KR20190016281A - Method and Apparatus for Detecting a Disconnected Optic Fiber Line and a Location of Disconnection in Ring Optical Network System - Google Patents

Abstract

Disclosed are a method and an apparatus for detecting a disconnected optic fiber line and a disconnection location in a ring optical network system. The present invention relates to a method for detecting a disconnection location in a wavelength division multiplexing (WDM) optical communication network system in which a central office terminal and a plurality of remote terminals are connected in an optical ring network structure. The method for detecting a disconnection location includes: generating a disconnection monitoring signal having a predetermined disconnection monitoring frame in a device within a premise; converting the disconnection monitoring signal into an optical signal through a digital optical device of the device within the premise; allowing the apparatus within the premise to bidirectionally transmit the disconnection monitoring signal, which is converted into the optical signal, through an optical line of the optical ring network; and allowing the apparatus within the premise to calculate the disconnection location by analyzing a frame of the optical signal received bidirectionally through the optical line in the optical ring network.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting disconnection and disconnection in an optical network system of a ring network structure,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to an optical network system of a ring network structure, and more particularly, to a method of detecting whether or not a wire break occurs in an optical network system of a ring network structure.

The contents described in this section merely provide background information on the present embodiment and do not constitute the prior art.

In the LTE communication system, a method of separating the base station into a digital unit (DU) and a remote unit (RU) and installing the base station at a remote location is generally applied. In this base station architecture, as DU is centralized, several RUs are connected to one DU. In this case, WDM type front hole (Fronthaul) equipment is used between DU and RU to reduce the optical fiber cost, and line redundancy method is applied to stabilize the equipment operation.

In the implementation of such a WDM front-end equipment, the construction of a remote terminal (RT) using a passive optical device, which is easy to install and has fewer obstacles and fewer defects, has been gradually expanded. However, in the case of a remote device using a passive device, it is difficult to grasp the installation position thereof, and it is difficult for the operator to accurately recognize the installation position in the event of a failure. For this purpose, it is not cost effective to operate OTDR (Optical Time Domain Reflectometer) equipment at all times, and it is not time efficient to check OTDR from the first or end of optical line after failure. There is a need for a cost-effective and time-efficient way to prepare for a failure situation, such as a beam line break.

In the conventional OTDR method, the operator can not determine the disconnection position even though he knows the optical ring network structure. In order to find the disconnection position, it moves to the first or last end of the optical line between the node and the node, The failure recovery time is increased. On the other hand, when the OTDR is connected to all the lines at all times in order to reduce the failure recovery time, there is a problem that the expensive construction and operation cost of the OTDR must be increased.

The main object of the present embodiment is to provide a method capable of detecting a broken wire immediately after a broken wire occurs in an optical ring network system without using expensive equipment and detecting the broken wire.

According to an embodiment of the present invention, in a WDM (Wavelength Division Multiplexing) optical network system in which a Central Office Terminal and a plurality of remote terminals are connected in an optical ring network structure, A method of detecting a disconnection monitoring signal in an optical line terminal of an optical line terminal, a method of detecting a disconnection monitoring signal in an optical line terminal, A process of bidirectionally transmitting a disconnection monitoring signal through an optical line of an optical ring network and a process of calculating the disconnection position by analyzing the characteristics of an optical signal received bidirectionally through the optical line of the optical ring network And detecting the disconnection position.

In one embodiment of the present invention, a single line monitoring signal including a series of time stamps is generated by connecting a plurality of single line monitoring frames having a predetermined length with a separate time stamp capable of distinguishing each frame.

According to another embodiment of the present invention, there is provided an apparatus for detecting a disconnection position in an optical network system connected with an optical ring network structure, comprising: a signal generator for generating a disconnection surveillance signal; a signal conversion unit for converting the disconnection surveillance signal into an optical signal; A signal for detecting a disconnection and calculating a disconnection position by analyzing a characteristic of an optical signal received in both directions via the optical line, And a disconnection position detecting device including a processing section.

As described above, according to the present embodiment, a disconnection monitoring signal is transmitted from an apparatus in an internal office without analyzing the disconnection position manually, and the signal received through the ring network is analyzed to detect a disconnection immediately when disconnection occurs And the disconnection position can be grasped.

FIG. 1 is a diagram illustrating a mobile communication system in which an apparatus in an office and a plurality of remote devices according to an embodiment of the present invention are connected through an optical line to an optical ring network structure.
FIG. 2 is a view showing a part of the configuration of an apparatus and an apparatus for national office according to an embodiment of the present invention.
3 is a diagram showing a configuration of a disconnection detecting unit according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating a frame structure of a single wire monitoring signal according to an embodiment of the present invention. Referring to FIG.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. Throughout the specification, when an element is referred to as being "comprising" or "comprising", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise . In addition, '... Quot ;, " module ", and " module " refer to a unit that processes at least one function or operation, and may be implemented by hardware or software or a combination of hardware and software.

FIG. 1 is a diagram illustrating a mobile communication system in which an apparatus in an office and a plurality of remote devices according to an embodiment of the present invention are connected through an optical line to an optical ring network structure. In the figure, a mobile communication system using a Baseband Unit (BBU) and a Remote Radio Head (RRH) is shown. The BBU is connected to the mobile communication network through a backhaul, the BBU and the RRH are connected to each other through a front hole (Fronthaul), and the RRH is connected to the terminal through radio.

A signal transmitted between the BBU and the RRH in the mobile communication system according to an exemplary embodiment of the present invention is transmitted to an optical ring network including a Central Office Terminal (COT) 100 and a plurality of remote terminals (RT) (optical ring network). The device 100 is connected to the BBU and transmits signals of the backhaul mobile communication network. The plurality of remote devices 200 are directly connected to the RRH or connected to the RRH through a sub-RTT (SRT) And transmits a signal of RRH.

In an embodiment of the present invention, the device 100 and the plurality of remote devices 200 are connected in a ring shape via one optical line, and the device 100 is connected to a plurality of remote devices 200 through bidirectional communication . A plurality of remote devices 200 are passive nodes configured by passive elements and distribute signals transmitted from the device 100 or RRH in the ring network.

That is, the intra-state apparatus 100 transmits a down-link signal to the remote apparatuses 210, 220, 230, and 240 in both directions, and the remote apparatuses 210, 220, 230, up-link signal to the intra-state-space apparatus 100. Accordingly, the intra-state apparatus 100 can receive the uplink signals from the remote apparatuses 210, 220, 230 and 240 in both directions via the optical line, and can receive the bidirectionally received remote apparatuses 210, 220, 230, 240 to sense the distance to each of the remote units 210, 220, 230, and 240, and the interval in which the failure has occurred.

Specifically, in an embodiment of the present invention, the intra-state apparatus 100 wavelength-division multiplexes a signal to be transmitted to each of the remote devices 210, 220, 230, and 240 and transmits the signal in both directions. Each of the remote devices 210, 220, 230, and 240 distributes a signal of a wavelength allocated thereto from the multiplexed signals to a sub-remote device (for example, SRT31 or SRT32 in the drawing) or an RRH directly connected to each remote device do. Each of the remote devices 210, 220, 230, and 240 has a switch therein and uses only one of bidirectional signals.

On the other hand, in the optical ring network according to the embodiment of the present invention, since uplink or downlink signal transmission is performed in both directions, even if a failure occurs in the optical line in any of the connected optical lines, Each remote device 210, 220, 230, 240 may receive a downlink signal from the device 100 within the home office.

Hereinafter, a method for determining whether or not the disconnection of the optical line has occurred in the optical ring network environment as described in Fig. 1 and detecting the disconnection position will be described. Although the present embodiment describes a front-hole network of a mobile communication system as an example, the present invention can also be applied to an optical network system having a ring network structure.

FIG. 2 is a view showing a part of the configuration of an apparatus and an apparatus for national office according to an embodiment of the present invention.

The in-state apparatus 100 is connected to a plurality of remote devices 200 in a ring-like manner and transmits signals in both directions. Referring to FIG. 2, the apparatus 100 for domestic office includes a wavelength multiplexer / demultiplexer (MUX / Demux) 160 and a single wire detecting unit 180. The wavelength multiplexers / demultiplexers 160 and 170 include a first wavelength multiplexer / demultiplexer 160 that transmits a signal in the EAST direction according to a direction in which signals are transmitted, and a second wavelength multiplexer / demultiplexer 160 that transmits a signal in the WEST direction. (170).

The wavelength multiplexers / demultiplexers 160 and 170 wavelength-division multiplex the downlink signal and the single wire supervisory signal, and transmit the multiplexed signal to a plurality of remote devices 200. In addition, signals received from a plurality of remote devices 200 are demultiplexed by wavelength band.

The first wavelength multiplexer / demultiplexer 160 multiplexes signals to be transmitted in the EAST direction to a plurality of remote devices 200 connected in a circular manner. Specifically, the first wavelength multiplexer / demultiplexer 160 multiplexes the downlink signal and the single line supervisory signal of the 1625 nm band. As shown in FIG. 2, the first wavelength multiplexer / demultiplexer 160 multiplexes the disconnection monitoring signal in the 1625 nm band with the downlink signal and transmits the multiplexed signal in the EAST direction.

The second wavelength multiplexer / demultiplexer 170 multiplexes / demultiplexes signals to be transmitted in the WEST direction to a plurality of remote devices 200 connected in a circular manner. Specifically, the second wavelength multiplexer / demultiplexer 170 multiplexes the downlink signal and the line monitoring signal in the 1625 nm band. Likewise, the second wavelength multiplexer / demultiplexer 170 multiplexes the disconnection monitoring signal in the 1625 nm band with the downlink signal and transmits it in the WEST direction.

3 is a diagram showing a configuration of a disconnection detecting unit according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating a frame structure of a single wire monitoring signal according to an embodiment of the present invention. Referring to FIG.

The disconnection detecting unit 180 generates a disconnection detecting signal, analyzes the disconnection detecting signal received through the ring network, detects a disconnection, and calculates a disconnection position. The disconnection detecting unit 180 is connected to the wavelength multiplexing / demultiplexing units 160 and 170 and transmits and receives a disconnection detection signal using the 1625 nm band. Specifically, the disconnection detecting section 180 may include a disconnection monitoring signal generating section 181, a disconnection monitoring signal converting section 182, and a disconnection monitoring signal processing section 183.

The disconnection surveillance signal generator 181 generates a disconnection surveillance signal including the disconnection surveillance frame. The disconnection monitoring signal is used only for disconnection detection and disconnection position detection as a signal transmitted to the ring network in order to determine whether a disconnection occurs in the optical line and its position when a disconnection occurs. Specifically, the disconnection monitoring signal can be composed of a plurality of disconnection monitoring frames having a predetermined length. Each disconnection monitoring frame can include a time stamp in the overhead area of the frame so that each frame can be distinguished. have. That is, the disconnection monitoring signal generated by the disconnection monitoring signal generator 181 may be configured to include a series of time frames having a predetermined time interval as shown in FIG.

The disconnection supervisory signal conversion unit 182 is implemented using a digital optical element of the device 100 in the indoor unit 100 and converts the disconnection supervisory signal into an optical signal.

The disconnection monitoring signal processing section 183 transmits the disconnection monitoring signal converted into the optical signal in both directions of the optical ring network. The single line supervisory signals converted into optical signals are multiplexed at a frequency of 1625 nm band through wavelength multiplexers / demultiplexers 160 and 170, and are transmitted in the EAST direction and the WEST direction. The disconnection supervision signals transmitted in the EAST direction and the WEST direction have the same time interval with a series of time stamps, and are simultaneously transmitted in each direction.

The disconnection monitoring signal processing unit 183 processes the optical signal received by the internal-apparatus 100 through the ring network. Specifically, the disconnection monitoring signal processor 183 receives the optical signal of the 1625 nm band from the wavelength multiplexers / demultiplexers 160 and 170, analyzes the characteristics of the received optical signal, and determines whether the disconnection occurs or not, Processing is performed. At this time, the disconnection monitoring signal transmitted in the EAST direction is received in the WEST direction, and the disconnection monitoring signal transmitted in the WEST direction is received in the EAST direction. Signals transmitted simultaneously in each direction are simultaneously received within an error range, and the error can be corrected by applying an offset.

The disconnection monitoring signal processing section 183 can calculate the total distance of the entire optical ring network using the difference between the transmission time and the reception time of the disconnection surveillance signal. The total distance of the entire optical ring network can be calculated using the difference between the transmission time and the reception time of the flux and disconnection monitoring signals of the glass medium constituting the optical line. Further, the disconnection monitoring signal processing section 183 can calculate the delay time of the entire optical ring network using the length of the disconnection monitoring frame. At this time, the delay time can be expressed by the number of time stamps existing in the optical line of the optical ring network at an arbitrary point in time. For example, assuming that the length of a predetermined single line monitoring frame is 1 us and the light flux of the glass medium is 5 us / km, there are a maximum of 75 time stamps in an optical line of 15 km at an arbitrary point in time, Can be calculated as 75 us.

The disconnection monitoring signal processing unit 183 can calculate the disconnection position by analyzing the characteristics of the optical signal received in both directions through the optical line of the optical ring network. In the case where a disconnection occurs in the optical line, the apparatus 100 for internal-office use analyzes the characteristics of the optical signal to be able to detect that the disconnection has occurred and also detects the disconnection based on the reception time of the optical signal received in both directions The position can be calculated. If the optical line signal is broken, the signal path will be anomalous. Therefore, if the characteristics of the optical signal received by the apparatus 100 in the state of national office are analyzed, a bit error, a sync error, a pattern error, a frame error , A loss of frame (LOF), and a loss of signal (LOS). When the characteristics of the optical signal received through the optical ring network are confirmed in the apparatus 100, the disconnection position can be calculated by comparing the detected times received and detected in both directions. For example, when a bit error is first detected in a signal received in the WEST direction and then a bit error is detected in a signal received in the EAST direction, a bit error is received in each of the WEST and EAST directions, It is possible to calculate the distance difference from the disconnection point and calculate the position where the disconnection occurred in the signal path of the ring network. The phenomenon that may occur due to the disconnection described above is merely an example, and various phenomena other than the described phenomenon may occur. If a disconnection occurs in the optical line, the optical signal passing through the disconnection point reflects this phenomenon. The position where the disconnection occurred can be calculated.

In addition, the disconnection monitoring signal processor 183 analyzes frames of optical signals received in both directions through the optical line of the optical ring network, and if a time stamp is not received in any direction, disconnection occurs in the optical line It can be judged. In the case where the optical line is normally operated, since the wireline monitoring signal processing unit 183 receives the time stamp at a predetermined time interval, the wireline monitoring signal processing unit 183 receives the wireline monitoring signal including a series of time stamps at predetermined intervals do. However, when a disconnection occurs in the optical line, the reception of the time stamp stops in either direction of the bidirection, and the reception of the other direction stops soon. Accordingly, when the frame of the received optical signal is analyzed, if the timestamp is not included, it is determined that the line disconnection occurs somewhere in the optical line and the disconnection surveillance signal transmitted from the apparatus in the inside office 100 does not normally pass through the ring network do.

The disconnection monitoring signal processing unit 183 analyzes a frame of the optical signal received in both directions through the optical line of the optical ring network to calculate the disconnection position. Specifically, the number of timestamps contained in frames of optical signals received in different directions is compared to calculate the disconnection position. For example, assuming that the length of a predetermined single wire monitoring frame is 1 us and the light flux of the glass medium is 5 us / km, there are a maximum of 75 time stamps in an optical line of 15 km at an arbitrary point in time. When 65 timestamps are received in the WEST direction from the time point at which the timestamp received at a certain time interval is no longer received in the EAST direction, a delay time of 65us is detected in the WEST direction signal rather than the EAST direction signal . Since the total number of timestamps that can be included in the optical line at the instant of time is 75, the total delay time is 75us and the delay time in both directions must be taken into consideration. Therefore, a point 5us away from the EAST direction (70 us away from the WEST direction) Can be calculated. That is, it can be seen that a disconnection occurred at a point 1 km away from the EAST direction (14 km away from the WEST direction).

In this manner, the single-line supervisory signal having a series of time stamps is converted into an optical signal by using an inexpensive digital optical device of an in-house apparatus and transmitted in both directions to the ring network and the frame of the received signal is analyzed, And it can be detected by the simple calculation. Therefore, it is effective to manage the broken line of the optical line in terms of cost and time.

The above description is merely illustrative of the technical idea of the present invention, and various modifications and changes may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments are not intended to limit the scope of the present invention but to limit the scope of the technical idea of the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: Local device 200: Multiple remote devices
180:

Claims (13)

A method for detecting a disconnection position in a WDM (Wavelength Division Multiplexing) optical communication network system in which a Central Office Terminal and a plurality of remote terminals are connected in an optical ring network structure,
Generating a predetermined disconnection monitoring signal in an apparatus within the national office;
Converting the disconnection monitoring signal into an optical signal through a digital optical device of the apparatus in the state of the art;
A step of bidirectionally transmitting a disconnection monitoring signal, which is converted into an optical signal, by the apparatus in the office of national government through an optical line of an optical ring network; And
A step of calculating the disconnection position by analyzing the characteristics of the optical signal received bidirectionally through the optical line of the optical ring network
And detecting the disconnection position. The method according to claim 1,
The total distance of the optical ring network is calculated by comparing the transmission time of the disconnection surveillance signal transmitted in the one direction by the device within the state of art and the reception time of the optical signal received in the other direction through the optical ring network process
And detecting a disconnection position. The method according to claim 1,
The calculation process may include:
Wherein the disconnection position is calculated by comparing the detected time when the phenomenon due to the disconnection is detected in both directions when a phenomenon due to disconnection is detected by analyzing characteristics of the received optical signal. The method according to claim 1,
Wherein the transmitting comprises:
And the two disconnection monitoring signals identical to each other are simultaneously transmitted in both directions. The method according to claim 1,
Wherein the generating comprises:
Wherein a single line monitoring signal including a series of time stamps is generated by connecting a plurality of single line monitoring frames of a predetermined length having separate time stamps capable of distinguishing each frame. 6. The method of claim 5,
The calculation process may include:
And calculating the disconnection position by comparing the number of time stamps included in optical signals received in different directions. 6. The method of claim 5,
The calculation process may include:
Calculating a maximum number of time stamps that can be included in the optical line at a certain moment using the length of the single wire monitoring frame and the light flux of the glass medium in the optical line;
Checking the number of additional time stamps received from the time when the optical line signal is no longer received in one direction of the bidirectional direction when no optical signal is received in any one of the two directions; And
Calculating the disconnection position using the maximum number of time stamps and the number of additional time stamps
And detecting a disconnection position. An apparatus for detecting a disconnection position in an optical network system connected by an optical ring network structure,
A signal generator for generating a disconnection monitoring signal;
A signal converter for converting the disconnection monitoring signal into an optical signal; And
A signal processing unit for transmitting a single line supervisory signal converted into an optical signal in both directions through an optical line of an optical ring network and for analyzing characteristics of an optical signal received in both directions through the optical line to detect a disconnection,
And the disconnection position detecting device. 9. The method of claim 8,
The signal processing unit,
The total distance of the optical ring network is calculated by comparing the transmission time of the disconnection surveillance signal transmitted in the one direction by the device within the state of art and the reception time of the optical signal received in the other direction through the optical ring network And wherein the disconnection position detecting device detects the disconnection position. 9. The method of claim 8,
The signal processing unit,
Wherein the disconnection position detecting unit calculates the disconnection position by comparing the detected time when the phenomenon due to the disconnection is detected in both directions when a phenomenon due to disconnection is detected by analyzing characteristics of the received optical signal. 9. The method of claim 8,
Wherein the signal generator comprises:
Line monitoring signal including a series of timestamps is generated by connecting a plurality of single-line monitoring frames of a predetermined length having separate timestamps capable of distinguishing each frame. 12. The method of claim 11,
The signal processing unit,
And calculates the disconnection position by comparing the number of time stamps included in optical signals received in different directions. 11. The method of claim 10,
The signal processing unit,
Calculating a maximum number of time stamps that can be included in the optical line at a certain moment using the length of the single wire monitoring frame and the light flux of the glass medium in the optical line;
Checking the number of additional time stamps received from the time when the optical line signal is no longer received in one direction of the bidirectional direction when no optical signal is received in any one of the two directions; And
Calculating the disconnection position using the maximum number of time stamps and the number of additional time stamps
The position detecting means detects the position of the wire.

Images