JPS6211536B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Technical Field of the Invention The present invention provides high-speed and highly reliable communication between multiple terminals by sharing and using one optical fiber cable between each terminal. Concerning optical bus network systems that enable

(2) Background of technology Recently, as the number of terminals and the amount of transmitted data increases, communication systems such as data communication systems are required to have high speed and high reliability. With the development of technology, there is a need for devices that can communicate between arbitrary terminals.

(3) Prior Art and Problems Therefore, for example, a bus network system as shown in FIG. 1 has been put into practical use. The system in the figure has multiple nodes 2 on a coaxial cable 1.
It is configured by electrically connecting multiple terminals 3-1, 3-2, 3-n through -1, 2-2, 2-n. . In such a communication system, data can be sent and received between arbitrary terminals via a coaxial cable 1, etc., or data can be transmitted from an arbitrary terminal to multiple other terminals simultaneously. Information communication is possible.

However, in the conventional type shown in FIG. 1, since the transmission band is limited by the coaxial cable, it is difficult to perform wideband and high-speed signal transmission, and each node 2-1, 2-2, . . . ......
..., 2-n and the coaxial cable 1, etc., due to noise due to impedance mismatch, etc., and the transmission quality is disadvantageously degraded.

It is also possible to replace the coaxial cable in the system shown in Figure 1 with an optical fiber cable, but the structure of the connecting part to connect the optical fiber cable and the node to enable bidirectional transmission is quite complicated. This has the disadvantages of lower reliability and higher price.

(4) Purpose of the Invention The purpose of the present invention is to provide an optical transmission line using an optical fiber cable bent in an S-shape or a U-shape in an optical bus network system, in view of the problems of the conventional type described above. The object of the present invention is to enable high-speed signal transmission with a simple configuration and to improve the reliability of the system.

(5) Structure of the Invention According to the present invention, this purpose is to improve the optical bus network system in which multiple terminals share and use one optical fiber cable to communicate between each terminal. The end of the fiber cable is terminated without reflection, and the optical fiber cable is bent into a U-shape or an S-shape to form an uplink (or transmission line) and a downlink (or reception line), and at each branch/insertion point. The terminal is connected via uplink and downlink optical passive circuits,
This is achieved by an optical regenerator that regenerates the optical signal between the terminals at a predetermined threshold.

(6) Embodiments of the invention Examples of the invention will be described below with reference to the drawings.
FIG. 2 shows an optical bus network system according to an embodiment using the U-shaped optical fiber cable of the present invention. In the same figure, 5 is a U-shaped optical fiber cable, 6 and 7 are uplink and downlink respectively constituted by the optical fiber cable 5, and 8 is a limiter 8-- inserted into these uplink and downlink lines. This is an optical regenerative repeater with 1. 9-1,9
-2, 9-3, ........., 9-m are optical couplers for optical signal insertion inserted into the uplink line 6 of each drop/add point, and 10-1, 10-2, 10-3 ,…
......, 10-m are optical couplers 9-1 and 9-, respectively.
This is an optical coupler for optical signal branching inserted into the downlink line 7 at the same insertion/branching point as 2, 9-3, 9-m. 11-1, 11-2, 11-3,...
......, 11-m is each optical coupler at each branch/addition point and optical fiber cable for transmission 12-1, 12-
2, 12-3, ......12-m and receiving optical fiber cable 13-1, 13-2, 13-
It is a node connected via 3, . . . , 13-m, and has optical/electrical conversion and data transmission/reception control functions. 14-1, 14-2, 14
-3, ......, 14-m are the respective nodes 11
-1, 11-2, ……………, 11-m. In the figure, one data terminal is connected to one node, but one node has multiple terminals connected to it. It is also possible to connect In addition, both ends 5 of the above-mentioned optical fiber cable 5
A and 5b are non-reflection terminated to prevent reflection of optical signals by, for example, cutting diagonally and blocking external light. In addition, in the above, each optical coupler as an optical passive circuit inputs the optical signal from the transmission optical fiber cable to the uplink optical fiber cable or downlink by means of a half mirror inserted diagonally into the optical transmission line. The optical signal from the line's optical fiber cable is branched to a receiving optical fiber cable and output.

In the configuration shown in FIG. 2, communication between each terminal is performed as follows. For example, when transmitting data from terminal 14-1 to terminal 14-3, terminal 14-1
-1 is converted into an optical signal at the node 11-1, and the optical signal is sent to the transmission optical fiber cable 12-1, the optical coupler 9-1, and the uplink line 6.
The optical signal is input to the optical regenerator 8 via the optical cable 6, the optical coupler 9-1, etc., and is attenuated by the optical cable 6, the optical coupler 9-1, etc., and then equalized. The equalized optical signal is shaped by a limiter 8-1 to a constant level using a predetermined threshold value, and is regenerated into an optical signal for transmission.
C, downlink line 7, optical coupler 10-3, receiving optical fiber cable 13-3, and node 11-3
is transmitted to terminal 14-3 via.

Conversely, when transmitting data from the terminal 14-3 to the terminal 14-1, the data signal from the terminal 14-3 is sent to the node 11-3, the transmission optical fiber cable 12-3, the optical coupler 9-3, Optical regenerative repeater 8 via uplink 6, bending section 5C, downlink 7
In the same way as above, the limiter 8-1 shapes the output to a predetermined threshold value and regenerates the downstream line 7, the optical coupler 10-1, the receiving optical fiber cable 13-1,
It is transmitted to terminal 14-1 via node 11-1.

In any of the above cases, the transmitted data is branched to each node, but the transmitted data contains the destination address of the transmitted data, that is, the destination address, and the transmitted data is only transmitted at the node corresponding to this destination address. By taking in the information as information, the data can be transmitted to the terminal of the desired node.

3a and 3b show the configuration of the optical regenerative repeater 8 used in the system of FIG. 2, the received optical signal, and the waveform at each point of the repeater 8.

In Figure a, the optical signal of the uplink 6 is input to the optical regenerative repeater 8, and is converted into a digital signal by the optical-to-electric conversion circuit 8-2 of the repeater 8, and the signal is equalized and amplified. The waveform (1) is limited by the limiter 8-1 to form the waveform (2).
It is further shaped into an optical signal (3) by an electric/optical conversion circuit 8-4, and then sent to an uplink line 6 and an optical coupler 9-3.
It is transmitted to the downlink 7 (not shown) via .........

In waveform (1) of the same b, (1)-9-1 shows the transmitted signal of the optical coupler 9-1, and (1)-9-2 shows the transmitted signal of the optical coupler 9-2, and the level of both. The difference Vd is due to a transmission loss caused by a difference in the transmission path of the uplink 6.

The waveform (1) is limited by a predetermined threshold value (1)-1 in a limiter 8-1 and shaped into a waveform (2). When the waveform is shaped in this way, the S/N is improved.

The above has described a U-shaped optical fiber cable, but an optical bus network system can be constructed using the same method for an S-shaped fiber cable.If the optical repeater has limiter characteristics, the level of the received signal will differ due to the difference in the transmission path. can also be shaped into a waveform as shown in Figure 3 (2).

FIG. 4 shows another embodiment of the present invention, in which the optical regenerator according to the present invention is applied to an optical bus network system using S-shaped optical fiber cables, and the optical regenerator according to the present invention is applied to an optical bus network system using S-shaped optical fiber cables. This is an improved U-shape for data transmission so that there are no differences in priority depending on the location of the node. In the figure, 5 is an optical fiber cable that is bent into a substantially S-shape to form one optical transmission path, and 6'
and 7' are a transmission line and a reception line constituted by the optical fiber cable 5, respectively, and 8 is an optical repeater inserted into these transmission and reception lines. 9-1, 9-2, 9-3, ……………
9-m is an optical coupler for optical signal insertion inserted into the transmission line 6' of each branch/add point, and 10-1, 1
0-2, 10-3, ........., 10-m are optical couplers 9-1, 9-2, 9-3, ......
..., 9-m is an optical coupler for optical signal branching inserted into the receiving line 7' at the same branching/adding point. 11-
1, 11-2, 11-3, ……………, 11-m
are each optical coupler at each branch/insertion point and transmission optical fiber cables 12-1, 12-2, 12-3,...
......, 12-m and receiving optical fiber cables 13-1, 13-2, 13-3, ......., 1
3-m, and has photoelectric conversion and data transmission/reception control functions. 1
4-1, 14-2, 14-3, ……………, 14
-m are nodes 11-1, 11-2, 11 respectively
It is a data terminal connected to -3,......,11-m, and in the figure, one data terminal is connected to one node, but it is also possible to connect multiple terminals to one node. is also possible. In addition,
Both ends 5a and 5b of the above-mentioned optical fiber cable 5
are non-reflection terminated to prevent reflection of optical signals, for example by cutting diagonally and blocking external light. In addition, in the above, each optical coupler as a passive optical circuit inputs an optical signal from the transmission optical fiber cable to the optical fiber cable of the transmission line 6' by means of a half mirror inserted diagonally into the optical transmission line. Alternatively, the optical signal from the optical fiber cable of the receiving line 7' is branched to a receiving optical fiber cable and output.

In the configuration shown in FIG. 4, communication between each terminal is performed as follows. For example, when transmitting data from terminal 14-1 to terminal 14-3, terminal 14-1
The data signal from -1 is converted into an optical signal at node 11-1, and the transmission optical fiber cable 1
2-1, optical coupler 9-1, transmission line 6', bending parts 5c, 5d, reception line 7', optical coupler 10-
3, transmitted to the terminal 14-3 via the receiving optical fiber cable 13-3 and the node 11-3. Conversely, when transmitting data from the terminal 14-3 to the terminal 14-1, the data signal from the terminal 14-3 is sent to the node 11-3, the transmission optical fiber cable 12-3, the optical coupler 9-3, Transmission line 6', optical repeater 8, bending parts 5c, 5d, reception line 7', optical repeater 8, reception line 7', optical coupler 1
0-1, the receiving optical fiber cable 13-1, and the node 11-1, and are transmitted to the terminal 14-1. In any of the above cases, the transmitted data includes the destination address of the transmitted data, that is, the destination address, and by taking in the transmitted data as information only in the node corresponding to this destination address, the desired node This makes it possible to send data to other terminals.

FIG. 5 shows the configuration of nodes used in the system of FIG. 2. The nodes in FIG. 3 include an electro-optical conversion circuit 17 (corresponding to E10 8-4), an optical-electrical conversion circuit 18, a packet transmitting circuit 19, a packet receiving circuit 20, a collision detection circuit 21, a clock generating circuit 22, and a transmitting buffer memory. 23, transmission control circuit 24, reception buffer memory 25, reception control circuit 26, data link controller 27 composed of a microprocessor, etc., and line interfaces 28-1, 28-2, 28-3, 28
-4 etc. In addition, line interfaces 28-1, 28-2, 28-3, 28-4
are terminals 29-1, 29-2, 29-3, respectively.
29-4, and the electro-optical conversion circuit 17 and the photo-electric conversion circuit 18 are connected to the transmitting optical fiber cable 12 and the receiving optical fiber cable 1, respectively.
3 is combined.

In the node of FIG. 5, for example, the terminal 29-1
When transmitting data from the terminal 29-1 to a terminal connected to another node (not shown), input data from the terminal 29-1 is input to the data link controller 27 via the line interface 28-1, and the destination address, originating The original address and various types of control information are added to form a packet, which is stored in the transmission buffer memory 23. Next, the transmission control circuit 2
4 determines the presence or absence of a received signal by monitoring the output of the opto-electrical conversion circuit 18, and if there is no received signal, it is determined that the optical transmission line is in an empty state, and the packet stored in the transmission buffer memory 23 is transmitted. It is transferred to the transmitting circuit 19. A transmission electrical signal corresponding to the packet is created in the packet transmission circuit 19, converted into an optical signal in the electro-optical conversion circuit 17, and sent to the transmission optical fiber cable 12. The optical signal sent out to the transmission optical fiber cable 12 in this way passes through the transmission line bending section and the reception line as described above, and is received again by the reception optical fiber cable 13 of the same node, and is sent to the opto-electric conversion circuit. At step 18, the signal is converted into an electrical signal and input to the collision detection circuit 21. The collision detection circuit 21 compares the input electrical signal with the previously transmitted electrical signal to determine whether the data was transmitted correctly and whether there was a collision with the transmitted signal from another node. and confirm that the transmission was successful. If it is detected through this determination that normal transmission is not being performed, data is retransmitted, for example.

When the node in Figure 5 receives data sent from a terminal connected to another node,
An optical signal corresponding to the data is input to the opto-electrical conversion circuit 18 via the receiving optical fiber cable 13, and after being converted into an electrical signal, the packet receiving circuit 2
0 is stored in the reception buffer memory 25. At this time, the reception control circuit 26 determines whether the transmission destination address in the received data, that is, the destination address, matches the address of its own node, and if they match, transfers the received data to the data link controller 27, If they do not match, the received data is deleted. Data link controller 2
7 transfers the input received data to the terminal corresponding to the terminal number information included in the destination address in the received data.

FIG. 6 shows in detail an example of an actual communication procedure in the optical bus network system shown in FIGS. 2 and 5. In the figure, it is assumed that data is transmitted from one terminal DTEA to another terminal DTEB, and MPUA and
MPUB connects each of these data terminals DTEA and
Figure 3 shows a data link controller in a node connected to DTEB. First, basic processing is performed at the terminal DTEA to create a packet header including a destination address and a source address in response to a transmission start command. Next, the message length, address data, packet type information indicating the type of data, message number, etc. are added to the given transmission data, and the data is transferred to the data link controller MPUA (hereinafter referred to as MSUA). When the MPUA receives this information, it returns an acceptance signal ACK1 to the terminal DTEA, edits (assembles) this information, adds error check bits, etc., creates a transmission packet, and sends it via the optical transmission path mentioned above. Data link controller MPUB of other nodes (hereinafter simply referred to as MPUB)
Send to. In MPUB, when the transmission packet is correctly received, the reception signal MCK2 is sent to MPUA.
The MPUA then deletes the transmitted packet, assuming that the transmitted packet has been correctly transmitted. In this case, if the MPUA cannot transmit the transmission packet correctly due to a collision of optical signals on the optical transmission path, etc., it will transmit the packet up to 16 times, and if it is still unable to transmit the packet correctly even after 16 transmission processes, it will Sends a message to the terminal DTEA. When the transmission packet is correctly transmitted to MPUB, the transmission packet is disassembled in MPUB, and only the necessary data is transferred to the terminal DTEB. When the terminal DTEB correctly receives the data, it transmits an acceptance signal ACK1' to MPUB, which causes MPUB to erase the received packet. Next, the terminal DTEB sends return data such as a confirmation message to the terminal according to the content of the received data.
If it is necessary to send the data back to DTEA, the message length, address data, packet type data, etc. are added to the returned data and the data is transferred to MPUB.
MPUB creates a sending packet in the same way as above.
The transmitted packet is transmitted to the MPUA, and the transmitted packet is disassembled at the MPUA and transferred to the terminal DTEA. In this way, data transmission for one cycle is completed, and the necessary data transmission is performed in the same procedure.
By inputting the transmission end command, processing such as clearing each buffer memory is performed, and all transmission procedures from the terminal DTEA are completed.

(7) Effects of the Invention Therefore, according to the present invention, each optical signal sent out from each node on a bus network is received at a different level, equalized and amplified in an optical regenerator, and further amplified in a limiter. Since the optical signal is shaped to a constant level and sent out, the optical signal on the transmission line has the advantage of improved S/N ratio.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a conventional bus network system, FIG. 2 is a schematic block circuit diagram showing an optical bus network system according to an embodiment of the present invention, and FIGS. 3a and 3b are 4 shows another embodiment of the present invention, and FIG. 5 is a block circuit diagram showing the configuration of nodes in the system of FIG. 2.
FIG. 6 is an explanatory diagram showing the transmission procedure in the system of FIG. 2. 1: Coaxial cable, 2-1, 2-2,……
..., 2-n: node, 3-1, 3-2, ......
..., 3-n: terminal, 5: optical fiber cable, 5
a, 5b: end portion, 5c, 5d: bent portion, 6:
Uplink, 6': Transmission line, 7: Downlink, 7':
Reception line, 8: Optical repeater, 9-1, 9-2, 9-
3,......,9-m: Optical coupler, 10-1,
10-2, 10-3, ........., 10-m: Optical coupler, 11-1, 11-2, 11-3, ......
..., 11-m: node, 12, 12-1, 12
-2, 12-3, ……………, 12-m: Optical fiber cable for transmission, 13, 13-1, 13-
2, 13-3, ……………, 13-m: Optical fiber cable for reception, 14-1, 14-2, 14-
3,......, 14-m: Data terminal, 17:
Electrical/optical conversion circuit, 18: Optical/electrical conversion circuit, 1
9: Packet transmission circuit, 20: Packet reception circuit, 21: Collision detection circuit, 22: Clock generation circuit, 23: Transmission buffer memory, 24: Transmission control circuit, 25: Reception buffer memory, 26: Reception control circuit, 27: Data link controller, 28
-1, 28-2, 28-3, 28-4: Line interface, 29-1, 29-2, 29-3, 2
9-4: Terminal.

Claims (1)

[Claims] 1. In an optical bus network system in which multiple terminals share and use one optical fiber cable to communicate between each terminal, the end of the optical fiber cable is terminated with non-reflective termination and the fiber cable is is bent into a U-shape or an S-shape to configure an uplink (or transmission line) and a downlink line (or reception line), and the terminal is connected to the terminal via the uplink and downlink optical passive circuits at each branch and insertion point. An optical bus network system characterized by having an optical regenerator connected to the terminals and regenerating an optical signal between the terminals at a predetermined threshold.