CN117674986A

CN117674986A - Method, device and system for determining topology of optical access network

Info

Publication number: CN117674986A
Application number: CN202211086278.6A
Authority: CN
Inventors: 林华枫; 曾小飞; 周恩宇
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-09-06
Filing date: 2022-09-06
Publication date: 2024-03-08
Also published as: WO2024051286A1

Abstract

The method, the device and the system for determining the topology of the optical access network do not need to modify the optical terminal, can reduce the implementation complexity and reduce the resource waste caused by manual modification. According to the method, the principle that different ONTs send optical signals in different time slots is utilized, different branches in the optical splitter correspond to different wavelengths, and detection optical signals of different wavelengths are sent through the OLT, so that the change condition of the received optical signals is monitored in different time slots, and the binding relation between the optical terminal corresponding to the changed time slot and the port of the optical splitter branch corresponding to the wavelength is determined. The method and the device mainly utilize the cross modulation effect generated in the branch of the optical splitter by the detection optical signal and the uplink optical signal of the optical terminal to enable the optical signal received by the OLT to change.

Description

Method, device and system for determining topology of optical access network

Technical Field

The present invention relates to the field of optical communications technologies, and in particular, to a method, an apparatus, and a system for determining an optical access network topology.

Background

A passive optical network (passive optical network, PON) system comprises an optical line terminal (optical line terminal, OLT), an optical distribution network (optical distribution network, ODN) and a plurality of optical terminals, such as optical network units (optical network unit, ONUs) or optical network terminals (optical network termination, ONTs), located on the subscriber side.

The optical signals of the PON system upstream and downstream can be transmitted in the same optical fiber. The optical signals in the downstream direction (from the OLT to the optical terminals) operate in a time division multiplexed (time division multiplexing, TDM) manner, and the data transmitted by the OLT is broadcast to all the drop fibers to all the optical terminals. The optical signals in the upstream direction (optical terminal to OLT) operate in a time division multiple access (time division multiple access, TDMA) mode, the optical terminals transmitting only in authorized time slots.

The ODN may transmit optical signals between the OLT and a plurality of optical terminals. The ODN topology is relatively complex, for example, the ODN includes one or more stages of optical splitters for connecting the OLT and the plurality of optical terminals, but the connection relationship between the optical terminals and the optical splitters in the ODN is not always unchanged, so that difficulties are brought to fault location and fault elimination for operation and maintenance personnel.

Disclosure of Invention

The embodiment of the application provides a method, a device and a system for determining the topology of an optical access network, which do not need to modify ONTs, thereby reducing the complexity of implementation.

In a first aspect, an embodiment of the present application provides a method for determining an optical access network topology, where the optical access network includes a plurality of optical terminals, where the plurality of optical terminals are optically connected to different ports of an optical splitter in the optical access network in a one-to-one correspondence manner, and the method includes: continuously transmitting a detection optical signal of a first wavelength, and controlling the plurality of optical terminals to respectively transmit uplink optical signals on time slots corresponding to each optical terminal; the first wavelength corresponds to a first port of the optical splitter, and different ports of the optical splitter correspond to different wavelengths; detecting the power of the reflected optical signal of the detected optical signal in the optical signals received on the time slots respectively corresponding to the plurality of optical terminals; determining an optical terminal connected with the first port corresponding to the first wavelength according to the relation between a time window in which the change of the power of the reflected optical signal of the detected optical signal is detected in the received optical signal and time slots respectively corresponding to the plurality of optical terminals; wherein the power variation of the reflected light signal of the detected light signal detected in the received light signal is: and the uplink optical signal of one optical terminal is generated by generating a cross gain modulation effect or a cross attenuation modulation effect in the connecting branch circuit for the detection optical signal and the optical signal obtained by reflecting the detection optical signal by the optical filter in the connecting branch circuit of the optical splitter and the one optical terminal.

The optical filter disposed in the ODN may be a reflection type filter or a transmission type filter, i.e., a reflection type filter or a transmission type filter is disposed on a branch optical fiber of the optical splitter. And the optical head end continuously transmits the detection optical signals with specific wavelengths, and the optical head end controls a plurality of optical terminals in the optical access network to respectively transmit uplink optical signals on corresponding time slots. The optical signal of the ONT generates a cross gain modulation effect or a cross attenuation modulation effect on the reflected optical signal of the probe optical signal in the gain component of the branch, so that the optical head end detects that the power of the reflected optical signal of the probe optical signal is changed (e.g., increased or decreased) compared with the power of the probe optical signal. Since different optical filters correspond to different wavelengths or combinations of wavelengths, optical signals of different wavelengths or combinations of wavelengths can be reflected or transmitted. The optical filters with different wavelengths correspond to different ports, and then the optical head end can realize the binding of the ports of the optical splitter and the ONT according to the wavelength of the detected optical signal and the time of power change. The ONT does not need to be modified, and the complexity can be reduced.

The optical connection between the two devices can be used for realizing the transmission of optical signals between the two devices. The optical connection may be through optical fibers, optical waveguides, or other optical media.

In one possible design, determining the optical terminal to which the first port corresponding to the first wavelength is connected according to a relation between a time window in which a change in power of a reflected optical signal of a detected optical signal is detected in received optical signals and time slots respectively corresponding to the plurality of optical terminals, includes:

and when the time window for determining that the power of the reflected optical signal detected in the received optical signal is changed is located in a first time slot, determining that a first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength.

In a second aspect, an embodiment of the present application provides a determining apparatus of an optical access network topology, where the optical access network includes a plurality of optical terminals, the plurality of optical terminals are optically connected to a plurality of ports of an optical splitter in the optical access network in a one-to-one correspondence manner, the apparatus includes a media access control MAC unit, a wavelength tunable laser, a photodetector, and a circulator, a first port of the circulator is optically connected to the wavelength tunable laser, a second port of the circulator is optically connected to the optical splitter, and a third port of the circulator is optically connected to the photodetector;

The MAC unit is used for controlling the plurality of optical terminals to respectively send uplink optical signals on the time slots corresponding to each optical terminal;

the wavelength-adjustable laser is used for continuously sending a detection light signal with a first wavelength to the beam splitter through the circulator;

the photoelectric detector is used for detecting the power of a reflected optical signal of the detection optical signal in the optical signals received by the circulator on the time slots corresponding to the plurality of optical terminals respectively;

the MAC unit is further configured to determine, according to a relationship between a time window in which a change in power of a reflected optical signal of the detected optical signal is detected in the received optical signal and time slots corresponding to the plurality of optical terminals, an optical terminal to which the first port corresponding to the first wavelength is connected;

wherein the power change of the reflected light signal of the detected light signal is detected in the received light signal is: and the uplink optical signal of one optical terminal is generated by generating a cross gain modulation effect or a cross attenuation modulation effect in the connecting branch circuit for the detection optical signal and the optical signal obtained by reflecting the detection optical signal by the optical filter in the connecting branch circuit of the optical splitter and the one optical terminal.

In one possible design, the MAC unit is specifically configured to:

and when the time window for determining the change of the power of the reflected optical signal is positioned in a first time slot, determining that a first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength.

In a third aspect, an embodiment of the present application provides another method for determining a topology of an optical access network, where the optical access network includes a plurality of optical terminals, where the plurality of optical terminals are optically connected to a plurality of ports of an optical splitter in the optical access network in a one-to-one correspondence manner, and the method includes: continuously transmitting a pump optical signal with a first wavelength, and controlling the plurality of optical terminals to respectively transmit an uplink optical signal on a time slot corresponding to each optical terminal; the first wavelength corresponds to a first port of the optical splitter, and different ports of the optical splitter correspond to different wavelengths; measuring the received power of the uplink optical signals received on the time slots respectively corresponding to the plurality of optical terminals; determining an optical terminal connected with the first port corresponding to the first wavelength according to the change condition of the received power of each optical terminal in the plurality of optical terminals and the uplink baseline received power of each optical terminal; the uplink baseline receiving power of one optical terminal is the receiving power of the uplink optical signal of the one optical terminal under the condition that the pump optical signal does not enter the optical fiber between the optical splitter and the one optical terminal; the change of the receiving power of one optical terminal and the uplink baseline receiving power of the one optical terminal is generated by the cross gain modulation effect or the cross attenuation modulation effect generated by the pump optical signal on the uplink optical signal of the one optical terminal in the connection branch of the optical splitter and the first optical terminal.

The optical filter deployed in the ODN may be a reflective filter or a transmissive filter. And the optical head end controls a plurality of optical terminals in the optical access network to respectively send uplink optical signals on corresponding time slots. The optical signal for detection generates a cross gain modulation effect or a cross attenuation modulation effect on the uplink optical signal in the gain component of the branch, so that the power of the uplink optical signal of the optical terminal changes (e.g., increases or decreases). Since different optical filters correspond to different wavelengths or combinations of wavelengths, optical signals of different wavelengths or combinations of wavelengths can be reflected or transmitted. The optical filters with different wavelengths correspond to different ports, and then the optical head end can realize the binding of the ports of the optical splitter and the ONT according to the wavelength of the detection optical signal and the time slot of the uplink optical signal with power change.

In one possible design, the determining, according to a change of the received power of each optical terminal in the plurality of optical terminals and the uplink baseline received power of each optical terminal, the optical terminal to which the first port corresponding to the first wavelength is connected includes:

When the difference between the power of the uplink optical signal received in the first time slot and the uplink baseline receiving power of the first optical terminal corresponding to the first time slot is greater than or equal to a set threshold value, and the difference between the power of the uplink optical signal received in any time slot except the first time slot and the uplink baseline receiving power of the optical terminal corresponding to any other time slot is less than the set threshold value, determining that the first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength; or,

when the difference between the power of the uplink optical signal received in the first time slot and the uplink baseline receiving power of the first optical terminal corresponding to the first time slot is smaller than a set threshold, and the difference between the power of the uplink optical signal received in any time slot except the first time slot and the uplink baseline receiving power of the optical terminal corresponding to any other time slot is larger than or equal to the set threshold, determining that the first optical terminal corresponding to the first time slot and the first port corresponding to the first wavelength are optically connected.

In one possible design, the pump optical signal is obtained by modulating setting information, and the determining, according to a change condition of a received power of each optical terminal in the plurality of optical terminals and an uplink baseline received power of each optical terminal, an optical terminal connected to the first port corresponding to the first wavelength includes:

Determining that a first optical terminal corresponding to a first time slot is optically connected with the first port corresponding to the first wavelength when the difference between the power of an uplink optical signal received in each time slot in a plurality of time slots corresponding to the plurality of optical terminals and the uplink baseline received power of the optical terminal corresponding to each time slot is smaller than a set threshold value and the set information is detected in the uplink optical signal received in the first time slot; or,

and when the set information is detected in the uplink optical signals received in the first time slot, determining that a first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength.

In one possible design, the setting information includes a setting frequency and/or a setting pattern.

In one possible design, the method further comprises:

before continuously transmitting the pump optical signals of the first wavelength, controlling the plurality of optical terminals to respectively transmit uplink optical signals on the time slots corresponding to each optical terminal, and measuring the received power of the uplink optical signals of the plurality of optical terminals to obtain the uplink baseline received power of each optical terminal in the plurality of optical terminals.

In a fourth aspect, an embodiment of the present application provides a device for determining topology of an optical access network, where the optical access network includes a plurality of optical terminals, where the plurality of optical terminals are optically connected to a plurality of ports of an optical splitter in the optical access network in a one-to-one correspondence manner, and the device includes a media access control MAC unit, an optical module, and a wavelength-adjustable laser;

the wavelength-adjustable laser is used for continuously transmitting a detection optical signal with a first wavelength;

the optical module is used for measuring the received power of the uplink optical signals received on the time slots corresponding to the plurality of optical terminals respectively;

the MAC unit determines the optical terminal connected with the first port corresponding to the first wavelength according to the change condition of the received power of each optical terminal in the plurality of optical terminals and the uplink baseline received power of each optical terminal;

the uplink baseline receiving power of one optical terminal is the receiving power of the uplink optical signal of the one optical terminal under the condition that the pump optical signal does not enter the optical fiber between the optical splitter and the one optical terminal; the change of the receiving power of one optical terminal and the uplink baseline receiving power of the one optical terminal is generated by the cross gain modulation effect or the cross attenuation modulation effect generated by the pump optical signal on the uplink optical signal of the one optical terminal in the connection branch of the optical splitter and the first optical terminal.

In one possible design, the MAC unit is specifically configured to:

determining that a first optical terminal corresponding to a first time slot is optically connected with the first port corresponding to the first wavelength when a difference between power of an uplink optical signal received in the first time slot and uplink baseline received power of a first optical terminal corresponding to the first time slot is greater than or equal to a set threshold and a difference between power of an uplink optical signal received in any time slot other than the first time slot and uplink baseline received power of an optical terminal corresponding to any time slot other than the first time slot is less than the set threshold; or,

and when the difference between the power of the uplink optical signal received in the first time slot and the uplink baseline receiving power of the first optical terminal corresponding to the first time slot is smaller than a set threshold value, and when the difference between the power of the uplink optical signal received in any time slot except the first time slot and the uplink baseline receiving power of the optical terminal corresponding to any time slot is larger than or equal to the set threshold value, determining that the first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength.

In one possible design, the pump optical signal is obtained by modulating setting information, and the optical module is further configured to detect the setting information from uplink optical signals received by corresponding time slots of a plurality of optical terminals respectively;

The MAC unit is specifically configured to:

In one possible design, the MAC unit is further configured to control, before continuously transmitting the pump optical signals of the first wavelength, the plurality of optical terminals to transmit uplink optical signals on timeslots corresponding to each of the optical terminals, respectively;

The optical module is further configured to measure the received power of the uplink optical signals of the plurality of optical terminals to obtain an uplink baseline received power of each optical terminal in the plurality of optical terminals.

In a fifth aspect, an embodiment of the present application provides a method for determining an optical access network topology, where the optical access network includes a plurality of optical terminals, where the plurality of optical terminals are optically connected to a plurality of ports of an optical splitter in the optical access network in a one-to-one correspondence manner, and the method includes:

continuously transmitting a pump optical signal with a first wavelength, and controlling the plurality of optical terminals to respectively transmit an uplink optical signal on a time slot corresponding to each optical terminal; the first wavelength corresponds to a first port of the optical splitter, and different ports of the optical splitter correspond to different wavelengths; the pump light signal is obtained through modulation of set information;

detecting the setting information in uplink optical signals received by time slots corresponding to the plurality of optical terminals respectively to obtain a detection result of each time slot;

and determining the optical terminal connected with the first port corresponding to the first wavelength according to the detection result of each time slot.

The optical filter deployed in the ODN may be a reflective filter or a transmissive filter. The pump light signal with specific wavelength is continuously sent at the optical head end. The pump light signal can be modulated by the setting information. Such as by frequency modulation of a set frequency or by pattern modulation of a set pattern. The set frequency may be, for example, a positive rate wave, but other frequencies may be used. The set pattern may be, for example, a spreading code. The optical head end controls a plurality of optical terminals in the optical access network to respectively send uplink optical signals on corresponding time slots. The detection optical signal generates a cross gain modulation effect or a cross attenuation modulation effect on the uplink optical signal in the gain component of the branch, so that the set frequency information or the set code type information in the pump optical signal is modulated on the uplink optical signal of the optical terminal, and further binding between the port of the optical splitter and the ONT can be realized based on the time slot where the uplink optical signal with the set frequency information or the set code type information is detected and the wavelength of the pump optical signal. The ONT does not need to be modified, and the complexity can be reduced.

In one possible design, determining, according to a detection result of each time slot, an optical terminal to which the first port corresponding to the first wavelength is connected, includes:

the uplink optical signals received in the first time slot detect the setting information, and when the uplink optical signals received in any time slot except the first time slot do not detect the setting information, the first optical terminal corresponding to the first time slot is determined to be optically connected with the first port corresponding to the first wavelength; or,

and when the uplink optical signal received in the first time slot does not detect the setting information and the uplink optical signal received in any time slot except the first time slot detects the setting information, determining that the first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength.

In a sixth aspect, an embodiment of the present application provides an apparatus for determining topology of an optical access network, where the optical access network includes a plurality of optical terminals, where the plurality of optical terminals are optically connected to a plurality of ports of an optical splitter in the optical access network in a one-to-one correspondence manner, and the apparatus includes a media access control MAC unit, an optical module, and a wavelength-adjustable laser;

the wavelength-adjustable laser is used for continuously transmitting a detection light signal which has a first wavelength and is modulated with setting information;

the optical module is used for detecting the setting information in uplink optical signals received by time slots corresponding to the plurality of optical terminals respectively to obtain a detection result of each time slot;

and the MAC unit determines the optical terminal connected with the first port corresponding to the first wavelength according to the detection result of each time slot.

In one possible design, the MAC unit is specifically configured to:

In a seventh aspect, an embodiment of the present application provides a system for determining an optical access network topology, including the apparatus of the second aspect or the apparatus of the fourth aspect or the apparatus of the sixth aspect, where the system further includes an optical distribution network ODN and a plurality of optical terminals, where the ODN is optically connected to the plurality of optical terminals, and the ODN includes an optical splitter or a plurality of optical splitters;

and an optical filter is deployed in a connection branch of the optical splitter in the ODN and each optical terminal in the plurality of optical terminals, wherein the optical filters on different connection branches correspond to different wavelengths and are used for reflecting or transmitting optical signals with different wavelengths.

In one possible design, a gain component is further disposed in a connection leg between the optical splitter and each of the plurality of optical terminals in the ODN, where the gain component is located between the optical splitter branching end and the optical filter, or between the optical filter and the optical terminal;

the gain component supports the generation of cross gain modulation effects or cross attenuation effects on multiple optical signals received simultaneously.

In one possible design, the optical filter is a bragg grating FBG.

Further combinations of the present application may be made to provide further implementations based on the implementations provided in the above aspects.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that are required to be used in the description of the embodiments will be briefly described below.

Fig. 1 is a schematic diagram of a system architecture according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a system configuration after modification of the system;

fig. 3A is a schematic diagram of a gain element deployment location according to an embodiment of the present application;

FIG. 3B is a schematic diagram of another gain element deployment location according to an embodiment of the present disclosure;

fig. 4 is a flow chart of a method for determining an optical access network topology according to a first possible implementation manner of the embodiment of the present application;

FIG. 5A is a schematic diagram illustrating a situation of detecting power variation of an optical signal according to a first possible implementation manner of the embodiments of the present application;

FIG. 5B is a schematic diagram illustrating another embodiment of the power variation of the detected optical signal according to the first possible implementation manner of the embodiment of the present application;

fig. 6 is a schematic diagram of an apparatus for determining an optical access network topology in a first possible implementation manner of an embodiment of the present application;

Fig. 7A is a schematic diagram illustrating determination of an optical access network topology according to an example one of embodiments of the present application;

fig. 7B is a schematic diagram illustrating determination of an optical access network topology according to example two of the embodiments of the present application;

fig. 8 is a flowchart of a method for determining an optical access network topology according to a second possible implementation manner of the embodiment of the present application;

fig. 9 is a schematic diagram of an apparatus for determining an optical access network topology in a second possible implementation manner of an embodiment of the present application;

fig. 10A is a schematic diagram illustrating determination of an optical access network topology according to example three of the present embodiment;

fig. 10B is a schematic diagram illustrating determination of another optical access network topology according to example three of the present embodiment;

fig. 10C is a schematic diagram illustrating determination of an optical access network topology according to example four of the present embodiment;

fig. 10D is a schematic diagram illustrating determination of another optical access network topology according to example four of the present embodiment;

fig. 10E is a schematic diagram illustrating determination of an optical access network topology according to an example fifth embodiment of the present application;

fig. 10F is a schematic diagram illustrating determination of another optical access network topology according to example five of the present embodiment;

fig. 10G is a schematic diagram illustrating determination of an optical access network topology according to an example six of the present embodiments;

Fig. 10H is a schematic diagram illustrating determination of another optical access network topology according to example six of the present embodiment;

fig. 11 is a flowchart of a method for determining an optical access network topology according to a third possible implementation manner of the embodiment of the present application;

fig. 12 is a schematic diagram of an apparatus for determining an optical access network topology in a third possible implementation manner of an embodiment of the present application;

fig. 13 is a schematic diagram illustrating determination of an optical access network topology according to an example seventh of the embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

Wherein, in the description of the present application, unless otherwise indicated, "a plurality" means two or more than two. In addition, "/" indicates that the associated object is an "or" relationship, e.g., A/B may represent A or B; the term "and/or" in this application is merely an association relation describing an association object, and means that three kinds of relations may exist, for example, a and/or B may mean: there are three cases, a alone, a and B together, and B alone, wherein a, B may be singular or plural. In addition, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the words "first", "second", and the like are used to distinguish the same item or similar items having substantially the same function and effect. It will be appreciated by those of skill in the art that the words "first," "second," and the like do not limit the amount and order of execution, and that the words "first," "second," and the like do not necessarily differ. It should also be noted that, unless specifically stated otherwise, a specific description of some features in one embodiment may also be applied to explaining other embodiments to mention corresponding features.

In the embodiments of the present application, words such as "exemplary" or "such as" are used to mean serving as examples, illustrations, or descriptions. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.

Referring to fig. 1, a schematic diagram of a system architecture according to an embodiment of the present application is shown. The system may be a passive optical network PON system 100. The PON system 100 may be applied to an optical access network. The PON system 100 comprises at least one optical line terminal OLT110, an optical distribution network ODN120 and a plurality of optical terminals. In fig. 1, an optical terminal is taken as an example of an ONT. The OLT110 in this application is connected to a plurality of ONTs 130 through an ODN 120. Wherein the direction from the OLT110 to the ONT130 is defined as the downstream direction, and the direction from the ONT130 to the OLT110 is the upstream direction.

The PON system 100 may be a communication network that does not require any active devices to enable data distribution between the OLT110 and the ONTs 130. For example, in a specific embodiment, the data distribution between the OLT110 and the ONTs 130 may be implemented by passive optical devices (such as optical splitters) in the ODN 120. Also, the PON system 100 may be an asynchronous transfer mode passive optical network (asynchronous transfer mode passive optical network, ATM PON) system or a broadband passive optical network (broadband passive optical network, BPON) system, a gigabit passive optical network (gigabit passive optical network, GPON) system, an ethernet passive optical network (ethernet passive optical network, EPON), or a next-generation passive optical network (next-generation passive optical network, NG PON), such as a 10gigabit passive optical network (10 gigabit-capable passive optical network, XG-PON) or a 10gigabit ethernet passive optical network (10Gigabit ethernet passive optical network,10GEPON or the like.

The OLT110 is typically located at a central location, such as a Central Office (CO), which may centrally manage one or more ONTs 130. The OLT110 may forward received downstream data to the ONTs 130 via the ODN120, and forward upstream data received from the ONTs 130.

The ONTs 130 may be located at a distributed location on the user side (e.g., a customer premises). The ONT130 may be a device for communicating with the OLT110 and a user, and in particular, the ONT130 may act between the OLT110 and the user.

For example, the ONT130 may forward downstream data received from the OLT110 to the user, and forward data received from the user as upstream data to the OLT110 through the ODN 120. It should be appreciated that the ONT130 is generally applicable to end users, such as light cats and the like; whereas ONUs may be applied to end users, they may be connected to end users via other networks, such as ethernet. In this application, the ONT130 is described as an example, and the ONT130 and the ONU may be interchanged.

ODN120 may include optical fibers, optical couplers, splitters, and/or other devices. In one embodiment, the optical fiber, optical coupler, optical splitter, and/or other device may be a passive optical device. That is, the optical fibers, optical couplers, splitters, and/or other devices may be devices that distribute data signals between the OLT110 and the ONTs 130 without power support. In addition, in other embodiments, the ODN120 may also include one or more active devices, such as optical amplifiers or Relay devices (Relay devices). In the branching structure shown in fig. 1, the ODN120 may specifically extend from the OLT110 to the plurality of ONTs 130 in a two-level optical splitting manner, but may be configured in any other point-to-multipoint (e.g., one-level optical splitting or multi-level optical splitting) or point-to-point structure. In the embodiment of the present application, two-level spectroscopy is taken as an example to describe, and the first-level spectroscopy and the multi-level spectroscopy (three-level and above spectroscopy) are similar, which is not limited in this application.

Referring to fig. 1, the ODN120 employs an optical splitter to implement data distribution, and for reliability and operation and maintenance, the ODN120 may be deployed in a two-stage optical splitting manner, including a first stage optical splitter 121 and a plurality of second stage optical splitters 122. The common end of the first stage optical splitter 121 is connected to the OLT110 through a trunk optical fiber, and the branch ends thereof are respectively and correspondingly connected to the common end of the second stage optical splitter 122 through distribution optical fibers, and the branch ends of each second stage optical splitter 122 are respectively and further connected to the upstream ports of the corresponding ONTs 130 through branch optical fibers. In the downstream direction, the downstream data signal sent by the OLT110 is first split by the first-stage splitter 121, and then split by the second-stage splitter 122 for the second time, so as to form multiple downstream optical signals, and the multiple downstream optical signals are transmitted to the ONTs 130. In the upstream direction, the upstream data signals transmitted from the ONTs 130 are sequentially combined by the second-stage optical splitter 122 and the first-stage optical splitter 121, and then transmitted to the OLT110.

For the deployment mode of the second-stage beam splitter, the second-stage beam splitter 122 is a final-stage beam splitter, and the first-stage beam splitter 121 is a previous-stage beam splitter connected with the final-stage beam splitter; for the deployment mode of the first-stage beam splitter, the first-stage beam splitter is the last-stage beam splitter; for the deployment mode of three-level light splitting, the third-level light splitter is a final-level light splitter, the second-level light splitter is a previous-level light splitter connected with the final-level light splitter, and the first-level light splitter is a previous-level light splitter connected with the second-level light splitter. From the above, the final stage beam splitter in this application refers to a beam splitter closer to the ONT.

Referring to fig. 1, the OLT110 is connected to the plurality of ONTs 130 through one or more optical splitters, and since the connection relationship is not always unchanged, the connection topology between the OLT110 and the plurality of ONTs in the ODN needs to be known in advance when the operation and maintenance personnel perform fault location and fault elimination. In one possible implementation, see fig. 2, a reflective or transmissive filter is added in the splitter, an absorption band (U-band) tunable laser is deployed in the CO, and a U-band receiver is added in the ONT.

And transmitting optical signals with different wavelengths through the U-band tunable laser, and then detecting whether the optical signals with the wavelengths are received by the ONT or not so as to determine the binding relation between the ONT and the ports of the optical splitter.

For example, a reflective filter is used in the ODN. The OLT firstly controls the U-band adjustable laser to send an optical signal with the wavelength lambda 1, and sends a message to request all ONTs to report whether the U-band optical signal is received or not. And then controlling the U-band adjustable laser to send an optical signal with the wavelength of lambda 9, and sending a message to request all ONTs to report whether the U-band optical signal is received or not. Based on the data reported twice by all ONTs, if a certain ONT does not receive the U-band optical signal twice, the ONT can be judged to be connected to the port 1 of the primary optical splitter and the port 1 of the secondary optical splitter. The port 1 of the primary optical splitter or the branch optical fiber of the port 1 is provided with a reflective filter with a wavelength lambda 1, and the reflective filter is used for reflecting an optical signal with the wavelength lambda 1. The branching optical fiber of the port 1 of the secondary optical splitter is provided with a reflection filter with a wavelength lambda 9 for reflecting the optical signal with the wavelength lambda 1. Different ports of different splitters correspond to reflection filters of different wavelengths. And so on, the binding relation between all ONTs and the optical splitter can be determined.

For another example, a transmissive filter is used in the ODN. The OLT firstly controls the U-band adjustable laser to send an optical signal with the wavelength lambda 1, and sends a message to request all ONTs to report whether the U-band optical signal is received or not. And then controlling the U-band adjustable laser to send an optical signal with the wavelength of lambda 9, and sending a message to request all ONTs to report whether the U-band optical signal is received or not. Based on the data reported twice by all ONTs, if one ONT receives the U-band optical signal twice, the ONT can be judged to be connected to the port 1 of the primary optical splitter and the port 1 of the secondary optical splitter. Wherein, the port 1 of the primary beam splitter or the branch optical fiber of the port 1 is provided with a transmission type filter at least for transmitting the optical signals with the wavelengths lambda 1 and lambda 9. The branching fiber of port 1 of the secondary splitter has a transmission filter for transmitting at least the optical signal of wavelength lambda 9. Different ports of different splitters correspond to transmission filters of different wavelengths or combinations of wavelengths. And so on, the binding relation between all ONTs and the optical splitter can be determined.

In the above manner, each device in the PON system needs to be modified to be implemented. The number of the optical terminals is large, and the transformation difficulty is high, so that the implementation complexity is increased.

Based on this, the embodiment of the application provides a method, a device and a system for determining an optical access network topology. When the problems of network connection failure, network signal difference and the like occur in the optical terminal, an operation and maintenance personnel can rapidly position the port connected with the optical terminal or the optical fiber link corresponding to the port according to the determined binding relation (or connection relation), and convenience is provided for fault positioning and fault elimination. And this application need not to reform transform optical terminal equipment, can reduce the realization complexity to reduce the wasting of resources that artifical reform transform leads to.

In PON upstream transmission, upstream data of different ONTs are transmitted upward in respective branch optical fibers, and the data are converged after passing through a splitter. The uplink adopts a time division multiplexing mode to transmit data, the uplink is divided into different time slots (slots), each ONT transmits data in which time slot, the OLT strictly performs unified scheduling and authorization, and the ONT can only respond passively. In one approach, bandwidth allocation is dynamic. The OLT is provided with a dynamic bandwidth allocation (dynamic bandwidth allocation, DBA) function. The OLT monitors the congestion of the PON in real time through the DBA module, and dynamically adjusts the bandwidth of the ONT according to the congestion, the current bandwidth utilization condition and the configuration condition. In another approach, a static bandwidth allocation (which may also be referred to as a fixed bandwidth allocation). The bandwidth occupied by each ONT is fixed, and the OLT may periodically allocate a grant of a fixed length of time to each ONT based on the bandwidth, delay, etc. of each ONT.

In the embodiment of the application, by utilizing the principle that different ONTs transmit optical signals in different time slots, different branches in the optical splitter correspond to different wavelengths, and the OLT transmits detection optical signals of different wavelengths, so that the change condition of the received optical signals is monitored in different time slots, and the binding relation between the optical terminal corresponding to the changed time slot and the port of the optical splitter branch corresponding to the wavelength is determined. The embodiment of the application mainly utilizes the cross modulation effect generated in the branch of the optical splitter by the detection optical signal and the uplink optical signal of the optical terminal to enable the optical signal received by the OLT to have variation.

Cross modulation refers to the modulation of the carrier wave of one signal on another signal by the interaction between signals in a nonlinear device, network or transmission coal. The cross modulation may be cross gain modulation or cross attenuation modulation.

In some embodiments, the optical filter and gain component are deployed by the connection leg of the optical splitter to the ONT. The optical filter may be a reflection type filter or a transmission type filter. For example, the optical filter may employ a fiber bragg grating (fiber bragg grating, FBG). For example, the gain element may employ an optical amplifier or other device having gain modulation functionality. In some scenarios, the functionality of the optical filter and the functionality of the gain component may be integrated into one component. For example, FBG doped optical fibers with reflection or transmission functions are adopted on the connecting channels of the optical splitter and the ONT. In other scenarios, the optical filter and gain component may be implemented by different components, and the optical filter may be deployed on a branch optical fiber. The gain element may be disposed on a branch-side (also referred to as a drop-side) fiber between the optical filter and the optical splitter or on a port of the optical splitter, as shown in fig. 3A. The gain element may also be located between the optical filter and the optical terminal, as shown in fig. 3B.

The present application illustratively provides three possible ways to determine topology information of an optical access network without requiring modification of the ONTs.

A first possible implementation: the optical filter disposed in the ODN may be a reflection type filter or a transmission type filter, i.e., a reflection type filter or a transmission type filter is disposed on a branch optical fiber of the optical splitter. And the optical head end continuously transmits the detection optical signals with specific wavelengths, and the optical head end controls a plurality of optical terminals in the optical access network to respectively transmit uplink optical signals on corresponding time slots. The optical signal of the ONT generates a cross gain modulation effect or a cross attenuation modulation effect on the reflected optical signal of the probe optical signal in the gain component of the branch, so that the optical head end detects that the power of the reflected optical signal of the probe optical signal is changed (e.g., increased or decreased) compared with the power of the probe optical signal. Since different optical filters correspond to different wavelengths or combinations of wavelengths, optical signals of different wavelengths or combinations of wavelengths can be reflected or transmitted. The optical filters with different wavelengths correspond to different ports, and then the optical head end can realize the binding of the ports of the optical splitter and the ONT according to the wavelength of the detected optical signal and the time of power change.

In a second possible implementation, the optical filter deployed in the ODN may be a reflective filter or a transmissive filter. And the optical head end controls a plurality of optical terminals in the optical access network to respectively send uplink optical signals on corresponding time slots. The optical signal for detection generates a cross gain modulation effect or a cross attenuation modulation effect on the uplink optical signal in the gain component of the branch, so that the power of the uplink optical signal of the optical terminal changes (e.g., increases or decreases). Since different optical filters correspond to different wavelengths or combinations of wavelengths, optical signals of different wavelengths or combinations of wavelengths can be reflected or transmitted. The optical filters with different wavelengths correspond to different ports, and then the optical head end can realize the binding of the ports of the optical splitter and the ONT according to the wavelength of the detection optical signal and the time slot of the uplink optical signal with power change.

In a third possible implementation, the optical filter deployed in the ODN may be a reflective filter or a transmissive filter. The pump light signal with specific wavelength is continuously sent at the optical head end. The pump light signal can be modulated by the setting information. Such as by frequency modulation of a set frequency or by pattern modulation of a set pattern. The set frequency may be, for example, a positive rate wave, but other frequencies may be used. The set pattern may be, for example, a spreading code. The optical head end controls a plurality of optical terminals in the optical access network to respectively send uplink optical signals on corresponding time slots. The detection optical signal generates a cross gain modulation effect or a cross attenuation modulation effect on the uplink optical signal in the gain component of the branch, so that the set frequency information or the set code type information in the pump optical signal is modulated on the uplink optical signal of the optical terminal, and further binding between the port of the optical splitter and the ONT can be realized based on the time slot where the uplink optical signal with the set frequency information or the set code type information is detected and the wavelength of the pump optical signal.

The three possible implementations are described in detail below with reference to the accompanying drawings.

A first possible implementation is described. Referring to fig. 4, a flowchart of a method for determining an optical access network topology according to a first possible implementation manner is shown. Take an example that the optical access network includes N optical terminals. The N optical terminals are in one-to-one optical connection with N ports included by a plurality of optical splitters in the optical access network. N is a positive integer. In some scenarios, an ODN in the optical access network employs a primary optical splitter, where the primary optical splitter includes at least N ports, and N optical terminals are optically connected to N ports in at least N ports in a one-to-one correspondence. In other scenarios, the ODN in the optical access network employs multiple stages of optical splitters, such as two stages, three stages, and so on. The plurality of final stage splitters in the ODN include at least N ports. For example, the number of the final stage optical splitters is 3, and then the total number of ports of the 3 final stage optical splitters is greater than or equal to N, and the N optical terminals are in one-to-one optical connection with the N ports of the 3 final stage optical splitters.

The method for determining the topology of the optical access network provided in fig. 4 specifically includes the following steps:

401, continuously transmitting a first wavelength detection optical signal, and controlling the plurality of optical terminals to respectively transmit uplink optical signals on time slots corresponding to each optical terminal.

The first wavelength corresponds to a first port of the optical splitter, and different ports of the optical splitter correspond to different wavelengths. The beam splitter may be a final stage beam splitter, a previous stage beam splitter, or a first stage beam splitter, which is not particularly limited in this application. Taking a two-stage optical splitter as an example, the first wavelength may correspond to port 1 of the first stage optical splitter or to port 1 of the second stage optical splitter.

The time slot corresponding to each optical terminal can be allocated to each optical terminal by adopting a DBA mode, and the uplink light-emitting time slot (called time slot for short) can also be allocated to each optical terminal by adopting a static bandwidth allocation mode.

And 402, detecting the power of the reflected optical signal of the detection optical signal in the optical signals received by the plurality of optical terminals respectively corresponding to the time slots.

In some embodiments, after the detected optical signal reaches the ODN, the detected optical signal passes through an optical filter disposed on a branch of a certain optical splitter, for example, the optical filter on the branch of the optical splitter has a function of reflecting the detected optical signal with the first wavelength, and the optical filter reflects the detected optical signal with the first wavelength back. The optical filters disposed on the branches of the other optical splitters of the same stage transmit out the detection optical signals of the first wavelength.

In other embodiments, after the detected optical signal reaches the ODN, the detected optical signal passes through an optical filter disposed on a branch of a splitter, for example, the optical filter on the branch of the splitter has a function of transmitting the detected optical signal with the first wavelength, and the optical filter transmits the detected optical signal with the first wavelength. The optical filters disposed on the branches of the other optical splitters of the same stage reflect back for the detection optical signal of the first wavelength.

403, determining the optical terminal connected to the first port corresponding to the first wavelength according to the relation between the time window in which the change of the power of the reflected optical signal of the detected optical signal is detected in the received optical signals and the time slots corresponding to the plurality of optical terminals.

Taking an optical terminal connected to the first port as an example of the first optical terminal. The time slot corresponding to the first optical terminal is a first time slot.

In the case of determining the optical terminal connected to the first port corresponding to the first wavelength according to the relationship between the time when the power of the reflected optical signal changes and the time slots respectively corresponding to the plurality of optical terminals, the following manner may be implemented: and when the time window for determining that the power of the reflected optical signal detected in the received optical signal is changed is located in a first time slot, determining that a first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength.

The method for determining an optical access network topology provided in fig. 4 may be implemented by the device for determining an optical access network topology. The device may be deployed at the head end, such as in the OLT. The device may also be deployed in a CO. Referring to fig. 6, the apparatus includes a medium access control (media access control, MAC) unit 510, a wavelength Tunable Laser (TL) 520, a photodetector 530, and a circulator 540. A first port of the circulator 540 is optically connected to the wavelength tunable laser 520, a second port of the circulator 540 is optically connected to the ODN, and a third port of the circulator 540 is optically connected to the photodetector 530. The wavelength tunable laser may also be referred to as a Tunable Laser (TL).

The MAC unit 510 may employ a field-programmable gate array (field-programmable gate array, FPGA), an application-specific integrated chip (application specific integrated circuit, ASIC), a system on chip (SoC), a central processing unit (central processor unit, CPU), a network processor (Network Processor, NP), a digital signal processing circuit (digital signal processor, DSP), a microcontroller (micro controller unit, MCU), a programmable controller (programmable logic device, PLD) or other integrated chips. The wavelength tunable laser 520 may emit detection light signals of various wavelengths. When identifying the branched branches (ports of the branches) to which the target ONT (any one of the ONTs connected by the ODN) is connected, the OLT may control the wavelength-tunable laser 520 to emit a plurality of wavelength detection optical signals, where the plurality of wavelength detection optical signals are wavelengths of the detection optical signals reflected or transmitted by the optical filter disposed on each branched branch. The photodetector 530 can detect the laser light reflected by the ODN, which is received by the circulator from the detection light signal emitted by the wavelength tunable laser 520.

In some embodiments, the MAC unit 510, the wavelength tunable laser 520, the photodetector 530, and the circulator 540 may be integrated into one chip or may be implemented by different chips. For example, the MAC unit 510 is implemented by one chip, such as a so-called MAC chip. The wavelength tunable laser 520, photodetector 530, and circulator 540 may be integrated in a chip, such as what is known as an OAI chip. In some scenarios, the MAC unit 510 is disposed in the OLT, and the wavelength tunable laser 520, the photodetector 530, and the circulator 540 are integrated in one chip, disposed outside the OLT, and optically connected to the OLT.

Taking an example of determining an optical terminal connected to a port of a branch of the optical splitter corresponding to the first wavelength.

The MAC unit 510 controls the plurality of optical terminals to transmit uplink optical signals on the time slots corresponding to each of the optical terminals, respectively. The wavelength tunable laser 520 continuously transmits the probe light signal of the first wavelength to the beam splitter through the circulator 540. The photodetector (photoelectric detector, PD) 530 can detect the power of the reflected optical signal of the probe optical signal from the optical signals received on the respective time slots through the circulator 540. Further, the MAC unit 510 determines, according to a relationship between a time window in which a change in power of a reflected optical signal is detected in a received optical signal and time slots corresponding to the plurality of optical terminals, an optical terminal to which the first port corresponding to the first wavelength is connected.

The relationship between the gain element and the optical filter is exemplified as the position shown in fig. 3A.

Example one:

the optical filters disposed on the branches of the optical splitter are all reflection filters. The optical terminal to which the first port is connected is a first optical terminal. The time slot corresponding to the first optical terminal is a first time slot. The optical filter disposed in the branch of the optical splitter to which the first optical terminal is connected has a function of reflecting the optical signal of the first wavelength. The optical filters disposed on the branches of the optical splitters connected to the other optical terminals have the function of transmitting the optical signals of the first wavelength. The optical filter in the connection branch of the optical splitter and the first optical terminal performs a reflection operation on the detected optical signal of the first wavelength, so as to reflect the detected optical signal of the first wavelength back. The optical filters on the branches corresponding to the ports of the optical splitters connected with the other optical terminals do not reflect the detection optical signals of the first wavelength, but directly transmit the detection optical signals. So that the reflected optical signal, i.e. the power, which is not detected in the optical signals received at the time slots corresponding to the other optical terminals does not fluctuate.

Specifically, the uplink optical signal of the first optical terminal generates a cross gain modulation effect or a cross attenuation modulation effect on the gain component of the connection branch for the detected optical signal, and for the optical signal obtained by reflecting the detected optical signal by the optical filter in the connection branch between the optical splitter and the first optical terminal, the gain component of the connection branch also generates a cross gain modulation effect or a cross attenuation modulation effect, so that the detected optical signal in the optical signal detected on the time slot of the first optical terminal is enhanced or weakened. The optical signals of the detection optical terminals are transmitted out when passing through the optical filters of the connecting branches of the optical splitters connected with the other optical terminals, namely, the reflected optical signals of the detection optical signals are not generated, so that the uplink optical signals of the other optical terminals also have no cross gain modulation effect or cross attenuation modulation effect on the reflected optical signals. So that the reflected light signal, i.e. the power of the reflected light signal, is not increased or decreased (approximately 0) on the time slots of the other optical terminals. Further, it may be determined that the power of the detected optical signal in the uplink optical signal received in the time slot of the first optical terminal fluctuates, such as increases or decreases, compared to the power of the detected optical signal in the uplink optical signal received in other time slots.

Referring to fig. 5A and 5B for example, the detected light signal power is denoted as P in fig. 5A and 5B _OAI The power of the detected optical signal detected in the received optical signal is expressed as P _{OAI_R} . The power of the detected optical signal in the uplink optical signal received in the time slot of the first optical terminal in fig. 5A is increased compared to the power of the detected optical signal in the uplink optical signal received in the other time slots. Fig. 5B shows the power of the detected probe optical signal in the uplink optical signal received in the time slot of the first optical terminal compared with the power received in the other time slotsThe power of the detected optical signal in the received uplink optical signal is increased. The uplink transmission of the optical terminal is completely controlled by the OLT DBA, and includes a transmission on time (Ton), an off time (Toff) and an on duration (i.e., a time slot occupied by the optical terminal) of an uplink optical signal of the optical terminal, and tc=toff-Ton.

In some embodiments, after determining the optical terminal to which the first port of the optical splitter is connected, determining the optical terminals to which the other ports are connected is continued. For example, the transmission of the probe optical signal of the second wavelength is continued, where the second wavelength corresponds to the second port of the optical splitter, and the optical terminal connected to the second port is determined by the method provided in the embodiment corresponding to fig. 4, and so on, until the optical terminals connected to all the ports are determined.

As an example, referring to fig. 7A, the optical access network includes 64 ONTs, respectively ONT1-ONT64. The ONTs 1-64 are connected to ports of different optical splitters, respectively. In fig. 7A, the MAC unit 510 is deployed in the OLT as an example. The OLT has other components, such as optical modules, etc., which are not shown in fig. 7A. Each branch of the optical splitter connected with the ONT is disposed with an optical filter. Gain components are also disposed on each leg of the splitter connection ONT. Gain components refer to components that cause two optical signals to produce an inter-gain modulation effect or an inter-attenuation modulation effect. The gain element may be a semiconductor optical amplifier or a doped optical fiber, for example. The different optical filters are reflective filters for reflecting optical signals of different wavelengths. The ports of the optical splitters to which the ONTs 1 to 64 are respectively connected are ports 1 to 64. The optical filters of the branches of ports 1-64 correspond to wavelengths λ1- λ64, respectively.

The wavelength tunable laser 520 is tuned to a wavelength λ1 and continuously emits a probe optical signal of the wavelength λ1. The power of the detection light signal is P _OAI . The probe optical signal of the wavelength lambda 1 is broadcast to the branches of the optical splitter. The probe optical signal of the wavelength λ1 is reflected back when passing through the optical filter of the branch of port 1. The probe optical signal at wavelength λ1 is transmitted directly through the optical filters of the branches of port 2-port 64.

The MAC unit 510 controls all the on-line ONTs in turn to transmit the upstream optical signals in a specific time slot. Different ONTs correspond to different time slots, and the time slots corresponding to ONTs 1-64 are time slots 1-64, respectively. When the ONT1 connected with the port 1 corresponding to the wavelength lambda 1 is turned to transmit the uplink optical signal, the uplink optical signal of the ONT1 generates a cross gain modulation effect or a cross attenuation modulation effect on the detected optical signal of the wavelength lambda 1 and the signal reflected by the optical filter of the detected optical signal of the wavelength lambda 1 when the uplink optical signal passes through the gain component. The photodetector 530 detects the power of the detection light signal from the received light signal, and can be understood as the power of the reflected light signal of the detection light signal.

The power of the detected optical signal detected by the photodetector 530 in time slot 1 may fluctuate (increase or decrease) compared to the power of the detected optical signals detected by other time slots. See, for example, fig. 7A. The dashed line in fig. 7A indicates the signal flow direction of the probe optical signal. The photodetector 530 may detect a time window in which power fluctuates. Further, the MAC unit 510 determines that the port 1 corresponding to the wavelength 1 is connected to the ONT1 according to the wavelength λ1 of the wavelength tunable laser, a time window in which the power fluctuates, and a time slot in which each ONT transmits an uplink optical signal, that is, a binding relationship exists.

Further, the MAC unit controls the wavelength tunable laser 520 to transmit the probe optical signal with the wavelength λ2, and continues to determine the optical terminal connected to the port 2 corresponding to the wavelength λ2.

Example two:

the optical filters disposed on the branches of the optical splitter are all transmissive filters. The optical terminal to which the first port is connected is a first optical terminal. The time slot corresponding to the first optical terminal is a first time slot. The optical filter disposed in the branch of the optical splitter to which the first optical terminal is connected has a function of transmitting an optical signal of a first wavelength and a function of reflecting optical signals of other wavelengths. The optical filters disposed in the branches of the optical splitters to which the other optical terminals are connected each have a function of reflecting an optical signal of the first wavelength. The optical filter in the connection branch of the optical splitter and the first optical terminal performs a transmission operation on the detected optical signal with the first wavelength, so as to transmit the detected optical signal with the first wavelength. The optical filters on the branches corresponding to the ports of the optical splitters to which the other optical terminals are connected reflect the detection optical signals of the first wavelength. Thus, the power of the detected optical signal in the optical signals received at the time slots corresponding to the other optical terminals is increased or reduced, while the reflected optical signal, i.e. the power of the detected optical signal not detected by the optical signal received at the time slot of the first optical terminal is not increased or reduced. So that the power of the detected optical signal detected in the optical signal received at the time slot of the first optical terminal fluctuates compared to the power of the detected optical signal detected in the optical signals received at the time slots of the other optical terminals.

Specifically, the uplink optical signals of the other optical terminals generate a cross gain modulation effect or a cross attenuation modulation effect on the gain component of the corresponding connection branch, and the optical signals obtained by reflecting the detection optical signals by the optical filters in the connection branch of the optical splitter and the first optical terminal also generate a cross gain modulation effect or a cross attenuation modulation effect on the gain component of the connection branch, so that the power of the detection optical signals detected in the optical signals received in the time slots corresponding to the other optical terminals is increased or reduced.

When the detection optical signal passes through the optical filter of the connection branch of the optical splitter connected with the first optical terminal, the detection optical signal is transmitted, namely, the reflected optical signal of the detection optical signal is not generated, so that the uplink optical signal of the first optical terminal also does not have cross gain modulation effect or cross attenuation modulation effect on the reflected optical signal. I.e. the reflected light signal of the probe light signal, which is not detected by the light signal received at the time slot of the first optical terminal, i.e. the power of the reflected light signal at the time slot of the first optical terminal is not increased or decreased. Further, it may be determined that the power of the detected optical signal in the uplink optical signal received in the time slot of the first optical terminal fluctuates, such as increases or decreases, compared to the power of the detected optical signal in the uplink optical signal received in other time slots.

As an example, see fig. 7B, the optical access network includes 64 ONTs, respectively ONT1-ONT64. The ONTs 1-64 are connected to ports of different optical splitters, respectively. In fig. 7B, the MAC unit 510 is deployed in the OLT as an example. The OLT has other components, such as optical modules, etc., which are not shown in fig. 7B. Each branch of the optical splitter connected with the ONT is disposed with an optical filter. Gain components are also disposed on each leg of the splitter connection ONT. Gain components refer to components that cause two optical signals to produce an inter-gain modulation effect or an inter-attenuation modulation effect. The gain element may be a semiconductor optical amplifier or a doped optical fiber, for example. The different optical filters are all transmission filters for transmitting optical signals of different wavelengths. The ports of the optical splitters to which the ONTs 1 to 64 are respectively connected are ports 1 to 64. The optical filters of the branches of ports 1-64 correspond to wavelengths λ1- λ64, respectively.

The wavelength tunable laser 520 is tuned to a wavelength λ1 and continuously emits a probe optical signal of the wavelength λ1. The power of the detection light signal is P _OAI . The probe optical signal of the wavelength lambda 1 is broadcast to the branches of the optical splitter. The probe optical signal of the wavelength λ1 is transmitted when passing through the optical filter of the branch of the port 1. The probe optical signal at wavelength λ1 is reflected back as it passes through the optical filters of the branches of port 2-port 64.

The MAC unit 510 controls all the on-line ONTs in turn to transmit the upstream optical signals in a specific time slot. Different ONTs correspond to different time slots, and the time slots corresponding to ONTs 1-64 are time slots 1-64, respectively. When the ONT1 connected to the port 1 corresponding to the wavelength λ1 is turned to transmit the uplink optical signal, the detection optical signal of the wavelength λ1 is transmitted when passing through the optical filter of the branch of the optical splitter corresponding to the ONT 1. When the other ONT2-ONT64 is turned to transmit the uplink optical signal, the uplink optical signal of the ONT2-ONT64 generates a cross gain modulation effect or a cross attenuation modulation effect on the detected optical signal with the wavelength λ1 and the reflected optical signal of the detected optical signal when passing through the gain component, so that the power of the detected optical signal in the optical signals detected on the time slots corresponding to the ONT2-ONT64 respectively increases or decreases. I.e. the power of the detected optical signals in the optical signals detected at the time slots corresponding to the ONT2-ONT64, respectively, are all approximately the same. And as the detected optical signal with the wavelength λ1 passes through the optical filter of the branch of the optical splitter corresponding to the ONT1, the power of the detected optical signal in the optical signal detected on the time slot corresponding to the ONT1 is not increased or reduced. The power of the detected optical signal detected by the photodetector 530 in time slot 1 may fluctuate (increase or decrease) compared to the power of the detected optical signals detected by other time slots. See, for example, fig. 7B. The dashed line in fig. 7B indicates the signal flow direction of the probe optical signal. The photodetector 530 may detect a time window in which power fluctuates. Further, the MAC unit 510 determines that the port 1 corresponding to the wavelength 1 is connected to the ONT1 according to the wavelength λ1 of the wavelength tunable laser, a time window in which the power fluctuates, and a time slot in which each ONT transmits an uplink optical signal, that is, a binding relationship exists.

A second possible implementation is described below. Referring to fig. 8, a flowchart of a method for determining an optical access network topology according to a second possible implementation manner is shown. Take an example that the optical access network includes N optical terminals. The N optical terminals are in one-to-one optical connection with N ports included by a plurality of optical splitters in the optical access network. N is a positive integer. In some scenarios, an ODN in the optical access network employs a primary optical splitter, where the primary optical splitter includes at least N ports, and N optical terminals are optically connected to N ports in at least N ports in a one-to-one correspondence. In other scenarios, the ODN in the optical access network employs multiple stages of optical splitters, such as two stages, three stages, and so on. The plurality of final stage splitters in the ODN include at least N ports. For example, the number of the final stage optical splitters is 3, and then the total number of ports of the 3 final stage optical splitters is greater than or equal to N, and the N optical terminals are in one-to-one optical connection with the N ports of the 3 final stage optical splitters.

The method for determining the topology of the optical access network provided in fig. 8 specifically includes the following steps:

801, continuously transmitting a pump optical signal of a first wavelength, and controlling the plurality of optical terminals to respectively transmit uplink optical signals on time slots corresponding to each optical terminal.

And 802, measuring the received power of the uplink optical signals received on the time slots corresponding to the plurality of optical terminals respectively.

In some embodiments, after the pump optical signal reaches the ODN, the pump optical signal passes through an optical filter disposed on a branch of a certain optical splitter, for example, the optical filter on the branch of the optical splitter has a function of reflecting the probe optical signal with the first wavelength, and the optical filter reflects the pump optical signal with the first wavelength back. The optical filters disposed on the branches of the other optical splitters of the same stage transmit out the detection optical signals of the first wavelength.

In other embodiments, after the pump optical signal reaches the ODN, the pump optical signal passes through an optical filter disposed on a branch of a splitter, for example, the optical filter on the branch of the splitter has a function of transmitting the pump optical signal with the first wavelength, and the optical filter transmits the probe optical signal with the first wavelength. The optical filters disposed on the branches of the other splitters of the same stage reflect back for the pump optical signal of the first wavelength.

803, determining, according to a change situation of the received power of each optical terminal in the plurality of optical terminals and the uplink baseline received power of each optical terminal, an optical terminal connected to the first port corresponding to the first wavelength.

The uplink baseline receiving power of one optical terminal is the receiving power of the uplink optical signal of the one optical terminal under the condition that the pump optical signal does not enter a connection branch between the optical splitter and the one optical terminal; the change of the receiving power of one optical terminal and the uplink baseline receiving power of the one optical terminal is generated by the cross gain modulation effect or the cross attenuation modulation effect generated by the pump optical signal on the uplink optical signal of the one optical terminal in the connection branch of the optical splitter and the first optical terminal.

Taking an optical terminal connected to the first port as an example of the first optical terminal. The time slot corresponding to the first optical terminal is a first time slot. In the case of determining, according to the change condition of the received power of each optical terminal in the plurality of optical terminals and the uplink baseline received power of each optical terminal, the optical terminal connected to the first port corresponding to the first wavelength, the following manner may be implemented:

when the difference between the power of the uplink optical signal received in the first time slot and the uplink baseline receiving power of the first optical terminal corresponding to the first time slot is greater than or equal to a set threshold value, and when the difference between the power of the uplink optical signal received in any time slot except the first time slot and the uplink baseline receiving power of the optical terminal corresponding to any time slot is less than the set threshold value, determining that the first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength; or,

For example, 64 ONTs, measure the received power of the uplink optical signal received on each slot. The difference between the measured received power for each slot and the uplink baseline received power for that slot is then measured. For example, uplink baseline received power passes P _rx And (3) representing. Measured received power passingAnd (3) representing. The received power difference corresponding to each slot is obtained. The reception power difference corresponding to slot i is by +.>And (3) representing. />The following formula (1) or formula (2) is satisfied.

Wherein,the received power of the uplink optical signal of the corresponding optical terminal is received in the slot i. />And the uplink baseline receiving power of the optical terminal corresponding to the time slot i is shown.

In some embodiments, when the cross modulation effect generated by the branches of the optical splitter is the cross gain modulation effect, the above formula (1) is used, and when the cross modulation effect generated by the branches of the optical splitter is the cross attenuation modulation effect, the above formula (2) is used.

In some embodiments, after determining the optical terminal to which the first port of the optical splitter is connected, determining the optical terminals to which the other ports are connected is continued. For example, the pump optical signal with the second wavelength is continuously sent, where the second wavelength corresponds to the second port of the optical splitter, and the optical terminal connected to the second port is determined by the method provided by the embodiment corresponding to fig. 8, and so on, until the optical terminals connected to all the ports are determined.

In some embodiments, before the pump optical signals of the first wavelength are continuously sent, the plurality of optical terminals are controlled to send uplink optical signals on time slots corresponding to each optical terminal respectively, and the received power of the uplink optical signals of the plurality of optical terminals is measured to obtain an uplink baseline received power of each optical terminal in the plurality of optical terminals. The calibration of the uplink baseline receiving power of each optical terminal can adopt the average value of a plurality of measurement results. It should be understood that, when measuring the uplink baseline receiving power, the pump optical signal does not enter the ODN, so as not to interfere with the calibration of the uplink baseline receiving power. For example, taking 64 ONTs as an example, one Trigger (Trigger) period is 5us, and the uplink baseline received power of each ONT may be an average of 10 measurements. The total time required is 64×5×10=3.2 ms.

In some scenarios, the laser on the optical terminal is an uncooled laser, and the emission power of the uncooled laser is susceptible to temperature variations. In order to avoid the influence of temperature factors, the time interval between calibrating the uplink baseline receiving power and triggering the optical terminal connected with the optical splitter port can be shortened. As an example, if the wavelength adjustment time of the wavelength tunable laser is 5s and the calibration time of the uplink baseline receiving power is 3.2ms, before the uplink baseline receiving power is calibrated and recorded, the wavelength tunable laser is controlled to start wavelength adjustment independently in advance, and it is ensured that the pump light signal does not enter the optical fiber during the calibration process of the uplink baseline receiving power, so as not to interfere with the calibration of the baseline receiving power.

The method for determining the topology of the optical access network provided in fig. 8 may be implemented by the device for determining the topology of the optical access network. The device may be deployed at the head end, such as in the OLT. Referring to fig. 9, the apparatus includes a medium access control (media access control, MAC) unit 910, a wavelength Tunable Laser (TL) 920, and a power measurer 930.

The MAC unit 910 may employ an FPGA, an ASIC), a SoC), a CPU, an NP, a DSP, an MCU, a PLD, or other integrated chip. The wavelength tunable laser 920 may emit pump light signals of various wavelengths. When identifying the branch (port of the branch) to which the target ONT (any one of the ODN connection) is connected, the OLT may control the wavelength-tunable laser 920 to emit pump optical signals with multiple wavelengths, where the pump optical signals with multiple wavelengths are wavelengths of the pump optical signals reflected by the optical filter disposed on each branch.

The power measurer may be an optical module 930, and may also be a received signal strength indicator (Received Signal Strength Indicator, RSSI). The optical module 930 is taken as an example in the following, and the optical module 930 is taken as an example in fig. 9. In some embodiments, the MAC unit 910, TL920, and optical module 930 may all be integrated in one chip or may be implemented by different chips.

The MAC unit 910 controls a plurality of optical terminals to transmit uplink optical signals on time slots corresponding to each optical terminal, respectively. The wavelength tunable laser 920 continuously transmits the pump light signal of the first wavelength to the optical splitter. And an optical module 930, configured to measure the received power of the uplink optical signals received at the timeslots corresponding to the plurality of optical terminals.

The MAC unit 910 determines, according to a change condition of the received power of each optical terminal in the plurality of optical terminals compared to the uplink baseline received power of each optical terminal, an optical terminal connected to the first port corresponding to the first wavelength.

Example three:

the optical filters disposed on the branches of the optical splitter are all reflection filters. The optical terminal to which the first port is connected is a first optical terminal. The time slot corresponding to the first optical terminal is a first time slot. The optical filter disposed in the branch of the optical splitter to which the first optical terminal is connected has a function of reflecting the optical signal of the first wavelength. The optical filters disposed on the branches of the optical splitters connected to the other optical terminals have the function of transmitting the optical signals of the first wavelength.

Referring to fig. 10A, an optical filter in a connection branch of the optical splitter and the first optical terminal performs a reflection operation on a pump optical signal with a first wavelength, so that the pump optical signal with the first wavelength is reflected back, and thus, both the pump optical signal with the first wavelength and an optical signal generated by reflecting the pump optical signal with the optical filter generate a cross modulation effect on an uplink optical signal of the first optical terminal in the gain component. The optical filters on the branches corresponding to the ports of the optical splitters connected with the other optical terminals do not reflect the pump optical signals with the first wavelength, but directly transmit the pump optical signals with the first wavelength. Therefore, only the pump optical signal with the first wavelength generates a cross modulation effect on the uplink optical signal of the first optical terminal, and the reflected optical signal does not generate the cross modulation effect on the uplink optical signal. Therefore, the power variation amplitude of the uplink optical signal caused by the pump optical signal on the uplink optical signal received on the time slot corresponding to other optical terminals is small. The pump optical signal with the first wavelength and the optical signal generated by reflecting the pump optical signal by the optical filter both generate a cross modulation effect on the uplink optical signal of the first optical terminal in the gain component, so that the change amplitude of the receiving power of the uplink optical signal of the first optical terminal is larger.

Based on the above, only the received power of the uplink optical signal of the first optical terminal has a larger variation range than the baseline received power, that is, it is determined that the received power of the uplink optical signal detected by the first time slot has a larger variation range than the baseline received power of the optical terminal corresponding to the first time slot, so that it is determined that the first optical terminal corresponding to the first time slot has a binding relationship with the branch end of the optical splitter corresponding to the first wavelength.

As an example, referring to fig. 10B, a method for determining an optical access network topology according to an embodiment of the present application will be described with reference to fig. 9. The optical access network includes 64 ONTs, respectively, for example, ONT1-ONT 64. The ONTs 1-64 are connected to ports of different optical splitters, respectively. Each branch of the optical splitter connected with the ONT is disposed with an optical filter. Gain components are also disposed on each leg of the splitter connection ONT. Gain components refer to components that cause two optical signals to produce an inter-gain modulation effect or an inter-attenuation modulation effect. The gain element may be a semiconductor optical amplifier or a doped optical fiber, for example. Different optical filters are used to reflect optical signals of different wavelengths or combinations of wavelengths. The ports of the optical splitters to which the ONTs 1 to 64 are respectively connected are ports 1 to 64. The optical filters of the branches of ports 1-64 correspond to wavelengths λ1- λ64, respectively.

The wavelength tunable laser 920 is tuned to a wavelength λ1 and continuously emits a pump light signal of the wavelength λ1. The pump light signal of the wavelength lambda 1 is broadcast to the branches of the splitter. The pump light signal of the wavelength λ1 is reflected back when passing through the optical filter of the branch of port 1. The pump light signal at wavelength λ1 is transmitted directly out through the optical filter of the branch of port 2-port 64.

The MAC unit 910 controls all the on-line ONTs in turn to transmit the upstream optical signals in a specific time slot. Different ONTs correspond to different time slots, and the time slots corresponding to ONTs 1-64 are time slots 1-64, respectively. When the optical network unit turns to the ONT1 connected with the port 1 corresponding to the wavelength lambda 1 to transmit the uplink optical signal, the reflected optical signal of the pump optical signal with the wavelength lambda 1 generates a cross gain modulation effect or a cross attenuation modulation effect on the uplink optical signal of the ONT1 when passing through the gain component. The optical module 930 measures the received power of the uplink optical signals received in the time slots 1 to 64, respectively. The MAC unit 910 compares the received power difference between the received power of the uplink optical signal measured at each slot and the uplink baseline received power of the optical terminal corresponding to the slot. The MAC unit 910 compares the received power difference value of each slot with a set threshold. The MAC unit 910 determines that the difference between the received power of the uplink optical signal received in the slot 1 and the uplink baseline received power of the optical terminal corresponding to the slot 1 is greater than or equal to the set threshold. Further, the MAC unit 910 determines, according to the wavelength λ1 of the wavelength tunable laser and the optical terminal corresponding to the received power difference, that the port 1 corresponding to the wavelength 1 is connected to the ONT1, that is, there is a binding relationship.

Further, the MAC unit 910 controls the wavelength tunable laser 920 to transmit the pump optical signal with the wavelength λ2, and continues to determine the optical terminal connected to the port 2 corresponding to the wavelength λ2. And so on.

Example four:

the optical filters disposed on the branches of the optical splitter are all transmissive filters. The optical terminal to which the first port is connected is a first optical terminal. The time slot corresponding to the first optical terminal is a first time slot. The optical filter disposed in the branch of the optical splitter to which the first optical terminal is connected has a function of transmitting an optical signal of a first wavelength. The optical filters disposed in the branches of the optical splitters to which the other optical terminals are connected each have a function of reflecting an optical signal of the first wavelength.

Referring to fig. 10C, the optical filter in the connection branch of the optical splitter and the first optical terminal performs a transmission operation on the pump optical signal with the first wavelength, so that the pump optical signal with the first wavelength is transmitted, and only the pump optical signal with the first wavelength generates a cross modulation effect on the uplink optical signal of the first optical terminal in the gain component, and no cross modulation effect on the uplink optical signal by the reflected optical signal exists. Therefore, the power variation amplitude of the uplink optical signal caused by the pump optical signal by the uplink optical signal received on the time slot corresponding to the first optical terminal is smaller. The pump optical signal of the first wavelength is reflected by the optical filter on the branch corresponding to the port of the optical splitter to which the other optical terminal is connected. Thus, the pump optical signal of the first wavelength and the reflected optical signal of the pump optical signal have a cross modulation effect on the upstream optical signals of other optical terminals. Therefore, the uplink optical signals received on the time slots corresponding to other optical terminals cause larger power variation amplitude of the uplink optical signals due to the pumping optical signals and the reflected optical signals.

Based on the above, only the received power of the uplink optical signal of the first optical terminal is smaller than the baseline received power variation amplitude, that is, the received power of the uplink optical signal detected by the first time slot is determined to be smaller than the baseline received power variation amplitude of the optical terminal corresponding to the first time slot, and the received power of the uplink optical signal detected by other time slots is determined to be larger than the baseline received power variation amplitude of the optical terminal corresponding to other time slots, so that the first optical terminal corresponding to the first time slot and the branch end of the optical splitter corresponding to the first wavelength have a binding relation.

As an example, referring to fig. 10D, a method for determining an optical access network topology according to an embodiment of the present application will be described with reference to fig. 9. The optical access network includes 64 ONTs, respectively, for example, ONT1-ONT 64. The ONTs 1-64 are connected to ports of different optical splitters, respectively. Each branch of the optical splitter connected with the ONT is arranged on the optical filter and is a transmission type filter. Gain components are also disposed on each leg of the splitter connection ONT. The ports of the optical splitters to which the ONTs 1 to 64 are respectively connected are ports 1 to 64. The optical filters of the branches of ports 1-64 correspond to wavelengths λ1- λ64, respectively.

The wavelength tunable laser 920 is tuned to a wavelength λ1 and continuously emits a pump light signal of the wavelength λ1. The pump light signal of the wavelength lambda 1 is broadcast to the branches of the splitter. The pump light signal of the wavelength λ1 is transmitted when passing through the optical filter of the branch of port 1. The pump optical signal at wavelength λ1 is reflected back as it passes through the optical filters of the branches of port 2-port 64.

The MAC unit 910 controls all the on-line ONTs in turn to transmit the upstream optical signals in a specific time slot. Different ONTs correspond to different time slots, and the time slots corresponding to ONTs 1-64 are time slots 1-64, respectively. When the ONT1 connected with the port 1 corresponding to the wavelength lambda 1 is rotated to transmit the uplink optical signal, the pump optical signal with the wavelength lambda 1 generates a cross gain modulation effect or a cross attenuation modulation effect on the uplink optical signal of the ONT1 when the pump optical signal with the wavelength lambda 1 only passes through the gain component. So that the power of the uplink optical signal of the ONT1 is smaller than the baseline received power variation amplitude of the ONT 1. When any one of the ONTs 2-64 connected to the port 2-64 transmits an upstream optical signal, the pump optical signal with the wavelength λ1 and the reflected optical signal of the pump optical signal will both generate a cross gain modulation effect or a cross attenuation modulation effect on the upstream optical signal of any one of the ONTs 2-64 when the gain component meets the upstream optical signal of any one of the ONTs 2-64. The received power of the uplink optical signal of any one of the ONTs 2-64 is enabled to be larger in variation amplitude compared with the baseline received power of the any one ONT.

The optical module 930 measures the received power of the uplink optical signals received in the time slots 1 to 64, respectively. The MAC unit 910 compares the received power difference between the received power of the uplink optical signal measured at each slot and the uplink baseline received power of the optical terminal corresponding to the slot. The MAC unit 910 compares the received power difference value of each slot with a set threshold.

The MAC unit 910 determines that the difference between the received power of the uplink optical signal received by the slot 1 and the uplink baseline received power of the optical terminal corresponding to the slot 1 is smaller than the set threshold, and the MAC unit 910 determines that the difference between the received power of the uplink optical signal received by the slot 2-slot 64 and the uplink baseline received power of the optical terminal corresponding to the slots respectively corresponding to the slots is greater than or equal to the set threshold. Further, the MAC unit 910 determines, according to the wavelength λ1 of the wavelength tunable laser and the optical terminal corresponding to the received power difference, that the port 1 corresponding to the wavelength 1 is connected to the ONT1, that is, there is a binding relationship.

The relationship between the gain element and the optical filter is exemplified as the position shown in fig. 3B.

Example five:

Referring to fig. 10E, the optical filter in the connection branch of the optical splitter and the first optical terminal performs a reflection operation on the pump optical signal with the first wavelength, so that the pump optical signal with the first wavelength is reflected back, and thus the pump optical signal with the first wavelength does not reach the gain component, that is, does not generate a cross modulation effect on the upstream optical signal of the first optical terminal in the gain component. The optical filters on the branches corresponding to the ports of the optical splitters connected to the other optical terminals do not reflect the pump optical signals of the first wavelength, but directly transmit the pump optical signals of the first wavelength to pass through the gain component. So that the pump optical signal of the first wavelength produces a cross modulation effect in the gain component on the upstream optical signals of the other optical terminals. The uplink optical signals received at the time slots corresponding to other optical terminals cause power variation of the uplink optical signals due to the pump optical signals. The pump optical signal with the first wavelength does not generate a cross modulation effect on the uplink optical signal of the first optical terminal in the gain component, so that the receiving power of the uplink optical signal of the first optical terminal cannot be changed.

Based on the above, only the received power of the uplink optical signal of the first optical terminal is unchanged from the baseline received power, and the received powers of the uplink optical signals of other optical terminals are changed from the baseline received power, that is, it is determined that the received power of the uplink optical signal detected by the first time slot is unchanged from the baseline received power of the optical terminal corresponding to the first time slot, so as to determine that the first optical terminal corresponding to the first time slot has a binding relationship with the branch end of the optical splitter corresponding to the first wavelength.

As an example, referring to fig. 10F, a method for determining an optical access network topology provided in an embodiment of the present application will be described with reference to the determining apparatus provided in fig. 9. The optical access network includes 64 ONTs, respectively, for example, ONT1-ONT 64. The ONTs 1-64 are connected to ports of different optical splitters, respectively. Each branch of the optical splitter connected with the ONT is arranged on the optical filter and is a reflection type filter. Gain components are also disposed on each leg of the splitter connection ONT. The ports of the optical splitters to which the ONTs 1 to 64 are respectively connected are ports 1 to 64. The optical filters of the branches of ports 1-64 correspond to wavelengths λ1- λ64, respectively.

The wavelength tunable laser 920 is tuned to a wavelength λ1 and continuously emits a pump light signal of the wavelength λ1. The pump light signal of the wavelength lambda 1 is broadcast to the branches of the splitter. The pump light signal of the wavelength λ1 is reflected back when passing through the optical filter of the branch of the port 1, and does not reach the gain element of the port 1. The pump optical signal at wavelength λ1, when passing through the optical filter of the branch of port 2-port 64, is transmitted out to reach the gain element of the branch of port 2-port 64.

The MAC unit 910 controls all the on-line ONTs in turn to transmit the upstream optical signals in a specific time slot. Different ONTs correspond to different time slots, and the time slots corresponding to ONTs 1-64 are time slots 1-64, respectively. When the ONT1 connected with the port 1 corresponding to the wavelength lambda 1 is used for transmitting the uplink optical signal, the cross gain modulation effect or the cross attenuation modulation effect can not be generated on the uplink optical signal of the ONT1 when the pump optical signal of the wavelength lambda 1 does not pass through the gain component. So that the power of the upstream optical signal of the ONT1 is unchanged from the baseline received power of the ONT 1. When any one of the ONTs 2-64 connected to the port 2-64 is rotated to transmit an uplink optical signal, the pump optical signal with the wavelength λ1 will meet the uplink optical signal of any one of the ONTs 2-64 in the gain component after passing through the optical filter, and the pump optical signal with the wavelength λ1 will generate a cross gain modulation effect or a cross attenuation modulation effect on the uplink optical signal of any one of the ONTs 2-64. So that the received power of the upstream optical signal of any one of the ONTs 2-64 is changed from the baseline received power of that any one of the ONTs.

MAC unit 910 determines that the difference between the received power of the uplink optical signal received in slot 1 and the uplink baseline received power of the optical terminal corresponding to slot 1 is smaller than the set threshold (approximately 0), and MAC unit 910 determines that the difference between the received power of the uplink optical signal received in slot 2-slot 64 and the uplink baseline received power of the optical terminal corresponding to the respective corresponding slots is greater than or equal to the set threshold. Further, the MAC unit 910 determines, according to the wavelength λ1 of the wavelength tunable laser and the optical terminal with the received power difference smaller than the set threshold, that the port 1 corresponding to the wavelength 1 is connected to the ONT1, that is, there is a binding relationship.

Example six:

Referring to fig. 10G, the optical filter in the connection branch of the optical splitter and the other optical terminals performs a reflection operation on the pump optical signal with the first wavelength, so that the pump optical signal with the first wavelength is reflected back, and thus the pump optical signal with the first wavelength does not reach the gain component, that is, does not generate a cross modulation effect on the uplink optical signals of the other optical terminals in the gain component. The pump optical signals with the first wavelength do not generate cross modulation effect on the uplink optical signals of other optical terminals in the gain component, so that the receiving power of the uplink optical signals of other optical terminals is not changed. The optical filter on the branch corresponding to the port of the optical splitter connected to the first optical terminal does not reflect the pump optical signal of the first wavelength, but directly transmits the pump optical signal out and passes through the gain component. The pump optical signal of the first wavelength thus produces a cross modulation effect in the gain component on the upstream optical signal of the first optical terminal. The uplink optical signal received at the first time slot corresponding to the first optical terminal causes power variation of the uplink optical signal due to the pumping optical signal.

Based on this, only the received power of the uplink optical signal of the first optical terminal changes from the baseline received power, but the received powers of the uplink optical signals of other optical terminals do not change from the baseline received power, that is, it is determined that the received power of the uplink optical signal detected by the first time slot changes from the baseline received power of the optical terminal corresponding to the first time slot, so as to determine that the first optical terminal corresponding to the first time slot has a binding relationship with the branch end of the optical splitter corresponding to the first wavelength.

As an example, referring to fig. 10H, a method for determining an optical access network topology provided in an embodiment of the present application will be described with reference to the determining apparatus provided in fig. 9. The optical access network includes 64 ONTs, respectively, for example, ONT1-ONT 64. The ONTs 1-64 are connected to ports of different optical splitters, respectively. Each branch of the optical splitter connected with the ONT is arranged on the optical filter and is a transmission type filter. Gain components are also disposed on each leg of the splitter connection ONT. The ports of the optical splitters to which the ONTs 1 to 64 are respectively connected are ports 1 to 64. The optical filters of the branches of ports 1-64 correspond to wavelengths λ1- λ64, respectively.

The wavelength tunable laser 920 is tuned to a wavelength λ1 and continuously emits a pump light signal of the wavelength λ1. The pump light signal of the wavelength lambda 1 is broadcast to the branches of the splitter. The pump light signal with the wavelength λ1 is transmitted through the optical filter of the branch of the port 1, and reaches the gain component of the port 1. The pump optical signal at wavelength λ1, when passing through the optical filter of the branch of port 2-port 64, is reflected back without reaching the gain element of the branch of port 2-port 64.

The MAC unit 910 controls all the on-line ONTs in turn to transmit the upstream optical signals in a specific time slot. Different ONTs correspond to different time slots, and the time slots corresponding to ONTs 1-64 are time slots 1-64, respectively. When the ONT1 connected to the port 1 corresponding to the wavelength λ1 is turned to transmit the uplink optical signal, the cross gain modulation effect or the cross attenuation modulation effect is generated on the uplink optical signal of the ONT1 when the pump optical signal of the wavelength λ1 passes through the gain component. So that the power of the upstream optical signal of the ONT1 is changed from the baseline received power of the ONT 1. When any one of the ONTs 2-64 connected to the port 2-64 transmits an upstream optical signal, the pump optical signal with the wavelength λ1 is reflected back through the optical filter to the gain component, so that the pump optical signal with the wavelength λ1 does not meet the upstream optical signal of any one of the ONTs 2-64 in the gain component, and the pump optical signal with the wavelength λ1 does not generate a cross gain modulation effect or a cross attenuation modulation effect on the upstream optical signal of any one of the ONTs 2-64. So that the received power of the upstream optical signal of any one of the ONTs 2-64 will not change.

MAC unit 910 determines that the difference between the received power of the uplink optical signal received in slot 1 and the uplink baseline received power of the optical terminal corresponding to slot 1 is greater than or equal to a set threshold, and MAC unit 910 determines that the difference between the received power of the uplink optical signal received in slot 2-slot 64 and the uplink baseline received power of the optical terminal corresponding to the respective corresponding slots is less than the set threshold ((approximately 0)). Further, the MAC unit 910 determines, according to the wavelength λ1 of the wavelength tunable laser and the optical terminal having the received power difference greater than or equal to the set threshold, that the port 1 corresponding to the wavelength 1 is connected to the ONT1, that is, a binding relationship exists.

A third possible implementation is described below. Referring to fig. 11, a flowchart of a method for determining an optical access network topology according to a third possible implementation manner is shown. Take an example that the optical access network includes N optical terminals. The N optical terminals are in one-to-one optical connection with N ports included by a plurality of optical splitters in the optical access network. N is a positive integer. In some scenarios, an ODN in the optical access network employs a primary optical splitter, where the primary optical splitter includes at least N ports, and N optical terminals are optically connected to N ports in at least N ports in a one-to-one correspondence. In other scenarios, the ODN in the optical access network employs multiple stages of optical splitters, such as two stages, three stages, and so on. The plurality of final stage splitters in the ODN include at least N ports. For example, the number of the final stage optical splitters is 3, and then the total number of ports of the 3 final stage optical splitters is greater than or equal to N, and the N optical terminals are in one-to-one optical connection with the N ports of the 3 final stage optical splitters.

The method for determining the topology of the optical access network provided in fig. 11 specifically includes the following steps:

1101, continuously transmitting a pump optical signal of a first wavelength, and controlling the plurality of optical terminals to transmit an uplink optical signal on a time slot corresponding to each optical terminal.

The pump light signal is modulated with setting information. The setting information may be setting frequency information or setting a pattern.

1102, measuring the received power of the uplink optical signals received in the time slots corresponding to the plurality of optical terminals, and/or detecting the setting information from the uplink optical signals received in the time slots corresponding to the plurality of optical terminals to obtain a detection result of each time slot.

1103, determining, according to a detection result, an optical terminal connected to the first port corresponding to the first wavelength.

The measured change of the received power of the optical terminal compared with the uplink baseline received power of the optical terminal is generated by the cross gain modulation effect or the cross attenuation modulation effect generated by the pump optical signal on the uplink optical signal of the optical terminal in the connection branch of the optical splitter and the first optical terminal.

The received setting information of the uplink optical signal of one optical terminal is: the pump optical signal generates a cross gain modulation effect or a cross attenuation modulation effect on the uplink optical signal of the optical terminal in the connecting branch circuit of the optical splitter and the first optical terminal, so that the setting information carried by the pump optical signal is modulated to the uplink optical signal of the optical terminal to generate the cross gain modulation effect or the cross attenuation modulation effect.

The determining, according to the detection result, the optical terminal connected to the first port corresponding to the first wavelength may be implemented in any one of the following manners:

mode 1: and when the difference between the power of the uplink optical signal received in the first time slot and the uplink baseline receiving power of the first optical terminal corresponding to the first time slot is larger than or equal to a set threshold value and the difference between the power of the uplink optical signal received in other time slots and the uplink baseline receiving power of the optical terminal corresponding to other time slots is smaller than the set threshold value, determining that the first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength.

Mode 2: when the received uplink optical signal in the first time slot detects the setting information, the first optical terminal corresponding to the first time slot is determined to be optically connected with the first port corresponding to the first wavelength.

Mode 3: and when the set information is detected in the uplink optical signals received in the first time slot, determining that a first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength.

Mode 4: and when the difference between the power of the uplink optical signal received by each time slot in the plurality of time slots corresponding to the plurality of optical terminals and the uplink baseline receiving power of the optical terminal corresponding to each time slot is larger than a set threshold value and the set information is detected in the uplink optical signal received in the first time slot, determining that the first optical terminal corresponding to the first time slot is optically connected with the first port corresponding to the first wavelength.

The difference between the power of the uplink optical signal received in each of the plurality of time slots corresponding to the plurality of optical terminals and the uplink baseline received power of the optical terminal corresponding to each of the time slots satisfies the condition of the above formula (1) and formula (2).

The third possible manner is similar to the optical path transmission principle in the second possible manner, and will not be described here. It can be understood that in the case where the pump optical signal reaches the gain component to generate a cross modulation effect on the upstream optical signal of a certain optical terminal, the setting information in the pump optical signal is modulated into the upstream optical signal of the optical terminal. And in the case of no cross modulation effect, the signal is not modulated into the uplink optical signal of the optical terminal. Therefore, the binding relation between the optical terminal and the branch port of the optical splitter can be determined according to the detection condition of the setting information.

In some embodiments, before the pump optical signal of the first wavelength is continuously sent, calibration of the uplink baseline receiving power of each optical terminal is performed, which is specifically referred to as related description in the second possible implementation manner, and is not repeated herein.

The method for determining an optical access network topology provided in fig. 11 may be implemented by the device for determining an optical access network topology. The device may be deployed at the head end, such as in the OLT. Referring to fig. 12, the apparatus includes MAC units 1210 and TL 1220 and a signal detector 1230.

The MAC unit 1210 may be an FPGA, an ASIC, a SoC, a CPU, an NP, a DSP, an MCU, a PLD, or other integrated chips. The wavelength tunable laser 1220 may emit pump light signals of various wavelengths. When identifying the branch (port of the branch) to which the target ONT (any one of the ODN connection) is connected, the OLT may control the wavelength-tunable laser 1220 to emit pump optical signals with multiple wavelengths, where the pump optical signals with multiple wavelengths are wavelengths of the pump optical signals reflected by the optical filter disposed on each branch.

The signal detector may be an optical module 1230, or a receiver. The signal detector has a received signal strength indicator (Received Signal Strength Indicator, RSSI) detection function and a correlation detection function for setting a frequency or setting a pattern. The signal detector is taken as an example of the optical module 1230 in the following. In some embodiments, the MAC unit 1210, TL1220 and optical module 1230 may be integrated into one chip or may be implemented by different chips.

The MAC unit 1210 controls a plurality of optical terminals to transmit uplink optical signals on time slots corresponding to each optical terminal, respectively. The wavelength tunable laser 1220 continuously transmits a pump light signal of a first wavelength modulated with setting information to the optical splitter. The optical module 1230 is configured to measure the received power of the uplink optical signals received in the time slots corresponding to the plurality of optical terminals, and detect specific information from the uplink optical signals received in the time slots corresponding to the plurality of optical terminals, to obtain a detection result.

The MAC unit 1210 determines, according to the detection result, an optical terminal to which the first port corresponding to the first wavelength is connected.

Example seven:

Referring to fig. 13, an optical access network includes 64 ONTs, respectively, ONT1-ONT 64. The ONTs 1-64 are connected to ports of different optical splitters, respectively. In fig. 13, the signal detector 1230 is an optical module 1230 as an example. Each branch of the optical splitter connected with the ONT is arranged on the optical filter and is a reflection type filter. Gain components are also disposed on each leg of the splitter connection ONT. Gain components refer to components that cause two optical signals to produce an inter-gain modulation effect or an inter-attenuation modulation effect. The gain element may be a semiconductor optical amplifier or a doped optical fiber, for example. Different optical filters are used to reflect optical signals of different wavelengths or combinations of wavelengths. The ports of the optical splitters to which the ONTs 1 to 64 are respectively connected are ports 1 to 64. The optical filters of the branches of ports 1-64 correspond to wavelengths λ1- λ64, respectively.

The wavelength tunable laser 1220 is tuned to a wavelength λ1 and continuously emits a pump light signal of the wavelength λ1. The pump light signal of the wavelength lambda 1 is broadcast to the branches of the splitter. The pump light signal of the wavelength λ1 is reflected back when passing through the optical filter of the branch of the port 1, and does not reach the gain element of the port 1. The pump optical signal at wavelength λ1, when passing through the optical filter of the branch of port 2-port 64, is transmitted out to reach the gain element of the branch of port 2-port 64.

The MAC unit 1210 controls all the on-line ONTs in turn to transmit the uplink optical signal in a specific time slot. Different ONTs correspond to different time slots, and the time slots corresponding to ONTs 1-64 are time slots 1-64, respectively. When the ONT1 connected with the port 1 corresponding to the wavelength lambda 1 is used for transmitting the uplink optical signal, the cross gain modulation effect or the cross attenuation modulation effect can not be generated on the uplink optical signal of the ONT1 when the pump optical signal of the wavelength lambda 1 does not pass through the gain component. The power of the uplink optical signal of the ONT1 is unchanged from the baseline receiving power of the ONT1, and the setting information is not modulated in the uplink optical signal. When any one of the ONTs 2-64 connected to the port 2-64 is rotated to transmit an uplink optical signal, the pump optical signal with the wavelength λ1 will meet the uplink optical signal of any one of the ONTs 2-64 in the gain component after passing through the optical filter, and the pump optical signal with the wavelength λ1 will generate a cross gain modulation effect or a cross attenuation modulation effect on the uplink optical signal of any one of the ONTs 2-64. The received power of the upstream optical signal of any one of the ONTs 2-64 is changed from the baseline received power of the any one of the ONTs, and the upstream optical signal of any one of the ONTs 2-64 is modulated with the setting information.

The optical module 1230 measures the received power of the uplink optical signals respectively received from the time slots 1 to 64 and the uplink optical signal detection setting information respectively received from the time slots 1 to 64. The MAC unit 1210 compares the received power difference between the received power of the uplink optical signal measured at each slot and the uplink baseline received power of the optical terminal corresponding to the slot. The MAC unit 1210 obtains a comparison result of the received power difference value and the set threshold value for each slot and/or a slot in which the uplink optical signal including the set information is located. For example, the MAC unit 1210 determines that the difference between the received power of the uplink optical signal received in the slot 1 and the uplink baseline received power of the optical terminal corresponding to the slot 1 is smaller than the set threshold (approximately 0), and the MAC unit 1210 determines that the difference between the received power of the uplink optical signal received in the slot 2-slot 64 and the uplink baseline received power of the optical terminal corresponding to the slot respectively corresponding to the slots is greater than or equal to the set threshold. Further, the MAC unit 1210 determines that the port 1 corresponding to the wavelength 1 is connected to the ONT1 according to the wavelength λ1 of the wavelength tunable laser and the optical terminal corresponding to the received power difference, that is, a binding relationship exists. For another example, the MAC unit 1210 determines that the setting information is not detected in the uplink optical signal received from the slot 1, but is detected in the uplink optical signals received from other slots. Further, the MAC unit 1210 determines that the port 1 corresponding to the wavelength 1 is connected to the ONT1 according to the wavelength λ1 of the wavelength tunable laser and the optical terminal corresponding to the time slot 1. For another example, the MAC unit 1210 determines that the difference between the received power of the uplink optical signal received in the slot 1 and the uplink baseline received power of the optical terminal corresponding to the slot 1 is smaller than the set threshold (approximately 0), the MAC unit 1210 determines that the difference between the received power of the uplink optical signal received in the slot 2-slot 64 and the uplink baseline received power of the optical terminal corresponding to the slot corresponding to each of the slots is greater than or equal to the set threshold, the uplink optical signal received from the slot 1 does not detect the set information, and the uplink optical signals received from other slots all detect the set information, and determines that the port 1 corresponding to the wavelength 1 is connected to the ONT1 according to the wavelength λ1 of the wavelength tunable laser and the optical terminal corresponding to the slot 1.

Further, the MAC unit 1210 controls the wavelength tunable laser 1220 to transmit the pump light signal with the wavelength λ2, and continues to determine the optical terminal connected to the port 2 corresponding to the wavelength λ2. And so on.

It will be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working process of the above-described communication system may refer to the corresponding process in the foregoing method embodiment, which is not repeated herein.

An embodiment of the present application provides a computer readable medium for storing a computer program comprising instructions for performing the method steps in the corresponding method embodiment of fig. 4.

It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims and the equivalents thereof, the present application is intended to cover such modifications and variations.

Claims

1. A method for determining topology of an optical access network, wherein the optical access network includes a plurality of optical terminals, the plurality of optical terminals are optically connected with different ports of an optical splitter in the optical access network in a one-to-one correspondence manner, the method comprising:

Continuously transmitting a detection optical signal of a first wavelength, and controlling the plurality of optical terminals to respectively transmit uplink optical signals on time slots corresponding to each optical terminal; the first wavelength corresponds to a first port of the optical splitter, and different ports of the optical splitter correspond to different wavelengths;

detecting the power of the reflected optical signal of the detected optical signal in the optical signals received on the time slots respectively corresponding to the plurality of optical terminals;

determining an optical terminal connected with the first port corresponding to the first wavelength according to the relation between a time window in which the change of the power of the reflected optical signal is detected in the received optical signal and time slots respectively corresponding to the plurality of optical terminals;

wherein the power change of the reflected optical signal detected in the received optical signal is: and the uplink optical signal of one optical terminal is generated by generating a cross gain modulation effect or a cross attenuation modulation effect in the connecting branch circuit for the detection optical signal and the optical signal obtained by reflecting the detection optical signal by the optical filter in the connecting branch circuit of the optical splitter and the one optical terminal.

2. The method of claim 1, wherein determining the optical terminal to which the first port corresponding to the first wavelength is connected based on a relationship between a time window in which a change in power of a reflected optical signal of a probe optical signal is detected in the received optical signal and time slots respectively corresponding to the plurality of optical terminals, comprises:

3. An optical access network topology determining device is characterized in that the optical access network comprises a plurality of optical terminals, the plurality of optical terminals are in one-to-one correspondence with a plurality of ports of an optical splitter in the optical access network, the device comprises a Media Access Control (MAC) unit, a wavelength-adjustable laser, a photoelectric detector and a circulator, a first port of the circulator is optically connected with the wavelength-adjustable laser, a second port of the circulator is optically connected with the optical splitter, and a third port of the circulator is optically connected with the photoelectric detector;

4. The apparatus of claim 3, wherein the MAC unit is specifically configured to:

5. A method for determining topology of an optical access network, wherein the optical access network includes a plurality of optical terminals, the plurality of optical terminals are optically connected with a plurality of ports of an optical splitter in the optical access network in a one-to-one correspondence manner, the method comprising:

Continuously transmitting a pump optical signal with a first wavelength, and controlling the plurality of optical terminals to respectively transmit an uplink optical signal on a time slot corresponding to each optical terminal; the first wavelength corresponds to a first port of the optical splitter, and different ports of the optical splitter correspond to different wavelengths;

measuring the received power of the uplink optical signals received on the time slots respectively corresponding to the plurality of optical terminals;

determining an optical terminal connected with the first port corresponding to the first wavelength according to the change condition of the received power of each optical terminal in the plurality of optical terminals and the uplink baseline received power of each optical terminal;

6. The method of claim 5, wherein the determining the optical terminal to which the first port corresponding to the first wavelength is connected according to the change of the received power of each optical terminal in the plurality of optical terminals and the uplink baseline received power of each optical terminal comprises:

7. The method of claim 5, wherein the pump optical signal is obtained by modulating setting information, and wherein determining the optical terminal to which the first port corresponding to the first wavelength is connected according to a change in the received power of each of the plurality of optical terminals and the uplink baseline received power of each of the plurality of optical terminals comprises:

8. The method of claim 7, wherein the setting information comprises a setting frequency and/or a setting pattern.

9. The method of any one of claims 5-8, wherein the method further comprises:

10. An optical access network topology determining device is characterized in that the optical access network comprises a plurality of optical terminals, the plurality of optical terminals are in one-to-one corresponding optical connection with a plurality of ports of an optical splitter in the optical access network, and the device comprises a Media Access Control (MAC) unit, an optical module and a wavelength adjustable laser;

11. The apparatus of claim 10, wherein the MAC unit is specifically configured to:

12. The apparatus of claim 10, wherein the pump light signal is modulated by setting information, and the optical module is further configured to detect the setting information from uplink light signals received by respective corresponding timeslots of a plurality of optical terminals;

the MAC unit is specifically configured to:

13. The apparatus of claim 12, wherein the setting information comprises a setting frequency and/or a setting pattern.

14. The apparatus according to any one of claims 10-13, wherein the MAC unit is further configured to control the plurality of optical terminals to transmit uplink optical signals on corresponding timeslots of each optical terminal, respectively, before consecutively transmitting pump optical signals of the first wavelength;

15. A method for determining topology of an optical access network, wherein the optical access network includes a plurality of optical terminals, the plurality of optical terminals are optically connected with a plurality of ports of an optical splitter in the optical access network in a one-to-one correspondence manner, the method comprising:

16. The method of claim 15, wherein determining the optical terminal to which the first port corresponding to the first wavelength is connected according to the detection result of each time slot, comprises:

17. The method according to claim 15 or 16, wherein the setting information comprises a setting frequency and/or a setting pattern.

18. An optical access network topology determining device is characterized in that the optical access network comprises a plurality of optical terminals, the plurality of optical terminals are in one-to-one corresponding optical connection with a plurality of ports of an optical splitter in the optical access network, and the device comprises a Media Access Control (MAC) unit, an optical module and a wavelength adjustable laser;

19. The apparatus of claim 18, wherein the MAC unit is configured to:

20. The apparatus according to claim 18 or 19, wherein the setting information comprises a setting frequency and/or a setting pattern.

21. A system for determining topology of an optical access network, comprising an apparatus according to any one of claims 3-4 or an apparatus according to any one of claims 10-14 or an apparatus according to any one of claims 18-20, the system further comprising an optical distribution network ODN and a plurality of optical terminals, the ODN being optically connected to the plurality of optical terminals, the ODN comprising an optical splitter or a plurality of optical splitters;

22. The system of claim 21, wherein a gain component is further disposed within a connection leg of the optical splitter in the ODN with each of the plurality of optical terminals, the gain component being located between the optical splitter branching end and the optical filter or between the optical filter and the optical terminal;

23. The system of claim 21 or 22, wherein the optical filter is a bragg grating FBG.