JPH0263344A - Optical star network type communication system - Google Patents

Abstract

PURPOSE:To use the transmission line with high efficiency by providing a buffer capable of storing communication information tentatively when communication information is in congestion with communication controllers. CONSTITUTION:A switch control circuit 21A-5 of a communication controller 2 switches a matrix switch section 22 at first so that the communication information from an incoming line starting the communication at first can be outputted from a required outgoing line. However, while the initial communication information is being outputted through the outgoing line, when other communication information is received through other incoming line, the circuit 21A-5 switches the matrix switch section 22 so that the communication information received through the other incoming line is supplied to a buffer 24. On the other hand, when the outgoing line is idle, the matrix switch section 22 is changed over so that the communication information stored in the buffer 24 is outputted through the outgoing line. Thus, the transmission line is used with high operating efficiency.

Description

[Detailed Description of the Invention] [Summary] The present invention has a plurality of terminals and a communication control device connected to each terminal via a transmission path, and uses carrier sense multiple access as an access method for the transmission path. Regarding the optical star network type communication system that uses the optical star network method, the aim is to make it possible to resolve conflicts within the communication control device as much as possible in the case of transmission line access conflicts, thereby achieving high utilization efficiency of the transmission line. The communication control device includes an optical/electrical converter that converts optical output from each terminal into an electrical signal, and a matrix switch unit that outputs the electrical signal from each optical/electrical converter to a required outgoing line.
An electrical/optical converter connected to a required output line of the matrix switch section, a buffer connected to another output line of the matrix switch section that temporarily stores communication information from the optical/electrical converter, and each optical /A switch control circuit that performs switching control of the matrix switch section based on the electric signal from the electric converter.

[Industrial Field of Application] The present invention relates to an optical star network communication system.

In recent years, with the increase in the amount of communication handled by devices, attempts have been made to apply optical transmission technology.

For example, multiple terminals are connected to a communication control device (hub or node) via a transmission path (uplink, downlink) to form an optical bus, and a carrier is used as the access method for the transmission path. Multiple access method using sense [CS MA/CD (Carrier 5en
ce Multiple Access/Co11is
There is an optical star network type communication system that uses the ionDetect method].

Here, in the C8MA/CD method, when a certain terminal tries to start communication, it first checks the status of the transmission path, confirms that the transmission path is not in use, and then waits for a while before starting communication. While sending information onto the transmission path, it is also necessary to detect whether or not there is a collision with other communication information on the transmission path, and if a collision occurs, a method is developed that can retransmit the communication information say.

[Prior Art] By the way, FIG. 4 is a block diagram of a conventional optical star network communication system.
1 is a terminal (communication module), 2 is a communication control bag W (hereinafter sometimes referred to as a hub), and between each terminal 1 and the hub 2 are an uplink 3 and a downlink 4 as transmission paths.
connected with.

Then, hub 2 has uplink 3 and downlink 4.
A switch section 2A configured of a star coupler or the like is provided to connect the two. This switch section is functionally the same as a wired or.

With this configuration, when a certain terminal 1 tries to start communication, it first connects the uplink 3 and downlink 4.
After confirming that the transmission path is not in use, the communication information is sent onto the uplink 3 after a while. As a result, this communication information is broadcast (circuited) to the remaining terminals 1 via the hub 2 that constitutes the optical bus.
be done.

Then, each terminal 1 detects the header information included in the communication information, and if the communication information is directed to itself, the terminal 1 takes in the communication information, but if not, it does not take in the communication information.

On the other hand, even after communication information is sent from a certain terminal 1, it is detected whether or not there is a collision between this communication information and communication information from another terminal 1 on the transmission path. In this case, the communication information is retransmitted.

In this optical star network type communication system, the switch section of the hub is classified into two types depending on whether it is passive or active.

Here, when a hub's switch section is passive, it means that it outputs the input optical signal as it is after undergoing the required processing (wired OR), and when a hub's switch section is active, it means that it outputs the input optical signal as it is. , converts an input optical signal into an electrical signal, performs the necessary processing (wired or) on this electrical signal, converts it back to an optical signal, and then outputs it.

This is an optical star network type communication system that allows transmission line access conflicts to be resolved as much as possible within the communication control device (hub), allowing the transmission line to be used with high efficiency. The purpose is to provide a system.

[Problems to be Solved by the Invention] However, in such a conventional CDMA/CD optical star network communication system, if data collides when two or more terminals access at the same time,
Since data is retransmitted, the throughput of the transmission path depends on the collision resolution time at that time, and n! j depends on the propagation delay time.

Therefore, in a method in which a hub performs wired-OR for each uplink, and each terminal accesses the transmission path using carrier sense, even if the speed of the transmission path is increased, the corresponding throughput cannot be obtained. There is a problem in that the road cannot be used with high efficiency.

The present invention attempts to solve these problems [Means for Solving the Problem] FIG. 1 is a block diagram of the principle of the present invention.

As shown in FIG. 1, the device according to the present invention also has a plurality of terminals 1 and a communication control device 2 connected to each terminal 1 via transmission paths 3 and 4, This relates to an optical star network type communication system that uses a carrier sense multiple access method as an access method, and in this invention, six communication control devices 2 are connected to each terminal 1.
A plurality of optical/electrical converters 2 are provided corresponding to each terminal 1 to receive optical output from the terminal 1 and convert the optical output into an electrical signal.
1, a matrix switch unit 22 that outputs the electrical signal from each optical/electrical converter 21 to a required outgoing line, and an electrical/optical converter 'a23 connected to the required outgoing line of this matrix switch unit 22, A buffer 24 that is connected to another outgoing line of the matrix switch section 22 and temporarily stores communication information from the optical/electrical converter 21, and each optical/electrical converter 2.
Matrix switch section 22 based on the electrical signal from 1
The device includes a switch control circuit 25 that performs switching control, and an optical distributor 26 that distributes the optical signal from the electrical/optical converter 23 to each terminal 1.

[Function] With this configuration, when a certain terminal 1 attempts to start communication, it first checks the status of the transmission paths 3 and 4, confirms that the transmission paths are not in use, and then After a while, the communication information is sent onto the transmission line 3. Thereby, this communication information is broadcasted to the remaining terminals 1 via the communication control device 2. So, on each terminal 1,
The header information included in the communication information is detected, and if the communication information is directed to the user, the communication information is captured, but if not, the communication information is not captured.

By the way, the switch control circuit 21A- of the communication control device 2
5 switches the matrix switch section 22 as follows.

First, the matrix switch unit 22 is switched so that the communication information from the incoming line that first started communication is output through the required outgoing line, but while the first communication information is being output through this outgoing line, another When communication information is input through an incoming line, the matrix switch section 22 is switched so that the communication information input through another incoming line is supplied to the buffer 24, while when the outgoing line becomes vacant, the communication information is stored in the buffer 24. The matrix switch section 22
Switch.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

As shown in FIG. 2, this embodiment also includes a plurality of terminals (communication modules or communication interfaces, etc.) 1, and an uplink 3 as a transmission path for each terminal 1.
．． This is an optical star network type communication system that has a hub (communication control device) 2 connected via a downlink 4 and uses the above-mentioned CDMA/CD method as a transmission path access method. , in this embodiment, the hub 2 includes optical/electrical converters 21 . Matrix switch section (packet switch) 22. Electrical/optical converter 23
．． Buffer 24. Switch control circuit 25 with carrier detection circuit 29. Optical demultiplexer 26. It is configured with amplifiers 27 and 28.

First, the optical/electrical converter 21 is provided in multiple stages corresponding to each terminal 1, and each electrical output is amplified by a corresponding amplifier 27.

The matrix switch section 22 includes each optical/electrical converter 21
The matrix switch section 22 outputs electrical signals from the matrix switch section 22 to required outgoing lines, and a memory or a semiconductor switch is used as the matrix switch section 22, for example.

The electrical/optical converter 23 is connected to a required output line of the matrix switch section 22 via an amplifier 28, converts the electrical output from the matrix switch section 22 into an optical signal, and uses a laser diode or the like. .

The buffer 24 is connected to another outgoing line of the matrix switch section 22 and temporarily stores communication information from the optical/electrical converter 21.

The switch control circuit 25 uses a carrier detection circuit 29 to detect communication information (
It detects the presence or absence of carrier) and controls the switching of the matrix switch section 22 based on the detection result.
An example of switching control of the matrix switch section 22 by the switch control circuit 25 is as follows.

That is, the matrix switch section 22 is switched so that the communication information from the incoming line that first starts communication is outputted through the required outgoing line connected to the electrical/optical converter 23, and the first communication information is outputted through this outgoing line. If communication information is input through another input line while it is being output, the communication information input through this other input line is transferred to the buffer 24.
On the other hand, when the outgoing line connected to the electrical/optical converter 23 becomes vacant, the communication information stored in the buffer 24 is outputted through this outgoing line. , the matrix switch section 22 is switched.

As a result, communication information input later can be retrieved from a required outgoing line without being discarded, thereby increasing the efficiency of using the transmission path.

The optical demultiplexer 26 demultiplexes the optical input from the electrical/optical converter 23 into a plurality of optical outputs.For example, as shown in FIG. A star coupler is used which inputs an optical fiber input into a mixing rod 26A-2 covered with a cladding layer 26A-1 and outputs it to a plurality of optical fibers.

With the above-described configuration, when a certain terminal 1 attempts to start communication, first the uplink 3. After checking the status of the downlink 4 and confirming that the transmission path is not in use, the communication information is sent onto the uplink 3 after a while. As a result, communication information is transmitted to the remaining terminal 1 via hub 2.
will be broadcast (circulated). And each terminal 1
Then, the header information included in the communication information is detected, and if the communication information is directed to the user's location, the communication information is captured, but if not, the communication information is not captured.

By the way, in the hub 2, the switch control circuit 25 is
The matrix switch section 22 is switched in the following manner.

First, the matrix switch unit 22 is switched so that the communication information from the incoming line that first started communication is output through the required outgoing line, but while the first communication information is being output through this outgoing line, another When communication information is input through an incoming line, the matrix switch section 22 is switched so that the communication information input through another incoming line is supplied to the buffer 24, while when the outgoing line becomes vacant, it is stored in the buffer 24. The matrix switch section 22
Switch. This allows the transmission path to be used with high efficiency.

Furthermore, even after communication information is sent from a certain terminal 1, it is detected whether or not there is a collision between this communication information and communication information from another terminal 1 on the transmission path, and if a collision occurs, In this case, the communication information is retransmitted.

Further, the number of buffers 24 is not limited to one, and as shown by the chain line in FIG. Depending on the situation, three or more buffers may be provided on the outgoing lines of the matrix switch section 22. In this way, even if three or more pieces of communication information conflict, there is no need for retransmission, and the throughput of the transmission path can be further increased.

[Effects of the Invention] As detailed above, according to the optical star network type communication system of the present invention, the communication control device has a buffer that can temporarily store communication information when there is a conflict of communication information. Since this is provided, there is an advantage that the transmission line can be used with high efficiency.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a block diagram showing an embodiment of the invention, Fig. 3 is a diagram showing an optical demultiplexer, and Fig. 4 is a block diagram showing a conventional example. . In the figure, 1 is a terminal, 2 is a communication control device (hub), 3 is an uplink, 4 is a downlink, 21 is an optical/electrical converter, 22 is a matrix switch section, 23 is an electrical/optical converter, and 24 is an electrical/optical converter. buffer. 25 is a switch control circuit, 26 is an optical demultiplexer, 26A-1 is a cladding layer, 26A-2 is a mixing rod, 27.28 is an amplifier, and 29 is a carrier detection circuit. Kuimakari Road 4 Hosu District Map 3

Claims (1)

[Claims] A plurality of terminals (1) and a transmission path (3,
4) has a communication control device (2) connected via the
Further, in an optical star network type communication system that uses a carrier sense multiple access method as an access method for the transmission path, the communication control device (2) receives optical output from each terminal (1) and outputs the optical output. a plurality of optical/electrical converters (21) provided corresponding to each terminal (1) to convert the electrical signals into electrical signals; A matrix switch section (22) that outputs to a line, an electrical/optical converter (23) connected to a required output line of the matrix switch section (22), and another output line of the matrix switch section (22). a buffer (24) that is connected to the optical/electrical converter (21) and temporarily stores communication information from the optical/electrical converter (21); ), and the switch control circuit (25) controls the switching so that the communication information from the incoming line that first starts communication is output through the required outgoing line. , while switching the matrix switch section (22), if communication information is input through another incoming line while the first communication information is being output through the outgoing line, the communication information input through this other incoming line is The matrix switch section (22) is switched so that the output line is supplied to the buffer (24), and when the outgoing line becomes vacant, the communication information stored in the buffer (24) is supplied to the outgoing line through the outgoing line. As output,
An optical star network communication system characterized by switching the matrix switch section (22).