CN112583475B

CN112583475B - Test method, optical line terminal and optical network terminal

Info

Publication number: CN112583475B
Application number: CN201910927733.2A
Authority: CN
Inventors: 杨素林
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-09-27
Filing date: 2019-09-27
Publication date: 2022-08-19
Anticipated expiration: 2039-09-27
Also published as: CN112583475A

Abstract

The application discloses a test method, which comprises the following steps: the optical line terminal OLT sends a test instruction to N optical network units ONU integrated with an OTDR, the test instruction is used for indicating the N ONUs to send test signals of the OTDR in a first test time window, the test signals sent by the N ONUs synchronously reach the same optical splitter, and N is a positive integer greater than 1. According to the technical scheme provided by the application, the OLT can control the ONTs to start the OTDR test through the test instruction, and the ONTs can send the OTDR test signal according to different equivalent delay delays in the first test time window, so that the plurality of OTDR test signals can synchronously reach the same optical splitter, the strength of the test signal passing through the optical splitter is enhanced, and the OTDR detection capability is improved.

Description

Test method, optical line terminal and optical network terminal

Technical Field

The application relates to the technical field of communication, in particular to a test method.

Background

With the increasing abundance of telecommunication services, users have an increasing demand for access bandwidth. Among various access technologies, operators of various countries around the world have a great bandwidth and are suitable for long-distance transmission, and Fiber To The Home (FTTH) is a inevitable choice for access networks. In the specific implementation of FTTH, Passive Optical Network (PON) technology is currently adopted more. The PON refers to a point-to-multipoint (P2 MP) fiber access technology, and the PON system is composed of an Optical Line Terminal (OLT) on a local side, an Optical Network Unit (ONU) or an Optical Network Terminal (ONT) on a user side, and an Optical Distribution Network (ODN).

In order to ensure the normal operation of each service in the PON and improve the stability of the network service, it is necessary to monitor the status of each link in the PON on-line, predict various conditions that may occur in the optical link at any time, and take corresponding measures to ensure the reliability of the network service quality. Conventionally, for monitoring and maintaining an optical fiber link, an optical time-domain reflectometer (OTDR) is generally used. The characteristic attribute of a single optical fiber or a complete link can be evaluated through the OTDR, and ideal equipment for monitoring a traditional optical fiber network by loss faults and inter-event distances can be seen clearly through a measurement curve of the OTDR.

However, when the OTDR is applied to the PON system, the large loss introduced by the optical splitter reduces the testing capability of the OTDR, so that the test signal emitted by the OTDR hardly penetrates through the optical splitter to detect an event on the optical fiber in front of the optical splitter (near OLT side). Therefore, how to improve the detection capability of OTDR needs to be solved urgently.

Disclosure of Invention

The embodiment of the application provides a test method, which improves OTDR detection performance.

In order to achieve the above purpose, the embodiments of the present application provide the following technical solutions:

a first aspect of the present application provides a testing method, which may be applied to a PON network, and may include: the optical line terminal OLT sends a test instruction to N optical network units ONU integrated with an OTDR, the test instruction is used for indicating the N ONUs to send test signals of the OTDR in a first test time window, the test signals sent by the N ONUs synchronously reach the same optical splitter, and N is a positive integer greater than 1. It can be known from the first aspect that the OLT may control a plurality of ONTs to start a test of the OTDR at a time, and the ONTs may send the test signal of the OTDR according to different equivalent delay delays within a first test time window, so that the test signals of the OTDR may synchronously reach the same optical splitter (for example, synchronously reach a common port of the optical splitter), the strength of the test signal passing through the optical splitter is enhanced, and the detection capability of the OTDR is improved.

Optionally, with reference to the first aspect, in a first possible implementation manner, the test instruction is specifically configured to instruct the N ONUs to send the OTDR test signal within the first test time window according to the equivalent time delay eqd, and eqd is configured to ensure that the test signals sent by the N ONUs arrive at the same optical splitter synchronously.

Optionally, with reference to the first possible implementation manner of the first aspect, in a second possible implementation manner, eqd is sent to the N ONUs through a test instruction.

Optionally, with reference to the first aspect, the first possible implementation manner of the first aspect, and the second possible implementation manner of the first aspect, in a third possible implementation manner, the method may further include: the OLT receives OTDR test data sent by the N ONUs; the OLT segments the received test data according to the position of the M-level optical splitter, wherein M is a positive integer; the OLT determines an average value of first-stage data, wherein the first-stage data is data between any one-stage optical splitter in the M-stage optical splitters and the OLT or data between any two-stage optical splitters in the M-stage optical splitters. It can be known from the third possible manner of the first aspect that the random noise in the OTDR test process is eliminated by averaging the test number, a waveform with a higher signal-to-noise ratio is obtained, and the detection performance of the OTDR can be further improved.

Optionally, with reference to the first aspect and the first to third possible implementation manners of the first aspect, in a fourth possible implementation manner, the sending, by the OLT, a test instruction to N optical network units ONU integrated with an optical time domain reflectometer OTDR may include: the OLT sends a test instruction to the ONU through a first message, wherein the first message is any one of a DBA message, an operation administration maintenance OAM message, a bandwidth mapping BWMAP message, an optical network terminal management and control interface OMCI message and a physical layer operation administration maintenance PLOAM message.

Optionally, with reference to the first aspect and the first to fourth possible implementation manners of the first aspect, in a fifth possible implementation manner, the method may further include: the OLT determines that an optical device used for receiving and transmitting data of a target ONU connected with the OLT is the same as an optical device used for receiving and transmitting signals of an OTDR integrated on the ONU; and if the target ONU does not participate in the OTDR test, the OLT instructs the target ONU to close the optical device for receiving and transmitting data. As can be seen from the fifth possible manner of the first aspect, the ONU that does not participate in the OTDR test does not send data during the test, which is beneficial to improving the accuracy of the test data.

Optionally, with reference to the first aspect and the first to fifth possible implementation manners of the first aspect, in a sixth possible implementation manner, the method may further include: and the OLT instructs at least two ONUs to report the test data after waiting for at least a first time length, wherein the first time length is not less than a first test time window.

A second aspect of the present application provides a testing method, which may include: an optical network unit ONU receives a test instruction sent by an optical line terminal OLT, an optical time domain reflectometer OTDR is integrated on the ONU, and the test instruction instructs the ONU to start an OTDR test in a first test time window; the ONU transmits the OTDR test signal within the first test window according to the equivalent time delay eqd.

Optionally, with reference to the second aspect, in a first possible implementation manner, the method may further include: the ONU determines M moments according to the position of the M-level optical splitter, wherein M is a positive integer; starting timing when the ONU sends a test signal; and when the timing time reaches the time corresponding to the M times, increasing the gain of the TIA of the transimpedance amplifier of the ONU.

Optionally, with reference to the second aspect or the first possible implementation manner of the second aspect, in a second possible implementation manner, the method may further include: and when the timing time reaches the time corresponding to the M times, increasing the gain of the photoelectric detector PD of the ONU.

A third aspect of the present application provides a passive optical network system, which may include: an optical line terminal OLT and N optical network units ONU, where the OLT is connected to the N ONTs in a point-to-multipoint manner through an M-stage optical splitter, N is a positive integer, M is a positive integer, the OLT is the OLT described in the first aspect or any one of the possible implementations of the first aspect, the ONU is the ONU described in the second aspect or any one of the possible implementations of the second aspect, and the M-stage optical splitter is configured to distribute data sent by the OLT to the N ONUs and concentrate data sent by the N ONUs to the OLT.

Optionally, with reference to the third aspect, in a first possible implementation manner, the test signals sent by the N ONUs arrive at any optical splitter of the M-class optical splitters in synchronization.

A fourth aspect of the present application provides an optical line terminal OLT, which may include: the receiving and sending unit is used for sending a test instruction to N Optical Network Units (ONU) integrated with an Optical Time Domain Reflectometer (OTDR), the test instruction is used for indicating the N ONUs to send test signals of the OTDR in a first test time window, the test signals sent by the N ONUs synchronously reach the same optical splitter, and N is a positive integer greater than 1.

Optionally, with reference to the fourth aspect, in a first possible implementation manner, the test instruction is specifically configured to instruct the N ONUs to send the OTDR test signal within the first test time window according to the equivalent time delay eqd, and eqd is configured to ensure that the test signals sent by the N ONUs arrive at the same optical splitter synchronously.

Optionally, with reference to the first possible implementation manner of the fourth aspect, in a second possible implementation manner, eqd is sent to the N ONUs through a test instruction.

Optionally, with reference to the fourth aspect, the first kind of the fourth aspect, and the second possible implementation manner of the fourth aspect, in a third possible implementation manner, the transceiver unit is further configured to receive OTDR test data sent by the N ONUs; the OLT may further include: the processing unit is used for segmenting the test data received by the transceiving unit according to the position of the M-level optical splitter, wherein M is a positive integer; and the processing unit is further configured to determine an average value of first segment data, where the first segment data is data between any one of the M-stage optical splitters and the OLT or data between any two of the M-stage optical splitters.

Optionally, with reference to the fourth aspect and the third possible implementation manner of the first to fourth aspects, in a fourth possible implementation manner, the transceiver unit is specifically configured to send a test instruction to the ONU through a first message, where the first message is any one of a dynamic bandwidth allocation DBA message, an operation, management and maintenance OAM message, a bandwidth mapping BWMAP message, an optical network terminal management and control interface OMCI message, and a physical layer operation, management and maintenance PLOAM message.

Optionally, with reference to the fourth aspect and the fourth possible implementation manners of the first to fourth aspects, in a fifth possible implementation manner, the processing unit is further configured to determine that an optical device, which is connected to the OLT and used by the target ONU for transceiving data, is the same as an optical device, which is integrated on the ONU and used by an OTDR for transceiving signals; and the transceiving unit is also used for instructing the target ONU to close the optical device for transceiving data by the OLT if the target ONU determined by the processing unit does not participate in the OTDR test.

Optionally, with reference to the fourth aspect and the fifth possible implementation manner of the first to fourth aspects of the fourth aspect, in a sixth possible implementation manner, the transceiver unit is further configured to instruct at least two ONUs to report the test data after waiting for at least a first time duration, where the first time duration is not less than the first test time window.

A fifth aspect of the present application provides an optical network unit ONU, which may include: the optical network unit comprises a receiving and sending unit, a first test time window and a second test time window, wherein the receiving and sending unit is used for receiving a test instruction sent by an optical line terminal OLT, an optical time domain reflectometer OTDR is integrated on the ONU, and the test instruction instructs the ONU to start an OTDR test in the first test time window; and the transceiving unit is further used for sending the test signal of the OTDR in the first test window according to the equivalent time delay eqd.

Optionally, with reference to the fifth aspect, in a first possible implementation manner, the method may further include: the processing unit is used for determining M moments according to the positions of the M-level optical splitters, wherein M is a positive integer; the receiving and transmitting unit is used for transmitting a test signal; the processing unit is also used for starting timing when the transceiving unit sends the test signal; and the processing unit is further used for increasing the gain of the TIA of the transimpedance amplifier of the ONU when the timing time reaches the time corresponding to the M times.

Optionally, with reference to the fifth aspect or the first possible implementation manner of the fifth aspect, in a second possible implementation manner, the processing unit is further configured to increase a gain of the photodetector PD of the ONU when the timing time reaches a time corresponding to the M times.

A sixth aspect of the present application provides an optical line terminal OLT, which may include: the optical network unit comprises a communication interface, a first Optical Time Domain Reflectometer (OTDR) and N Optical Network Units (ONUs) integrated with the OTDR, wherein the communication interface is used for sending a test instruction to the N Optical Network Units (ONUs) integrated with the OTDR, the test instruction is used for indicating the N ONUs to send a test signal of the OTDR in a first test time window, the test signal sent by the N ONUs synchronously reaches the same optical splitter, and N is a positive integer greater than 1.

Optionally, with reference to the sixth aspect, in a first possible implementation manner, the test instruction is specifically configured to instruct the N ONUs to send the OTDR test signal within the first test time window according to the equivalent time delay eqd, and eqd is configured to ensure that the test signals sent by the N ONUs arrive at the same optical splitter synchronously.

Optionally, with reference to the first possible implementation manner of the sixth aspect, in a second possible implementation manner, eqd is sent to the N ONUs through a test instruction.

Optionally, with reference to the sixth aspect, the first possible implementation manner of the sixth aspect, and the second possible implementation manner of the sixth aspect, in a third possible implementation manner, the communication interface is further configured to receive OTDR test data sent by N ONUs; the OLT may further comprise a memory for storing computer-readable instructions; further comprising a processor coupled to the memory, the processor configured to: segmenting test data received by a communication interface according to the position of an M-level optical splitter, wherein M is a positive integer; and the processor is further used for determining an average value of first-segment data, wherein the first-segment data is data between any one-stage optical splitter in the M-stage optical splitters and the OLT or data between any two-stage optical splitters in the M-stage optical splitters.

Optionally, with reference to the sixth aspect and the third possible implementation manner of the first to sixth aspects, in a fourth possible implementation manner, the communication interface is specifically configured to send a test instruction to the ONU through a first message, where the first message is any one of a dynamic bandwidth allocation DBA message, an operation, management and maintenance OAM message, a bandwidth mapping BWMAP message, an optical network terminal management and control interface OMCI message, and a physical layer operation, management and maintenance PLOAM message.

Optionally, with reference to the sixth aspect and the fourth possible implementation manner of the first to sixth aspects, in a fifth possible implementation manner, the processor is further configured to determine that an optical device, which is connected to the OLT and used by the target ONU for transceiving data, is the same as an optical device, which is integrated on the ONU and used by an OTDR for transceiving signals; and the communication interface is further used for indicating the target ONU to close an optical device for receiving and transmitting data by the OLT if the target ONU determined by the processor does not participate in the OTDR test.

Optionally, with reference to the sixth aspect and the fifth possible implementation manner of the first to sixth aspects, in a sixth possible implementation manner, the communication interface is further configured to instruct the at least two ONUs to report the test data at least after waiting for a first duration, where the first duration is not less than the first test time window.

A seventh aspect of the present application provides an optical network unit ONU, which may include: the optical line terminal OLT comprises a communication interface, an Optical Time Domain Reflectometer (OTDR) and a first test time window, wherein the communication interface is used for receiving a test instruction sent by the optical line terminal OLT, the ONU is integrated with the OTDR, and the test instruction instructs the ONU to start the test of the OTDR in the first test time window; and the communication interface is further used for sending the test signal of the OTDR in the first test window according to the equivalent time delay eqd.

Optionally, with reference to the seventh aspect, in a first possible implementation manner, the method may further include: a memory for storing computer readable storage instructions and a processor coupled to the memory for determining M times based on the M-stage splitter position, M being a positive integer; a communication interface for transmitting a test signal; the processor is also used for starting timing when the communication interface sends the test signal; and the processor is further used for increasing the gain of the TIA of the transimpedance amplifier of the ONU when the timing time reaches the time corresponding to the M times.

Optionally, with reference to the seventh aspect or the first possible implementation manner of the seventh aspect, in a second possible implementation manner, the processor is further configured to increase a gain of the photodetector PD of the ONU when the timing time reaches a time corresponding to the M times.

An eighth aspect of the present application provides a computer-readable storage medium, which stores instructions that, when executed on a computer, enable the computer to perform the method for testing of the first aspect or any one of the possible implementations of the first aspect.

A ninth aspect of the present application provides a computer-readable storage medium having stored therein instructions, which, when run on a computer, cause the computer to perform the method of testing of the second aspect or any one of the possible implementations of the second aspect.

A tenth aspect of the present application provides a computer program product comprising instructions which, when run on a computer, enable the computer to perform the method of testing of the first aspect or any one of the possible implementations of the first aspect.

An eleventh aspect of the present application provides a computer program product comprising instructions that, when run on a computer, cause the computer to perform the method of testing of the second aspect or any one of the possible implementations of the second aspect.

According to the technical scheme provided by the application, the OLT can control the ONTs to start the OTDR test at one time, and the ONTs can send the OTDR test signal according to different equivalent delay delays in a first test time window, so that the OTDR test signals can synchronously reach the same optical splitter (for example, synchronously reach a common port of the optical splitter), the strength of the test signal passing through the optical splitter is enhanced, and the OTDR detection capability is improved.

Drawings

FIG. 1 is a schematic diagram of a PON system;

fig. 2 is a schematic flowchart of a testing method according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of another PON system;

FIG. 4 is a schematic flow chart of another testing method provided in the embodiments of the present application;

FIG. 5 is a schematic flow chart of another testing method provided in the embodiments of the present application;

FIG. 6 is a schematic flow chart of another testing method provided in the embodiments of the present application;

fig. 7 is a schematic structural diagram of an ONU;

fig. 8 is a schematic diagram of another ONU;

FIG. 9 is a schematic flowchart of another testing method provided in the embodiments of the present application;

FIG. 10 is a schematic flow chart of another testing method provided in the embodiments of the present application;

fig. 11 is a schematic hardware structure diagram of an OLT according to an embodiment of the present application;

fig. 12 is a schematic structural diagram of an OLT according to an embodiment of the present application;

fig. 13 is a schematic diagram of a hardware structure of an ONU according to an embodiment of the present application;

fig. 14 is a schematic structural diagram of an ONU provided in the embodiment of the present application.

Detailed Description

Embodiments of the present application will be described with reference to the accompanying drawings, and it is to be understood that the described embodiments are only some embodiments of the present application, and not all embodiments of the present application. As can be known to those skilled in the art, with the development of technology and the emergence of new scenarios, the technical solution provided in the embodiments of the present application is also applicable to similar technical problems.

An embodiment of the present application provides a testing method, where an OLT enables OTDR synchronization testing on one or more ONUs, that is, a test signal of an OTDR on multiple ONUs is sent to a synchronization arrival optical splitter (for example, a common port of the synchronization arrival optical splitter), so as to improve detection capability of the OTDR, which is described in detail below.

The terms "first," "second," and the like in the description and in the claims of the present application and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be practiced otherwise than as specifically illustrated or described herein. Moreover, the terms "comprises," "comprising," and any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or modules is not necessarily limited to those steps or modules explicitly listed, but may include other steps or modules not expressly listed or inherent to such process, method, article, or apparatus. The naming or numbering of the steps appearing in the present application does not mean that the steps in the method flow have to be executed in the chronological/logical order indicated by the naming or numbering, and the named or numbered process steps may be executed in a modified order depending on the technical purpose to be achieved, as long as the same or similar technical effects are achieved. The division of the modules presented in this application is a logical division, and in practical applications, there may be another division, for example, multiple modules may be combined or integrated into another system, or some features may be omitted, or not executed, and in addition, the shown or discussed coupling or direct coupling or communication connection between each other may be through some ports, and the indirect coupling or communication connection between the modules may be in an electrical or other similar form, which is not limited in this application. Moreover, the modules or sub-modules described as separate components may or may not be physically separated, may or may not be physical modules, or may be distributed in a plurality of circuit modules, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present application.

It should be noted that, in the embodiments of the present application, the terms "network" and "system" are often used interchangeably, but those skilled in the art can understand the meaning of the terms. Information (information), signal (signal), message (message) may sometimes be mixed, it being noted that the intended meaning is consistent when no distinction is emphasized.

It should be noted that, in the embodiments of the present application, "reporting" and "feedback" are often used interchangeably, but those skilled in the art can understand the meaning of the "reporting" and the "feedback" as well as the "response". Therefore, in the embodiments of the present application, the intended meaning thereof is consistent when the distinction thereof is not emphasized.

For better understanding, before introducing the embodiments of the present solution, a Passive Optical Network (PON) and an optical time-domain reflectometer (OTDR) are introduced.

In general, a PON technology refers to a point-to-multipoint (P2 MP) fiber access technology, and a PON system includes an Optical Line Termination (OLT) on a local side, an Optical Network Unit (ONU) or an Optical Network Termination (ONT) on a user side, and an Optical Distribution Network (ODN). The OLT is connected with network side equipment (such as a switch, a router and the like) at an upper layer, and the lower layer is connected with one or more ODNs. The ONU provides a user-side interface for an Optical Access Network (OAN) while being connected to the ODN. An ONU is called an Optical Network Terminal (ONT) if the ONU provides a user port function at the same time, such as an Ethernet user port or a Plain Old Telephone Service (POTS) user port. It should be noted that, as mentioned in this application, unless otherwise specified, the ONU includes the ONU and the ONT. An ODN is a passive optical splitter, generally including a passive optical splitter (also called splitter), a trunk fiber, and a branch fiber. A passive optical splitter, also referred to as an optical splitter, functions to distribute downstream data and to concentrate upstream data. The optical splitter is provided with an uplink optical interface and a plurality of downlink optical interfaces. The optical signals from the upstream optical interfaces are distributed to all downstream optical interfaces for transmission, and the optical signals from the downstream optical interfaces are distributed to only one upstream optical interface for transmission. The ODN may collectively transmit the upstream data of the plurality of ONUs to the OLT, and may also transmit the downstream data of the OLT to each ONU. In the PON system, transmission in the direction from the OLT to the ONUs is called downstream transmission, and conversely, upstream transmission is uplink transmission in which the OLT broadcasts downstream data to the ONUs, the upstream transmission uses time division multiplexing, and each ONU transmits upstream data to the OLT in accordance with a transmission time slot allocated by the OLT.

The PON system mainly adopts a tree topology structure, as shown in fig. 1, which is a schematic diagram of the PON system. The OLT provides a network side interface for the PON system, and is connected to one or more ODNs, as shown in fig. 1, where the ODNs are connected to connect the OLT device and the ONU device, and are used to distribute or multiplex data signals between the OLT and the ONU. The ONU provides a user side interface for the PON system. In fig. 1, a first-stage splitter structure is shown, where the front side of the splitter (near OLT side) is referred to as a trunk fiber, and the rear side of the splitter (near ONT side) is referred to as a branch fiber. If the second-stage optical splitter structure, namely the ODN network, comprises 1 first-stage optical splitter, a plurality of second-stage optical splitters, a trunk, distribution optical fibers and branch optical fibers, wherein the distribution optical fibers are optical fibers between the first-stage optical splitter and the second-stage optical splitters.

The PON includes various types, such as an asynchronous transfer mode PON (APON), a Broadband PON (BPON), an Ethernet PON (EPON), a Gigabit PON (GPON), a 10 gigabit ethernet PON (10G ethernet passive PON, 10G-EPON), etc., where the GPON, the EPON, and the 10 gigabit ethernet PON are mainstream PONs, and this embodiment does not limit the types of the PONs, and the PON/EPON is exemplified for uplink and downlink transmission by taking the mainstream PON as an example, the GPON/EPON adopts 1490nm and the 10G PON adopts 1577nm, and the OLT broadcasts downlink data streams to all ONUs in a Time Division Multiplexing (TDM) manner, and each ONU receives only data with an identifier. As shown in fig. 1, the OLT broadcasts downstream data 1, downstream data 2, and downstream data 3 to all ONUs, each ONU receives only data with its own identifier, and discards other data, for example, a first ONU receives only downstream data 1, discards downstream data 2 and downstream data 3, a second ONU receives only downstream data 2, discards downstream data 1 and downstream data 3, and a third ONU receives only downstream data 3, and discards downstream data 1 and downstream data 2. On the contrary, the wavelength from ONU to OLT is uplink, the wavelength of 1310nm is adopted by GPON/EPON, and the wavelength of 1270nm is adopted by 10G PON. Because each ONU shares the ODN and the OLT, in order to ensure that uplink data of each ONU does not collide, the PON system uses a time-division multiple access (TDMA) method, that is, a time slot is allocated to each ONU by the OLT, and each ONU must strictly transmit data according to the time slot allocated by the OLT.

In order to ensure the normal operation of each service in the PON and improve the stability of the network service, it is necessary to monitor the status of each link in the PON on-line, predict various conditions that may occur in the optical link at any time, and take corresponding measures to ensure the reliability of the network service quality. Conventionally, for monitoring and maintaining an optical fiber link, an optical time-domain reflectometer (OTDR) is generally used. The characteristic attributes of a single optical fiber or a complete link can be evaluated through the OTDR, and ideal equipment for monitoring a traditional optical fiber network by loss faults and inter-event distances can be seen clearly through the measurement curve of the OTDR. Optical time domain reflectometry is derived from time domain reflectometry (radar) and is a generalization of electrical time domain reflectometry in the optical frequency range. The laser of the OTDR emits a test signal into the optical fiber to be tested, when the test signal is transmitted through the optical fiber, a backscattering signal (including rayleigh scattering caused by microscopic unevenness of the refractive index of the optical fiber and fresnel reflection caused by discontinuity of the refractive index) or an event of the optical fiber link (the event refers to a defect caused by welding, connector, bending, breaking, etc. in the optical fiber link, and other changes that may cause optical transmission characteristics such as water seepage) is formed into a reflection signal, the detector of the OTDR detects the strength and arrival time of the backscattering signal or the reflection signal, and calculates and obtains the line attenuation condition distributed along the length of the optical fiber and an event curve on the line. The event type and location on the fiber line can be accurately located by OTDR.

However, when the OTDR is applied to the PON system, the applicant has found that there is a problem that the large loss introduced by the optical splitter reduces the testing capability of the OTDR, so that the test signal emitted by the OTDR hardly penetrates through the optical splitter to detect an event on the optical fiber before the optical splitter (near OLT side). There is a way to enhance the strength of the transmitted signal of the OTDR or to improve the performance of the receiver, but this way is limited by the eye safety of the ONT, the strength of the transmitted signal cannot be increased infinitely, and in addition, the increase of the test signal strength, which increases the cost, is also an improvement of the performance of the receiver. In order to solve the technical problem, the application provides a testing method, which improves the detection capability of the OTDR.

Fig. 2 is a schematic flow chart of a testing method according to an embodiment of the present application.

As shown in fig. 2, a testing method may include the steps of:

201. and the OLT sends a test instruction to the N ONUs integrated with the OTDR.

The OLT sends a test instruction to the N ONUs integrated with the OTDR, wherein N is a positive integer greater than 1, namely the OLT sends the test instruction to at least two ONUs integrated with the OTDR.

The test instruction is used for instructing the N ONUs to start OTDR test in a first test time window, and test signals sent by the N ONUs synchronously reach the same optical splitter.

The first test time window is configured for the OLT, and within the first test window, one or more OTDR tests may be performed. The first test time window is related to the fiber link length between the OLT and the ONU. For example, if the length of the optical fiber between the OLT and the farthest ONU participating in the OTDR test is 20km, since the time required for 20km during which the optical signal is transmitted in a single-mode optical fiber in a single-direction is about 100us, the first test time window needs to consider the time for the farthest ONU to send the test signal to the OLT and then return to the ONU, and therefore the first test time window (sometimes referred to as a test quiet window, which is not limited by the name of the embodiment of the present application) for sending one test is at least about 200 us. In practical application, because a certain margin needs to be considered, the test window of one test, i.e. the first test time window, can be set as required.

Because the lengths of the branch optical fibers connected to each ONU may be different, to ensure that the test signals of multiple ONUs synchronously reach a certain identical optical splitter, the time when the ONUs send the test signals needs to be controlled. In order to ensure that the time when the test signals of a plurality of ONUs reach a certain optical splitter is the same, when the ONUs determine to start the OTDR test, the ONUs correspondingly delay different time when sending the test signals according to the difference between the distances from the optical splitters, and the sending delay time is called equivalent delay. In this embodiment of the present application, the equivalent delay may be carried in the test instruction, or may not be carried in the test instruction, and the ONU may determine the time for delaying the transmission according to the prestored equivalent delay. Illustratively, two methods of determining the equivalent delay are given below:

the first mode is as follows: the OLT first determines a signal transmission duration Tmax (time required for a test signal to pass from the OLT to the ONU or from the ONU to the OLT) of an ONU at the farthest distance from the OLT among ONUs supported by the OLT. And any value (hereinafter referred to as a first value) greater than or equal to Tmax is sent to the N ONUs, and the N ONUs determine the equivalent time delay according to the difference between the transmission duration and the received first value.

The second mode is as follows: assuming that the transmission time length of the test signal between each ONU supported by the OLT and the OLT (the time required for the test signal to pass from the OLT to the ONU or from the ONU to the OLT) is T1, T2, T3 … … Tn, N is a positive integer, assuming that the maximum transmission time length is Tm, Tm is max (T1, T2, T3 … … Tn), and m is an integer, the equivalent delay of each ONU may be Tm-Ti (i is 1,2,3, … … N), and the OLT may directly transmit the determined equivalent delay to the N ONUs.

It should be noted that the ONU may determine the time for sending the test signal according to the equivalent delay, the ONU may delay the equivalent delay to send the test signal within the first test time window, and the ONU may also delay the equivalent delay and a certain fixed delay to send the test signal within the first test time window.

The OLT may send the test instruction to the N ONUs in a broadcast manner, the OLT may also send the test instruction to the N ONUs in a multicast manner, and the OLT may also send the test instruction to the N ONUs in a unicast manner, where the test instruction may or may not carry the equivalent delay in the broadcast manner, the multicast manner, or the unicast manner, and this embodiment of the present application is not limited thereto.

202. The first ONU sends a first test signal of the first OTDR within a first test time window according to the first equivalent time delay.

The first ONU sends a first test signal of the first OTDR within a first test time window according to the first equivalent time delay eqd, the first test signal and a second test signal synchronously reach the same optical splitter, the second test signal is a second OTDR test signal sent by the second ONU within the first test window according to the second eqd, and the second ONU is an optical network unit that receives a test instruction sent by the OLT except the first ONU.

In a specific embodiment, the test instruction is configured to instruct the N ONUs to send OTDR test signals within a first test time window according to the equivalent delay eqd, and after receiving the test instruction, the first ONU sends the first test signal of the first OTDR within the first test time window according to the first equivalent delay. The first ONU may obtain the first equivalent delay through multiple ways, for example, the test instruction carries the equivalent delay, the first ONU may obtain the equivalent delay through the test instruction sent by the OLT, and determine the time to send the first test signal according to the received equivalent delay, and the first ONU may also determine the time to send the first test signal according to the prestored equivalent delay. For example, a GPON state machine may include 7 states: initial state, standby state, serial number state, ranging state, running state, POPUP state, and emergency stop state. In a ranging state, each ONU connected to the OLT obtains its own equalization delay, and when entering an OTDR test in an operating state, because each ONU connected to the OLT already stores its own equalization delay, in this embodiment of the present application, the equalization delay is an equivalent delay, and therefore the OLT does not need to send the equivalent delay to each ONU.

In a specific embodiment, the ONU may further determine, according to a predefined communication protocol between the ONU and the OLT, that after receiving a test instruction sent by the OLT, the ONU sends a first test signal of the first OTDR within a first test time window according to the first equivalent delay. That is to say, after receiving the test instruction by default, the ONU sends the first test signal of the first OTDR within the first test time window according to the first equivalent delay.

After receiving the test instruction, the first ONU adjusts a clock for sending the first test signal by the OTDR according to eqd, that is, when the OTDR prepares to send the first test signal, the first test signal is sent after a period of time corresponding to eqd of the first ONU needs to be delayed, so that the test signals of the multiple ONUs synchronously reach a certain same optical splitter.

As can be seen from the embodiment corresponding to fig. 2, the OLT enables the OTDR synchronous test on one or more ONUs, that is, the test signals of the OTDRs on the ONUs arrive at the optical splitter synchronously (for example, arrive at the common port of the optical splitter synchronously), and finally arrive at the OLT synchronously, so that the test signals passing through the optical splitter are enhanced, the echo signals before the optical splitter received by the OTDR receiver on each ONU are enhanced by about N times, where N is the number of ONUs sending the test signals under the optical splitter, and according to the dynamic range formula for equivalently increasing the signal power, the detection capability before the optical splitter (near the OLT side) is increased by about 5 × log ₁₀ NdB (neodymium iron boron). The following takes a scenario in which the ODN includes two stages of optical splitters as an example, and illustrates the test method provided in the embodiment of the present application.

Fig. 3 is a schematic diagram of a PON system. The PON system comprises an OLT, an ONU and an ODN. The ODN comprises a first-stage optical splitter and a second-stage optical splitter. ONU is integrated withThe OTDR function, ONU, is the ONU described in the embodiment corresponding to fig. 2. The OLT supports controlling a plurality of ONUs to start the OTDR test at the same time, that is, the OLT is the OLT described in the embodiment corresponding to fig. 2. The test signals sent by the multiple ONUs arrive at the optical splitter (which may be a branch port or a common port of the optical splitter) at the same time. For example, the test signals transmitted by ONU1, ONU2, and ONU3 shown in fig. 3 reach optical splitter 221 at the same time, and are superimposed together to obtain test signal 251, and the test signals transmitted by ONU4, ONU5, and ONU6 reach optical splitter 222 at the same time, and are superimposed together to obtain test signal 252. The superimposed test signal 251 and test signal 252 arrive at the splitter 111 at the same time and are superimposed to obtain a test signal 253. Assuming that the power of the test signal transmitted by each ONU reaches the splitter is the same, the test signal is equivalently increased by 3 times for ONU1, ONU2, and ONU3 after passing through the splitter 221, which is equivalent to the splitting ratio of the upstream splitter 221 being reduced by 3 times, according to the formula of the OTDR dynamic range (OTDR dynamic range 1/2 { Pin + [ Pb-10 log10 (W))]-Pn, where Pin is the input power of the test signal, in dBm, Pb is the rayleigh scattering intensity, wavelength dependent, 1310nm light is about-77 dB/nm, W is the test signal pulse width, in ns, Pn is the receiver equivalent noise intensity, the receiver equivalent noise intensity can be reduced by averaging and receiver performance), the test capability before a splitter at the end of the first stage near the OLT can be improved by 5 × log ₁₀ (3) (approximately 2.88 db). For each ONU, the equivalent splitting ratio is reduced

Multiple (the echo signal before the optical splitter 221 at the OLT end still needs to pass through the optical splitter, the attenuation of the optical splitter 221 to the echo signal remains unchanged, and the equivalent splitting ratio decreases in two directions

Multiple).

If the splitting ratio of the optical splitter 221 is 1 × 8 (i.e. the optical splitter has 1 trunk or common port, 8 branch ports, and 8 branch optical fibers can be connected to 8 ONUs at most), and 8 ONUs perform synchronous testing by using the testing method provided by the present application, then a forward test signal before (near the OLT end) the optical splitter 221 may be a forward test signalTo enhance 8 times, the detection capability can be improved by 5 × log ₁₀ (8) (about 4.5 dB). The equivalent splitting ratio of the splitter 221 can be reduced by about

The multiple (about 2.8) is that the 1 × 8 splitter can be detected only by the ONU-side OTDR having the detection capability of detecting the 1 × 3 splitter.

As can be seen from the embodiment corresponding to fig. 2, the test instruction sent by the OLT to the ONU may or may not carry eqd or eqd, and in addition, the sending of the test instruction by the OLT to the ONU may further include configuring OTDR test parameters of the ONU, or may further include test start time, test end time, test duration, or the like. In addition, in some scenarios, the OTDR test signal on the ONU side and the ONU data transceiver share a component, for example, a laser for transmitting and receiving ONU uplink data is used as a laser for transmitting the OTDR test signal; in some scenarios, the OTDR on the ONU side uses an independent wavelength, that is, a transceiver device of the test signal of the OTDR is completely independent from an optical device of the ONU that transmits and receives data. When the OTDR test signal on the ONU side and the ONU transmit/receive data share a component, in order to avoid that the ONU not participating in the OTDR test reports data and may affect the test, the ONU not participating in the test needs to turn off its laser. In addition, in order to further improve the detection capability of the OTDR, after receiving the OTDR test data reported by the ONU, the OLT may perform fusion processing on the data, and the ONU may further dynamically adjust a gain of a transimpedance amplifier (TIA) and a gain of a Photo Diode (PD), which are described in detail below.

Fig. 4 is a schematic flowchart of another testing method provided in the embodiment of the present application.

As shown in fig. 4, a testing method may include the steps of:

401. the OLT sends configuration information to the ONU.

And the OLT sends configuration information to the N ONUs integrated with the OTDR, wherein N is a positive integer not greater than 1, namely the OLT sends the configuration information to not less than two ONUs integrated with the OTDR. The configuration information is used to configure test parameters of the OTDR, where the test parameters may include eqd or may not include eqd, and eqd in step 401 may be understood with reference to the description of eqd in the embodiment corresponding to fig. 2, and will not be described repeatedly here. The test parameters may also include one or more of the following: the width of the pulse of the test signal, the number of tests (e.g. how many times the test signal is configured to be sent by the OTDR), the pattern of the test signal (pulse, sequence, sine wave, etc.). It should be noted that in an actual application scenario, the OTDR test parameters of the ONU may be configured according to actual needs, and are not limited to the above listed test parameters.

402. And the OLT informs the N ONUs to synchronously start the OTDR test.

The OLT notifies N ONUs to start testing in a first testing time window according to a command issued by an upper management or service system (such as reported to a network management system server) or according to a command issued locally by the OLT or when a triggering condition is met (a pre-configured triggering condition), wherein N is a positive integer greater than 1. The description of the first testing time window in the embodiment corresponding to fig. 2 may be referred to for understanding, and details are not repeated here. For example, at least two ONUs may be notified to synchronously start an OTDR test within the first test time window. The OLT may notify the at least two ONUs of starting the OTDR test synchronously through a first message, which may include, for example, a test start time, a test end time, or a test duration. The first message may be a broadcast or multicast message, for example, when the first message is a broadcast message, the first message may be received by all ONUs participating in the test, when the first message is a multicast message, the first message may be received by a plurality of ONUs in the group, and the first message may also be a unicast message.

In a specific embodiment, the first message may be a Dynamic Bandwidth Allocation (DBA) or an Operation Administration and Maintenance (OAM) message. Specifically, when the first message is a DBA message, in GPON, the first message is a bandwidth map (BWMAP), and in EPON or 10G EPON, the first message is a gate message. When the first message is an OAM message, in the GPON, the first message is an optical network terminal management and control interface (ONU management and cONUrol interface, OMCI) message or a Physical Layer Operation Administration Maintenance (PLOAM) message.

It should be noted that, step 401 and step 402 may be executed separately or simultaneously, for example, the OLT may further include configuration information in a message that the OLT notifies the ONUs to start the OTDR synchronously, in other words, the first message may also carry the configuration information described in step 201, that is, the OLT sends the configuration information to the N ONUs through one test instruction, and notifies the N ONUs to start the test of the OTDR. In addition, it should be noted that, if step 401 and step 402 are separately executed, the step 401 and step 402 are not performed in a sequential manner, for example, the OLT may pre-configure the test parameters of the OTDR and then notify the ONU to start the OTDR test synchronously, or the OLT may first notify the ONU to start the OTDR test synchronously and then send the configuration information to the ONU.

403. The OLT instructs the ONU which does not participate in the OTDR test to turn off the optical device for transmitting and receiving data.

The ONU may carry a status indication when registering with the OLT, and the OLT may determine whether the OTDR transmit/receive test signal on the ONU side and the ONU transmit/receive data share a component according to the status indication, or the OLT may determine whether the OTDR transmit/receive test signal on the ONU side and the ONU transmit/receive data share a component by reading the identification information of the ONU. It should be noted that how the OLT determines whether the OTDR test signal on the ONU side and the ONU transmit/receive data share a component is not the invention point of this solution, and in the prior art, how to determine whether the OTDR test signal on the ONU side and the ONU transmit/receive data share a component may be adopted in the embodiments of the present application.

If the component is shared by the OTDR test signal at the ONU side and the ONU transmit and receive data, for example, a laser device for transmitting and receiving ONU uplink data is used as a laser device for transmitting the OTDR test signal, the OLT instructs the ONU not participating in the OTDR test to turn off the laser device, that is, instructs the ONU not participating in the OTDR test to not transmit the uplink signal, or does not authorize the ONU not participating in the OTDR test to transmit the uplink signal. If the OTDR of the ONU side adopts an independent wavelength, that is, the optical devices for transmitting and receiving the OTDR and the data are completely independent, the OLT may continue to perform uplink authorization on all ONUs.

404. And the first ONU sends a first test signal of the OTDR in a first test time window according to the equivalent time delay.

It can be understood by referring to step 202 in the embodiment corresponding to fig. 2, and the detailed description is not repeated here.

405. And after the first ONU finishes the test, sending test data to the OLT.

And after the first ONU finishes the test, the first ONU exits the test state and sends test data to the OLT.

In a specific embodiment, the first ONU may further analyze the test data and then send the analyzed test data to the OLT, and specifically, the first ONU may perform one or more of the following operations on the test data, including filtering the test data, logarithm-taking the test data, performing event identification according to the test data, and identifying the splitter position according to the test data.

It should be noted that, in a specific embodiment, after the first ONU completes the test, the first ONU may actively send the test data to the OLT. For example, in a specific embodiment, after waiting for at least a first duration, the OLT instructs the ONU to report the test data. And the OLT instructs the ONU to report the data after the first duration is not less than the first test time window, namely the first test time window is ended. If the OTDR at the ONU side is realized by adopting an independent optical device, the ONU can still report data through the data channel during the OTDR test period. In a specific embodiment, the OLT may also know whether the OTDR test of the ONU side is completed by querying the OTDR test state of the ONU side, and if so, may require or request the ONU to report the test data.

406. The OLT instructs the ONU which does not participate in the OTDR test to turn on the optical device for transmitting and receiving data.

For the ONU which receives the instruction to turn off its laser, the OLT instructs the ONU which does not participate in the OTDR test to turn on its laser again after the other ONUs complete the test. In this embodiment of the present application, after the first test time window, the OLT instructs the ONU not participating in the OTDR test to turn on its optical device for receiving and transmitting data. The description of the first testing time window in the embodiment corresponding to fig. 2 can be understood with reference to the first testing window, and the detailed description is not repeated here.

In a specific embodiment, steps 402 to 406 may be repeated multiple times, for example, opening the first test time window may affect uplink data transmission of an ONU that shares a transceiver with the OTDR on the ONU side (data cannot be uploaded during testing), and in order to avoid affecting data communication, one test window cannot be too long. However, the test window is too short, the number of times of OTDR test is too small, and the OTDR performance is limited. In order to comprehensively solve the influence of the OTDR performance and the data communication, a mode of opening the test window for many times without opening the test window for an excessively long time each time may be adopted, for example, the flow may be windowing test, data communication, re-windowing test, and re-data communication, that is, the average number of times is increased by multiple windowing, and after the required average number of times is completed, data is reported.

In addition, how the OTDR performs the test is not the point of the invention of the present application, and in the prior art, how the OTDR obtains the test data may be adopted in the embodiments of the present application, for example, in the first test time window, the OTDR receives and monitors the backscattered and reflected signals, and obtains the attenuation curve of the line through calculation. According to different types of the transmitted excitation signal, different processing modes are required, for example, pulse type excitation pulse of common OTDR and processing method thereof; frequency sweep excitation signals and associated processing methods, and the like. During the first test time, the OTDR may perform one or more measurements as needed.

In a specific embodiment, the OLT reports the test data reported by the ONU to an upper management or service system (e.g., to a network management system server), and the upper management or service system analyzes and processes the test data. Or the OLT locally analyzes and processes the test data (for example, filters, logarithms, identifies faults on the line, etc.), and uploads the processed data or results to an upper management or service system.

As can be seen from the embodiment corresponding to fig. 4, if the OTDR test signal on the ONU side and the ONU transmit and receive data share a component, for example, a laser that receives and transmits ONU uplink data is used as a laser that transmits the OTDR test signal, the OLT instructs the ONU that does not participate in the OTDR test to turn off its laser.

Fig. 5 is a schematic flowchart of another testing method provided in the embodiment of the present application.

As shown in fig. 5, a testing method may include the steps of:

501. and the OLT sends a test instruction to the N ONUs integrated with the OTDR.

502. And the first ONU sends a first test signal of the OTDR in a first test time window according to the equivalent time delay.

Step 501 and step 502 can be understood by referring to steps 201 and 202 in the embodiment corresponding to fig. 2, and are not repeated here.

503. And the OLT receives the OTDR test data sent by the N ONUs.

504. And the OLT segments the received test data according to the positions of the M-level optical splitters.

As mentioned above, a multi-stage optical splitter may be included in the PON system, for example, M stages of optical splitters are included in the PON system, where M is a positive integer, and the OLT segments the received test data according to the positions of the M stages of optical splitters. For example, there is a section between every two optical splitters or a section between the optical splitter and the OLT.

505. The OLT determines the average value of the first piece of data.

The first section of data is data between any one-stage optical splitter in the M-stage optical splitters and the OLT or data between any two-stage optical splitters in the M-stage optical splitters. For example, if M is 1, that is, the PON system includes only one first-stage optical splitter, the OLT determines the position of the first-stage optical splitter after receiving the test data, intercepts the test data (such as an optical fiber curve) after the first-stage optical splitter (seen from the ONU side), that is, intercepts the distance from the first-stage optical splitter to the OLT, and determines the average value of the test data of the distance. If M is 2, the PON system includes a first splitter and a second splitter. The OLT may determine the positions of the two stages of optical splitters first, and the OLT may identify which ONUs are in the same second-stage optical splitter, accumulate their data after the second-stage optical splitter (near the OLT side), identify the positions of the first-stage optical splitters, and finally average the test data (such as trunk optical fiber curves) corresponding to the trunks of all ONUs. Assuming that N ONUs belong to the same optical splitter and all participate in the test, the detection capability can be further improved by averaging the test data. The averaging process is performed to eliminate random noise in the OTDR test process and obtain waveforms with higher signal-to-noise ratio. The principle is briefly explained below, in the OTDR test curve, the reflected signal after each pulse output is sampled, and multiple samples are averaged to eliminate random events, and the longer the averaging time is, the closer the noise level is to the minimum value, the larger the dynamic range is.

As can be seen from the embodiment corresponding to fig. 5, the OLT enables OTDR synchronization testing on one or more ONUs, and the test signal of the optical splitter is enhanced, and in addition, an average value is calculated for data between any one of the M-stage optical splitters and the OLT or between any two of the M-stage optical splitters, so that the testing capability of the OTDR before the optical splitters can be further improved.

In order to further improve the testing capability of the OTDR, the ONU may further dynamically adjust the gain of a transimpedance amplifier (TIA) and the gain of a Photodetector (PD). When the OTDR test is carried out on the ONU side, the test signal passes through 1 multiplied by 2 ^P In the case of an optical splitter with a splitting ratio (P is a positive integer), attenuation of about (3 × P) dB occurs, and an echo signal is attenuated by (3 × P) dB, so that the intensity of backward rayleigh scattered signals received by the OTDR receiver before and after the optical splitter differs by (6 × P) dB (without considering other factors). When the splitting ratio of the optical splitter is 1 × 8(P ═ 3), the intensity of the backward rayleigh scattering signal received by the OTDR receiver after and before the optical splitter differs by 18 dB. The OTDR receiver needs a very large dynamic range to correctly receive the backward rayleigh scattered signal (or echo signal) before and after the splitter,making receiver design difficult or costly. Currently, to maintain the linear relationship, the gain of the TIA is fixed or the bias of the PD is fixed during testing. The gain of the TIA or PD must be set at a suitable value to cover both the echo signal of the drop fiber (not saturated) and the echo signal of the ODN before the splitter. Resulting in poor selection or less than optimal performance of the TIA or PD gain. How to dynamically adjust the gain of a transimpedance amplifier (TIA) and the gain of a Photodetector (PD) of an ONU to further improve the OTDR test capability is described below with reference to fig. 6.

Fig. 6 is a schematic flow chart of another testing method provided in the embodiment of the present application.

As shown in fig. 6, a testing method may include the steps of:

601. and the OLT sends a test instruction to the N ONUs integrated with the OTDR.

602. And the first ONU sends a first test signal of the OTDR in a first test time window according to the equivalent time delay.

Step 601 and step 602 can be understood by referring to steps 201 and 202 in the embodiment corresponding to fig. 2, and are not repeated here.

603. And the first ONU starts timing when sending the first test signal.

604. And when the timing time reaches the time corresponding to the M times, increasing the gain of the TIA of the ONU.

The first ONU determines M moments in advance according to the positions of the M-level optical splitters, wherein M is a positive integer. The ONU can obtain the position information of the M-level optical splitter according to the obtained OTDR test curve by starting an OTDR test once. Or when the ONU is turned on, the operator has measured the length of each segment of optical fiber, or obtains the position information of the M-level splitter through remote or local configuration. How to determine the position of the M-level optical splitter by the ONU is not the invention point of this scheme, and in the prior art, the embodiments of this application can be adopted for the scheme of how to determine the position of the M-level optical splitter. In a specific embodiment, the ONT may start the test with a low gain, start timing when the first test signal is transmitted, and adjust the gain of the receive path, for example, increase the gain of the TIA of the ONU, when the timing reaches a time included in the M times. It should be noted that, in a specific embodiment, the gain of the TIA of the ONU is increased when the timing time reaches each of the M times, or the gain of the TIA of the ONU is increased when the timing time reaches some of the M times. In one embodiment, after the test is completed, the gain of the TIA is adjusted to the initial state again.

In a specific embodiment, the method may further include 605, when the timing time reaches a time corresponding to the M times, increasing a gain of the PD of the ONU. In a specific embodiment, if the bias voltage of the PD is adjusted, for example, the bias voltage of an Avalanche Photodiode (APD) is adjusted, since the gain of the APD increases with the increase of the bias voltage, multiple shift positions may be set, so as to implement different gain controls for different scenes of the optical splitter.

The embodiment corresponding to fig. 6 is described below with reference to schematic structural diagrams of ONUs shown in fig. 7 and 8. The ONU shown in fig. 7 or fig. 8 is integrated with the OTDR, and as shown in fig. 7, the OTDR is implemented by using independent wavelengths, that is, data communication and line test use independent optical devices, and a transceiver of a test signal of the OTDR is completely independent from an optical device of the ONU for transceiving data. Alternatively, as shown in fig. 8, it may also be implemented by using a shared optical device, where the OTDR test signal at the ONU side and the ONU transmit and receive data share a component, such as a shared Laser (LD) or a shared laser driver (LD + LDD), that is, the LD or LD + LDD is selected by a switch or multi-path control to operate in a data communication state or an OTDR test state or operate in both the data communication state and the OTDR test state. As shown in fig. 7 and 8, the ONU includes a data communication module and a line test module, where the data communication module includes a passive optical network media access control (PON MAC) module, and when data arrives at the ONU, the MAC layer of the ONU performs address resolution to extract its own data packet and discard other data packets. The data communication module further includes a Limiting Amplifier (LA), and may further include a PD, an LDD, and a TIA. The line test module includes an OTDR processing functional module, TIA, LDD, and PD, a common Laser (LD) in fig. 8, a test signal sent by the OTDR processing functional module is converted into an optical test signal by the LDD driving LD, and sent to the branch optical fiber, and an echo signal is received by the PD, converted into a current signal, amplified by the TIA, converted into a voltage signal, and input to the OTDR processing functional module for sampling and summing. The line test module also includes a gain control interface (gain control) for controlling or selecting the gain of the TIA. The optional gain control interface can be used for controlling the bias voltage of the PD, so as to realize the control of the PD gain.

Assuming that the high gain is 10 times of the low gain, the method provided by the application can reduce the output amplitude swing of the backward rayleigh scattering signal of TIA by 10dB, and can reduce the dynamic range of the circuit (such as amplifier, ADC digital-to-analog converter) inside the OTDR processing function by 10 dB. Therefore, the detection capability of the OTDR on the ONT side on the ODN before the optical splitter can be improved.

In a specific embodiment, the method may further include: 606. and the OLT receives the OTDR test data sent by the N ONUs.

Corresponding to step 606, it may further include 607, the OLT segmenting the received test data according to the position of the M-stage splitter. It may also include 608, the OLT determining an average value of the first piece of data.

Steps 606 to 608 can be understood with reference to steps 503 to 505 in the embodiment corresponding to fig. 5, and are not repeated herein.

Fig. 9 is a schematic flow chart of another testing method provided in the embodiment of the present application.

As shown in fig. 9, a testing method may include the steps of:

901. the OLT sends a test instruction to the first ONU.

Unlike the embodiments corresponding to fig. 2 to fig. 6 described above, in which the OLT controls a plurality of ONUs to start the test synchronously, in the embodiment of the present application, the OLT may control each ONU to perform the test independently.

902. And the OLT receives the OTDR test data sent by the N ONUs.

903. And the OLT segments the received test data according to the positions of the M-level optical splitters.

904. The OLT determines the average value of the first piece of data.

Step 903 and step 904 can be understood by referring to steps 504 and 505 in the implementation corresponding to fig. 5, and are not repeated here.

As can be seen from the embodiment corresponding to fig. 9, the OLT calculates an average value of data between any one of the M-stage optical splitters and the OLT or between any two of the M-stage optical splitters, and the purpose of calculating the average value is to reduce noise, obtain a waveform with a higher signal-to-noise ratio, and improve the capability of the OTDR to test the optical splitters before.

Fig. 10 is a schematic flowchart of a testing method according to an embodiment of the present application.

As shown in fig. 10, a testing method may include the steps of:

1001. the OLT sends a test instruction to the first ONU.

Unlike the OLT controlling the synchronous start-up test of multiple ONUs in the embodiments corresponding to fig. 2 to fig. 6, in the embodiment of the present application, the OLT may control each ONU to perform the test independently.

1002. And the first ONU starts timing when sending the first test signal.

1003. And when the timing time reaches the time corresponding to the M times, increasing the gain of the TIA of the ONU.

In a specific embodiment, the method may further include 1004 increasing a gain of the PD of the ONU when the timing time reaches a time corresponding to the M times.

Step 1003 and step 1004 can be understood by referring to steps 604 and 605 in the embodiment corresponding to fig. 6, and are not repeated here.

In a specific embodiment, the method may further include 1005, where the OLT receives OTDR test data sent by the N ONUs.

Corresponding to step 1005, it may further include 1006, the OLT segmenting the received test data according to the location of the M-stage splitter. And 1007, the OLT determines the average value of the first section of data.

Steps 1005 to 1007 can be understood by referring to steps 503 to 505 in the embodiment corresponding to fig. 5, and are not repeated herein.

As can be seen from the embodiment corresponding to fig. 10, the gain of the TIA or PD is dynamically adjusted by setting M times according to the position of the M-stage optical splitter, so that the problem that the gain of the TIA or PD must be set to a proper value to cover both the echo signal of the branched optical fiber (which cannot be saturated) and the echo signal of the ODN in front of the optical splitter, which results in poor selection of the gain of the TIA or PD or failure in performing the optimal performance, is solved.

The above-mentioned scheme provided by the embodiment of the present application is introduced mainly from the perspective of interaction between the OLT and the ONU. It is understood that, in order to implement the above functions, the OLT and the ONU include corresponding hardware structures and/or software modules for performing the respective functions. Those of skill in the art will readily appreciate that the various illustrative modules and algorithm steps described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is performed as hardware or computer software drives hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

Described in terms of hardware structures, the OLT and the ONU in fig. 2 to 10 may be implemented by one entity device, may also be implemented by multiple entity devices together, and may also be a logic function module in one entity device, which is not specifically limited in this embodiment of the present application.

For example, the OLT may be implemented by the communication device in fig. 11. Fig. 11 is a schematic diagram of a hardware structure of an OLT according to an embodiment of the present application. The method comprises the following steps: a communication interface 1101 and a processor 1102, and may also include a memory 1103.

The communication interface 1101 may use any transceiver or the like for communicating with other devices or communication networks.

The processor 1102 includes, but is not limited to, one or more of a Central Processing Unit (CPU), a Network Processor (NP), an application-specific integrated circuit (ASIC), or a Programmable Logic Device (PLD). The PLD may be a Complex Programmable Logic Device (CPLD), a field-programmable gate array (FPGA), a General Array Logic (GAL), or any combination thereof. The processor 1102 is responsible for the communication link 1104 and general processing and may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The memory 1103 may be used to store data used by the processor 1102 in performing operations.

The memory 1103 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a Random Access Memory (RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compact disc, laser disc, optical disc, digital versatile disc, blu-ray disc, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited to such. The memory may be separate and coupled to the processor 1102 via a communication link 1104. The memory 1103 may also be integrated with the processor 1102. If the memory 1103 and the processor 1102 are separate devices, the memory 1103 and the processor 1102 may be coupled together, for example, the memory 1103 and the processor 1102 may communicate via a communication line. The communication interface 1101 and the processor 1102 may communicate via a communication line, and the communication interface 1101 may also be directly connected to the processor 1102.

The communication lines 1104 may include any number of interconnected buses and bridges, the communication lines 1104 linking together various circuits including one or more processors 1102, represented by the processor 1102, and memory, represented by the memory 1103. The communication lines 1104 may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein.

In a specific embodiment, the OLT may include: the optical network unit comprises a communication interface, a first Optical Time Domain Reflectometer (OTDR) and N Optical Network Units (ONUs) integrated with the OTDR, wherein the communication interface is used for sending a test instruction to the N Optical Network Units (ONUs) integrated with the OTDR, the test instruction is used for indicating the N ONUs to send test signals of the OTDR in a first test time window, the test signals sent by the N ONUs synchronously reach the same optical splitter, and N is a positive integer greater than 1.

In a specific embodiment, the test instruction is specifically configured to instruct the N ONUs to send a test signal of the OTDR within the first test time window according to the equivalent delay eqd, and eqd is configured to ensure that the test signals sent by the N ONUs arrive at the same optical splitter synchronously.

In one particular embodiment, eqd is sent to N ONUs via test instructions.

In a specific embodiment, the communication interface is further configured to receive OTDR test data sent by the N ONUs; the OLT may further comprise a memory for storing computer-readable instructions; further comprising a processor coupled to the memory, the processor configured to: segmenting test data received by a communication interface according to the position of an M-level optical splitter, wherein M is a positive integer; and the processor is further used for determining an average value of first-segment data, wherein the first-segment data is data between any one-stage optical splitter in the M-stage optical splitters and the OLT or data between any two-stage optical splitters in the M-stage optical splitters.

In a specific embodiment, the communication interface is specifically configured to send a test instruction to the ONU through a first message, where the first message is any one of a dynamic bandwidth allocation DBA message, an operation, management, and maintenance OAM message, a bandwidth mapping BWMAP information, an optical network terminal management and control interface OMCI message, and a physical layer operation, management, and maintenance PLOAM message.

In a specific embodiment, the processor is further configured to determine that an optical device, which is connected to the OLT and used for transceiving data, of a target ONU is the same as an optical device, which is integrated on the ONU and used for transceiving signals, of the OTDR; and the communication interface is further used for indicating the target ONU to close an optical device for receiving and transmitting data by the OLT if the target ONU determined by the processor does not participate in the OTDR test.

In a specific embodiment, the communication interface is further configured to instruct the at least two ONUs to report the test data after waiting for at least a first time period, where the first time period is not less than a first test time window.

In the embodiment of the present application, the communication interface may be regarded as a transceiver unit of the OLT, the processor having a processing function may be regarded as a processing unit of the OLT, and the memory may be regarded as a storage unit of the OLT. As shown in fig. 12, the OLT may include a transceiving unit 1210, a processing unit 1220, and a storage unit 1230. A transceiver unit may also be referred to as a transceiver, a transceiving device, etc. A processing unit may also be referred to as a processor, a processing board, a processing module, a processing device, or the like. Optionally, a device in the transceiver unit 1210 for implementing a receiving function may be regarded as a receiving unit, and a device in the transceiver unit 1210 for implementing a transmitting function may be regarded as a transmitting unit, that is, the transceiver unit 1210 includes a receiving unit and a transmitting unit. A transceiver unit may also sometimes be referred to as a transceiver, transceiving circuitry, or the like. A receiving unit may also be referred to as a receiver, a receiving circuit, or the like. A transmitting unit may also sometimes be referred to as a transmitter, or a transmitting circuit, etc.

In a specific embodiment, the transceiver unit 1210 is configured to perform the transceiving operation on the OLT side in step 201 and step 202 in fig. 2, and/or the transceiver unit 1210 is further configured to perform other transceiving steps on the OLT side in the embodiment corresponding to fig. 2.

In a specific embodiment, the transceiver unit 1210 is configured to perform the transceiving operation on the OLT side in steps 401 to 406 in fig. 4, and/or the transceiver unit 1210 is further configured to perform other transceiving steps on the OLT side in the embodiment corresponding to fig. 4.

In a specific embodiment, the transceiver unit 1210 is configured to perform the transceiving operation on the OLT side in steps 501 to 503 in fig. 5, and/or the transceiver unit 1210 is further configured to perform other transceiving steps on the OLT side in the embodiment corresponding to fig. 5. A processing unit 1220, configured to perform the processing operations on the OLT side in step 504 and step 505 in fig. 5, and/or the processing unit 1220 is further configured to perform other processing steps on the OLT side in the embodiment corresponding to fig. 5.

In a specific embodiment, the transceiver unit 1210 is configured to perform the transceiving operation on the OLT side in step 601, step 602, and step 606 in fig. 6, and/or the transceiver unit 1210 is further configured to perform other transceiving steps on the OLT side in the embodiment corresponding to fig. 6. The processing unit 1220 is configured to perform the processing operations at the OLT side in step 607 and step 608 in fig. 6, and/or the processing unit 1220 is further configured to perform other processing steps at the OLT side in the embodiment corresponding to fig. 6.

In a specific embodiment, the transceiver unit 1210 is configured to perform the transceiving operation on the OLT side in step 901 and step 902 in fig. 9, and/or the transceiver unit 1210 is further configured to perform other transceiving steps on the OLT side in the embodiment corresponding to fig. 9. A processing unit 1220, configured to perform the processing operations at the OLT side in step 903 and step 904 in fig. 9, and/or the processing unit 1220 is further configured to perform other processing steps at the OLT side in the embodiment corresponding to fig. 9.

In a specific embodiment, the transceiver unit 1210 is configured to perform the transceiving operation on the OLT side in step 1001, step 1002, and step 1005 in fig. 10, and/or the transceiver unit 1210 is further configured to perform other transceiving steps on the OLT side in the embodiment corresponding to fig. 10. A processing unit 1220, configured to perform the processing operations at the OLT side in step 1006 and step 1007 in fig. 10, and/or the processing unit 1220 is further configured to perform other processing steps at the OLT side in the embodiment corresponding to fig. 10.

In addition, the ONU can be implemented by the communication device in fig. 13. Fig. 13 is a schematic diagram of a hardware structure of an ONU according to an embodiment of the present application. The method comprises the following steps: communication interface 1301 and processor 1302 may also include memory 1303.

Communication interface 1301 may use any device, such as a transceiver, for communicating with other devices or communication networks, such as an ethernet, a Radio Access Network (RAN), a Wireless Local Area Network (WLAN), etc.

The processor 1302 includes, but is not limited to, one or more of a Central Processing Unit (CPU), a Network Processor (NP), an application-specific integrated circuit (ASIC), or a Programmable Logic Device (PLD). The PLD may be a Complex Programmable Logic Device (CPLD), a field-programmable gate array (FPGA), a General Array Logic (GAL), or any combination thereof. The processor 1302 is responsible for the communication lines 1304 and general processing and may provide a variety of functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory 1303 may be used to store data used by processor 1302 in performing operations.

The memory 1303 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a Random Access Memory (RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compact disc, laser disc, optical disc, digital versatile disc, blu-ray disc, etc.), but is not limited to, magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. The memory may be stand alone and coupled to the processor 1302 via the communication link 1304. Memory 1303 may also be integrated with processor 1302. If the memory 1303 and the processor 1302 are separate devices, the memory 1303 and the processor 1302 are connected, for example, the memory 1303 and the processor 1302 may communicate via a communication line. The communication interface 1301 and the processor 1302 may communicate through communication lines, and the communication interface 1301 may be directly connected to the processor 1302.

The communication lines 1304 may include any number of interconnected buses and bridges, with the communication lines 1304 linking together various circuits including one or more of the processor 1302, as represented by the processor 1302, and memory, as represented by the memory 1303. The communication lines 1304 may also link various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein.

In a specific embodiment, the ONU may include: the optical line terminal OLT comprises a communication interface, an ONU and an ONU, wherein the communication interface is used for receiving a test instruction sent by the optical line terminal OLT, an OTDR is integrated on the ONU, and the test instruction instructs the ONU to start the OTDR test in a first test time window; and the communication interface is further used for sending the test signal of the OTDR in the first test window according to the equivalent time delay eqd.

In a specific embodiment, the method may further include: a memory for storing computer readable storage instructions and a processor coupled to the memory for determining M times based on the M-stage splitter position, M being a positive integer; a communication interface for transmitting a test signal; the processor is also used for starting timing when the communication interface sends the test signal; and the processor is further used for increasing the gain of a TIA (transimpedance amplifier) of the ONU when the timing time reaches the time corresponding to the M times.

In a specific embodiment, the processor is further configured to increase a gain of the photodetector PD of the ONU when the timing time reaches a time corresponding to the M times.

In the embodiment of the present application, the communication interface may be regarded as a transceiver unit of the ONU, the processor having the processing function may be regarded as a processing unit of the ONU, and the memory may be regarded as a storage unit of the ONU. As shown in fig. 14, the ONU includes a transceiving unit 1410, a processing unit 1420, and a storage unit 1430. A transceiver unit may also be referred to as a transceiver, a transceiving device, etc. A processing unit may also be referred to as a processor, a processing board, a processing module, a processing device, or the like. Optionally, a device for implementing the receiving function in the transceiving unit 1410 may be regarded as a receiving unit, and a device for implementing the transmitting function in the transceiving unit 1410 may be regarded as a transmitting unit, that is, the transceiving unit 1410 includes a receiving unit and a transmitting unit. A transceiver unit may also sometimes be referred to as a transceiver, transceiver circuit, or the like. A receiving unit may also be referred to as a receiver, a receiving circuit, or the like. A transmitting unit may also sometimes be referred to as a transmitter, or a transmitting circuit, etc.

In a specific embodiment, the transceiver unit 1410 is configured to perform transceiver operations on the ONU side in step 201 and step 202 in fig. 2, and/or the transceiver unit 1410 is further configured to perform other transceiver steps on the ONU side in the embodiment corresponding to fig. 2.

In a specific embodiment, the transceiver unit 1410 is configured to perform the transceiving operation on the ONU side in steps 401 to 406 in fig. 4, and/or the transceiver unit 1410 is further configured to perform other transceiving steps on the ONU side in the embodiment corresponding to fig. 4.

In a specific embodiment, the transceiver unit 1410 is configured to perform the transceiving operation on the ONU side in steps 501 to 503 in fig. 5, and/or the transceiver unit 1410 is further configured to perform other transceiving steps on the ONU side in the embodiment corresponding to fig. 5.

In a specific embodiment, the transceiver unit 1410 is configured to perform the transceiving operation on the ONU side in step 601, step 602, and step 606 in fig. 6, and/or the transceiver unit 1410 is further configured to perform other transceiving steps on the ONU side in the embodiment corresponding to fig. 6. A processing unit 1420, configured to perform the processing operations on the ONU side in steps 603 to 605 in fig. 6, and/or the processing unit 1420 is further configured to perform other processing steps on the ONU side in the embodiment corresponding to fig. 6.

In a specific embodiment, the transceiver unit 1410 is configured to perform the transceiving operation on the ONU side in step 901 and step 902 in fig. 9, and/or the transceiver unit 1410 is further configured to perform other transceiving steps on the ONU side in the embodiment corresponding to fig. 9.

In a specific embodiment, the transceiver unit 1410 is configured to perform the transceiving operation on the ONU side in step 1001, step 1002, and step 1005 in fig. 10, and/or the transceiver unit 1410 is further configured to perform other transceiving steps on the ONU side in the embodiment corresponding to fig. 10. A processing unit 1420, configured to perform the processing operations on the ONU side in step 1003 and step 1004 in fig. 10, and/or the processing unit 1420 is further configured to perform other processing steps on the ONU side in the embodiment corresponding to fig. 10.

In the above embodiments, all or part of the implementation may be realized by software, hardware, firmware, or any combination thereof. When implemented in software, it may be implemented in whole or in part in the form of a computer program product.

The computer program product includes one or more computer instructions. The procedures or functions described in accordance with the embodiments of the application are all or partially generated when the computer program instructions are loaded and executed on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that a computer can store or a data storage device, such as a server, a data center, etc., that is integrated with one or more available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

Those skilled in the art will appreciate that all or part of the steps in the methods of the above embodiments may be implemented by hardware related to instructions of a program, and the program may be stored in a computer-readable storage medium, and the storage medium may include: ROM, RAM, magnetic or optical disks, and the like.

The test method, the ONU, the OLT, and the communication system provided in the embodiments of the present application are described in detail above, and a specific example is applied in the present application to explain the principle and the implementation of the present application, and the description of the above embodiments is only used to help understand the method and the core idea of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims

1. A method of testing, comprising:

an Optical Line Terminal (OLT) sends a test instruction to N Optical Network Units (ONUs) integrated with an Optical Time Domain Reflectometer (OTDR), wherein the test instruction is used for indicating the N ONUs to send test signals of the OTDR in a first test time window, the test signals sent by the N ONUs synchronously reach the same optical splitter, and N is a positive integer greater than 1;

the test instruction is specifically configured to instruct N ONUs to send a test signal of the OTDR within the first test time window according to an equivalent time delay eqd, where the eqd is configured to ensure that the test signal sent by the N ONUs arrives at the same optical splitter synchronously, and when the N ONUs start an OTDR test, the delay is eqd when the test signal is sent according to a difference in distance from the optical splitter.

2. The method according to claim 1, wherein said eqd is sent to N of said ONUs via said test command.

3. The method according to any one of claims 1 or 2, further comprising:

the OLT receives the OTDR test data sent by N ONUs;

the OLT segments the received test data according to the position of an M-level optical splitter, wherein M is a positive integer;

the OLT determines an average value of first-stage data, wherein the first-stage data is data between any one-stage optical splitter in the M-stage optical splitters and the OLT or data between any two-stage optical splitters in the M-stage optical splitters.

4. Method according to any of claims 1 or 2, wherein the OLT sends test instructions to N optical network units, ONUs, integrated with an optical time domain reflectometry, OTDR, comprising:

the OLT sends a test instruction to the ONU through a first message, wherein the first message is any one of a dynamic bandwidth allocation DBA message, an operation, management and maintenance (OAM) message, a bandwidth mapping (BWMAP) message, an optical network terminal management and control interface (OMCI) message and a physical layer operation, management and maintenance (PLOAM) message.

5. The method according to any one of claims 1 or 2, further comprising:

the OLT determines that an optical device used by a target ONU for transmitting and receiving data and an optical device used by the OTDR integrated on the ONU are the same;

and if the target ONU does not participate in the OTDR test, the OLT instructs the target ONU to close an optical device for receiving and transmitting data.

6. The method according to claim 1 or 2, characterized in that the method further comprises:

and the OLT instructs at least two ONUs to report test data after waiting for at least a first time length, wherein the first time length is not less than the first test time window.

7. A method of testing, comprising:

an Optical Network Unit (ONU) receives a test instruction sent by an Optical Line Terminal (OLT), an Optical Time Domain Reflectometer (OTDR) is integrated on the ONU, the test instruction instructs N ONUs to start the test of the OTDR in a first test time window, and N is a positive integer greater than 1;

the ONU sends the OTDR test signal in the first test window according to the equivalent time delay eqd, when the N ONUs start the OTDR test, the time delay for sending the test signal is set to be eqd according to the difference in distance from the optical splitter, and the eqd is configured to ensure that the test signals sent by the N ONUs arrive at the same optical splitter synchronously.

8. The method of claim 7, further comprising:

the ONU determines M moments according to the positions of the M-level optical splitters, wherein M is a positive integer;

the ONU starts timing when sending the test signal;

and when the timing moment reaches the moment corresponding to the M moments, increasing the gain of a TIA (transimpedance amplifier) of the ONU.

9. The method according to claim 7 or 8, characterized in that the method further comprises:

and when the timing time reaches the time corresponding to the M times, increasing the gain of the photoelectric detector PD of the ONU.

10. An optical line termination, OLT, comprising:

a transceiver unit, configured to send a test instruction to N optical network units ONUs integrated with an OTDR, where the test instruction is used to instruct the N ONUs to send a test signal of the OTDR within a first test time window, the test signal sent by the N ONUs synchronously reach a same optical splitter, and N is a positive integer greater than 1;

the test instruction is specifically configured to instruct the N ONUs to send the test signal of the OTDR within the first test time window according to an equivalent time delay eqd, where the eqd is configured to ensure that the test signal sent by the N ONUs arrives at the same optical splitter synchronously, and when the N ONUs start an OTDR test, the delay is eqd when sending the test signal according to different distances from the optical splitter.

11. The OLT of claim 10, wherein the eqd is configured to send the N ONUs with the test instruction.

12. The OLT of claim 10 or 11,

the transceiver unit is further configured to receive test data of the OTDR sent by the N ONUs;

the OLT further comprises:

the processing unit is used for segmenting the test data received by the transceiving unit according to the position of an M-level optical splitter, wherein M is a positive integer;

the processing unit is further configured to determine an average value of first segment data, where the first segment data is data between any one of the M-stage optical splitters and the OLT or data between any two of the M-stage optical splitters.

13. The OLT of claim 10 or 11,

the transceiver unit is specifically configured to send a test instruction to the ONU through a first message, where the first message is any one of a dynamic bandwidth allocation DBA message, an operation, administration, and maintenance OAM message, a bandwidth mapping BWMAP message, an optical network terminal management and control interface OMCI message, and a physical layer operation, administration, and maintenance PLOAM message.

14. The OLT of claim 10 or 11, characterized in that the OLT further comprises a processing unit,

the processing unit is further configured to determine that an optical device, which is connected to the OLT and used for transmitting and receiving data, of a target ONU is the same as an optical device, which is integrated on the ONU and used for transmitting and receiving signals, of the OTDR;

the transceiving unit is further configured to instruct, by the OLT, the target ONU to turn off an optical device used for transceiving data if the target ONU determined by the processing unit does not participate in the OTDR test.

15. The OLT of claim 10 or 11,

the transceiver unit is further configured to instruct at least two ONUs to report test data after waiting for at least a first time period, where the first time period is not less than the first test time window.

16. An optical network unit, ONU, comprising:

a transceiver unit, configured to receive a test instruction sent by an optical line terminal OLT, where an optical time domain reflectometer OTDR is integrated on the ONU, and the test instruction instructs N ONUs to start a test of the OTDR within a first test time window, where N is a positive integer greater than 1;

the transceiver unit is further configured to send a test signal of the OTDR in a first test window according to an equivalent time delay eqd, when the N ONUs start an OTDR test, delay different times when sending the test signal is the eqd according to different distances from an optical splitter, and the eqd is configured to ensure that the test signals sent by the N ONUs arrive at the same optical splitter synchronously.

17. The ONU of claim 16, further comprising:

the processing unit is used for determining M moments according to the positions of the M-level optical splitters, wherein M is a positive integer;

the receiving and transmitting unit is used for transmitting the test signal;

the processing unit is further configured to start timing when the transceiver unit sends the test signal;

the processing unit is further configured to increase a gain of a transimpedance amplifier TIA of the ONU when the timing reaches a time corresponding to the M times.

18. The ONU of claim 17,

the processing unit is further configured to increase a gain of the photodetector PD of the ONU when the timing time reaches a time corresponding to the M times.

19. A passive optical network system, comprising: an optical line terminal OLT and N optical network units ONU, wherein the OLT is connected to N of the ONUs in a point-to-multipoint manner through an M-stage optical splitter, wherein N is a positive integer, M is a positive integer, the OLT is the OLT described in any one of claims 10 to 15, the ONUs are the ONUs described in any one of claims 16 to 18, and the M-stage optical splitter is configured to distribute data sent by the OLT to the N of the ONUs and to concentrate the data sent by the N of the ONUs to the OLT.

20. The passive optical network system according to claim 19, wherein test signals transmitted by N ONUs arrive synchronously at any one of the M-stage optical splitters.

21. A computer-readable storage medium, wherein the instructions, when executed on a computer device, cause the computer device to perform the method of any of claims 1 to 6.

22. A computer-readable storage medium, wherein the instructions, when executed on a computer device, cause the computer device to perform the method of any of claims 7 to 9.