CN116349163A

CN116349163A - System and method for real-time monitoring of fiber performance

Info

Publication number: CN116349163A
Application number: CN202080105961.2A
Authority: CN
Inventors: 谢崇进; 陈赛; 窦亮; 张欢
Original assignee: Alibaba Group Holding Ltd
Current assignee: Alibaba Group Holding Ltd
Priority date: 2020-11-12
Filing date: 2020-11-12
Publication date: 2023-06-27
Also published as: WO2022099552A1

Abstract

One embodiment described herein provides a system for monitoring performance of an optical fiber in an optical transport network. The system may include a plurality of Optical Time Domain Reflectometer (OTDR) modules and an OTDR control and management module coupled to the plurality of OTDR modules. Each OTDR module is embedded in a network element of the optical transmission network and coupled to a fiber segment. The OTDR control and management module configures each OTDR module to monitor in real time the performance of the coupled fiber segment, which may include: detecting a fault in the coupled fiber segment, and identifying a location of the detected fault.

Description

System and method for real-time monitoring of fiber performance

Technical Field

The present disclosure relates generally to real-time monitoring of fiber performance. More particularly, the present disclosure relates to a system for monitoring optical fibers using Optical Time Domain Reflectometer (OTDR) based techniques.

Background

An Optical Transport Network (OTN) comprises a set of optical Network Elements (NEs) connected by optical fibre links and is capable of providing transport, multiplexing, switching, management, supervision and survivability functions of the optical channels carrying the client signals. The fiber links connecting the NEs play an important role in OTN. Performance degradation (caused by intrusion or degradation of fiber quality) of the fiber link typically results in degradation of the entire OTN.

Typically, fiber links are inspected to identify faulty fibers only after a system failure or significant performance degradation. Such a process can be very time consuming and sometimes results in long service outages.

Disclosure of Invention

One embodiment described herein provides a system for monitoring performance of an optical fiber in an optical transport network. The system may include a plurality of Optical Time Domain Reflectometer (OTDR) modules and an OTDR control and management module coupled to the plurality of OTDRs. Each OTDR module is embedded in a network element of the optical transmission network and connected to the fiber segments. The OTDR control and management module configures each OTDR module to monitor in real time the performance of the coupled fiber segment, which may include: detecting a fault in the coupled fiber segment, and identifying a location of the detected fault.

In a variant of this embodiment, the OTDR control and management module is located on a network control and management platform of the optical transport network.

In a variation of this embodiment, the OTDR control and management module configures each OTDR module to operate in one of the following modes: a fiber characterization (characterization) mode for characterizing the coupled fiber segments; an optical fiber fault detection mode for detecting faults in the coupled optical fiber segments; and an optical fiber fault identification mode for identifying a location of the detected fault.

In another variation, when operating in the fiber characterization mode, each OTDR module is configured to inject optical pulses having a first pulse width into the coupled fiber segment; when operating in the fiber fault detection mode, each OTDR module is configured to inject optical pulses having a second pulse width into the coupled fiber segment, the second pulse width being greater than the first pulse width; when operating in the fiber fault identification mode, each OTDR module is configured to inject optical pulses having a third pulse width into the coupled optical fiber segment, the third pulse width being greater than the first pulse width but less than the second pulse width.

In another variation, each OTDR module is configured to generate an output by calculating an average of a first number of measurements when operating in the fiber characterization mode; when operating in the fiber fault detection mode, each OTDR module is configured to generate an output by calculating an average of a second number of measurements, the second number being smaller than the first number; when operating in the fiber fault identification mode, each OTDR module is configured to generate an output by calculating an average of a third number of measured values, the third number being smaller than the first number but larger than the second number.

In another variation, the OTDR control and management module configures each OTDR module to operate in the fiber characterization mode after initial installation of the coupled fiber segment and before the coupled fiber segment is put into service.

In another variant, the OTDR control and management module is configured to: when each OTDR module operates in the fiber characterization mode, receiving OTDR measurements from each OTDR module, extracting information related to characteristics of the coupled fiber segment based on the received OTDR measurements, and storing the information related to characteristics of the coupled fiber segment in the fiber database.

In another variation, the OTDR control and management module configures each OTDR module to operate in a fiber fault detection mode after the coupled fiber segment is put into service.

In another variation, the OTDR control and management module switches each OTDR module from operating in the fiber fault detection mode to operating in the fiber fault identification mode in response to detecting a fault in the coupled fiber segment.

In a variant of this embodiment, the OTDR control and management module is configured to determine the optimal operating parameters for each OTDR module when operating in different modes.

In another variant, the OTDR control and management module is configured to store the determined optimal operating parameters in a look-up table and index the look-up table using unique identifiers assigned to the plurality of OTDR modules.

In a variant of this embodiment, the fiber segments are coupled to additional OTDR modules embedded in adjacent network elements.

Drawings

Fig. 1 is a diagram illustrating an exemplary Optical Transport Network (OTN) with an embedded Optical Time Domain Reflectometer (OTDR) module in accordance with one embodiment.

FIG. 2A illustrates an exemplary unidirectional fiber monitoring scenario according to one embodiment.

FIG. 2B illustrates an exemplary bi-directional fiber monitoring scenario according to one embodiment.

Fig. 2C illustrates exemplary OTDR measurements according to one embodiment.

FIG. 3 is a flowchart illustrating an exemplary process for real-time fiber performance monitoring, according to one embodiment.

Fig. 4 illustrates a block diagram of an exemplary embedded OTDR module, according to one embodiment.

Fig. 5 illustrates a block diagram of an exemplary centralized OTDR control and management module, according to one embodiment.

FIG. 6 illustrates an exemplary computer system, according to one embodiment.

In the drawings, like reference numerals refer to like elements.

Detailed Description

The following description is presented to enable one of ordinary skill in the art to make and use the embodiments and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the disclosure. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

Overview of the invention

The disclosed embodiments provide an optical fiber monitoring system capable of automatically monitoring the performance of an optical fiber in real time. The fiber monitoring system may include a plurality of Optical Time Domain Reflectometer (OTDR) modules distributed among various Network Elements (NEs) in an Optical Transport Network (OTN), and an OTDR management unit. In one embodiment, each NE in the network comprises an edge NE and an inline NE, each NE in the network may be equipped with an OTDR module such that each fiber segment can be monitored/measured by at least one OTDR module. Depending on the measurement requirements, each OTDR may be configured (e.g., by an OTDR management module) to operate in one of three different modes of operation, including a fiber characterization mode, a fiber fault detection mode, and a fiber fault identification mode. When operating in the fiber characterization mode, the OTDR module is configured to perform OTDR measurements at a higher spatial resolution but at a lower speed. When operating in the fiber fault detection mode, the OTDR module is configured to perform OTDR measurements at a lower spatial resolution but at a higher speed. Based on the high resolution OTDR measurements, the system may determine the optimal OTDR parameters for each fiber segment and store these parameters in a look-up table for future use. When operating in the fiber fault identification mode, the OTDR module is configured to perform OTDR measurements at a spatial resolution between a higher resolution and a lower resolution and at a speed between a higher speed and a lower speed. More specifically, after detecting a failure or fault on a particular fiber segment, the OTDR management unit may perform a table lookup to retrieve the optimal OTDR parameters for that particular segment. The OTDR parameters may then be used to perform OTDR measurements as well as OTDR data analysis.

Real-time optical fiber performance monitoring system

Optical Time Domain Reflectometry (OTDR) is an instrument that measures spatially resolved reflectance and loss in an optical fiber. The working principle of the OTDR is as follows: a series of light pulses is injected into the fiber under test and light scattered (rayleigh back-scattered) or reflected back from points along the fiber is extracted from the same end of the fiber. The collected scattered or reflected light is used to characterize the fiber. This corresponds to the way in which an electronic time domain reflectometer measures the reflection caused by the impedance change of the cable under test. The intensity of the return pulse is measured and integrated as a function of time and plotted as a function of fiber length.

In conventional approaches, OTDR (which may include a handheld unit or a desktop unit) is typically used to diagnose an optical fiber (e.g., locate a failed optical fiber) after a network fails. These approaches fail to meet the current telecommunication network requirements that network operators are expected to provide services to subscribers with minimal disruption. It is desirable to be able to detect and locate faults (e.g., fiber breaks) at the moment they occur to expedite service recovery. To facilitate real-time monitoring of fiber performance, in some embodiments, the OTN may include a plurality of OTDR modules embedded in the NE. Each embedded OTDR module may continuously monitor the fiber segments connected (interface) with the corresponding NE (e.g., by performing OTDR measurements). Thus, any degradation in performance of the fiber can be identified and reported in time to ensure that service disruption caused by fiber failure is minimized.

Fig. 1 is a diagram illustrating an exemplary Optical Transport Network (OTN) with an embedded Optical Time Domain Reflectometer (OTDR) module in accordance with one embodiment. In fig. 1, OTN 100 comprises a plurality of Network Elements (NEs) including terminal NE 102 and terminal NE 104, and an in-line NE 106, an in-line NE 108, and an in-line NE 110. The termination NE may include electrical layer devices such as optical transponders, as well as optical layer devices such as multiplexers/demultiplexers, termination optical amplifiers (e.g., erbium Doped Fiber Amplifiers (EDFAs)) and Reconfigurable Optical Add Drop Multiplexers (ROADMs). The inline NE may include an inline optical amplifier (e.g., an EDFA) as well as a ROADM. In some embodiments, each NE in OTN 100 may include an embedded OTDR module. For example, terminal NE 102 and terminal NE 104 include an embedded OTDR module 112 and an embedded OTDR module 114, respectively. The OTDR module embedded in the terminal NE may be part of the terminal optical amplifier or ROADM module. Similarly, the in-line NE 106, the in-line NE 108, and the in-line NE 110 include an embedded OTDR module 116, an embedded OTDR module 118, and an embedded OTDR module 120, respectively. The OTDR module embedded in the in-line NE may be part of an in-line optical amplifier or ROADM module. The embedded OTDR module may be designed to be compact to accommodate a variety of optical layer devices.

The OTN 100 may further comprise a control and management module 122, which control and management module 122 can be coupled to each OTDR module. More specifically, each OTDR module may be equipped with a control interface, and the control and management module 122 may send control signals to each OTDR module through the control interface to set the operating parameters of the OTDR module. In addition to receiving control signals, the embedded OTDR may also send measurement results to the control and management module 122 via the control interface.

Some OTDR modules may operate in a unidirectional manner, meaning that each fiber segment has one OTDR module coupled, and the OTDR module sends and receives test pulses from one end of the fiber segment. The transmitted OTDR test pulse may be co-propagating (co-propagating) or counter-propagating (counter-propagating) with the optical data signal carried by the fiber segment. FIG. 2A illustrates an exemplary unidirectional fiber monitoring scenario according to one embodiment. In fig. 2A, each fiber segment is coupled to one OTDR module and OTDR test pulses co-propagate with the data signals in the fiber segment. The OTDR module may be configured to monitor the performance of the coupled fiber segment. For example, while NE 204 itself is coupled to both fiber segment 206 and fiber segment 208, OTDR 202 embedded in NE 204 is coupled only to fiber segment 206. During operation, the OTDR 202 may be configured to inject test pulses (as indicated by the arrows) into the fiber segment 206 (which test pulses co-propagate with the optical data signals carried by the fiber segment 206) and to receive backscattered light from the fiber segment 206. By analyzing the backscattered light received by the OTDR 202 (more specifically, by calibrating the speed of the pulse as it passes through the fiber, measuring the time, calculating the position of the pulse in the fiber, and correlating the intensity of the backscattered light with the actual position in the fiber), conditions of the fiber can be inferred, such as detecting losses distributed along the fiber length, fiber breaks, or overstresses caused by sharp turns. In the example shown in fig. 2A, NE 204 is an amplifier site (site) and includes an inline amplifier 210.NE 204 may also be a ROADM site that includes ROADM modules.

Some OTDR modules may operate in a bi-directional manner, meaning that a single fiber segment may be coupled with two OTDR modules, each injecting and receiving test pulses to and from one end of the fiber segment, and the two OTDR modules work in concert. FIG. 2B illustrates an exemplary bi-directional fiber monitoring scenario according to one embodiment. In fig. 2B, each NE may include two OTDR modules, one of which is used to monitor the performance of a particular (downstream or upstream) fiber segment. For example, the OTDR 212 and the OTDR 214 embedded in the NE 216 may be coupled with an upstream fiber segment 218 and a downstream fiber segment 220, respectively, both of which are connected with the NE 216. During operation, the OTDR 212 may be configured to inject test pulses into the fiber segment 218 (as indicated by the arrow alongside the fiber 218) and receive backscattered light from the fiber segment 218. In this scenario, the injected test pulse counter-propagates with the data signal in the fiber optic segment 218. By analyzing the backscattered light, information about the condition of the fiber segment 218 may be obtained. Similarly, the OTDR 214 may be configured to inject test pulses into the fiber segment 220 (as indicated by the adjacent arrows) and receive backscattered light from the fiber segment 220. Alternatively, each fiber segment may be monitored by two OTDR modules, one at each end of each fiber segment. In the example shown in fig. 2B, fiber segment 220 is monitored by OTDR 214 and OTDR 222 embedded in

adjacent NEs

216 and 224, respectively. The measurements from the two OTDR modules may be combined (e.g., averaged) to provide more accurate information about the fiber segment 220. This bi-directional operation may be achieved by configuring the downstream OTDR module and the upstream OTDR module to use different wavelengths. Alternatively, one OTDR module may be used in one NE, and the switch may be configured to alternately use the OTDR modules when monitoring two fiber segments.

Fig. 2C illustrates an example graph of example OTDR measurements according to one embodiment. In fig. 2C, OTDR 222 injects test pulses into fiber 224 and receives back-scattered light from fiber 224. The intensity of the backscattered light at different fiber positions may be plotted as a curve 226, which curve 226 is also referred to as OTDR trace (trace). As can be seen from fig. 2C, the optical power of the received light decreases with the length of the fiber due to the round-trip fiber attenuation. Moreover, various components within the optical fiber 224 (e.g., connectors, splicers, etc.) may also result in loss of optical power. Furthermore, each connector also produces a reflection peak due to fresnel reflection, wherein the height of the peak indicates the amount of reflection at the connector location. As shown in fig. 2C, the ends of the fibers typically produce a high reflection peak due to fresnel reflection. By analyzing the curve 226, important information about the condition of the optical fiber 224 can be obtained. For example, the overall slope of curve 226 indicates an attenuation coefficient of the optical fiber, and an abnormally high attenuation coefficient may indicate a problem in optical fiber 224. If the fiber 224 is damaged, a peak indicating the end of the fiber will appear in the curve 226 at a position closer to the OTDR 222 than the length of the fiber 224. If excessive stress is applied to the fiber 224 due to a kink or sharp turn, additional loss (e.g., similar to the loss of the splicer) will occur at locations in the curve 226 where the splicer is absent.

In order for the OTDR measurements to provide accurate results (e.g., curve 226 shown in fig. 2C), the operational parameters of the OTDR (e.g., test range, wavelength, pulse width, and average number) need to be carefully selected. The test range is the distance that the OTDR will measure. In general, the test range should be twice the length of the fiber under test. Longer ranges may result in lower spatial resolution and shorter ranges may create distortion in the OTDR trace. The wavelength of the test pulse is typically determined by the type of fiber under test. Multimode optical fibers are used to carry optical signals in the 850nm and 1300nm bands; therefore, OTDR measurements for multimode fibers should be performed in the 850nm or 1300nm band. On the other hand, single-mode optical fibers are used to carry optical signals in the 1300nm and 1550nm bands, and therefore OTDR measurements for single-mode optical fibers should be performed in the 1300nm or 1550nm bands. It should be noted that shorter wavelengths (e.g., 850 or 1300 nm) may produce more backscatter and provide a higher signal-to-noise ratio (SNR). Thus, it may be desirable to perform an initial OTDR measurement on an optical fiber using a shorter wavelength and then perform an additional OTDR measurement on the optical fiber using a longer wavelength. The results from both wavelengths can be used to evaluate the condition of the fiber.

The pulse width is the duration of each test pulse. Longer pulses may provide a larger dynamic range but lower spatial resolution for the OTDR. Longer pulses also mean that a greater amount of optical power will be injected into the fiber and thus can propagate farther along the fiber. On the other hand, shorter pulses may provide higher spatial resolution, but require longer time to obtain adequate SNR due to reduced backscatter.

Data points obtained from a single test pulse may vary in level from one to the next even though the pulses from which the data points come have little variation. The resulting OTDR measurements (e.g., OTDR traces) may have noise. To improve SNR, the OTDR may send thousands of test pulses per second. Each test pulse provides a set of data points, which are then averaged together with the subsequent set of points to improve the SNR of the measurement. The parameter of the average number refers to the number of measurements (e.g., the number of pulses) used to calculate the average to improve the SNR. A large number of averages may provide a better SNR but may require a longer time to complete.

Based on the requirements (e.g., whether the test is to characterize the fiber or detect faults) and characteristics (e.g., type, length, number of bends, etc.) of the fiber, different operating parameters are required to produce optimal OTDR measurements. In a conventional setting, the operating parameters of the OTDR may be set manually by an operator. However, these methods do not meet the requirements of real-time fiber monitoring systems. Automatic parameter settings are required.

In some embodiments, the control and management module may be configured to automatically set the operating parameters of each OTDR module. More specifically, the OTDR control and management module (which may be part of the network control and management platform of the OTN) may determine the operating parameters of the embedded OTDR module based on the test scenario and the characteristics of the fiber under test. The OTDR control and management module may also send control signals to the embedded OTDR module to set the operating parameters of the embedded OTDR module.

In some embodiments, depending on the test scenario, the embedded OTDR module may be configured to operate in one of three modes of operation: fiber characterization mode, fiber fault detection mode, and fiber fault identification mode. More specifically, the parameter space may be divided into three regions, each region corresponding to a particular mode of operation.

When an optical fiber is first installed, it is desirable to find detailed characteristics of the optical fiber, including the length of the optical fiber, loss tangent, various loss inducing elements (e.g., connectors and splicers), etc. Such information may be important for a network administrator to evaluate the performance of the OTN and manage power distribution within the OTN. Further, when the optical fiber is first installed, the embedded OTDR module coupled to the optical fiber is configured to operate in the fiber characterization mode to obtain detailed information about the characteristics of the optical fiber. More specifically, when operating in the fiber characterization mode, the embedded OTDR module is configured to perform OTDR measurements using a high spatial resolution. To configure the embedded OTDR module, the OTDR control and management module may send control signals to the embedded OTDR module to set the pulse width to a relatively small number. To obtain the highest resolution, the pulse width may be set to as small a number as possible, which may be a few nanoseconds. To ensure adequate SNR, the average number of times will be set to a large number (e.g., hundreds of times). It should be noted that the measurement speed is not critical when operating in the fiber characterization mode. Thus, a particular region in the parameter space corresponding to the fiber characterization mode may have a smaller pulse width but a larger average number of times.

After the fiber is put into service, the embedded OTDR may be placed in a fiber fault detection mode to detect a fault of the fiber once it has occurred in the fiber. In this mode of operation, the measurement speed is the main concern, which means that a small average number of times is desired. Thus, the spatial resolution will be lower (i.e., longer pulses will be used). When placing the embedded OTDR in the fiber fault detection mode, the OTDR control and management module may send control signals to set the pulse width to a relatively large value (e.g., tens or hundreds of nanoseconds) and the average number of times to a small number (e.g., several times). In general, the pulse width used in the fiber fault detection mode may be much larger (e.g., several orders of magnitude) than the pulse width used in the fiber characterization mode. On the other hand, the number of average times used in the fiber fault detection mode may be much smaller (e.g., several orders of magnitude) than the number of average times used in the fiber characterization mode. The specific region in the parameter space corresponding to the fiber fault detection mode may have a larger pulse width but a smaller average number of times. In one example, when operating in a fiber fault detection mode, the embedded OTDR may be configured to simply measure the end-to-end loss of the coupled fiber by injecting a single long pulse into the fiber, and without the need to calculate an average value.

When an OTDR measurement from a particular embedded OTDR module indicates a fault (e.g. excessive loss of optical fiber or breakage of optical fiber is detected), the OTDR control and management module may be triggered to send a control signal to the particular embedded OTDR module to switch the operation mode of the particular embedded OTDR module from an optical fiber fault detection mode to an optical fiber fault identification mode in order to obtain more detailed location information related to the fault, thereby facilitating the network operator performing an optical fiber repair operation at the identified fault location. In order to be able to identify the location of the fault in time, the OTDR module needs to consider both the spatial resolution and the measurement speed. In other words, the pulse width cannot be too large to ensure adequate spatial resolution, and cannot be too small to ensure a moderate number of required average times. When switching the embedded OTDR to operate in the fiber fault identification mode, the OTDR control and management module may send a control signal to set the pulse width and the average number of times to a value between the fiber characterization mode and the fiber fault detection mode. That is, the pulse width is greater than that used in the fiber characterization mode, but less than that used in the fiber fault detection mode. On the other hand, the average number of times is smaller than that used in the fiber characterization mode, but is larger than that used in the fiber fault detection mode. Accordingly, the specific region corresponding to the optical fiber failure recognition mode in the parameter space may be located between the specific region corresponding to the optical fiber characterization mode and the specific region corresponding to the optical fiber failure detection mode. This ensures that the fault location is identified quickly and accurately.

In addition to the different modes of operation, the operating parameters of the embedded OTDR may also depend on the characteristics of the optical fiber coupled to the OTDR. For example, fibers having different lengths require different test ranges to be set. Although the length of a typical fiber segment may be between 80 and 100 kilometers, the fiber segment may be shorter or longer depending on the actual scenario. Optical fibers with different attenuation parameters may require different pulse widths and/or average times. In order to provide optimal settings for each OTDR in each mode of operation, the OTDR control and management module may obtain optimal operating parameters for each embedded OTDR module in each mode of operation and store these optimal operating parameters in a look-up table, which is indexed by the identifier of the embedded OTDR module. When an embedded OTDR module needs to set its parameters (e.g. when the embedded OTDR module switches from one mode of operation to a different mode of operation), the OTDR control and management module may perform a table lookup to obtain the optimal parameters of the embedded OTDR and send control information to the embedded OTDR to set its operating parameters accordingly. In addition to the OTDR operating parameters, the various data processing parameters (e.g., the specific algorithms or filter parameters used) used by the OTDR control and management module to process the original OTDR data may also be specific to the fiber under test.

Various algorithms may be used to determine the optimal OTDR measurement parameters and data processing parameters for each fiber segment. In some embodiments, these parameters may be obtained by calculation. More specifically, assuming that the fiber characteristics (e.g., length, attenuation coefficient, etc.) are known, optimal or sub-optimal OTDR measurement parameters and/or data processing parameters may be calculated based on a particular linear or non-linear relationship between the fiber characteristics and the parameters. In some embodiments, these parameters may be obtained experimentally. For example, after first installing the fiber, the OTDR control and management module may configure the coupled OTDR to scan a parameter space to obtain optimal operating parameters of the OTDR in all three different modes. The data processing parameters may be obtained by similar methods.

FIG. 3 is a flowchart illustrating an exemplary process for real-time fiber performance monitoring, according to one embodiment. During operation, a fiber segment is installed within an OTN and coupled with an OTDR module embedded in a NE connected to the fiber segment (operation 302). The fiber segment may be part of a new extension of the OTN, or a replacement of a failed fiber segment. The NE may be a terminating NE or an inline NE depending on the location of the fiber segment itself in the OTN.

Before the fiber segment is put into service, the system determines optimal OTDR measurement parameters and data processing parameters (operation 304), and stores the determined parameters in a lookup table (operation 306). As previously described, the optimal parameters may be determined by performing calculations or scanning a parameter space. The optimal algorithm for processing the raw OTDR data may be determined based on previous experience. The look-up table may be indexed using unique identifiers assigned to individual OTDR modules. If the OTDR module is bidirectional, two sets of parameters will be stored in the table, one for each module at both ends of the fiber segment. The look-up table may be maintained by an OTDR control and management module, which may be located on a control and management platform of the OTN.

The OTDR control and management module may also place the OTDR module coupled to the fiber segment in a fiber characterization mode to obtain detailed characteristics of the fiber (operation 308) and store the fiber characteristics into a fiber database (operation 310). In some embodiments, the operations for determining the optimal parameters and for determining the characteristics of the optical fiber may be performed in an iterative manner. In other words, the optimal parameters determined in operation 304 may be used in operation 308 to set the operational parameters of the OTDR, and the fiber characteristics obtained in operation 308 may be used to update the optimal parameters determined in operation 304.

Thereafter, the fiber is put into normal use and the OTDR control and management module may also put the OTDR module coupled to the fiber segment into a fiber fault detection mode to continuously monitor the performance (especially the overall loss) of the fiber (operation 312). Based on the OTDR measurement results, the OTDR control and management module may determine whether a fiber fault is detected (operation 314). In some embodiments, the system detects a fault if the loss in the fiber exceeds a predetermined threshold or a fiber break is detected (e.g., the end of the fiber is closer to the OTDR than the fiber length).

If no fault is detected, the OTDR continues to monitor the fiber (operation 312). If a fault is detected, the OTDR control and management module may switch the operating mode of the OTDR module to a fiber fault identification mode to identify the exact location of the fault (operation 316). For example, if a fiber breaks, the OTDR may determine the exact location of the fiber break when operating in the fiber fault identification mode. Furthermore, if excessive stress (e.g., kinking or sharp turns) results in abnormal loss in the fiber, the OTDR can determine the exact location where the stress occurred. Based on the identified location, the network operator may perform the necessary repair on the failed fiber (operation 318). It should be noted that after the fiber is repaired, the fiber characteristics may change. Therefore, the optimal operating parameters will need to be recalibrated (operation 304).

Fig. 4 illustrates a block diagram of an exemplary embedded OTDR module, according to one embodiment. The embedded OTDR module 400 may comprise a control interface 402, a mode configuration unit 404, a pulse generator 406, a transmitter 408, a receiver 410 and a signal processing unit 412.

The control interface 402 enables the centralized OTDR control and management module to send control signals to the embedded OTDR module 400. The control signal may be used to place the OTDR module 400 in one of three modes of operation. In one embodiment, the control signal may also include various OTDR measurement parameters. In addition, the OTDR measurements (e.g., raw data) may also be sent to a centralized OTDR control and management module through control interface 402. The mode configuration unit 404 may configure the OTDR module 400 to operate in one of three operation modes based on the received control signal. In one embodiment, the mode configuration unit 404 may set various operating parameters of the OTDR module 400. Standard techniques for transmitting control and management signals in OTNs may be used for communication between the centralized OTDR control and management module and the OTDR module. For example, an Optical Supervisory Channel (OSC) signal may be used to carry control signals as well as OTDR measurements.

The pulse generator 406 may be configured to generate test pulses. The width of the test pulse is determined based on parameters provided by a centralized OTDR control and management module. The transmitter module 408 may transmit test pulses to the fiber under test. In some embodiments, the emitter module 408 may include lasers of different wavelengths. The receiver module 410 may receive back-scattered light from the fiber under test. The signal processing unit 412 may process the raw OTDR measurement data, including calculating an average of the output of the receiver 410 over a plurality of test pulses, performing fiber loss calculations, and identifying reflection points. The number of average times is determined based on parameters provided by the centralized OTDR control and management module. The output of the signal processing unit 412 may be sent to a centralized OTDR control and management module through the control interface 402.

Fig. 5 illustrates a block diagram of an exemplary centralized OTDR control and management module, according to one embodiment. The centralized OTDR control and management module 500 may comprise a control interface 502, an OTDR mode determining unit 504, a data processing unit 506, an OTDR parameter optimization and fiber characterization unit 508, a fiber fault detection unit 510, a fiber fault identification unit 512, a look-up table 514, and a fiber database 516.

The control interface 502 enables the centralized OTDR control and management module 500 to connect with a plurality of OTDR modules embedded in a plurality of NEs within the OTN. The centralized OTDR control and management module 500 may send control signals to each of the embedded OTDRs to configure the operation mode of the embedded OTDR and set the operation parameters of the embedded OTDR. Furthermore, the centralized OTDR control and management module 500 may receive OTDR measurements from the OTDR module through the control interface 502.

The OTDR mode determining unit 504 may determine an operation mode of the embedded OTDR based on the test requirements. The OTDR mode determining unit 504 may determine that the OTDR should be in the fiber characterization mode if the OTDR is measuring a newly installed and not yet in use fiber. If the OTDR is monitoring an optical fiber carrying data, the OTDR should be in a fiber fault detection mode. If a fault is detected in the fiber, the OTDR should be in fiber fault identification mode.

The data processing unit 506 may be configured to process and analyze OTDR data transmitted from OTDR modules in various NEs embedded in the ONTs. The data may be raw data from an OTDR module or pre-processed data from an OTDR module. Preprocessing the raw data at the OTDR module may reduce the amount of data sent from the OTDR module to the OTDR control and management module. On the other hand, in order to reduce the size or energy consumption of the OTDR module, the OTDR module may not perform a specific data processing task (e.g., pre-process the raw data). By analyzing the OTDR data provided by a particular OTDR module, information about the optical fiber being measured by the particular OTDR may be determined, including characteristics of the optical fiber or fault conditions of the optical fiber.

The OTDR parameter optimization and fiber characteristics characterization unit 508 determines the optimal measurement parameters and data processing parameters of the individual OTDR modules and the characteristics of the fiber under test. The optimal parameters may be determined based on the calculation or measurement results. The optical fiber fault detection unit 510 may detect a fault in an optical fiber based on the output of the data processing unit 506. For example, a sudden power outage may indicate a fault. Similarly, the fiber fault identification unit 512 may identify the location of the fault in the fiber based on the output of the data processing unit 506. For example, the location of the fiber break may be identified based on the location of the reflection at the fiber end.

The look-up table 514 stores the optimal OTDR measurement parameters and data processing parameters for each embedded OTDR module. In some embodiments, each embedded OTDR module may be assigned a unique identifier and these identifiers may be used to index the look-up table 514. In some embodiments, the directions of the bidirectional OTDR module may be assigned different identifiers. The fiber database 516 may store characteristics of each fiber segment being measured.

FIG. 6 illustrates an exemplary computer system, according to one embodiment. Computer system 600 includes a processor 602, memory 604, and storage 606. In addition, computer system 600 may be coupled to peripheral input/output (I/O) user devices 610 such as a display device 612, a keyboard 614, and a pointing device 616. Storage 606 may store operating system 618, real-time fiber monitoring system 620, and data 640.

The real-time fiber optic monitoring system 620 can include instructions that, when executed by the computer system 600, can cause the computer system 600 or the processor 602 to perform the methods and/or processes described in this disclosure. Specifically, the real-time fiber monitoring system 620 may include instructions for operating the control interface (control interface module 622), instructions for determining an operation mode of the embedded OTDR (OTDR mode determining module 624), instructions for processing OTDR measurements (OTDR data processing module 626), instructions for determining optimal measurement parameters and data processing parameters and fiber characteristics (OTDR parameter optimization and fiber characteristics description module 628), instructions for detecting faults in the fiber based on the processed OTDR data (fiber fault detection module 630), and instructions for identifying the location of the detected faults (fiber fault identification module 632).

In summary, embodiments of the present application provide a solution for accurately monitoring fiber performance in real time. By embedding compact OTDR modules in each NE of the OTN, the disclosed embodiments enable the OTDR modules to continuously monitor the performance of the data-carrying optical fibers. A centralized OTDR control and management module located on the network control and management platform may remotely configure the individual OTDRs to ensure that they are operating in the desired mode. By storing the optimal operating parameters of the individual OTDR modules in a look-up table, the centralized OTDR control and management module can ensure fast and accurate OTDR measurements, thus facilitating fast fiber fault diagnosis and repair. It should be noted that the operation modes of the OTDR module are not limited to the three modes disclosed in the present application. In practice, the OTDR module may have fewer or more modes of operation.

The methods and processes described in the detailed description section may be embodied as code and/or data, which may be stored in a computer-readable storage medium as described above. When the computer system reads and executes the code and/or data stored in the computer readable storage medium, the computer system performs the methods and processes embodied as data structures and code and stored in the computer readable storage medium.

Furthermore, the methods and processes described above may be implemented in digital electronic circuitry, or in computer software, firmware, or hardware. The hardware modules or apparatus may include, but are not limited to, application Specific Integrated Circuit (ASIC) chips, field Programmable Gate Arrays (FPGAs), special purpose or shared processors that execute a particular software module or piece of code at a particular time, and other programmable logic devices now known or later developed. When the hardware modules or devices are activated, they perform the methods and processes contained therein.

The techniques described above may be implemented using one or more computer program products. The programmable processor and computer may be contained in or packaged as a mobile device. The processes and logic flows can be performed by one or more programmable processors or by one or more programmable logic circuits. The general purpose and special purpose computing devices and the storage devices may be interconnected by a communication network.

The foregoing description of the various embodiments has been presented only for the purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Furthermore, the above disclosure is not intended to limit the present invention.

Claims

1. A system for monitoring performance of an optical fiber in an optical transport network, the system comprising:

a plurality of Optical Time Domain Reflectometer (OTDR) modules, wherein each OTDR module is embedded in a network element of the optical transmission network and coupled to an optical fiber segment; and

an OTDR control and management module coupled to the plurality of OTDR modules;

wherein the OTDR control and management module configures the respective OTDR module to monitor in real time the performance of the coupled fiber segment, the monitoring the performance of the coupled fiber segment comprising: detecting a fault in the coupled fiber segment, and identifying a location of the detected fault.

2. A system according to claim 1, wherein the OTDR control and management module is located on a network control and management platform of the optical transport network.

3. A system according to claim 1, wherein the OTDR control and management module configures the respective OTDR module to operate in one of the following modes:

a fiber characterization mode for characterizing the coupled fiber segment;

an optical fiber fault detection mode for detecting a fault in the coupled optical fiber segment; and

and an optical fiber fault identification mode for identifying the location of the detected fault.

4. The system of claim 3, wherein,

when operating in the fiber characterization mode, the respective OTDR module is configured to inject optical pulses having a first pulse width into the coupled fiber segment;

when operating in the fiber fault detection mode, the respective OTDR module is configured to inject optical pulses having a second pulse width into the coupled fiber segment, the second pulse width being greater than the first pulse width; and is also provided with

When operating in the fiber fault identification mode, the respective OTDR module is configured to inject optical pulses having a third pulse width into the coupled optical fiber segment, the third pulse width being greater than the first pulse width but less than the second pulse width.

5. The system of claim 3, wherein,

when operating in the fiber characterization mode, the respective OTDR module is configured to generate an output by calculating an average of a first number of measurements;

when operating in the fiber fault detection mode, the respective OTDR module is configured to generate an output by calculating an average of a second number of measured values, the second number being smaller than the first number; and is also provided with

When operating in the fiber fault identification mode, the respective OTDR module is configured to generate an output by calculating an average of a third number of measured values, the third number being smaller than the first number but larger than the second number.

6. A system according to claim 3, wherein the OTDR control and management module configures the respective OTDR module to operate in the fiber characterization mode after initial installation of the coupled fiber segment and before the coupled fiber segment is put into service.

7. The system of claim 6, wherein the OTDR control and management module is configured to:

receiving OTDR measurements from the respective OTDR module when the respective OTDR module is operating in the fiber characterization mode;

Extracting information related to characteristics of the coupled fiber segments based on the received OTDR measurements; and

information relating to characteristics of the coupled optical fiber segments is stored in an optical fiber database.

8. A system according to claim 3, wherein the OTDR control and management module configures the respective OTDR module to operate in the fiber fault detection mode after the coupled fiber segment is put into service.

9. A system according to claim 3, wherein the OTDR control and management module switches the respective OTDR module from operating in the fiber fault detection mode to operating in the fiber fault identification mode in response to detecting a fault in the coupled fiber segment.

10. A system according to claim 1, wherein the OTDR control and management module is configured to determine optimal operating parameters for the respective OTDR module when operating in different modes.

11. The system of claim 10, wherein the OTDR control and management module is configured to store the determined optimal operating parameters in a look-up table, and wherein the look-up table is indexed using unique identifiers assigned to the plurality of OTDR modules.

12. The system of claim 1, wherein the fiber segment is coupled to an additional OTDR module embedded in an adjacent network element.

13. A method for monitoring performance of an optical fiber in an optical transport network, the method comprising:

embedding a plurality of Optical Time Domain Reflectometer (OTDR) modules into a plurality of network elements in the optical transmission network, wherein each OTDR module is embedded into a network element and coupled to a fiber segment; and

configuring, by the OTDR control and management module, the plurality of OTDR modules, including: configuring the respective OTDR module to monitor in real time a performance of the coupled fiber segment, wherein monitoring the performance comprises: detecting a fault in the coupled fiber segment, and identifying a location of the detected fault.

14. A method according to claim 13, wherein the OTDR control and management module is located on a network control and management platform of the optical transport network.

15. The method of claim 13, wherein the respective OTDR modules are configured to operate in one of:

a fiber characterization mode for characterizing the coupled fiber segment;

16. The method of claim 15, wherein,

17. The method of claim 15, wherein,

18. The method of claim 15, wherein configuring the respective OTDR modules comprises: the individual OTDR modules are configured to operate in the fiber characterization mode after initial installation of the coupled fiber segment and before the coupled fiber segment is put into service.

19. The method of claim 18, the method further comprising:

20. The method of claim 15, wherein configuring the respective OTDR modules comprises: the individual OTDR modules are configured to operate in the fiber fault detection mode after the coupled fiber segment is put into service.

21. The method of claim 15, the method further comprising: in response to detecting a fault in the coupled fiber segment, switching the individual OTDR modules from operating in the fiber fault detection mode to operating in the fiber fault identification mode.

22. The method of claim 13, the method further comprising: and determining optimal operation parameters of each OTDR module when the OTDR modules operate in different modes.

23. The method of claim 20, the method further comprising: the determined optimal operating parameters are stored in a look-up table, and wherein the look-up table is indexed using unique identifiers assigned to the plurality of OTDR modules.

24. The method of claim 13, the method further comprising: an additional OTDR module is embedded in the network element, wherein the additional OTDR module is coupled to the second fibre segment.