Passive optical network physical link monitoring system

Abstract

The utility model provides a passive optical network physical link monitoring system, which is provided with a pulse transmitting device, a coupling device and a detection device, the pulse transmitting device transmits optical pulses with different wavelengths, the wavelengths of the optical pulses correspond to n optical network units respectively, and the optical pulses are coupled to an optical distribution network through the coupling device, the detection device obtains the power and distance corresponding information of the optical pulses in the trunk line link and each branch optical fiber link, and can know the conditions of each position on the trunk line link and each branch optical fiber link. According to the application, the optical pulses with different wavelengths are used as monitoring signals to monitor the conditions of each optical fiber link and the trunk link respectively, potential threats of a physical link can be sensed in advance and early warning can be carried out, a fault point can be positioned in time after a sudden accident occurs, and daily maintenance and accident emergency repair of a passive optical network link are facilitated.

Description

Technical Field

[0001] The present application relates to a link monitoring system, and in particular to a passive optical network physical link monitoring system. Background Art

[0002] The distribution communication network is a key infrastructure for monitoring and controlling the distribution system. It connects various distribution equipment, sensors and monitoring systems through digital communication technology to monitor, manage and control the power distribution network to improve the reliability, efficiency and safety of the power system. Its main communication services include: real-time monitoring of distribution networks, remote control, fault detection and diagnosis, distributed power supply control, intelligent load management, etc. Passive Optical Network (PON) is a common fiber optic communication technology in distribution communication networks above 35kV, and is a form of power communication access network. It has the characteristics of distributed point-to-multipoint structure, TDM uplink and downlink separation, high bandwidth and high information security.

[0003] The passive optical network in the distribution communication network is mainly built on the 35kV or higher optical cables entering the city in the distribution network. However, the urban environment is complex, and underground optical cables are easily cut, squeezed or worn due to construction activities. Overhead optical cables may also be damaged by animal bites and natural disasters (such as storms or tree collapse), which in turn affects the transmission of power and power communication signals. In addition, due to the large number of control devices involved in the 35kV and above medium and high voltage distribution network, the organization of distribution communication business is complex. Therefore, the link monitoring and operation and maintenance of the passive optical network has become the main problem for the reliable operation of the distribution communication business. In particular, monitoring the physical link of each ONU separately is of great significance for evaluating the operation risk of the distribution network control business.

[0004] At present, passive optical network system link monitoring is mainly carried out from two aspects: performance data and physical link. Studies have shown that at least 80% of faults occur in the physical link of optical fiber. In terms of physical link monitoring, PON link monitoring technology evaluates the status of the network physical link through monitoring equipment and other passive devices deployed at the CO (central office end). It can identify and locate faults in optical fiber while PON is transmitting data, and can quickly respond to optical fiber faults and learn the cause and location of the faults when they occur.

[0005] However, the monitoring and operation of existing physical links still have the following problems:

[0006] (1) Star topology physical link fault identification and location are difficult. When only using the PON network management system data monitoring technology, after a fiber physical link fault occurs, it is impossible to distinguish the fault type and locate the fault location.

[0007] (2) After setting the protection topology and a single physical link fails, it is difficult to evaluate the operating risk of the ONU equipment. Due to the low real-time operation and maintenance of the distribution communication network, after forming a specific network protection topology, the single-line failure operation and maintenance repair cycle is long. At this stage, it is impossible to evaluate the operating risk of a single ONU. Summary of the invention

[0008] In order to solve the above problems in the prior art, the present application provides a passive optical network physical link monitoring system.

[0009] In order to achieve the above objectives, this application adopts the following technical solutions:

[0010] In a first aspect, the present application proposes a passive optical network physical link monitoring system, wherein the optical fiber link of the passive optical network physical link includes a first optical line terminal, an optical distribution network and n optical network units, wherein the optical distribution network includes n first unequal splitters, where n is an integer greater than or equal to 1; including:

[0011] A pulse transmitting device, the output end of which is connected to the output end of the first optical line terminal, and is used to transmit optical pulses of different wavelengths, the wavelengths of the optical pulses respectively corresponding to the optical network units, and the wavelengths of the optical pulses and the network communication signals of the optical network units do not overlap;

[0012] A coupling device, connected to the output end of the optical pulse transmitting device, for coupling the optical pulse into the optical distribution network;

[0013] The detection device, whose receiving end is connected to the output end of the first optical line terminal, is used to obtain the power and distance corresponding information of the optical pulses in the trunk link and the branch optical fiber links corresponding to each optical network unit, and complete the monitoring of each branch optical fiber link.

[0014] Preferably, it further comprises n first wavelength division multiplexers and n second wavelength division multiplexers;

[0015] The passive optical network physical link adopts a bidirectional hand-in-hand protection structure, and the backup optical fiber link includes a second optical line terminal and n second unequal splitters;

[0016] The input ends of the n first wavelength division multiplexers are respectively connected to the output ends of the n first unequal optical splitters, and the input ends of the n second wavelength division multiplexers are respectively connected to the output ends of the n second unequal optical splitters;

[0017] One output end of n first wavelength division multiplexers and n second wavelength division multiplexers are respectively connected to n optical network units, and the other output ends of the n first wavelength division multiplexers are respectively connected to the other ends of n second wavelength division multiplexers. The allowed passing wavelength of each first wavelength division multiplexer corresponds to the optical pulse emitted by the pulse emitting device, and the allowed passing wavelength of the first wavelength division multiplexer and the second wavelength division multiplexer connected to the same optical network unit is the same.

[0018] Preferably, it also includes an isolation device;

[0019] The isolation device is connected between the second optical line terminal and the first second unequal optical splitter.

[0020] Preferably, the detection device adopts OTD R .

[0021] Preferably, the pulse transmitting device and the detecting device jointly adopt T-OTDR.

[0022] Preferably, both the coupling device and the isolation device are wavelength division multiplexers.

[0023] Compared with the prior art, this application has the following beneficial effects:

[0024] The present application proposes a passive optical network physical link monitoring system, which is provided with a pulse transmitting device, a coupling device and a detection device. The pulse transmitting device transmits optical pulses of different wavelengths, and the wavelengths of the optical pulses correspond to n optical network units respectively. The optical pulses are coupled to the optical distribution network through the coupling device. The detection device obtains the corresponding information of the power and distance of the optical pulses in the trunk link and each branch optical fiber link, and can know the situation at each position on the trunk link and each branch optical fiber link. The present application uses optical pulses of different wavelengths as monitoring signals to monitor the situation of each optical fiber link and the trunk link respectively, which can perceive the potential threats of the physical link in advance and issue early warnings. After encountering sudden accidents, the fault point can also be located in time, and the operation risk of a single ONU can be clarified, which is convenient for the daily maintenance and accident repair of the passive optical network link. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A first structural diagram of a passive optical network physical link monitoring system provided in an embodiment of the present application;

[0027] Figure 2 A second structural diagram of a passive optical network physical link monitoring system provided in an embodiment of the present application;

[0028] Figure 3 A third structural diagram of a passive optical network physical link monitoring system provided in an embodiment of the present application;

[0029] Figure 4 The present invention is a schematic diagram of the working process of a passive optical network physical link monitoring system in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0032] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0033] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, it is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0034] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0035] In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] PON has a huge application market and complex application scenarios. Whether from the perspective of quality or continuity, improving the reliability of PON has become increasingly important.

[0037] There is no unified, widely used solution for PON link monitoring system, and even in most areas, there is no effective line protection mechanism. Existing data monitoring technology mainly generates virtual network topology based on network elements by monitoring hosts, network device nodes, and embedded monitoring devices on the user end, and uses a system center manager and a series of network management protocols to collect communication network data status information, which cannot meet the state perception and fault location of optical fiber physical links.

[0038] The physical link structure of PON mainly includes the optical line terminal (OLT) at the central office, the optical network unit (ONU) at the terminal, and the optical distribution network (ODN). Among them, ODN consists of passive components such as optical splitters, and does not contain any electronic components or power supplies. In PON, the upstream transmission time is divided into several time slots, and each time slot corresponds to an ONU. In this way, in the upstream direction, the signals of all ONUs can be transmitted to the OLT through a wavelength channel. In the downstream direction, the OLT sends the signal to all ONUs at the same time, each ONU receives all the signals, and then only selects its own time slot signal.

[0039] See also Figure 1 , Figure 1 A first structural diagram of a passive optical network physical link monitoring system provided in an embodiment of the present application.

[0040] An embodiment of the present application provides a passive optical network physical link monitoring system, wherein the optical fiber link of the passive optical network physical link includes a first optical line terminal, an optical distribution network and n optical network units, the optical distribution network includes n first unequal splitters, n is an integer greater than or equal to 1, and the monitoring system may include: a pulse transmitting device, a coupling device and a detection device.

[0041] The pulse transmitting device, whose output end is connected to the output end of the first optical line terminal, is used to transmit optical pulses of different wavelengths, the wavelengths of the optical pulses respectively correspond to the optical network units, and the wavelengths of the optical pulses and the network communication signals of the optical network units do not overlap. The coupling device, connected to the output end of the optical pulse transmitting device, is used to couple the optical pulses into the optical distribution network. The detection device, whose receiving end is connected to the output end of the first optical line terminal, is used to obtain the corresponding information of the power and distance of the optical pulses in the trunk link and the branch optical fiber links corresponding to each optical network unit, and complete the monitoring of each branch optical fiber link.

[0042] In the present application, the pulse transmitting device emits optical pulses of different wavelengths as monitoring signals. In order not to affect the normal communication of the network, the wavelength of the optical pulse does not overlap with the wavelength of the network communication signal of each optical network unit. The wavelength of the optical pulse corresponds to each optical network unit, so that the present application can monitor the branch optical fiber link corresponding to each optical network unit. In addition, while the optical pulse monitors each optical network unit, it passes through the trunk link. Therefore, the present application can also monitor the trunk link.

[0043] The coupling device is used to couple the optical pulse into the optical distribution network, and then the detection device can obtain the corresponding information of the power and distance of the optical pulse in the trunk link and each branch optical fiber link, so as to know whether the trunk link and each branch optical fiber link have faults or hidden dangers, and determine the location information of the fault or hidden danger in combination with the distance information.

[0044] The present application proposes a passive optical network physical link monitoring system, which couples optical pulses and communication signals of different wavelengths to the same link. The optical pulses and communication signals used as monitoring signals do not interfere with each other, and can accurately monitor the location and extent of failures or hidden dangers. The monitoring system of the present application can be applied to various passive optical network physical links, has strong versatility, and is easy to implement.

[0045] See also Figure 2 , Figure 2 It is a structural schematic diagram of a source optical network physical link and a passive optical network physical link monitoring system according to an embodiment of the present application.

[0046] A passive optical network physical link monitoring system is provided in an embodiment of the present application. Taking a power PON system as an example, a passive optical network physical link adopts a bidirectional hand-in-hand protection structure as an example, and a backup optical fiber link is provided. The backup optical fiber link includes a second optical line terminal and n second unequal splitters, and may also include a pulse transmitting device, a coupling device, a detection device, n first wavelength division multiplexers, n second wavelength division multiplexers and an isolation device. Figure 2In the figure, OLT 2 represents the second optical line terminal, Splitter 1' to Splitter n' represent the second unequal splitter, OLT 1 ​​represents the first optical line terminal, Splitter 1 to Splitter n represent n first unequal splitters, WDM 1 to WDM n represent n first wavelength division multiplexers, WDM 1' to WDM n' represent n first wavelength division multiplexers, and WDM 0' represents an isolation device. OLT 1 ​​and OLT 2 are located at both ends of the optical cable of the distribution network, and are connected to dual-port ONU 1 to ONU n and two OLTs by unequal splitters Splitter 1 to Splitter n and Splitter 1' to Splittern', respectively, to form a bidirectional hand-in-hand protection.

[0047] The input ends of the n first wavelength division multiplexers are respectively connected to the output ends of the n first unequal optical splitters, and the input ends of the n second wavelength division multiplexers are respectively connected to the output ends of the n second unequal optical splitters. One output end of the n first wavelength division multiplexers and the n second wavelength division multiplexers are respectively connected to n optical network units, and the other output ends of the n first wavelength division multiplexers are respectively connected to the other ends of the n second wavelength division multiplexers. The allowed passing wavelengths of each first wavelength division multiplexer correspond to the optical pulses emitted by the pulse emission device, and the allowed passing wavelengths of the first wavelength division multiplexers and the second wavelength division multiplexers connected to the same optical network unit are the same.

[0048] The present application can allocate a special "monitoring signal wavelength" to each optical network unit, and form a monitoring bypass through the first wavelength division multiplexer and the second wavelength division multiplexer of the corresponding wavelength. The optical network unit bridges of each branch optical fiber link, so that the monitoring signal can bypass the optical network unit to reach the backup optical fiber link, so that the complete dual-home protection optical fiber link is in the monitoring state.

[0049] In some embodiments of the present application, an isolation device may be further deployed on the second optical line terminal side, and the isolation device is connected between the second optical line terminal and the first second unequal splitter. For the bidirectional hand-in-hand protection structure, the monitoring signal input can be avoided on the second optical line terminal side. The specific structure of the isolation device can be selected according to actual needs, and this application does not limit it.

[0050] In other embodiments of the present application, both the coupling device and the isolation device may adopt a wavelength division multiplexer to facilitate design and application.

[0051] See also Figure 3 , Figure 3 It is a structural schematic diagram of a source optical network physical link and a passive optical network physical link monitoring system according to an embodiment of the present application.

[0052] A passive optical network physical link monitoring system is provided in an embodiment of the present application. Taking a power PON system as an example, a passive optical network physical link adopts a bidirectional hand-in-hand protection structure as an example, and a backup optical fiber link is provided. The backup optical fiber link includes a second optical line terminal and n second unequal splitters, and may also include a pulse transmitting device, a coupling device, a detection device, n first wavelength division multiplexers, n second wavelength division multiplexers and an isolation device.

[0053] In practical applications, the pulse emitting device only needs to be able to emit light pulses of different wavelengths, and the detection device only needs to be able to obtain the corresponding information of the power and distance of the light pulses in the link. The specific type and structure of the device can be selected according to needs, and this application does not impose any restrictions.

[0054] In some embodiments of the present application, the detection device can use OTDR (Optical Time Domain Reflectometry). Further preferably, the detection device can be integrated with the pulse emission device, and T-OTDR (Tunable OTDR, tunable wavelength optical time domain reflectometer) can be used. T-OTDR can measure the characteristics of optical fibers of different wavelengths by changing the wavelength of the emitted light pulse, and can be used for the analysis and testing of multi-wavelength optical fiber networks, as well as for more complex measurements and applications in the field of optical fiber communication and sensing. The backscattering generated by Rayleigh scattering and Fresnel reflection when light is transmitted in the optical fiber is used to understand the uniformity, defects, fractures, joint coupling and other properties of the optical fiber. When the light pulse encounters cracks, breakpoints, joints, bends and the like during the propagation of the optical fiber, the light pulse will produce a sudden reflection or attenuation, and the information of these reflections or attenuations is captured by the OTDR and used to analyze the characteristics of the optical fiber. The Rayleigh scattering power obtained by the OTDR is an exponentially decaying curve, which shows the loss along the optical fiber. By measuring the backscattering and reflection information in the optical fiber, the OTDR can obtain the power and distance information of the optical fiber. The T-OTDR device detects the ONU link individually by changing different wavelengths, generating a "power-distance" curve corresponding to the trunk link and each branch optical fiber link, thereby obtaining the fault and loss information of each optical fiber link. It also solves the basic problems encountered by ordinary OTDR in point-to-multipoint network monitoring, and can identify different branch users and accurately locate faults. T-OTDR is deployed on the OLT 1 ​​side, and its optical pulse is a wavelength-tunable laser source. T-OTDR is coupled into the optical distribution network ODN through WDM 0.

[0055] The wavelength of the optical pulse does not overlap with the network communication signal of each optical network unit. As an example, the optical pulse emitted by the T-OTDR can be in the U band or L band, and the OTDR is used to carry out link monitoring and assist in operation and maintenance. At the same time, the wavelength of the communication signal is in the C band.

[0056] As an example, in a 35kV and above distribution network, OLT 1, OLT 2 and T-OTDR are deployed in a 110kV substation, and ONU is deployed in a medium and high voltage distribution network substation, a distribution room, and a switch, forming a hand-in-hand protection structure. The monitoring system of this application can realize a large-scale physical link monitoring of the distribution network passive optical network. In another example, in a medium and low voltage distribution network where optical cables are partially deployed, OLT 1, OLT 2 and T-OTDR are deployed in a 35kV substation, and ONU is deployed in a ring network cabinet, a switch, a 10kV transformer, a distribution room and an electric vehicle charging station, forming a hand-in-hand protection structure. The monitoring system of this application can realize a large-scale physical link monitoring of the distribution network passive optical network.

[0057] This application adopts a chain topology in the distribution network and configures corresponding network protection, which is suitable for passive optical network physical link monitoring in various fields. It is advisable to adopt a fiber protection switching mechanism in the power PON system, and lay the fiber link topology according to the dual-belonging protection. The OLT and PON interfaces of the fiber link and the backup fiber link are in working condition. The OLT should ensure that the service information of the main PON interface can be synchronously backed up to the backup PON interface, so that during the protection switching process, the backup PON interface can maintain the service attributes of the ONU unchanged. Both ONU and OLT detect the link status and decide whether to switch based on the link status.

[0058] See also Figure 4 , Figure 4 A schematic diagram of a work flow of a passive optical network physical link monitoring system for this application may include the following steps:

[0059] S101, obtaining corresponding information of power and distance of optical pulses in a trunk link and each branch optical fiber link.

[0060] In practical applications, optical pulses of different wavelengths can be emitted. Since the monitoring signal wavelength of each ONU is different, the trunk link and each branch optical fiber link can be detected separately to obtain the corresponding information of power and distance. If T-OTDR is used, optical pulses of different wavelengths can be emitted, and the corresponding information of power and distance can be obtained. By obtaining the scattering information and reflection information of the optical pulses in the trunk link and each branch optical fiber link, the corresponding information of power and distance of the optical pulses in each trunk link and each branch optical fiber link can be obtained.

[0061] S102: Draw a power-distance curve of the optical pulse according to the power-distance correspondence information.

[0062] S103, determining the faults and losses of the trunk link and each branch optical fiber link, and the locations where the faults and losses occur, based on the power-distance curve of the optical pulse.

[0063] In actual applications, warning information can be issued when faults and losses occur, and different warning information can be issued according to the type and location of the faults and losses.

[0064] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0065] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0066] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0067] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A passive optical network physical link monitoring system, wherein the optical fiber link of the passive optical network physical link comprises a first optical line terminal, an optical distribution network and n optical network units, wherein the optical distribution network comprises n first unequal optical splitters, where n is an integer greater than or equal to 1; characterized in that: include: A pulse transmitting device, the output end of which is connected to the output end of the first optical line terminal, and is used to transmit optical pulses of different wavelengths, the wavelengths of the optical pulses respectively corresponding to the optical network units, and the wavelengths of the optical pulses and the network communication signals of the optical network units do not overlap; A coupling device, connected to the output end of the optical pulse transmitting device, for coupling the optical pulse into the optical distribution network; The detection device, whose receiving end is connected to the output end of the first optical line terminal, is used to obtain the power and distance corresponding information of the optical pulses in the trunk link and the branch optical fiber links corresponding to each optical network unit, and complete the monitoring of each branch optical fiber link.

2. The passive optical network physical link monitoring system according to claim 1, characterized in that: Also includes n first wavelength division multiplexers and n second wavelength division multiplexers; The passive optical network physical link adopts a bidirectional hand-in-hand protection structure, and the backup optical fiber link includes a second optical line terminal and n second unequal splitters; The input ends of the n first wavelength division multiplexers are respectively connected to the output ends of the n first unequal optical splitters, and the input ends of the n second wavelength division multiplexers are respectively connected to the output ends of the n second unequal optical splitters; One output end of n first wavelength division multiplexers and n second wavelength division multiplexers are respectively connected to n optical network units, and the other output ends of the n first wavelength division multiplexers are respectively connected to the other ends of n second wavelength division multiplexers. The allowed passing wavelength of each first wavelength division multiplexer corresponds to the optical pulse emitted by the pulse emitting device, and the allowed passing wavelength of the first wavelength division multiplexer and the second wavelength division multiplexer connected to the same optical network unit is the same.

3. The passive optical network physical link monitoring system according to claim 2, characterized in that: Also includes isolation devices; The isolation device is connected between the second optical line terminal and the first second unequal optical splitter.

4. The passive optical network physical link monitoring system according to claim 3, characterized in that: The detection device adopts OTDR.

5. The passive optical network physical link monitoring system according to claim 4, characterized in that: The pulse transmitting device and the detecting device jointly adopt T-OTDR.

6. The passive optical network physical link monitoring system according to claim 5, characterized in that: The coupling device and the isolation device both adopt wavelength division multiplexers.

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