WO2022068702A1 - Signal processing method, apparatus, and system - Google Patents

Abstract

The present application relates to the field of optical communications, and discloses a signal processing method, apparatus, and system. The method comprises: obtaining a first relationship between a linear signal-to-noise ratio/non-linear signal-to-noise ratio in an optical transmission link and a relationship parameter, the relationship parameter being used for reflecting the relationship between the correlation of an upper sideband and a lower sideband of and frequency offset of a signal in the optical transmission link; obtaining a second relationship between the linear signal-to-noise ratio/non-linear signal-to-noise ratio in the optical transmission link and a signal-to-noise ratio; obtaining a target relationship parameter of a target signal received by means of the optical transmission link; obtaining a target signal-to-noise ratio of the target signal; and determining a linear signal-to-noise ratio corresponding to the target signal and a non-linear signal-to-noise ratio corresponding to the target signal on the basis of the target relationship parameter, the target signal-to-noise ratio, the first relationship, and the second relationship. According to the present application, linear signal-to-noise ratios and non-linear signal-to-noise ratios corresponding to signals can be effectively distinguished. The present application is used for measurement of linear signal-to-noise ratios and non-linear signal-to-noise ratios.

Description

Signal processing method, device and system

This application claims the priority of the Chinese patent application with the application number 202011057697.8 and the application name "Signal Processing Method, Device and System" filed on September 29, 2020, the entire contents of which are incorporated into this application by reference.

technical field

The present application relates to the field of optical communication, and in particular, to a signal processing method, device and system.

Background technique

In the optical transmission system, the operator can detect the optical signal-to-noise ratio (OSNR) in the optical transmission link according to the optical signal-to-noise ratio monitoring equipment to evaluate the transmission quality (Quality) of the optical transmission link. of Transmission, QoT). However, the optical signal-to-noise ratio actually includes the linear signal-to-noise ratio caused by the optical amplifier and the like and the nonlinear signal-to-noise ratio caused by the optical transmission link itself and the like. At present, there is an urgent need for a signal processing method that can effectively distinguish the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal.

SUMMARY OF THE INVENTION

Embodiments of the present application provide a signal processing method, device, and system. The technical solution is as follows:

In a first aspect, a signal processing method is provided, the method comprising:

Obtain the first relationship of linear SNR, nonlinear SNR and relational parameters in the optical transmission link, the relational parameters are used to reflect the correlation and frequency offset of the upper sideband and lower sideband of the signal in the optical transmission link obtain the second relationship between the linear SNR, the nonlinear SNR and the SNR in the optical transmission link; obtain the target relationship parameters of the target signal received through the optical transmission link; obtain the target signal’s target SNR; based on the target relationship parameter, the target SNR, the first relationship and the second relationship, determine the linear SNR corresponding to the target signal and the nonlinear SNR corresponding to the target signal.

The present application establishes the first relationship between the linear SNR, the nonlinear SNR and the drop rate in the optical transmission link, and the first relationship between the linear SNR, the nonlinear SNR and the SNR in the optical transmission link Two relations, and based on the two relations, using the actually obtained target relation parameters and target SNR, determine the linear SNR and nonlinear SNR of the target signal, so as to realize the linear SNR and nonlinear SNR of the signal. Effective differentiation of noise ratio.

In an optional implementation manner, the first relationship is represented by the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio as independent variables, the dependent variable is the first relationship of the relationship parameters, and the second relationship is represented by the independent variable is the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio, and the dependent variable is the second relational expression of the signal-to-noise ratio, which is based on the target relational parameters, the target signal-to-noise ratio, the first relation and the second relation , the process of determining the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal includes: substituting the target relationship parameter into the first relationship, and substituting the target SNR into the second relationship formula, the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal are obtained by solving the binary quadratic equation system.

In the embodiment of the present application, the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal are obtained by solving the equation, the obtaining method is simple and fast, and the operation efficiency is high.

In the optical transmission link, chromatic dispersion will cause a certain time delay to signals of different frequencies, and the upper and lower sidebands of the target signal correspond to different frequencies. During the transmission process, the upper and lower sidebands will generate time domain This will affect the accuracy of the correlation of the upper and lower sidebands of the determined target signal, thereby affecting the detection accuracy of the target relationship parameters. Therefore, after receiving the digital signal, the signal processing apparatus performs chromatic dispersion compensation on the received digital signal to obtain a digital signal after chromatic dispersion compensation. After that, the signal processing device detects the relationship parameter of the digital signal after chromatic dispersion compensation, and obtains the target relationship parameter. In this way, the time calibration of the digital signal is realized, so that the accuracy of the acquired target relationship parameter can be improved. Among them, the chromatic dispersion compensation can be realized by correcting the phase of the received signal by using a time-domain digital filter or a frequency-domain digital equalizer.

In an optional implementation manner, the process of acquiring the first relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the relationship parameter in the optical transmission link includes: determining at least three types of the optical transmission link The linear SNR and the nonlinear SNR corresponding to each signal in the signal, to obtain at least three pairs of linear SNR and nonlinear SNR, the linear SNR and nonlinear SNR corresponding to the at least three signals obtain the relationship parameters of each of the at least three signals; and obtain the first relationship by fitting based on the at least three pairs of linear signal-to-noise ratio and nonlinear signal-to-noise ratio and the obtained relationship parameters. Exemplarily, the at least three signals are different in at least one of the following parameters: transmit power, magnification of the corresponding optical amplifier, type of the corresponding optical amplifier, or actively loaded noise.

Both linear noise and nonlinear noise will destroy the correlation between the upper and lower sidebands of the signal spectrum. However, linear noise is spectrally flat, while nonlinear noise is not spectrally flat. Therefore, when there is a frequency offset, the influence of linear noise and nonlinear noise on the correlation of the upper and lower sidebands of the spectrum is also different. , so a binary linear equation can be established to reflect the first relationship between the correlation between the linear SNR and the nonlinear SNR and the frequency. Exemplarily, the first relationship may be represented by the following first relationship:

Among them, A represents the relationship parameter, SNR _linear represents the linear SNR, SNR _nonlinear represents the nonlinear SNR, B ₁ represents the contribution of the linear noise to the relationship parameter A, and B ₂ represents the contribution of the nonlinear noise to the relationship parameter A. , _B3 represents the bias introduced by other inherent factors. By way of example, the inherent factors include transmitter-introduced noise, receiver-introduced noise, and/or the resolution of the receiver (eg, a coherent receiver).

In a first optional manner, the process of acquiring the relationship parameters of each of the at least three kinds of signals may include: respectively loading at least two different frequency offsets on the first signal in the digital domain to obtain at least two kinds of sub-signals, The first signal is any one of the at least three kinds of signals, and the relationship parameter of the first signal is used to reflect the relationship between the correlation between the upper sideband and the lower sideband of the first signal and the frequency offset. Determine the correlation between the upper sideband and the lower sideband of each sub-signal in the at least two sub-signals; based on the at least two frequency offsets, and the correlation between the upper sideband and the lower sideband of each sub-signal in the at least two sub-signals, fit to obtain The relationship parameter of the first signal.

In a second optional manner, the process of acquiring the relationship parameter of each of the at least three kinds of signals may include: receiving at least two kinds of sub-signals, where the at least two kinds of sub-signals are loaded with different at least two kinds of frequencies on the first signal. The signal obtained by the offset is, for example, a signal obtained by the coherent receiver by applying at least two different frequency offsets to the first signal. The first signal is any one of the at least three kinds of signals, and the relationship parameter of the first signal is used to reflect the relationship between the correlation between the upper sideband and the lower sideband of the first signal and the frequency offset. Determine the correlation between the upper sideband and the lower sideband of each sub-signal in the at least two sub-signals; based on the at least two frequency offsets, and the correlation between the upper sideband and the lower sideband of each sub-signal in the at least two sub-signals, fit to obtain The relationship parameter of the first signal.

In this embodiment of the present application, the upper sideband component (that is, part of the upper sideband) and the lower sideband component (that is, part of the lower sideband) of each sub-signal can be obtained by filtering, and then the correlation between the upper sideband component and the lower sideband component can be obtained. , to determine the correlation between the upper sideband and the lower sideband. In this way, the overall correlation of the upper sideband and the lower sideband can be reflected by the correlation of the parts of the upper sideband and the lower sideband, thereby reducing the computational complexity of the correlation.

Exemplarily, the process of determining the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals includes:

For each of the at least two sub-signals, obtain an upper sideband component obtained by filtering the upper sideband component of the sub-signal, obtain a lower sideband component obtained by filtering the lower sideband component of the sub-signal, and obtain the upper sideband component and the lower sideband component. The correlation of the lower sideband component is taken as the correlation between the upper sideband and the lower sideband of the sub-signal; wherein, the filtering positions of the upper sideband components of the at least two sub-signals are the same, and the filtering bandwidth is the same; the lower sideband of the at least two sub-signals The filtering positions of the component filtering are the same, and the filtering bandwidth is the same; the filtering bandwidth of the upper sideband component filtering of the same sub-signal is the same as the filtering bandwidth of the lower sideband component filtering. Correlation, it is no longer necessary to align the upper sideband component and the lower sideband component in the bandwidth, thereby reducing the computational complexity of the correlation.

In an optional implementation manner, the process of obtaining the second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link includes:

Determine the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to each of the at least three signals in the optical transmission link, and obtain at least three pairs of linear signal-to-noise ratio and nonlinear signal-to-noise ratio. The linear SNR and the nonlinear SNR are different; the SNR of each of the at least three signals is obtained; based on the at least three pairs of the linear SNR and the nonlinear SNR, and the obtained SNR The second relationship is obtained by fitting. Exemplarily, the at least three signals are different in at least one of the following parameters: transmit power, magnification of the corresponding optical amplifier, type of the corresponding optical amplifier, or actively loaded noise.

Because both linear noise and nonlinear noise will have an impact on the overall signal-to-noise ratio (for example, the SNR monitoring method based on the correlation of the upper and lower sidebands of the signal spectrum to determine the signal-to-noise ratio) when there is no frequency offset, but the upper and lower sideband signals The nonlinear noise is not as uncorrelated as Gaussian noise, nor has the same strong correlation as the signal itself, so the nonlinear noise does not have no contribution to the overall signal-to-noise ratio, but the contribution is not as linear as Just as loud. Therefore, a quadratic linear equation can be established to reflect the second relationship between the linear SNR and the nonlinear SNR and SNR. Exemplarily, the second relationship may be represented by the following second relationship:

Among them, SNR _meas represents signal-to-noise ratio, SNR _linear represents linear signal-to-noise ratio, SNR _nonlinear represents nonlinear signal-to-noise ratio, C ₁ represents the contribution of linear noise to SNR _meas , and C ₂ represents nonlinear noise to nonlinear The contribution of the SNR _nonlinear to the signal-to-noise ratio, C ₃ represents the bias introduced by other inherent factors.

Before fitting, at least three pairs of linear SNR and nonlinear SNR, and the acquired SNR are known; C ₁ , C ₂ and C ₃ are unknowns. By substituting at least three pairs of linear signal-to-noise ratio and nonlinear signal-to-noise ratio, and the obtained signal-to-noise ratio into the second relationship, C ₁ , C ₂ and C ₃ can be obtained by fitting. Substituting the fitted C ₁ , C ₂ and C ₃ into the second relational expression, the second relational expression with known coefficients can be obtained.

In an optional implementation manner, the relationship parameter is a drop rate, and the drop rate is a drop rate of the correlation between the upper sideband and the lower sideband of the signal in the optical transmission link as the frequency offset increases.

The relationship between the correlation and the frequency offset can be represented by a cubic function. The cubic function can more accurately reflect the relationship between the correlation and the frequency offset. Using the cubic function to describe the relationship between the correlation and the frequency offset can effectively improve the accuracy of the final fitting result. Exemplarily, the cubic function is a first formula, and the first formula is: y=Ax ³ +Z, where A represents the decline rate, y represents the correlation, x represents the frequency offset, and Z represents the offset introduced by other inherent factors , which is not zero.

In a second aspect, a signal processing apparatus is provided, the apparatus includes at least one module, and the at least one module can be used to implement the signal processing method provided by the first aspect or various possible implementations of the first aspect.

A third aspect provides a signal processing system, the signal processing system comprising: a coherent receiver and the signal processing apparatus according to any one of the foregoing second aspects; the coherent receiver is configured to receive an optical signal from an optical transmission link, and The received optical signal is converted into a digital signal, and the converted digital signal is sent to the signal processing device.

In an optional implementation, the coherent receiver includes:

The local oscillator laser is used to generate coherent light; the polarization beam splitter is used to divide the optical signal transmitted by the optical transmission link into mutually perpendicular first polarized light and second polarized light, and divide the coherent light into mutually perpendicular the third polarized light and the fourth polarized light;

Two 90° mixers, where one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light ; photodetector, for converting the optical signal output by the two 90° mixers into analog current; filter, for filtering the analog current to obtain the electrical signal corresponding to the target signal; analog-to-digital converter, It is used to convert the electrical signal corresponding to the target signal into a digital signal. The photodetector may be a balanced photodetector, and the balanced photodetector can realize noise cancellation and reduce noise in the output analog current.

Correspondingly, the signal processing device includes: a first digital band-pass filter for filtering the upper sideband component of the received signal; and a second digital band-pass filter for filtering the lower sideband component of the received signal.

In another optional implementation manner, the system further includes: an optical splitter, the number of the coherent receivers is 2, the optical splitter is used for receiving optical signals from the optical transmission link, and dividing the received optical signals into two paths The optical signals are respectively input to two coherent receivers, one of the two coherent receivers is used to filter the upper sideband component, and the other coherent receiver is used to filter the lower sideband component.

Optionally, each of the aforementioned coherent receivers includes:

The local oscillator laser is used to generate coherent light; the polarization beam splitter is used to divide the optical signal transmitted by the optical transmission link into mutually perpendicular first polarized light and second polarized light, and divide the coherent light into mutually perpendicular the third polarized light and the fourth polarized light;

Two 90° mixers, one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light; light The detector is used to convert the optical signals output by the two 90° mixers into analog currents; the low-pass filter is used to filter the analog currents to obtain electrical signals corresponding to the sideband components; the analog-to-digital converter, It is used to convert the electrical signal of the corresponding sideband component into a digital signal.

In an optional example, the aforementioned coherent receiver is also used to load a frequency offset for the received optical signal. Exemplarily, at least two different frequency offsets are applied to the received signal to obtain at least two sub-signals.

Optionally, when the signal processing system includes two coherent receivers, the two coherent receivers are used to load the received optical signal with a frequency offset. For example, if the center frequency of the optical signal is T, the baud rate of the optical signal is E, and the frequency offset to be loaded is L, then the center frequency of the local oscillator laser of a coherent receiver corresponding to the upper sideband of the signal is adjusted to be T+ L+E/2, so the position of the signal spectrum of the electrical signal corresponding to the upper sideband of the optical signal will move L in the positive direction relative to the origin; adjust the center frequency of the local oscillator laser of another coherent receiver corresponding to the lower sideband of the signal is T+L-E/2, so the position of the signal spectrum of the electrical signal corresponding to the lower sideband of the optical signal will move L in the positive direction relative to the origin. When the two coherent receivers are also used to filter the upper sideband component and the lower sideband component respectively, the positions of the signal spectrums of the electrical signals corresponding to the upper sideband component and the lower sideband component obtained by the final filtering are moved forward relative to the origin by L .

Exemplarily, the system further includes: a power measuring device, the power measuring device is configured to receive the optical signal from the optical transmission link, and measure the power of the target signal in the optical signal.

The aforementioned local oscillator lasers have various center frequencies that are tunable.

In a fourth aspect, the present application provides a computer device including a processor and a memory. The memory stores computer instructions; the processor executes the computer instructions stored in the memory, so that the computer device executes the first aspect or the methods provided by various possible implementations of the first aspect, so that the computer device deploys the second aspect or the first aspect. Various possible implementations of the second aspect provide the signal processing apparatus.

In a fifth aspect, the present application provides a computer-readable storage medium, where computer instructions are stored in the computer-readable storage medium, and the computer instructions instruct the computer device to execute the above-mentioned first aspect or various possible implementations of the first aspect. The method, or the computer instructions instruct the computer device to deploy the second aspect or the signal processing apparatus provided by various possible implementations of the second aspect.

In a sixth aspect, the present application provides a computer program product comprising computer instructions stored in a computer-readable storage medium. The processor of the computer device can read the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the first aspect or the method provided by various possible implementations of the first aspect, so that the computer The device deploys the second aspect or the signal processing apparatus provided by various possible implementations of the second aspect.

In a seventh aspect, a chip is provided. The chip may include programmable logic circuits and/or program instructions for implementing the signal processing method according to any one of the first aspects when the chip is running.

In an eighth aspect, an optical transmission system is provided, the optical transmission system comprising the signal processing system of any one of the foregoing third aspects. Exemplarily, the optical transmission system further includes one or more optical devices, such as WSS and/or optical amplifiers.

The beneficial effects brought by the technical solutions provided in the embodiments of the present application are:

The present application establishes the first relationship between the linear SNR, the nonlinear SNR and the drop rate in the optical transmission link, and the first relationship between the linear SNR, the nonlinear SNR and the SNR in the optical transmission link Two relations, and based on the two relations, using the actually obtained target relation parameters and target SNR, determine the linear SNR and nonlinear SNR of the target signal, so as to realize the linear SNR and nonlinear SNR of the signal. Effective differentiation of noise ratio.

In addition, the embodiment of the present application can simultaneously acquire the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal, and the acquisition efficiency of the signal-to-noise ratio is high, which is convenient for the staff to conduct a comprehensive and effective analysis of the transmission quality of the optical transmission link.

Further, the signal processing method provided by the embodiment of the present application does not limit the modulation format supported by the DSP, and can support the monitoring of the linear SNR and the nonlinear SNR of signals of different modulation formats, thereby improving the monitoring flexibility. .

Description of drawings

FIG. 1 is a schematic diagram of an application environment of an optical transmission system involved in a signal processing method provided by an embodiment of the present application;

FIG. 2 is a schematic diagram of an application environment of an optical transmission system involved in another signal processing method provided by an embodiment of the present application;

3 is a schematic flowchart of a signal processing method provided by an embodiment of the present application;

4 is a schematic diagram of the relationship between the wavelength and optical power of a signal provided by an embodiment of the present application;

5 is a schematic diagram of a frequency offset loading principle of an optical transmission system involved in a signal processing method provided by an embodiment of the present application;

6 is a schematic diagram of a frequency offset loading principle of an optical transmission system involved in another signal processing method provided by an embodiment of the present application;

7 is a schematic diagram of a filtering principle of an optical transmission system involved in a signal processing method provided by an embodiment of the present application;

8 is a schematic diagram of a filtering principle of an optical transmission system involved in another signal processing method provided by an embodiment of the present application;

Fig. 9 is the filtering principle schematic diagram of the optical transmission system involved in the signal processing method on the basis of Fig. 8 provided by the embodiment of the present application;

10 is a schematic diagram of a fitting result of a drop rate of a first signal provided by an embodiment of the present application;

FIG. 11 is a schematic diagram of the principle of calculating the signal-to-noise ratio of a signal by using an out-of-band interpolation method provided by an embodiment of the present application;

12 is a schematic diagram of the principle of calculating the signal-to-noise ratio of a signal using an error vector magnitude calculation method provided by an embodiment of the present application;

13 is a schematic structural diagram of a signal processing apparatus provided by an embodiment of the present application;

14 is a schematic structural diagram of a first relationship acquisition module provided by an embodiment of the present application;

FIG. 15 is a possible basic hardware architecture of the computer device provided by the embodiment of the present application;

16 is a schematic structural diagram of a signal processing system provided by an embodiment of the present application;

17 is a schematic structural diagram of another signal processing system provided by an embodiment of the present application;

18 is a schematic structural diagram of another signal processing system provided by an embodiment of the present application;

19 is a schematic structural diagram of still another signal processing system provided by an embodiment of the present application;

FIG. 20 is a schematic structural diagram of a signal processing system provided by another embodiment of the present application;

21 is a schematic structural diagram of another signal processing system provided by another embodiment of the present application;

FIG. 22 is a schematic structural diagram of still another signal processing system provided by another embodiment of the present application.

Detailed ways

In order to make the principles and technical solutions of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

Optical fiber (also known as line optical fiber) communication is a communication method in which optical signals are used as information carriers and optical fibers are used as transmission media. 1 and 2 are schematic diagrams of application environments of an optical transmission system (also referred to as an optical fiber communication system or an optical transmission network) involved in the signal processing method provided by the embodiments of the present application. The optical transmission system is based on optical fiber communication, which includes one or more optical devices. FIG. 1 assumes that the optical transmission system includes one wavelength selective switch (Wavelength Selective Switching, WSS) 101 and one optical amplifier 102 ; FIG. 2 assumes that the optical transmission system includes two WSS 101 and two optical amplifiers 102 . For example, the optical amplifier 102 is an Erbium Doped Fiber Amplifier (EDFA) or a Raman amplifier.

The embodiments of the present application do not limit the number and types of optical devices included in the optical transmission system. The optical transmission systems in FIG. 1 and FIG. 2 can use wavelength division multiplexing (Wavelength Division Multiplexing, WDM) technology to transmit service information through optical signals.

In the aforementioned optical transmission system, by monitoring the optical signal-to-noise ratio (SNR for short) of the optical transmission link (such as an optical fiber), the transmission quality of the optical signal can be evaluated. Signal-to-noise ratio refers to the ratio of signal power to noise power. However, the current signal processing method can only monitor the overall signal-to-noise ratio of the optical transmission link, and cannot distinguish the nonlinear signal-to-noise ratio from the linear signal-to-noise ratio, so the transmission quality of the optical transmission link cannot be accurately evaluated. Further, when a problem occurs in the optical transmission system, the source of the problem cannot be accurately located based on the acquired signal-to-noise ratio.

The embodiment of the present application provides a signal processing method, which can effectively distinguish a linear signal-to-noise ratio and a nonlinear signal-to-noise ratio of an optical transmission link. The signal processing method can be applied to a signal processing device, and the signal processing device can be arranged on the optical transmission link of the aforementioned optical transmission system. FIG. 3 is a schematic flowchart of a signal processing method provided by an embodiment of the present application. In practical applications, the signal to be processed by the signal processing device may have one or more channels. A signal of one channel is taken as an example for description, and the processing process of signals of other channels refers to the processing process of signals of this channel. As shown in Figure 3, the method includes:

S201. The signal processing apparatus acquires a first relationship between the linear SNR, the nonlinear SNR and a relationship parameter in the optical transmission link, where the relationship parameter is used to reflect the correlation between the upper sideband and the lower sideband of the signal in the optical transmission link The relationship between sex and frequency offset.

Illustratively, the relationship parameter is a droop rate or other parameters obtained by deforming the droop rate, and the droop rate is the droop rate of the correlation between the upper sideband and the lower sideband of the signal in the optical transmission link as the frequency offset increases.

Assuming that the center frequency of a signal is FO, the upper frequency of the signal is the frequency higher than FO in the signal, and the lower frequency of the signal is the frequency lower than FO in the signal. Because the wavelength and frequency of the signal are negatively correlated. Correspondingly, assuming that the center wavelength of the signal is λ, the upper sideband of the signal is the wavelength lower than λ in the signal, and the lower sideband of the signal is the wavelength higher than λ in the signal. FIG. 4 is a schematic diagram of the relationship between the wavelength of a signal and the optical power provided by an embodiment of the present application. Taking the signal X in Fig. 4 as an example, the wavelength range of the signal X is λ1-α to λ1+α, and the center wavelength is λ1, then the wavelength range of the upper sideband of the signal X is λ1-α to λ1, and the wavelength of the lower sideband is λ1-α to λ1. The range is λ1 to λ1+α.

In the same optical transmission system, the correlation of the upper sideband and the lower sideband of the signal transmitted in the optical transmission link varies with the frequency offset. For example, the correlation of the upper sideband and the lower sideband of the signal will vary with the frequency offset. decreases with an increase in , and usually decreases at a fixed rate of decline. The change relationship between the aforementioned correlation and frequency offset (also called the rate of change) is related to the linear SNR and the nonlinear SNR, and the relationship parameters can reflect the change relationship. Therefore, the embodiment of the present application obtains the first relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio, and the relationship parameters in the optical transmission link, so as to determine all parameters in the optical transmission link based on the first relationship in the subsequent process. Linear signal-to-noise ratio and nonlinear signal-to-noise ratio of the signal to be measured (referred to as the target signal in this embodiment of the present application).

In an optional manner, the acquiring process of the first relationship includes the following steps:

A1. The signal processing device determines the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to each of the at least three kinds of signals in the optical transmission link, and obtains at least three pairs of linear signal-to-noise ratio and nonlinear signal-to-noise ratio. The linear SNR and nonlinear SNR corresponding to the three signals are different. For example, if the at least three kinds of signals include N kinds of signals, the at least three pairs of linear SNR and nonlinear SNR include N linear SNRs: SNR _linear1 , SNR _linear2 , . . . SNR _linearN and N nonlinear SNRs Ratio: SNR _nonlinear1 , SNR _nonlinear2 , ... SNR _nonlinearN . Among them, SNR _linear1 and SNR _nonlinear1 are a pair of linear SNR and nonlinear SNR, SNR _linear2 and SNR _nonlinear2 are a pair of linear SNR and nonlinear SNR, and so on, the final acquisition is N pairs Linear signal-to-noise ratio and nonlinear signal-to-noise (SNR _linear , SNR _nonlinear ).

The embodiment of the present application assumes that the at least three signals are all optical signals. The signal processing apparatus can obtain at least three signals with different linear SNRs and nonlinear SNRs in various ways. The embodiments of the present application take the following optional implementation manners as examples for description:

In the first optional implementation, according to the noise accumulation formula and nonlinear theoretical equation of the optical amplifier (such as EDFA), it can be known that the transmit power of the transmitter affects the linear noise (also called Gaussian noise) and non-linear noise of the transmitted signal. Linear noise has an effect, so the at least three signals can be obtained by adjusting the transmit power of the transmitter on the optical transmission link. Correspondingly, the transmit powers of the at least three signals are different.

The aforementioned optical amplifier noise accumulation formula is:

is the power of ASE noise, NF _n is the noise figure of the nth optical amplifier (such as EDFA) in the optical transmission link, and G _n is the nth optical amplifier (such as EDFA) in the optical transmission link The amplification gain multiple of , h is Planck's constant, ν is the channel center frequency, and B _signal is the signal bandwidth.

The aforementioned nonlinear theoretical equation satisfies: let

is the power of the nonlinear noise, which can be obtained by integrating the nonlinear power spectral density of the signal. The nonlinear power spectral density of the signal is obtained by the superposition and summation of the nonlinear power spectral density generated by each fiber in the optical transmission link. Among them, the nonlinear power spectral density generated by the nth fiber is:

in,

Represents the nonlinear power spectral density generated by the nth fiber, G(f) is the power spectrum of the signal, f represents the frequency (also called the frequency domain), L _n , α, β ₂ , and γ are the nth fiber respectively. length, loss coefficient, dispersion coefficient and nonlinear coefficient, exp represents the exponential function with the natural constant e as the base.

An optical transmission system may include a plurality of optical signal nodes, which may also be called transmission nodes (English: Transmission node). For example, the optical signal node is a reconfigurable optical add-on multiplexer drop multiplexer, ROADM). Each optical signal node includes one or more optical devices. For example, one WSS 101 and one optical amplifier 102 in FIG. 1 both belong to one optical signal node. Both the two WSSs 101 and the two optical amplifiers 102 in FIG. 2 belong to one optical signal node. The signal processing device may be arranged in one optical signal node, or may be arranged between two optical signal nodes. The aforementioned transmitter refers to the transmitter upstream of the signal processing device, that is, the signal sent by the transmitter can pass through the signal processing device.

In an optional example, the signal processing apparatus receives the at least three signals respectively by manually adjusting the transmit power of the transmitter. In another optional example, the signal processing apparatus may establish a communication connection with the transmitter, and control the transmitter to adjust the transmit power, so that the signal processing apparatus receives the at least three signals respectively.

In the second optional implementation manner, since the magnification of the optical amplifier affects both the linear noise and nonlinear noise of the signal on the optical transmission link, the magnification of the optical amplifier on the optical transmission link can be adjusted by adjusting the magnification of the optical amplifier. to obtain the at least three signals. Correspondingly, the optical amplifiers corresponding to the at least three signals have different magnifications.

Since the magnification of the optical amplifier behind the signal processing device has little effect on the signal processed by the signal processing device, the aforementioned adjusted optical amplifier is an optical amplifier disposed upstream of the signal processing device. The optical amplifier has a variety of different magnifications, and its magnification is adjustable. In an optional example, the signal processing apparatus receives the at least three signals respectively by manually adjusting the magnification of the optical amplifier. In another optional example, the signal processing apparatus may establish a communication connection with the optical amplifier, and control the optical amplifier to adjust the magnification, so that the signal processing apparatus receives the at least three signals respectively.

In the third optional implementation manner, since different types of optical amplifiers have influence on the linear noise and nonlinear noise of the signal on the optical transmission link, the optical amplifier type on the optical transmission link can be adjusted to obtain the at least three signals. Correspondingly, the types of optical amplifiers corresponding to the at least three signals are different.

Since the type of the optical amplifier located after the signal processing device has little effect on the signal processed by the signal processing device, the aforementioned adjusted optical amplifier is an optical amplifier arranged upstream of the signal processing device. In an optional example, the types of the optical amplifiers are adjusted by manually disassembling and replacing different optical amplifiers, so that the signal processing apparatus respectively receives the at least three kinds of signals. In another optional example, an optical amplifier switching device may be provided on the optical transmission link before the signal processing device, so as to switch different types of optical amplifiers to the optical transmission link, so that the signal processing device respectively receives to the at least three signals. The optical amplifier switching device can be controlled manually or by a signal processing device.

In a fourth optional implementation manner, the at least three signals are acquired by actively loading different noises on the optical transmission link. Correspondingly, the actively loaded noises corresponding to the at least three kinds of signals are different.

For example, a noise adding device may be provided upstream of the signal processing device, for actively adding different noises to the optical transmission link, so that the signal processing device receives the at least three signals respectively. The noise adding device can be controlled manually or by a signal processing device.

In an optional manner, the real value of the linear signal-to-noise ratio can be obtained by the traditional wave drop method or the calculation formula of the linear signal-to-noise ratio. Taking the drop-wave method as an example, assuming that the first signal is any one of the at least three kinds of signals, the process of obtaining the linear signal-to-noise ratio of the first signal includes: turning on the channel transmission of the first signal, and passing the spectrometer at the receiving end. Read the total power s1 of the signal and linear noise in the channel. Then, the channel transmission of the first signal is closed, and the power s2 of the linear noise in the channel is read by the spectrometer at the receiving end. The real value of the linear signal-to-noise ratio of the first signal can be obtained by calculating the obtained two powers. For example, the true value of the linear signal-to-noise ratio of the first signal is equal to s2/(s1-s2).

In an optional manner, the true value of the nonlinear signal-to-noise ratio can be calculated by a theoretical model, for example, the theoretical model is a Gaussian noise model (Guassian noise model, GNmodel) or the aforementioned nonlinear theoretical equation. For another example, the theoretical model is a model approximated to additive Gaussian noise obtained by modeling in the time domain.

Optionally, the nonlinear signal-to-noise ratio can also be obtained by adding a pilot signal to the signal transmitted in the optical transmission link.

A2. The signal processing device obtains the relationship parameters of each of the at least three types of signals.

The embodiment of the present application assumes that the signal processing device is a digital signal processing (Digital signal processing, DSP) device, which is in the digital domain. FIG. 5 and FIG. 6 are schematic diagrams of frequency offset loading principles of the signal processing systems involved in the two signal processing methods provided by the embodiments of the present application, respectively. The signal processing system includes: a coherent receiver 301 and a signal processing device 302 . The coherent receiver 301 is used for receiving the optical signal from the optical transmission link, converting the received optical signal into a digital signal, and sending the converted digital signal to the signal processing device 302; the signal processing device 302 is used for processing the received digital signal . Using a coherent receiver to acquire the optical signal can retain the complete information of the optical signal, which facilitates the subsequent chromatic dispersion (CD) compensation and/or frequency offset loading. The complete information of this optical signal includes the strength and phase of the signal. It is worth noting that, in actual implementation, the coherent receiver can also be replaced by other types of receivers, as long as complete information of the optical signal can be obtained through the other types of reception.

As shown in FIG. 5 , it is assumed that the first signal is any one of at least three kinds of signals transmitted in the optical transmission link. In FIG. 5 , a frequency offset is applied to the first signal in the digital domain (ie, at the signal processing device) to obtain the relationship parameter of the first signal at the signal processing device. In FIG. 6 , a frequency offset is applied to the first signal in the optical domain (ie, at the coherent receiver) to obtain the relationship parameter of the first signal at the signal processing apparatus.

As shown in Figure 5, the process of acquiring the relationship parameter of the first signal includes:

A21. The signal processing apparatus respectively loads at least two different frequency offsets on the first signal in the digital domain to obtain at least two sub-signals.

Assuming that the first signal is an optical signal, the signal processing device receives a digital signal converted from the first signal, and processes the digital signal to realize the processing of the first signal by the signal processing device in the digital domain. The method includes: respectively loading at least two different frequency offsets on the first signal in the digital domain, and the process of loading the frequency offsets can be implemented by a specified algorithm. For example, it is assumed that the first sub-signal is any one of at least two sub-signals obtained by adding at least two carrier frequency offsets to the first signal respectively. The acquisition process of the first sub-signal includes: based on the baud rate of the first signal in the digital domain and the target frequency offset to be introduced, determining an initial phase increment factor, where the initial phase increment factor is the target frequency offset and the first frequency offset. The ratio of the baud rate of the signal; the first sub-signal is obtained by multiplying the symbols in the first signal in the digital domain by the corresponding phase increment factor respectively. Wherein, the phase increment factor corresponding to the qth symbol is the product of the initial phase increment factor and q, 1≤q≤m, and m is the number of symbols in the first signal.

For example, it is assumed that the baud rate of the first signal in the digital domain is 28 GHz, the target frequency offset to be introduced for the first sub-signal is 1 GHz, and the phase increment factor is 1/28. Suppose the first signal is a signal sequence of length m: [A ₁ , A ₂ , A ₃ , A ₄ . . . A _m ], where A _q is the q-th symbol in the first signal, 1≤q≤m . Then, the process of performing frequency offset loading on the first signal in the digital domain includes: multiplying the signal sequence by sequentially corresponding phase increment factors to obtain the following signal sequence, which is the first sub-signal:

[A ₁ ×exp(1i×2π×(1/28)),A ₂ ×exp(1i×2π×(2/28)),A ₃ ×exp(1i×2π×(3/28)),A ₄ ×exp(1i×2π×(4/28)),…A _m ×exp(1i×2π×(m/28))].

Among them, i represents the complex number field, and exp represents the exponential function with the natural constant e as the base.

For the acquisition process of the other sub-signals except the first sub-signal among the aforementioned at least two sub-signals, reference may be made to the acquisition process of the first sub-signal, which is not repeated in this embodiment of the present application.

A22. The signal processing apparatus determines the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals.

In this embodiment of the present application, the upper sideband component (that is, part of the upper sideband) and the lower sideband component (that is, part of the lower sideband) of each sub-signal can be obtained by filtering, and then the correlation between the upper sideband component and the lower sideband component can be obtained. , to determine the correlation between the upper sideband and the lower sideband. In this way, the overall correlation of the upper sideband and the lower sideband can be reflected by the correlation of the parts of the upper sideband and the lower sideband, thereby reducing the computational complexity of the correlation. Illustratively, the process includes: for each of the at least two sub-signals, obtaining an upper sideband component obtained by filtering the sub-signal with an upper sideband component, obtaining a lower sideband component obtained by filtering the sub-signal with a lower sideband component, and converting the upper sideband component. The correlation of the component and the lower sideband component is taken as the correlation of the upper sideband and the lower sideband of the sub-signal. The upper sideband component and the lower sideband component obtained by filtering are respectively a group of time domain signals in the digital domain. The correlation between the upper sideband component and the lower sideband component can be determined through a preset correlation algorithm.

Wherein, the filtering positions of the upper sideband components of the at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering positions of the lower sideband components of the at least two sub-signals are the same, and the filtering bandwidths are the same. That is, the filtering position of the upper sideband component filtering is fixed. The filter position of the lower sideband component filter is fixed. The filtering bandwidth of the upper sideband component filtering of the same sub-signal is the same as the filtering bandwidth of the lower sideband component filtering, so that the correlation between the upper sideband component and the lower sideband component can be determined under the same filtering bandwidth, and there is no need to perform the upper sideband component and the lower sideband component. Alignment of components across the bandwidth reduces the computational complexity of correlation.

The foregoing process of acquiring the upper sideband component and the lower sideband component may be implemented in the digital domain or in the optical domain. FIG. 7 and FIG. 8 are schematic diagrams of filtering principles of the signal processing systems involved in the two signal processing methods provided by the embodiments of the present application, respectively. The signal processing system includes: a coherent receiver 301 and a signal processing device 302 . For the functions of the coherent receiver 301 and the signal processing device 302, refer to the aforementioned FIG. 5 and FIG. 6 . As shown in FIG. 7 , taking the first sub-signal as an example, in FIG. 7 , the upper sideband component and the lower sideband component are obtained by performing upper sideband component filtering and lower sideband component filtering on the first sub signal in the digital domain (ie, at the signal processing device). with component. In an optional implementation manner, the signal processing apparatus may filter the upper sideband and the lower sideband through a digital band-pass filter. Digital bandpass filters are used in the digital domain to allow signals in certain frequency bands to pass, while blocking signals in other frequency bands. Wherein, the position of the digital band-pass filter used to obtain the upper sideband component is f+α ₀ /2 of the first signal, and the position of the digital band-pass filter used to obtain the lower sideband component is f- of the first signal α ₀ /2, where f is the center frequency, and α ₀ is the baud rate of the first signal. Exemplarily, the corresponding position of the center frequency of the first signal is 0 GHz, and the baud rate is 28 GHz. The position of the first digital bandpass filter for filtering the upper sideband component is +14GHz; the position of the second digital bandpass filter for filtering the lower sideband component is -14GHz.

The frequency ranges corresponding to the bandwidth ranges of the first digital band-pass filter and the second digital band-pass filter may be several dozen MHz (megahertz) to several hundreds of MHz, as long as the effective acquisition of the corresponding sideband components is ensured. By sweeping the frequency of the first sub-signal, the filtering of the upper sideband component by the first digital bandpass filter and the filtering of the lower sideband component by the second digital bandpass filter are realized.

As shown in FIG. 8 , taking the first sub-signal as an example, in FIG. 8 , the upper sideband component and the lower sideband component are obtained by filtering the upper sideband component and the lower sideband component of the first subsignal in the electrical domain of the coherent receiver. Correspondingly, the signal processing device 302 receives the upper sideband component and the lower sideband component.

FIG. 9 is a schematic diagram of a filtering principle of a signal processing system involved in a signal processing method based on FIG. 8 provided by an embodiment of the present application. The coherent receiver can filter the upper and lower sidebands through filters. Wherein, the filter for acquiring the upper sideband component and the filter for acquiring the lower sideband component are both low-pass filters (Low-pass filters) whose center frequency is at zero frequency. Among them, the filtering rule of the low-pass filter is that the low-frequency signal can pass normally, and the high-frequency signal exceeding the set threshold value is blocked or weakened. It is assumed in FIG. 9 that the signal processing system includes a first coherent receiver 301a and a second coherent receiver 301b, and the first coherent receiver 301a includes a first local oscillator (Local Oscillator) laser, a first photodetector and a first filter; The second coherent receiver 301b includes a second local oscillator laser, a second photodetector and a second filter. Wherein, the bandwidths of the first filter and the second filter can be in the range of tens of MHz (megahertz) to several hundreds of MHz, as long as the effective acquisition of the corresponding sideband components is ensured. The vibrating laser has a variety of tunable center frequencies. In the coherent detection process of the first coherent receiver 301a, the frequency of the optical signal is swept by the first local oscillator laser to realize the positioning of the upper sideband component, and then the first photodetector performs photoelectric conversion. The low-pass filter filters out the upper sideband component; during the coherent detection process of the second coherent receiver 301b, the optical signal is swept by the second local oscillator laser to locate the lower sideband component, and then the second After the photodetector performs photoelectric conversion, the lower sideband component is filtered out by the second low-pass filter.

The signal processing system in FIG. 9 realizes the filtering of the upper sideband component and the lower sideband component by adjusting the difference between the center frequency of the local oscillator laser and the optical signal. In the first coherent receiver 301a, when the center frequency of the first local oscillator laser is different from the center frequency of the optical signal, the spectrum of the electrical signal converted by the first optical detector based on the optical signal will have a frequency spectrum relative to the zero-frequency origin. offset, and the first filter is always at zero frequency, it can filter out frequencies near the origin. For example, assuming that the baud rate of the optical signal is 28 GHz, when the center frequency of the first local oscillator laser is higher than the center frequency of the optical signal by 14 GHz, the spectrum of the obtained electrical signal will have a 14 GHz offset relative to the zero frequency origin. The first filter filters out the components of the upper sideband. Similarly, when the center frequency of the second local oscillator laser is lower than the center frequency of the optical signal by 14 GHz, what the second filter filters out is the lower sideband component.

It should be noted that there may be other elements in the coherent receiver, and the elements in FIG. 9 are only schematically illustrated.

A23. The signal processing apparatus obtains the relationship parameter of the first signal by fitting based on the at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each sub-signal in the at least two sub-signals.

The relationship parameter of the first signal is used to reflect the relationship between the correlation between the upper sideband and the lower sideband of the first signal and the frequency offset. Based on the obtained at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals, the relationship parameters of the first signal can be obtained by fitting.

It is worth noting that the more types of frequency offsets loaded in the foregoing steps A21 to A23, the higher the accuracy of the relationship parameters obtained by fitting. Exemplarily, the aforementioned at least two types of frequency offsets may include 10 to 30 types of frequency offsets, and the corresponding acquired correlations may include 10 to 30 types of correlations.

Illustratively, the relationship parameter is a drop rate, and FIG. 10 is a schematic diagram of a fitting result of a drop rate of a first signal provided by an embodiment of the present application. In Fig. 10, the horizontal axis represents the frequency offset in GHz, and the vertical axis represents the correlation. Among them, the decline rate can be obtained by introducing different frequency offsets and calculating a series of corresponding correlation values, and then fitting the values of the correlation and frequency offset. The relationship between the correlation and the frequency offset can be represented by a cubic function. After demonstration, if the relationship between the correlation and the frequency offset is represented by other functions such as quadratic function or quartic function, its accuracy is far less than that of cubic function. Therefore, the cubic function can more accurately reflect the relationship between the correlation and the frequency offset. Using the cubic function to describe the relationship between the correlation and the frequency offset can effectively improve the accuracy of the final fitting result.

Exemplarily, the cubic function is a first formula, and the first formula is: y=Ax ³ +Z, where A represents the decline rate, y represents the correlation, x represents the frequency offset, and Z represents the offset introduced by other inherent factors , which is not zero. By way of example, the inherent factors include transmitter-introduced noise, receiver-introduced noise, and/or the resolution of the receiver (eg, a coherent receiver). The obtained at least two frequency offset values and the corresponding correlation values are fitted with the first formula y=Ax ³ +Z to obtain a relationship curve corresponding to the first formula, and the relationship curve is used to reflect that the correlation increases with time. Based on the decreasing trend of the increase of frequency offset, A is obtained based on the relationship curve. In FIG. 10 , a relationship curve obtained by fitting a plurality of data points, each data point represents a value of a frequency offset and a corresponding value of the correlation. A value of a frequency offset corresponds to a value of a correlation, which means that the two belong to the same sub-signal. For example, when the frequency offset is 1GHz, the correlation is 0.8; when the frequency offset is 2GHz, the correlation is 0.7, and the correlation gradually decreases as the frequency offset increases.

As shown in Figure 6, the process of acquiring the relationship parameter of the first signal includes:

A24. The signal processing apparatus receives at least two sub-signals, where the at least two sub-signals are signals obtained by applying at least two different frequency offsets to the first signal.

Exemplarily, the at least two sub-signals are signals obtained by the coherent receiver 301 adding at least two different frequency offsets to the first signal. In an optional implementation manner, the coherent receiver 301 includes a local oscillator laser, and the local oscillator laser has multiple adjustable center frequencies. By changing the center frequency of the local oscillator laser, the coherent receiver 301 can receive The first optical signal is loaded with different frequency offsets, thereby obtaining at least two sub-signals. Correspondingly, the signal processing apparatus receives the at least two sub-signals. For example, in the coherent detection process of the coherent receiver 301, the frequency of the optical signal is swept by the local oscillator laser, so as to realize the frequency offset loading of the optical signal.

In an optional example, the structure of the signal processing system can refer to FIG. 9. During the coherent detection process of the optical signal by the first coherent receiver 301a, the frequency of the optical signal is swept by the first local oscillator laser to realize the detection of the upper sideband. Frequency offset loading of components; in the coherent detection process of the second coherent receiver 301b, the optical signal is swept by the second local oscillator laser to realize the frequency offset loading of the lower sideband component. Assuming that the center frequency of the optical signal is T, the baud rate of the optical signal is E, and the frequency offset to be loaded is L, then the center frequency of the first local oscillator laser is adjusted to be T+L+E/2, so that the upper side of the optical signal is The position of the signal spectrum with the corresponding electrical signal will move L in the positive direction relative to the origin; adjust the center frequency of the second local oscillator laser to T+L-E/2, so that the lower sideband of the optical signal corresponds to the position of the signal spectrum of the electrical signal will move L in the positive direction relative to the origin.

Taking the implementation of frequency offset loading by the coherent receiver shown in Figure 9 as an example, assuming that the center frequency of the optical signal is T, and the baud rate of the optical signal is 28 GHz, it is necessary to load a frequency offset of 1 GHz, and adjust the first local oscillator laser and the second local oscillator. The center frequencies of the two local oscillator lasers are "15 GHz higher than the center frequency of the optical signal" (ie T+15 GHz) and "lower than the center frequency of the optical signal 13 GHz" (ie the center frequency is T-13 GHz). The interval between the center frequencies of the first local oscillator laser and the second local oscillator laser is 28 GHz, which is the baud rate of the optical signal.

For another example, it is assumed that the center frequency of the first signal is T and the baud rate is 28 GHz. When the center frequency of the optical signal of the first local oscillator laser is T+14GHz, and the center frequency of the optical signal of the second local oscillator laser is T-14GHz, the upper sideband component filtered by the first filter and the second filter The signal filtered by the lower sideband component is the electrical signal corresponding to the first signal (that is, the frequency offset is not loaded, also called the loaded frequency offset is 0); when the center frequency of the optical signal of the first local oscillator laser is T +15GHz, when the center frequency of the optical signal of the second local oscillator laser is T-13GHz, the signal filtered by the upper sideband component and the lower sideband component filtered by the first filter and the second filter is the first signal loaded with 1GHz The electrical signal corresponding to the frequency deviation; when the center frequency of the optical signal of the first local oscillator laser is T+16GHz, and the center frequency of the optical signal of the second local oscillator laser is T-12GHz, the first filter and the second filter pass through the first filter and the second filter. The filtered signals of the upper sideband component and the lower sideband component are the electrical signals corresponding to the first signal loaded with a frequency offset of 2 GHz.

It should be noted that the foregoing embodiments only take the example of the signal processing system including two coherent receivers, and the example of frequency offset loading in the optical domain for description. In actual implementation, the signal processing system can also use one coherent receiver or three or four coherent receivers to implement frequency offset loading. For different numbers of coherent receivers, the method of performing frequency offset loading by adjusting the center frequency of the local oscillator laser in the coherent receiver should be covered by the protection scope of the embodiments of the present application.

A25. The signal processing apparatus determines the correlation between the upper sideband and the upper sideband of each of the at least two sub-signals.

For step A25, reference may be made to the aforementioned A22, which is not described repeatedly in this embodiment of the present application.

A26. The signal processing apparatus obtains the relationship parameter of the first signal by fitting based on the at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each sub-signal in the at least two sub-signals.

For step A26, reference may be made to the aforementioned A23, which is not repeated in this embodiment of the present application.

It should be noted that, referring to the aforementioned FIG. 5 to FIG. 9 , the target signal transmitted in the optical transmission link is an optical signal, and the signal processing device receives a digital signal converted from the optical signal. In an optical transmission link, chromatic dispersion will cause a certain delay to signals of different frequencies, and the upper and lower sidebands of the same signal correspond to different frequencies. During the transmission process, the upper and lower sidebands will An offset in the time domain is generated, which will affect the subsequently determined accuracy of the correlation between the upper and lower sidebands of the same signal, thereby affecting the detection accuracy of the relationship parameter. Therefore, after receiving the digital signal, the signal processing device firstly performs chromatic dispersion compensation on the received digital signal to obtain a digital signal after chromatic dispersion compensation. The chromatic dispersion compensation refers to compensating the phase of the digital signal. After that, the signal processing apparatus acquires the relational parameters of the digital signal after chromatic dispersion compensation. That is, before the aforementioned A21 or A24, the signal processing device needs to perform chromatic dispersion compensation on the received digital signal, thus realizing the time calibration of the digital signal, thereby improving the accuracy of the acquired relational parameters. Among them, the chromatic dispersion compensation can be realized by correcting the phase of the received signal by using a time-domain digital filter or a frequency-domain digital equalizer.

A3. The signal processing apparatus obtains the first relationship by fitting based on at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the obtained relationship parameters.

As described in A2 above, for each of the at least three signals, its relationship parameters are obtained. For example, the decline rate of each signal is obtained, still taking Fig. 10 as an example, assuming that the aforementioned at least three signals have a total of N signals, the first formula is used: y=Ax ³ +Z to fit the obtained decline rate of a total of N A ₁ , A ₂ ,...A _N , respectively. And, for each of the aforementioned at least three signals, its linear signal-to-noise ratio and its nonlinear signal-to-noise ratio are obtained.

Both linear noise and nonlinear noise will destroy the correlation between the upper and lower sidebands of the signal spectrum. However, linear noise is spectrally flat, while nonlinear noise is not spectrally flat. Therefore, when there is a frequency offset, the influence of linear noise and nonlinear noise on the correlation of the upper and lower sidebands of the spectrum is also different. , so a binary linear equation can be established to reflect the first relationship between the correlation between the linear SNR and the nonlinear SNR and the frequency. Exemplarily, the first relationship may be represented by the following first relationship:

Among them, A represents the relationship parameter, SNR _linear represents the linear SNR, SNR _nonlinear represents the nonlinear SNR, B ₁ represents the contribution of the linear noise to the relationship parameter A, and B ₂ represents the contribution of the nonlinear noise to the relationship parameter A. , _B3 represents the bias introduced by other inherent factors. By way of example, the inherent factors include transmitter-introduced noise, receiver-introduced noise, and/or the resolution of the receiver (eg, a coherent receiver).

Before fitting, at least three pairs of linear signal-to-noise ratio and nonlinear signal-to-noise ratio, and the obtained relationship parameter A are known numbers; B ₁ , B ₂ and B ₃ are unknown numbers. By combining at least three pairs of linear SNR and nonlinear SNR (such as the aforementioned N pairs of linear SNR and nonlinear SNR), and the obtained relationship parameters (such as the aforementioned A ₁ , A ₂ , ... A _N ) Substituting into the first relational expression, B ₁ , B ₂ and B ₃ can be obtained by fitting. Substituting the fitted B ₁ , B ₂ and B ₃ into the first relational expression, the first relational expression with known coefficients can be obtained.

S202. The signal processing apparatus acquires the second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link.

In the same optical transmission system, the linear signal-to-noise ratio and nonlinear signal-to-noise ratio corresponding to the signal of the optical transmission link are correlated with the signal-to-noise ratio. In this embodiment of the present application, by acquiring the second relationship of the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio, and the signal-to-noise ratio in the optical transmission link, in the subsequent process, based on the second relationship, the required information in the optical transmission link is determined. Linear signal-to-noise ratio and nonlinear signal-to-noise ratio of the measured signal (referred to as the target signal in the embodiment of this application).

In an optional manner, the acquiring process of the second relationship includes the following steps:

B1. The signal processing device determines the linear SNR and the nonlinear SNR corresponding to each of the at least three types of signals in the optical transmission link, and obtains at least three pairs of linear SNR and nonlinear SNR, at least three The corresponding linear SNR and nonlinear SNR are different for the signal.

For step B1, reference may be made to the foregoing step A1, which is not repeated in this embodiment of the present application. It should be noted that at least three kinds of signals in B1 and at least three kinds of signals in A1 may be the same or different. When at least three kinds of signals in B1 are the same as at least three kinds of signals in A1, the signal acquisition process can be reduced, and the processing steps can be simplified.

B2. The signal processing apparatus acquires the signal-to-noise ratio of each of the at least three kinds of signals.

This signal-to-noise ratio is the overall signal-to-noise ratio. The signal-to-noise ratio of each signal is the signal-to-noise ratio when the frequency offset is not loaded, that is, the signal-to-noise ratio of each signal when the frequency offset loaded in both the optical domain and the digital domain is 0. In this embodiment of the present application, a traditional method for obtaining a signal-to-noise ratio may be used to obtain the signal-to-noise ratio of each of the at least three signals. For example, an out-of-band interpolation method or an error vector magnitude calculation method or an SNR monitoring method based on the correlation of upper and lower spectrum sidebands of a signal, or a theoretical model calculation or other algorithm based on channel parameters can be used to determine the signal-to-noise ratio. Exemplarily, assuming that the aforementioned at least three kinds of signals include N kinds of signals, as long as for each received signal, the aforementioned method is used to obtain the SNR when the frequency offset is set to 0, and a series of SNR measurements can be obtained. Values: SNR _meas1 , SNR _meas2 ,…SNR _measN .

FIG. 11 is a schematic diagram of the principle of calculating the signal-to-noise ratio of a signal by using an out-of-band interpolation method according to an embodiment of the present application. The spectrum shown in Figure 11 can be monitored by a spectrometer. In-band refers to the area occupied by the signal spectrum, that is, within the bandwidth of the signal. As shown in FIG. 11 , assuming that the target signal is a signal X, the in-band of the signal X refers to the region in the wavelength range of λ1-α to λ1+α, and the out-of-band refers to outside the bandwidth of the signal. The out-of-band difference method refers to interpolating the in-band noise by the out-of-band noise on both sides of the signal X, and the in-band noise obtained by interpolation (such as linear interpolation) and the sum of the signal and noise at the center frequency of the signal X. Power determines the signal-to-noise ratio. Assuming that the out-of-band noise is amplified spontaneous emission (ASE) noise, the out-of-band noise in the upper sideband of the signal X is ASE1, and the out-of-band noise in the lower sideband is ASE2, then the in-band noise ASE3 = (ASE1 +ASE2)/2; Assuming that the total power of the signal and noise at the center frequency of the signal X is M, the signal-to-noise ratio is (M-ASE3)/ASE3.

FIG. 12 is a schematic diagram of the principle of calculating the signal-to-noise ratio of a signal by using an error vector magnitude calculation method according to an embodiment of the present application. The horizontal axis of FIG. 12 represents the I channel, that is, the real part, the vertical axis represents the Q channel, that is, the imaginary part, and the circle represents the constellation diagram of the received signal. Suppose the received signal is represented by a signal sequence of length u: [A1, A2, A3, A4...Au], that is, the signal sequence includes u symbols, each symbol corresponds to a signal in the received signal, rk represents the magnitude of the position vector of the kth signal after the constellation diagram of the received signal is recovered. 1≤k≤u. sk represents the magnitude of the position vector of the kth signal located on the constellation diagram after signal decision (for example, for Quadrature phase shift keying (QPSK) signal, it can be decided as 1+1i, 1- 1i, -1+1i, -1-1i four cases, in this case, the vector magnitude is equivalent to the root sign 2). nk represents the magnitude of the noise vector received by the kth signal, which can be calculated by connecting the sk terminal and the rk terminal. The average power of the signal can be expressed by averaging the square of the sk of each of the u symbols. The average power of the noise can be expressed by averaging the square of nk for each of the u symbols. The signal-to-noise ratio is then obtained by dividing the average power of the signal by the average power of the noise.

The process of determining the SNR by the SNR monitoring method based on the correlation of the upper and lower sidebands of the spectrum of the signal may include: determining the SNR based on the SNR calculation formula, where the SNR calculation formula is:

Among them, SNR _meas represents the signal-to-noise ratio, that is, the overall signal-to-noise ratio, f represents the frequency, _PS represents the signal power, and _PN represents the noise power. B _meas is the measurement bandwidth of the signal (that is, the measurement bandwidth of the target signal), E[] means averaging in the time domain,

Represents the correlation between the upper sideband and the lower sideband of the signal with the center frequency at _fc and the interval between the maximum frequency and the minimum frequency is α ₀ (eg, the correlation calculated using the upper and lower sideband components). The aforementioned signal-to-noise ratio calculation formula is determined by the correlation

The principle of the correlation with SNR _meas is derived. in,

represents the total power of the signal and noise in the measurement bandwidth to be monitored (ie the aforementioned measurement bandwidth B _meas ), t represents the time (also called the time domain),

Indicates that under the premise of a flat noise spectrum, the noise power at f _c ±α ₀ /2 is extended to the total power of the entire measurement bandwidth, and the -1 after that is due to the need to remove the noise existing in the molecule to meet the signal-to-noise ratio Definition.

For traditional sparse wavelength division multiplexing and point-to-point optical transmission systems, the SNR determined by the out-of-band interpolation method is more accurate. However, with the application of ROADM, the out-of-band ASE noise and in-band ASE noise may be different, which easily affects the reliability of the signal-to-noise ratio; in addition, for the optical transmission system of dense wavelength division multiplexing, the noise between adjacent channels cannot be Efficiently read, so the signal-to-noise ratio cannot be effectively obtained. However, the SNR monitoring method based on the correlation of the upper and lower sidebands of the signal spectrum determines the SNR, which is not affected by in-band or out-of-band, and is not affected by the dense wavelength division multiplexing system, and the obtained signal-to-noise ratio is reliable.

In the process of using the error vector magnitude calculation method to obtain the signal-to-noise ratio, the signal needs to be completely solved, so all DSP processes need to be carried out, and the power consumption is high. The modulation format of the DSP, the versatility of different modulation formats is low. For example, in an optical transmission system, under one modulation format, one signal represents 4 bits of data; under another modulation format, one signal represents 8 bits of data. The modulation format of the DSP needs to be configured separately for these two modulation formats. In addition, this method may introduce noise from DSP. The SNR monitoring method based on the correlation of the upper and lower sidebands of the signal spectrum to determine the SNR does not need to completely solve the signal, and does not need to perform all DSP processes, reduce power consumption, and does not limit the modulation formats supported by DSP. Gain flexibility.

B3. The signal processing apparatus obtains a second relationship by fitting based on at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the acquired signal-to-noise ratios.

Because both linear noise and nonlinear noise will have an impact on the overall signal-to-noise ratio (for example, the SNR monitoring method based on the correlation of the upper and lower sidebands of the signal spectrum to determine the signal-to-noise ratio) when there is no frequency offset, but the upper and lower sideband signals The nonlinear noise is not as uncorrelated as Gaussian noise, nor has the same strong correlation as the signal itself, so the nonlinear noise does not have no contribution to the overall signal-to-noise ratio, but the contribution is not as linear as Just as loud. Therefore, a quadratic linear equation can be established to reflect the second relationship between the linear SNR and the nonlinear SNR and SNR. Exemplarily, the second relationship may be represented by the following second relationship:

Among them, SNR _meas represents signal-to-noise ratio, SNR _linear represents linear signal-to-noise ratio, SNR _nonlinear represents nonlinear signal-to-noise ratio, C ₁ represents the contribution of linear noise to SNR _meas , and C ₂ represents nonlinear noise to nonlinear The contribution of the SNR _nonlinear to the signal-to-noise ratio, C ₃ represents the bias introduced by other inherent factors.

Before fitting, at least three pairs of linear SNR and nonlinear SNR, and the acquired SNR are known; C ₁ , C ₂ and C ₃ are unknowns. By substituting at least three pairs of linear signal-to-noise ratio and nonlinear signal-to-noise ratio, and the obtained signal-to-noise ratio into the second relationship, C ₁ , C ₂ and C ₃ can be obtained by fitting. Substituting the fitted C ₁ , C ₂ and C ₃ into the second relational expression, the second relational expression with known coefficients can be obtained.

S203. The signal processing apparatus detects the target relationship parameter of the target signal received through the optical transmission link.

The target relationship parameter is the relationship parameter of the target signal. Referring to the aforementioned FIG. 5 to FIG. 9 , the target signal transmitted in the optical transmission link is an optical signal, and the signal processing apparatus receives a digital signal converted from the optical signal. In the optical transmission link, chromatic dispersion will cause a certain time delay to signals of different frequencies, and the upper and lower sidebands of the target signal correspond to different frequencies. During the transmission process, the upper and lower sidebands will generate time domain This will affect the accuracy of the correlation of the upper and lower sidebands of the determined target signal, thereby affecting the detection accuracy of the target relationship parameters. Therefore, after receiving the digital signal, the signal processing apparatus performs chromatic dispersion compensation on the received digital signal to obtain a digital signal after chromatic dispersion compensation. After that, the signal processing device detects the relationship parameter of the digital signal after chromatic dispersion compensation, and obtains the target relationship parameter. In this way, the time calibration of the digital signal is realized, so that the accuracy of the acquired target relationship parameter can be improved.

S204. The signal processing apparatus acquires the target signal-to-noise ratio of the target signal.

In the embodiment of the present application, the signal processing apparatus may obtain the signal-to-noise ratio of the target signal by adopting a traditional method for obtaining the signal-to-noise ratio, so as to obtain the target signal-to-noise ratio. For example, an out-of-band interpolation method or an error vector magnitude calculation method or an SNR monitoring method based on the correlation of upper and lower spectrum sidebands of a signal, or a theoretical model calculation or other algorithm based on channel parameters can be used to determine the target SNR. For the process of obtaining the target signal-to-noise ratio, reference may be made to the process of obtaining the signal-to-noise ratio of the signal in the foregoing step B2.

It is worth noting that the signal-to-noise ratio acquisition method used by the signal processing device to obtain the signal-to-noise ratio of each of the at least three kinds of signals and to obtain the target signal-to-noise ratio can be the same, so that it can offset the effects introduced by other inherent factors in the optical transmission link. interference, so as to obtain more accurate linear SNR and nonlinear SNR in the subsequent process.

Optionally, the signal processing apparatus adopts the SNR monitoring method based on the correlation of upper and lower frequency spectrum sidebands of the signal to obtain the target SNR. Using this method to obtain the target signal-to-noise ratio has high accuracy and simple calculation.

S205. The signal processing apparatus determines the linear SNR corresponding to the target signal and the nonlinear SNR corresponding to the target signal based on the target relationship parameter, the target SNR, the first relationship and the second relationship.

Referring to the aforementioned steps A3 and B3, the first relationship is represented by the independent variables being the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio, the dependent variable is the first relational expression of the relationship parameters, and the second relationship is represented by the independent variables being the linear signal-to-noise ratio and Non-linear signal-to-noise ratio, the dependent variable is represented by the second relational expression of the signal-to-noise ratio, the signal processing device substitutes the target relational parameters into the first relational expression, and substitutes the target signal-to-noise ratio into the second relational expression, that is, the known number is the target relational expression parameters and the target signal-to-noise ratio, the unknowns are the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal, and the linear signal-to-noise ratio corresponding to the target signal and the target signal can be obtained by solving the quadratic linear equation system. The nonlinear signal-to-noise ratio.

In the embodiment of the present application, the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal are obtained by solving the equation, the obtaining method is simple and fast, and the operation efficiency is high.

It is worth noting that the aforementioned first relational expression is established by using correlation and the relation between linear SNR and nonlinear SNR; the second relational expression is established using SNR, linear SNR and nonlinear SNR. The relationship between the noise ratios is established; therefore, the aforementioned first relationship can be deformed based on the correlation and the relationship between the linear SNR and the nonlinear SNR to obtain other forms of relationships; the aforementioned second relationship Other forms of relational expressions can be obtained by deforming based on the relationship between the SNR and the linear SNR and the nonlinear SNR. As long as a binary linear equation system with linear SNR and nonlinear SNR as variables can be established based on the obtained relationship, the linear and nonlinear SNR can be realized by using this binary linear equation system for the received target signal. joint monitoring.

In another implementation manner, since linear noise has a negative correlation (eg, reciprocal relationship) with linear SNR, and nonlinear noise has a negative correlation (eg, reciprocal relationship) with nonlinear SNR, therefore, the aforementioned The first relational expression may also be established using the correlation and the relation between the linear noise and the nonlinear noise; the second relational expression is established using the signal-to-noise ratio and the relation between the linear noise and the nonlinear noise. Based on the obtained relational expressions, a binary linear equation system with linear noise and nonlinear noise as variables is established, and the linear and nonlinear noises are jointly monitored for the received target signal by using this binary linear equation system. Linear Noise and Nonlinear Noise Obtain the linear and nonlinear SNR.

The operation and reconstruction of the signal on the optical transmission link depends on the quality of the optical transmission link, and the accurate optical signal-to-noise ratio can reflect the quality of the optical transmission link. The optical signal-to-noise ratio actually includes the linear signal-to-noise ratio caused by the optical amplifier and the like and the nonlinear signal-to-noise ratio caused by the optical transmission link itself (such as an optical fiber). Since the embodiment of the present application effectively distinguishes the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the target signal, the acquisition granularity of the signal-to-noise ratio is refined. In practical applications, the monitoring and maintenance of the optical transmission system can be performed based on the linear SNR and the nonlinear SNR corresponding to the acquired target signal. For example, after the linear signal-to-noise ratio corresponding to the target signal is greater than the linear signal-to-noise ratio threshold, the signal processing device determines that the optical amplifier in the optical transmission link upstream of the signal processing device is at risk of failure, and the signal processing device may issue the first alarm information , indicating that the optical amplifier in the optical transmission link upstream of the signal processing device is at risk of failure, so as to facilitate the maintenance or replacement of the optical amplifier by the staff. For another example, after the nonlinear signal-to-noise ratio corresponding to the target signal is greater than the nonlinear signal-to-noise ratio threshold, the signal processing device determines that the optical transmission link (such as an optical fiber) upstream of the signal processing device is at risk of failure, and the signal processing device can send the first signal. Two alarm information, indicating that the optical transmission link upstream of the signal processing device has a risk of failure, so as to facilitate the maintenance or replacement of the optical transmission link by the staff.

It should be noted that, in the foregoing embodiments, the signal processing device is respectively introduced to perform upper sideband component filtering and lower sideband component filtering (refer to the corresponding explanation in FIG. 7 ), and the signal processing device performs frequency offset loading (refer to the corresponding explanation in FIG. 5 ) ; The coherent receiver performs upper sideband component filtering and lower sideband component filtering (refer to the explanations corresponding to Figures 8 and 9), and the coherent receiver performs frequency offset loading (refer to the explanations corresponding to Figures 6 and 9) and other signal processing methods processes involved. In actual implementation, the implementation of the signal processing method may include the following combinations: the signal processing device performs upper sideband component filtering and lower sideband component filtering, and the signal processing device performs frequency offset loading; or, the coherent receiver performs upper sideband component filtering. and lower sideband component filtering, and the coherent receiver performs frequency offset loading; or, the signal processing device performs upper sideband component filtering and lower sideband component filtering, and the coherent receiver performs frequency offset loading; or, the coherent receiver performs upper sideband component filtering. and the lower sideband components are filtered, and the signal processing device performs frequency offset loading. Any method obtained by simple deformation on the basis of the aforementioned combination should be included within the protection scope of the present application.

To sum up, according to the different characteristics of the flat linear noise spectrum and the non-flat nonlinear noise spectrum, the embodiment of the present application establishes the first relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the relationship parameters in the optical transmission link, and The second relationship between the linear SNR, the nonlinear SNR and the SNR in the optical transmission link, and based on these two relationships, the actual acquired target relationship parameters and the target SNR are used to determine the corresponding target signal. Linear signal-to-noise ratio and nonlinear signal-to-noise ratio, so as to realize the effective distinction between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal.

In addition, the embodiment of the present application can simultaneously acquire the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal, and the acquisition efficiency of the signal-to-noise ratio is high, which is convenient for the staff to conduct a comprehensive and effective analysis of the transmission quality of the optical transmission link.

Further, the signal processing method provided by the embodiment of the present application does not limit the modulation format supported by the DSP, and can support the monitoring of the linear SNR and the nonlinear SNR of signals of different modulation formats, thereby improving the monitoring flexibility. .

As described in the aforementioned step A2, the nonlinear signal-to-noise ratio can also be obtained by adding a pilot signal to the signal transmitted in the optical transmission link, but this will sacrifice spectral efficiency and system flexibility. However, in the embodiment of the present application, once the first relationship and the second relationship are obtained, the linear noise and the nonlinear noise can be obtained by solving the quadratic linear equation system, the flexibility of obtaining the signal-to-noise ratio is high, and the The impact of spectral efficiency and system flexibility.

Referring to FIG. 12 , when the traditional error vector magnitude calculation method is used to calculate the signal-to-noise ratio of a signal, the signal needs to be completely recovered, and the complexity of obtaining the signal-to-noise ratio of the signal is relatively high. The signal-to-noise ratio can be obtained in a way without completely restoring the signal, which effectively reduces the complexity of obtaining the signal-to-noise ratio.

It should be noted that the sequence of steps of the signal processing method provided by the embodiments of the present application can be appropriately adjusted, and the steps can also be increased or decreased according to the situation. Any person skilled in the art is within the technical scope disclosed in this application, Variations of methods that can easily be conceived should be included within the scope of protection of the present application. Exemplarily, the aforementioned S201 and S202 may be acquired during the networking of the optical transmission system (or after the optical transmission system is initialized), and then perform S203 to S205 during the subsequent signal transmission process of the optical transmission link; or, in the optical transmission chain During the process of signal transmission by the channel, S201 to S205 are executed. Optionally, the signal processing apparatus may also periodically execute the S201 and S202, so that the latest first relationship and the second relationship can be acquired, ensuring that the linear SNR and the nonlinear SNR obtained by monitoring follow the optical transmission link. It is updated as the quality changes, improving the accuracy of the determined linear SNR and nonlinear SNR.

FIG. 13 is a schematic structural diagram of a signal processing apparatus 40 provided by an embodiment of the present application. As shown in FIG. 13 , the apparatus 40 includes:

The first relationship obtaining module 401 is used to obtain the first relationship between the linear SNR, the nonlinear SNR and the relationship parameter in the optical transmission link, and the relationship parameter is used to reflect the upper sideband and the lower edge of the signal in the optical transmission link The relationship between the correlation of the band and the frequency offset; the second relationship obtaining module 402 is used to obtain the second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link; the parameter obtaining module 403, used to obtain the target relationship parameter of the target signal received through the optical transmission link; the signal-to-noise ratio acquisition module 404 is used to obtain the target signal-to-noise ratio of the target signal; the determination module 405 is used to obtain the target signal-to-noise ratio based on the target relationship parameter, the target signal-to-noise ratio , the first relationship and the second relationship, to determine the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal.

To sum up, in the present application, the first relationship between the linear SNR, the nonlinear SNR and the relationship parameters in the optical transmission link is established by the first relationship acquisition module, and the second relationship acquisition module is used to establish the first relationship in the optical transmission link. The second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio, and the determination module determines the linear signal corresponding to the target signal by using the actually obtained target relationship parameters and target signal-to-noise ratio based on these two relations. Noise ratio and nonlinear signal-to-noise ratio, so as to realize the effective distinction between the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the signal.

In an optional example, the first relationship is represented by a first relationship whose independent variables are linear signal-to-noise ratio and nonlinear signal-to-noise ratio, the dependent variable is a relationship parameter, and the second relationship is represented by the independent variables of linear signal-to-noise ratio and The nonlinear signal-to-noise ratio, the dependent variable is represented by the second relational expression of the signal-to-noise ratio, and the determination module 405 is used for: substituting the target relational parameters into the first relational expression, substituting the target signal-to-noise ratio into the second relational expression, and by solving the second relation The linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal are obtained from the system of first-order equations.

In an optional example, the target signal received through the optical transmission link is an optical signal, and the parameter acquisition module 403 is configured to: perform chromatic dispersion compensation on the digital signal, and the digital signal is obtained by converting the optical signal; detect chromatic dispersion; The relationship parameter of the compensated digital signal is obtained to obtain the target relationship parameter.

FIG. 14 is a schematic structural diagram of a first relationship obtaining module 401 provided by an embodiment of the present application. As shown in Figure 14, the first relationship acquisition module 401 includes:

The determination sub-module 4011 is configured to determine the linear SNR and the nonlinear SNR corresponding to each of the at least three signals in the optical transmission link, and obtain at least three pairs of the linear SNR and the nonlinear SNR, The linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to the at least three kinds of signals are different; the obtaining sub-module 4012 is used to obtain the relationship parameters of each of the at least three kinds of signals; the fitting sub-module 4013 is used to The first relationship is obtained by fitting the linear SNR and the nonlinear SNR, and the obtained relationship parameters.

Optionally, the acquiring sub-module 4012 is configured to: respectively load at least two different frequency offsets on the first signal in the digital domain to obtain at least two sub-signals, or receive at least two sub-signals, where the at least two sub-signals are for the first signal. A signal is a signal obtained by loading at least two different frequency offsets, and the first signal is any one of the at least three signals; determining the correlation between the upper sideband and the lower sideband of each sub-signal in the at least two sub-signals; The two frequency offsets, and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals, are fitted to obtain the relationship parameter of the first signal.

Further, obtaining sub-module 4012 is used for: for each kind of sub-signal in at least two kinds of sub-signals, obtaining the upper sideband component obtained by filtering the upper sideband component of the sub-signal, and obtaining the lower sideband component obtained by filtering the lower sideband component of the sub-signal , the correlation between the upper sideband component and the lower sideband component is taken as the correlation between the upper sideband and the lower sideband of the sub-signal; wherein, the filtering positions of the upper sideband components of at least two sub-signals are the same, and the filtering bandwidth is the same; at least two sub-signals The filtering position of the lower sideband component of the same sub-signal is the same, and the filtering bandwidth is the same; the filtering bandwidth of the upper sideband component filtering of the same sub-signal is the same as the filtering bandwidth of the lower sideband component filtering.

In an optional example, the second relationship obtaining module 402 is configured to: determine the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to each of the at least three kinds of signals in the optical transmission link, and obtain at least three pairs of linear Signal-to-noise ratio and nonlinear signal-to-noise ratio, the linear signal-to-noise ratio and nonlinear signal-to-noise ratio corresponding to at least three kinds of signals are different; obtain the signal-to-noise ratio of each of at least three kinds of signals; based on at least three pairs of linear signal-to-noise ratio ratio and the nonlinear signal-to-noise ratio, as well as the obtained signal-to-noise ratio, are fitted to obtain a second relationship.

Optionally, the at least three signals are different in at least one of the following parameters: transmit power, magnification of the corresponding optical amplifier, type of the corresponding optical amplifier, or actively loaded noise.

It is worth noting that the relationship parameter may be a drop rate, and the drop rate is the drop rate of the correlation between the upper sideband and the lower sideband of the signal in the optical transmission link as the frequency offset increases.

FIG. 15 is a possible basic hardware architecture of the computer device provided by the embodiment of the present application. The computer equipment may be the aforementioned signal processing apparatus. Referring to FIG. 15, a computer device 500 includes a processor 501, a memory 502, a communication interface 503, and a bus 504.

In the computer device 500, the number of processors 501 may be one or more, and FIG. 15 only illustrates one of the processors 501. Optionally, the processor 501 may be a central processing unit (central processing unit, CPU). If the computer device 500 has multiple processors 501, the multiple processors 501 may be of different types, or may be the same. Optionally, the multiple processors 501 of the computer device 500 may also be integrated into a multi-core processor.

The memory 502 stores computer instructions and data; the memory 502 may store computer instructions and data required to implement the signal processing methods provided herein, for example, the memory 502 stores instructions for implementing the steps of the signal processing methods. The memory 502 may be any one or any combination of the following storage media: non-volatile memory (eg read only memory (ROM), solid state drive (SSD), hard disk (HDD), optical disk), volatile memory.

The communication interface 503 may be any one or any combination of the following devices: a network interface (eg, an Ethernet interface), a wireless network card, and other devices with a network access function.

The communication interface 503 is used for data communication between the computer device 500 and other computer devices or terminals.

A bus 504 may connect the processor 501 with the memory 502 and the communication interface 503 . In this way, through the bus 504, the processor 501 can access the memory 502, and can also use the communication interface 503 to perform data interaction with other computer devices or terminals.

In the present application, the computer device 500 executes the computer instructions in the memory 502, so that the computer device 500 implements the signal processing method provided in the present application, or causes the computer device 500 to deploy a database system.

In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory including instructions, and the instructions can be executed by a processor of a server to complete the signal processing shown in the various embodiments of the present application. method. For example, the non-transitory computer-readable storage medium may be ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, optical data storage device, and the like.

FIG. 16 is a schematic structural diagram of a signal processing system 60 provided by an embodiment of the present application. As shown in FIG. 16 , the signal processing system 60 includes: a coherent receiver 601 and a signal processing apparatus 602 provided by an embodiment of the present application. The signal processing apparatus 602 may be the aforementioned signal processing apparatus 40 or the aforementioned computer equipment 500 . For the structure of the signal processing system 60, reference may be made to the structure of the signal processing system described in any of the foregoing FIG. 5 to FIG. 9 .

The coherent receiver 601 is configured to receive an optical signal from an optical transmission link, convert the received optical signal into a digital signal, and send the converted digital signal to a signal processing device. Using the coherent receiver to acquire the optical signal can retain the complete information of the optical signal, which is convenient for the signal processing device to perform chromatic dispersion compensation and/or frequency offset loading. In actual implementation, the coherent receiver can also be replaced by other types of receivers, as long as complete information of the optical signal can be obtained through the other types of reception.

Further, the coherent receiver 601 is used to download the optical signal from the optical transmission link through coherent light, and convert the downloaded optical signal into two optical signals whose polarization directions are perpendicular to each other, and then into two digital signals, so as to convert the optical signal into two digital signals. The two channels of digital signals are sent to the signal processing device, and correspondingly, the signal processing device 602 respectively processes the two channels of digital signals to obtain the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to each channel of digital signal. The foregoing S201 to S205 are described by taking one of the two channels of digital signals as an example. In actual implementation, the foregoing S201 to S205 are executed for the two channels of digital signals.

There may be various structures of the coherent receiver 601, and the following two optional implementation manners are used as examples for description in this embodiment of the present application.

FIG. 17 is a schematic structural diagram of a signal processing system 60 provided by an embodiment of the present application, wherein the coherent receiver 601 includes:

The local oscillator laser 6011 is used to generate coherent light and input the coherent light to the polarization beam splitter 6012 . The center frequency of the local oscillator laser 6011 is the same as the center frequency of the target signal to be detected, so under the action of the local oscillator laser 6011, the target signal can be downloaded. For example, as shown in Figure 4, if the target signal to be downloaded is signal X, the center wavelength of the local oscillator laser 6011 is the same as the center wavelength of signal X; if the target signal to be downloaded is signal Y, then the center wavelength of the local oscillator laser 6011 The center wavelength is the same as the center wavelength of signal Y.

The polarization beam splitter 6012 is used to divide the received optical signal (that is, the optical signal transmitted by the optical transmission link) into mutually perpendicular first polarized light and second polarized light, and divide the coherent light into mutually perpendicular third polarized light polarized light and fourth polarized light.

Two 90° mixers 6013, wherein one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light frequency. Wherein, the polarization directions of the first polarized light and the third polarized light are the same, and the polarization directions of the second polarized light and the fourth polarized light are the same; or, the polarization directions of the first polarized light and the third polarized light are different, and the second polarized light and the polarization direction of the fourth polarized light is different. Exemplarily, the first polarized light and the third polarized light are both x-polarized light, and the second polarized light and the fourth polarized light are both y-polarized light.

The photodetector 6014 is used to convert the optical signals output by the two 90° mixers into analog currents. The photodetector 6014 can be a balanced photodetector, and the use of the balanced photodetector 6014 can achieve noise cancellation and reduce noise in the output analog current. The photodetector outputs 4 real signals, which are the x-polarized I (real part) signal, the x-polarized Q (imaginary) signal, the y-polarized I signal, and the y-polarized Q signal. road signal.

The filter 6015 is used for filtering the analog current to obtain the electrical signal corresponding to the target signal. Referring to FIG. 4 , there may be multiple signals with different center wavelengths transmitted on the optical transmission link, and the signal that the signal processing system actually needs to monitor may only be a target signal among the multiple signals, so the target signal needs to be targeted. to be processed. Assuming that the target signal is X, the filter 6015 can filter out the electrical signal corresponding to the target signal X from the analog currents corresponding to the multiple signals. The filter 6015 outputs 4 real-number signals, which are the filtered x-polarized I-channel signal, the filtered x-polarized Q-channel signal, the filtered y-polarized I-channel signal, and the filtered y-polarized signal. the Q-channel signal.

The analog-to-digital converter 6016 is used to convert the electrical signal corresponding to the target signal into a digital signal. For example, the analog-to-digital converter 6016 obtains a digital signal by sampling the electrical signal corresponding to the target signal. The analog-to-digital converter 6016 is also used for inputting the converted digital signal into the signal processing device 602 . The analog-to-digital converter 6016 outputs two complex signals, which are x-polarized signals and y-polarized signals respectively. Wherein, the x-polarized signal is obtained by sampling the complex signal composed of the filtered x-polarized I-channel signal and the filtered x-polarized Q-channel signal, and the y-polarized signal is the filtered y-polarized I-channel signal. The complex signal composed of the channel signal and the filtered y-polarized Q channel signal is sampled.

Correspondingly, the signal processing device 602 receives two complex signals, which are an x-polarized signal and a y-polarized signal, respectively. The foregoing S201 to S205 are described by taking one of the x-polarized signal and the y-polarized signal as an example. In actual implementation, the foregoing S201 to S205 are performed for both the x-polarized signal and the y-polarized signal.

It should be noted that the aforementioned coherent receiver 601 may also have other structures, and for example, the aforementioned light detector 6014 may be replaced with other light detectors. The aforementioned two 90° mixers can be replaced by other types of mixers, such as a single mixer.

As mentioned above, the digital signal input by the analog-to-digital converter 6016 to the signal processing device 602 is obtained by converting the entire target signal. Upper sideband component filtering and lower sideband component filtering. FIG. 18 is a schematic structural diagram of another signal processing system 60 provided by an embodiment of the present application. The signal processing apparatus 602 includes: a first digital bandpass filter 6021, which is used for filtering the upper sideband component of the received signal. The second digital bandpass filter 6022 is used to filter the lower sideband component of the received signal. The function of the first digital bandpass filter 6021 in the signal processing device 602 can refer to the function of the first digital bandpass filter in FIG. 7 , and the function of the second digital bandpass filter 6022 in the signal processing device 602 can refer to FIG. Function of the second digital bandpass filter in 7. This is not repeated in this embodiment of the present application.

FIG. 19 is a schematic structural diagram of another signal processing system 60 provided by an embodiment of the present application. The system 60 further includes: an optical splitter 603, the number of coherent receivers 601 is two, the optical splitter 603 is used to receive optical signals from the optical transmission link, and divide the received optical signals into two optical signals, which are respectively input into two In the coherent receiver 601, one of the two coherent receivers 601 is used for filtering the upper sideband component, and the other coherent receiver 601 is used for filtering the lower sideband component. The function of the coherent receiver used for filtering the upper sideband component in the two coherent receivers 601 can refer to the function of the first filter in FIG. 9 , and the function of the coherent receiver used to filter the lower sideband component can refer to FIG. 9 . function of the second filter.

FIG. 20 is a schematic structural diagram of a signal processing system 60 provided by an embodiment of the present application. Wherein, each coherent receiver 601 includes: a local oscillator laser 6011 for generating coherent light and inputting the coherent light into a polarization beam splitter 6012 .

The polarization beam splitter 6012 is used to divide the received optical signal (ie, the optical signal transmitted by the beam splitter 603) into mutually perpendicular first polarized light and second polarized light, and divide the coherent light into mutually perpendicular third polarized light light and fourth polarized light.

Two 90° mixers 6013, wherein one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light frequency.

The photodetector 6014 is used to convert the optical signals output by the two 90° mixers into analog currents. The photodetector 6014 may be a balanced photodetector.

The low-pass filter 6017 is used to filter the analog current to obtain the electrical signal corresponding to the sideband component, for example, the low-pass filter 6017 in the coherent receiver for filtering the upper sideband component is used to filter the analog current to obtain the upper sideband The low-pass filter 6017 in the coherent receiver for filtering the lower sideband component is used to filter the analog current to obtain the electrical signal of the lower sideband component. Optionally, the low-pass filter 6017 is a narrowband filter.

The analog-to-digital converter 6018 is used to convert the electrical signal corresponding to the sideband component into a digital signal.

The aforementioned filter 6015 needs to filter out the complete target signal in the received signal, and its bandwidth is relatively wide. Correspondingly, the analog-to-digital converter 6016 is a high-speed analog-to-digital converter to realize the effective conversion of the electrical signal corresponding to the target signal to the digital signal , that is, the analog-to-digital converter 6016 is an analog-to-digital converter with a high rate and a large processing bandwidth. Since the low-pass filter 6017 only needs to filter out part of the target signal, it is a narrow-band filter, and the analog-to-digital converter 6018 is an analog-to-digital converter with a low rate and can handle a small bandwidth. The speed of the converter 6018 is relatively low relative to the aforementioned analog-to-digital converter 6016, which may be a low-speed analog-to-digital converter. Using a low-speed analog-to-digital converter can save manufacturing costs.

Referring to the aforementioned step B2, if the SNR monitoring method based on the correlation of the upper and lower sidebands of the signal spectrum determines the signal-to-noise ratio, when obtaining the overall signal-to-noise ratio SNR _meas , it is necessary to monitor the total power of the signal and noise in the measurement bandwidth, and if When the signal processing system adopts the structure shown in the aforementioned FIG. 20 , since the two coherent receivers 601 only obtain the sideband components of the target signal and do not obtain the complete target signal, the signal processing device cannot be based on the two coherent receivers. The digital signal output by engine 601 determines the total power of the signal and noise in the measurement bandwidth. An additional power measurement device is required to obtain the total power of the signal and noise in the measurement bandwidth.

FIG. 21 is a schematic structural diagram of another signal processing system 60 provided by an embodiment of the present application. The system further includes a power measuring device 604 for receiving the optical signal from the optical transmission link and measuring the power of the target signal in the optical signal.

FIG. 22 is a schematic structural diagram of still another signal processing system 60 provided by an embodiment of the present application. Wherein, the power measurement device 604 includes:

The local oscillator laser 6011 is used to generate coherent light and input the coherent light to the polarization beam splitter 6012 .

The polarization beam splitter 6012 is used for dividing the received optical signal into mutually perpendicular first polarized light and second polarized light, and dividing the coherent light into mutually perpendicular third polarized light and fourth polarized light.

Two 90° mixers 6013, one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light.

The photodetector 6014 is used to convert the optical signals output by the two 90° mixers into analog currents. For example, the photodetector 6014 can be a balanced photodetector.

The filter 6015 is used for filtering the analog current to obtain the electrical signal corresponding to the target signal, and its function refers to the function of the filter 6015 in the aforementioned FIG. 17 .

The analog-to-digital converter 6018 is used to convert the electrical signal corresponding to the target signal into a digital signal.

The power measurement module 6041 is used to measure the power of the received digital signal.

The functions of the local oscillator laser 6011, the polarization beam splitter 6012, the 90° mixer 6013, the photodetector 6014, the filter 6015, and the analog-to-digital converter 6016 in FIG. 18 to FIG. 22 can refer to the functions of the corresponding modules in FIG. 17 , which is not repeated in this embodiment of the present application.

Wherein, the local oscillator lasers 6011 in the aforementioned FIG. 17 to FIG. 22 can have various center frequencies that can be adjusted. Its center frequency is adjustable, so that it can detect target signals with different center frequencies (also called locating target signals). As shown in FIG. 4 , the local oscillator laser 6011 can download the signal X by adjusting the central wavelength to be the same as the central wavelength of the signal X; the local oscillator laser 6011 can also adjust the central wavelength to be the same as the central wavelength of the signal Y, to download signal Y. In this way, a local oscillator laser 6011 can download signals of different center wavelengths, realize compatible detection of signals of different wavelengths, reduce the manufacturing cost of the signal processing system, and improve the flexibility of the system.

Further, referring to FIG. 9 , the center frequency of the local oscillator laser 6011 can be adjusted to implement frequency offset loading and/or filtering of upper sideband components and lower sideband components in the optical domain.

It is worth noting that the optical signal in the optical transmission link detected in the foregoing embodiment is the optical signal extracted by the optical splitter, the optical splitter is installed in the optical transmission link, and the optical power of the optical signal extracted by the optical splitter is in the optical transmission chain. The proportion of the optical power of the optical signal transmitted in the optical transmission link is small, which does not affect the normal transmission of the optical signal in the optical transmission link. For example, the ratio of the optical power of the optical signal drawn by the optical splitter to the optical power of the optical signal transmitted by the optical transmission link is 1:99.

The signal-to-noise ratio in the embodiments of this application refers to the optical signal-to-noise ratio, the linear signal-to-noise ratio refers to the linear optical signal-to-noise ratio, the nonlinear signal-to-noise ratio refers to the nonlinear optical signal-to-noise ratio, and the center frequency of the local oscillator laser It refers to the center frequency of the coherent light output by the local oscillator laser. The foregoing embodiments are described by taking the position of the filter at zero frequency as an example, but in actual implementation, the position of the filter can be set according to actual needs. When the signal processing apparatus provided in the above embodiment executes the signal processing method, only the division of the above functional modules is used as an example. The structure is divided into different functional modules to complete all or part of the functions described above. In addition, the signal processing apparatus and the signal processing method embodiments provided by the above embodiments belong to the same concept, and the specific implementation process thereof is detailed in the method embodiments, which will not be repeated here.

Those of ordinary skill in the art can understand that all or part of the steps of implementing the above embodiments can be completed by hardware, or can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. The storage medium mentioned may be a read-only memory, a magnetic disk or an optical disk, etc.

The above descriptions are only optional embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection of the present application. within the range.

Claims (28)

1. A signal processing method, characterized in that the method comprises:

   Obtain the first relationship between the linear SNR, the nonlinear SNR, and a relationship parameter in the optical transmission link, where the relationship parameter is used to reflect the correlation between the upper sideband and the lower sideband of the signal in the optical transmission link and frequency offset relationship;

   obtaining the second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link;

   obtaining a target relationship parameter of a target signal received through the optical transmission link;

   obtaining the target signal-to-noise ratio of the target signal;

   Based on the target relationship parameter, the target signal-to-noise ratio, the first relationship and the second relationship, a linear signal-to-noise ratio corresponding to the target signal and a nonlinear signal-to-noise ratio corresponding to the target signal are determined.
2. The method according to claim 1, wherein the first relationship is characterized by a first relationship in which the independent variables are the linear SNR and the nonlinear SNR, and the dependent variable is the relationship parameter , the second relationship is represented by a second relationship in which the independent variable is the linear SNR and the nonlinear SNR, and the dependent variable is the SNR,

   determining the linear signal-to-noise ratio corresponding to the target signal and the nonlinear signal-to-noise ratio corresponding to the target signal based on the target relationship parameter, the target signal-to-noise ratio, the first relationship and the second relationship than, including:

   Substitute the target relational parameters into the first relational expression, substitute the target signal-to-noise ratio into the second relational expression, and obtain the linear signal-to-noise ratio corresponding to the target signal and the The nonlinear signal-to-noise ratio corresponding to the target signal.
3. The method according to claim 1 or 2, wherein the target signal received through the optical transmission link is an optical signal, and the acquiring target relationship parameter of the target signal received through the optical transmission link ,include:

   performing chromatic dispersion compensation on a digital signal, which is converted from the optical signal;

   The relationship parameter of the chromatic dispersion-compensated digital signal is detected to obtain the target relationship parameter.
4. The method according to any one of claims 1 to 3, wherein the acquiring the first relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the relationship parameter in the optical transmission link comprises:

   Determine the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio corresponding to each of the at least three kinds of signals in the optical transmission link, and obtain at least three pairs of linear and nonlinear signal-to-noise ratios, the at least three The linear signal-to-noise ratio and nonlinear signal-to-noise ratio corresponding to the signal are different;

   obtaining a relationship parameter of each of the at least three signals;

   Based on the at least three pairs of linear signal-to-noise ratio and nonlinear signal-to-noise ratio, and the obtained relationship parameters, the first relationship is obtained by fitting.
5. The method according to claim 4, wherein the acquiring the relationship parameter of each of the at least three kinds of signals comprises:

   Apply at least two different frequency offsets to the first signal in the digital domain to obtain at least two kinds of sub-signals, or receive at least two kinds of sub-signals, where the at least two kinds of sub-signals are loaded with different at least two kinds of frequency offsets to the first signal The obtained signal, the first signal is any one of the at least three kinds of signals;

   determining the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals;

   Based on the at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals, a relationship parameter of the first signal is obtained by fitting.
6. The method according to claim 5, wherein the determining the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals comprises:

   For each sub-signal of the at least two sub-signals, obtain an upper sideband component obtained by filtering the sub-signal with an upper sideband component, obtain a lower sideband component obtained by filtering the sub-signal with a lower sideband component, and use the upper sideband component the correlation of the band component and the lower sideband component as the correlation of the upper sideband and the lower sideband of the sub-signal;

   Wherein, the filtering positions of the upper sideband components of the at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering positions of the lower sideband components of the at least two sub-signals are the same, and the filtering bandwidths are the same; The filter bandwidth of the component filter is the same as the filter bandwidth of the lower sideband component filter.
7. The method according to any one of claims 1 to 3, wherein the acquiring the second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link comprises:

   Determine the linear SNR and the nonlinear SNR corresponding to each of the at least three signals in the optical transmission link, and obtain at least three pairs of linear SNR and nonlinear SNR, the at least three signals The corresponding linear SNR and nonlinear SNR are different;

   obtaining a signal-to-noise ratio for each of the at least three signals;

   Based on the at least three pairs of linear signal-to-noise ratio and nonlinear signal-to-noise ratio, and the acquired signal-to-noise ratio, the second relationship is obtained by fitting.
8. The method according to claim 4 or 7, wherein the at least three signals are different in at least one of the following parameters: transmit power, magnification of the corresponding optical amplifier, type of the corresponding optical amplifier, or actively loaded noise .
9. The method according to any one of claims 1 to 8, wherein the relationship parameter is a droop rate, and the droop rate is a correlation between an upper sideband and a lower sideband of a signal in the optical transmission link with frequency increasing rate of descent.
10. A signal processing device, characterized in that the device comprises:

    A first relationship obtaining module, configured to obtain the first relationship between the linear SNR, the nonlinear SNR and a relationship parameter in the optical transmission link, and the relationship parameter is used to reflect the upper edge of the signal in the optical transmission link Band and lower sideband correlation and frequency offset;

    The second relationship obtaining module is used to obtain the second relationship between the linear signal-to-noise ratio, the nonlinear signal-to-noise ratio and the signal-to-noise ratio in the optical transmission link;

    a parameter acquisition module, configured to acquire target relationship parameters of the target signal received through the optical transmission link;

    a signal-to-noise ratio acquisition module for acquiring the target signal-to-noise ratio of the target signal;

    A determination module, configured to determine the linear signal-to-noise ratio corresponding to the target signal and the non-linear signal-to-noise ratio corresponding to the target signal based on the target relationship parameter, the target signal-to-noise ratio, the first relationship and the second relationship Linear signal-to-noise ratio.
11. The apparatus according to claim 10, wherein the first relationship is characterized by a first relationship whose independent variables are the linear signal-to-noise ratio and the nonlinear signal-to-noise ratio, and a dependent variable is the relationship parameter , the second relationship is represented by a second relationship in which the independent variable is the linear SNR and the nonlinear SNR, and the dependent variable is the SNR,

    The determining module is used for:

    Substitute the target relational parameters into the first relational expression, substitute the target signal-to-noise ratio into the second relational expression, and obtain the linear signal-to-noise ratio corresponding to the target signal and the The nonlinear signal-to-noise ratio corresponding to the target signal.
12. The device according to claim 10 or 11, wherein the target signal received through the optical transmission link is an optical signal, and the parameter acquisition module is configured to:

    performing chromatic dispersion compensation on a digital signal, which is converted from the optical signal;

    The relationship parameter of the chromatic dispersion-compensated digital signal is detected to obtain the target relationship parameter.
13. The device according to any one of claims 10 to 12, wherein the first relationship acquisition module comprises:

    A determination submodule, configured to determine the linear SNR and the nonlinear SNR corresponding to each of the at least three signals in the optical transmission link, and obtain at least three pairs of linear SNR and nonlinear SNR , the linear SNR and the nonlinear SNR corresponding to the at least three signals are different;

    an acquisition submodule for acquiring the relationship parameters of each of the at least three types of signals;

    A fitting submodule, configured to obtain the first relationship by fitting based on the at least three pairs of linear signal-to-noise ratios and nonlinear signal-to-noise ratios and the acquired relationship parameters.
14. The device according to claim 13, wherein the acquisition submodule is used for:

    Apply at least two different frequency offsets to the first signal in the digital domain to obtain at least two sub-signals, or receive at least two sub-signals, where the at least two sub-signals are loaded with different at least two frequency offsets to the first signal The obtained signal, the first signal is any one of the at least three kinds of signals;

    determining the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals;

    Based on the at least two frequency offsets and the correlation between the upper sideband and the lower sideband of each of the at least two sub-signals, a relationship parameter of the first signal is obtained by fitting.
15. The device according to claim 14, wherein the acquisition submodule is used for:

    For each of the at least two sub-signals, obtain an upper sideband component obtained by filtering the sub-signal with an upper sideband component, obtain a lower sideband component obtained by filtering the sub-signal with a lower sideband component, and use the upper sideband component the correlation of the band component and the lower sideband component as the correlation of the upper sideband and the lower sideband of the sub-signal;

    Wherein, the filtering positions of the upper sideband components of the at least two sub-signals are the same, and the filtering bandwidths are the same; the filtering positions of the lower sideband components of the at least two sub-signals are the same, and the filtering bandwidths are the same; the upper sideband components of the same sub-signal The filter bandwidth of the component filter is the same as the filter bandwidth of the lower sideband component filter.
16. The device according to any one of claims 10 to 12, wherein the second relationship acquisition module is configured to:

    Determine the linear SNR and the nonlinear SNR corresponding to each of the at least three signals in the optical transmission link, and obtain at least three pairs of linear SNR and nonlinear SNR, the at least three signals The corresponding linear SNR and nonlinear SNR are different;

    obtaining a signal-to-noise ratio for each of the at least three signals;

    Based on the at least three pairs of linear signal-to-noise ratio and nonlinear signal-to-noise ratio, and the acquired signal-to-noise ratio, the second relationship is obtained by fitting.
17. The device according to claim 13 or 16, wherein the at least three signals are different in at least one of the following parameters: transmit power, magnification of the corresponding optical amplifier, type of the corresponding optical amplifier, or actively loaded noise .
18. The apparatus according to any one of claims 10 to 17, wherein the relationship parameter is a droop rate, and the droop rate is a correlation between an upper sideband and a lower sideband of a signal in the optical transmission link as a function of frequency increasing rate of descent.
19. A signal processing system, characterized in that the signal processing system comprises: a coherent receiver and the signal processing device according to any one of claims 10 to 17;

    The coherent receiver is used for receiving an optical signal from an optical transmission link, converting the received optical signal into a digital signal, and sending the converted digital signal to the signal processing device.
20. The system of claim 19, wherein the coherent receiver comprises:

    Local oscillator lasers for generating coherent light;

    A polarization beam splitter, used for dividing the optical signal transmitted by the optical transmission link into mutually perpendicular first polarized light and second polarized light, and dividing the coherent light into mutually perpendicular third polarized light and fourth polarized light ;

    Two 90° mixers, where one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light ;

    a photodetector for converting the optical signals output by the two 90° mixers into analog currents;

    a filter, used for filtering the analog current to obtain an electrical signal corresponding to the target signal;

    The analog-to-digital converter is used to convert the electrical signal corresponding to the target signal into a digital signal.
21. The system according to claim 20, wherein the signal processing device comprises: a first digital bandpass filter for filtering the upper sideband component of the received signal;

    The second digital bandpass filter is used to filter the lower sideband component of the received signal.
22. The system according to claim 19, wherein the system further comprises: an optical splitter, the number of the coherent receivers is 2, the optical splitter is used for receiving the optical signal from the optical transmission link, and combining the received optical signal The optical signal is divided into two optical signals, which are respectively input to the two coherent receivers. One of the two coherent receivers is used to filter the upper sideband component, and the other coherent receiver is used to filter the lower sideband component. filter.
23. The system of claim 22, wherein each of the coherent receivers comprises:

    Local oscillator lasers for generating coherent light;

    A polarization beam splitter, used for dividing the optical signal transmitted by the optical transmission link into mutually perpendicular first polarized light and second polarized light, and dividing the coherent light into mutually perpendicular third polarized light and fourth polarized light ;

    Two 90° mixers, one 90° mixer is used to mix the first polarized light and the third polarized light, and the other 90° mixer is used to mix the second polarized light and the fourth polarized light;

    a photodetector for converting the optical signals output by the two 90° mixers into analog currents;

    a low-pass filter for filtering the analog current to obtain an electrical signal corresponding to the sideband component;

    an analog-to-digital converter for converting the electrical signal of the corresponding sideband component into a digital signal.
24. The system according to claim 22 or 23, characterized in that, the system further comprises: a power measurement device, the power measurement device is configured to receive an optical signal from an optical transmission link, and measure a target signal in the optical signal of power.
25. The system according to any one of claims 20 to 24, wherein the local oscillator laser has a plurality of tunable center frequencies.
26. A computer device, characterized in that the computer device comprises a processor and a memory, the memory stores computer instructions; the processor executes the computer instructions stored in the memory, so that the computer device executes claims 1 to 9 Any of the signal processing methods described.
27. A computer-readable storage medium, characterized in that the computer-readable storage medium stores computer instructions, and the computer instructions instruct the computer device to execute the signal processing method according to any one of claims 1 to 9.
28. A chip, characterized in that the chip includes a programmable logic circuit and/or program instructions, which are used to implement the signal processing method according to any one of claims 1 to 9 when the chip is running.

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