Optical communication link detection method and apparatus

Abstract

Provided in the present application are an optical communication link detection method and apparatus. An optical signal is received, wherein the optical signal is subjected to photoelectric conversion into an electrical signal; and on the basis of parameters of the electrical signal that comprise a comparison value between the highest and lowest level distributions of the electrical signal, and the characteristics of a frequency response curve of the electrical signal, information of an optical communication link can be determined, i.e., the intensity of multi-path interference (MPI) noise and / or a chirp coefficient are / is determined, such that an MPI effect and a chirp effect in the optical communication link can be detected. Thus, the impairment conditions of the optical communication link are determined, without requiring additional hardware devices, thereby achieving low cost. In addition, by means of the method, the magnitude of the influence of the MPI effect and the magnitude of the influence of the chirp effect on the optical communication link (i.e., the intensity of the MPI noise, and the chirp coefficient) can also be obtained, such that operations, such as optimizing the optical communication link, can be subsequently executed on the basis of the intensity of the MPI noise and the chirp coefficient.

Description

Optical communication link detection method and apparatus

[0001] The present application claims priority to the Chinese patent application No. 202411255608.9, filed on September 6, 2024, with the State Intellectual Property Office of China, and the Chinese patent application No. 202411255608.9 has the title of “Optical communication link detection method and apparatus”, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of communication technology, and more particularly, to an optical communication link detection method and apparatus. BACKGROUND

[0003] With the continuous development of communication technology, the interconnection distance of optical fiber is increasing, which causes a large number of optical fiber connectors on the optical communication link, resulting in an increase in the probability of damage to the optical communication link. The damage to the optical communication link can cause multi-path interference (MPI) effect or chirp effect. For example, the MPI effect in the optical communication link is mainly caused by the inevitable pollution of the end face of the optical fiber connector by pollutants. MPI can have a negative impact on the optical signal transmitted in the optical communication link and can reduce the signal quality of the optical signal. For another example, the chirp effect is mainly caused by the change of the injected current in the direct current laser. The chirp effect can change the pulse shape of the optical signal transmitted in the optical communication link, resulting in a decrease in the quality of the optical signal.

[0004] Currently, for the MPI effect, the OTDR technology is mainly used to measure the position of the dirty optical fiber end face, but this technology needs manual cleaning to reduce the end face reflection, which is relatively high in cost. For the chirp effect, special instruments and special detection circuits are mainly used for chirp detection, which is relatively high in cost. In addition, the damage to the optical communication link can also be checked by detecting the optical power, but when the optical communication link has damage causing MPI effect but the optical power is normal, it is impossible to determine that the link has multi-path interference problem, and manual link investigation is still needed, which is relatively high in cost.

[0005] Therefore, how to detect the damage in the optical communication link in a low-cost manner is a technical problem to be solved at present. SUMMARY

[0006] The present application provides an optical communication link detection method and apparatus, which can detect the damage in the optical communication link in a low-cost manner.

[0007] In a first aspect, a method for detecting an optical communication link is provided. The method comprises: receiving a first optical signal, and performing photoelectric conversion on the first optical signal to obtain a first electrical signal; determining information of the optical communication link based on a parameter of the first electrical signal, the optical communication link being used to transmit the first optical signal, the parameter of the first electrical signal comprising at least one of: a comparison value of a highest level distribution and a lowest level distribution of the first electrical signal, a frequency response curve characteristic of the first electrical signal; the information of the optical communication link comprising at least one of: an intensity of multipath interference (MPI) noise, a chirp coefficient; wherein the intensity of the MPI noise is used to measure the influence of the MPI effect on the optical communication link, and the chirp coefficient is used to measure the influence of the chirp effect on the optical communication link.

[0008] The frequency response curve characteristic of the first electrical signal comprises at least one of: a curve characteristic of a frequency response curve of the first electrical signal itself, and a curve characteristic of a frequency response curve of the equalizer compensating for the first electrical signal.

[0009] Based on the above scheme, by receiving an optical signal, the optical signal is converted into an electrical signal through photoelectric conversion, and based on a parameter of the electrical signal, the parameter of the electrical signal comprises a comparison value of a highest level distribution and a lowest level distribution of the electrical signal, and a frequency response curve characteristic of the electrical signal, information of an optical communication link can be determined, that is, the intensity of the multipath interference (MPI) noise and / or the chirp coefficient are determined, so that the MPI effect and the chirp effect in the optical communication link can be detected to understand the damage of the optical communication link, without the need for additional hardware devices, and the cost is low. In addition, through the method, the influence of the MPI effect and the chirp effect on the optical communication link (i.e., the intensity of the MPI noise and the chirp coefficient) can be obtained, so that subsequent operations such as optimizing the optical communication link can be performed according to the intensity of the MPI noise and the chirp coefficient.

[0010] In combination with the first aspect, in some implementations of the first aspect, the information of the optical communication link is determined based on the parameter of the first electrical signal, comprising: determining the intensity of the MPI noise based on the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal; and / or, determining the chirp coefficient based on the frequency response curve characteristic of the first electrical signal.

[0011] Based on the above scheme, the method can specifically determine the intensity of the MPI noise based on the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal, and / or determine the chirp coefficient based on the frequency response curve characteristic of the first electrical signal, further specifying the determination manner of the intensity of the MPI noise and the chirp coefficient, so that subsequent operations such as judging whether the link is damaged and whether the link needs to be repaired can be performed according to the intensity of the MPI noise and the chirp coefficient, without the need for additional hardware devices, and the cost is low.

[0012] In some implementations of the first aspect, according to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal, the intensity of the MPI noise is determined, including: obtaining a first corresponding relationship, the first corresponding relationship including a plurality of corresponding relationships between comparison values of a plurality of highest level distributions and lowest level distributions and intensities of a plurality of MPI noises; and according to the first corresponding relationship, determining the intensity of the multipath interference (MPI) noise corresponding to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal, the plurality of comparison values of the highest level distribution and the lowest level distribution including the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal.

[0013] Based on the above scheme, by obtaining the corresponding relationship between the plurality of comparison values of the highest level distribution and the lowest level distribution and the intensities of the plurality of MPI noises, the intensity of the MPI noise corresponding to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal can be quickly and accurately determined, and no additional equipment is needed, which is low in cost.

[0014] In some implementations of the first aspect, the comparison value of the highest level distribution and the lowest level distribution includes at least one of a standard deviation difference value of the highest level distribution and the lowest level distribution, a standard deviation ratio value of the highest level distribution and the lowest level distribution, a variance difference value of the highest level distribution and the lowest level distribution, or a variance ratio value of the highest level distribution and the lowest level distribution.

[0015] Based on the above scheme, the intensity of the MPI noise can be determined according to any one or more of the standard deviation difference value of the highest level distribution and the lowest level distribution, the standard deviation ratio value of the highest level distribution and the lowest level distribution, the variance difference value of the highest level distribution and the lowest level distribution, or the variance ratio value of the highest level distribution and the lowest level distribution, so that the determination of the intensity of the MPI noise is more flexible. In addition, since the multi-level has monotonicity, the comparison value of the highest level distribution and the lowest level distribution can better reflect the amplitude of the level, so as to obtain a more accurate intensity of the MPI noise.

[0016] In some implementations of the first aspect, the first corresponding relationship is obtained by simulation of an optical communication link simulation system, and the optical communication link simulation system is used to simulate the MPI effect in the optical communication link.

[0017] Based on the above scheme, the MPI effect in the optical communication link is simulated by simulation, so as to obtain the first corresponding relationship, that is, the corresponding relationship between the plurality of comparison values of the highest level distribution and the lowest level distribution and the intensities of the plurality of MPI noises, so that the intensity of the MPI noise corresponding to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal determined by using the first corresponding relationship is more accurate.

[0018] In some implementations of the first aspect, according to the frequency response curve feature of the first electrical signal, the chirp coefficient is determined by: obtaining a second correspondence relationship, the second correspondence relationship including a plurality of frequency response curve features and a plurality of chirp coefficients; and determining the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal according to the second correspondence relationship, the plurality of frequency response curve features including the frequency response curve feature of the first electrical signal.

[0019] Based on the above scheme, by obtaining the correspondence relationship between the plurality of frequency response curve features and the plurality of chirp coefficients, the chirp coefficient matching the frequency response curve feature of the first electrical signal can be quickly and accurately determined, and no additional equipment is needed, which is low in cost.

[0020] In some implementations of the first aspect, the method further includes: receiving a second optical signal and performing photoelectric conversion on the second optical signal to obtain a second electrical signal, the first optical signal corresponding to a first time, the second optical signal corresponding to a second time, the second time being after the first time; and determining whether the optical communication link has chirp degradation according to a frequency response curve feature of the second electrical signal and a frequency response curve feature of the first electrical signal, the optical communication link also being used to transmit the second optical signal.

[0021] The first optical signal and the second optical signal are the same optical signal sent by the sending device at different times. The frequency response curve feature of the second electrical signal includes at least one of the following: a curve feature of a frequency response curve of the second electrical signal itself, and a curve feature of a frequency response curve of the equalizer compensating for the second electrical signal.

[0022] Based on the above scheme, the second optical signal is received after the first optical signal, and is photoelectrically converted into the second electrical signal. According to the frequency response curve features of the first electrical signal and the second electrical signal, it can be determined whether the optical communication link transmitting the first optical signal and the second optical signal has chirp degradation. It can be understood that at different times, the same optical signal sent by the sending end is received. When the optical communication link is damaged during this period of time, the same optical signal will be affected by the damage of the optical communication link, so that the frequency response curve features of the electrical signals corresponding to the optical signals received at different times are different. According to the different frequency response curve features, it can be determined whether the optical communication link has chirp degradation. No additional equipment is needed, which is low in cost.

[0023] With reference to the first aspect, in some implementations of the first aspect, the method further includes: determining, according to the second correspondence, a chirp coefficient corresponding to a frequency response curve feature of the second electrical signal, the plurality of frequency response curve features including the frequency response curve feature of the second electrical signal; and determining, according to the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal and the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal, whether the optical communication link has chirp degradation.

[0024] Based on the above scheme, the method can further determine the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal through the second correspondence, and determine whether the optical communication link has chirp degradation according to the chirp coefficients of the two electrical signals obtained at the two time points, without the need for additional equipment, thereby reducing costs.

[0025] With reference to the first aspect, in some implementations of the first aspect, when the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal is greater than the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal, the optical communication link has chirp degradation.

[0026] Based on the above scheme, by comparing the chirp coefficients of the two electrical signals obtained at the two time points, when the chirp coefficient of the electrical signal at the latter time point (i.e., the second electrical signal) is greater than the chirp coefficient of the electrical signal at the former time point (i.e., the first electrical signal), it can be determined that the optical communication link transmitting the first optical signal and the second optical signal has chirp degradation, without the need for additional equipment, thereby reducing costs.

[0027] With reference to the first aspect, in some implementations of the first aspect, the method further includes: determining, according to the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal and the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal, a chirp degradation value, the chirp degradation value being used to measure a degree of the chirp degradation.

[0028] Based on the above scheme, the method can further measure the degree of the chirp degradation through a chirp degradation value, which not only can measure the chirp degradation without the need for additional equipment, thereby reducing costs, but also can quantify the chirp degradation, thereby facilitating subsequent operations such as optimizing the optical communication link according to the chirp degradation value.

[0029] With reference to the first aspect, in some implementations of the first aspect, the frequency response curve feature includes at least one of the following: information of a stationary point of a frequency response curve, information of a slope between stationary points of a frequency response curve, a degree of curvature of a frequency response curve, and position information of a concave-convex part of a frequency response curve.

[0030] Based on the above scheme, the method can specifically determine the chirp coefficient according to one or more of the stationary point information of the frequency response curve, the slope information between the stationary points of the frequency response curve, the bending degree of the frequency response curve, and the position information of the concave-convex part of the frequency response curve, so that the determination manner of the chirp coefficient is more flexible.

[0031] In combination with the first aspect, in some implementations of the first aspect, the second correspondence is obtained by simulation of an optical communication link simulation system configured to simulate the chirp effect in the optical communication link.

[0032] Based on the above scheme, the chirp effect in the optical communication link is simulated in a simulated manner, so that the second correspondence is obtained, that is, the correspondence between the plurality of frequency response curve characteristics and the plurality of chirp coefficients can be accurately obtained, so that the chirp coefficient corresponding to the frequency response curve characteristic of the first electrical signal or the chirp coefficient corresponding to the frequency response curve characteristic of the second electrical signal determined by using the second correspondence is more accurate.

[0033] In a second aspect, an apparatus is provided. The apparatus is configured to perform the method of the first aspect and any of its implementations. Specifically, the apparatus includes a processor and a memory configured to store a computer program; the processor is configured to invoke and run the computer program from the memory, so that the apparatus performs the method of the first aspect and any of its implementations.

[0034] In an implementation, the apparatus is a receiving device. When the apparatus is a receiving device, the transceiving unit can be a transceiver, or an input / output interface. The processing unit can be at least one processor. Optionally, the transceiver can be a transceiving circuit. Optionally, the input / output interface can be an input / output circuit.

[0035] In another implementation, the apparatus can be a chip, a chip system, or a circuit in a receiving device. At this time, the transceiving unit can be an input / output interface, an interface circuit, an output circuit, an input circuit, a pin, or a related circuit on the chip, the chip system, or the circuit; the processing unit can be at least one processor, a processing circuit, or a logic circuit, etc.

[0036] In a third aspect, a computer readable storage medium is provided. The computer readable storage medium stores a computer program, which, when executed, causes the method of any of the implementations of the first aspect to be performed.

[0037] In a fourth aspect, a computer program product containing instructions is provided. When the computer program product is executed, the method provided by any of the implementations of the first aspect is performed.

[0038] In a fifth aspect, a chip is provided, which includes a processor and an interface. The processor reads instructions through the interface, and executes the method provided in any of the implementation manners of the first aspect.

[0039] Optionally, as an implementation manner, the chip further includes a memory, which stores a computer program or instructions. The processor is configured to execute the computer program or instructions stored in the memory, and when the computer program or instructions are executed, the processor is configured to execute the method provided in any of the implementation manners of the first aspect.

[0040] In a sixth aspect, a computer program is provided. When the computer program is executed, the method provided in any of the implementation manners of the first aspect is executed.

[0041] In a seventh aspect, a system is provided, which includes the device of the second aspect.

[0042] The possible designs and beneficial effects of the second aspect to the seventh aspect can be referred to the description of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0043] FIG. 1 is a networking schematic diagram of an optical power detection scheme.

[0044] FIG. 2 is a schematic diagram of an optical communication scenario suitable for the embodiments of the present application.

[0045] FIG. 3 is a schematic flowchart of an optical communication link detection method 300 provided by the present application.

[0046] FIG. 4 is a schematic diagram of a structure of an optical communication link simulation system.

[0047] FIG. 5 is a schematic diagram of an optical communication link and MPI effect in the optical communication link.

[0048] FIG. 6 is a schematic diagram of a difference value / ratio of standard deviations of a highest level distribution and a lowest level distribution under different intensities of MPI noise.

[0049] FIG. 7 is a frequency response curve under different line width enhancement factors a (alpha).

[0050] FIG. 8 is a frequency response curve of an LMS equalizer under different chirp coefficients.

[0051] FIG. 9 is a schematic block diagram of an optical communication link detection device 1000 provided by the embodiments of the present application.

[0052] FIG. 10 is a schematic block diagram of an optical communication link detection device 2000 provided by the embodiments of the present application.

[0053] FIG. 11 is a schematic block diagram of a chip system 3000 provided by the embodiments of the present application. DETAILED DESCRIPTION

[0054] In order to facilitate the understanding of the embodiments of the present application, the following points are first explained.

[0055] I. In the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0056] II. In the embodiments of the present application, unless otherwise specified and there is no logical conflict, the terms and / or descriptions between different embodiments are consistent and can be mutually referred to, and the technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0057] III. In the embodiments of the present application, "first", "second", and various numerical numbers (for example, "#1", "#2", etc.) are only for the convenience of description and do not limit the scope of the embodiments of the present application. The size of the serial number of each process below does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. It should be understood that the objects thus described can be interchanged under appropriate circumstances, so as to be able to describe schemes other than the embodiments of the present application. In addition, in the embodiments of the present application, the word "S310" and the like are only for the convenience of description and are not limited to the order of execution steps.

[0058] At the same time, any embodiment or design scheme described as "exemplary" or "for example" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the use of "exemplary" or "for example" and the like is intended to present the relevant concept in a specific manner for understanding.

[0059] IV. The terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0060] V. The "storage" or "saving" involved in the present application can refer to saving in one or more memories. The one or more memories can be separately provided or integrated in the encoder or decoder, processor, or device. The one or more memories can be partially separately provided and partially integrated in the decoder, processor, or device. The type of memory can be any form of storage medium, which is not limited.

[0061] Sixthly, in the embodiments of the present application, "in the case of", "when", "if" can be used interchangeably, and it should be pointed out that the meanings expressed are consistent when the distinction is not emphasized.

[0062] Seventhly, in the present application, unless otherwise specified, " / " represents that the objects before and after are in an "or" relationship, for example, A / B can represent A or B; "and / or" in the present application is only a description of the association between the objects, which means that there can be three relationships, for example, A and / or B, which can represent three cases: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural.

[0063] For the convenience of understanding, the terms involved in the embodiments of the present application are briefly described below.

[0064] I. Pulse amplitude modulation (PAM)-4

[0065] PAM-4 is a modulation technology that uses four levels for signal transmission. Each symbol period of a PAM-4 signal can represent 2-bit logical information (such as 00, 01, 10, 11).

[0066] Compared with non-return-to-zero (NRZ) modulation technology, the transmission capacity of PAM-4 signal is twice that of NRZ signal, which can significantly improve the transmission efficiency of the signal.

[0067] II. MPI in optical communication link

[0068] With the continuous development of communication technology, the interconnection distance of optical fibers increases, especially in the centralized radio access network (CRAN) scenario, the interconnection distance of optical fibers between the base-band unit (BBU) and the remote radio unit (RRU) / active antenna unit (AAU) can be as high as 10 km, and there are devices such as multiplexers, optical cross-connections, optical distribution frames (ODF) in the optical communication link, which makes it necessary to connect these devices through optical fiber cables with a large number of optical fiber connectors in order to facilitate long-distance optical signal transmission. The increase in the number of optical fiber connectors increases the number of nodes that need to be maintained in the optical fiber system, which also means that the number of nodes that fail increases, and the probability of damage to the optical communication link increases, and the damage to the optical communication link can cause MPI effect.

[0069] With time, the fiber end faces of the fiber connectors will inevitably be contaminated by contaminants. Among them, at least one new transmission path will be formed between any two contaminated fiber end faces. As the number of contaminated fiber end faces accumulates, a large number of new transmission paths will be formed inside the fiber system. The optical signals transmitted along the new transmission paths are a kind of noise to the optical signals transmitted along the main path (without reflection, direct transmission), which will affect the signal quality of the optical signals, and this phenomenon is called MPI effect.

[0070] Currently, OTDR technology is mainly used to measure the position of the contaminated fiber end face. By inputting a pulse signal (hereinafter referred to as "sending signal") into the fiber link, if the pulse signal is reflected when it passes through a fiber connector with strong reflection during transmission in the fiber, a part of the energy of the pulse signal will be reflected, and the reflected signal (hereinafter referred to as "reflected signal") can be detected at the sending end. Because the position of the connector in the fiber link is different, the OTDR technology can determine the distance of the abnormal reflection point from the sending end by measuring the time delay between the reflected signal and the sending signal at the sending end, so as to measure the position of the abnormal (such as contaminated) fiber connector. However, this technology needs manual cleaning to reduce end reflection and reduce MPI effect, which will result in high labor cost, and the current ongoing business of the optical communication system needs to be interrupted during the detection of abnormalities, and real-time MPI detection cannot be realized.

[0071] III. Chirp effect in optical communication link

[0072] Chirp refers to the instantaneous frequency change of an optical pulse in the time domain. This change can be caused by the interaction between the optical pulse and the fiber medium (such as dispersion and nonlinear effects) when the optical pulse is transmitted in the fiber. Chirp can be linear (i.e. frequency changes linearly with time) or nonlinear (i.e. frequency changes nonlinearly with time). A wave whose instantaneous frequency changes with time is called a chirp wave. If the frequency increases with time, the low-frequency wave appears first and then the high-frequency wave, that is, the rising edge of the optical pulse is low frequency and the falling edge is high frequency, it is called positive chirp or up-chirp; on the contrary, the rising edge of the optical pulse is high frequency and the falling edge is low frequency, it is called negative chirp or down-chirp.

[0073] The aforementioned optical communication link impairments can also cause chirp. Chirp refers to the phenomenon where the frequency of an optical signal changes over time. Chirp can occur in various situations. For example, in a directly modulated laser, changes in the injected current lead to changes in carrier concentration, which in turn affects the refractive index of the laser's active layer, causing the phase of the optical field to change over time, ultimately resulting in a change in the frequency of the optical signal. Chirp can be positive, for example, in the case of ultrashort pulses, where material dispersion can be used to control pulse compression and broadening. However, chirp can also be negative, especially in long-distance, high-speed optical fiber communication. When optical signals propagate through the fiber, the different group velocities of different frequencies cause changes in the shape of the information-carrying pulse, limiting the effective transmission distance of the pulse—a manifestation of chirp degradation.

[0074] Currently, chirp detection is mainly performed using instruments. For example, a network analyzer measures the frequency response curve of the optical signal before and after passing through a dispersive medium, as well as the position information of its resonant peak, to detect the chirp coefficient of the optical signal. The chirp coefficient is a parameter used to describe the chirp of a light source; it reflects the frequency change caused by modulation during the leading and trailing edges of the light pulse emitted by the optical transmitter. It includes the linewidth enhancement factor, adiabatic chirp parameters, etc. Alternatively, the chirp coefficient of an optical signal can be measured using dedicated and complex detection circuits. These methods require specialized instruments and circuits, which are not only costly but also cannot perform real-time chirp detection.

[0075] Furthermore, regarding the loss caused by damage to the optical communication link, methods based on optical power can be used to detect the optical power in the link. When the optical attenuation in the link is excessive, it can be roughly determined that the link is damaged, for example, there is a possibility that dirt on the connectors is causing excessive optical attenuation. The basis for this judgment is as follows:

[0076] 1. Optical power loss is commonly used to represent optical attenuation in an optical communication link. When the optical power loss is too large and exceeds the theoretical loss value, that is, when the actual optical power loss value under the condition of optical communication link damage / abnormality is greater than the expected theoretical line optical attenuation value, it can be roughly judged that there is damage to the optical communication link.

[0077] Fig. 1 is a networking diagram of an optical power detection scheme. As shown in Fig. 1, the optical power transmitted by a sending end (Tx) is denoted as Tx, and the optical signal is transmitted in the link shown in the figure, and the normal splice loss value is 0.25 dBm. Therefore, the optical signal reaches a receiving end (Rx) through two optical crossboxes, and the theoretical optical power received by the receiving end is denoted as Rx = Tx - 0.25 x 2, that is, the expected theoretical line optical attenuation value is 0.5 dBm. If there is an abnormality in the link, or in other words, if there is damage in the link, abnormal loss will occur. As shown in Fig. 1, the abnormal splice loss is 1.5 dBm, and the optical power received by the receiving end is Rx = Tx - (1.5 + 0.25), that is, the actual optical power loss value is 1.75 dBm, which is greater than the expected theoretical line optical attenuation value 0.5 dBm. Therefore, it can be roughly judged that the optical communication link is damaged.

[0078] 2. The optical power loss value of the uplink transmission and the optical power loss value of the downlink transmission on the optical communication link can also be compared to determine whether the optical communication link is damaged. When the uplink and downlink loss values differ greatly, it can be roughly judged that the optical communication link is damaged.

[0079] However, the calculation of the theoretical line optical attenuation value has a large error problem. Because the optical communication link is affected by many factors such as environment in actual operation, the theoretical line optical attenuation value will deviate, which makes the detection of the damage of the optical communication link inaccurate. In addition, when the optical communication link is damaged to cause MPI effect but the optical power is normal, it cannot be judged that the link has a multipath interference problem, and manual link troubleshooting is still needed, which is high in cost.

[0080] Therefore, how to detect the damage in the optical communication link in a low-cost manner is a technical problem to be solved at present.

[0081] Therefore, how to detect the damage in the optical communication link in a low-cost manner is a technical problem to be solved at present.

[0082] The technical solutions in the present application will be described below with reference to the accompanying drawings.

[0083] FIG. 2 is a schematic diagram of an optical communication scenario applicable to embodiments of the present application. With the development of communication technology, the base station architecture evolves from a distributed radio access network (DRAN) to a centralized radio access network (CRAN). FIG. 2 shows a fronthaul link scenario in the CRAN networking mode. The fronthaul link mainly refers to the connection between an AAU and a BBU. As shown in FIG. 2, the AAU can include an optical module, which is a radio frequency module for transmitting communication signals outdoors; and the BBU can also include an optical module, which is located in a central office (CO) in a house / building. The optical module is composed of optoelectronic devices, functional circuits, etc., and is used for photoelectric conversion in a fiber optic communication system. The optoelectronic devices of the optical module include both the transmitting and receiving parts. The transmitting end (Tx) converts the electrical signals to be transmitted into optical signals suitable for transmission onto the optical fiber link, and the receiving end (Rx) converts the received optical signals into electrical signals output to the receiving device, thereby achieving the purpose of data information transmission. A plurality of base stations with radio frequency modules can be connected to the central office through the optical distribution box and the backbone optical cable. In order to achieve efficient data transmission between the AAU and the BBU, the AAU and the BBU are connected by optical fibers. Any path of the connection is an optical communication link (or referred to as an "optical fiber link" or an "optical link"). The optical distribution box and other devices (not shown in the figure) included in the optical communication link can be connected by optical fiber connectors / optical fiber joints (not shown in the figure). In the present application, the AAU can transmit optical signals to the BBU through the optical communication link in FIG. 2, and the BBU can also transmit optical signals to the AAU through the optical communication link in FIG. 2. Both the AAU and the BBU can act as receiving devices to receive optical signals.

[0084] It should be noted that the above optical communication scenario is only an example. It can be understood that the present application can be applicable not only to the above-mentioned fronthaul link optical communication scenario, but also to other optical communication scenarios, which are not limited in the present application.

[0085] FIG. 3 is a schematic flowchart of an optical communication link detection method 300 provided by the present application. The method shown in FIG. 3 can be executed by a transmitting device and a receiving device, or by modules and / or devices (such as chips or integrated circuits, etc.) with corresponding functions installed in the transmitting device and the receiving device, which are not limited. In the following, the transmitting device and the receiving device are taken as examples for description. As shown in FIG. 3, the method includes:

[0086] S310, the transmitting device transmits a first optical signal to the receiving device, and correspondingly, the receiving device receives the first optical signal from the transmitting device.

[0087] In an implementation, the transmitting device modulates information onto a first optical signal, which is transmitted to a receiving device over an optical communication link. Correspondingly, the receiving device receives the first optical signal from the transmitting device over the optical communication link. In other words, the optical communication link is used to transmit the first optical signal.

[0088] Exemplarily, the transmitting device converts information into an electrical signal, and then converts the electrical signal into the first optical signal through electro-optical conversion, and finally transmits the first optical signal through the first communication link.

[0089] S320, the receiving device performs photoelectric conversion on the first optical signal to obtain a first electrical signal.

[0090] The first electrical signal corresponds to a first electrical level distribution, and the first electrical level distribution includes a highest electrical level distribution and a lowest electrical level distribution.

[0091] Specifically, after receiving the first optical signal, the receiving device can obtain the first electrical signal through photoelectric conversion, and the first electrical signal carries the information modulated into the first optical signal by the transmitting device. By sampling and measuring the first electrical signal in real time, the level of each sampling point or time point obtained is recorded, and the distribution formed by these recorded levels is the first electrical level distribution, and the first electrical level distribution includes multiple levels.

[0092] In one way, the receiving device can measure the first electrical signal multiple times to obtain multiple first electrical level distributions corresponding to the first electrical signal, i.e., multiple highest electrical level distributions and multiple lowest electrical level distributions.

[0093] It can be understood that, due to the accuracy of the measurement tool, the slight changes of the environment, etc., the result of a single measurement cannot completely and accurately reflect the electrical level distribution of the first electrical signal. Therefore, in order to obtain a more accurate electrical level distribution of the first electrical signal, the first electrical signal can be measured multiple times to reduce random errors and improve the confidence of the measurement result.

[0094] In multi-level modulation, an electrical signal is divided into multiple different amplitude levels, which are referred to as electrical levels. Each electrical level represents a specific amplitude value that the signal can take. Among these electrical levels, the highest electrical level is the one with the largest amplitude, and the lowest electrical level is the one with the smallest amplitude. The highest electrical level distribution and the lowest electrical level distribution respectively refer to the amplitude value distribution of the data points corresponding to the theoretical highest electrical level and the lowest electrical level in the actually received electrical signal. These distributions reflect the amplitude fluctuations of the electrical signal due to noise, interference, etc.

[0095] Taking a PAM-4 modulation and demodulation format as an example, the first electrical signal can be a PAM-4 signal. The PAM-4 modulation maps an input digital signal (for example, a binary bit stream) onto four levels of the PAM-4, and each symbol period can represent 2-bit logical information (such as 00, 01, 10, and 11). Exemplarily, the four levels can be represented as -3, -1, +1, and +3 (the unit can be volt or other appropriate electrical unit), which correspond to the four binary combinations of 00, 01, 10, and 11, respectively. Among them, the +3 level is the highest level, and the -3 level is the lowest level. According to the mapped symbol, a corresponding pulse signal is generated, and the pulse signal has a fixed width in time (that is, a symbol period), but the amplitude of the pulse signal depends on the mapped level value.

[0096] It can be understood that, in signal processing and data communication, although each level is defined as an accurate theoretical value when modulating, due to the influence of channel noise, system nonlinearity and other factors, the electrical signal level actually received by the receiving device will fluctuate around the theoretical value. Therefore, in the received first electrical signal, the data points corresponding to the highest level (for example, the +3 level) will form a level distribution fluctuating around the theoretical value, that is, a highest level distribution; similarly, the data points corresponding to the lowest level (for example, the -3 level) will also form a similar distribution, that is, a lowest level distribution.

[0097] S330, according to the parameter of the first electrical signal, determining information of an optical communication link used for transmitting the first optical signal; the parameter of the first electrical signal includes at least one of the following: a comparison value of the highest level distribution and the lowest level distribution of the first electrical signal, a frequency response curve feature of the first electrical signal; the information of the optical communication link includes at least one of the following: an intensity of multipath interference (MPI) noise, a chirp coefficient; wherein the intensity of the MPI noise is used to measure the influence of the MPI effect on the optical communication link, and the chirp coefficient is used to measure the influence of the chirp effect on the optical communication link.

[0098] The frequency response curve feature of the first electrical signal includes at least one of the following: a curve feature of a frequency response curve of the first electrical signal itself, and a curve feature of a frequency response curve of the equalizer compensating for the first electrical signal.

[0099] In one way, according to the parameter of the first electrical signal, the information of the optical communication link is determined, including: according to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal, the intensity of the MPI noise is determined; and / or, according to the frequency response curve feature of the first electrical signal, the chirp coefficient is determined.

[0100] In one manner, the intensity of the MPI noise is determined according to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal, comprising: obtaining a first correspondence relationship, the first correspondence relationship comprising a plurality of correspondence relationships between comparison values of highest level distribution and lowest level distribution and intensities of a plurality of MPI noises; and determining, according to the first correspondence relationship, the intensity of the multipath interference (MPI) noise corresponding to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal, the comparison value of the highest level distribution and the lowest level distribution comprising the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal.

[0101] In one manner, the first correspondence relationship is obtained by simulation of an optical communication link simulation system simulating the MPI effect in the optical communication link.

[0102] The principle of determining the intensity of the MPI noise by using the comparison value of the highest level distribution and the lowest level distribution is given below.

[0103] First, a basic mathematical model of MPI is given. The electric field of the optical signal emitted by the laser can be expressed as follows:

[0104] where ω0 is the center frequency of the optical carrier; is the laser phase noise; P sig (t) is the light-emitting power, which contains the amplitude modulation information. Amplitude modulation is a modulation technique that converts the amplitude change of a modulation signal into the amplitude change of a carrier signal, thereby realizing signal transmission. The modulation signal is the original signal carrying information, such as the first electrical signal in the above description; the carrier signal is a high-frequency signal that does not carry information itself and is used to carry the information of the modulation signal in the modulation process. The carrier signal is usually a sine wave or a cosine wave, and the amplitude of the carrier signal changes according to the change of the modulation signal.

[0105] The electric field of the optical signal after the MPI effect can be expressed as follows:

[0106] where τ ij represents the time delay of the reflection path formed by the ith reflection point and the jth reflection point relative to the original signal, and N is the total number of reflection points. It can be seen that after the MPI effect, the electric field of the optical signal increases by the term after the plus sign, and therefore the value calculated by the latter term can be used to represent the intensity of the MPI noise, i.e., the size of the MPI effect on the optical signal. After detection by an intensity modulation and direct detection (IMDD) system, the obtained current is expressed as follows:

[0107] where n(t) is white noise including the thermal noise of the receiver, R i and R j are the reflectivities of the ith and jth junctions, respectively, and the high-order term components greater than the second reflection are so small that they can be ignored. According to the above formula (3), the intensity of the MPI noise is proportional to the signal amplitude, which is expressed by the following formula:

[0108] It can be seen that the greater the amplitude of the level, the greater the intensity of the MPI noise generated. The amplitude variation of the level can be represented by the standard deviation / variance of the distribution of the highest level and the lowest level through statistical analysis. Since the intensity of the MPI noise changes with the degree of alignment of the polarization state, the application adopts a simulation modeling method to establish the correlation between the intensity of the MPI noise and the comparison value of the distribution of the highest level and the lowest level, so as to obtain a feature relationship library for storing the corresponding relationship between the intensity of the MPI noise and the comparison value of the distribution of the highest level and the lowest level, which facilitates the subsequent receiving device to determine the corresponding intensity of the MPI noise according to the comparison value of the distribution of the highest level and the lowest level.

[0109] In one possible way, the comparison value of the distribution of the highest level and the lowest level includes at least one of the following: the difference between the standard deviation of the distribution of the highest level and the standard deviation of the distribution of the lowest level, the ratio of the standard deviation of the distribution of the highest level to the standard deviation of the distribution of the lowest level, the difference between the variance of the distribution of the highest level and the variance of the distribution of the lowest level, and the ratio of the variance of the distribution of the highest level to the variance of the distribution of the lowest level.

[0110] It should be noted that the comparison value of the distribution of the highest level and the lowest level referred to in the application refers to a value obtained by comparing the distribution of the highest level with the distribution of the lowest level. The value obtained by comparison can be represented by any of the values listed above (such as the difference / ratio of the standard deviation). That is, the comparison value of the distribution of the highest level and the lowest level in the application can be any of the values listed above, or the difference / ratio of the value obtained by other operations on the distribution of the highest level and the distribution of the lowest level. The operation method is not limited to the standard deviation operation and the variance operation described above. In addition, the comparison value is not limited to the difference / ratio, but can also be other forms of values, such as the difference / ratio multiplied by a coefficient, the difference / ratio raised to a power, etc., without limitation.

[0111] The construction of the optical communication link simulation system and the detection and quantification of the intensity of the MPI noise in the optical communication link will be described in detail below. It should be noted that quantifying the intensity of the MPI noise in the optical communication link means using a quantity / value to measure the size of the influence of the MPI effect on the optical communication link.

[0112] Step one, obtaining the correspondence between the comparison values of the plurality of highest level distributions and the lowest level distributions and the intensity of the plurality of MPI noises through the end-to-end simulation of the optical communication link to construct a signal transmission model, the system is called an optical communication link simulation system, which can simulate the MPI effect in the optical communication link. The correspondence between the comparison values of the plurality of highest level distributions and the lowest level distributions and the intensity of the plurality of MPI noises is an example of the first correspondence.

[0113] It should be noted that the first correspondence can be obtained by the simulation system of the receiving device itself, or can be obtained by other devices and sent to the receiving device, which is not limited in the present application.

[0114] Among them, the optical communication link simulation system covers as many parameters and devices involved in the optical communication link as possible.

[0115] FIG. 4 is a schematic diagram of the structure of the optical communication link simulation system. The optical communication link in FIG. 4 is taken as an example of a wireless CRAN / DRAN front-end optical communication link, as shown in FIG. 4, the devices included in the optical communication link simulation system and the main functions corresponding to the devices are as follows:

[0116] 1. Sequence generation module: mainly used for generating pseudo-random binary sequence (PRBS) and custom sequence. In a wireless communication system, PRBS can be used to simulate and test the influence of MPI effect on signal transmission.

[0117] 2. Tx optical digital signal processor (oDSP): the sending end part of the oDSP chip, which is part of the optical module, is mainly responsible for digital signal processing of electrical signals before optical signal transmission. It optimizes signal quality by encoding, modulating, filtering, equalizing, etc. Processing ensures that the signal can maintain high efficiency, stability and reliability during transmission. In the simulation of the optical communication system, the generated PRBS series can be Gray coded and PAM-4 modulated, wherein Gray coding is a binary coding method, and the two adjacent values in Gray coding only differ by one bit.

[0118] 3. Digital-to-analog converter (DAC): mainly used for converting digital signals to analog signals. The converter can convert the digital signal modulated by the Tx oDSP to an analog signal for transmission and processing. The quantization bit number, sampling rate and band limiting effect in the DAC have important functions in the signal transmission process.

[0119] The number of quantization bits determines the resolution of the DAC, i.e. the smallest analog quantity that the DAC can distinguish. The higher the number of quantization bits, the more analog values the DAC can produce, and the higher the accuracy. The number of quantization bits is usually expressed in bits, such as 8 bits, 12 bits, etc. In a DAC, quantization is the process of mapping discrete values in a digital signal to continuous values in an analog signal. The number of quantization bits determines the degree of precision of this mapping. For example, an 8-bit DAC can produce 8 2 = 256 different analog levels.

[0120] The sampling rate refers to the sampling frequency of the digital signal input to the DAC, i.e. the number of samples per second (SPS). The sampling rate determines the signal bandwidth that the DAC can handle and the degree of distortion of the output signal. In digital signal processing, sampling is the process of converting a continuous-time signal into a discrete-time signal. The higher the sampling rate, the more data points are collected in the same time period, allowing the original signal to be more accurately restored.

[0121] The band-limited effect refers to the influence of the bandwidth limitation of the DAC on the conversion process, resulting in attenuation or distortion of the output signal at high frequencies.

[0122] 4. Resampling module: can be used for upsampling and filtering of the analog signal converted by the DAC.

[0123] 5. Driver: the driver can be used to provide the required output voltage. It also has a gain adjustment function to adjust the amplitude of the output signal. It can also process the peak-to-average ratio of the signal, which is the ratio of the peak power to the average power of the signal, an important indicator of the degree of signal fluctuation.

[0124] 6、Laser: It can be equipped with directly modulated laser (DML), which modulates the phase and amplitude of laser by directly injecting current. It can also be equipped with mach-zehnder modulator (MZM), which is an external modulation technique, by changing the material refractive index of one of the two waveguides, the optical signals on the two lines are different in phase at the intersection point, so as to carry out phase modulation. Laser can be used to set the wavelength of laser, output optical power, extinction ratio, relative intensity noise (RIN), line width of laser, chirp coefficient, bias point. Among them, the extinction ratio refers to the ratio of the optical power of the laser when transmitting full "1" code to the optical power when transmitting full "0" code; RIN refers to the power noise normalized to the average power, which is an important form of laser noise; the line width of the laser refers to the width of its output spectrum, which is usually expressed by frequency or wavelength; the bias point refers to the setting value of the driving current or voltage of the laser when it works normally. The chirp coefficient can be seen from the following description of determining the chirp coefficient.

[0125] 7、Optical link: used to simulate the information of optical fiber length, multiple connectors (such as the position information of multiple connectors, the reflectivity of multiple connectors, the insertion loss information) in optical communication link, received optical power, dispersion, wherein the insertion loss is used to evaluate the optical power loss caused by the intervention of optical devices or fiber segments in the optical communication link, and the dispersion is used to describe the dispersion phenomenon of different frequencies or wavelengths of light in the transmission process due to different transmission speeds or time delays.

[0126] 8. Photoelectric converter: It has a photodetector (PD) that is mainly used to convert optical signals into electrical signals. It also has an avalanche photodiode (APD) that can use the avalanche effect in a semiconductor to enhance the photoelectric conversion effect. It can be used to set the responsivity, thermal noise / shot noise, and dark current, where the responsivity is a physical quantity that describes the photoelectric conversion capability of a photoelectric converter (such as a photodiode), which reflects the efficiency of the photoelectric converter in converting optical signals into electrical signals. Thermal noise is caused by the thermal vibration of electrons in a conductor, and it exists in all electronic devices and transmission media. Thermal noise, also known as resistance noise or Johnson noise, is caused by the random thermal motion of electrons. Shot noise (also known as scatter noise) is caused by the fact that photo-generated current is a randomly generated current that fluctuates randomly in size. This fluctuation is caused by the random generation and recombination of photo-generated electrons and holes. Dark current refers to the current flowing in a photodetector (such as a solar cell, a photodiode, etc.) in the absence of light. It is mainly composed of leakage current formed by surface defects of the crystal material and intrinsic dark current formed by thermal diffusion of carriers.

[0127] 9. Trans-impedance amplifier (TIA): It is mainly used to convert the weak current signal generated by the photodetector (such as a photodiode) into a voltage signal. It can be used to set the trans-impedance value and the band-limiting effect.

[0128] 10. Analog-to-digital converter (ADC): It is mainly used to convert analog signals into digital signals. It can be used to set the quantization bit number, the sampling rate, and the band-limiting effect.

[0129] 11. Filter + resampling module: It can include an anti-aliasing filter that is used to remove or attenuate high-frequency information above the sampling frequency before the analog signal is sampled to prevent aliasing. It can also include a high-pass filter / low-pass filter / band-pass filter. This module can perform downsampling and signal synchronization.

[0130] 12、Rx oDSP: It includes a feed forward equalizer (FFE), which is an equalization technique used at the receiving end to compensate for channel loss. It can also calculate the bit error rate (BER) of the received signal, maximum likelihood sequence estimation (MLSE), signal-to-noise ratio (SNR), and spectrum, all of which can be used to evaluate the performance of an optical communication system. It can also be used to obtain the level distribution of the electrical signal, demodulation, and other calculations such as standard deviation / variance.

[0131] In the optical communication link simulation system, the key devices can include an oDSP chip, a laser, and an optical link. The oDSP chip can be used for signal processing such as level distribution calculation, the laser can be used to set the chirp coefficient, and the optical link can be used to set the multiple splice information present in the optical communication link.

[0132] Specifically, different intensity values of MPI noise are set in the optical communication link simulation system, and the level distribution corresponding to the intensity values of the MPI noise is obtained at the receiving end after simulation by the optical communication link simulation system. Since the MPI effect is caused by the superposition of signals from multiple reflection paths onto the signal of the main path, the intensity of the MPI noise is the intensity of the superimposed signal minus the intensity of the original signal, i.e., the term after the plus sign in formula (2). As can be seen from the formula, the intensity of the MPI noise can be determined according to the reflection point distance, the splice reflectivity, and the insertion loss information. The reflection point distance affects the time delay of the reflection path formed by the ith reflection point and the jth reflection point relative to the original signal.

[0133] Therefore, in order to set different intensities of MPI noise, the optical communication link simulation system sets different intensities of MPI noise by setting different position information, reflectivity information, and insertion loss information of multiple reflection points at each simulation.

[0134] In each simulation, the simulation system converts a 3*N matrix including the position information, reflectivity information and insertion loss information of the plurality of reflection points into a 5*N(N-1) / 2 matrix by setting different position information, reflectivity information and insertion loss information of the plurality of reflection points, in combination with inherent loss coefficients in the optical fiber and the propagation rate of the optical signal in the optical fiber. For the 3*N matrix, the 3 rows of the matrix are the reflection point position, reflectivity and insertion loss, and the N columns are the N reflection points. For the 5*N(N-1) / 2 matrix, the 5 rows are the distance information between the reflection points, the two reflection point joint serial number information, the secondary reflection coefficient under a single reflection path and the time delay information corresponding to being superimposed on the main signal, and each column represents a reflection signal carried on a reflection path. The reflection point in the above can be understood as a reflection joint in the optical communication link.

[0135] FIG. 5 is a schematic diagram of an optical communication link and MPI effect in the optical communication link. As shown in FIG. 5, the optical communication link is an actual optical fiber transmission link, which includes optical fibers, connectors and the like, and an optical signal can be transmitted by a transmitting device and received by a receiving device. The link includes six reflection points, such as reflection points 1-6 shown in the figure, and a new reflection path is formed between any two reflection points, that is, a new transmission path formed after the signal is reflected by two reflection points. For example, for reflection point 1 and reflection point 2, when the signal is transmitted to reflection point 2, the signal cannot directly pass through reflection point 1, but is reflected by reflection point 1, reaches reflection point 2, is reflected by reflection point 2, and finally passes through reflection point 1 for transmission. The new path formed after the signal is reflected is R 21 , that is, the signal passes through reflection point 1 and reflection point 2 twice to be transmitted through reflection point 1.

[0136] It can be understood that FIG. 5 shows all the reflection paths of the signals reflected by the six reflection points. R ij of each reflection path represents the multipath interference signal (hereinafter referred to as a reflection signal) between the i-th reflection point and the j-th reflection point. For example, R 21 represents the reflection signal between reflection point 1 and reflection point 2, and R 32 represents the reflection signal between reflection point 3 and reflection point 2. Therefore, as shown in FIG. 5, there are a total of 15 reflection signals. Each reflection signal can be regarded as each column of the 5*N(N-1) / 2 matrix, and the 5 rows of each column (i.e., the distance information between the reflection points, the two reflection point joint serial number information, the secondary reflection coefficient under a single reflection path and the time delay information corresponding to being superimposed on the main signal) represent the information of each reflection signal.

[0137] In addition, it can also be seen from FIG. 5 that there is a service signal which is transmitted directly to the receiving device through a direct path without any reflection, and the service signal can be an example of the main signal transmitted on the main path described in the present application. The reflected signals on the 15 reflected paths are superimposed on the service signal, and the 15 reflected signals are noise to the service signal, i.e., MPI noise. The receiving device receives the signal superimposed with the 15 reflected signals and analyzes the signal.

[0138] Finally, the simulation system superimposes the 5*N(N-1) / 2 matrix of each column of reflected signals on the corresponding main signal, obtains the level distribution through subsequent photoelectric conversion and signal processing, calculates and records the comparison value of the highest level distribution and the lowest level distribution at each simulation, and the intensity of the MPI noise at each simulation can be determined according to the position information, reflectivity information and insertion loss information of the multiple reflection points set at each simulation. Therefore, a corresponding relationship between the intensity of the MPI noise and the comparison value of the highest level distribution and the lowest level distribution can be obtained at each simulation, and a corresponding relationship between multiple intensities of MPI noise and multiple comparison values of the highest level distribution and the lowest level distribution can be obtained through multiple simulations. The corresponding relationship can be presented in the form of a corresponding relationship feature map (as shown in FIG. 6).

[0139] Hereinafter, the comparison value of the highest level distribution and the lowest level distribution is exemplarily described as the standard deviation difference value of the highest level distribution and the lowest level distribution / the standard deviation ratio of the highest level distribution and the lowest level distribution.

[0140] Fig. 6 is a schematic diagram of the difference / ratio of the standard deviations of the highest level distribution and the lowest level distribution under different intensities of MPI noise. As can be seen from Fig. 6, the intensity of MPI noise is determined according to the position information, reflectivity information and insertion loss information of the plurality of reflection points, so the intensity of MPI noise can be obtained by setting different position information, reflectivity information and insertion loss information of the plurality of reflection points in each simulation. Since the level distribution of the signal can be obtained in each simulation, the difference between the standard deviation of the highest level distribution and the standard deviation of the lowest level distribution is calculated and recorded to obtain the corresponding relationship between the difference of the standard deviations of the highest level distribution and the lowest level distribution and the intensity of MPI noise; or the ratio of the standard deviation of the highest level distribution and the standard deviation of the lowest level distribution is calculated and recorded to obtain the corresponding relationship between the ratio of the standard deviations of the highest level distribution and the lowest level distribution and the intensity of MPI noise. As shown in Fig. 6, the intensity of MPI noise ranges from -25 dB to -45 dB, Fig. 6(a) shows the corresponding relationship curve between the intensity of MPI noise and the difference of the standard deviations of the highest level distribution and the lowest level distribution obtained after multiple simulations, and Fig. 6(b) shows the corresponding relationship curve between the intensity of MPI noise and the ratio of the standard deviations of the highest level distribution and the lowest level distribution obtained after multiple simulations.

[0141] The calculated and recorded plurality of differences of the standard deviations of the highest level distribution and the lowest level distribution and the corresponding plurality of intensities of MPI noise, and the plurality of ratios of the standard deviations of the highest level distribution and the lowest level distribution and the corresponding plurality of intensities of MPI noise can also be stored in the characteristic parameter library. The characteristic parameter library is established on the basis of the simulation system of the optical communication link, and is constructed by the simulation system after forward derivation of the difference / ratio of the standard deviations of the highest level distribution and the lowest level distribution according to the set intensity of MPI noise, and then combined with multiple actual measurement training and correction.

[0142] Fig. 6 is an example of PAM-4 modulation signal, σ4 represents the standard deviation of the highest level distribution, σ1 represents the standard deviation of the lowest level distribution, the standard deviation of the highest level distribution reflects the dispersion degree of the signal amplitude value received at the highest level, and the standard deviation of the lowest level distribution reflects the dispersion degree of the signal amplitude value received at the lowest level. The data points in Fig. 6(a) are a plurality of differences of the standard deviations of the highest level distribution and the lowest level distribution obtained by measuring and calculating the first electrical signal multiple times in each simulation, and the data points in Fig. 6(b) are a plurality of ratios of the standard deviations of the highest level distribution and the lowest level distribution obtained by measuring and calculating the first electrical signal multiple times in each simulation, and the plurality of data points correspond to multiple measurements and calculations respectively. In each simulation, the data points in Fig. 6(a) / the plurality of data points in Fig. 6(b) are averaged to obtain the average value in Fig. 6(a) / Fig. 6(b).

[0143] It should be noted that the correspondence between the comparison value of the highest level distribution and the lowest level distribution and the intensity of the MPI noise can be stored in the form of a curve characteristic map (for example, FIG. 6), or can also be stored in the form of a table, for example, the comparison value of the highest level distribution and the lowest level distribution obtained each time the simulation is performed and the intensity of the corresponding MPI noise are recorded in a table for storage, or can also be stored in the form of a database (for example, a characteristic parameter library), and the like, which are not limited by the present application.

[0144] It should also be noted that the range of -25dB to -45dB of the intensity of the MPI noise described above is only an example of the intensity range of the MPI noise, and the intensity range of the MPI noise can also be other ranges, which are determined according to the actual optical communication link and are not limited. In addition, the intensity of the MPI noise in the example range of 25dB to -45dB reflects both normal and abnormal cases of the optical communication link, for example, when the intensity of the MPI noise is in the range of -25dB to -30dB, it can be judged that the optical communication link is abnormal, and when the intensity of the MPI noise is in the range of -30dB to -45dB, it can be judged that the optical communication link is normal, that is, according to the intensity of the MPI noise, it can be judged whether the optical communication link is abnormal (or whether there is damage) in order to subsequently determine whether the optical communication link needs to be repaired / optimized.

[0145] Step two, the receiving device detects the first electrical signal to obtain a first level distribution corresponding to the first electrical signal, the first level distribution including a highest level distribution and a lowest level distribution. According to the correspondence between the comparison value of the plurality of highest level distributions and lowest level distributions and the intensity of the plurality of MPI noises, the intensity of the MPI noise corresponding to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal is determined, and the comparison value of the plurality of highest level distributions and lowest level distributions includes the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal.

[0146] In one way, the receiving device measures the first electrical signal multiple times to obtain multiple first level distributions corresponding to the first electrical signal, i.e., multiple highest level distributions and multiple lowest level distributions, i.e., one-to-one correspondence between multiple measurements and multiple highest level distributions and multiple lowest level distributions. The standard deviation difference / ratio of the highest level distribution and the lowest level distribution corresponding to each measurement is calculated, and the standard deviation difference / ratio of multiple highest level distributions and multiple lowest level distributions is calculated through multiple measurements. The standard deviation difference / ratio of multiple highest level and lowest level is averaged to obtain the homogenized standard deviation difference / ratio. The homogenized standard deviation difference / ratio is compared with the standard deviation difference / ratio of the highest level distribution and the lowest level distribution stored in the feature parameter library in step one to determine the intensity of the MPI noise corresponding to the homogenized standard deviation difference / ratio. The homogenized standard deviation difference / ratio is an example of the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal.

[0147] In one way, the histogram statistical information of the pre-defined length data code stream is collected by the oDSP chip in the optical module, and the pre-defined length data code stream is a form of the first electrical signal. The amplitude value of each data point in the data code stream is assigned to different intervals, and each interval corresponds to an electrical level. When the first electrical signal is a PAM-4 signal, four levels correspond to four intervals, and the histogram statistical information includes multiple data points in the interval corresponding to the highest level and multiple data points in the interval corresponding to the lowest level. According to the histogram statistical information, the highest level distribution and the lowest level distribution of the first electrical signal can be obtained, and the standard deviation of the highest level distribution and the standard deviation of the lowest level distribution can be calculated. The difference / ratio of the standard deviation of the highest level distribution and the standard deviation of the lowest level distribution is calculated in the oDSP chip or the host computer, and is compared with the difference / ratio of the standard deviation of the highest level distribution and the standard deviation of the lowest level distribution stored in the feature parameter library through the register storage reporting mode or directly in the host computer, and the intensity of the corresponding MPI noise is returned.

[0148] In one way, the data code stream is sampled by the oDSP chip in the optical module, and the simulation and calculation mentioned above can be directly inherited in the microcontroller unit (MCU) chip in the optical module. For example, the feature parameter library in the above can also be trained by the MCU chip in the optical module, and the calculation of the standard deviation difference / ratio of the highest level distribution and the lowest level distribution, the average calculation of the standard deviation difference / ratio of multiple highest level distributions and multiple lowest level distributions, and the comparison of the standard deviation difference / ratio with the feature parameter library to obtain the intensity of the MPI noise corresponding to the standard deviation difference / ratio can also be realized by the MCU chip in the optical module.

[0149] In the above scheme, by comparing the maximum level distribution and the minimum level distribution of the first electrical signal with the characteristic parameter library, that is, according to the correspondence between the maximum level distribution and the minimum level distribution of the first electrical signal and the intensity of the MPI noise, the intensity of the MPI noise corresponding to the maximum level distribution and the minimum level distribution of the first electrical signal is obtained, and the intensity of the MPI noise is used to measure the influence of the MPI effect on the optical communication link. The intensity of the MPI noise can be obtained in real time to determine whether the optical communication link is damaged and whether subsequent link repair is needed, without interrupting the current service, and without the need for additional hardware devices for detection, which is low in cost.

[0150] It should be noted that the above shows a method of associating the maximum level distribution and the minimum level distribution of the first electrical signal with the intensity of the MPI noise. Since the intensity of the MPI noise is associated with the amplitude of the level, in addition to using the maximum level distribution and the minimum level distribution to represent the amplitude of the level, other levels of the first electrical signal can also be associated with the intensity of the MPI noise, such as associating any two levels or multiple levels in PAM-4 modulation with the intensity of the MPI noise, and the like, which is not limited in the present application.

[0151] In one way, the chirp coefficient is determined according to the frequency response curve characteristic of the first electrical signal, comprising: obtaining a second correspondence relationship, the second correspondence relationship comprising a plurality of frequency response curve characteristics and a plurality of chirp coefficients; determining the chirp coefficient corresponding to the frequency response curve characteristic of the first electrical signal according to the second correspondence relationship, the plurality of frequency response curve characteristics comprising the frequency response curve characteristic of the first electrical signal.

[0152] In one way, the second correspondence relationship is obtained by simulation of an optical communication link simulation system, which is used to simulate the chirp effect in the optical communication link.

[0153] The principle of determining the chirp coefficient using the frequency response curve characteristic of the electrical signal is given below.

[0154] The influence of the chirp effect on the first optical communication can be represented by the following formula (5):

[0155] Wherein, a is the linewidth enhancement factor (an example of the chirp coefficient), K is the adiabatic chirp parameter, P(t) is the output power of the laser, P bias is the output power when the bias current is turned on. The first term before the plus sign in the brackets is called transient chirp, and the second term after the plus sign is called adiabatic chirp. In a system based on a directly modulated laser, the frequency response under the influence of chirp can be represented by the following formula:

[0156] where γ = πD / λ 2 / c, the first term before the plus sign is the frequency response caused by the transient chirp, and the second term after the plus sign is the frequency response caused by the adiabatic chirp, f is the frequency, L is the transmission distance, I is the bias current, P is the laser output power, D is the fiber dispersion parameter, and c is the speed of light in vacuum.

[0157] It can be seen that the frequency responses caused by different chirp effects are different, and different frequency domain responses are determined according to different linewidth enhancement factors. Since the linewidth enhancement factor affects the transient chirp and the adiabatic chirp, the linewidth enhancement factor a can be used to quantify the influence of the chirp effect on the optical communication link, that is, the linewidth enhancement factor a can be used as a chirp coefficient. Chirp degradation can be defined as the degradation of the linewidth enhancement factor.

[0158] The construction of the optical communication link simulation system, and the detection and quantification of the chirp effect and the degree of chirp degradation in the optical communication link are described in detail below. It should be noted that quantifying the chirp effect in the optical communication link means using a quantity / value to measure the influence of the chirp effect on the optical communication link.

[0159] Step 1, construct a mirror network of the optical communication link through the above-mentioned optical communication link end-to-end simulation system, obtain the correspondence between the multiple frequency response curve features and the multiple chirp coefficients, and the optical communication link simulation system described in step one can also simulate the chirp effect in the optical communication link. The correspondence between the multiple frequency response curve features and the multiple chirp coefficients is an example of the second correspondence.

[0160] It should be noted that the second correspondence can be obtained by the simulation system of the receiving device itself, or it can be obtained by another device and sent to the receiving device, which is not limited in the present application.

[0161] Specifically, by setting multiple different chirp coefficients in the optical communication link simulation system, multiple sets of frequency response curve graphs are simulated, the curve features (referred to as "frequency response curve features") of the frequency response curve graph corresponding to each chirp coefficient are identified and recorded, the correspondence between the frequency response curve features and the chirp coefficients is obtained, and the frequency response curve features and the corresponding chirp coefficients are stored in a feature parameter library for subsequent detection.

[0162] In one way, the frequency response curve features include at least one of the following: the stationary point information of the frequency response curve, the slope information between the stationary points of the frequency response curve, the bending degree of the frequency response curve, and the position information of the concave and convex parts of the frequency response curve.

[0163] Exemplarily, the frequency response curve characteristic is a stationary point information of the frequency response curve, which requires that the frequency response curve contains at least one stationary point, and the stationary point is a point with a derivative of 0, i.e., the stationary point information of the frequency response curve corresponds to the chirp coefficient. Whether it is a possible stationary point can be determined by judging the frequency spectrum density values of the points within a certain range before and after the point, and the certain range is determined by the sampling accuracy.

[0164] It should be noted that the curve characteristics of the plurality of frequency response curves represented by the plurality of frequency response curve characteristics each correspond to an electrical signal, and are not the plurality of characteristic information included in the frequency response curve characteristics. For example, the frequency response curve characteristics of the first electrical signal can include the stationary point information of the frequency response curve and the slope information between the stationary points of the frequency response curve, and the frequency response curve characteristics of the first electrical signal correspond to the chirp coefficient, which means that the stationary point information of the frequency response curve and the slope information between the stationary points of the frequency response curve of the first electrical signal correspond to the chirp coefficient.

[0165] The following is an example of using a line width enhancement factor α as a chirp coefficient.

[0166] FIG. 7 is a frequency response curve under different line width enhancement factors α. As shown in (a) of FIG. 7, there are two frequency response curves, which are the frequency response curve of the signal in the sending end (Tx) and the frequency response curve of the signal in the receiving end (Rx) before the FFE. It can be seen that, when the line width enhancement factor α is 1, the frequency response curve of the signal received at Rx after the influence of the chirp effect in the optical communication link has changed. Similarly, (b) of FIG. 7 shows the frequency response curve of the received signal under the line width enhancement factor α of 2 for the same transmitted signal. As shown in FIG. 7, under different line width enhancement factors α, the same transmitted signal is affected differently by the chirp effect, and therefore the line width enhancement factor α can be used as a chirp coefficient to measure the influence of the chirp effect on the optical communication link.

[0167] In addition, in order to reflect the frequency response curves under different line width enhancement factors a, the frequency response curve corresponding to a can be represented by the saddle point information. For example, in (a) of FIG. 7, the saddle point information of the frequency response curve corresponding to a = 1 has a saddle point coordinate (x, y) = (15.918, -107.713), and a = 1 and the corresponding (x, y) = (15.918, -107.713) can be stored in the characteristic parameter library. For another example, in (b) of FIG. 7, the saddle point information of the frequency response curve corresponding to a = 2 has a saddle point coordinate (x, y) = (13.2812, -109.304) and (x, y) = (22.5586, -105.18), and a = 2 and the corresponding (x, y) = (13.2812, -109.304) and (x, y) = (22.5586, -105.18) can be stored in the characteristic parameter library, so that the corresponding line width enhancement factor a can be determined according to the saddle point coordinate subsequently.

[0168] It should be noted that the frequency response curve characteristics are not limited to the saddle point information, the slope information between the saddle points, the bending degree, and the position information of the concave and convex parts described above. Information used to reflect / describe / represent the frequency response curve can be referred to as frequency response curve characteristics, and there are many frequency response curve characteristics used to describe the frequency response curve. In addition to the information listed above, for example, the frequency response curve characteristics can include the gain of the frequency response curve and the bandwidth of the frequency response curve. In order to be brief, they will not be listed one by one here.

[0169] In step 2, a second optical signal is received, and the second optical signal is optoelectronically converted to obtain a second electrical signal. The first optical signal corresponds to a first time, and the second optical signal corresponds to a second time. The second time is after the first time. According to the frequency response curve characteristics of the second electrical signal and the frequency response curve characteristics of the first electrical signal, it is determined whether the chirp degradation exists in the optical communication link. The optical communication link is also used to transmit the second optical signal. The first optical signal and the second optical signal are the same optical signal sent by the sending device at different times.

[0170] The frequency response curve characteristics of the second electrical signal include at least one of the following: the curve characteristics of the frequency response curve of the second electrical signal itself, and the curve characteristics of the frequency response curve of the compensation performed by the equalizer on the second electrical signal.

[0171] It should be understood that when determining whether the optical communication link has chirp degradation according to the frequency response curve characteristic of the second electrical signal and the frequency response curve characteristic of the first electrical signal, the frequency response curve characteristic of the second electrical signal and the frequency response curve characteristic of the first electrical signal are curve characteristics of the same type of frequency response curve, that is, the frequency response curve characteristic of the second electrical signal and the frequency response curve characteristic of the first electrical signal are both curve characteristics of the frequency response curve of the first electrical signal and the second electrical signal themselves, or the frequency response curve characteristic of the second electrical signal and the frequency response curve characteristic of the first electrical signal are both curve characteristics of the frequency response curve of the first electrical signal and the second electrical signal compensated by the equalizer.

[0172] In one mode, according to a second correspondence relationship, a chirp coefficient corresponding to the frequency response curve characteristic of the second electrical signal is determined, and the plurality of frequency response curve characteristics include the frequency response curve characteristic of the second electrical signal; whether the optical communication link has chirp degradation is determined according to the chirp coefficient corresponding to the frequency response curve characteristic of the second electrical signal and the chirp coefficient corresponding to the frequency response curve characteristic of the first electrical signal.

[0173] The following is an example of illustrating the stationary point coordinates as frequency response curve characteristics.

[0174] For example, the sending device sends the first optical signal and the second optical signal at two time points respectively, and correspondingly, the receiving device receives the first optical signal and the second optical signal at two time points respectively, and the first optical signal and the second optical signal are the same optical signal sent by the sending device at different times. For the convenience of description, the first optical signal is sent at the first time, and the second optical signal is sent at the second time, and correspondingly, the receiving device receives the first optical signal at the first time and receives the second optical signal at the second time, and the first time is before the second time.

[0175] The receiving device can also perform photoelectric conversion on the first optical signal and the second optical signal respectively to obtain a first electrical signal corresponding to the first optical signal and a second electrical signal corresponding to the second optical signal; and detect the first electrical signal and the second electrical signal respectively to obtain a frequency response curve of the first electrical signal and a frequency response curve of the second electrical signal, and the detection can be online detection; and derive the frequency response curve of the first electrical signal and the frequency response curve of the second electrical signal respectively to obtain a stationary point coordinate corresponding to the first electrical signal and a stationary point coordinate corresponding to the second electrical signal, and determine whether the optical communication link has chirp degradation according to the stationary point coordinate corresponding to the first electrical signal and the stationary point coordinate corresponding to the second electrical signal.

[0176] Exemplarily, when the stationary point coordinate corresponding to the second electrical signal is closer to the center point than the stationary point coordinate corresponding to the first electrical signal, it can be determined that the optical communication link has chirp degradation. As shown in FIG. 7, the signal in Rx in (a) of FIG. 7 is regarded as the first electrical signal, and the stationary point coordinate corresponding to the first electrical signal is (x, y) = (15.918, -107.713); the signal in Rx in (b) of FIG. 7 is regarded as the second electrical signal, and the stationary point coordinate corresponding to the second electrical signal is (x, y) = (13.2812, -109.304). It can be seen that the stationary point coordinate corresponding to the second electrical signal is closer to the center than the stationary point coordinate corresponding to the first electrical signal, that is, it can be determined that the optical communication link has chirp degradation.

[0177] In one mode, the receiving device determines, according to the second correspondence relationship, a chirp coefficient corresponding to a frequency response curve feature of the second electrical signal, the plurality of frequency response curve features including the frequency response curve feature of the second electrical signal; and determines, according to the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal and the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal, whether the optical communication link has chirp degradation.

[0178] In one mode, when the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal is greater than the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal, the optical communication link has chirp degradation.

[0179] In one mode, the receiving device determines, according to the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal and the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal, a chirp degradation value, the chirp degradation value being used to measure the degree of chirp degradation.

[0180] Exemplarily, as shown in (a) of FIG. 7, when the stationary point coordinate of the first electrical signal is (x, y) = (15.918, -107.713) or the stationary point coordinate of the first electrical signal is within a certain range of the coordinate (x, y) = (15.918, -107.713), it can be determined that the line width enhancement factor corresponding to the stationary point coordinate of the first electrical signal is α = 1; for example, the stationary point coordinates of the second electrical signal are (x, y) = (13.2812, -109.304) and (x, y) = (22.5586, -105.18), the stationary point coordinate of the second electrical signal which is closer to the center is compared with the stationary point coordinate of the first electrical signal, that is, when the stationary point coordinate of the second electrical signal is (x, y) = (13.2812, -109.304) or the stationary point coordinate of the second electrical signal is within a certain range of the coordinate (x, y) = (13.2812, -109.304), it can be determined that the line width enhancement factor corresponding to the stationary point coordinate of the second electrical signal is α = 2. Since α = 2 is greater than α = 1, it can be determined that the optical communication link has chirp degradation.

[0181] In addition, the line width enhancement factor a = 2 and the line width enhancement factor a = 1 can be compared to obtain a comparison value of the line width enhancement factor, for example, the difference value 1 of a = 2 and a = 1 is used to measure the degree of chirp degradation. The difference value 1 of the line width enhancement factor is an example of the chirp degradation value.

[0182] It should be noted that the chirp degradation value can be the difference value of the chirp coefficient, the ratio value of the chirp coefficient, or other forms of comparison value of the chirp coefficient, which is not limited in the present application.

[0183] In one way, the receiving device uses an oDSP chip to collect a data stream of a predefined length, and uses the oDSP chip or an upper computer (for example, a server / computer) to perform Fourier transform on the data stream to obtain frequency domain response curve information corresponding to the data stream; and uses a register to report the frequency domain response curve information, for example, reporting through an inter-integrated circuit (IIC) interface or the like, or directly processing the frequency domain response curve information using the upper computer to obtain a frequency response curve feature, comparing the frequency response curve feature with a frequency response curve feature in a feature parameter library to obtain a chirp coefficient corresponding to the frequency response curve feature of the data stream, and comparing the chirp coefficients at different times to determine whether there is chirp degradation. The data stream of the predefined length is one form of the first electrical signal or the second electrical signal.

[0184] For example, the frequency response curve obtained by using the oDSP chip or the upper computer (for example, the server / computer) to perform Fourier transform on the data stream can be as shown in the curve corresponding to the signal in Rx before FFE in (b) of FIG. 7, therefore, the frequency response curve feature obtained by directly processing the frequency domain information using the upper computer can be the stationary point coordinates (x, y) = (13.2812, -109.304) and the stationary point coordinates (x, y) = (22.5586, -105.18), by comparing the stationary point coordinates stored in the feature parameter library, the chirp coefficient corresponding to the frequency response curve feature of the data stream of the predefined length, that is, the line width enhancement factor a = 2 corresponding to the stationary point coordinates, is obtained.

[0185] The frequency response curve feature of the first electrical signal or the second electrical signal obtained in this way is the curve feature of the frequency response curve of the first electrical signal or the second electrical signal itself (such as the frequency response curve shown in FIG. 7), and the first electrical signal or the second electrical signal is an original electrical signal (which can be understood as an electrical signal without any processing), therefore, the present application can obtain the curve feature of the frequency response curve of the original first electrical signal or second electrical signal itself and the corresponding relationship with the chirp coefficient.

[0186] In one mode, the receiving device uses an oDSP chip to collect a data stream of a predefined length, uses the adaptive equalization function of the oDSP chip to fill in the concave and convex parts of the curve in the frequency domain of the electrical signal, and uses the register to report the information of the frequency response curve of the equalizer, for example, through an inter-integrated circuit (IIC) interface or the like, or uses the host computer to directly process the information of the frequency response curve of the equalizer to obtain the frequency response curve feature, compares the frequency response curve feature with the frequency response curve features in the feature parameter library, obtains the chirp coefficient corresponding to the frequency response curve feature of the data stream, and compares the chirp coefficients at different times to determine whether there is chirp degradation. The equalizer can be adjusted by parameters such as tap coefficients to optimize the frequency response feature of the equalizer.

[0187] Exemplarily, the equalizer is a least mean square (LMS) equalizer, and FIG. 8 is a frequency response curve of the LMS equalizer under different chirp coefficients, which is a line width enhancement factor α. As shown in FIG. 8, the bending degree of the frequency response curve corresponding to different chirp coefficients is different, and the bending degree of the frequency response curve of the LMS equalizer corresponding to the chirp-degraded signal is more obvious, and the convex part is closer to the center position (i.e., the position corresponding to the normalized frequency of 0). For example, the frequency response curve corresponding to α = 3 is more obviously bent than the frequency response curve corresponding to α = 2, and the convex part is closer to the center position. For another example, the frequency response curve corresponding to α = 2 is more obviously bent than the frequency response curve corresponding to α = 1, and the convex part is closer to the center position. For another example, the frequency response curve corresponding to α = 1 is more obviously bent than the frequency response curve corresponding to α = 0, and the convex part is closer to the center position. If α = 0, α = 1, α = 2, and α = 3 respectively correspond to the frequency response curves of the LMS equalizer obtained by the receiving device through the optical communication link at different times, the plurality of electrical signals are obtained by photoelectric conversion from a plurality of optical signals, and the plurality of optical signals are the same optical signal transmitted by the transmitting device at different times, the chirp coefficients at different times can be compared to determine that there is chirp degradation in the optical communication link.

[0188] The frequency response curve characteristic of the first electrical signal or the second electrical signal obtained in this way is the curve characteristic of the frequency response curve of the equalizer compensating for the first electrical signal or the second electrical signal (the frequency response curve shown in FIG. 8), which is the original electrical signal (which can be understood as an electrical signal that has not been processed in any way). The frequency response curve of the equalizer compensating for the first electrical signal or the second electrical signal can be understood as the frequency response curve of the equalizer obtained by inputting the first electrical signal or the second electrical signal into the equalizer. Therefore, the application can also obtain the corresponding relationship between the curve characteristic of the frequency response curve of the equalizer compensating for the original first electrical signal or second electrical signal and the chirp coefficient.

[0189] In one way, the data stream is sampled by the oDSP chip in the optical module in a predefined length, and the above-mentioned data processing can be directly inherited in the microcontroller unit (MCU) chip in the optical module. The sampled and processed data is the frequency response curve of the electrical signal. For example, the feature parameter library in the above-mentioned can also be obtained by training the MCU chip in the optical module. The frequency response curve of the first electrical signal obtained by processing in the above-mentioned and the comparison of the curve characteristic of the frequency response curve with the feature parameter library to obtain the chirp coefficient corresponding to the frequency response curve characteristic can also be realized by the MCU chip in the optical module.

[0190] In the above-mentioned scheme, the chirp coefficient corresponding to the frequency response curve characteristic of the electrical signal is obtained by comparing the frequency response curve characteristic with the feature parameter library, that is, according to the corresponding relationship between the frequency response curve characteristic and the chirp coefficient. The chirp coefficient is used to measure the influence of the chirp effect on the optical communication link, and the frequency response curve characteristic at different times or the chirp coefficient corresponding to the frequency response curve characteristic can be compared to determine whether the optical communication link has chirp degradation. Not only can the change of the chirp in the optical communication link be obtained in real time without interrupting the current service, but also the detection does not need to rely on additional hardware devices, which is low in cost.

[0191] The above describes the method embodiment of the embodiment of the application, and the corresponding device embodiment is introduced below.

[0192] In order to realize the functions of the communication device (such as a receiving device, a sending device, etc.) in the embodiment of the application, each device can realize the corresponding function in the form of a hardware structure, a software module, or a hardware structure plus a software module.

[0193] FIG. 9 is a schematic block diagram of the optical communication link detection apparatus 1000 according to an embodiment of the present application. As shown in FIG. 9, the apparatus 1000 can include a transceiver unit 1010 and a processing unit 1020. The transceiver unit 1010 can be configured to communicate with an external device, and the processing unit 1020 can be configured to perform data processing. The transceiver unit 1010 can also be referred to as a communication interface or a transceiver unit. The processing unit 1020 can be configured to perform processing.

[0194] Optionally, the apparatus 1000 can further include a storage unit configured to store instructions and / or data. The processing unit 1020 can read the instructions and / or data stored in the storage unit to enable the apparatus to implement the foregoing method embodiments.

[0195] By way of example, the apparatus 1000 can be a receiving device, such as an AAU or a BBU, or an apparatus, such as a chip, a chip system or a circuit, which is applicable to or matched with a receiving device and can enable the receiving device to perform the method. For more details, refer to the description of the chip system shown in FIG. 11.

[0196] By way of example, the apparatus 1000 can be a transmitting device, such as an AAU or a BBU, or an apparatus, such as a chip, a chip system or a circuit, which is applicable to or matched with a transmitting device and can enable the transmitting device to perform the method. For more details, refer to the description of the chip system shown in FIG. 11.

[0197] In one possible design, the apparatus 1000 can implement the steps or procedures performed by a receiving device in the foregoing method embodiments, in which the processing unit 1020 is configured to perform processing-related operations of the receiving device in the foregoing method embodiments, and the transceiver unit 1010 is configured to perform transceiving-related operations of the first device in the foregoing method embodiments.

[0198] By way of example, the transceiver unit 1010 can be configured to receive the first optical signal, and the processing unit 1020 can be configured to determine information of an optical communication link according to a parameter of a first electrical signal, the optical communication link being used to transmit the first optical signal. The parameter of the first electrical signal includes at least one of a comparison value of a highest level distribution and a lowest level distribution of the first electrical signal, and a frequency response curve feature of the first electrical signal. The information of the optical communication link includes at least one of an intensity of multipath interference (MPI) noise and a chirp coefficient. The intensity of the MPI noise is used to measure the influence of the MPI effect on the optical communication link, and the chirp coefficient is used to measure the influence of the chirp effect on the optical communication link.

[0199] In another possible design, the apparatus 1000 can implement the steps performed by a sending device in the above method embodiments, where the transceiver unit 1010 is configured to perform the transceiving-related operations of the sending device in the above method embodiments, and the processing unit 1020 is configured to perform the processing-related operations of the sending device in the above method embodiments.

[0200] For example, the transceiver unit 1010 is configured to send the first optical signal.

[0201] It is understood that the apparatus 1000 is embodied in the form of functional units. The term “unit” herein can refer to an application specific integrated circuit (ASIC), an electronic circuit, a processor (e.g., a shared processor, a dedicated processor, or a group processor, etc.) and a memory for executing one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that support the described functions. In an optional design, those skilled in the art can understand that the apparatus 1000 can be specifically a sending device in the above embodiments, and can be configured to perform the procedures and / or steps corresponding to the sending device in the above method embodiments, or the apparatus 1000 can be specifically a receiving device in the above embodiments, and can be configured to perform the procedures and / or steps corresponding to the receiving device in the above method embodiments. To avoid repetition, details are not described herein.

[0202] The apparatus 1000 in each of the above designs has the function of implementing the corresponding steps performed by the sending device in the above method embodiments, or the apparatus 1000 in each of the above designs has the function of implementing the corresponding steps performed by the receiving device in the above method embodiments. The function can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions; for example, the transceiver unit can be replaced by a transceiver (e.g., the sending unit in the transceiver unit can be replaced by a transmitter, and the receiving unit in the transceiver unit can be replaced by a receiver), and other units such as the processing unit can be replaced by a processor, which performs the transceiving operations and related processing operations in each of the method embodiments, respectively.

[0203] In addition, the above transceiver unit can also be a transceiver circuit (e.g., which can include a receiving circuit and a sending circuit), and the processing unit can be a processing circuit. In the embodiments of the present application, the above optical communication link detection apparatus can be a receiving device or a sending device in the above embodiments, or can be a chip or a chip system, such as an MCU chip or a system on chip (SoC). The transceiver unit can be an input / output circuit or a communication interface. The processing unit is a processor or a microprocessor integrated on the chip or an integrated circuit. Herein, no limitation is made.

[0204] Fig. 10 is a schematic block diagram of the optical communication link detection apparatus 2000 according to an embodiment of the present application. As shown in Fig. 10, the apparatus 2000 includes a processor 2010 and a transceiver 2020. The processor 2010 and the transceiver 2020 communicate with each other through an internal connection path. The processor 2010 is configured to execute instructions to control the transceiver 2020 to transmit and / or receive signals.

[0205] Optionally, the apparatus 2000 can further include a memory 2030, which communicates with the processor 2010 and the transceiver 2020 through an internal connection path. The memory 2030 is configured to store instructions, and the processor 2010 can execute the instructions stored in the memory 2030.

[0206] For example, the apparatus 2000 can be a transmitting device, such as an AAU or a BBU, or a device, such as a chip, a chip system or a circuit, which is applied to or matched with the transmitting device and can implement the method executed by the transmitting device. For details, refer to the related description of the chip system shown in Fig. 11.

[0207] For example, the apparatus 2000 can be a receiving device, such as an AAU or a BBU, or a device, such as a chip, a chip system or a circuit, which is applied to or matched with the receiving device and can implement the method executed by the receiving device. For details, refer to the related description of the chip system shown in Fig. 11.

[0208] In a possible implementation, the apparatus 2000 is configured to implement the processes and steps corresponding to the transmitting device in the above method embodiments.

[0209] In another possible implementation, the apparatus 2000 is configured to implement the processes and steps corresponding to the receiving device in the above method embodiments.

[0210] Optionally, the memory 2030 can include a read-only memory and a random access memory, and provide instructions and data to the processor. A part of the memory can also include a non-volatile random access memory. For example, the memory can also store device type information. The processor 2010 can be configured to execute the instructions stored in the memory, and when the processor 2010 executes the instructions stored in the memory, the processor 2010 is configured to execute the steps and / or processes of the above method embodiments corresponding to the transmitting end or the receiving end.

[0211] In the implementation process, the steps of the above method can be completed by the integrated logic circuit of hardware in the processor or the instruction in the form of software. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as hardware processor execution completion, or executed by the combination of hardware and software modules in the processor. The software module can be located in the mature storage medium in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, register, etc. The storage medium is located in the memory, and the processor reads the information in the memory, and combines the hardware to complete the steps of the above method. To avoid repetition, it will not be described in detail here.

[0212] It should be noted that the processor in the embodiments of the present application can be an integrated circuit chip with signal processing capability. In the implementation process, the steps of the above method embodiments can be completed by the integrated logic circuit of hardware in the processor or the instruction in the form of software. The above processor can be a general processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or a part of circuit for processing function in the foregoing CPU, other general processor, DSP, ASIC, FGPA or other programmable logic device, or other chip. The processor in the embodiments of the present application can realize or execute the disclosed methods, steps and logic block diagrams in the embodiments of the present application. The general processor can be a microprocessor or the processor can also be any conventional processor. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as hardware decoding processor execution completion, or executed by the combination of hardware and software modules in the decoding processor. The software module can be located in the mature storage medium in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, register, etc. The storage medium is located in the memory, and the processor reads the information in the memory, and combines the hardware to complete the steps of the above method.

[0213] It is to be understood that the memory in the embodiments of the present application can be a volatile memory or a nonvolatile memory, or can include both volatile and nonvolatile memory. Among them, the nonvolatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically EPROM (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM) used as an external cache. By way of example, and not limitation, many forms of RAM can be used, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory of the system and method described herein is intended to include, but not be limited to, these and any other suitable types of memory.

[0214] In the embodiments of the present application, the method described above can be executed by the sending device or the receiving device, or can be executed by a chip, a chip system or a circuit of the sending device or the receiving device, which can be installed in the sending device or the receiving device. In the following, the chip system of the sending device or the receiving device will be taken as an example for description.

[0215] FIG. 11 is a schematic block diagram of a chip system 3000 according to an embodiment of the present application. As shown in FIG. 11, the chip system 3000 (or also referred to as a processing system) includes a logic circuit 3010 and an input / output interface 3020.

[0216] The logic circuit 3010 can be a processing circuit in the chip system 3000. The logic circuit 3010 can be coupled to a storage unit, invoke instructions in the storage unit, so that the chip system 3000 can implement the methods and functions of the embodiments of the present application. The input / output interface 3020 can be an input / output circuit in the chip system 3000, output the processed information of the chip system 3000, or input the data or signaling information to be processed into the chip system 3000 for processing.

[0217] As an option, the chip system 3000 is configured to implement the operations performed by the sending device or the receiving device in the above method embodiments.

[0218] For example, the logic circuit 3010 is configured to implement the processing-related operations performed by the sending device in the above method embodiments, such as the processing-related operations performed by the sending device in the above embodiments; and the input / output interface 3020 is configured to implement the sending and / or receiving-related operations performed by the sending device in the above method embodiments, such as the sending and / or receiving-related operations performed by the sending device in the above embodiments.

[0219] For another example, the logic circuit 3010 is configured to implement the processing-related operations performed by the receiving device in the above method embodiments, such as the processing-related operations performed by the receiving device in the above embodiments; and the input / output interface 3020 is configured to implement the sending and / or receiving-related operations performed by the receiving device in the above method embodiments, such as the sending and / or receiving-related operations performed by the receiving device in the above embodiments.

[0220] The embodiments of the present application also provide a computer readable storage medium, which stores computer instructions for implementing the method performed by the sending device or the receiving device in the above method embodiments.

[0221] The embodiments of the present application also provide a computer program product, which contains instructions executed by a computer to implement the method performed by the sending device or the receiving device in the above method embodiments.

[0222] The embodiments of the present application also provide a communication system, which includes the sending device or the receiving device in the above embodiments.

[0223] The explanations and beneficial effects of the related contents in any of the above provided apparatuses can refer to the corresponding method embodiments provided above, which will not be repeated here.

[0224] In the present application, the methods and / or terms between the method embodiments can be mutually referenced without logical contradiction, for example, the functions and / or terms between the apparatus embodiments can be mutually referenced, for example, the functions and / or terms between the apparatus examples and the method examples can be mutually referenced.

[0225] In various embodiments of the present application, the size of the sequence number of the above processes does not mean the order of execution, the execution order of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0226] Those skilled in the art can appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0227] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0228] 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 above-described device embodiments 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 shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0229] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0230] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit.

[0231] If the functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or parts 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 methods described in the various embodiments of the present application. The aforementioned 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 media that can store program codes.

[0232] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of optical communication link detection, the method comprising: The method comprises: receiving a first optical signal and photoelectrically converting the first optical signal to obtain a first electrical signal; determining information of an optical communication link according to a parameter of the first electrical signal, the optical communication link being used for transmitting the first optical signal; the parameter of the first electrical signal comprises at least one of: a comparison value of a highest level distribution and a lowest level distribution of the first electrical signal, and a frequency response curve feature of the first electrical signal; the information of the optical communication link comprises at least one of: an intensity of multipath interference (MPI) noise, and a chirp coefficient; wherein the intensity of the MPI noise is used to measure the influence of MPI effect on the optical communication link, and the chirp coefficient is used to measure the influence of chirp effect on the optical communication link.

2. The method of claim 1, wherein, The method further comprises: determining the information of the optical communication link according to the parameter of the first electrical signal comprises: determining the intensity of the MPI noise according to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal; and / or 3. The method of claim 2, wherein, determining the chirp coefficient according to the frequency response curve feature of the first electrical signal. The method further comprises: determining the intensity of the MPI noise according to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal comprises:

4. The method according to any one of claims 1 to 3, characterized in that, obtaining a first correspondence relationship, the first correspondence relationship comprising a correspondence relationship between a plurality of comparison values of highest level distribution and lowest level distribution and a plurality of intensities of MPI noise; determining, according to the first correspondence relationship, the intensity of the multipath interference (MPI) noise corresponding to the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal, the plurality of comparison values of highest level distribution and lowest level distribution comprising the comparison value of the highest level distribution and the lowest level distribution of the first electrical signal.

5. The method of claim 2, wherein, The comparison value of the highest level distribution and the lowest level distribution comprises at least one of: a standard deviation difference value of the highest level distribution and the lowest level distribution, a standard deviation ratio value of the highest level distribution and the lowest level distribution, a variance difference value of the highest level distribution and the lowest level distribution, and a variance ratio value of the highest level distribution and the lowest level distribution. The method further comprises:

6. The method of claim 5, wherein, determining the chirp coefficient according to the frequency response curve feature of the first electrical signal comprises: obtaining a second correspondence relationship, the second correspondence relationship comprising a correspondence relationship between a plurality of frequency response curve features and a plurality of chirp coefficients; determining, according to the second correspondence relationship, the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal, the plurality of frequency response curve features comprising the frequency response curve feature of the first electrical signal.

7. The method of claim 6, wherein, The method further comprises: receiving a second optical signal and photoelectrically converting the second optical signal to obtain a second electrical signal, the first optical signal corresponding to a first time, and the second optical signal corresponding to a second time, the second time being after the first time; determining whether the optical communication link has chirp degradation according to the frequency response curve feature of the second electrical signal and the frequency response curve feature of the first electrical signal, the optical communication link also being used for transmitting the second optical signal. The method further comprises: According to the second correspondence relationship, determine the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal, the plurality of frequency response curve features including the frequency response curve feature of the second electrical signal; According to the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal and the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal, determine whether the optical communication link has chirp degradation.

8. The method of claim 7, wherein, When the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal is greater than the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal, the optical communication link has chirp degradation.

9. The method according to claim 7 or 8, characterized in that, The method further comprises: According to the chirp coefficient corresponding to the frequency response curve feature of the second electrical signal and the chirp coefficient corresponding to the frequency response curve feature of the first electrical signal, determine a chirp degradation value, the chirp degradation value being used to measure the degree of the chirp degradation.

10. The method according to any one of claims 5-9, characterized in that, The frequency response curve feature includes at least one of: The inflection point information of the frequency response curve, the slope information between the inflection points of the frequency response curve, the bending degree of the frequency response curve, and the concave-convex position information of the frequency response curve.

11. An apparatus, comprising: The apparatus comprises units or modules for performing the method of any one of claims 1 to 10.

12. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program or instructions, when the computer program or instructions are run on a computer, the method as claimed in any one of claims 1 to 10 is executed.

13. A chip, characterized by Comprise: The processor is used to call and run the computer program from the memory, so that the method as claimed in any one of claims 1 to 10 is executed.

14. A computer program product, characterised in that, When the computer program product is run on the computer, the method as claimed in any one of claims 1 to 10 is executed.

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