KR100600696B1 - Optical communication network having a capability of switching to protection line by employing a reflective optical signal - Google Patents

Abstract

The present invention relates to an optical communication network having an optical switching function. An optical fiber protection line for bypassing and transmitting an optical signal as a reverse optical signal when cutting a pair of optical fiber operation lines and the optical fiber operation lines for each node of the present invention. Is connected. Means for transferring each input optical signal to a receiving node through the optical fiber operation line, and switching the input optical signal to bypass the reverse optical signal through the optical fiber protection line when the optical fiber operation line is cut. Characterized in that it comprises a.

Description

OPTICAL COMMUNICATION NETWORK HAVING A CAPABILITY OF SWITCHING TO PROTECTION LINE BY EMPLOYING A REFLECTIVE OPTICAL SIGNAL}

1 is a block diagram of an optical switching system using a reflected signal of the present invention;

FIG. 2 is a diagram illustrating the flow of an optical signal when cutting an optical fiber in the optical switching system shown in FIG.

<Description of the symbols for the main parts of the drawings>

110, 120, 130, 140: node 200: optical branch / combiner

220: optical rotating machine 230, 330: photodetector

240: connector 320: optical splitter

500: optical fiber operation line 600: optical fiber protection line

The present invention relates to a metro optical network in a metropolitan area in which optical communication between nodes is carried out through a light beam, and more particularly, when a fiber optic operation line between any nodes is cut in the optical network. The present invention relates to an optical communication network having an optical switching function capable of self-healing by switching to an optical fiber protection line.

In recent years, as the service demand of users increases, the slave channel transmission speed of a node in the optical communication network increases significantly in order to transmit a large amount of optical signal data. However, loss of optical signal data is caused when the optical path between any nodes is cut off. In order to solve this problem, research on ultra-high speed / capacity optical nodes in metropolitan areas has been actively conducted. Among them, many techniques have been proposed for bypassing signals when cutting with optical beams in optical wavelength branching / combining structures. .

One such method is described by Z. Yuxun, Z. QingJi, L. YuFeng, W. Kai in October 1999, OECC'99, CISI (98), "Self-Healing Mechanism in the WDM All Optical Metropolitan Network: SHAONET". It is a self-healing method of optical communication network announced under the name. In this paper, loopback of two nodes to a protection ring using a line protection ring or shared protection ring when an optical fiber is disconnected between any two nodes in an optical network in an urban area A structure for constructing a self-healing ring is disclosed. In the method of constructing the self-healing ring, the node in the direction of progression at the cut point can easily detect the presence or absence of power of the operation node, so if the power is not detected, the optical switch is protected by the cross state. The node in the opposite direction to be connected to the ring and to proceed with the cut point automatically configures the self-healing ring by connecting another optical switch to the operation ring with or without the power of the optical amplifier of the node to proceed. Done.

However, a disadvantage of the self-healing method described above is that an optical amplifier must be disposed between nodes. In other words, as the number of nodes increases, the number of optical amplifiers increases in proportion to each other. Therefore, even when the distance between nodes is short, an expensive optical amplifier for switching signals is used. .

Therefore, the present invention has been made to solve the above-described problem, and an optical communication having an optical switching function capable of detecting a switched optical path by using a reflected light signal when switching the optical path in an optical communication network and configuring a self-healing ring network. Its purpose is to provide a network.

An optical communication network having an optical switching function according to the present invention for achieving the above object includes: a plurality of nodes; An optical fiber operation line connected between each node and transferring an optical signal input from a sending node to a receiving node; An optical fiber protection line connected between the respective nodes, the optical fiber protection line bypassing and transmitting the optical signal of the sending node to the receiving node as a reverse optical signal when the optical fiber operation line is cut;

Each node may be configured to transfer the input optical signal to a receiving node through the optical fiber operation line, and the input optical signal may be diverted as the reverse optical signal through the optical fiber protection line when the optical fiber operation line is cut. And means for transferring the lock.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1A and 1B are block diagrams of an optical switching system using reflected signals in an optical communication network according to the present invention, and include a plurality of nodes 110, 120, 130, and 140, and respective nodes 110, 120, 130, It consists of an optical fiber operation line 500 and an optical fiber protection line 600 connecting each node 110, 120, 130, 140 via a connector 240 (see FIG. 2) provided between each 140.

The nodes 110, 120, 130, 140 each receive an optical signal converted from an electrical signal generated by the subscriber in connection with the optical subscriber transmission device (not shown) of the optical subscriber, and operate the optical signal to the subscriber. It performs the function of providing the desired destination node through the line 500. In the present invention, the nodes 110, 120, 130, and 140 may each serve as a receiving node for receiving an optical signal from a node in front of the node or a sending node for transmitting the received optical signal to a receiving node in a subsequent stage. Can be. At this time, the optical signal is transmitted by wavelength divisional multiplexing, and each node (110, 120, 130, 140) extracts the optical signal of the wavelength assigned to it, and transmits the optical signal received from the subscriber to itself. Transmit by multiplexing to the assigned wavelength

In general, when the optical paths connecting all the nodes operate normally, the optical signal reflected and returned through the operation line 500 is reflected by Rayleigh scattering caused by the unevenness of the core and cladding surface of the fiber constituting the optical path. It can be distinguished by reflection from the connector 240 connecting the photons. The reflection due to Rayleigh scattering is typically around 60dB, which is only 0.001% of the input optical power. The reflection in the connector 240 can be made small enough to be neglected by the current development of connector manufacturing technology and the development of fiber manufacturing technology. This can minimize the amount of reflected light at the connector by making the cross section of the connector 240 at a slight angle as is well known in the art.

The present invention protects the operation line 500 by detecting when the reflected light signal exceeds a predetermined level by using a characteristic in which the power of the reflected light increases due to Rayleigh scattering when the operation line 500 between nodes is cut. A passive protection ring network is configured to transfer an optical signal to a node receiving an optical signal through a reverse bypass route formed by switching to the line 600.

Each node 110, 120, 130, 140 shown in FIG. 1A has the same configuration, and therefore, FIG. 2 shows a detailed block diagram of any one of the nodes 110, 120, 130, 140. Illustrated. As shown, each node 110, 120, 130, 140 includes an optical add-drop multiplex (OADM) 200, a first optical switch 210, an optical rotor 220, An optical switch controller 230, a connector 240, a second optical switch 310, an optical splitter 320, and an optical switch controller 330 are provided.

The optical signal splitter / combiner 200 divides the optical signal received from the subscriber side into a wavelength division multiplexer and transmits the optical signal to the receiving node via the first optical switch 210 and receives the received optical signal via the second optical switch 310. The optical signal of the wavelength allocated to its node is selectively extracted from the optical signal and transmitted to the subscriber side or provided to the first optical switch 210.

The optical circulator 220 allows the reflected light to be transmitted to the first photodetector 230 rather than to the first optical switch 210.

The first optical switch 210 is composed of two 2 × 2 switches, each switch providing a connection path between the operation line 500 and the protection line 600, the control of the first optical switch controller 230 Equilibrium state that transmits the optical signal input below through the optical fiber operation line 500 or the optical fiber protection line 600 and cross state to transfer the input optical signal from the optical fiber operation line 500 to the protection line 600 It is switched.

The first photodetector 230 detects the power of the reflected light and performs a control to switch the first optical switch 210 to a cross state when the detected amount of light exceeds the reference level. The first photodetector 230 is composed of a photodiode 232, a comparator 234 and an amplifier 236. The photodiode 232 converts the reflected optical signal transmitted by the optical rotor 220 into an electrical signal, and the comparator 234 compares the level of the converted electrical signal with a reference level so that the level of the reflected optical signal is a reference level. If larger, a control signal for switching the first optical switch 210 to the cross state is generated. In this case, the amplifier 236 serves to provide power for the switching action of the second optical switch 310.

The optical splitter 320 distributes the optical signal input from the sending node to the second optical switch 310 and the optical switch controller 330.

The second optical switch 320 is composed of two 2 × 2 switches, each switch providing a connection path between the operation line 500 and the protection line 600, respectively, of the second optical switch controller 330 Equilibrium state that transmits the optical signal input under control through the operation line 500 or the protection line 600 and cross state which transfers the path of the input optical signal from the protection line 600 to the operation line 500 again. Is switched to.

The second photodetector 330 detects the power of the input optical signal and performs control to switch the second optical switch 310 to the cross state only when the detected amount of light does not reach the reference level. The second photodetector 330 is composed of a photodiode 332, a comparator 334 and an amplifier 336. The photodiode 332 converts the reflected optical signal provided from the optical rotator 220 into an electrical signal, and the comparator 334 compares the level of the converted electrical signal with a reference level when the level of the optical signal is smaller than the reference level. Generates a control signal for switching the second optical switch 310 to the cross state. In this case, the amplifier 336 serves to provide power for the switching action of the second optical switch 310.

On the other hand, the optical fiber operation line 500 is formed between any sending node and receiving node via the first optical switch 310 and the second optical switch 210 of each node 110, 120, 130, 140. It provides a path for transmitting the optical signal provided from the sending node to the receiving node. Similarly, the optical fiber protection line 600 is opposite to the optical fiber operation line 500 via the first optical switch 310 and the second optical switch 210 of each node 110, 120, 130, 140. Connected between any sending node and receiving node, when the optical fiber operation line 500 between any two nodes is cut, it is switched by the sending node and bypasses the receiving node to transmit the optical signal. Provide a reverse path.

The optical switching operation performed in the optical switching configuration of the optical network of the present invention having the above-described configuration is described as follows with reference to FIGS. 1A and 1B.

First, as shown in FIG. 1A, when the operation line 500 connecting all nodes operates normally, for example, an optical signal provided from or before the node 110 to the node 140. The case to convey is explained.

At the node 110, the optical signal input through the optical splitter / combiner 200 is transmitted to the operation line 500 via its first optical switch 210. At this time, since the reflected optical signal that is detected by being applied to the first optical switch controller 230 through the optical connector 240 and the optical rotor 220 is smaller than the reference level, the first optical switch 230 is the first optical switch. The balance is maintained as it is by the switch controller 230. Accordingly, the optical signal generated from the node 110 is input to the node 140 via the node 120 and the node 130.

On the other hand, at the node 140, the optical signal input from the previous node is distributed in the optical splitter 320 and transmitted to the second optical switch 310 and the second optical switch controller 330. At this time, the second optical switch controller 330 converts the optical signal input through the photodetector 332 into an electrical signal, and because the converted level is smaller than the reference level of the comparator 334, the second optical switch 310 ) In equilibrium. The optical branch / combiner 200 may extract a signal corresponding to its wavelength among the optical signals transmitted through the second optical switch 310 and transmit it to the subscriber, and also transmit the signal to the next node 110 through it. It can also be.

Then, on the contrary, as shown in FIG. 1B, the operation line 500 between the nodes 120 and 130 is transferred while transmitting the optical signal generated from the node 110 to the final destination node 140. The case where it cut | disconnects is demonstrated.

The optical signal generated at the node 110 is transmitted through the operation line 500 to the node 120, as described with reference to FIG. 1A.

At the node 120, the optical signal reflected from the cut operation line 500 is provided to the first optical switch controller 230 by the optical rotator 220 via the connector 240. In this case, since the reflected optical signal detected by the first optical switch controller 230 is larger than the reference level when the operation line 500 operates normally, the first optical switch 210 is controlled in a cross state. By this control, the optical signal is reversed as the reverse optical signal through the first optical switch 210 of the node 120, as indicated by the dotted line in FIG. 1B. It is communicated to the second switch 310 of the node 130 through 600.

On the other hand, at the node 130, due to the cutting of the operation line 500, the level of the optical signal input to the node 130 is reduced. The change in the input optical signal level is detected by the second optical switch controller 330 in the node 130 to switch the second optical switch 310 to the cross state. Accordingly, as shown by a dotted line in FIG. 1B, the optical signal passing through the second optical switch 330 of the node 130 again moves the operation line 500 along the switched cross path of the second optical switch 310. It is shown to be delivered to the final destination node 140 via.

As a result, the optical signal transmitted from the node 110 passes through the node 110 and the node 140 in the opposite direction through the protective line 600 of its first switch 230 which is switched to the cross state and then again to the node ( A self-healing ring network is formed which leads to the second optical switch 310 of the final destination node 140 in a bypass manner, which leads to the operation line 500 via the second optical switch 310 which is transferred to the cross state at 130. .

Likewise, if the protective line 600 is cut off, it will operate as described above except that the optical signal is bypassed only through the operating line 500.

Therefore, according to the present invention, the optical switching structure using the reflected signal in the optical communication network not only increases the efficiency of the optical communication network but also has an advantage in terms of cost because it does not require the use of an optical amplifier or a monitoring signal to monitor the line. .

Claims (3)

In an optical communication network, Multiple nodes; An optical fiber operation line connected between each node and transferring an optical signal input from a sending node to a receiving node; An optical fiber protection line connected between the respective nodes, the optical fiber protection line bypassing and transmitting the optical signal of the sending node to the receiving node as a reverse optical signal when the optical fiber operation line is cut; Each of these nodes is: Means for transferring the input optical signal to a receiving node through the optical fiber operation line, and switching the input optical signal to bypass the reverse optical signal through the optical fiber protection line when the optical fiber operation line is cut. Optical communication network having an optical switching function, characterized in that. The method of claim 1 wherein the transfer means is: A first optical switch switched to a balanced state for selectively transmitting the input optical signal through the operation line or a cross state for transmitting the input optical signal as the reverse optical signal through the protection line; A first optical switch controller for controlling the first optical switch to the equilibrium state or the cross state according to the level of the reflected optical signal generated when the optical fiber is cut; A second optical switch switched to a balanced state for transmitting the reverse optical signal to the first optical switch or to a cross state for transmitting the reverse optical signal as the input optical signal through the first optical switch; And a second optical switch controller for controlling the second optical switch to the equilibrium state or the cross state according to the optical signal level input when cutting the optical fiber. The method of claim 1, wherein the first optical switch control means: Photoelectric conversion means for converting the reflected optical signal into an electrical signal; Comparison means for comparing a level of an electrical signal of the reflected optical signal converted by the photoelectric conversion means with a first preset level; A controller for controlling the optical switch to be switched to the cross state when the comparison result of the comparing means is higher than the first preset level; The second optical switch control means is: Photoelectric conversion means for converting the input optical signal into an electrical signal; Comparison means for comparing the level of the electrical signal converted by the photoelectric conversion means with a second preset level; And a controller for controlling the optical switch to be switched to the cross state when the level of the electrical signal of the input optical signal is smaller than the second preset level as a result of the comparison by the comparing means. Optical communication network.

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