KR102020578B1 - 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 for detecting disconnection and disconnection position in an optical communication network system having a ring network structure, and an optical communication network system using the same.
According to the present embodiment, a method for detecting a disconnection position 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 for generating a disconnection monitoring signal having a predetermined disconnection monitoring frame in a domestic device, the method comprising: generating a disconnection monitoring signal; Converting the disconnection monitoring signal into an optical signal through a digital optical device of the internal device; Transmitting, by the domestic device, a disconnection supervisory signal converted into an optical signal in both directions through an optical line of an optical ring network; And calculating the disconnection position by analyzing a frame of the optical signal received in both directions through the optical line of the optical ring network.

Description

Method for detecting disconnection and disconnection position in an optical network system having a ring network structure, and an apparatus for detecting disconnection using the same {Method and Apparatus for Detecting a Disconnected Optic Fiber Line and a Location of Disconnection in Ring Optical Network System}

The present invention relates to an optical communication network system having a ring network structure, and more particularly, to a method of detecting whether an optical line is disconnected and a location of a disconnection occurrence in an optical communication network system having a ring network structure.

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

In the LTE communication system, a base station is divided into a digital unit (DU) and a remote unit (RU) and installed in a long distance. In this base station structure, as DUs are centralized in one place, several RUs are connected to one DU. In this case, WDM fronthaul equipment is used between the DU and the RU to reduce the optical fiber cost, and a line duplication method is applied to stabilize the operation of the equipment.

In the implementation of such WDM fronthaul equipment, the construction of a remote terminal (RT) using a passive optical device that is easy to install and has few obstacles and defects is gradually expanding. However, in the case of a remote device using a passive element, it is difficult to determine the installation location, and it is difficult for an operator to accurately recognize this in case of a failure situation. Regular operation of Optical Time Domain Reflectometer (OTDR) equipment is not cost effective for this purpose, and it is not time efficient to identify OTDR from the very first or end of the line after failure. There is a need for an efficient method, both costly and timely, in case of a fault situation such as a line break.

In the existing OTDR method, even if the operator knows the structure of the optical ring network, the position of the disconnection cannot be determined. Therefore, the process of identifying the disconnection point through the OTDR by moving to the edge or end of the optical path between the nodes to find the disconnection location. Since it must be repeated, there is a problem that the failure recovery time increases. 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 in that the cost of constructing and operating the equipment increases because expensive OTDR must be operated all the time at all times.

This embodiment has a main object to provide a method in which an optical ring network system can detect a disconnection and even its position as soon as a disconnection occurs in an optical line without using expensive equipment.

According to an embodiment of the present invention, a disconnection position may be determined 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 detection method comprising: generating a predetermined disconnection monitoring signal in a device inside a country, converting the disconnection monitoring signal into an optical signal through a digital optical device of the device in the country, and converting the device within the country into an optical signal. Transmitting the disconnection monitoring signal in both directions through the optical line of the optical ring network; and calculating the disconnection position by analyzing the characteristics of the optical signal received in both directions through the optical line of the optical ring network. It provides a disconnection position detection method comprising.

In an embodiment of the present invention, a plurality of disconnection monitoring frames having a predetermined length having separate time stamps capable of distinguishing each frame are connected to generate a disconnection monitoring signal including a series of time stamps.

According to another embodiment of the present invention, an apparatus for detecting a disconnection position in an optical communication network system connected by an optical ring network structure, a signal generation unit for generating a disconnection monitoring signal, a signal conversion for converting the disconnection monitoring signal into an optical signal Signal for detecting disconnection and calculating disconnection position by transmitting disconnection monitoring signal converted into negative and optical signals in both directions through optical line of optical ring network, and analyzing the characteristics of optical signal received in both directions through the optical line Provided is a disconnection position detecting device including a processing unit.

As described above, according to the present embodiment, the operator detects disconnection as soon as disconnection occurs by transmitting a disconnection supervisory signal from a device in the office and analyzing the received signal through the ring network without the operator having to manually determine the disconnection position. And the location of the disconnection is effective.

1 is a diagram illustrating a mobile communication system in which a domestic device and a plurality of remote devices are connected in an optical ring network structure through an optical path according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a partial configuration of a domestic office device and a remote location device according to an embodiment of the present invention.
3 is a diagram illustrating a configuration of a disconnection detector according to an exemplary embodiment of the present invention.
4 is a diagram briefly illustrating a frame configuration of a disconnection monitoring signal according to an exemplary embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, in describing the component of this invention, terms, such as 1st, 2nd, A, B, (a), (b), can be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. Throughout the specification, when a part is said to include, 'include' a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated. . In addition, as described in the specification. The terms 'unit' and 'module' refer to a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software.

1 is a diagram illustrating a mobile communication system in which a domestic device and a plurality of remote devices are connected in an optical ring network structure through an optical path according to an embodiment of the present invention. In the drawings, a mobile communication system using a basebadnd unit (BBU) and a remote radio head (RRH) is shown. The BBU is connected to the mobile communication network through the backhaul, the BBU and the RRH are connected to each other through the fronthaul, and the RRH is connected to the terminal through the radio.

In the mobile communication system according to an embodiment of the present invention, a signal transmitted between a BBU and an RRH is an optical ring network including a central office terminal (COT) 100 and a plurality of remote terminal devices (RT) 200. relay through an optical ring network. The internal device 100 is connected to the BBU and transmits a signal of the backhaul mobile communication network, and the plurality of remote devices 200 are directly connected to the RRHs or connected to the RRHs through sub-RTs (SRTs). Send the signal of RRH.

In one embodiment of the present invention, the internal device 100 and the plurality of remote devices 200 are connected in a ring through a single optical path, the internal device 100 is bi-directional communication with the plurality of remote devices 200 Do this. The plurality of remote devices 200 are passive nodes composed of passive elements, and distribute signals transmitted from the in-house device 100 or the RRH in such a ring network.

That is, the internal device 100 transmits a downlink signal to the remote devices 210, 220, 230, and 240 in both directions, and the remote devices 210, 220, 230, and 240 transmit the uplink ( up-link) signal to the internal device 100. Accordingly, the internal device 100 may receive uplink signals from the remote devices 210, 220, 230, and 240 through the optical path in both directions, and receive the remote devices 210, 220, 230, which receive in both directions. By detecting the uplink signal of the 240, the distance to each of the remote devices 210 220, 230, and 240 and the section in which the failure occurs may be determined.

Specifically, in one embodiment of the present invention, the internal device 100 transmits in both directions by wavelength division multiplexing the signal to be sent to each remote device (210, 220, 230, 240). Each of the remote devices 210, 220, 230, and 240 splits a signal having a wavelength assigned to it among the multiplexed signals and distributes the signal to a sub-remote device (e.g., SRT31, SRT32 in the drawing) or an RRH directly connected to each remote device. do. Each remote device 210, 220, 230, 240 has a switch therein and uses only one of two-way signals.

On the other hand, in the optical ring network according to an embodiment of the present invention, since uplink or downlink signals are transmitted in both directions, even if a failure occurs in an optical path in any of the connected optical paths, the internal device 100 may be configured to provide a plurality of signals. An uplink signal may be received from the remote device 200, and each of the remote devices 210, 220, 230, and 240 may receive a downlink signal from the internal device 100.

Hereinafter, a method of determining whether disconnection of an optical line has occurred in an optical ring network environment as described in FIG. 1 and detecting a disconnection position will be described. This embodiment has been described taking the fronthaul network of the mobile communication system as an example, but may be applied to an optical communication network system having a ring network structure.

FIG. 2 is a diagram illustrating a partial configuration of a domestic office device and a remote location device according to an embodiment of the present invention.

The internal device 100 is connected to the plurality of remote devices 200 in a ring shape and transmits signals in both directions. Referring to FIG. 2, the internal device 100 includes a wavelength multiplexer / demultiplexer (Mux / Demux) 160 and 170 and a disconnection detector 180. The wavelength multiplexer / demultiplexer 160 and 170 may include a first wavelength multiplexer / demultiplexer 160 which transmits a signal in an EAST direction and a second wavelength multiplexer / demultiplexer which transmits a signal in a WEST direction according to a signal transmission direction. It is divided into 170.

The wavelength multiplexer / demultiplexer 160 and 170 wavelength division multiplex the downlink signal and the disconnection supervisory signal, and transmit the multiplexed signal to the plurality of remote devices 200. In addition, the signals received from the plurality of remote devices 200 are demultiplexed for each wavelength band.

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

The second wavelength multiplexer / demultiplexer 170 multiplexes / demultiplexes a signal to be transmitted in a WEST direction to a plurality of remote devices 200 connected in a circle. Specifically, the second wavelength multiplexer / demultiplexer 170 multiplexes the downlink signal and the disconnection supervisory signal of the 1625 nm band. Similarly, the second wavelength multiplexer / demultiplexer 170 multiplexes the 1625nm band disconnection supervisory signal with the downlink signal and transmits the signal in the WEST direction.

3 is a diagram illustrating a configuration of a disconnection detector according to an exemplary embodiment of the present invention.

4 is a diagram briefly illustrating a frame configuration of a disconnection monitoring signal according to an exemplary embodiment of the present invention.

The disconnection detection unit 180 generates a disconnection detection signal, analyzes the received disconnection detection signal after returning from the ring network, detects the disconnection, and calculates the disconnection position. The disconnection detection unit 180 is connected to the wavelength multiplexer / demultiplexer 160 and 170 and transmits and receives a disconnection detection signal using a 1625nm band. Specifically, the disconnection detecting unit 180 may include a disconnection monitoring signal generator 181, a disconnection monitoring signal converter 182, and a disconnection monitoring signal processor 183.

The disconnection monitoring signal generator 181 generates a disconnection monitoring signal including a disconnection monitoring frame. The disconnection monitoring signal is a signal transmitted to the ring network to determine whether disconnection has occurred in the optical line and, if disconnection occurs, and is used only for disconnection detection and disconnection location. Specifically, the disconnection monitoring signal may be composed of a plurality of disconnection monitoring frames having a predetermined length, and each disconnection monitoring frame may include a time stamp in an overhead area of the frame to distinguish each frame. have. That is, the disconnection monitoring signal generated by the disconnection monitoring signal generator 181 may be configured to include a series of timeframes having a predetermined time interval, as shown in FIG. 4.

The disconnection monitoring signal converter 182 is implemented using a digital optical device of the internal device 100 and converts the disconnection monitoring signal into an optical signal.

The disconnection monitoring signal processing unit 183 transmits the disconnection monitoring signal converted into an optical signal in both directions of the optical ring network. The disconnection supervisory signal converted into an optical signal is multiplexed at a frequency of 1625 nm band through the wavelength multiplexer / demultiplexer 160 and 170 and transmitted in the EAST direction and the WEST direction. The disconnection monitoring signal transmitted in the EAST direction and the WEST direction is the same signal, and a time interval of a series of time stamps is constant, and is simultaneously transmitted in each direction.

The disconnection supervisory signal processing unit 183 processes the optical signal received by the internal device 100 around the ring network. In detail, the disconnection monitoring signal processor 183 receives an optical signal having a band of 1625 nm from the wavelength multiplexer / demultiplexer 160 and 170 and analyzes the characteristics of the received optical signal to detect whether a disconnection occurs and a disconnection position. Perform the process. 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 processor 183 may calculate the total distance of the entire optical ring network by using the difference between the transmission time and the reception time of the disconnection monitoring 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 luminous flux and disconnection monitoring signal of the glass medium constituting the optical path. In addition, the disconnection monitoring signal processor 183 may calculate the delay time of the entire optical ring network using the length of the disconnection monitoring frame. In this case, the delay time may be represented by the number of timestamps present in the optical path of the optical ring network at any one point in time. For example, if the length of a predetermined disconnection monitoring frame is 1 us and the luminous flux of the glass medium is 5 us / km, a maximum of 75 time stamps exist on a 15 km optical path at any one time, and the delay time Can be calculated as 75 us.

The disconnection monitoring signal processor 183 may calculate the disconnection position by analyzing characteristics of the optical signal received in both directions through the optical line of the optical ring network. When disconnection occurs in the optical line, the internal device 100 may not only detect that the disconnection has occurred by analyzing the characteristics of the received optical signal, but also disconnection based on the reception time of the optical signal received in both directions. The position can be calculated. If a disconnection occurs in the optical line, an abnormality occurs in the signal path, so when analyzing the characteristics of the optical signal received by the internal device 100, unlike a normal received signal, Bit error, Sync error, Pattern error, Frame error Phenomena such as loss of frame (LOF) and loss of signal (LOS) are detected. In the internal device 100, when the characteristics due to such a phenomenon are confirmed in the optical signal received through the optical ring network, the disconnection position may be calculated by comparing the detection times detected by the corresponding phenomenon 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, and then the difference is detected. The distance difference from the disconnection point can be calculated and the location of the disconnection in the signal path of the ring network can be calculated. The phenomenon that may occur due to the disconnection described above is exemplary, and various phenomenon may occur in addition to the described phenomenon, and when the disconnection occurs in the optical line, the optical signal passing through the disconnection point reflects such a phenomenon. Using the difference in time, the position where the disconnection occurred can be calculated.

In addition, the disconnection monitoring signal processor 183 analyzes a frame of an optical signal received in both directions through the optical line of the optical ring network, and when the time stamp is no longer received in either direction, the disconnection occurs in the optical line. You can judge. When the optical line operates normally, since the internal device 100 transmits a disconnection monitoring signal including a series of time stamps at a predetermined interval, the disconnection monitoring signal processing unit 183 receives the time stamps at a predetermined time interval. do. However, when a disconnection occurs in the optical line, the reception of the time stamp stops in either direction, and the other direction soon stops receiving. Therefore, when the time stamp is not included by analyzing the frames of the received optical signal, disconnection occurs somewhere in the optical path, and it is determined that the disconnection monitoring signal transmitted from the internal device 100 does not normally pass through the ring network. do.

The disconnection monitoring signal processor 183 calculates a disconnection position by analyzing a frame of an optical signal received in both directions through an optical line of the optical ring network. Specifically, the disconnection position is calculated by comparing the number of time stamps included in frames of optical signals received in different directions. For example, if the length of a predetermined disconnection monitoring frame is 1 us and the luminous flux of the glass medium is 5 us / km, there are a maximum of 75 timestamps in the 15 km optical path at any one point in time. If the time stamps received at regular intervals are no longer received in the EAST direction and 65 more time stamps have been received from the WEST direction from that point on, it is understood that the delay time of 65us occurred in the WEST direction signal rather than the EAST direction signal. Can be. The total delay time is 75us because the maximum number of time stamps can be included in the optical line at a given moment is 75us, and the delay time in both directions should be taken into account, so 5us away from the EAST direction (70us away from the WEST direction). It can be calculated that disconnection has occurred at. That is, it can be seen that disconnection occurred at a point 1 km away from the EAST direction (14 km away from the WEST direction).

In this way, a single wire supervisory signal having a series of time stamps is converted into an optical signal using an inexpensive digital optical device of a domestic company, transmitted to the ring network in both directions, and the frame of the received signal is analyzed so that the signal is immediately disconnected. It is possible to check the occurrence and to detect the location through simple calculation, which is effective in managing the disconnection 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 those skilled in the art to which the present embodiment belongs may make various modifications and changes without departing from the essential characteristics of the present invention. Accordingly, the embodiments are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

100: domestic device 200: a plurality of remote devices
180: disconnection detection unit

Claims (13)

A method of detecting a disconnection position 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,
Generating a predetermined disconnection monitoring signal in an internal device;
Converting the disconnection monitoring signal into an optical signal through a digital optical device of the internal device;
Transmitting, by the domestic device, a disconnection supervisory signal converted into an optical signal in both directions through an optical line of an optical ring network; And
Calculating a disconnection position by analyzing a characteristic of an optical signal received in both directions through an optical line of the optical ring network, by the domestic device;
The process of generating,
Generating a disconnection monitoring signal including a series of time stamps by connecting a plurality of disconnection monitoring frames having a predetermined length having a separate time stamp for distinguishing each frame,
The process of calculating,
Calculating the number of timestamps that can be included in the optical line at a given time using the length of the disconnection monitoring frame and the light flux of a glass medium in the optical line;
When the optical signal is no longer received in any one of the two directions, confirming the number of additional time stamps additionally received from the time when the disconnection monitoring signal is no longer received in the other one of the two directions; And
And calculating the disconnection position by using the maximum number of timestamps and the additional timestamps. The method of claim 1,
Computing the total distance of the optical ring network by comparing the transmission time of the disconnection monitoring signal transmitted by the device in one direction with the reception time of the optical signal received through the optical ring network in one direction. process
Disconnection position detection method comprising a. The method of claim 1,
The process of calculating,
And analyzing the characteristics of the received optical signal to detect the phenomenon due to disconnection, and calculating the disconnection position by comparing the detection time at which the phenomenon due to the disconnection is detected in both directions. The method of claim 1,
The transmitting process,
A disconnection position detection method comprising transmitting two disconnection monitoring signals identical to each other simultaneously. delete The method of claim 1,
The process of calculating,
The disconnection position detection method of claim 1, wherein the disconnection position is calculated by comparing the number of time stamps included in optical signals received in different directions. delete 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 converting the disconnection monitoring signal into an optical signal; And
Signal processing unit for detecting the disconnection and calculating the disconnection position by transmitting the disconnection supervisory signal converted into the optical signal in both directions through the optical line of the optical ring network, and analyzing the characteristics of the optical signal received in both directions through the optical line Include,
The signal generator,
Generating a disconnection monitoring signal including a series of time stamps by connecting a plurality of disconnection monitoring frames of a predetermined length having separate time stamps to distinguish each frame,
The signal processing unit,
Calculating the number of timestamps that can be included in the optical line at a given time using the length of the disconnection monitoring frame and the light flux of a glass medium in the optical line;
When the optical signal is no longer received in any one of the two directions, confirming the number of additional time stamps additionally received from the time when the disconnection monitoring signal is no longer received in the other one of the two directions; And
Performing a process of calculating the disconnection position by using the maximum number of timestamps and the number of additional timestamps that can be included at the maximum;
Disconnection position detection device, characterized in that. The method of claim 8,
The signal processing unit,
A total distance of the optical ring network is calculated by comparing the transmission time of the disconnection monitoring signal transmitted in the one direction with the reception time of the optical signal received in the other direction through the optical ring network. Position detection device. The method of claim 8,
The signal processing unit,
And analyzing the characteristics of the received optical signal to detect the phenomenon due to disconnection, and calculating the disconnection position by comparing the detection time at which the phenomenon due to the disconnection is detected in both directions. delete The method of claim 8,
The signal processing unit,
The disconnection position detection device, characterized in that for calculating the disconnection position by comparing the number of timestamps included in the optical signals received in different directions. delete

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