JPH01208921A - Optical fiber transmission system - Google Patents

Abstract

PURPOSE:To allow each equipment to receive a transmission signal of all equipment by using a light of a different wavelength for the transmission from a master node equipment to a sub node equipment, the transmission from the sub node equipment to the master node equipment and the transmission between the sub node equipments, mixing the light once in a star coupler and distributing the result to each equipment. CONSTITUTION:A signal from the master node equipment 1 and the signal from the sub node equipment 2 are both inputted to a port of the same side of the star coupling 3. Then an output from the other port is returned to both the master node equipment 1 and the sub node equipment 2. The star coupler 3 is installed near the sub node equipment 2. Furthermore, lights of different wavelengths lambda1, lambda2 are used for the transmission for the master node equipment 1 and the sub node equipment 2. Thus, even if the both make transmission at the same time, no signal collision takes place. The star coupler 3 mixes once the transmission signals and then distributes the result to each equipment. Then each equipment receives the transmission of all the equipment including itself.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for connecting a plurality of signal transmitting/receiving devices with optical fibers to enable mutual signal transmission.

[Conventional technology]

FIGS. 3(a) and 3(b) show the configuration of a conventional transmission system using a star coupler.

In these conventional systems, a signal transmitted from the main node device 1 is energy-distributed by the star coupler 3 and reaches each sub-node device 2.

Further, the signals transmitted from each sub-node device 2 are combined by a star coupler 3 and reach the main node device l.

When using light of the same wavelength λl for uplink and downlink signals, two sets of optical fibers 4 and star couplers 3 are used as shown in FIG. 4(a). Moreover, different wavelengths λ1. When wavelength multiplexing technology using λ2 is used, 1
It is also possible to configure it by a set of optical fibers 4 and star coupler 3. This method has the following advantages.

(2) Since the optical fiber 4 is shared up to the vicinity of the sub-node device 2, it is economical.

■Distribution of signals from the main node device 1 to the sub node device 2,
Furthermore, although signals are collected from the sub-node device 2 to the main node device l via the star coupler 3, there are the following advantages.

1. Star coupler 3 is a passive component, so it is highly reliable.

b. It is easy to add sub-node devices 2.

C8 main node device! Since the signal from the node is transmitted to the fully open node device, broadcast communication is easy.

However, this method has the following drawbacks.

(2) When communicating between the sub node devices 2, it is necessary to pass the signal through the main node device I once.

■Since neither the main node device 1 nor the sub-node device 2 can receive the signal sent by itself, confirmation of signal arrival must be performed separately.

(2) Since the main node device 1 and the sub node device 2 are not equal, even if the main node device I is connected to the position of the sub node device 2, it cannot function as the main node device 1.

FIG. 4 shows a conventional local area network using a star coupler 3.

In the case of this local area network, a signal transmitted by each node is energy distributed by the star coupler 3 and reaches all nodes including the source node. Each node transmits signals using light of the same wavelength.

This method has the following advantages.

■Transmission between each node can be performed directly without going through other nodes.

■Broadcast communication can be performed from one node to all other nodes.

- Since all the signals transmitted by each node return to the source, it is easy to detect breaks in the optical fiber 4.

■Logically, each node is connected equally to the bus, so if there is a distinction between main nodes and sub nodes, when a failure occurs in the main node device, etc.
Sub node device 2 without changing the connection of optical fiber 4
Let it act as the main node.

However, this method has the following drawbacks when there is a distinction between the main node and the sub nodes.

■Since both the main node and the sub-node use light of the same wavelength, a control function is required to reduce signal collisions and their effects (for example, CSMA1CSMA/CD).

(2) If there is a lot of traffic from the main node to the secondary node, the transmission capacity (2) from the secondary node to the main node is limited.

[Problem to be solved by the invention]

An object of the present invention is to provide a new optical fiber transmission system that takes advantage of the mutual drawbacks of the conventional transmission systems shown in FIGS. 3(a) and 3(b) and the conventional transmission system shown in FIG. shall be.

[Means to solve the problem]

The optical fiber transmission system of the present invention includes a main node device, a sub node device, a star coupler,
A transmission method consisting of optical fibers connecting them, and transmitting and receiving signals between the main node device and the sub node devices and between the sub node devices. Between the main node device and the star coupler, and with each sub node device. Each star coupler is connected using multiple optical fibers, and the transmission output of both the main node device and the sub node device is connected to one port of the star coupler, and the output from the other board of the star coupler is The signal is returned to both the main node device and the sub node device, and the signals from the main node device and the sub node device to the star coupler, and the signals from the star coupler to the main node device and the sub node device are transmitted using separate optical fibers. , is characterized in that light of different wavelengths is used for transmission from the main node device to the sub node device and for transmission between the sub node device to the main node device and the sub node devices.

[Effect]

The optical fiber transmission system of the present invention inputs both the signal from the main node device and the signal from the sub-node device, which uses light of a different wavelength from that of the main node device, to the board on the same side of the star coupler. The output from the board on this side is returned to both the main node device and the sub node device. The output signals of the main node device and the sub node device are mixed once in a star coupler and then distributed to each device. This allows each device to receive transmission signals from all devices including itself.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a configuration diagram for explaining the transmission method of the first embodiment.

In this embodiment, both the signal from the main node device l and the signal from the sub node device 2 are input to the board on the same side of the star coupler 3, and the output from the board on the other side is input to the main node device l. and the secondary node device 2. The star coupler 3 is installed near the sub-node device 2. Therefore, the distance from the main node device f to the star coupler 3 is relatively long, and the distance from the star coupler 3 to the sub node device 2 is relatively short.

Regarding the transmission from the main node device 1 to the sub-node device 2, there is no need to control the transmission because it is a broadcast type transmission with only one transmitting device. In addition, for transmission from the sub-node device 2 to the main node device l, since the transmission capacity of the optical fiber 4 is sufficiently large, Briasain TDMA is used.
This method makes it possible to allocate sufficient transmission capacity to each main node device l. In addition, the main node device 1 and the sub node device 2
For transmission, lights of different wavelengths λl and λ2 are used. Therefore, even if both transmit at the same time, no signal collision will occur. The star coupler 3 once mixes these transmission signals and distributes them to each device.

With such a configuration, each device can receive transmission signals from all devices including itself.

Note that this embodiment can be implemented by using light sources with different wavelengths as the transmitting means of the main node device 1 and the sub node device 2, and by using a normal star coupler 3 and optical fiber 4.

FIG. 2 is a configuration diagram for explaining a second embodiment of the present invention.

In the case of this embodiment, each sub-node device 2 is doubly attached to two main node devices 1. The two main node devices 1 transmit using lights of different wavelengths λ1 and λ3, so that signal collision does not occur even if they transmit at the same time. Main node device 1
Both the signal from the main node device 1 and the signal from the sub node device 2 are input to the board on the same side of the star coupler 3, and the output from the board on the other side is returned to both the main node device 1 and the sub node device 2. The star coupler 3 is installed near the sub-node device 2. Therefore, the distance from the main node device 1 to the star coupler 3 is relatively long, and the distance from the star coupler 3 to the sub node device 2 is relatively short.

In this method, the increase in cost on the subscriber side is smaller than when each sub-node device 2 belongs to a single main node device f. Furthermore, since each sub-node device 2 belongs to two main node devices I, only a single main node device! It is possible to provide more services and is more resilient to failures than if the network were to belong to a network. Further, in the case of this embodiment, it is possible to implement it by using light sources with different wavelengths as the transmitting means of the main node device 1 and the sub node device 2, and by using a normal star coupler 3 and optical fiber 4.

〔Effect of the invention〕

Since the optical fiber transmission system of the present invention mixes the output signals of the main node device and the sub node device once in the star coupler and then distributes them to each device, it can produce the following effects.

(2) Transmission between sub node devices can be performed without going through the main node device.

- Broadcast communication from one sub-node device to all other sub-node devices can be performed without going through the main node device.

■Since all signals sent by each device return to the source, it is easy to detect disconnections in the optical fibers.

■Logically, both the main node device and the sub node device are connected to the bus equally, so in the event of a failure of the main node device, the sub node device can be connected as the main node device without changing the optical fiber connection. It can function as a node device.

■Since different wavelengths of light are used in the downstream direction from the main node device to the secondary node device and in the upstream direction from the secondary node device to the main node device, the upstream transmission capacity is not limited by the downstream traffic. .

■In the downstream direction, there is no need to control transmission.

[Brief explanation of the drawing]

FIGS. 1 and 2 are configuration diagrams for explaining different embodiments of the present invention, respectively. Figure 3(a) is a configuration diagram to explain a conventional transmission system that uses light of the same wavelength for upstream and downstream, and Figure 3(b) is a conventional transmission system that uses light of different wavelengths for upstream and downstream. FIG. 4 is a block diagram for explaining a conventional local area network. ■...Main node device, 2...Secondary node device Mi3...Star coupler, 4...
...Fiber end. Applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] A main node device, a sub node device, a star coupler,
In a transmission system that consists of optical fibers that connect them, and sends and receives signals between the main node device and the sub-node devices, and between the sub-node devices, the main node device and the star coupler, and each sub-node device. The devices and star couplers are connected using multiple optical fibers, and the transmission outputs of the main node device and sub node device are both input to one board of the star coupler, and the outputs from the other board of the star coupler are connected. The output is returned to both the main node device and the sub node device, and the signals from the main node device and the sub node device to the star coupler, and the signals from the star coupler to the main node device and the sub node device are sent using separate optical fibers. An optical fiber transmission system characterized in that light of different wavelengths is used for transmission from a main node device to a sub node device and for transmission between the sub node device and the main node device and between the sub node devices.