Research for widening the wavelength tunable range is underway, but at the present practical level, a multi-electrode DBR (Dielectric
distributed Bragg Reflector type or DFB (Distributed
FeedBack) type, and the wavelength variable width is several nm.
For example, the IEICE Technical Report OQE (Opti
cal and Quantum Electronics) 89-116, "Three-electrode long cavity λ / 4 shift MQW-DFB laser".

The wavelength tunable filter 33 is used for reception of a wavelength division multiplex communication system and detection of a wavelength arrangement. In this embodiment, the wavelength band is the 1.5 μm band. The half width of the transmission spectrum is desirably about 1/5 to 1/10 of the ch interval (for example, when the ch interval is 5 GHz (corresponding to 0.04 nm in terms of wavelength in a 1.5 μm band), the half width is 1: 1).
GHz). As a device of the practical level, conference proceedings E
COC (Europian Conference on Optical Communicati)
on) '90 -605, "A fieldworthy, high performance, t
There is a fiber Fabry-Perot type described in “Unable fiber Fabry-Perot filter.” This element is an FSR (Free Spect
ral Range) has a transmission spectrum peak, but F
By setting the SR to be equal to or longer than the wavelength range of the wavelength division multiplexing communication system, it functions as an optical bandpass filter. The wavelength can be varied by a drive voltage. For example, in the wavelength multiplex communication system shown in FIG.
The filtering wavelength can be varied over the entire 5 μm band.

Further, the wavelength variable LD drive circuit 34 is a voltage control type current source, and drives (injects current) the wavelength variable LD 33 so as to have a wavelength corresponding to the control signal from the wavelength control system 31. When the above-mentioned three-electrode long-cavity λ / 4 shift MQW-DFB laser is used, a wavelength tunable LD
The drive circuit 34 has three outputs.

The wavelength tunable filter driving circuit 35 is a voltage control type voltage source. A wavelength control signal and a lock ON / OFF signal are input from the wavelength control system 31. Lock off state when receiving channel is selected and when not receiving,
In order to scan the filtering wavelength, the wavelength tunable filter 33 is set to a wavelength corresponding to the control signal from the wavelength control system 31.
Drive. During reception, the lock is ON, and the wavelength of the wavelength tunable filter 33 is locked to the wavelength of the reception channel.

The optical modulator 36 and the optical modulator driving circuit 37 transmit a wavelength-division multiplexed communication signal input from a terminal station connected among the terminal stations 211 to 21n.
This is for modulating the intensity of the 32 output light. When directly modulated by the current injected into the wavelength tunable LD 32, 0.1
Since a wavelength fluctuation of about nm occurs, a method of external intensity modulation by the optical modulator 36 is generally used.

The light receiving element 38 and the receiving circuit 39 are for receiving in a wavelength division multiplex communication system. The optical signal of the channel selected by the wavelength variable filter 33 is converted into an electric signal, and is reproduced as, for example, communication information of a digital signal. The reproduced reception signal is output to the terminal station.

The amplifier 316 amplifies the output of the light receiving element 38, and the discriminator 317 compares the signal with a threshold value.
Is output to the wavelength control system 31. Then, in correspondence with the control voltage supplied from the wavelength control system 31 to the wavelength tunable filter driving circuit 35, the wavelength control system 31 determines the wavelength of the channel on which the discriminator 317 outputs “1”. Or to detect.

The LD 310 is a light source of a packet communication system, and has a wavelength of, for example, a 1.3 μm band. The LD drive circuit 311 is a current source that modulates the LD 310 with a signal from the signal selection switch 318. In the present embodiment, high-density wavelength multiplexing is not performed in the packet communication system.
D310 is directly intensity modulated.

The signal selection switch 318 selects one of the transmission signal of the packet communication system from the terminal station and the wavelength control packet from the wavelength control system 31, and selects the LD drive circuit 31.
Enter 1 Here, the wavelength control packet is prioritized,
When two signals are input simultaneously, including data in the data format of the wavelength control packet shown in FIG. 8 described above, the transmission signal from the terminal station is saved in an internal buffer and transmitted after the wavelength control packet is transmitted. .

The light receiving element 312 and the receiving circuit 313 are for receiving a signal of a packet communication system.

The optical multiplexer 314 multiplexes an optical signal of the wavelength multiplex communication system in the wavelength band of 1.5 μm and an optical signal of the packet communication system in the wavelength band of 1.3 μm, and outputs the multiplexed signal to the optical fiber. On the other hand, the optical demultiplexer 315 separates the optical signal input from the optical fiber in the wavelength band, inputs the 1.5 μm band optical signal to the wavelength tunable filter 33, and outputs the 1.3 μm band optical signal to the light receiving element 312. input.

In this embodiment, all the communication nodes have a possibility of detecting the wavelength arrangement using the tunable filter 33 in the non-receiving state. The wavelength of the wavelength variable filter 33 is swept over the entire wavelength range of the wavelength division multiplex communication system, the output of the discriminator 317 at that time is monitored, and the wavelength arrangement of each channel is detected.

In the steady state, one of the communication nodes in the non-receiving state serves as a wavelength controller, and in the unsteady state (when a certain channel starts emitting light and stops emitting light), the channel or the light emitting which has started emitting light. In order to allow the communication node that receives the channel for which the transmission has been stopped (immediately before the start of reception and immediately after the end of reception) to serve as a wavelength controller, the timing of wavelength arrangement detection and transmission of a wavelength control packet is as follows. Here, immediately before the start of reception means a period from the unsteady state (FIG. 7A) at the start of light emission to the steady state (FIG. 7B). Immediately after the end of reception is when light emission of any communication node is stopped. This refers to the period from the unsteady state (FIG. 7c) to the steady state (FIG. 7d).

First, the timing of wavelength arrangement detection will be described.

Immediately before the start of reception and immediately after the end of reception, immediately after the state is entered, first, the wavelength allocation is detected once. Thereafter, when the wavelength control packet is transmitted by itself, T1da-ΔT (T1da-ΔT is, for example, 0.5 × T
After 1da), the wavelength arrangement is detected. When a wavelength control packet transmitted by another communication node is received, its T1d
After b (T1db is 2 × T1da), the wavelength allocation is detected. If a new wavelength control packet is received between the time when the wavelength control packet is received and the time when the wavelength allocation is detected, the time point is set as the starting point.

In the other non-reception state, if the wavelength control packet is transmitted by itself, the T1dc-ΔT (T
1dc, for example, performs wavelength allocation detection after 2 × T1da). When a wavelength control packet transmitted by another communication node is received, its T1dd (T1dd is, for example, 4 × T
After 1da), the wavelength arrangement is detected. If a new wavelength control packet is received between the time when the wavelength control packet is received and the time when the wavelength allocation is detected, the time point is set as the starting point.

Next, the transmission timing of the wavelength control packet will be described.

After detecting the wavelength arrangement, the wavelength control system 31 generates data of the wavelength control packet, and if necessary (described later),
A wavelength control packet is transmitted from the packet communication system. The transmission timing of the wavelength control packet is after ΔT (for example, ΔT = 0.5 × T1da) of the next wavelength arrangement detection.

The transmission of the wavelength control packet is performed when the following conditions are satisfied. (1) Immediately before the start of reception and immediately after the end of reception When the wavelength control packet transmitted by another communication node is not received for ΔT after the detection of the wavelength arrangement, (2) Other non-reception state The shift of the wavelength arrangement is detected. , And ΔT after detecting the wavelength arrangement,
When a wavelength control packet transmitted by another communication node is not received. Incidentally, the deviation of the wavelength arrangement referred to here is the same as FIG.
In the steady state of b and d, it means a deviation from the wavelength arrangement at a constant wavelength interval starting from ch1. This shift is caused by the output of the discriminator 317 and the wavelength tunable filter driving circuit 35 described above.
The wavelength based on the voltage supplied to the power supply is detected and compared with a predetermined wavelength interval.

By operating each communication node in this way, in the steady state, one of the communication nodes in the non-reception state becomes the reception node of the channel that causes the non-stationary state in the non-stationary state (however, during this operation, (A non-receiving state) sends out a wavelength control packet, and collective FCS control is performed.

Next, a specific example shown in FIG. 1 will be described.

In the example of this figure, there are five modes in place of the steady state and the non-steady state.

I) T1p1 to T1p4. The wavelength arrangement is in a steady state. Communication node X, which is one of the non-receiving communication nodes, is transmitting the wavelength control packet. Since the wavelength control packet is not transmitted when no deviation is detected in the wavelength arrangement, the interval is at least T1dc.

II) T1p5 to T1p7. T1p4 to T
Channel 1 starts to emit light during 1p5, and the wavelength arrangement becomes unsteady. Communication node A is from T1p4 to T1p
5, a reception request is received by the packet communication system, and the interval between transmission / reception of the wavelength control packet and detection of the wavelength arrangement is set to T1daΔT. As a result, the communication node A transmits the wavelength control packet to T
The wavelength is transmitted at a period of 1 pa, and the wavelength of the channel A becomes a wavelength interval of Δλ with the adjacent channel by the collective FCS control by the wavelength control packet, and the wavelength arrangement becomes a steady state. The communication node A, which has detected that the wavelength arrangement has become a steady state, adjusts the wavelength tunable filter to the wavelength of the channel A, and then confirms that the transmission source communication node of the channel A can receive data in the packet communication system. Then, reception on channel A is started.

III) T1p8 to T1p10. As in I), the communication node X sends a communication control packet.

IV) T1p11 to T1p13. T1p10
Between T1p11 and T1p11, the channel B stops emitting light, and the wavelength arrangement becomes an unsteady state. The communication node B that has received the channel B sets the interval between transmission / reception of the wavelength control packet and detection of the wavelength arrangement to T1daΔT. As a result, the communication node B sends out the wavelength control packet at the T1pa period, the free wavelength region created by stopping the light emission of the channel B by the collective FCS control by the wavelength control packet is narrowed, and the wavelength arrangement is changed. It becomes a steady state.
The communication node B that has detected that the wavelength allocation has reached a steady state sets the interval between transmission / reception of the wavelength control packet and detection of the wavelength allocation to T1dcΔT.

V) T1p13 to T1p15. As in I), the communication node X sends a communication control packet.

When one-to-many communication is performed in a wavelength division multiplexing system, there is no communication node in a non-receiving state, although the number of available channels in the wavelength division multiplexing communication system is smaller than the number of communication nodes. Can happen. In this situation, there is no communication node serving as the wavelength controller, and in some cases, interference between adjacent channels occurs. In this case, the communication node that has detected the interference stops receiving and informs the transmitting source communication node of stopping the reception in the packet communication system, and then serves as a wavelength controller. After the deviation of the wavelength arrangement is corrected, the wavelength of the optical filter is adjusted to the original reception channel, the transmission source is notified that the reception is possible, and the reception is started. In addition, since there is almost no case where a communication node that performs one-to-many communication information transmission is received by its own receiving unit, the communication control packet is transmitted to the communication packet system together with the wavelength multiplex communication system to perform wavelength control. It can be helpful.

In this embodiment, the wavelength controller can be shifted without communication in the packet communication system, and unnecessary traffic is not generated in the packet communication system.

[Second Embodiment] In this embodiment, the wavelength controller is shifted by communication in a packet communication system.

When the network is activated, one communication node becomes the wavelength controller, and notifies the other communication nodes of the termination of the wavelength controller before the node itself enters the reception state. The communication node in the non-reception state that has received this notification performs a wavelength control combination enable notification. The communication node currently serving as the wavelength controller selects one of the communication nodes that have issued the wavelength controller enable notification, and sends a wavelength controller combination notification to the communication node. The communication node that has received the wavelength control combination shift notification becomes the wavelength control combination. When the communication node enters the receiving state, the wavelength controller is shifted by the same procedure.

FIG. 4 shows an example of the shift of the wavelength controller in this embodiment. The time axis is taken from the top to the bottom to indicate the transmission timing of the wavelength control packet (T2p1-T2p1).
2p14). Here, the portion from T2p4 to T2p11 is enlarged because packet communication for transition is performed densely. T2d is a repetition period of the wavelength arrangement detection of the communication node serving as the wavelength controller. The communication node serving as the wavelength controller transmits the wavelength control packet only when a deviation in the wavelength arrangement is detected (including the unsteady state). As a result, the shortest transmission interval of the wavelength control packet is T2d. The figure shows a situation where the wavelength controller has shifted from the communication node A to the communication node B.

In the present embodiment, since the wavelength control role is reliably transferred, when a wavelength shift occurs in a steady state, the shift can be resolved without fail and interference between adjacent channels can be prevented.

Referring to FIG. 4, timings T2p1 to T2
At p4, the communication node A sweeps the wavelength of the optical signal in the transmission path of the receiving optical fiber, detects the channel number and the wavelength, and performs the same operation as described in the first embodiment. The control information relating to the maintenance / transition is transmitted as a wavelength control packet. Since the communication node A needs to receive information before the timing T2p5, the communication node A sends a wavelength control end notification to the effect that the own station ends the wavelength control role to the communication packet system at T2p5. In response to this end notification, T
Communication node B at 2p6, communication node C at T2p7,
At T2p8, the communication node D notifies the communication node A of the wavelength control combination enable notification through the communication packet system. In T2p9, the communication node A normally sends out a wavelength control packet in the same manner. Further, at T2p10, the communication node B is selected from among the communication nodes that have received the wavelength control combination enable notification, and a wavelength control combination shift notification is sent to the communication node B to the communication packet system. Then, the communication node B sweeps the wavelength of the wavelength tunable filter to detect the wavelength arrangement of the optical signal of the wavelength division multiplexing communication system, and in the same manner as the data format of the wavelength control packet transmitted from the communication node A at the timing T2p11. And sends a wavelength control packet to the packet communication system as a wavelength controller. At timings T2p12 to T2p14, the communication node B continuously sends out the wavelength control packet and continues until the time when the communication node B enters the receiving state.

[Other Embodiments] In the configuration of the communication node shown in FIG. 3, the wavelength control packet is transmitted from the wavelength control system 31 via the signal selection switch 318 to the LD drive circuit 3 as the transmission path of the wavelength control packet.
Although the example up to 11 has been given, the data of the wavelength control packet generated by the wavelength control system 31 may be temporarily sent to the terminal station and directly input to the LD drive circuit 310 as a transmission signal from the terminal station. In this case, the signal selection switch 318 becomes unnecessary. The other components are not limited to those described in the embodiments as long as they have the same function. The same applies to a system composed of several components.

In the above embodiment, an example is shown in which all communication nodes are provided with a wavelength control packet configuration. However, due to cost requirements and empirical rules in the system, not all communication nodes are used. The wavelength control packet system may be configured in a plurality of communication nodes. In this case, the wavelength control role can be limited to the plurality of communication nodes. However, the communication possibility, the communication stability, and the communication reliability are better than the case where one or two wavelength control nodes shown in the conventional example are used. It is effective in terms of.

[0064]

According to the present invention, the wavelength control node can be eliminated in the collective control FCS method. Further, according to the present invention, in an unsteady state in which wavelength control must be performed frequently, the wavelength controller can reliably transmit a wavelength control packet.

Further, according to the present invention, the wavelength controller can be shifted without communication in the packet communication system, and unnecessary traffic is not generated in the packet communication system. Further, according to the present invention, since the shift of the wavelength controller is reliably performed, when a shift occurs in the wavelength arrangement in a steady state, the shift can be reliably eliminated and interference between adjacent channels can be prevented. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a shift of a wavelength controller in a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a wavelength division multiplexing communication system to which the present invention is applied.

FIG. 3 is a configuration diagram of a communication node applied to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an example of a shift of a wavelength controller in a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a wavelength arrangement of a wavelength division multiplexing communication system.

FIG. 6 is a configuration diagram of a wavelength division multiplexing communication system applied to a conventional example.

FIG. 7 is an explanatory diagram showing an example of the operation of the FCS method.

FIG. 8 is a diagram showing a data format of a wavelength control packet by a wavelength control packet system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Terminal station 22 Communication node 23 Star coupler 24, 25 Optical fiber 31 Wavelength control system 32 Wavelength variable LD 33 Wavelength variable filter 34 Wavelength variable LD drive circuit 35 Wavelength variable filter drive circuit 36 Optical modulator 37 Optical modulator drive circuit 38 Light reception Element 39 Receiving circuit 310 LD 311 LD driving circuit 312 Light receiving element 313 Receiving circuit 314 Optical multiplexer 315 Optical demultiplexer 316 Amplifier 317 Discriminator 318 Signal selection switch 61 Wavelength control node 62, 63 Optical fiber

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14/00-14/08 H04L 12/44

Claims (3)

(57) [Claims] 1. A with separate packet communication system with wavelength division multiplexing communication system and the WDM communication system, the WDM communication
In a wavelength control method for a communication system including a plurality of communication nodes performing communication in a communication system and a packet communication system, a communication node that is not performing reception in the wavelength multiplex communication system includes a wavelength tunable filter in a reception system as a wavelength controller. In the above
The wavelength arrangement of the wavelength multiplex communication system is detected, and the wavelength interval of the adjacent channel is set to a predetermined wavelength interval Δλ based on the wavelength of the channel at one end of the wavelength range of the wavelength multiplex communication system. When the transmission wavelength of the wavelength multiplex communication system of the communication node is controlled by a packet communication system ,
In both cases, light emission of a channel in the wavelength multiplex communication system is started or
After the light emission stops, the channel interval becomes the wavelength interval Δλ.
Until the light emission starts in the wavelength multiplex communication system until
Before receiving a channel or channel that has stopped emitting light
A wavelength control method, wherein one of the communication nodes serves as the wavelength controller. 2. A transmission interval of a wavelength control signal when a communication signal of the packet communication system for performing wavelength control (hereinafter, referred to as a wavelength control signal) is transmitted. wherein by shortening than the interval of transmission of the wavelength control signal, the wavelength control method according to claim 1, characterized in that the transition of the wavelength control role of. 3. A wavelength division multiplex communication system and said wavelength division multiplex communication.
A packet communication system independent of the wavelength multiplexing communication system.
It consists of multiple communication nodes that communicate with the
In the wavelength control method for a communication system to be formed, a communication node not receiving in the wavelength multiplex communication system
However, the wavelength tunable filter of the receiving system as a wavelength controller,
The wavelength arrangement of the wavelength multiplex communication system is detected, and the wavelength multiplex communication is performed.
Next to the channel wavelength at one end of the system wavelength range
The interval between the wavelengths of the adjacent channels is between preset wavelengths
The communication by the packet communication system so that the distance becomes Δλ.
Controlling the transmission wavelength of the wavelength multiplex communication system of the communication node; and
The transfer of the wavelength controller is performed by the packet communication system.
And a wavelength control method.