JP3052452B2 - Time Division Multiplexing / Optical Wavelength Division Multiplexing Hybrid Transmission System and Node Equipment for Optical Local Area Network System - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system and a node device in an optical local area network (LAN) system for performing time division multiplexing and optical wavelength division multiplexing combined transmission.

[0002]

2. Description of the Related Art Conventional optical wavelength division multiplexing transmission using light L
In the AN system, as shown in FIG. 6A, each node has the same number of electrical wavelengths as the number of optical wavelengths used for optical wavelength division multiplex transmission.
It has an optical converter, an optical-electrical converter, and an optical filter, and performs optical-electrical conversion and electric-optical conversion for all optical wavelengths used in each node. As for media access control, a method is employed in which an access processing circuit in each node reads and writes a header portion (FIG. 6B) in a packet in which addresses of transmission / reception nodes are written, and performs routing processing of the packet. ing.

[0003]

SUMMARY OF THE INVENTION The above-mentioned conventional optical LA
In the optical wavelength division multiplexing transmission system of the N system, in order to perform optical-to-electrical conversion and electrical-to-optical conversion of all optical wavelengths in each node, the nodes are required to carry out electrical-to-electrical conversion for all optical wavelengths used in the system.
The necessity of having an optical converter, an optical-electrical converter and an optical filter increases costs. This limits the need to increase the number of optical wavelengths used in the system to improve the throughput of the system. Further, since it is necessary to simultaneously perform access processing for signals transmitted at each optical wavelength, there is a disadvantage that an access processing circuit in a node becomes complicated.

[0004]

In the time division multiplexing / wavelength division multiplexing composite transmission system of the optical LAN system according to the present invention, a unique optical wavelength is assigned in advance to each node as an address, and the transmitting node is assigned to the receiving node. At the optical wavelength corresponding to the address, for the transmitting node or for the optical wavelength output by the transmitting node, data is transmitted within the assigned time slot, and at the receiving node, a plurality of optical wavelengths input from the input terminal are transmitted. The optical wavelength selection switch having a function of outputting only a specific optical wavelength to the second output terminal and outputting other optical wavelengths to the first output terminal receives only the optical wavelength addressed to the receiving node. It is characterized by performing time-division multiplexing / optical wavelength-division multiplexing composite data transmission in which other optical wavelengths are passed as they are.

[0005] Further, the node device of the present invention, in order to realize the above time division multiplexing / optical wavelength division multiplexing composite transmission, has an optical wavelength selective switch, a data interface circuit, a frame pulse receiving circuit, a control circuit, an optical delay line, and an optical delay line. 7. It has a splitter, one or two optical multiplexers, two or more electro-optical converters, and two optical-electric converters, and has the structure shown in claim 5 or 6. Features.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings. FIGS. 1 and 2 show the time division multiplexing / multiplexing of the optical LAN system of the present invention.
It is a diagram showing a data transmission method of optical wavelength division multiplexing composite,
3 and 4 are diagrams showing the configuration of the node device according to the present invention.

As shown in FIG. 3, a node device according to a fifth aspect of the present invention includes a frame pulse receiving circuit 6 for receiving a frame pulse and generating data transmission timing in the node. The first optical-electrical converter 9 and the first electrical-optical converter 11 connected to the first optical fiber transmission line 13 for transmitting the frame pulse, A data interface circuit 5 that outputs to the plurality of second electro-optical converter groups 12 in response to the timing signal from the pulse receiving circuit 6 and sends out data from the second electro-optical converter group 12 to a device outside the node; A first output terminal having a function of outputting only a specific light wavelength of a plurality of light wavelengths input from the input terminal to the second output terminal and outputting other light wavelengths to the first output terminal. The terminal is connected to a second optical fiber transmission line 14 for performing optical wavelength division multiplexing transmission, the second output terminal is connected to the second optical-electrical converter 10, and the input terminal is connected to the output terminal of the optical multiplexer 7. Optical wavelength selection switch 4 connected
And converting the optical signal from the second output terminal of the optical wavelength selective switch 4 into an electric signal,
And a plurality of second electro-optical converters that convert all of the plurality of electric signal data from the data interface circuit 5 into a plurality of optical signals of different wavelengths and output the converted signals. A converter group 12, a plurality of input terminals and one
One output terminal is connected to the input terminal of the wavelength selection switch 4 and one of the plurality of input terminals is connected to the optical delay line 8.
And the other input terminal is connected to the optical output terminal of the second electro-optical converter group 12;
And an optical delay line 8 whose input is connected to the input end of the second optical fiber transmission line 14.

As shown in FIG. 4, the node device according to the sixth aspect has a single optical fiber transmission line for branching an optical wavelength for transmitting a frame pulse to an input portion of the node and another optical wavelength. The optical splitter 19 includes a first multiplexer 17 for multiplexing an optical wavelength for transmitting a frame pulse to an output unit and another optical wavelength, and a frame pulse receiving circuit 6 and a frame pulse receiving circuit A first light-to-electricity converter 9 and a first light-to-electricity converter 11 connected to 6;
The data sent from the device outside the node is output to the second electro-optical converter 16 having the variable optical wavelength light source in accordance with the timing signal from the frame pulse receiving circuit 6, and is output from the second optical-electric converter 10. A data interface circuit 5 for sending data to an external device; an optical wavelength selective switch 4 having a first output terminal connected to the second input terminal of the first optical multiplexer 17; The second optical-to-electrical converter 10 converts an optical signal from the output terminal 2 into an electric signal and outputs the electric signal to the data interface circuit 5, and converts the electric signal data from the data interface circuit 5 into an optical signal and outputs the same. A second electro-optical converter 16 having a tunable wavelength light source, a first input terminal connected to the optical output terminal of the second electro-optical converter 16, and a second input terminal connected to the output of the optical delay line 8; Connected to The output optical wavelength of the second electro-optical converter 16 is controlled by the second optical multiplexer 18 whose output terminal is connected to the input terminal of the wavelength selective switch 4 and the receiving node address information from the data interface circuit 5. And a control circuit 15.

As the optical wavelength selection switch 4 used here, "1989 European Conference On Optical C"
"Variable wavelength optical filter using acousto-optic effect" described in "Ommunication Proceedings", Vol. 3, paragraphs 70-73. As shown in FIG. 5, a variable wavelength optical filter using the acousto-optic effect has two optical waveguides 25 formed by diffusing titanium on a lithium niobate substrate, and first and second TE-TMs. Splitter 26, 2
7, an electrode 28 and an acoustic wave region 29. First
The optical signal input from the input terminal 21 of the first TE-T
The light is separated into TE polarized light and TM polarized light by the M splitter 26, travels separately through the two waveguides 25, is multiplexed by the second TE-TM splitter 27, and is output to the first output terminal 23.
At this time, when an electric signal of a certain frequency is input to the electrode, an optical signal of a wavelength corresponding to the frequency is subjected to TE-TM mode conversion by an acousto-optic effect on the optical waveguide 25 in the acoustic wave region 29, so that the light of the wavelength Only the signal is output to the second output terminal 24, and the optical signals of other wavelengths are output to the first output terminal 23. The wavelength of the light output to the second output terminal 24 can be changed by changing the frequency of the electric signal. Similarly, the optical signal input from the second input terminal 22 is output to the second output terminal 24 when the electric signal is not input to the electrode, and the electric signal of a certain frequency is input to the electrode. Sometimes, only the optical signal of a certain wavelength corresponding to the frequency is output to the first output terminal 23, and the optical signals of other wavelengths are output to the second output terminal 24. When this is used as an optical wavelength selection switch, the frequency of an applied electric signal is fixed, and the first input terminal 21 is used as an input terminal.

Next, an optical LAN according to the present invention will be described with reference to FIGS.
An optical wavelength division multiplexing data transmission system of the system will be described. As shown in FIGS. 1 and 2, the data transmission mode in the optical LAN system of the present invention is such that a fixed-length data packet transmitted at a plurality of different optical wavelengths is transmitted in a time slot delimited by a frame pulse. Transmitted. Here, all the optical wavelengths correspond one-to-one with the addresses of all the nodes in the system, and when the transmitted optical wavelength arrives at the corresponding node, it is pulled into the node and received. It is not transmitted to the next connected node. 1 and 2 show the optical wavelength λ transmitted to the node N.
N is received by node N.

As for data transmission, as shown in FIG. 1, when a certain node (in this case, node 2) transmits data, it is assigned to the node, that is, only that node transmits data. Data is transmitted at an optical wavelength corresponding to the receiving node within a possible time slot (time slot 2). At this time, it is possible to simultaneously transmit data to a plurality of nodes using a plurality of electro-optical converters having different output light wavelengths (claim 1).

Alternatively, as shown in FIG. 2, when a certain node transmits data, the data is transmitted within a time slot (node 1) assigned to the optical wavelength output by that node.
Λ2, time slot 3 for λ3, time slot 4 for λ4, and time slot 4 for λ3 of node 2) at the optical wavelength corresponding to the receiving node. (Claim 2).

Here, the frame pulse transmission method includes a method of transmitting data using an optical fiber transmission line different from an optical fiber transmission line for performing data transmission (claim 3), and a method of transmitting an optical fiber transmission line for performing data transmission. There is a method of transmitting data at a different optical wavelength from a plurality of optical wavelengths used for data transmission in the same optical fiber transmission line as the transmission line.

Further, a detailed data transmission / reception operation of the node will be described. The method according to claim 1, wherein the node device shown in FIG. 3 is used, and when the node transmits data, the data interface circuit 5 which receives data to be transmitted to another node from the external device transmits the data to the node to which the data should be transmitted. The address light wavelength is checked, and a device capable of transmitting the light wavelength is selected from the plurality of second electro-optical converter groups 12 to prepare for transmitting data thereto. The frame pulse receiving circuit 6 sends a signal to the data interface circuit 5 when receiving a time slot allocated to this node (at this time, an external device transmits a data interface until the time slot is received). When data addressed to another node is sent to the circuit 5, the data interface circuit 5 prepares to send data to any of the plurality of second electro-optical converter groups 12 in the same procedure as described above. I do). The data interface circuit 5 uses the timing signal sent from the frame pulse receiving circuit 6 to adjust all the data ready for transmission to the plurality of second electro-optical converters in accordance with the timing of the time slot. And the second group of electro-optical converters 12
The data converted into the optical signal of the optical wavelength by the optical fiber transmission path 1
4 is sent out.

According to the second aspect of the present invention, when the node transmits data using the node device shown in FIG. 4, the data interface circuit 5 which receives data to be transmitted to another node from an external device, The address light wavelength of the node to which data is to be transmitted is confirmed, and a control signal is sent to the second electro-optical converter 16 having a variable wavelength light source through the control circuit 15 so that data can be transmitted at the light wavelength. (At this point, no signal is sent yet). When the node receives a time slot allocated for transmitting data at the optical wavelength, the frame pulse receiving circuit 6
, And the data interface circuit 5 uses the timing signal sent from the frame pulse receiving circuit 6 to match the timing of the time slot with the second electric signal.
Data is sent to the optical converter 16 and the second electro-optical converter 1
The data converted into the optical signal of the optical wavelength by the optical fiber 6 is transmitted to the optical fiber transmission line 17 through the wavelength selective switch 4.

When the node receives data, each node outputs only the optical wavelength assigned as the address of its own node among the optical wavelengths previously input from the input terminal of the optical wavelength selective switch 4 to the second output terminal. It is set so as to output to the terminal and output the other light wavelengths to the first output terminal. As a result, only the data sent to the node out of all the optical wavelengths existing on the time slot arriving at the node is received by the optical wavelength selective switch 4, and the second optical-electrical converter 10 The data is sent out to the external device through the interface circuit 5.

[0017]

As described above, the optical LAN of the present invention
In the time division multiplexing / wavelength division multiplexing composite transmission system of the system, a unique optical wavelength is assigned as an address to each node in advance, and the transmitting node transmits to the transmitting node with an optical wavelength corresponding to the address of the receiving node. For the optical wavelength output by the transmitting node, data is transmitted within the assigned time slot. The receiving node receives only the optical wavelength addressed to the receiving node by the optical wavelength selection switch, and the other optical wavelengths are the optical signal. Even if the number of wavelengths of the optical wavelength division multiplexing transmission is increased by performing data transmission, that is, passing as it is, the number of electro-optical converters is two or more and the number of optical-electrical converters is two or more. Can be composed of two nodes. In addition, by using the optical wavelength as the reception address of each node and using the time slot as the transmission address of each node, transmission data collision never occurs, and the reception node receives the signal based on the time slot position. There is also an advantage that the media access control process can be simplified since the data transmission node can be confirmed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a data transmission system by optical wavelength multiplexing of an optical LAN system according to claim 1.

FIG. 2 is a diagram showing a data transmission system by optical wavelength multiplexing of the optical LAN system according to claim 2;

FIG. 3 is a diagram showing an embodiment of a node device according to claim 5;

FIG. 4 is a diagram showing an embodiment of a node device according to claim 6;

FIG. 5 is a diagram showing a variable wavelength filter used as the optical wavelength selection switch 4 in FIGS. 3 and 4;

FIG. 6 is a diagram illustrating a conventional node device and a data packet.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Node device of this invention 2 Frame pulse 3 Data packet with different optical wavelengths 4 Optical wavelength selection switch 5 Data interface circuit 6 Frame pulse receiving circuit 7 Optical multiplexer 8 Optical delay line 9 First optical-electrical converter 10 2 optical-electrical converter 11 1st electric-optical converter 12 2nd electric-optical converter group 13 1st optical fiber transmission line 14 2nd optical fiber transmission line 15 Control circuit 16 It has a variable wavelength light source. Second electro-optical converter 17 First optical multiplexer 18 Second optical multiplexer 19 Optical splitter 20 Optical fiber transmission line 21 First input terminal of variable wavelength optical filter using acousto-optic effect 22 Sound Second input terminal of variable wavelength optical filter using optical effect 23 First output terminal of variable wavelength optical filter using acousto-optical effect 24 Variable using acousto-optical effect Second output terminal of long optical filter 25 Optical waveguide of variable wavelength optical filter using acousto-optic effect 26 First TE-TM splitter of variable wavelength optical filter using acousto-optic effect 27 Variable using acousto-optic effect Second TE-TM splitter of wavelength optical filter 28 Electrode of variable wavelength optical filter using acousto-optic effect 29 Acoustic wave region of variable wavelength optical filter using acousto-optic effect 30 Access processing circuit 31 Electro-optical converter 32 Optical-electrical converter 33 Optical filter 34 Optical fiber transmission line 35 Data packet 36 Header section 37 Data section

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04B 10/00 H04J 14/00 H04L 12/40

Claims (6)

(57) [Claims] An optical fiber transmission line for connecting a plurality of nodes and a plurality of nodes in a loop or a bus, and using a plurality of optical wavelengths assigned as addresses of the plurality of nodes, In an optical local area network system that performs data transmission by combining a division multiplexing method and a wavelength division multiplexing method, a plurality of time slots separated by a frame pulse are transmitted, and the time slot is included in one time slot. It is assumed that only one of the plurality of nodes assigned to a slot can transmit data. When a node transmits data, a time slot in which only the node can transmit data is transmitted to a receiving node. If data is transmitted at the corresponding optical wavelength and the node receives the data, all data arriving at the node Only the optical wavelength assigned as the address of the own node out of all the optical wavelengths is drawn into the node, and the other optical wavelengths are passed through as optical signals without being drawn into the node, thereby performing data transmission. A time division multiplexing / optical wavelength division multiplexing composite transmission system for an optical local area network system, characterized in that: And a plurality of nodes and an optical fiber transmission line connecting the plurality of nodes in a loop or a bus, and using a plurality of optical wavelengths assigned as addresses of the plurality of nodes. In an optical local area network system that performs data transmission by combining a division multiplexing method and a wavelength division multiplexing method, a plurality of time slots separated by a frame pulse are transmitted, and each of the plurality of nodes is transmitted to each of the plurality of nodes. A plurality of different time slots capable of transmitting data to all other nodes are allocated, and when a node transmits data, the node can transmit data to a receiving node. In a time slot, data is transmitted using an optical wavelength corresponding to the receiving node, and the node receives the data. In this case, only the optical wavelength assigned as the address of the own node is pulled into the node from among all the wavelengths arriving at the node, and the other optical wavelengths are not pulled into the node and remain as optical signals. A time division multiplexing / optical wavelength division multiplexing composite transmission system for an optical local area network system, characterized in that data transmission is performed by passing through. 3. The transmission of the frame pulse through a first optical fiber transmission line, and the transmission of data by the plurality of optical wavelengths assigned as addresses of the plurality of nodes through a second optical fiber transmission line. 3. A combined time division multiplexing / wavelength division multiplexing transmission system for an optical local area network system according to claim 1, wherein: 4. The transmission of the frame pulse and the data transmission using the plurality of optical wavelengths assigned as addresses of the plurality of nodes are performed through one optical fiber transmission line.
3. The optical local area network according to claim 1, wherein an optical wavelength for transmitting the frame pulse and the plurality of optical wavelengths assigned as addresses of the plurality of nodes are different optical wavelengths. System time division multiplexing / optical wavelength division multiplexing composite transmission system. 5. A frame pulse receiving circuit for receiving a frame pulse and generating data transmission timing in a node, an optical input terminal connected to an input terminal of the first optical fiber transmission line, and an electric output terminal connected to the input terminal. A first optical-to-electrical converter connected to the input of the frame pulse receiving circuit, and an electrical input terminal connected to the output of the frame pulse receiving circuit and an optical output terminal connected to the output end of the first optical fiber transmission line. The data transmitted from the connected first electro-optical converter and the data transmitted from the external device are output to a plurality of second electro-optical converter groups according to the timing signal from the frame pulse receiving circuit. A data interface circuit for sending data from the optical-to-electrical converter to the external device, and outputting to the second output terminal only a specific optical wavelength of the plurality of optical wavelengths input from the input terminal. An optical wavelength selection switch having a function of outputting other optical wavelengths to a first output terminal and having a first output terminal connected to an output end of a second optical fiber transmission line; The second optical-to-electrical converter, which converts an optical signal from the second output terminal into an electrical signal and outputs the electrical signal to the data interface circuit, and converts a plurality of electrical signal data from the data interface circuit into different wavelengths. A plurality of second electro-optical converter groups for converting and outputting a plurality of optical signals; a plurality of input / output converters having a plurality of input terminals and one output terminal, the output terminals being connected to the input terminals of the wavelength selective switch; An optical multiplexer having one of the input terminals connected to the output of the optical delay line and the other input terminal connected to the optical output terminal of the second electro-optical converter group; Input end of fiber transmission line It connected the optical delay line and a node apparatus for an optical local area network system for implementing the method according to claim 1 or claim 3 composed of. 6. A frame pulse receiving circuit for receiving a frame pulse and generating data transmission timing within a node, and a first optical wavelength for transmitting a frame pulse among a plurality of input optical wavelengths. An optical splitter having a function of outputting to an output terminal and outputting other light wavelengths to a second output terminal, an input terminal connected to an input end of an optical fiber transmission line, and an optical input terminal connected to the optical splitter A first optical-to-electrical converter having an electrical output terminal connected to the first output terminal and an electrical output terminal connected to the input of the frame pulse receiving circuit, and an optical output having an electrical input terminal connected to the output of the frame pulse receiving circuit. A first electro-optical converter having a terminal connected to a first input terminal of the first optical multiplexer; and a variable data transmitted from an external device in accordance with a timing signal from the frame pulse receiving circuit. Light wave A data interface circuit for outputting to a second electro-optical converter having a light source and transmitting data from the second electro-optical converter to the external device; and a plurality of optical wavelengths input from an input terminal. It has a function of outputting only a specific light wavelength to the second output terminal and outputting other light wavelengths to the first output terminal, and the first output terminal is a second input terminal of the first optical multiplexer. An optical wavelength selective switch connected to the optical wavelength selective switch, the second optical-electrical converter for converting an optical signal from a second output terminal of the optical wavelength selective switch into an electric signal, and outputting the electric signal to the data interface circuit; A second optical multiplexer including a first optical multiplexer having a terminal connected to an output end of the optical fiber transmission line, and the variable wavelength light source that converts electrical signal data from the data interface circuit into an optical signal and outputs the optical signal; Electricity-light And a first input terminal connected to the optical output terminal of the second electro-optical converter, a second input terminal connected to the output of the optical delay line, and an output terminal connected to the input terminal of the wavelength selective switch. A second optical multiplexer connected to the second optical multiplexer, the optical delay line having an input connected to a second output terminal of the optical splitter, and the second electrical multiplexer based on receiving node address information from the data interface circuit. A node device of an optical local area network system for realizing the method according to claim 2 or 3, comprising a control circuit for controlling an output light wavelength of the optical converter.