JP3397540B2 - WDM communication network - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication / optical network for exchanging information between a plurality of communication terminals using light, and more particularly to a communication capacity utilizing a plurality of light wavelengths. The present invention relates to a network for wavelength division multiplexing that greatly increases.

[0002]

2. Description of the Related Art A wavelength division multiplexing communication system utilizing an optical fiber has been proposed as a system for capturing a large amount of information such as moving images in a computer network, and an example using an optical LAN for optical wavelength division multiplexing communication (for example, electronic information). The publication OQE 91-126 of the Institute of Communication Engineers, "WDM composite optical LAN") has progressed as a reality, and development and research are rapidly progressing in response to the future multimedia era.

In such a wavelength division multiplex communication system, a plurality of wavelengths of optical wavelengths λa, λ1, λ2, ..., λn are used, and the optical wavelength λa communicates low-speed data and wavelength control information through an existing LAN. , Light wavelengths λ1, λ2, ..., λn
Provides wavelength independent communication services that are independent of speed. These light wavelengths λa and light wavelengths λ1, λ2, ..., λ
The signals of n are accommodated and communicated on one loop communication path. As the wavelength multiplexing method, wavelength division multiplexing access (DA-WDMA: DemandAssign) by demand assignment is used.
-Wavelength Division Multiple Access) is adopted, and when a request for high-speed communication or communication with long holding time occurs between certain nodes, a specific wavelength is assigned to the communication between the nodes and the Communication is performed by securing a line depending on the wavelength.

Such wavelength division multiple access (DA-
The WDMA) wavelength allocation method will be described in more detail with reference to FIGS. 12 and 13.

FIG. 12 is a node functional block diagram of a wavelength division multiplexing communication system. 901 receives a control signal λa and processes the signal by an existing LAN system, or converts data from an interface into a control signal λa and outputs it. A communication control circuit, 902 is a communication control circuit that mainly performs data communication in the DA-WDMA system, and 903 is a communication control circuit 90 for an existing LAN that receives a signal from a communication terminal (not shown).
1 or an interface circuit connected to the DA-WDMA communication control circuit 902, and 904 is each communication control circuit 9
A demultiplexer for demultiplexing into 01 and 902, a demultiplexer 905 for merging signals of the respective communication control circuits 901 and 902, and an optical communication path 910.

FIG. 13 is a diagram showing a network configuration of the wavelength division multiplex communication system, and 1001 is a control node for managing wavelengths used for communication by each node, and 1002.
Reference numerals 1005 to 1055 denote nodes as communication terminals for performing communication between the communication terminals, and the transmission line is shown as having a transmission path that makes one round in the arrow direction.

First, for example, from node 1003 to node 1
A method of transmitting high-speed data of a video signal to 005 will be described.

When the node 1003 requests transmission of high-speed data such as video from its own communication terminal (not shown), the interface circuit 903 sends a transmission request and a reception node information signal to the communication control circuit 901 of the existing LAN system. The communication control circuit 901 converts the information into an optical signal of wavelength λa and sends it out by one of existing LAN communication methods such as token passing, time division multiplexing (TDMA), and slotted loop. The optical signal of the wavelength λa is added to the multiplexer 905.
In one optical communication path and is output to the optical communication path 910, passes through the nodes 1004 and 1005, and passes through the control node 1
Reach 001.

The control node 1001 has a wavelength table and manages which node uses each wavelength in the transmission line.
Of the optical wavelengths λ1, λ2, ..., λn are assigned by the wavelength table when the node 1003 is not receiving, and the node 1003 communicates with the node 1005. Then, it prepares for reception, and then transmits a signal of transmission OK to the node 1003 to start transmission.

The signal of wavelength λa from the control node 1001 is received by the communication control circuit 901 of the node 1003,
Further, the signal is passed and enters the node 1005 by the existing LAN communication system of the wavelength λa, and the demultiplexer 9 of the node 1005
In 04, it is separated from the signals of other wavelengths and input to the communication control circuit 901. The communication control circuit 901 transmits the wavelength assigned to the DA-WDMA communication control circuit 902, and the node 1003 also transmits the DA-WDMA communication control circuit 9
02, the wavelength of the optical transmitter inside is set to the assigned wavelength, the video signal is transmitted from the node 1003 at the wavelength λm, for example, and the node 1005 filters the optical receiver inside the DA-WDMA communication control circuit 902. The wavelength of is set to the assigned wavelength λm, and the video signal from the node 1003 is received.

When the transmission from the node 1003 is completed,
The node 1003 outputs the wavelength λa carrying the transmission end code from the communication control circuit 901, notifies the control node 1001 of the transmission end, the control node 1001 updates the wavelength table, and the node 1005 cancels the filter setting. The communication ends.

The same applies to communication between other nodes, and the control node 1001 thus fulfills the function of always managing wavelength allocation.

[0013]

However, in a network in which a control node assigns wavelengths as in the above-mentioned conventional example, (1) the control node has a wide variety of functions, and therefore the control node has a plurality of configurations and is expensive. , It is not suitable for a small-scale network in terms of cost performance. (2) The procedure for establishing communication becomes complicated, and it takes time from the local node requesting communication establishment until the signal is actually transmitted. 3) If the control line is busy,
Even if there are unused wavelengths, a situation may occur in which communication cannot be established. (4) To allow a certain amount of difference between the wavelength allowed by the control node and the wavelength actually transmitted by the local node, the wavelength multiplexing number is set to You have to set less,
There was a problem.

An object of the present invention is to install a line monitoring node, which has a simple and inexpensive configuration for each node, does not require the above control node, shortens the time required to open a communication, and increases the transmission wavelength between local nodes. It is possible to increase the number of wavelength multiplexes by reducing the variation of the above, and to provide a wavelength multiplex network suitable for small-scale networks.

Another object of the present invention is to further shorten the time until the establishment of communication.

[0016]

To achieve the above object, the present invention installs a line monitoring node on a wavelength division multiplexing communication network, and the line monitoring node monitors wavelengths used in the network. , When an unused wavelength is detected, a signal notifying that it is unused is transmitted at that wavelength, and when a signal other than the signal transmitted at the same wavelength is detected, the transmission of the signal notifying that it is unused is terminated, and the other unused signals on the line are terminated. Search for the wavelength used.

When the local node desiring to transmit receives the signal indicating the unused state transmitted from the line monitoring node, it transmits the signal requesting the establishment of communication on the same wavelength and cannot receive the signal indicating the unused state. Alternatively, the receiving unit of the local node, which starts transmitting information after the signal collision is resolved, detects / monitors the wavelength of the signal notifying the unused state, and is transmitted from the transmitting node after the collision is resolved. If the desired signal is the desired signal, the signal is received. If the desired signal is not the desired signal, the wavelength of the signal newly transmitted from the line monitoring node and notifying the unused state is detected / monitored.

Specifically, the following inventions are provided to solve the above problems.

A line in a wavelength division multiplexing communication network
The line monitoring unit includes a monitoring unit and a local unit.
Send unused signals on the transmission line at unused wavelengths on the line
The local unit receives the unused signal after detecting the unused signal.
The transmission information signal is output at the used wavelength, and the line monitoring unit
Is the unused signal and the transmission information signal in the transmission line
Of the unused signal at the unused wavelength
It is characterized by stopping transmission .

The above-mentioned line monitoring unit independently operates as a line monitoring node.
May be located at the local node, wavelength
Unused wavelength signals can be configured with a simpler configuration than allocation control
Can be communicated to each local node. Also , since the local part only needs to satisfy a part of the configuration of the local node and sends back to other nodes with unused wavelengths, collisions and interference will occur at unused wavelengths. Since only unused wavelengths carrying information signals are carried, the wavelength of the own station can be easily secured with a simple configuration. Here, the line monitoring
Since we have clearly shown the relationship between the nodes and the local nodes,
Utilization of unused wavelengths increases new local nodes
Even if installed, it is necessary to receive a special wavelength assignment
Easy to detect unused wavelengths without other local
Information can be transmitted to the node.

In the above wavelength division multiplexing communication network,
The local unit detects an unused signal indicating unused from the unused wavelength from the line monitoring unit, and detects after the collision due to mixing of signals other than the unused signal is resolved in the unused wavelength. When the information signal is not addressed to itself, another unused wavelength is received from the line monitoring unit. When the signal after the collision / mixture is resolved is not addressed to the own station, the standby state is maintained at another unused wavelength according to the wavelength shift of the line monitoring node.

[0022]

In the above wavelength division multiplexing communication network,
The line monitoring unit merges a wavelength signal on the transmission line with a signal from an optical switch, a wavelength tunable filter that selects a specific signal from the output of the merger, and an output of the wavelength tunable filter. A light receiving circuit for receiving light, a signal generator for outputting an unused signal indicating unused, a wavelength tunable laser for converting the unused signal into a wavelength signal, and an output of the wavelength tunable laser through the transmission line or the above It is characterized by comprising the optical switch for switching to a merger, at least the wavelength tunable filter, and a control circuit for outputting a control signal to the wavelength tunable laser. The basic block configuration of the circuit monitoring node is shown to ensure a simple configuration.

In the above wavelength division multiplexing communication network,
The local unit includes a combiner for combining the wavelength signal on the transmission line and a signal from the optical switch, a wavelength tunable filter for selecting a specific signal from the output of the combiner, and an output of the wavelength tunable filter. A light receiving circuit for receiving light, a wavelength tunable laser for converting transmission information into the unused wavelength signal, an optical switch for switching the output of the wavelength tunable laser to the transmission line or the merger, and at least the wavelength tunable filter And a control circuit for outputting a control signal to the wavelength tunable laser. The configuration of the main block diagram of the local node is shown, and since the receiving unit can originally switch and use this light receiving circuit for transmission, the above is a configuration including the transmitting unit and the receiving unit,
It has a relatively simple structure.

In the above wavelength division multiplexing communication network,
The line monitoring unit includes a combiner for combining a wavelength signal on the transmission line and a signal from an optical switch, a demultiplexer for separating and outputting each wavelength from the output of the combiner, and a signal for each wavelength. A plurality of light receiving circuits for receiving light for each, a signal generator for outputting an unused signal indicating unused, a wavelength tunable laser for converting the unused signal into a wavelength signal, and an output of the wavelength tunable laser for the transmission line Alternatively, an optical switch for switching to the merger and a control circuit for outputting a control signal to at least the wavelength tunable laser are provided, and the plurality of light receiving circuits detect the unused wavelength signal. Here, if the light receiving circuit of the line monitoring node is provided by the number of wavelengths (the number of channels) that can be transmitted on the transmission line in the network, the tuning time can be reduced and the wavelength can be used without any idle time.

In the above wavelength division multiplexing communication network,
The local unit includes a combiner for combining the wavelength signal on the transmission line and a signal from the optical switch, a demultiplexer for separating and outputting each wavelength from the output of the combiner, and a signal for each wavelength. A plurality of light receiving circuits that receive light, a wavelength tunable laser that converts transmission information into the unused wavelength signal, an optical switch that switches the output of the wavelength tunable laser to the transmission line or the combiner, and at least the wavelength And a control circuit for outputting a control signal to the variable laser, wherein the plurality of light receiving circuits detect the unused wavelength signal. Also in this case, if multiple light receiving circuits are provided for the number of wavelengths (number of channels) that can be transmitted on the transmission line in the network, time-multiplexed wavelength multiplexing communication becomes possible.

In the above wavelength division multiplexing communication network,
The line monitoring unit scans a wavelength range in which the line can be specified by the wavelength tunable filter, detects the unused wavelength by comparing with pre-stored receivable wavelength signal data, and indicates the unused wavelength. It is characterized in that a used signal is output to the transmission line at the unused wavelength, and then the output of the unused wavelength is stopped when a signal collision due to a signal other than the unused signal is detected. . Here, the receivable wavelength signal data stored in advance, for example, if there is usable wavelength data scheduled on the network, and the relationship data between the control voltage to the wavelength tunable filter and the wavelength data,
The wavelength of the vacant channel can be easily detected by scanning the wavelength tunable filter.

In the above wavelength division multiplexing communication network,
The local section includes a combiner for combining the signal on the transmission line and a signal from the optical switch, a light receiving circuit for detecting a beat component from the output of the combiner, and a wavelength tunable device for converting a transmission signal into a wavelength signal. A wavelength of the wavelength tunable laser including a laser, an optical switch for switching the output of the wavelength tunable laser to the transmission line or the combiner, and a control circuit for controlling the wavelength of at least the wavelength signal of the wavelength tunable laser. Is detected and the unused wavelength signal is detected by the beat component output to the light receiving circuit. The unused wavelength is detected by using the beat component.

In the above wavelength division multiplexing communication network,
The line monitoring unit merges / branches a wavelength signal on the transmission line and a signal from an optical switch, and a wavelength tunable filter that selects at least two signals from branch outputs of the branch / merge unit, Light receiving circuits for receiving the outputs of the wavelength tunable filters, a signal generator for outputting an unused signal indicating unused, a wavelength tunable laser for converting the unused signal into a wavelength signal, and an output of the tunable laser To the transmission line or to the merger, and at least a wavelength tunable filter and a control circuit for outputting a control signal to the wavelength tunable laser, and a first unused wavelength on the transmission line. When you stop sending signals,
The second unused wavelength signal is output at another unused wavelength detected by the second tunable filter. Here, since two systems for detecting the unused wavelength are provided, the next unused wavelength can be transmitted as soon as the unused wavelength is started to be used by the local node, so that there is no time loss and efficient. Wavelength can be used.

The following effects can be obtained by the configurations / operations of the wavelength multiplexing network, line monitoring node, and local node described above.

(1) When establishing communication, it is not necessary to allocate wavelengths by the control node, nor is it necessary to exchange information by the control line. Therefore, it is possible to easily add nodes.

(2) Since the function of the line monitoring node is simple, it can be configured easily and inexpensively, so that it can be applied to a small-scale network.

(3) By tuning the wavelength used for transmission by each local node to the wavelength of the signal notifying that the line supervisory node transmits an unused signal, variation in wavelength between nodes is reduced and the number of wavelength division multiplexing is increased. it can.

(4) Since each local node can always know the wavelength to be used next, the time until the establishment of communication is shortened.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings together with each embodiment.

[First Embodiment] FIGS. 1, 2 and 5 are three simplified examples of the configuration of a line monitoring node used in the present invention, and FIGS. There are three types of simplified configuration examples of the local node, and FIGS. 7 and 8 are two simplified configuration examples of the wavelength division multiplexing network.

The present invention will be described below with reference to FIGS. 1, 3 and 7. FIG. 7 shows a system diagram of a tree-type network according to the present invention. In the figure, the second star couplers 51, 52, ... 5n and the line monitoring node 60 are connected with the star coupler 50 as the apex, and each second star coupler 5 is connected.
Local nodes # 1, # 2, ...
N is connected. In this tree network,
Although description will be made assuming that two optical fibers for transmission and reception are used as the transmission line, one optical fiber may be used and an optical branching / combining device may be provided at the input portion of each node. Further, in this tree-type network, based on the control signal of the line monitoring node 60, the local nodes # 1, # 2, ... #N communicate with each other to enable one-to-one or one-to-many communication. To do. Note that FIG. 8 shows an example of a star network, in which one of the star couplers 50 is a line monitoring node 60 and each local node # 1, # 2 ,.
#N is arranged, and signals from all nodes are immediately delivered to other nodes via a transmission path such as an optical fiber.

FIG. 1 shows a simplified block diagram of the line monitoring node 60 arranged in the highest hierarchy of the tree type network shown in FIG.

In FIG. 1, all wavelength-multiplexed signals on the line are connected via the star coupler 50 to the combiner 1.
01 is input. In the combiner 101, the optical signal of another node and the optical signal emitted from the own node are combined. Merger 10
The output of No. 1 is the wavelength tunable filter (Tu-FIL) 102.
, A desired one-wavelength optical signal is selected, converted into an electric signal by the light receiving circuit 103, and input to the control circuit (I) 104.

The electric signal generated by the pattern generator 105 passes through the drive circuit 106 and the wavelength tunable laser (T
It is converted into an optical signal by the u-LD) 107. On this occasion,
The transmission wavelength of the optical signal is determined by the control signal from the control circuit (I) 104. The optical signal is input to the transmission line by the optical switch 108, or output to the combiner 101 to be combined with the wavelength-multiplexed signal on the transmission line, and then the wavelength tunable filter 102 of the local station and the light receiving circuit. It is input to the control line (I) 104 via 103.

FIG. 3 is a simplified block diagram of a local node, and a plurality of local nodes are arranged in the tree network.

The local node can be functionally separated into a receiver and a transmitter. In FIG. 3, the receiving unit inputs all wavelength-multiplexed signals on a transmission line to a wavelength tunable filter (Tu-FIL) 302 via a branching device 301, selects a wavelength of a desired signal, and receives light. The circuit 303 converts the signal into an electric signal and outputs it to a communication terminal (not shown) connected to the local node.

The transmitting unit has almost the same configuration / action as that of the line monitoring node, and all the wavelength-multiplexed signals on the line via the branching device 301 and the optical signal emitted from the own node are combined by the combining device 304. Wavelength tunable filter (Tu-FI
L) 305, selects only a desired wavelength, converts it into an electric signal by the light receiving circuit 306, and then, the control circuit (III) 30
Input to 7. The control circuit (III) 307 exchanges control signals with a communication terminal (not shown).

An electric signal from a communication terminal (not shown) is
Tunable laser (Tu-LD) through the drive circuit 308
It is converted into an optical signal by 309. At this time, the control circuit
(III) The wavelength is determined by the control signal output from 307. The optical signal is a wavelength tunable laser (Tu-LD) 30.
It is input to the transmission line by the optical switch 310 via 9 or is output to the combiner 304.

Next, the detailed operation of the present invention will be described. The network shown in FIG. 7 is capable of wavelength division multiplex communication with a wavelength number δλ and a number of wavelengths n.
A case where (k ≦ n) is unused will be described as an example.

The line monitoring node 60 detects the unused wavelength λk existing on the line by scanning the wavelength of the wavelength tunable filter 102 over the wavelength range usable by the network, and the wavelength tunable filter is detected. The wavelength of 102 is set to λk.

Next, the electric signal S0 notifying that the pattern generator 105 is unused is input to the wavelength tunable laser 107 through the drive circuit 106 and converted into an optical signal. The wavelength λx of the output optical signal of the wavelength tunable laser 107
Is determined by the initial state of the line monitoring node 60, so that normally λx ≠ λk.

The optical signal is input by the optical switch 108 to the wavelength tunable filter 102 through the combiner 101. Since the wavelength of the wavelength tunable filter 102 is tuned to λk, the output is in the zero state.

In this state, the wavelength of the wavelength tunable filter 102 is fixed, a control signal is input from the control circuit (I) 104 to the drive circuit 106, the oscillation wavelength of the wavelength tunable laser 107 is scanned, and λx = When λk is reached (light receiving circuit 1
It is determined that the output changes from zero to a finite value from 03), the wavelength scanning of the oscillation wavelength of the wavelength tunable laser 107 is completed, and the optical switch 108 is switched to the transmission line side,
A signal Sk notifying that the signal is unused at the wavelength λk is output to the transmission optical fibers of the transmission line and transmitted from the star coupler 50 to the reception optical fibers of all the star couplers 51, 52, ... 5n.

As described above, the state in which the signal Sk notifying that the signal is unused at the wavelength λk exists on the network is maintained.

Next, a case will be described as an example where the local node # 3 which is not currently communicating transmits data to the local node # 5 which is not currently receiving.

First, in the local node # 3, a communication terminal (not shown) transmits a signal for establishing communication to the control circuit (III). Then, the control circuit (III) takes in all signals on the transmission line via the receiving optical fiber, the branching device 301, and the combiner 304, and the wavelength tunable filter 3
The filtered wavelength of No. 05 is scanned over the wavelength range that can be used by the wavelength tunable filter 305, converted into an electric signal by the light receiving circuit 306, and input to the control circuit (III) 307. In the control circuit (III) 307, the signal Sk notifying that the wavelength λk is unused is detected.
The wavelength of the wavelength tunable filter 305 is tuned to λk.

Next, the address signal Sa of the local node # 5 which is the transmission destination and is input from the communication terminal (not shown).
Is converted into an optical signal by the wavelength tunable laser 309 via the drive circuit 308. The wavelength λy of this optical signal is determined by the initial state of the local node, so that normally λy ≠ λk.

The optical signal of wavelength λy is transmitted to the multiplexer 304 side by the optical switch 310, merged with all the signals on the line including the signal Sk notifying the unused state, and input to the wavelength tunable filter 305. Since the wavelength of the wavelength tunable filter is tuned to λk, only the optical signal of the wavelength λk having the signal Sk indicating the unused state is received by the light receiving circuit 30.
6 is input.

Therefore, the control circuit (III) 307 sends a control signal to the drive circuit 308, and the drive circuit 308 scans the wavelength of the tunable laser 309 in accordance with the control signal.
When λy = λk (the signal Sk for notifying the light receiving circuit 306 and the address signal Sa of the local node # 5)
Is input at the same time, the signals collide / interfer with each other. Therefore, the optical switch 310 is switched to the transmission line side, and the address signal Sa of the local node # 5 is transmitted at the wavelength λk.
To the transmission line.

At the line monitoring node monitoring the transmission line, the wavelength of the wavelength tunable filter 102 is set to the wavelength λk, so that the line monitoring node of the own station has not transmitted from the signals on the line. Although the signal Sk indicating the use is received, when the local node # 3 starts transmitting the address signal Sa of the local node # 5 at the wavelength λk, the signal Sk and the signal Sa are transmitted at the wavelength λk of the optical signal on the transmission line. Cause a collision. When the line monitoring node detects a collision (generated by mixing signals other than the signal Sk indicating the unused state), the line monitoring node stops transmission of the optical signal of the wavelength λk having the signal Sk indicating the unused state, and transmits on the transmission line. To scan the other unused wavelengths. Therefore, the signal of wavelength λk on the transmission line is only the address signal of local node # 5. Then, in the line monitoring node, in the procedure described above,
The wavelength of the wavelength tunable filter 102 is scanned over the wavelength range usable by the network, an unused wavelength is detected, and the signal Sk is added to the unused wavelength and transmitted.

On the other hand, the local node which is not currently receiving always maintains the standby state.

The standby state means that the local node transmits data through the branching device 301 (for convenience, description will be made with reference to FIG. 3, but it is actually another local node connected to the network). A signal S that inputs the optical signal on the line to the wavelength tunable filter 302 of the receiving unit and notifies the unused signal transmitted from the line monitoring node from the optical signal on the transmission line
It is in a state of being tuned / received to the wavelength λk of k. When the local node is started up, it scans the wavelength tunable filter 302 of the receiving unit to receive the optical wavelength signal on the transmission line, confirms that there is no transmission signal addressed to itself, and confirms that it is unused. The wavelength λk of the notification signal Sk is detected, and then the standby state is maintained. Further, when the optical signal of the wavelength λk is used by another station, the wavelength tunable filter 3 of the receiver is again used.
02 is scanned to detect the optical signal of the signal Sk that the line supervisory node transmits next to notify the unused state, and the standby state is held.

Therefore, the wavelength of the wavelength tunable filter 302 of the receiving section of the local node # 5 is tuned to λk,
It is in a state of receiving the signal Sk indicating the unused state. When the local node # 3 starts transmitting the address signal Sa of the local node # 5, the signal of the wavelength λk causes a collision, but the line monitoring node stops transmitting the signal Sk indicating that it is not used. The optical signal of wavelength λk modulated by the address signal Sa of No. 5 remains.

Therefore, the signal received by the receiver of the local node # 5 changes from the signal Sk notifying that it is unused → collision → the address signal Sa of the local node # 5, and since the address is the own node, it is received as it is. By continuing the operation, the local node # 3 to the local node # 5
A communication to is established at wavelength λk.

Other than the local node # 5, the same operation is performed by the local node which is not currently receiving, but a collision /
Since the address of the signal after elimination of interference is not the local node of its own, the line monitoring node performs tuning / reception to detect an optical signal which is newly transmitted and notifies the unused state, and enters the next standby state.

In the above description, the only local node that accesses the optical signal wavelength λk of the signal Sk that notifies the unused signal transmitted by the line monitoring node and transmits the optical signal of wavelength λk is, but at the same time, a plurality of local nodes When the access is made, even if the line monitoring node stops the transmission of the signal Sk, the state in which the collision / interference is not resolved continues. In this case, all local nodes that are accessing the wavelength λk temporarily stop the access, and each local node generates a random number, as used in the electrical network such as Ethernet, and the random number is generated. After waiting a predetermined time based on the above, if there is no signal at the wavelength λk, the address signal of the transmission destination is transmitted.

If another local node first starts transmission and a signal already exists at the wavelength λk, the local node that wished to transmit the signal is next transmitted by the line monitoring node, or from now on. The optical signal wavelength of the signal Sk to be transmitted to notify the unused state is accessed.

The wavelength λk can be accessed again only to the local node that has accessed the signal Sk notifying that the signal is unused. Since no new local node has entered the collision processing routine, even if the line is congested, The transmission performance does not deteriorate due to the increase in the number of collisions.

In this embodiment, the line monitoring node is arranged at the top of the tree type network so that the latest information on the transmission line can be obtained quickly and the information placed on the transmission line reaches the local node. Since the time is shortened, the efficiency of the network is further improved.

[Second Embodiment] The second embodiment of the present invention is not a combination of a wavelength tunable filter (Tu-FIL) and a light receiving circuit as a means for selecting a specific wavelength from a wavelength division multiplexed signal, but a component. In this system, a plurality of light receiving circuits are provided and each light receiving circuit capable of receiving wavelengths of all channels that may exist in the transmission line is configured as a light receiving circuit array.

FIG. 2 shows, as an example of the present system, a simplified configuration when applied to a line monitoring node. The same functional units as those in FIG. 1 are designated by the same reference numerals, and overlapping description will be omitted. All the wavelength-multiplexed signals on the transmission line are taken in through the combiner 101 and the demultiplexer 202
After being separated into the respective wavelength components, the light receiving circuits corresponding to the respective wavelengths of the light receiving circuit array 203 convert the electric signals into electric signals and input them to the control circuit (II) 204.

FIG. 4 shows a simplified configuration of the present system when applied to the transmission unit of the local node. It should be noted that the same functional units as those in FIG. Here, all wavelength-multiplexed signals on the line are taken in through the branching device 301 and the combiner 304, separated by the demultiplexer 405 into respective wavelength components, and then the light receiving circuit array 40.
It is converted into an electric signal by the light receiving circuit corresponding to each wavelength of 6 and inputted to the control circuit (IV) 407. In this way, which light receiving circuit has no output is constantly and immediately detected, and the optical wavelength signal corresponding to the light receiving circuit is instructed to the drive signal 308 to output the cross signal of the wavelength not existing in the transmission line.

The feature of this embodiment is that all wavelength-multiplexed signals on the line can be monitored / detected at the same time. Therefore, as compared with the first embodiment, until an unused wavelength on the line is detected. Is shortened, and the time until the communication is opened is shortened accordingly.

[Third Embodiment] In the third embodiment of the present invention, the control circuit holds the wavelength control data of the wavelength tunable laser (Tu-LD), and the drive circuit is controlled based on this data. Then, light of a desired wavelength is obtained from the wavelength tunable laser.

As an example thereof, FIG. 5 shows a simplified configuration applied to a line monitoring node. The same functional units as those in FIG. 1 are designated by the same reference numerals, and overlapping description will be omitted. The difference from Fig. 1 is that the transmission line that captures signals on the line is
Since there is no combiner 101, there is no path for inputting the light of the wavelength tunable laser (Tu-LD) 107 of its own node to the wavelength tunable filter (Tu-FIL) 102 via the optical switch 108. With this configuration, an optical signal is received from the transmission line and converted into an electric signal by the light receiving circuit via the wavelength tunable filter 102. The wavelength tunable filter 102 is scanned to detect the wavelength of the optical signal existing at a predetermined wavelength interval. Detect and
Among the wavelengths of the optical signal data of the transmission line held by the control circuit (v), the wavelength in which the optical signal does not exist is found, and the control signal corresponding to the wavelength is output to the drive circuit 106. Signal Sk from the pattern generator 105 notifying that it is unused
Of the tunable wavelength laser 10 through the drive circuit 106.
The optical signal of unused wavelength is output from 7. The present configuration can also be applied to the transmission unit of the local node. In the local node, the optical wavelength having the signal Sk transmitted from the line monitoring node from the light receiving circuit is detected,
The control data of the optical wavelength of the optical signal data of the transmission line held by the control circuit (v ′) is supplied to the drive circuit 106, and the address signal of the local node to be communicated is included in the optical wavelength signal. To send.

Further, the above configuration can be applied as the configuration / control method of the wavelength tunable laser section of the line monitoring node or the local node described in the other embodiments.

The feature of the present embodiment is that the node configuration is simplified and the step of tuning the oscillation wavelength of the wavelength tunable laser to the wavelength of the wavelength tunable filter is unnecessary, so a signal notifying that the signal is not used and the destination The time required to transmit the address signal is shortened. However, the function of the control circuit becomes complicated, and it is necessary to allow variations in the oscillation wavelength among the local nodes.

[Fourth Embodiment] In the fourth embodiment of the present invention, in the transmitter of the local node, the wavelength of the wavelength tunable laser is tuned to the wavelength of a signal notifying that the line monitoring node is transmitting an unused signal. As a method of doing so, a beat signal corresponding to the wavelength difference between the signal notifying the unused state and the signal of the wavelength tunable laser generated by the combiner and the light receiving circuit is used.

FIG. 6 shows a schematic configuration of the applied local node.
Shown in. It should be noted that the same functional units as those in FIG. 3 are denoted by the same reference numerals, and overlapping description will be omitted.

In FIG. 6, the wavelength-multiplexed optical signal on the receiving optical fiber of the transmission line passes through the branching device 301, and is merged by the combining device 304 at the tunable laser 309 of its own node.
Is combined with the optical signal of and is converted into an electric signal by the light receiving circuit 306. In the light receiving circuit 306, the beat signal is obtained only when the wavelength-multiplexed optical signal and the wavelength of the optical signal of the wavelength tunable laser 309 approach each other.
If the wavelength is swept, a beat signal is obtained every time the wavelength of the wavelength tunable laser 309 approaches the wavelength of the wavelength-multiplexed optical signal.

The control circuit (VI) 608 detects the beat signal to detect the presence of a signal notifying that the signal is unused, and at the same time, the wavelength of the tunable laser 309 is tuned to the wavelength of the signal notifying that the signal is unused. Becomes

Therefore, the destination address signal is sent to the drive circuit 3
Via 08, it is converted into an optical signal by the wavelength tunable laser 309, the optical switch 310 is switched to the line side, and the address signal is placed on the line.

The feature of this embodiment is that since the wavelength tunable filter is not required in the transmitter of the local node, the configuration of the local node is simplified, and the signal notifying the unused state is transmitted from the wavelength multiplexed signals on the line. It is not necessary to scan the wavelength of the tunable filter for detection, and the time taken to tune the transmission wavelength to the wavelength of the signal indicating the unused state is shortened. On the other hand, the control circuit (VI) requires functions such as low-pass filter and beat signal detection.

[Fifth Embodiment] In the first to fourth embodiments described above, after the line monitoring node stops transmitting a signal notifying that the line is unused, an unused wavelength on the line is searched / detected to determine the wavelength. It operates to tune the oscillation wavelength of the tunable laser to an unused wavelength and send a signal indicating the next unused state.

Therefore, while the line monitoring node searches / detects an unused wavelength on the line and while tuning the oscillation wavelength of the wavelength tunable laser to the unused wavelength, the unused wavelength on the line remains unchanged. Even if it exists, there is no signal notifying that it is not used. Therefore, even if there is a node desiring to transmit, there is a time when it cannot be accessed.

In the present embodiment, while the line monitoring node is transmitting a signal notifying that it is unused, the next unused wavelength is searched / detected, and another wavelength variable light source is used next. By tuning to the wavelength, the purpose is to shorten the time when there is no signal indicating the unused state on the line and to shorten the waiting time of the node desiring to transmit.

In the configuration of this embodiment, the line monitoring node installed on the wavelength division multiplexing communication network has a plurality of line monitoring functions, and the first line monitoring function monitors the wavelengths used in the network. Then, when an unused wavelength is detected, a signal for making the wavelength unused is transmitted, and the second line monitoring function searches / detects another unused wavelength. Then, when the line monitoring node detects a signal other than the signal transmitted at the same wavelength as the signal notifying the unused state, the transmission of the signal notifying the unused state is terminated, and the unused wavelength detected at the second line monitoring function is not reached. In addition to transmitting the signal indicating the use, the first line monitoring function searches / detects another unused wavelength.

When the local node desiring to transmit receives the signal indicating the unused state transmitted from the line monitoring node, it transmits the signal requesting the establishment of communication at the same wavelength and cannot receive the signal indicating the unused state. Or, start transmitting information after the collision / interference is resolved.

The receiving unit of the local node which is not receiving is
After detecting / monitoring the wavelength of the signal notifying that the signal is unused, after collision / interference is resolved, the signal transmitted from the transmitting node is received if it is a desired signal, and if it is not a desired signal,
Detects / monitors the wavelength of a signal which is newly transmitted from the line monitoring node and reports the unused state.

By the configuration / operation of the wavelength multiplexing network, the line monitoring node, and the local node described above, the time during which there is no unused signal on the network is reduced, and the waiting time until the establishment of communication is greatly reduced.

The structure of this embodiment is the same as that shown in FIG. The basic operation in FIG. 2 is as described above. However, the operation of the line monitoring node is different. Hereinafter, in the tree type network of FIG. 7 and the star type network of FIG. 8, the case where the wavelength multiplex communication of the number of wavelengths n with the wavelength interval δλ is possible and the current λk1 (k1 ≦ n) is not used is described as an example. To do.

The line monitoring node shown in FIG. 2 takes in the wavelength-multiplexed signal on the network, separates it into wavelength components by the demultiplexer 202, and then uses the light receiving circuits corresponding to the respective wavelengths of the light receiving circuit array 203. It is detected that the wavelength λk1 is unused.

Next, the signal Sk notifying that the pattern generator 105 is not used is input to the wavelength tunable laser 107 through the drive circuit 106 and converted into an optical signal.
Since the wavelength λx1 of this optical signal depends on the initial state of the node, normally λx1 ≠ λk1. The optical signal is
The optical switch 108 allows the demultiplexer 2 through the combiner 101.
02, but since λx1 ≠ λk1, λk1
The output of the light receiving circuit of is in the zero state.

A control signal is input from the control circuit (I) 104 to the drive circuit 106 to scan the oscillation wavelength of the wavelength tunable laser 107, and when λx1 = λk1 (the output of the light receiving circuit of λk1 changes from zero to finite). The wavelength scanning of the wavelength tunable laser 107 is terminated, the optical switch 108 is switched to the line side, and the signal Sk indicating the unused state at the wavelength λk1 is transmitted to the transmission line.

As described above, the signal Sk for notifying the unused wavelength λk1 exists on the network. However, if another unused wavelength λk2 is generated in this state, the light receiving circuit array 203
The output of the light receiving circuit corresponding to the wavelength λk2 of 0 becomes zero, and it is detected that the wavelength λk2 is unused.

In this state, the case where the local node # 3 which is not currently communicating transmits data to the local node # 5 which is not currently receiving will be described as an example. Referring to FIG. 3, the transmission unit of the local node # 3 is
The wavelength tunable filter (Tu-FIL) 30 receives all signals on the line via the branching device 301 and the combiner 304.
5 and the light receiving circuit 306 detect the signal Sk notifying that the wavelength λk1 is unused, and tune the wavelength of the wavelength tunable filter 305 to λk1. Next, the wavelength tunable laser 30 receives the address signal Sa of the local node # 5, which is the transmission destination, input from the communication terminal (not shown) via the drive circuit 308.
The wavelength λy of this optical signal is determined by the initial state of the node, so normally λy ≠ λk.
It is 1. The optical signal having the wavelength λy passes through the combiner 304 by the optical switch 310, and the signal S notifying the unused state is transmitted.
All signals on the line including k are merged and input to the wavelength tunable filter 305. However, since the wavelength of the filter is tuned to λk, only the signal Sk notifying that the signal is unused is
It is input to the light receiving circuit 306.

Therefore, the control circuit (III) 307 sends a control signal to the drive circuit 308 to scan the wavelength of the wavelength tunable laser 309, and when λy = λk1 (light receiving circuit 30
6 is inputted at the same time as the signal Sk notifying that it is not used and the address signal Sa of the node # 5, so that the signals collide and interfere. Therefore, the optical switch 310 is switched to the line side and the local node # is transmitted at the wavelength λk1. The address signal Sa of No. 5 is transmitted to the line.

In this way, the light receiving circuit corresponding to the wavelength λk1 of the line monitoring node is supplied with the signal Sk transmitted from the own node and notifying that the line is unused, but the local node # 3 is the local node #. Address signal S of 5
When a is transmitted at the wavelength λk1, the signal S is transmitted on the line.
k and Sa cause collision / interference. When the line monitoring node detects a collision / interference (generated due to the presence of a signal other than the signal indicating the unused), the line monitoring node stops transmitting the signal Sk indicating the unused and the previously detected unused wavelength λk.
In step 2, the signal Sk indicating the unused state is transmitted according to the above-mentioned procedure, so that another local node # 6 desiring to transmit can start the work for transmission described in the local node # 3.

On the other hand, the other local nodes which are not currently receiving are always kept in the standby state and are kept in the state of being tuned / received to the wavelength λk1 of the signal Sk notifying that the signal is not used. Therefore, the signal received by the receiver of the local node # 5 is the signal Sk notifying that it is unused → collision / interference →
Since the address signal Sa of the local node # 5 has changed and the address is the own node, the reception continues as it is, and communication from the local node # 3 to the local node # 5 is established at the wavelength λk1. Other than the local node # 5, the local node that is not currently receiving the same operation also performs the same operation, but since the address of the signal after the collision / interference resolution is not its own node, the new line monitoring node is transmitting at the wavelength λk2. Communication with the local node # 6 is performed by performing tuning / reception to the signal Sk notifying of unused and if the address Sb of the signal transmitted from the local node # 6 at the wavelength λk2 is the own node, the reception is continued as it is. Is opened.

In this embodiment, by arranging the line monitoring node at the top of the tree type network, the latest information on the line can be quickly obtained, and the time until the information placed on the line reaches the local node. Since it becomes shorter, the efficiency of the network is further improved.

[Sixth Embodiment] In the present embodiment, the control circuit of the line monitoring node has the wavelength control data of the tunable laser, and a signal notifying that the signal is unused is detected during transmission.
By using this wavelength control data when tuning the wavelength of the tunable laser to the unused wavelength on the transmission line,
This shortens the time required for tuning. A combination of a wavelength tunable filter (Tu-FIL) and a light receiving circuit is used as a means for identifying an unused wavelength on a line from multiple signals while the line monitoring node is transmitting a signal notifying that the line is unused.

FIG. 9 shows a simplified configuration of the line monitoring node.
Shown in. The same functional units as those in FIG. 2 are designated by the same reference numerals, and duplicate description will be omitted. In FIG. 9, all wavelength-multiplexed signals on the transmission line are taken in via the branching / combining unit 201, and two wavelength tunable filters 210 and 211 are used.
Entered in.

First, when the wavelength of one wavelength tunable filter 210 is scanned and the unused wavelength λk1 is detected, the wavelength of the wavelength tunable laser 107 is tuned to λk1 by the same procedure as in the fifth embodiment, and the unused wavelength λk1 is used. The transmission of the signal Sk for notifying is started, and at the same time, the other wavelength tunable filter 211 starts searching for an unused wavelength on the line.

When a new unused wavelength λk2 is detected by the other wavelength tunable filter 211 and the light receiving circuit 221, it is held at the wavelength λk2 of the wavelength tunable filter 211 to inform the wavelength tunable laser 107 of the unused wavelength λk1. As soon as the signal transmission is completed, the tunable laser 107
Signal Sk indicating the unused state by tuning the wavelength of
Of the wavelength tunable filter 21 on the one hand
0 starts the search for unused wavelengths on the line.

Thus, as soon as the transmission of the unused wavelength λk1 is completed in the line monitoring node, the next unused wavelength λk is reached.
Since 2 can be transmitted, the unused search time can be shortened as much as possible.

[Seventh Embodiment] In the present embodiment, the signal gap time is used during transmission of a signal notifying the information necessary for tuning the tunable laser to the next unused wavelength. By collecting the signal, the tuning time of the wavelength of the tunable laser to the next unused wavelength is shortened after the transmission of the signal notifying the unused state is stopped.

In this embodiment, the line monitoring node has two wavelength tunable lasers (Tu-LD) 107 and 407, and a simplified configuration is shown in FIG. The same functional units as those in FIG. 2 are designated by the same reference numerals, and duplicate description will be omitted.

In FIG. 10, one wavelength tunable laser 1 is used.
While the signal 07 is transmitting the signal Sk indicating the unused at the unused wavelength λk1, the next unused wavelength λk2 is detected, and the transmission interval time of the signal Sk indicating the unused is used to utilize the other tunable laser 407. The wavelength is scanned, and the system waits in a state of being tuned to the wavelength λk2. Immediately after the transmission of the signal notifying that the wavelength λk1 is unused by one wavelength tunable laser 107, the other wavelength tunable laser 407 immediately transmits the signal notifying that the wavelength λk2 is not used.

In the above embodiment, an example having two sets of the wavelength tunable laser of the line monitoring node, the drive circuit, and the optical switch is shown. However, a plurality of wavelength tunable laser configurations are used and one wavelength tunable laser is used. While transmitting a signal notifying that the device is unused, the wavelengths of other wavelength tunable lasers are tuned to the next unused wavelength, and immediately after the transmission of the signal notifying the unused condition is stopped, the signal notifying the next unused condition is sent. By transmitting, the time required for tuning can be reduced.

In the fifth and sixth embodiments, since there is one tunable laser, the tunable laser is tuned to the next unused wavelength λk2 after the transmission of the signal Sk indicating the unused at the unused wavelength λk1 is completed. During this tuning time, since there is no signal indicating that the line is unused on the line, each local node becomes a waiting time. However, in this embodiment, if there is an unused wavelength on the line, a signal notifying that the wavelength is unused is transmitted at all times, and the utilization efficiency of the wavelength multiplexing line is greatly improved.

[Eighth Embodiment] In this embodiment, the first embodiment
In the seventh embodiment, each local node is configured to have two sets of wavelength detection / reception units, but with a simpler configuration, a function that improves the operation rate of the wavelength detection / reception units and improves cost performance is provided. An example provided is shown. The purpose of this embodiment is to detect a signal indicating that the local node is unused on the line, and perform wavelength detection / reception for setting the transmission wavelength to the unused wavelength and wavelength detection for receiving information from another node. / It is to be done by the receiving unit.

FIG. 11 shows a simplified block diagram of a local node according to this embodiment. In FIG. 11, the receiving unit passes all wavelength-multiplexed signals on the line via the combiner 304.
The signal is input to the wavelength tunable filter (Tu-FIL) 305, the wavelength of a desired signal is selected, converted into an electric signal by the light receiving circuit 306, and then input to the control circuit (IX) 311.
The control circuit (IX) exchanges signals with a communication terminal (not shown) connected to the node. A data signal from a communication terminal (not shown) passes through a drive circuit 308 via a control circuit (IX) 311 and a wavelength tunable laser (Tu-LD) 309.
Is converted into an optical signal by the control circuit (IX) 311.

The optical signal is input to the line by the optical switch 310, or is input to the control circuit (IX) 311 via the combiner 304, the wavelength tunable filter (Tu-FIL) 305, and the light receiving circuit 306.

Next, regarding the detailed operation of the present invention, in the network of FIG. 7, the case where wavelength multiplex communication of the number n of wavelengths at the wavelength interval δλ is possible and λk (k ≦ n) is not currently used is taken as an example. explain. The line monitoring node switches the optical switch 108 shown in FIG. 2 to the line side and transmits a signal Sk notifying that it is unused at an unused wavelength λk to the line. Thus
Signal Sk that informs the network of unused wavelength λk
Will exist.

Next, the local node # 3 currently not communicating is the local node # 3 currently not receiving.
5 will be described as an example.

The receiving unit of the local node # 3 is the combiner 3
04, all signals on the line are taken in, and the wavelength tunable filter (Tu-FIL) 305 and the light receiving circuit 306 detect the signal Sk indicating that the wavelength λk is not used, and the wavelength of the wavelength tunable filter 305 is set to λk. Synchronize. next,
Control circuit (IX) 311 allows communication terminal (not shown)
The address signal Sa of the local node # 5, which is the destination of the transmission, is converted into an optical signal by the wavelength tunable laser 309 via the drive circuit 308.
Normally depends on the initial state of the node, so
≠ λk.

The optical signal of wavelength λy passes through the combiner 304 by the optical switch 310 and is combined with all signals on the line including the signal Sk notifying that the signal is unused, and is input to the wavelength tunable filter 305. Since the wavelength of the filter is tuned to λk, only the signal Sk indicating the unused state is input to the light receiving circuit 306.

Therefore, the control circuit (IX) 311 sends a control signal to the driving circuit 308 to scan the wavelength of the wavelength tunable laser 309, and when λy = λk (light receiving circuit 306).
Since the signal Sk that informs the unused node and the address signal Sa of the local node # 5 are simultaneously input, the signals collide /
The optical switch 311 is switched to the line side, and the address signal Sa of the local node # 5 is transmitted to the transmission line at the wavelength λk.

On the other hand, in the receiving section of the local node # 3,
Information is obtained by receiving an address signal addressed to the own station on the transmission line. This state is similar to the standby state described above. Also, when there is a change to a new unused signal transmitted by the line monitoring node due to communication between other stations, the tuning / reception standby state is similarly performed.

With the configuration of the local node of this embodiment,
During reception, (1) transmission cannot be started or (2) reception of a signal notifying an unused wavelength cannot be received. However, it is possible to receive during transmission, and for a node with a relatively low access frequency Great effect.

[Ninth Embodiment] In the present embodiment, a line monitoring node having a simple and inexpensive structure is installed, so that a control line is not required, the time required for establishing communication is shortened, and a local node is provided. (EN) Provided is a communication method suitable for obtaining information possessed by terminals connected to other nodes in a wavelength multiplexing network suitable for small-scale networks by increasing the number of wavelength multiplexes by reducing variations in transmission wavelengths between them.

In this embodiment, a line monitoring node is installed on the wavelength division multiplexing communication network, and this line monitoring node is
The wavelength used in the network is monitored, and when an unused wavelength is detected, a signal notifying that the signal is unused is transmitted, and when a signal other than the signal transmitted at the same wavelength is detected, the signal notifying that the signal is unused Finish sending,
Search for other unused wavelengths on the line. A node desiring to receive information owned by a terminal connected to another node receives a signal notifying that the circuit monitoring node transmits an unused signal, and transmits a signal requesting transmission of information at the same wavelength,
After the collision with the signal notifying the unused state is resolved, when the collision is detected again, the transmission of the signal requesting the transmission of the information is stopped and the information transmitted from another node is received. In addition, each local node that is not receiving is detecting / monitoring the wavelength of the signal notifying that it is unused, and after the first collision is resolved, if the signal is a signal requesting transmission to the own node, After transmitting the transmission start signal at the same wavelength, the requested information is transmitted. If the signal received after the first collision has been resolved is not the signal addressed to the own node, a signal newly transmitted from the circuit monitoring node indicating the unused state is detected / monitored.

Specific examples are as follows. This will be described with reference to the network system diagrams of FIGS. 7 and 8 described above, the block diagram of the line monitoring node of FIG. 1 and the block diagram of the local node of FIG. Note that the configuration of each block is omitted because it overlaps with the above description.

The operation of this embodiment will be described. Figure 7
In this network, the number of wavelengths n wavelength multiplex communication is possible at the wavelength interval δλ, and the case where the current λk (k ≦ n) is unused is taken as an example.
It is assumed that k is output to the transmission line at the wavelength λk. In this case, the wavelength tunable filter 102 and the wavelength tunable laser 107 of the line monitoring node are set to the wavelength λk.

Next, a case will be described as an example where the local node # 3 which is not currently transmitting and receiving acquires the data possessed by the terminal connected to the local node # 5 which is not currently transmitting and receiving.

The transmitter of the local node # 3 is the branch unit 3
01, all signals on the line are taken in via the combiner 304, and the signal S that informs the unused of the wavelength λk by the wavelength tunable filter (Tu-FIL) 305 and the light receiving circuit 306.
k is detected, and the wavelength of the variable wavelength filter 305 is tuned to λk. Then, the transmission signal Sc including the address of the local node # 5 and the information about the data desired to be obtained from the communication terminal (not shown) is converted into an optical signal by the wavelength tunable laser 309 via the drive circuit 308. Since the wavelength λz of this optical signal is determined by the initial state of the node, normally λz ≠ λk.

At the local node # 3, the optical signal of wavelength λz passes through the combiner 304 by the optical switch 310,
All signals on the line including the unused signal Sk are merged and input to the tunable filter 305. Since the wavelength of the filter is tuned to λk, only the unused signal Sk is It is input to the light receiving circuit 306.

Therefore, the control circuit (III) 307 sends a control signal to the drive circuit 308 to scan the wavelength of the wavelength tunable laser 309, and when λy = λk (light receiving circuit 306).
Since the signal Sk notifying that the signal is not used and the transmission signal Sc to the local node # 5 are simultaneously input, the signals collide, so that it is possible to determine). To the line.

In the line monitoring node, the tunable filter 1
Since the wavelength 02 is set to λk, the unused signal Sk transmitted from the local node is received from the signals on the line, but the local node # 3 transfers to the local node # 5. When the transmission signal Sc of No. 1 is transmitted at the wavelength λk, the signals Sk and Sc collide on the transmission line. When the line monitoring node detects a collision (generated due to the presence of a signal other than the signal indicating unused), the line monitoring node stops the transmission of the signal Sk indicating the unused at the wavelength λk, and the other unused lines on the line. The wavelength investigation is started. Therefore, the signal of wavelength λk on the transmission line is the local node #
Only the transmission signal from 3 to the local node # 5.

On the other hand, the local node that is not currently receiving always maintains the standby state. This standby state generally means that the local node inputs the signal on the transmission line to the wavelength tunable filter 302 of the receiving unit via the branching device 301 (shown in FIG. 3) and selects the line monitoring node from the signals on the transmission line. Is in the state of being tuned / received to the wavelength λk of the signal Sk which notifies that the signal is unused.

Therefore, the wavelength of the wavelength tunable filter 302 of the receiver of the local node # 5 is tuned to λk, and the signal Sk notifying that the signal is unused is being received. When the local node # 3 starts transmitting the transmission signal Sc to the local node # 5, the signal of the wavelength λk collides, but the line monitoring node stops transmitting the wavelength λk of the signal Sk notifying that the signal is unused. The transmission signal Sc to the local node # 5 remains. Therefore, the signal received by the receiver of the local node # 5 is the signal Sk →
Collision → Change to the transmission signal Sc to the local node # 5,
Since the address signal of the transmission signal Sc is its own node, the wavelength of the wavelength tunable laser (309) of the transmitter is tuned to λk (for tuning to the wavelength λk, the local node # 3 is a wavelength tunable laser of the transmitter). Description is omitted because it is the same as the tuning operation to the wavelength λk of the signal notifying that the line monitoring node transmits an unused signal).) After transmitting the transmission start signal to the local node # 3 at the wavelength λk, Start sending the requested data.

When the local node # 5 transmits a message with the wavelength λk, the signal of the wavelength λk temporarily collides, but the receiver of the local node # 3 receives the wavelength λk, and when this collision is detected, Collision is resolved by stopping the transmission at the wavelength λk, and the data of the transmission signal of the wavelength λk transmitted by the local node # 5 is received.

By the above operation, the terminal connected to the local node # 3 can obtain the data owned by the terminal connected to the local node # 5.

On the other hand, when the local node # 3 cannot detect the collision of the transmission signal Sc to the local node # 5 for a certain period of time (the situation where the local node # 5 cannot transmit the requested data due to communication with other terminals). ), The transmission of the transmission signal Sc is stopped, the wavelength λk is put into an unused state, and the same procedure is repeated on another occasion.

Other than the local node # 5, the same operation is performed by the local node which is not currently receiving. However, since the address of the signal after the conflict resolution due to the transmission stop of the line monitoring node is not the own node, the reception wavelength is changed from λk. Next, the signal notifying the new unused signal transmitted from the line monitoring node is tuned / received to the wavelength, and the next standby state is set.

In the above, only one local node has accessed the signal Sk indicating that the circuit monitoring node transmits an unused signal. However, when a plurality of local nodes simultaneously access, the circuit monitoring node transmits the signal Sk. Even if it stops, the collision will not be resolved.
In this case, all local nodes accessing the wavelength λk, such as those used in the electrical network such as Ethernet, temporarily stop the access, and each local node generates a random number. After waiting a time based on the above, if there is no signal at the wavelength λk, transmission is started.

If a signal already exists at the wavelength λk, the local node sends a signal Sk indicating that the line supervisory node is transmitting or will transmit from now on.
To access.

The wavelength λk can be re-accessed only to the local node that has accessed the signal Sk notifying that the signal is not used. Since no new local node has entered the collision processing routine, the line is congested. ,
The transmission performance does not deteriorate due to the increase in the number of collisions.

In this embodiment, by arranging the line monitoring node shown in FIG. 7 at the top of the tree type network, the latest information on the line can be quickly obtained and the information put on the transmission line can be transmitted to the local node. Since the time to reach is shortened, the efficiency of the network is further improved.

Not limited to this embodiment, as a corresponding configuration when a third party local node requests information transmission, (1) a wavelength tunable filter as a means for selecting a specific wavelength from wavelength multiplexed signals. (Tu-FIL) not using a combination of a light receiving circuit, but using a demultiplexer and a light receiving circuit array, (2) As described with reference to FIG. The wavelength control data is held in the control circuit, the drive circuit is controlled based on this control data, and the light of the desired wavelength is obtained from the tunable laser.
(3) As described with reference to FIG. 6 described above, in the transmitter of the local node, as a means for tuning the wavelength of the wavelength tunable laser to the wavelength of the signal notifying that it is unused, which is being transmitted by the line monitoring node, A configuration may be adopted in which a beat signal corresponding to the wavelength difference between the signal notifying that the signal is not used and the signal of the wavelength tunable laser generated by the optical device and the light receiving circuit is used.

With the configuration / operation of the wavelength division multiplexing network, the line monitoring node, and the local node, the information owned by the terminal connected to the network can be easily obtained by the terminal connected to any local node.

[0138]

As described above, according to the present invention, in the wavelength multiplex communication network, (1) in the wavelength multiplex communication network, the function is simple and the configuration is simple instead of the control node for allocating wavelengths. By installing an inexpensive line monitoring node, it is suitable not only for large-scale networks but also for small-scale networks, and it has become possible to easily add local nodes.
(2) The procedure for establishing communication is simple, and since each local node can know the wavelength to be used next, the time from the local node requesting communication establishment until the signal is actually transmitted. (3) Since the information exchange by the control line is not required at the time of communication opening, it is possible to coexist on the same network without burdening the wavelength allocation method and the control and control line by the control node.
(4) By tuning the wavelength used for transmission by each local node to the wavelength of a signal notifying that the line monitoring node transmits an unused signal, variation in wavelength between nodes can be reduced and the number of wavelength division multiplexing can be increased. Results in a significant improvement.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a line monitoring node according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a line monitoring node according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a local node according to an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a local node according to an embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a line monitoring node according to an embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a local node according to an embodiment of the present invention.

FIG. 7 is a schematic diagram of a tree type wavelength division multiplexing communication network to which the present invention is applied.

FIG. 8 is a schematic diagram of a star type wavelength division multiplexing communication network to which the present invention is applied.

FIG. 9 is a schematic configuration diagram of a line monitoring node according to an embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of a line monitoring node according to an embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of a local node according to an embodiment of the present invention.

FIG. 12 is a functional block diagram of a node of a conventional example.

FIG. 13 is a block diagram of a conventional ring network.

[Explanation of symbols]

101,304 merger 102, 302, 305 Wavelength variable filter 103, 303, 306 Light receiving circuit 104, 204, 307, 407, 504 Control circuit 105 pattern generator 106, 308 drive circuit 107,309 Tunable laser 108,310,508 Optical switch 202,405 duplexer 203,406 Light receiving circuit array

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14/00-14/08 H04L 12/44

Claims (11)

(57) [Claims] 1. A wavelength division multiplexing communication network comprising a line monitoring unit and a local unit, wherein the line monitoring unit is unused at unused wavelengths in a transmission line.
A signal is transmitted on the transmission line, and the local unit detects the unused signal and then
Output the transmission information signal, and the line monitoring unit outputs the transmission information signal.
Collision between the unused signal and the transmission information signal on the transmission line
When detected, it stops transmission of unused signal at the unused wavelength.
WDM network characterized by stopping . 2. The local unit detects the unused signal from the line monitoring unit, and when the information signal detected after the collision due to mixing of signals other than the unused signal is resolved is not addressed to the own station, The wavelength multiplexing communication network according to claim 1, wherein another unused wavelength is received from the line monitoring unit. 3. The line monitoring unit merges a wavelength signal on the transmission line with a signal from an optical switch, and
A wavelength tunable filter that selects a specific wavelength from the output of the merger, a light receiving circuit that receives the output of the wavelength tunable filter, and a signal generator that outputs an unused signal indicating unused
A wavelength tunable laser that converts the unused signal into a wavelength signal, an optical switch that switches the output of the wavelength tunable laser to the transmission line or the merger, at least the wavelength tunable filter and a control signal to the tunable laser. The wavelength multiplexing communication network according to claim 1, further comprising: 4. The combiner for combining the wavelength signal on the transmission line and the signal from the optical switch in the local unit,
A wavelength tunable filter that selects a specific signal from the output of the combiner, a light receiving circuit that receives the output of the wavelength tunable filter, a wavelength tunable laser that converts a transmission information signal into the unused wavelength signal, and the wavelength and the optical switch for switching the output of the tunable laser to the transmission line or the merging unit, at least the wavelength tunable filter and the tunable laser to output a control signal controlling circuit and to which claim 1 Symbol for comprising a
The WDM communication network listed . 5. The line monitoring unit merges a wavelength signal on the transmission line with a signal from an optical switch, and
A demultiplexer that simultaneously separates and outputs each wavelength from the output of the combiner, and a plurality of light receiving circuits that receive light for each signal of each wavelength,
A signal generator that outputs an unused signal indicating unused, a wavelength tunable laser that converts the wavelength signal of the unused signal, and an optical switch that switches the output of the wavelength tunable laser to the transmission line or the merger. , and a control circuit for outputting a control signal to at least the wavelength tunable laser, the plurality of light receiving circuit detects a wavelength signal of the unused claim 1
WDM communication network described . 6. The combiner for combining the wavelength signal on the transmission line and the signal from the optical switch in the local unit,
A demultiplexer that simultaneously separates and outputs each wavelength from the output of the combiner, a plurality of light receiving circuits that receive each wavelength, a wavelength tunable laser that converts a transmission information signal to the unused wavelength, and the wavelength An optical switch for switching the output of the tunable laser to the transmission line or the combiner, and a control circuit for outputting a control signal to at least the tunable laser, and the plurality of light receiving circuits detect the unused wavelength signal Contract
The wavelength division multiplexing communication network according to claim 1. 7. The line monitoring unit scans a wavelength range in which a line can be used by a wavelength tunable filter, compares the wavelength range with receivable wavelength signal data stored in advance, and detects the unused wavelength, An unused signal indicating unused at the unused wavelength is output to the transmission line, and when a signal collision due to a signal other than the unused signal is detected, the output of the unused wavelength is stopped. The wavelength division multiplexing communication network according to claim 1 . 8. The local unit includes a combiner for combining a signal on the transmission line and a signal from an optical switch, a light receiving circuit for detecting a beat component from an output of the combiner, and a transmission signal for modulation. A wavelength tunable laser that outputs a wavelength signal, an optical switch that switches the output of the wavelength tunable laser to the transmission line or the merger, and a control circuit that controls at least the wavelength of the wavelength signal of the tunable laser. 2. The wavelength division multiplexing communication network according to claim 1 , further comprising: scanning the wavelength of the wavelength tunable laser to detect the unused wavelength signal by the beat component output to the light receiving circuit. 9. The line monitoring unit selects at least two signals from a branch / merge device that joins / branches a wavelength signal on the transmission line and a signal from an optical switch, and at least two signals from a branch output of the branch / merge device. A wavelength tunable filter, a light receiving circuit for receiving the output of each wavelength tunable filter, a signal generator for outputting an unused signal indicating unused, a wavelength tunable laser for converting the unused signal into a wavelength signal, The optical switch for switching the output of the wavelength tunable laser to the transmission line or to the merger side, at least the wavelength tunable filter and a control circuit for outputting a control signal to the tunable laser, The wave according to claim 1 , wherein when the transmission of one unused wavelength signal is stopped, the second unused wavelength signal is output at another unused wavelength detected by the second wavelength tunable filter. Long multiplex communication network. 10. A wavelength division multiplexing communications network according to any one of claims 1 to 9, wherein the line monitoring portion of at least one, the local unit is a plurality, wherein the network star or tree Type WDM network. 11. A network equipped with a line monitoring unit and a local unit.
A WDM communication method on network, The line monitoring unit is unused at unused wavelengths on the transmission line.
Send a signal on the transmission line, The local unit detects the unused signal and then
The transmission information signal is output at a long length, and then the line monitoring unit
The unused signal and the transmission information signal on the transmission line
Of the unused signal at the unused wavelength
A wavelength division multiplexing method characterized by stopping transmission.