A network topology determination method, a passive optical network and related devices

Abstract

Embodiments of the present application disclose a network topology determination method, a passive optical network and related equipment, which are used for reducing the difficulty of determining the topology of the passive optical network. The method comprises the following steps: obtaining sensing signals of a test signal passing through a plurality of end faces in the passive optical network; the plurality of end faces comprise input end faces and / or output end faces of a plurality of optical splitters in the passive optical network, and links between the plurality of optical splitters are in a tree topology; determining end face information of the plurality of end faces according to cross-correlation signals between the test signal and the sensing signals; wherein the end face information is used for determining the topology of the passive optical network.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of network topology, and in particular, to a network topology determination method, a passive optical network and related devices. BACKGROUND

[0002] In a passive optical network, some nodes cannot provide their own node information (for example, passive optical splitters, couplers, etc.), and thus it is necessary to obtain the topology of the passive optical network through a test device. The test device sends a pulse signal to the passive optical network, and determines the distance between each end face in the network and the test device and the information of each end face according to the reflected signal of the pulse signal passing through each end face in the network, thereby determining the network topology.

[0003] However, in this scheme, not only does the test device need to have the ability to transmit and receive the pulse signal, but also sufficient bandwidth needs to be reserved for the pulse signal in the passive optical network to ensure the accuracy of the test result. The available bandwidth in the passive optical network is limited, and reserving bandwidth for the pulse signal will narrow the communication bandwidth used for data transmission, affecting data transmission. SUMMARY

[0004] Embodiments of the present application provide a network topology determination method, a passive optical network and related devices, for reducing the difficulty of determining the topology of a passive optical network.

[0005] In a first aspect, embodiments of the present application provide a network topology determination method. The method is applied to a test device, and the method comprises: the test device obtaining a sensing signal obtained by a test signal passing through a plurality of end faces in a passive optical network. The plurality of end faces comprises input end faces and / or output end faces of a plurality of splitters in the passive optical network. The links between the plurality of splitters are in a tree topology. After obtaining the sensing signal, the test device determines end face information of the plurality of end faces according to a cross-correlation signal between the test signal and the sensing signal. The end face information is used to determine the topology of the passive optical network.

[0006] In embodiments of the present application, since the cross-correlation calculation has a small requirement for the test signal, the test signal required for calculating the cross-correlation signal can be a discrete pulse signal or a continuous signal. If the test signal is set to a continuous signal, the bandwidth occupied by the test signal in the passive optical network can be reduced, thereby reducing the occupation of the communication bandwidth by the test signal and reducing the impact on data transmission. Alternatively, the data signal transmitted in the network can be used as the test signal, and no additional bandwidth needs to be occupied for transmitting the test signal in the process of determining the network topology, and the data transmission is not affected at all.

[0007] In addition, if the test signal is a continuous signal, only the input end face and / or the output end face of the optical splitter in the network needs to be set as a marked end face with a marking function, and the test device only needs to have the function of receiving a continuous signal, so that the existing network architecture, device form, and the like can be reused to determine the network topology. In this scheme, the test device does not need to have the ability to send and receive pulse signals. Since the cost of the marked end face and the test device with the function of receiving a continuous signal is much lower than the cost of the test device with the ability to send and receive pulse signals, the method provided in the embodiments of the present application can reduce the cost required to determine the network topology.

[0008] In addition, in the calculation of the cross-correlation signal, the influence of noise, errors, and the like carried by the test signal and the sensing signal can be eliminated, so that the end face information and the network topology determined according to the cross-correlation signal are more accurate.

[0009] It should be noted that the passive optical network in the embodiments of the present application refers to a point-to-multipoint passive optical network. In addition to the passive optical network (PON) in the general sense, the passive optical network can also refer to a passive optical LAN (POL), and the like, which is not limited in the present application.

[0010] In an optional implementation, the plurality of end faces include a plurality of Fabry-Perot (F-P) cavities. The end face information includes lengths of the plurality of F-P cavities and an up-down relationship between the plurality of F-P cavities.

[0011] In the embodiments of the present application, the F-P cavity is used as a marked end face to mark the optical splitter at different positions. Since the F-P cavity has a simple structure, low cost, and is easy to install, the scheme has high implementability and low modification cost.

[0012] In an optional implementation, the cross-correlation signal includes a relative intensity. In the embodiments of the present application, the relative intensity is the relative intensity of the cross-correlation peaks of the test signal and the sensing signal at different wavelengths and different time domain positions.

[0013] In an optional implementation, the test device can determine the lengths of the F-P cavities at different time domain positions according to the relative intensity distribution of the cross-correlation signals at different wavelengths at different time domain positions.

[0014] In the embodiments of the present application, the method for determining the reflection signal position using the cross-correlation operation can directly reuse a continuous downstream data signal (or a downstream service signal) as a test signal without using an additional test signal.

[0015] In an alternative implementation, the testing device can determine the length of the first F-P cavity at the first time domain position according to the relative intensity distribution of the cross-correlation signal at different wavelengths at the first time domain position. The first time domain position is the time domain position where the cross-correlation peak is located in the cross-correlation signal. This method does not need to perform complex transformation and the operation process is simple.

[0016] In an alternative implementation, the testing device can perform domain transformation on the relative intensity distribution curve of the cross-correlation signal at different wavelengths at the second time domain position to obtain a spectral distribution curve at the second time domain position. The second time domain position is the time domain position where the cross-correlation peak is located in the cross-correlation signal. Then, the testing device can determine the length of the F-P cavity at the second time domain position according to the peak spacing of a family of peaks in the spectral distribution curve (the family of peaks includes a main peak and two side peaks, and the peak spacing is the distance between the main peak and any side peak).

[0017] In the embodiments of the present application, the wavelength-relative intensity distribution of the cross-correlation signal at the second time domain position is subjected to domain transformation, and the length of the F-P cavity at the second time domain position is obviously characterized in the obtained spectral distribution curve, and the length of the F-P cavity is easier to determine.

[0018] In an alternative implementation, the testing device can determine the superior-inferior relationship between the F-P cavities at different time domain positions according to the relative intensity distribution of the cross-correlation signal at different wavelengths at different time domain positions.

[0019] Generally, only the distances between the multiple end faces and the testing device in the passive optical network can be determined by the pulse signal. In the embodiments of the present application, the connection relationship between the multiple end faces in the passive optical network can be determined by the above method, and more topology information is obtained, so that the topology of the passive optical network can be determined according to the distances between the end faces and the testing device and the connection relationship between the end faces.

[0020] In an alternative implementation, the testing device can determine the superior F-P cavity that has a connection relationship with the target F-P cavity in the superior F-P cavity of the target F-P cavity according to the first distribution corresponding to the target F-P cavity and the reflectivity and / or transmissivity of the superior F-P cavity of the target F-P cavity. The first distribution is the relative intensity distribution of the cross-correlation signal at different wavelengths at the time domain position where the target F-P cavity is located, and the time domain position where the target F-P cavity is located is the time domain position where the cross-correlation peak is located in the cross-correlation signal. This method analyzes the connection relationship between the F-P cavities in the time domain, which can reduce the sampling rate and the sampling data.

[0021] In an alternative implementation, the first distribution corresponding to the target F-P cavity satisfies the following corresponding relationship:

[0022]

[0023] wherein, S b+1 (v) represents the first distribution corresponding to the target F-P cavity, i.e. the relative intensity distribution of the cross-correlation signal at different wavelengths at the time-domain position where the target F-P cavity is located. i (v) represents the transmissivity of the upper F-P cavity having a connection relationship with the target F-P cavity. n+1 (v) represents the reflectivity of the target F-P cavity. I0 represents the emission light intensity of the test signal. v represents the carrier frequency of the test signal, used to represent the wavelength corresponding to the test signal.

[0024] In an alternative implementation, the test device can perform domain transformation on the first distribution curve corresponding to the target F-P cavity to obtain a target spectral distribution curve corresponding to the target F-P cavity. The first distribution curve is a distribution curve of the relative intensity of the cross-correlation signal at different wavelengths at the time-domain position where the target F-P cavity is located, and the time-domain position where the target F-P cavity is located is the time-domain position of the cross-correlation peak in the cross-correlation signal. The test device can also perform domain transformation on the respective reference distribution curves of the at least one upper F-P cavity corresponding to the target F-P cavity to obtain the respective reference spectral distribution curves of the at least one upper F-P cavity. The reference distribution curve is a distribution curve of the relative intensity of the cross-correlation signal at different wavelengths at the time-domain position where the corresponding upper F-P cavity is located. After obtaining the target spectral distribution curve and the reference spectral distribution curves corresponding to the at least one upper F-P cavity, the test device can determine the spectral distribution curve of the upper F-P cavity having a connection relationship with the target F-P cavity from the respective reference spectral distribution curves of the at least one upper F-P cavity according to the target spectral distribution curve, thereby determining the upper F-P cavity having a connection relationship with the target F-P cavity.

[0025] The method analyzes the connection relationship of the F-P cavity in the frequency domain, and has the advantages of simple algorithm and high efficiency. In the embodiments of the present application, as long as the lengths of the F-P cavities connected to the same splitter are different, the spectral distribution curve can be used to distinguish the F-P cavities of the same level, thereby distinguishing all the F-P cavities in the passive optical network. The method can reduce the requirement for the length of the F-P cavity (it is not required that the length of each F-P cavity is different, and part of the F-P cavities in the network can be selected to have the same length. For example, the lengths of the F-P cavities of different levels, or the F-P cavities of the same level connected to different splitters, can be the same), thereby reducing the cost of network reconstruction or construction.

[0026] In an optional implementation, the test signal includes test signals of different wavelengths, and the sensing signal includes sensing signals of the different wavelengths. The test device can further determine, according to the test signal of each wavelength and the corresponding sensing signal, a relative intensity distribution of the cross-correlation signal of each wavelength at different time domain positions. Then, the test device can obtain, according to the relative intensity distribution of the cross-correlation signal of the different wavelengths at different time domain positions, a relative intensity distribution of the cross-correlation signal at different time domain positions at different wavelengths. In the embodiments of the present application, the process is referred to as scanning, specifically, scanning of wavelengths.

[0027] In the embodiments of the present application, by scanning of wavelengths, only one wavelength of test signal is transmitted at the same time, and the existing data transmission method in the passive optical network can be reused, which is better compatible with the existing network.

[0028] In an optional implementation, the test signal is a downstream data signal, and the sensing signal is a reflection signal of the downstream data signal after passing through a plurality of end faces.

[0029] In the embodiments of the present application, the downstream data signal is reused as the test signal, and the test signal does not need to be separately transmitted and transmitted in the network. On the one hand, the upstream side of the network (such as an optical line termination (OLT), an optical time domain reflectometer (OTDR), etc.) does not need to modify the data transmission unit or module, which is better compatible with the existing transmission equipment and reduces the modification cost of the transmission equipment. On the other hand, a part of the bandwidth in the network does not need to be divided for transmitting the test signal (directly using the bandwidth of the communication band to transmit the data signal), which does not occupy the communication band and reduces the impact on data transmission.

[0030] In an optional implementation, the test device can further obtain an upstream data signal from the passive optical network and analyze the upstream data signal. The time for obtaining the upstream data signal is different from the time for obtaining the sensing signal.

[0031] In the embodiments of the present application, the test device obtains the upstream data signal and the sensing signal by time division multiplexing. The test signal (sensing signal) can be in the communication band, so it does not need to expand the band range of the entire network, and the change of the network is small.

[0032] In an alternative implementation, the plurality of facets in the passive optical network further comprises a target facet of a non-F-P cavity. The cross-correlation signal comprises a relative intensity. The testing device can determine a target distribution that is isomorphic to a relative intensity distribution corresponding to the target facet in a set of relative intensity distributions. The set of relative intensity distributions is a set of relative intensity distributions of the cross-correlation signal at different wavelengths at a plurality of time domain locations. The relative intensity distribution corresponding to the target facet is a relative intensity distribution of the cross-correlation signal at different wavelengths at a time domain location where the target facet is located. Then, the testing device can determine that there is a connection relationship between the F-P cavity at the time domain location corresponding to the target distribution and the target facet.

[0033] In the embodiments of the present application, the target facet of the non-F-P cavity, also referred to as a non-marked facet, can include a cross section, a suspended surface, etc. By analyzing the wavelength-relative intensity distribution of the cross-correlation signal at the time domain location where the non-marked facet is located, the non-marked facets in the passive optical network can be determined, thereby discovering dark fibers, optical fiber cross sections, etc. between or outside the splitter nodes, and obtaining more detailed network topology information.

[0034] In an alternative implementation, the testing device can further determine the distances between the plurality of facets according to the cross-correlation signal between the test signal and the sensing signal. Then, the testing device can determine the network structure of the passive optical network according to the distances between the plurality of facets and the topology of the passive optical network.

[0035] In a second aspect, the embodiments of the present application provide a passive optical network comprising a plurality of splitters, a plurality of facets, and a testing device. The links between the plurality of splitters are in a tree topology. The plurality of facets comprises input facets and / or output facets of the plurality of splitters. The testing device is configured to obtain a sensing signal of a test signal passing through the plurality of facets, and determine facet information of the plurality of facets according to a cross-correlation signal between the test signal and the sensing signal. The facet information is used to determine the topology of the passive optical network.

[0036] In an alternative implementation, the testing device is configured to implement the network topology determination method of the first aspect.

[0037] In the embodiments of the present application, the input facets and / or output facets of the plurality of splitters in the passive optical network are marked, so that the testing device can determine the network topology. This scheme only needs to set the input facets and / or output facets of the splitters as marked facets with marking effect, and the network topology can be determined by modifying the passive optical network to a lesser extent.

[0038] In an alternative implementation, the plurality of facets comprises a plurality of F-P cavities. The lengths of the plurality of F-P cavities connected to the same splitter are different from each other.

[0039] In the embodiments of the present application, as long as the lengths of the same-stage F-Ps connected under the same optical splitter are different, all the F-P cavities in the passive optical network can be distinguished, the requirement for the length of the F-P cavity is reduced (it is not required that the length of each F-P cavity is different, and some F-P cavities in the network can be selected as F-P cavities with the same length), and the cost of network reconstruction or construction is reduced.

[0040] In an optional implementation, the length of any F-P cavity in the plurality of F-P cavities is 10 n meter level. Wherein, -4≤n≤-2.

[0041] The smaller the length of the F-P cavity is, the smaller the FSR is, and the smaller the tolerance range of the length of the F-P cavity is determined. The larger the length of the F-P cavity is, the higher the complexity of signal analysis is. The length range of the cavity is designed to balance the tolerance of the F-P cavity device and the complexity of signal analysis.

[0042] In a third aspect, the embodiments of the present application provide a test device. The test device is applied to a passive optical network. The passive optical network includes a plurality of optical splitters and a plurality of end faces. Wherein, the links between the plurality of optical splitters are in a tree topology, and the plurality of end faces include input end faces and / or output end faces of the plurality of optical splitters. The test device includes a transceiver unit and a processing unit. Wherein, the transceiver unit is configured to obtain sensing signals of a test signal obtained through the plurality of end faces. The processing unit is configured to determine end face information of the plurality of end faces according to cross-correlation signals between the test signal and the sensing signals. The end face information is used to determine a topology of the passive optical network.

[0043] The test device is used to implement the network topology determination method of the first aspect. The test device is the test device in the passive optical network of the second aspect.

[0044] The beneficial effects of the third aspect are described in the first aspect and the second aspect, and will not be repeated here.

[0045] In an optional implementation, the plurality of optical splitters includes N optical splitters, and the test device receives sensing signals of different wave bands from the N optical splitters. The test device further includes N F-P cavities corresponding to the N optical splitters one by one. The transceiver unit is specifically configured to obtain the sensing signals of different wave bands from the N optical splitters through the N F-P cavities.

[0046] This implementation uses the N F-P cavities inside the test device to mark the N optical splitters (which are the highest-stage optical splitters in the passive optical network) of the passive optical network. The data transmission link inside the test device is divided into N links, so that the test device can directly control which link to transmit and receive signals on, without the need for external devices. This avoids the use of expensive devices such as optical selectors, and significantly reduces the cost.

[0047] In an optional implementation, the test device comprises an optical integrated chip. The optical integrated chip comprises a transceiver unit and an optical ring unit. The transceiver unit comprises a first photodetector and a second photodetector. The optical ring unit is configured to separate the upstream sensing signal and send the upstream sensing signal to the first photodetector. The first photodetector is configured to acquire the upstream sensing signal from the passive optical network through the optical ring unit. The second photodetector is configured to acquire the upstream data signal from the passive optical network.

[0048] In the embodiments of the present application, the optical ring unit is no longer an independent device. The optical ring unit is integrated on the optical integrated chip, so that the test device has high integration and compact structure, and can meet the requirement of device miniaturization.

[0049] In an optional implementation, the transceiver unit comprises a photodetector. The photodetector is configured to receive the data signal and the sensing signal from the passive optical network at different time points respectively. The test device further comprises a transimpedance amplifier configured to amplify the sensing signal from the photodetector according to a first gain coefficient, and amplify the data signal from the photodetector according to a second gain coefficient. The second gain coefficient is less than the first gain coefficient.

[0050] In the embodiments of the present application, the photodetector in the test device receives the data signal and the sensing signal by the method of time division multiplexing. Multiple photodetectors do not need to be arranged to receive the data signal and the sensing signal respectively, so that the number of components in the test device is reduced, and the volume and cost of the test device can be reduced.

[0051] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program. When the computer program is executed, the method of the first aspect is implemented.

[0052] In a fifth aspect, the present application provides a computer readable storage medium, which stores a computer program. When the computer program is executed, the method of the first aspect is implemented.

[0053] The beneficial effects of the fourth aspect and the fifth aspect are described in the first aspect, and will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 FIG. 1 is a schematic diagram of a passive optical network according to an embodiment of the present application;

[0055] Figure 2a FIG. 1 is a schematic diagram of a passive optical network according to an embodiment of the present application;

[0056] Figure 2bAnother schematic diagram of a passive optical network provided for an embodiment of the present application;

[0057] Figure 3 A flowchart of a network topology determination method provided for an embodiment of the present application;

[0058] Figure 4 A flowchart of a process of determining end face information of a test device provided for an embodiment of the present application;

[0059] Figure 5 A wavelength-relative intensity distribution of a cross-correlation signal at a time domain position provided for an embodiment of the present application;

[0060] Figure 6 A wavelength-relative intensity distribution of a cross-correlation signal at a plurality of time domain positions provided for an embodiment of the present application;

[0061] Figure 7 A schematic diagram of determining a FSR of a F-P cavity through a wavelength-relative intensity distribution of a cross-correlation signal in an embodiment of the present application;

[0062] Figure 8 A schematic diagram of determining a connection relationship between end faces provided for an embodiment of the present application;

[0063] Figure 9 A schematic diagram of determining a connection relationship between end faces through a spectral distribution curve provided for an embodiment of the present application;

[0064] Figure 10 A flowchart of a network topology determination method when a test signal is a downstream data signal provided for an embodiment of the present application;

[0065] Figure 11 A schematic diagram of a structure of a test device provided for an embodiment of the present application;

[0066] Figure 12 Another schematic diagram of a structure of a test device provided for an embodiment of the present application;

[0067] Figure 13 Another schematic diagram of a structure of a test device provided for an embodiment of the present application;

[0068] Figure 14 Another schematic diagram of a structure of a test device provided for an embodiment of the present application;

[0069] Figure 15 Another schematic diagram of a structure of a test device provided for an embodiment of the present application;

[0070] Figure 16 Another schematic diagram of a structure of a test device provided for an embodiment of the present application. DETAILED DESCRIPTION

[0071] Embodiments of the present application provide a network topology determination method, a passive optical network and related devices, which are used to reduce the difficulty of determining the topology of the passive optical network.

[0072] In the field of optical communication, the transmission of optical signals is implemented through a passive optical network. As shown in Figure 1 , the passive optical network includes an optical line termination (OLT), an optical distribution network (ODN), and an optical network unit (ONU) and / or an optical network terminal (ONT).

[0073] The OLT is used to connect a fiber trunk, implement flow scheduling, buffer control, provide a user-oriented passive optical fiber network interface, and allocate bandwidth. The OLT is a passive and point-to-multipoint optical fiber network. The ODN is used to provide an optical transmission channel between the OLT and the ONU and / or the ONT. The ONU is an optical network device connected to the branch optical fiber of the ODN. The ONT is an optical network device connected to the end user. The ONT can be a component of the ONU or a downstream device of the ONU, which is not limited in the present application.

[0074] It should be noted that the passive optical network appearing in the embodiments of the present application can be a passive optical network (PON) in the general sense, or can represent a passive optical LAN (POL), etc., which is not limited in the present application.

[0075] Since the passive optical network is passive, that is, some nodes (such as splitters, couplers, etc. in the ODN) in the passive optical network do not actively send their own information, it is difficult to obtain the topology of the passive optical network. Based on this, the embodiments of the present application provide a network topology determination method, a passive optical network and related devices. By using an end face with a marking function, the difficulty of determining the topology of the passive optical network is reduced.

[0076] First, the passive optical network provided by the embodiments of the present application is described. As shown in Figure 2a , the passive optical network provided by the embodiments of the present application includes a plurality of splitters, a plurality of end faces and a test device.

[0077] The links between the plurality of splitters are in a tree topology. The splitters are classified by the present application, and each upper-level splitter is used to connect one or more lower-level splitters. For example, Figure 2aIn the example, beam splitter 1 connects to two lower-level beam splitters 1-1 and 1-2; beam splitter 1-1 connects to two lower-level beam splitters 1-1-1 and 1-1-2. It is worth noting that the terms "upper-level beam splitter" and "lower-level beam splitter" in this embodiment are relative concepts. For example, beam splitter 1-1 is an upper-level beam splitter relative to beam splitter 1-1-1, but a lower-level beam splitter relative to beam splitter 1.

[0078] It is worth noting that, Figure 2a Taking the example of each optical splitter connecting two downstream optical splitters, this does not impose any limitations on the links between the optical splitters. The number of downstream optical splitters connected to each optical splitter can be fewer or more, and this application does not impose any limitations on this.

[0079] Figure 2a Taking the output end face as an example, it does not impose any limitations on the positional relationship between the end face and the beam splitter. For example... Figure 2b As shown, multiple end faces may also include the input end faces of multiple beam splitters. Alternatively, some end faces may be input end faces of beam splitters, and some end faces may be output end faces of other beam splitters; this application does not limit this. In the embodiments of this application, the output end face and / or input end face of the beam splitter are called marking end faces, used to mark the corresponding beam splitter. It is worth noting that, in addition to marking end faces, the end faces in the embodiments of this application may also include non-marking end faces (such as...). Figure 2b (As shown). The unmarked end face can be a cross-section, a suspended surface, etc., and this application does not limit it.

[0080] Optionally, the marking end face can be a Fabry-Perot (FP) cavity. Different FP cavities are distinguished by their length. Therefore, in order to differentiate multiple FP cavities connected to the same beam splitter, in this embodiment, the lengths of multiple FP cavities of the same level connected to the same beam splitter are different.

[0081] The testing equipment is used to acquire the sensor signals obtained from the test signal through multiple end faces, and to determine the end face information of the multiple end faces based on the cross-correlation signal between the test signal and the sensor signals. This end face information is used to determine the topology of the passive optical network.

[0082] Optionally, Figure 2a or Figure 2b The network structure shown is nested Figure 1In the shown passive optical network, the plurality of splitters can be splitters in the ODN; the marked end faces can be input end faces and / or output end faces of the splitters in the ODN, for marking the splitters in the ODN; the test device can be an OLT, an optical time domain reflectometer (OTDR), a network management device of the passive optical network, etc., which are not limited in the present application.

[0083] The specific process in which the test device acquires the end face information, i.e., the flow of the network topology determination method provided by the embodiments of the present application, is shown in Figure 3 The method comprises the following steps:

[0084] 301. The test device acquires a sensing signal obtained by a test signal passing through a plurality of end faces in a passive optical network.

[0085] The test signal can obtain a sensing signal after passing through a plurality of end faces in a passive optical network. The test device can acquire the sensing signal.

[0086] Optionally, the test device can be an OLT or an OTDR as shown in Figure 1 The test device can send a test signal to the ODN. The test signal is reflected by a plurality of end faces in the network, and the reflected signal is received by the test device. The reflected signal received by the test device is called a sensing signal.

[0087] In the embodiments of the present application, the sensing signal is transmitted in the form of an optical signal in the passive optical network. However, the test device processes signals in the form of an electrical signal. Therefore, in the process of acquiring the sensing signal, the test device can convert the acquired sensing signal in the form of an optical signal into an electrical signal (for example, when the test device is an OLT or an OTDR); or the test device can receive the converted sensing signal in the form of an electrical signal (for example, when the test device is a network device), and the device subject to the conversion of the sensing signal into an electrical signal (for example, it can be an optical module, an optical board card, etc.) is not limited in the present application.

[0088] 302. The test device determines end face information of the plurality of end faces according to a cross-correlation signal between the test signal and the sensing signal, the end face information being used to determine a topology of the passive optical network.

[0089] After acquiring the sensing signal, the test device can determine the end face information of each end face in the network according to a cross-correlation signal between the test signal and the sensing signal. In the embodiments shown in Figure 2a and Figure 2b It has been stated in the embodiments shown in

[0090] Optionally, the end-face information determined by the cross-correlation signal may include: information about each marked end-face and the connection relationship between each marked end-face. In addition, the end-face information may also include the classification of the marked end-face, the end-face position, etc., which are not limited in this application.

[0091] End-face information (such as information about each marked end-face and the connection relationships between each marked end-face) can be used to determine the topology between each marked end-face, thereby determining the topology between the corresponding multiple optical splitters and reconstructing the topology of the passive optical network. Optionally, the process of determining the topology of the passive optical network based on the end-face information can be implemented by testing equipment or by other equipment (such as network management equipment), and this application does not limit this.

[0092] In this embodiment, since the cross-correlation calculation requires minimal test signal input, the test signal needed for calculation can be either a discrete pulse signal or a continuous signal. Setting the test signal to a continuous signal reduces the bandwidth occupied by the test signal in the passive optical network, thereby reducing the bandwidth consumption of the test signal and minimizing its impact on data transmission. Optionally, the data signal transmitted in the network can be used as the test signal; in this case, no additional bandwidth is needed for transmitting the test signal during the network topology determination process, and data transmission is not affected at all.

[0093] Furthermore, if the test signal is a continuous signal, it is only necessary to set the input and / or output faces of the optical splitters in the network as marked faces. The test equipment only needs to have the ability to receive continuous signals to reuse existing network architecture and equipment configurations to determine the network topology. In this approach, the test equipment does not need to have the ability to transmit and receive pulse signals. Since the cost of marked faces and test equipment capable of receiving continuous signals is far lower than the cost of test equipment capable of transmitting and receiving pulse signals, the method provided in this application can reduce the cost required to determine the network topology.

[0094] Furthermore, the calculation of cross-correlation signals can eliminate the influence of noise and errors carried by the test signals and sensor signals, making the end-face information and network topology determined based on the cross-correlation signals more accurate.

[0095] Optionally, the marking end face may include a Fabry-Perot (FP) cavity. An FP cavity is a resonant cavity composed of two parallel reflecting surfaces. In the embodiments of this application, different FP cavities can be distinguished by their length. The specific process for determining the length of the FP cavity is as follows: Figure 4 As shown, the process includes:

[0096] 401. Test the equipment and perform system initialization.

[0097] 402、The testing device sets the carrier wavelength λi of the test signal.

[0098] The testing device sets the carrier wavelength λi of the test signal, and transmits the test signal with the carrier wavelength λi in the passive optical network.

[0099] Optionally, if the testing device is a device capable of sending test signals such as OLT or OTDR, the testing device can directly send the test signal with the carrier wavelength λi in step 402. If the testing device does not have the function of sending test signals, the testing device will send the determined λi to the device for sending test signals in step 402, so that the device sends the test signal with the carrier wavelength λi.

[0100] 403、The testing device obtains the time-domain position-relative intensity distribution of the cross-correlation signal under the carrier wavelength λi.

[0101] The test signal with the carrier wavelength λi passes through multiple end faces in the passive optical network to obtain a sensing signal with the carrier wavelength λi. The testing device can obtain the sensing signal with the carrier wavelength λi. Then, the testing device can perform cross-correlation calculation on the test signal with the carrier wavelength λi and the sensing signal to obtain the cross-correlation signal under the carrier wavelength λi. Optionally, the cross-correlation signal between the test signal and the sensing signal can be calculated by formula 1.

[0102]

[0103] Wherein, r[t] represents the test signal, s[t+Δt] represents the sensing signal, and h[Δt] represents the relative intensity of the cross-correlation peak between the test signal and the sensing signal. t0 and t m are the start and end points of the calculation time window of the cross-correlation signal, and N is the number of sampling points in the time window. Δt represents the time length required for the test signal to be transmitted from the sending end (such as the testing device) to the F-P cavity. In the embodiments of the present application, Δt is also referred to as the time-domain position of the end face, which is used to determine the distance between the corresponding end face and the testing device (distance=c×Δt, c is the speed of light).

[0104] Through the calculation of formula 1, the relative intensity (h[Δt]) distribution of the cross-correlation signal with the carrier wavelength λi at different time-domain positions (Δt) can be obtained as shown in Figure 5 Figure 5 ​As shown, the relative intensity distribution of the cross-correlation signal at different time-domain positions (i.e., the time-domain position-relative intensity distribution of the cross-correlation signal) includes multiple peaks. In embodiments of the present application, the peaks in the time-domain position-relative intensity distribution of the cross-correlation signal are referred to as cross-correlation peaks. The time-domain position where the cross-correlation peak is located is where the end face exists. The end face here can include a marked end face and an unmarked end face, which are not limited in the present application.

[0105] Alternatively, r[t] and s[t+Δt] can be power-normalized sequences. By power normalization, the noise in the test signal and the sensing signal can be reduced, thereby reducing the influence of the noise on the cross-correlation signal and improving the accuracy of the determined results (end face information and network topology determined according to the end face information).

[0106] After step 403, the test device can adjust the carrier wavelength λi of the test signal, so as to perform steps 402 and 403 at different carrier wavelengths λi to obtain the time-domain position-relative intensity distribution of the cross-correlation signal at different λi. In embodiments of the present application, the process of adjusting the carrier frequency λi of the test signal to perform steps 402 and 403 at different λi is referred to as scanning.

[0107] Alternatively, in step 402, the test device or other device that transmits the test signal can adjust the carrier wavelength λi of the test signal by adjusting the temperature, adjusting the current, etc., which are not limited in the present application.

[0108] 404, the test device obtains the wavelength-relative intensity distribution P(λ) of the cross-correlation signal at different time-domain positions m .

[0109] By scanning, the test device can obtain the time-domain position-relative intensity distribution at different wavelengths. As shown, by representing the time-domain position-relative intensity distribution at different wavelengths in the same three-dimensional coordinate system, the wavelength-relative intensity distribution of the cross-correlation signal at different time-domain positions can be obtained, i.e., Figure 6 . Figure 6 The thicker curve in the wavelength-relative intensity distribution P(λ) at different time-domain positions.

[0110] In step 403, the time-domain position-relative intensity distribution curve of the cross-correlation signal at a single wavelength (i.e., the thicker curve in Figure 5 or Figure 6 ) includes a curve peak (i.e., a cross-correlation peak). The time-domain position where the curve peak is located is the time-domain position where the end face exists. Therefore, in step 404, the wavelength-relative intensity distribution of the cross-correlation signal (i.e., the multiple thicker curves in Figure 6 ) at different time-domain positions can be obtained at the time-domain position where the cross-correlation peak is located, which is referred to as the P(λ) of the cross-correlation signal at different time-domain positions in embodiments of the present application. m .

[0111] 405. Test equipment for P m (λ) is used for filtering.

[0112] During signal transmission, the signal may be affected by noise, etc., therefore the testing equipment must monitor P. m (λ) is used for filtering to reduce the impact of noise and improve the accuracy of calculation results (end face information, network topology, etc.).

[0113] 406. The test equipment is based on the filtered P m (λ) Determines the end face information.

[0114] Will Figure 6 We can isolate and analyze the wavelength-relative intensity curve at a specific time-domain location. For example, suppose... Figure 6 The end face of the cross-correlation peak with the smallest Δt in the time domain is: Figure 2b The input port of beam splitter 1. Then the wavelength-relative intensity distribution at this time-domain location is as follows: Figure 7 As shown, the distribution curve is roughly the shape of a sine wave. The distance between two adjacent peaks of this sine wave is the free spectral range (FSR) of the FP cavity at that time-domain location. The length of the FP cavity and its free spectral range (FSR) have the following correspondence:

[0115]

[0116] Where Δλ represents the FSR of the FP cavity; λ represents the wavelength of the test signal incident on the FP cavity (i.e., the carrier wavelength λi in steps 402 and 403), which is also the wavelength of the corresponding sensing signal and cross-correlation signal. Since the change of λi during the scanning process is small, a value of λi during the scanning process can be taken as the value of λ; n represents the refractive index of the FP cavity; and l represents the length of the FP cavity. It is worth noting that the length of the FP cavity described in this embodiment represents the distance between the two reflecting surfaces in the FP cavity. That is, the length l of the FP cavity can be calculated using Formula 1 and the FSR of the FP cavity (i.e., Δλ in Formula 2).

[0117] This application embodiment uses cross-correlation calculations to retain the pulse information of the test signal and the sensing signal at the time domain location of the end face (i.e., the wavelength-relative intensity distribution at the time domain location of the cross-correlation peak). Figure 6The FSR size of the end face (F-P cavity) is determined according to the pulse information, and the length of the F-P cavity is determined. Compared with determining the length of the F-P cavity by the test signal in the form of pulses, the method of the present application can extract the pulse information from the continuous signal (for example, continuous data signal), and the change required for obtaining the pulse information is mainly in the operation mode of the test device (that is, the test device needs to perform cross-correlation calculation), and the form of the signal transmitted in the network does not need to be changed (no pulse signal needs to be transmitted), thereby reducing the change of the network.

[0118] If a test signal passes through multiple end faces in the network to obtain a sensing signal, and the distribution curve of the cross-correlation signal obtained according to the test signal and the sensing signal, the information of the multiple end faces through which the sensing signal passes will be included. Then, in order to obtain the length of the F-P cavity passed according to the information, the signal needs to be analyzed step by step.

[0119] As shown in Figure 8 , if the test signal is sent from the test device, and the sensing signal is the reflected signal of the test signal passing through multiple end faces in the passive optical network. Then, based on the sensing signal passing through only the input end face of the optical splitter 1 (that is, end face 1 in the figure), the wavelength-relative intensity distribution curve of the cross-correlation signal at the time domain position of the end face 1 is shown in Figure 8 a figure. The sensing signal passing through the end face 1-1 will pass through the end face 1, and the obtained distribution curve is actually the superposition of the distribution curve passing through only the end face 1 (that is, the a figure in Figure 8 ) and the distribution curve passing through only the end face 1-1 (that is, the b figure in Figure 8 ), that is, the thicker curve in the c figure in Figure 8 . In order to determine the length of the F-P cavity of the end face 1-1, it is necessary to separate the distribution curve passing through only the end face 1-1 from the superimposed curve, and then it is necessary to determine the end face 1 connected with the end face 1-1.

[0120] Therefore, after obtaining the wavelength-relative intensity distribution curves of the cross-correlation signals at different time domain positions as shown in Figure 6 , starting from the smaller time domain position, the length of the F-P cavity at the time domain position where the wavelength-relative intensity distribution curve with a sinusoidal waveform is located is analyzed first. Then, the transmittance Ti of the F-P cavity with the known length can be determined according to formula 3, and the reflectance R of the target F-P cavity can be determined according to formula 4 n+1 :

[0121]

[0122]

[0123] Then, for the target F-P cavity located at a larger time domain position, the upper F-P cavity having a connection relationship with the target F-P cavity is determined in the F-P cavity with known length (i.e. the upper F-P cavity of the target F-P cavity) through the following formula 5.

[0124]

[0125] wherein S n+1 (v) represents the first distribution corresponding to the target F-P cavity, i.e. the wavelength-relative intensity distribution of the cross-correlation signal at the time domain position where the target F-P cavity is located. i (v) represents the transmissivity of the upper F-P cavity having a connection relationship with the target F-P cavity. n+1 (v) represents the reflectivity of the target F-P cavity. I0 represents the emission light intensity of the test signal. v represents the carrier frequency of the test signal, used to represent the wavelength corresponding to the test signal.

[0126] Optionally, in the passive optical network, there are also non-marked end faces such as section faces, suspended faces, etc. The cross-correlation signal will also have a cross-correlation peak at the time domain position where the non-marked end face is located, and the wavelength-relative intensity distribution at the time domain position can be obtained. Since the non-marked end face does not reflect the passing signal multiple times as the F-P cavity does, the wavelength-relative intensity distribution will not have a significant change in shape after passing through the non-marked end face.

[0127] Therefore, for the non-marked end face, the target distribution isomorphic to the wavelength-relative intensity distribution at the time domain position where the non-marked end face is located can be determined in the multiple wavelength-relative intensity distributions of the upper end face (which can include the upper F-P cavity and the upper non-marked end face) of the non-marked end face. The end face at the time domain position corresponding to the determined target distribution is the upper end face having a connection relationship with the non-marked end face. In the embodiments of the present application, isomorphic means linear change of the curve, such as scaling, translation, etc.

[0128] For example, for the end face 1-2.5 in Figure 8 the upper end face of which includes the end face 1, the end face 1-1 and the end face 1-2. In the wavelength-relative intensity distributions at the time domain positions of the three end faces, it can be determined that the wavelength-relative intensity distribution at the time domain position of the end face 1-2 is isomorphic to the wavelength-relative intensity distribution corresponding to the end face 1-2.5, and thus it is determined that the non-marked end face 1-2.5 has a connection relationship with the end face 1-2.

[0129] Optionally, there can also be non-marked end faces on the link between the target F-P cavity and the test device. Therefore, in formula 5, Ti(v) can represent the transmissivity of the upper end face (including the upper F-P cavity and the upper non-marked end face) having a connection relationship with the target F-P cavity. For example, for the end face 1-2.5 in Figure 8The transmittance of the non-marked end face 1-2.5 can be substituted into formula 5 to determine the connection relationship of the end face 1-2-2.

[0130] By formula 5 and the above-mentioned isomorphism determination method, all the superior end faces (including superior F-P cavities and superior non-marked end faces) having a connection relationship with the target end face (including the target F-P cavity and the target non-marked end face) can be determined. These superior end faces are all the end faces through which the link between the test device and the target end face passes. The connection relationship can be used to restore the network topology, and thus belongs to part of the end face information.

[0131] Generally, only the distances between multiple end faces in a passive optical network and a test device can be determined by a pulse signal. By the above-mentioned method, the present embodiment can determine the connection relationship between multiple end faces in a passive optical network, so that more topology information can be obtained, and thus the topology of the passive optical network can be obtained according to the distances between the end faces and the test device and the connection relationship between the end faces.

[0132] After all the superior end faces having a connection relationship with the target F-P cavity are determined, the test device can separate the distribution curve of the signal only passing through the target F-P cavity from the wavelength-relative intensity distribution at the time domain position where the target F-P cavity is located, based on the wavelength-relative intensity distribution of the superior end faces, so as to determine the FSR of the target F-P cavity. Figure 8

[0133] Alternatively, in addition to the above-mentioned method, the present embodiment also provides a method for determining the length of an F-P cavity and the connection relationship between end faces by a spectral distribution curve. The test device can perform domain transformation on the wavelength-relative intensity distribution curve at different time domain positions to obtain a spectral distribution curve as shown in Figure 9 Then, the test device can determine the FSR of the F-P cavity at the corresponding time domain position according to the peak spacing of a family of peaks in the spectral distribution curve, so as to determine the length of the F-P cavity at the time domain position.

[0134] For example, Figure 8 The wavelength-relative intensity distribution at the time domain position where the end face 1 is located is shown in a of Figure 8 The domain transformation can be performed on a to obtain Figure 9 ​The d graph consists of a main peak and two side peaks, and the distance between the two side peaks and the main peak is the same. The distance between the main peak and any one of the side peaks is the FSR. The main peak represents the DC component of the biased sinusoidal signal, and the side peak represents the sinusoidal component of the biased sinusoidal signal. It is worth noting that in the spectral distribution curve, in addition to the main peak and the side peak, there can be more peaks, which are not limited in the present application.

[0135] As shown in Figure 8 , if the test signal is sent from the test device, the sensing signal is the reflected signal of the test signal through the multiple end faces in the passive optical network. The sensing signal passing through the end face 1-1 must pass through the end face 1. The spectral distribution curve obtained by the domain transformation of the wavelength-relative intensity distribution curve at the time domain position of the end face 1-1 is shown in the f graph of Figure 9 . This spectral distribution curve contains the information of the end face 1 and the information of the end face 1-1. Through the spectral distribution curve, the length of the F-P cavity of the end face 1-1 and the connection relationship between the end face 1-1 and the end face 1 can be determined.

[0136] In order to determine the information of each end face step by step, the test device performs domain transformation on the wavelength-relative intensity distribution at the time domain position where the cross-correlation is located, which is closest to the test device (i.e. Δt is the smallest in Figure 6 ). The length of the F-P cavity at the time domain position is determined according to the obtained spectral distribution curve. Then, the test device performs domain transformation on the wavelength-relative intensity distribution at a larger Δt, analyzes the peaks in the obtained spectral distribution curve, and determines the upper end face having a connection relationship with the end face at the time domain position and the length of the F-P cavity at the time domain position.

[0137] In Figure 9For example, in FIG. f of FIG. 6, the spectrum distribution curve has a plurality of main- side peak combinations (one main- side peak combination includes one main peak and two side peaks). In the embodiments of the present application, the size of the granularity of one main- side peak combination is determined by the distance between the main peak and any side peak in the combination; the smaller the distance, the smaller the granularity. The scaling of the main- side peak combinations with different granularities is different. The test device finds the main- side peak combination with the smallest granularity, and determines the distance between the main peak in the main- side peak combination and any side peak in the combination as the RSF of the F-P cavity at the time domain position. Then, the test device takes the main peak in the main- side peak combination with the smallest granularity as the object, and determines the main- side peak combination with the second smallest granularity. Then, according to the distance between the main peak in the main- side peak combination with the second smallest granularity and any side peak in the combination, the length of the upper F-P cavity corresponding to the main- side peak combination is determined. Then, according to the length of the upper F-P cavity determined, the upper end face connected to the target end face is determined from the one or more upper end faces at the target end face.

[0138] 407. The test device determines the network topology according to the end face information.

[0139] In step 406, the end face information determined by the test device includes the lengths of the F-P cavities and the connection relationship between the end faces. In order to realize the marking, the lengths of the F-P cavities connected to the same optical splitter in the passive optical network are different. The different F-P cavities connected to the same optical splitter are marked by the lengths of the F-P cavities, and the topology of the passive optical network can be obtained by combining the connection relationship between the end faces (F-P cavities and non-marked end faces).

[0140] Optionally, this step can be implemented by the test device or by a network management device or the like. For example, the test device can send the end face information to the network management device, and the network management device can determine the network topology in step 408.

[0141] 408. The test device determines the network structure according to the network topology and the time domain positions of the end faces.

[0142] In step 403, the test device can determine the time domain positions of the end faces in the network according to the time domain position-relative intensity distribution under any carrier wavelength λi. After the network topology is determined in step 407, the test device can determine the network structure according to the network topology and the time domain positions of the end faces.

[0143] Optionally, step 408 can be implemented by the test device or by a network management device or the like. For example, the test device can send the time domain positions of the end faces to the network management device, and the network management device can determine the network structure in step 408.

[0144] Optionally, in step 408, the test device can determine the network structure according to the network topology and the time domain positions of the end faces.Figures 3 to 9 In the illustrated embodiment, the test signal can be a downlink data signal. The sensing signal is then the reflected signal obtained from the downlink data signal through multiple end faces in the passive optical network. When the test signal is a downlink data signal, the process by which the test device acquires the sensing signal and the cross-correlation signal can be as follows: Figure 10 As shown, the process includes:

[0145] Step 1: System initialization, complete system preparation.

[0146] Step 2: Downlink data signal generation, codebook storage, and S and S low-pass filtering.

[0147] In a passive optical network (PON), a system data signal generation module acquires the downlink data signal. This module transmits the waveform of the downlink data signal to the OLT's transmission module Tx, enabling the OLT to send the downlink data signal. The system data signal generation module can also store the downlink data signal in the form of a local codebook, denoted as S. Then, the system data signal generation module filters S to reduce the impact of noise, etc. The filtering method can be low-pass filtering, etc., and this application does not limit this to any particular method.

[0148] Step 3: The system data signal generation module can extract a portion of the data from the transmitted signal S as a local codebook and store it in the buffer of the test device, denoted as S(ti,ti+Δt).

[0149] In the embodiments of this application, the system data generation module may be part of the test equipment or a device connected to the test equipment; this application does not limit this.

[0150] Step 4: Acquire the reflected signal and store R(Δt) in a FIFO.

[0151] On the other hand, the test equipment stores the reflected signal acquired in real time into a first-in-first-out queue (FIFO), and this reflected signal is denoted as R(Δt).

[0152] Step 5: R(Δt) and S(ti,ti+Δt) are cross-correlated.

[0153] The testing equipment performs cross-correlation calculations on R(Δt) and S(ti,ti+Δt) to obtain the cross-correlation signal p. n (t i , t i +Δt).

[0154] Step 6: Repeat steps 4-5 n times.

[0155] The test device changes the Δt of the cross-correlation calculation, and based on each changed Δt, performs steps 4-5 described above to obtain n sets of cross-correlation signals. The cross-correlation signals are smoothed and denoised to obtain P(ti, ti+Δt).

[0156] Step 7: Scan ti.

[0157] The test device changes the starting time ti of the codebook S(ti, ti+Δt), and based on each changed starting time ti, performs steps 2-6 described above until the codebook covers the entire link of the passive optical network, to obtain the full-link reflection information P(0, T).

[0158] The test device can also change the carrier wavelength λi of the downstream data signal, and then perform steps 2-7 based on the changed λi to scan λi, thereby obtaining the full-link full-wavelength reflection information P(0, T; λ).

[0159] Alternatively, the test signal can also be sent by a device downstream of the network, and the test signal is transmitted through multiple facets in the network, and the transmitted signal is received by the test device. The transmitted signal received by the test device is referred to as a sensing signal. The downstream direction of the network is the direction in which the network edge connects to the user (for example Figure 1 the direction of the ONU and the ONT in FIG. 1, Figure 2a and Figure 2b the direction of the lowest-level optical splitter in FIG. 2). Alternatively, the upstream test signal can be an upstream data signal, or can also be a signal agreed upon, which is not limited in the present application.

[0160] In the embodiments of the present application, the sensing signal is transmitted in the form of an optical signal in the passive optical network. However, the test device processes signals in the form of an electrical signal. Therefore, in the process of obtaining the sensing signal, the test device can convert the obtained sensing signal in the form of an optical signal into an electrical signal (for example, when the test device is an OLT or an OTDR); or the test device can receive the converted sensing signal in the form of an electrical signal (for example, when the test device is a network device), and the present application does not limit the main body of the device that converts the sensing signal into an electrical signal (for example, it can be an optical module, an optical board card, etc.).

[0161] For each link in the passive optical network, after the test device receives the sensing signal obtained by transmitting the upstream test signal through multiple facets in the link, the test device can perform cross-correlation calculation on the test signal and the sensing signal to obtain a cross-correlation signal. Thus, the cross-correlation signal of each complete link in the passive optical network is obtained. Then, the test device multi-dimensionally fits to determine multiple facets (F-P cavities and / or non-marked facets) having the same characteristics. The multiple facets having the same characteristics are multiple lower-level facets connected to the same facet or optical splitter. Thus, the length of each F-P cavity and the connection relationship between each facet are determined from the lowest level to the upper level, and thus obtained

[0162] Optionally, the testing equipment can determine the length of each FP cavity and the distance between each end face based on the spectral distribution curves obtained after domain transformation of the wavelength-relative intensity distribution of different links. For example, starting from the lowest-level end face, if multiple lowest-level end faces are connected to the same second-lower-level end face, the difference between the spectral distribution curves of these multiple lowest-level end faces lies in the distance between the main and sub-peaks within the smallest granularity of the main and sub-peak combination. Therefore, by comparing the spectral distribution curves of these multiple lowest-level end faces, the FSR of the FP cavities of these multiple lowest-level end faces, as well as the connection between these multiple lowest-level end faces and the same second-lower-level end face, can be determined.

[0163] By eliminating the smallest granularity subpeaks from the spectral distribution curves of these multiple links, the remaining information represents the information between the second-lower-level endfaces and higher-level endfaces. Referring to the process described above for determining the FSR of the FP cavities in the second-lower-level endfaces, and the process for determining the connectivity between these endfaces, the FSR of the FP cavities in the second-lower-level endfaces and the connectivity between the endfaces can be obtained. By analogy upwards in this manner, the information of all endfaces and the connectivity between all endfaces in the entire passive optical network can be reconstructed, thus restoring the topology of the entire passive optical network.

[0164] Alternatively, the connection relationship between different end faces can also be determined using the following formula:

[0165]

[0166] Among them, S n+1 (v) represents the first distribution corresponding to the target FP cavity, that is, the wavelength-relative intensity distribution of the cross-correlation signal at the time domain location of the target FP cavity. i (v) represents the transmittance of the parent FP cavity that is connected to the target FP cavity. n+1 (v) represents the transmittance of the target FP cavity. I0 represents the emitted light intensity of the test signal. v represents the carrier frequency of the test signal, used to indicate the wavelength corresponding to the test signal.

[0167] The passive optical network and network topology determination method provided in the embodiments of this application have been described above. Next, the test equipment provided in the embodiments of this application for implementing the above network topology determination method will be described.

[0168] like Figure 11 As shown, the test device 1100 provided in this embodiment includes a transceiver unit 1101 and a processing unit 1102. The test device 1100 is... Figure 2a and Figure 2b The passive optical network shown, and Figures 3 to 10 The test equipment used in the method.

[0169] The transceiver unit 1101 is used to acquire the sensing signal obtained by the test signal through multiple end faces. The processing unit 1102 is used to determine the end face information of multiple end faces in the passive optical network based on the cross-correlation signal between the test signal and the sensing signal; the end face information is used to determine the topology of the passive optical network.

[0170] Test equipment 1100 is used to achieve Figures 3 to 10 The network topology determination method described in [the document]. Specifically, [the method is described in the document]. Figure 3 In this process, the transceiver unit is used to implement step 301, and the processing unit is used to implement step 302. Specifically... Figure 4 In this process, processing unit 1102 is used to implement steps 403 to 408. Specifically... Figure 10 In this process, the transceiver unit 1101 is used to implement step 4, and the processing unit 1102 is used to implement... Figure 10 All steps except step 4.

[0171] In one alternative implementation, the multiple end faces include multiple Fabry-Perot FP cavities. End face information includes the lengths of the multiple FP cavities and the hierarchical relationships between them.

[0172] In one optional implementation, the cross-correlation signal includes a relative intensity, which is the relative intensity of the cross-correlation peaks of the test signal and the sensing signal at different wavelengths and different time-domain locations. The processing unit 1102 is specifically used to: determine the length of the FP cavity at different time-domain locations based on the relative intensity distribution of the cross-correlation signal at different wavelengths.

[0173] In one optional implementation, the processing unit 1102 is specifically used to: determine the length of the first FP cavity at the first time-domain position based on the relative intensity distribution of the cross-correlation signal at different wavelengths. Here, the first time-domain position is the time-domain position where the cross-correlation peak in the cross-correlation signal is located.

[0174] In one optional implementation, the processing unit 1102 is specifically used to: perform domain transformation on the relative intensity distribution curve of the cross-correlation signal at a second time-domain position at different wavelengths to obtain the spectral distribution curve at the second time-domain position. Here, the second time-domain position is the time-domain position where the cross-correlation peaks in the cross-correlation signal are located. Furthermore, the length of the FP cavity at the second time-domain position is determined based on the peak spacing of the same cluster of peaks in the spectral distribution curve.

[0175] In an optional implementation, the cross-correlation signal includes a relative intensity, and the relative intensity is a relative intensity of a cross-correlation peak of the test signal and the sensing signal at different wavelengths and different time domain positions. The processing unit 1102 is specifically configured to determine the senior-junior relationship between the F-P cavities at the different time domain positions according to the relative intensity distribution of the cross-correlation signal at different wavelengths at the different time domain positions.

[0176] In an optional implementation, the processing unit 1102 is specifically configured to determine the senior F-P cavity having a connection relationship with the target F-P cavity according to the relative intensity distribution of the cross-correlation signal at different wavelengths at the time domain position where the target F-P cavity is located, and the reflectivity and / or transmissivity of the senior F-P cavity of the target F-P cavity. The time domain position where the target F-P cavity is located is the time domain position of the cross-correlation peak in the cross-correlation signal.

[0177] In an optional implementation, the relative intensity distribution of the cross-correlation signal at different wavelengths at the time domain position where the target F-P cavity is located meets the following corresponding relationship:

[0178]

[0179] wherein S n+1 (v) represents the relative intensity distribution of the cross-correlation signal at different wavelengths at the time domain position where the target F-P cavity is located, T i (v) represents the transmissivity of the senior F-P cavity having a connection relationship with the target F-P cavity, R n+1 (v) represents the reflectivity of the target F-P cavity, I0 represents the emission intensity of the test signal, and v represents the wavelength of the test signal.

[0180] In an optional implementation, the processing unit 1102 is specifically configured to perform domain transformation on the relative intensity distribution curve of the cross-correlation signal at different wavelengths at the time domain position where the target F-P cavity is located, to obtain a target spectral distribution curve corresponding to the target F-P cavity; wherein the time domain position where the target F-P cavity is located is the time domain position of the cross-correlation peak in the cross-correlation signal. And perform domain transformation on the relative intensity distribution curve of the cross-correlation signal at different wavelengths at the time domain position where the F-P cavity in the reference F-P cavity set is located, to obtain a reference spectral distribution curve set corresponding to the reference F-P cavity set; wherein the reference F-P cavity set is a set of senior F-P cavities of the target F-P cavity. And determine the spectral distribution curve information of the senior F-P cavity having a connection relationship with the target F-P cavity from the reference spectral distribution curve set according to the target spectral distribution curve, to determine the senior F-P cavity having a connection relationship with the target F-P cavity.

[0181] In an optional implementation, the test signal includes a plurality of wavelengths of test signals, and the sensing signal includes a plurality of wavelengths of sensing signals. The processing unit 1102 is further configured to determine, according to the test signal and the corresponding sensing signal of each wavelength of the plurality of wavelengths, a relative intensity distribution of the cross-correlation signal at different time domain positions under each wavelength, to obtain a relative intensity distribution of the cross-correlation signal at different time domain positions under different wavelengths.

[0182] In an optional implementation, the test signal is a downstream data signal, and the sensing signal is a reflection signal of the downstream data signal after passing through the plurality of end faces.

[0183] In an optional implementation, the transceiver unit 1101 is further configured to obtain an upstream data signal from the passive optical network, and a time point of obtaining the upstream data signal is different from a time point of obtaining the sensing signal. The processing unit 1102 is further configured to analyze the upstream data signal.

[0184] In an optional implementation, the end face further includes a target end face of a non-F-P cavity, and the cross-correlation signal includes a relative intensity, and the relative intensity is a relative intensity of a cross-correlation peak of the test signal and the sensing signal at different wavelengths and different time domain positions. The processing unit 1102 is specifically configured to determine, in a set of relative intensity distributions of the cross-correlation signal at different wavelengths and at a plurality of time domain positions, a target distribution that is isomorphic to a relative intensity distribution of the cross-correlation signal at different wavelengths and at a time domain position where the target end face is located. And determine that there is a connection relationship between the F-P cavity at the time domain position corresponding to the target distribution and the target end face.

[0185] In an optional implementation, the processing unit 1102 is further configured to determine, according to the cross-correlation signal between the test signal and the sensing signal, distances between the plurality of end faces. And determine the network structure of the passive optical network according to the distances between the plurality of end faces and the topology of the passive optical network.

[0186] In an optional implementation, the plurality of optical splitters includes N optical splitters, and the test device 1100 receives sensing signals of different wavelength bands from the N optical splitters. The test device 1100 further includes N F-P cavities corresponding to the N optical splitters one by one. The transceiver unit 1102 is specifically configured to obtain the sensing signals of different wavelength bands from the N optical splitters through the N F-P cavities.

[0187] In an optional implementation, the test device 1100 comprises an optical integrated chip; the optical integrated chip comprises a transceiver unit 1101 and an optical circulator unit. The transceiver unit 1101 comprises a first photodetector and a second photodetector. The optical circulator unit is configured to separate the upstream sensing signal from the PON and send the upstream sensing signal to the first photodetector. The first photodetector is configured to acquire the upstream sensing signal from the PON via the optical circulator unit. The second photodetector is configured to acquire the upstream data signal from the PON.

[0188] In an optional implementation, the transceiver unit 1101 comprises a photodetector configured to receive the data signal and the sensing signal from the PON at different time instants respectively. The test device 1100 further comprises a transimpedance amplifier configured to amplify the sensing signal from the photodetector according to a first gain coefficient, and amplify the data signal from the photodetector according to a second gain coefficient. The second gain coefficient is less than the first gain coefficient.

[0189] As shown in FIG. 1, Figure 12 The embodiments of the present application also provide a test device. The test device comprises:

[0190] a laser configured to send a downstream data signal of a second wavelength band. Optionally, the laser can be a distributed feedback laser (DFB).

[0191] a multiplexer (MUX) configured to receive an upstream signal from the PON and separate the upstream signal into an upstream data signal of a first wavelength band and a sensing signal of a second wavelength band.

[0192] a photodiode (PD) configured to receive the upstream data signal of the first wavelength band from the MUX.

[0193] an optical circulator configured to separate the upstream sensing signal from a second wavelength band path in the test device and send the sensing signal to a low speed PD. Optionally, the optical circulator can be configured to separate the upstream sensing signal from an optical path between the MUX and the laser and send the sensing signal to the low speed PD.

[0194] a low speed PD configured to receive the sensing signal from the optical circulator.

[0195] The test device can further include an analog-to-digital converter (ADC), a trans-impedance amplifier (TIA), a digital signal processor (DSP), an electro-absorption modulator (EAM), etc., respectively used for analog-to-digital conversion, signal amplification, data processing, signal modulation, etc.

[0196] As shown in Figure 13 The embodiments of the present application further provide a test device. The test device includes:

[0197] A first multiplexer (i.e., MUX outside the gray part in the figure) is used to combine the downstream data signal (first waveband) and the test signal (second waveband) in the downstream direction sent to the passive optical network. And separate the signal from the passive optical network in the upstream direction into the upstream data signal (first waveband) and the sensing signal (second waveband).

[0198] A first photodetector is used to receive the upstream data signal of the first waveband from the first multiplexer.

[0199] An optical circulator is used to separate the sensing signal in the upstream direction from the second waveband path in the test device, and send the sensing signal to the second photodetector.

[0200] A second multiplexer (MUX in the gray part in the figure) is used to combine the upstream data signal and the downstream data signal of the first waveband for transmission.

[0201] A laser (e.g., DFB laser in the gray part in the figure) is used to send the downstream data signal to the second multiplexer.

[0202] A low-speed laser (e.g., single mode vertical-cavity surface-emitting laser (SM-VCSEL) outside the gray part in the figure) is used to send the test signal to the first multiplexer.

[0203] An optical circulator is used to separate the sensing signal in the upstream direction from the optical path between the first multiplexer and the low-speed laser, and send the sensing signal to the low-speed photodetector.

[0204] A low-speed photodetector (low speed PD) is used to receive the sensing signal from the optical circulator.

[0205] The test device can further include an ADC, a TIA, a DSP, an EAM, etc., respectively used for realizing analog-to-digital conversion, amplification of a signal, processing of data, modulation of a signal, etc.

[0206] It is worth noting that the gray part in the figure can be the structure of an existing OLT / OTDR. The structure outside the gray part can be made into a plug-in board, i.e., the first multiplexer, the optical circulator, the low-speed laser, the low-speed photodetector, and the DSP are made into a plug-in board, which serves as a test device and realizes the functions of the test device.

[0207] As shown in Figure 14 The embodiments of the present application further provide a test device. The test device is applicable to a passive optical network including a plurality of transmission ports (i.e., port #1-port #N in the figure), and the plurality of transmission ports are used for transmitting signals of different communication wavebands. The test device includes:

[0208] A plurality of F-P cavities corresponding to the plurality of transmission ports of the passive optical network one by one.

[0209] A plurality of first multiplexers corresponding to the plurality of F-P cavities one by one. Any first multiplexer in the plurality of first multiplexers is used for receiving an upstream signal from a corresponding transmission port, and separating the upstream signal into a sensing signal of a second waveband and an upstream data signal outside the second waveband. The second waveband is different from the different communication wavebands.

[0210] A low-speed laser (SM-VCSEL in the figure) is used for transmitting a test signal of the second waveband to a second multiplexer.

[0211] The second multiplexer is used for separating the test signal of the second waveband into test signals of N wavebands, and transmitting the test signals of the N wavebands to the corresponding N first multiplexers respectively. In addition, the second multiplexer receives N waveband sensing signals from the plurality of first multiplexers. The N waveband sensing signals are reflection signals obtained by transmitting the test signals of the N wavebands through the corresponding ports in the passive optical network respectively.

[0212] An optical circulator is used for separating a sensing signal in an upstream direction from an optical path between the second multiplexer and the low-speed laser, and transmitting the sensing signal to a low-speed photodetector.

[0213] The low-speed photodetector (low speed PD) is used for receiving the sensing signal from the optical circulator.

[0214] The test device can further include an ADC, a TIA, a field programmable gate array (FPGA), an EAM, etc., respectively used for realizing analog-to-digital conversion, amplification of a signal, processing of data, modulation of a signal, etc.

[0215] Optionally, the low-speed laser can be a single-mode laser.

[0216] It is worth noting that the gray part in the upper half of the figure can be the structure of the existing OLT / OTDR. The structure of the multiple OLT / OTDRs in the upper part can be made into a plug-in board, that is, multiple F-P cavities, multiple first multiplexers, low-speed lasers, second multiplexers, optical circulators, low-speed photodetectors, and FPGAs are made into a plug-in board, which serves as a test device to realize the functions of the test device.

[0217] As shown in Figure 15 , the embodiment of the present application further provides a test device. The test device comprises an optical integrated chip.

[0218] The optical integrated chip comprises:

[0219] A multiplexer MUX is configured to receive an upstream signal from a passive optical network and separate the upstream signal into an upstream data signal of a first wavelength band and a sensing signal of a second wavelength band.

[0220] A photodetector PD (i.e., high speed PD in the figure) is configured to receive the upstream data signal of the first wavelength band from the multiplexer.

[0221] A low-speed photodetector (low speed PD) is configured to receive the sensing signal of the second wavelength band from the multiplexer.

[0222] An optical circulator unit is configured to separate the sensing signal in the upstream direction from the second wavelength band in the optical integrated chip and send the sensing signal to the low-speed photodetector.

[0223] The test device can further comprise a laser (e.g., DFB in the figure) configured to obtain a downstream signal, an ADC, a DSP, etc. Optionally, the DSP, the ADC, etc. can be integrated on an application-specific integrated circuit (ASIC), which is not limited in the present application.

[0224] Optionally, the optical integrated chip can be a silicon photonics (SiPh) chip, an indium phosphide optical integrated chip, etc., which is not limited in the present application.

[0225] As shown in Figure 16 , the embodiment of the present application further provides a test device. The test device comprises:

[0226] A laser (e.g., DFB in the figure) is configured to send a downstream data signal of a second wavelength band.

[0227] The first multiplexer (i.e., the larger MUX in the figure) is configured to receive the upstream signal from the passive optical network and separate the upstream signal into the first band upstream data signal and the second band sensing signal.

[0228] The optical circulator is configured to separate the reflected signal in the upstream direction from the optical path between the first multiplexer and the laser and send the sensing signal to the second multiplexer.

[0229] The second multiplexer (i.e., the smaller MUX in the figure) is configured to receive the upstream data signal from the first multiplexer and the sensing signal from the optical circulator.

[0230] The photodetector PD is configured to receive the upstream data signal and the sensing signal from the second multiplexer.

[0231] The transimpedance amplifier is configured to:

[0232] amplify the sensing signal from the photodetector according to a first gain coefficient.

[0233] amplify the upstream data signal from the photodetector according to a second gain coefficient, wherein the second gain coefficient is smaller than the first gain coefficient.

[0234] Optionally, the first gain coefficient and the second gain coefficient can be gain coefficients determined by manual gain control (MGC) or can be automatic gain coefficients, which are not limited in the present application.

[0235] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system, device and unit described above can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0236] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units or components shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0237] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0238] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present alone, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0239] The integrated unit, if realized in the form of a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part of the prior art that contributes to the technical solutions or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various program code storage media.

Claims

1. A network topology determination method, characterized by, The method is applied to a test device, and the method comprises: obtaining sensing signals obtained by a test signal passing through a plurality of end faces in a passive optical network; the plurality of end faces comprise input end faces and / or output end faces of a plurality of optical splitters in the passive optical network, and links between the plurality of optical splitters are in a tree topology; determining end face information of the plurality of end faces according to cross-correlation signals between the test signal and the sensing signals; the end face information is used to determine a topology of the passive optical network, and the cross-correlation signals comprise relative intensities of cross-correlation peaks of the test signal and the sensing signals at different wavelengths and different time domain positions.

2. The method of claim 1, wherein, The plurality of end faces comprise a plurality of Fabry-Perot (F-P) cavities; and the end face information comprises lengths of the plurality of F-P cavities and senior-junior relationships between the plurality of F-P cavities.

3. The method of claim 2, wherein, The determining of the end face information of the plurality of end faces according to the cross-correlation signals between the test signal and the sensing signals comprises: determining lengths of F-P cavities at the different time domain positions according to relative intensity distributions of the cross-correlation signals at the different wavelengths and the different time domain positions.

4. The method of claim 3, wherein, The determining of the lengths of the F-P cavities at the different time domain positions according to the relative intensity distributions of the cross-correlation signals at the different wavelengths and the different time domain positions comprises: determining a length of a first F-P cavity at a first time domain position according to a relative intensity distribution of the cross-correlation signals at the different wavelengths and at the first time domain position; wherein the first time domain position is a time domain position of a cross-correlation peak in the cross-correlation signals.

5. The method of claim 3, wherein, The determining of the lengths of the F-P cavities at the different time domain positions according to the relative intensity distributions of the cross-correlation signals at the different wavelengths and the different time domain positions comprises: performing domain transformation on a relative intensity distribution curve of the cross-correlation signals at the different wavelengths and at a second time domain position to obtain a spectral distribution curve at the second time domain position; wherein the second time domain position is a time domain position of a cross-correlation peak in the cross-correlation signals; determining a length of a F-P cavity at the second time domain position according to a peak interval of a same cluster of peaks in the spectral distribution curve.

6. The method according to any one of claims 2 to 5, characterized in that, The determining of the end face information of the plurality of end faces according to the cross-correlation signals between the test signal and the sensing signals comprises: determining senior-junior relationships between F-P cavities at the different time domain positions according to relative intensity distributions of the cross-correlation signals at the different wavelengths and the different time domain positions.

7. The method of claim 6, wherein, The determining of the senior-junior relationships between the F-P cavities at the different time domain positions according to the relative intensity distributions of the cross-correlation signals at the different wavelengths and the different time domain positions comprises: According to a first distribution corresponding to a target F-P cavity and reflectivity and / or transmissivity of a superior F-P cavity of the target F-P cavity, a superior F-P cavity having a connection relationship with the target F-P cavity is determined in the superior F-P cavity of the target F-P cavity; wherein the first distribution is a relative intensity distribution of the cross-correlation signal at the different wavelengths at a time domain position where the target F-P cavity is located, and the time domain position where the target F-P cavity is located is a time domain position where a cross-correlation peak in the cross-correlation signal is located.

8. The method of claim 7, wherein, The first distribution conforms to a corresponding relationship as follows: where S n+1 (v) represents the first distribution, T i (v) represents the transmissivity of the upper F-P cavity having a connection relationship with the target F-P cavity, R n+1 (v) represents the reflectivity of the target F-P cavity, I0 represents the emission light intensity of the test signal, and v represents the carrier frequency of the test signal.

9. The method of claim 6, wherein, The determination of the superior-inferior relationship between the F-P cavities at the different time domain positions according to the relative intensity distribution of the cross-correlation signal at the different wavelengths at the different time domain positions comprises: A first distribution curve corresponding to a target F-P cavity is subjected to domain transformation to obtain a target spectral distribution curve corresponding to the target F-P cavity; wherein the first distribution curve is a distribution curve of the relative intensity of the cross-correlation signal at the different wavelengths at a time domain position where the target F-P cavity is located; and the time domain position where the target F-P cavity is located is a time domain position where a cross-correlation peak in the cross-correlation signal is located; A reference distribution curve corresponding to each of at least one superior F-P cavity of the target F-P cavity is subjected to domain transformation to obtain a reference spectral distribution curve corresponding to each of the at least one superior F-P cavity; wherein the reference distribution curve is a distribution curve of the relative intensity of the cross-correlation signal at the different wavelengths at a time domain position where the corresponding superior F-P cavity is located; According to the target spectral distribution curve, a spectral distribution curve of a superior F-P cavity having a connection relationship with the target F-P cavity is determined in the reference spectral distribution curve corresponding to each of the at least one superior F-P cavity, so as to determine the superior F-P cavity having the connection relationship with the target F-P cavity.

10. The method according to any one of claims 1 to 5, characterized in that, The test signal comprises test signals at the different wavelengths, and the sensing signal comprises sensing signals at the different wavelengths; The method further comprises: According to the test signal and the corresponding sensing signal at each of the different wavelengths, a relative intensity distribution of the cross-correlation signal at the different wavelengths at the different time domain positions is determined; According to the relative intensity distribution of the cross-correlation signal at the different wavelengths at the different time domain positions, a relative intensity distribution of the cross-correlation signal at the different wavelengths at the different time domain positions is obtained.

11. The method according to any one of claims 1 to 5, characterized in that, The test signal is a downlink data signal, and the sensing signal is a reflection signal obtained after the downlink data signal passes through the plurality of end faces.

12. The method according to any one of claims 1 to 5, characterized in that, The method further comprises: An uplink data signal from the passive optical network is obtained; wherein a time point at which the uplink data signal is obtained is different from a time point at which the sensing signal is obtained; The uplink data signal is analyzed.

13. The method according to any one of claims 1 to 5, characterized in that, The plurality of end faces further comprises a target end face of a non-F-P cavity; The determination of the end face information of the plurality of end faces according to the cross-correlation signal between the test signal and the sensing signal comprises: In the set of relative intensity distributions, a target distribution isosymmetric to a relative intensity distribution corresponding to the target end face is determined; wherein the set of relative intensity distributions is a set of relative intensity distributions of the cross-correlation signals at different wavelengths respectively at a plurality of time domain positions; and the relative intensity distribution corresponding to the target end face is a relative intensity distribution of the cross-correlation signal at the different wavelengths at a time domain position where the target end face is located. It is determined that there is a connection relationship between the F-P cavity at the time domain position corresponding to the target distribution and the target end face.

14. The method according to any one of claims 1 to 5, characterized in that, Further comprising: According to the cross-correlation signal between the test signal and the sensing signal, the distances between the plurality of end faces are determined. According to the distances between the plurality of end faces and the topology of the passive optical network, the network structure of the passive optical network is determined.

15. A passive optical network, comprising: Comprising: A plurality of optical splitters, the links between the plurality of optical splitters being in a tree topology; A test device is configured to obtain sensing signals obtained by a test signal passing through a plurality of end faces, and determine end face information of the plurality of end faces according to a cross-correlation signal between the test signal and the sensing signal, the end face information being used to determine a topology of the passive optical network, the cross-correlation signal including relative intensities of cross-correlation peaks of the test signal and the sensing signal at different wavelengths and different time domain positions.

16. The network of claim 15, wherein, The test device is configured to implement the network topology determination method of any one of claims 1 to 14.

17. The network of claim 15 or 16, wherein, The plurality of end faces include a plurality of F-P cavities, and lengths of the plurality of F-P cavities connected to the same optical splitter are different from each other.

18. A test apparatus, characterized by The test device is applied to a passive optical network, the passive optical network including a plurality of optical splitters and a plurality of end faces, links between the plurality of optical splitters being in a tree topology, the plurality of end faces including input end faces and / or output end faces of the plurality of optical splitters, and the test device comprising: A transceiver unit is configured to obtain sensing signals obtained by a test signal passing through a plurality of end faces; A processing unit is configured to determine end face information of the plurality of end faces according to a cross-correlation signal between the test signal and the sensing signal, the end face information being used to determine a topology of the passive optical network, the cross-correlation signal including relative intensities of cross-correlation peaks of the test signal and the sensing signal at different wavelengths and different time domain positions.

19. The apparatus of claim 18, wherein, The plurality of end faces include a plurality of F-P cavities; and the end face information includes lengths of the plurality of F-P cavities and senior-junior relationships between the plurality of F-P cavities.

20. The apparatus of claim 19, wherein, The processing unit is specifically configured to determine lengths of the F-P cavities at the different time domain positions according to relative intensity distributions of the cross-correlation signals at the different wavelengths at the different time domain positions.

21. The apparatus of claim 20, wherein, The processing unit is specifically configured to: determine a length of a first F-P cavity at a first time domain position according to relative intensity distributions of the cross-correlation signals at the different wavelengths at the first time domain position; wherein the first time domain position is a time domain position of a cross-correlation peak in the cross-correlation signal.

22. The apparatus of claim 20, wherein, The processing unit is specifically configured to: The processing unit is specifically configured to: perform domain transformation on the relative intensity distribution curves of the cross-correlation signals at the different wavelengths at the second time domain position to obtain a spectrum distribution curve at the second time domain position; wherein the second time domain position is a time domain position of a cross-correlation peak in the cross-correlation signals. The processing unit is specifically configured to: determine a length of the F-P cavity at the second time domain position according to a peak spacing of the same cluster peaks in the spectrum distribution curve.

23. The apparatus of any one of claims 19-22, wherein, The processing unit is specifically configured to: determine a superior-inferior relationship between the F-P cavities at the different time domain positions according to the relative intensity distribution of the cross-correlation signals at the different wavelengths at the different time domain positions.

24. The apparatus of claim 23, wherein, The processing unit is specifically configured to: The processing unit is specifically configured to: determine a superior F-P cavity having a connection relationship with the target F-P cavity in the superior F-P cavities of the target F-P cavity according to the relative intensity distribution of the cross-correlation signals at the different wavelengths at the time domain position of the target F-P cavity, and reflectivity and / or transmissivity of the superior F-P cavity of the target F-P cavity; wherein the time domain position of the target F-P cavity is a time domain position of a cross-correlation peak in the cross-correlation signals.

25. The apparatus of claim 24, wherein, The relative intensity distribution of the cross-correlation signals at the different wavelengths at the time domain position of the target F-P cavity satisfies a corresponding relationship as follows: wherein S n+1 (v) represents the relative intensity distribution of the cross-correlation signal at the time-domain position where the target F-P cavity is located, T i (v) represents the transmittance of the upper F-P cavity having a connection relationship with the target F-P cavity, R n+1 (v) represents the reflectivity of the target F-P cavity, I0 represents the emission light intensity of the test signal, and v represents the carrier frequency of the test signal.

26. The apparatus of claim 23, wherein, The processing unit is specifically configured to: The processing unit is specifically configured to: perform domain transformation on the relative intensity distribution curves of the cross-correlation signals at the different wavelengths at the time domain position of the target F-P cavity to obtain a target spectrum distribution curve corresponding to the target F-P cavity; wherein the time domain position of the target F-P cavity is a time domain position of a cross-correlation peak in the cross-correlation signals. The processing unit is specifically configured to: perform domain transformation on the relative intensity distribution curves of the cross-correlation signals at the different wavelengths at the time domain positions of the F-P cavities in the reference F-P cavity set to obtain a reference spectrum distribution curve set corresponding to the reference F-P cavity set; wherein the reference F-P cavity set is a set of superior F-P cavities of the target F-P cavity. The processing unit is specifically configured to: determine spectrum distribution curve information of a superior F-P cavity having a connection relationship with the target F-P cavity from the reference spectrum distribution curve set according to the target spectrum distribution curve, so as to determine the superior F-P cavity having the connection relationship with the target F-P cavity.

27. The apparatus of any one of claims 18-22, wherein, The test signal includes test signals of multiple wavelengths, and the sensing signal includes sensing signals of the multiple wavelengths. The processing unit is further configured to: determine the relative intensity distribution of the cross-correlation signals at the different wavelengths at the different time domain positions according to the test signal and the corresponding sensing signal of each wavelength in the multiple wavelengths, to obtain the relative intensity distribution of the cross-correlation signals at the different wavelengths at the different time domain positions.

28. The apparatus of any one of claims 18-22, wherein, The test signal is a downlink data signal, and the sensing signal is a reflection signal obtained after the downlink data signal passes through the multiple end faces.

29. The apparatus of any one of claims 18-22, wherein, The transceiving unit is further configured to: acquire an uplink data signal from the passive optical network; wherein a time point of acquiring the uplink data signal is different from a time point of acquiring the sensing signal. The processing unit is further configured to: analyze the uplink data signal.

30. The apparatus of any one of claims 18-22, wherein, The end face further comprises a target end face of a non-F-P cavity; and the processing unit is specifically configured to: In the set of relative intensity distribution of the cross-correlation signals at different wavelengths at multiple time domain positions, determine a target distribution isomorphic to the relative intensity distribution of the cross-correlation signal at the time domain position where the target end face is located at different wavelengths; Determine that there is a connection relationship between the F-P cavity at the time domain position corresponding to the target distribution and the target end face.

31. The apparatus of any one of claims 18-22, wherein, The processing unit is further configured to: Determine the distance between the multiple end faces according to the cross-correlation signal between the test signal and the sensing signal; Determine the network structure of the passive optical network according to the distance between the multiple end faces and the topology of the passive optical network.

32. The apparatus of any one of claims 18-22, wherein, The multiple optical splitters comprise N optical splitters, and the sensing signals from the N optical splitters received by the test device are of different wavelength bands; The test device further comprises: N F-P cavities corresponding to the N optical splitters one by one; The transceiver unit is specifically configured to obtain the sensing signals of different wavelength bands from the N optical splitters through the N F-P cavities.

33. The apparatus of any one of claims 18-22, wherein, The test device comprises an optical integrated chip; The optical integrated chip comprises the transceiver unit and an optical ring unit; The transceiver unit comprises a first photodetector and a second photodetector; The optical ring unit is configured to separate the sensing signals in the upstream direction and send the sensing signals in the upstream direction to the first photodetector; The first photodetector is configured to obtain the sensing signals in the upstream direction from the passive optical network through the optical ring unit; The second photodetector is configured to obtain data signals in the upstream direction from the passive optical network.

34. The apparatus of any one of claims 18-22, wherein, The transceiver unit comprises a photodetector configured to receive data signals and sensing signals from the passive optical network at different time instants, respectively; The test device further comprises a transimpedance amplifier configured to: Amplify the sensing signals from the photodetector according to a first gain coefficient; Amplify the data signals from the photodetector according to a second gain coefficient; wherein the second gain coefficient is less than the first gain coefficient.

35. A computer-readable storage medium, comprising: The computer readable storage medium stores a program, and when the computer executes the program, the method in any one of claims 1-14 is executed.

36. A computer program product, characterised in that, When the computer program product is executed on the computer, the computer executes the method in any one of claims 1-14.

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