Time delay compensation control method and system for two-way communication of repeater

Abstract

The invention discloses a time delay compensation control method and system for two-way communication of a repeater, particularly relates to the technical field of repeaters, and is used for solving the problem of signal time delay distortion caused by polarization mode dispersion in an optical fiber link. By using polynomial fitting and a frequency domain interpolation algorithm and combining a polarization state time delay spectrum chaos degree index and a phase high-order dynamic variable rate index, the complexity of the model is dynamically adjusted, an accurate nonlinear time delay model is generated, and the defect of nonlinear time delay modeling in a traditional method is overcome; the time delay compensation amount is reversely calculated based on the model and mapped into a phase predistortion parameter, a full-band time delay gradient compensation matrix is formed, and the time delay dispersion effect in an optical fiber link is effectively compensated through phase predistortion; therefore, the flattening correction of the broadband signal time delay is realized, the demodulation performance of the receiving end signal is improved, the communication quality of the repeater in a high-frequency and large-bandwidth scene is ensured, and the high-precision service requirement is met.

Description

Technical Field

[0001] The present invention relates to the technical field of repeater stations, and more specifically, to a delay compensation control method and system for two-way communication of repeaters. Background Art

[0002] In the optical fiber extension system of the repeater station, the long-distance transmission of high-frequency broadband signals relies on the low-loss characteristics of the optical fiber link. However, in actual engineering, due to manufacturing process limitations and external environmental disturbances, the internal polarization characteristics of the optical fiber show non-ideal uniform distribution. During the transmission process, the optical signal undergoes orthogonal polarization state separation due to the polarization mode dispersion effect, and different polarization components propagate at different group velocities, resulting in non-uniform distortion of the signal delay in the frequency domain. This phenomenon is particularly prominent in ultra-wideband multi-carrier signal transmission, and becomes a key physical layer damage that restricts high-frequency communication performance.

[0003] Traditional delay compensation methods only perform global corrections for linear delays or fixed frequency offsets, while the delay distortion caused by polarization mode dispersion is nonlinearly related to the signal frequency, resulting in residual delay gradients in the frequency domain of the compensated signal. This nonlinear delay gradient destroys the orthogonality between subcarriers of multicarrier signals, causing inter-symbol interference and phase noise, which significantly degrades the demodulation performance at the receiving end. Existing technologies lack the ability to dynamically model the delay-frequency nonlinear coupling relationship, and are unable to achieve delay flattening correction for broadband signals, resulting in the communication quality of repeaters in high-frequency and large-bandwidth scenarios being difficult to meet high-precision service requirements.

[0004] In order to solve the above problems, a technical solution is now provided. Summary of the invention

[0005] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a delay compensation control method and system for bidirectional communication of a repeater, which separates orthogonal polarization state signals and extracts frequency domain features; utilizes polynomial fitting and frequency domain interpolation algorithms, combines the polarization state delay spectrum chaos index and the phase high-order dynamic rate index, dynamically adjusts the model complexity, and generates an accurate nonlinear delay model, which overcomes the shortcomings of traditional methods in modeling nonlinear delays; based on the model, the delay compensation amount is reversely calculated and mapped to a phase predistortion parameter, forming a full-band delay gradient compensation matrix, and effectively compensates for the delay dispersion effect in the optical fiber link through phase predistortion; thereby achieving flattening correction of broadband signal delay, improving the demodulation performance of the receiving end signal, ensuring the communication quality of the repeater in high-frequency and large-bandwidth scenarios, and meeting high-precision business requirements, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A delay compensation control method for two-way communication of a repeater comprises the following steps:

[0008] S1. Separate the orthogonal polarization signal components in the optical fiber link through the polarization diversity receiving module, extract the frequency domain amplitude and phase characteristics of each component, and construct the original data set;

[0009] S2. Based on the original data set, the model complexity is dynamically adjusted according to the nonlinear characteristics of the time delay information and phase information using polynomial fitting and frequency domain interpolation algorithms to generate a nonlinear function model of the time delay varying with frequency under each polarization state;

[0010] S3. According to the nonlinear function model, the delay compensation amount of each frequency point is reversely calculated and mapped into a frequency domain phase pre-distortion parameter to form a delay gradient compensation matrix covering the entire frequency band;

[0011] S4. Load the delay gradient compensation matrix into the digital pre-equalization module, and apply a phase pre-distortion in the opposite direction of the nonlinear delay gradient to the baseband signal at the transmitting end to compensate for the delay dispersion effect of the signal at the receiving end.

[0012] In a preferred embodiment, step S1 includes the following contents:

[0013] At the remote unit receiving end of the repeater, the optical signal transmitted by the optical fiber link is decomposed into horizontal polarization state signal and vertical polarization state signal by using polarization controller and polarization beam splitter. The separated horizontal polarization state signal and vertical polarization state signal are transformed into frequency domain representation by fast Fourier transform and the amplitude and phase information is extracted. Based on the phase information, the group delay of the horizontal polarization state signal and the vertical polarization state signal is calculated by using finite difference method. The frequency, polarization state mark, amplitude, phase and group delay are integrated into the original data set.

[0014] In a preferred embodiment, step S2 includes the following contents:

[0015] S2-1, extracting the time delay and phase of each polarization state from the original data set; wherein the time delay information includes the polarization state time delay spectrum chaos index, and the phase information includes the phase high-order dynamic rate index.

[0016] In a preferred embodiment, S2-2, fast Fourier transform is performed on the delay data of the horizontal polarization state and the vertical polarization state respectively to obtain the spectrum representation of the delay in the frequency domain; based on this spectrum, the power spectrum density of each frequency point is calculated, and the sum of the power spectrum densities of all frequency points is normalized and converted into a probability density distribution; then, the Shannon entropy of the probability density distribution is calculated to quantify the randomness of the delay spectrum; at the same time, the approximate value of the Lyapunov exponent of the delay data on the frequency axis is calculated; finally, the exponential function value of the Shannon entropy and the Lyapunov index is multiplied to obtain the chaos index of the polarization state delay spectrum, and its numerical range is normalized and adjusted to between 0 and 1.

[0017] In a preferred embodiment, S2-3, for the phase data of the horizontal polarization state and the vertical polarization state, the first to fourth order derivatives of the phase are calculated using the five-point difference method; the first order derivative reflects the rate of change of the phase with frequency, the second order derivative reflects the acceleration of the rate of change, the third order derivative reflects the rate of change of acceleration, and the fourth order derivative reflects higher order dynamic characteristics; each order derivative is Fourier transformed to obtain its spectrum representation, and the energy of the spectrum is calculated, and the energy is obtained by summing the squares of the amplitudes of each frequency point in the spectrum; then, the ratio of the sum of the energies of the third and fourth order derivatives to the sum of the energies of the first and second order derivatives is calculated to evaluate the relative intensity of high order dynamic changes; at the same time, the peak frequency in the third order derivative spectrum is found, and a dynamic weighting factor is calculated based on this, the energy ratio is multiplied by the dynamic weighting factor to obtain the phase high order dynamic rate index, and its numerical range is normalized and adjusted to between 0 and 1.

[0018] In a preferred embodiment, S2-4, the polarization state delay spectrum chaos index and the phase high-order dynamic rate index of the horizontal polarization state and the vertical polarization state are averaged respectively to obtain two comprehensive indicators, and the two comprehensive indicators are weighted averaged using a preset weight value to obtain the delay phase nonlinear complexity coefficient;

[0019] S2-5, compare the delay phase nonlinear complexity coefficient with the preset threshold. If the delay phase nonlinear complexity coefficient is greater than the preset threshold, select a multi-order polynomial model; if the delay phase nonlinear complexity coefficient is less than or equal to the preset threshold, select a low-order polynomial model.

[0020] In a preferred embodiment, S2-6, the time delay data of the horizontal polarization state and the vertical polarization state are subjected to polynomial fitting using weighted least squares method based on the dynamically selected model order to generate a nonlinear function model of the time delay varying with frequency.

[0021] In a preferred embodiment, step S3 includes the following contents:

[0022] Based on the nonlinear function model of horizontal polarization state and vertical polarization state, the target delay is first calculated and the arithmetic mean of the two is taken; then, for each polarization state and each frequency point, the delay compensation amount is calculated, that is, the difference between the target delay and the delay of the corresponding polarization state at the corresponding frequency point; then, the trapezoidal numerical integration method is used to convert the delay compensation amount into a phase adjustment amount; finally, the phase adjustment amounts of the horizontal polarization state and the vertical polarization state at all frequency points are integrated into a delay gradient compensation matrix.

[0023] In a preferred embodiment, step S4 includes the following contents:

[0024] The delay gradient compensation matrix is ​​loaded in the digital pre-equalization module at the transmitter end of the repeater station. The delay gradient compensation matrix contains the phase adjustment amount of the horizontal polarization state and the vertical polarization state at each frequency point; the baseband signal is converted into the frequency domain form through fast Fourier transform and decomposed into horizontal polarization state and vertical polarization state components; for the frequency domain signal component of each polarization state, a phase pre-distortion in the opposite direction to the delay gradient is applied at each frequency point; the pre-distorted frequency domain signal is subjected to inverse fast Fourier transform to obtain a time domain pre-distortion signal and polarization multiplexing is performed; the multiplexed signal is modulated into an optical signal and transmitted through an optical fiber link to compensate for the delay dispersion effect.

[0025] A time delay compensation control system for two-way communication of a repeater station, comprising: a signal separation module, a model generation module, a compensation calculation module and a pre-distortion compensation module;

[0026] Signal separation module: Separate the orthogonal polarization signal components in the optical fiber link through the polarization diversity receiving module, extract the frequency domain amplitude and phase characteristics, and construct the original data set;

[0027] Model generation module: Based on the original data set, the model complexity is dynamically adjusted according to the nonlinear characteristics of time delay and phase using polynomial fitting and frequency domain interpolation algorithms to generate a nonlinear function model of time delay varying with frequency under each polarization state;

[0028] Compensation calculation module: According to the nonlinear function model, the delay compensation amount of each frequency point is reversely calculated and mapped into the frequency domain phase pre-distortion parameter to form a delay gradient compensation matrix covering the entire frequency band;

[0029] Pre-distortion compensation module: The delay gradient compensation matrix is ​​loaded into the digital pre-equalization module, and a phase pre-distortion in the opposite direction of the nonlinear delay gradient is applied to the baseband signal at the transmitting end to compensate for the delay dispersion effect of the signal at the receiving end.

[0030] The technical effects and advantages of the delay compensation control method and system for two-way communication of a repeater of the present invention are as follows:

[0031] Through the polarization diversity receiving module, the orthogonal polarization state signals are accurately separated and the frequency domain features are extracted to construct a high-precision delay data set; on this basis, the polynomial fitting and frequency domain interpolation algorithms are used, combined with the polarization state delay spectrum chaos index and the phase high-order dynamic rate index, the model complexity is dynamically adjusted to generate an accurate nonlinear delay model, overcoming the shortcomings of traditional methods in modeling nonlinear delays; based on the model, the delay compensation amount is reversely calculated and mapped to the phase pre-distortion parameter to form a full-band delay gradient compensation matrix; the matrix is ​​applied to the digital pre-equalization module, and the delay dispersion effect in the optical fiber link is effectively compensated through phase pre-distortion; thus, the flattening correction of the broadband signal delay is realized, which significantly reduces the inter-symbol interference and phase noise, improves the demodulation performance of the receiving end signal, ensures the communication quality of the repeater in high-frequency and large-bandwidth scenarios, and meets the high-precision business needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of a method for controlling delay compensation in two-way communication of a repeater.

[0033] Figure 2 The present invention is a schematic diagram of the structure of a delay compensation control system for two-way communication of a repeater. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Embodiment 1: Figure 1 The invention provides a delay compensation control method for a repeater bidirectional communication, comprising:

[0036] S1. The orthogonal polarization state signal components in the optical fiber link are separated by a polarization diversity receiving module, and the frequency domain amplitude and phase characteristics of each component are extracted to construct the original data set.

[0037] S2. Based on the original data set, polynomial fitting and frequency domain interpolation algorithms are used to dynamically adjust the model complexity according to the nonlinear characteristics of the time delay information and phase information, and a nonlinear function model of the time delay varying with frequency under each polarization state is generated.

[0038] S3. According to the nonlinear function model, the delay compensation amount of each frequency point is reversely calculated and mapped into the frequency domain phase pre-distortion parameter to form a delay gradient compensation matrix covering the entire frequency band.

[0039] S4. Load the delay gradient compensation matrix into the digital pre-equalization module, and apply a phase pre-distortion in the opposite direction of the nonlinear delay gradient to the baseband signal at the transmitting end to compensate for the delay dispersion effect of the signal at the receiving end.

[0040] In the optical fiber extension system of the repeater station, the optical signal is transmitted to the remote unit through the optical fiber link to achieve signal coverage. Due to the polarization mode dispersion (PMD) effect in the optical fiber, the optical signal will produce delay distortion due to the difference in polarization state during transmission. Especially in high-bandwidth signal transmission, the frequency domain non-uniformity of this delay significantly affects the communication quality. The goal of step S1 is to separate the orthogonal polarization state components of the optical signal received from the optical fiber link, extract the frequency domain features and calculate the delay information, generate the original data set containing frequency, polarization state and delay, and provide accurate basic data for the construction of the nonlinear model in step S2.

[0041] Step S1 includes the following contents:

[0042] S1-1, separation of orthogonal polarization signal components: A polarization diversity receiving module is deployed at the remote unit receiving end of the repeater. This module decomposes the optical signal transmitted from the optical fiber link into two mutually orthogonal polarization components through a polarization controller and a polarization beam splitter: one is a horizontal polarization signal and the other is a vertical polarization signal. The polarization controller monitors the polarization state of the input optical signal in real time and dynamically adjusts the polarization direction to ensure that the separated horizontal polarization signal and vertical polarization signal maintain an orthogonal relationship, avoiding confusion of signal characteristics due to overlapping polarization states.

[0043] S1-2, extraction of frequency domain amplitude and phase features: The separated horizontal polarization state signal and vertical polarization state signal are processed by fast Fourier transform respectively, and converted from time domain to frequency domain representation. Through this conversion, the complex form of the horizontal polarization state signal and the vertical polarization state signal in the frequency domain is obtained. Then, the amplitude and phase information is extracted from the frequency domain signal: for the horizontal polarization state signal, its amplitude and phase at each frequency point are extracted; for the vertical polarization state signal, its amplitude and phase at each frequency point are also extracted. These amplitude and phase information reflect the intensity distribution and phase distribution of the two polarization state signals in the frequency domain, providing the necessary data basis for subsequent processing.

[0044] S1-3, calculation of group delay characteristics: use the extracted phase information to calculate the group delay of the horizontal polarization state signal and the vertical polarization state signal. Group delay refers to the characteristic of phase changing with frequency. When calculating, for the horizontal polarization state signal, take the negative value of its phase change rate with frequency and divide it by a constant (2π); for the vertical polarization state signal, the calculation method is the same. To ensure the accuracy of the calculation, the finite difference method is used to approximate the rate of change of phase with frequency: by calculating the difference in phase between adjacent frequency points, and then dividing it by the step size between the frequencies, the phase change rate is obtained, and then the group delay is obtained. This method accurately describes the characteristics of the delay changing with frequency by calculating the phase difference between adjacent frequency points.

[0045] S1-4, construction of the original data set: the extracted amplitude, phase and calculated group delay characteristics are integrated into an original data set. The data set includes the following information for each frequency point: frequency value, polarization state mark (indicating whether it is a horizontal polarization state signal or a vertical polarization state signal), the amplitude, phase and group delay of the polarization state signal at the frequency point. These data are stored in a structured form to ensure that each data point can be accurately traced and referenced, providing complete and consistent data support for model construction in subsequent processing.

[0046] Step S1 decomposes the optical signal into horizontal polarization state signal and vertical polarization state signal through the polarization diversity receiving module, extracts its frequency domain amplitude and phase characteristics, and calculates the group delay based on the phase information, and finally constructs an original data set containing frequency, polarization state mark, amplitude, phase and group delay. This data set provides an accurate and comprehensive data foundation for the subsequent model construction based on delay and phase characteristics.

[0047] Step S1 has separated the orthogonal polarization state signal components from the optical fiber link through the polarization diversity receiving module, and extracted the frequency domain amplitude and phase characteristics of each component to construct the original data set. Based on this data set, step S2 aims to use the algorithm to generate a nonlinear function model of the delay variation with frequency under each polarization state, and quantify the gradient distribution law of the delay, providing an accurate basis for the delay compensation of step S3. This processing logic breaks through the limitations of the traditional fixed model in terms of novelty, ensuring that the delay characteristics of signal transmission in the repeater system can be accurately modeled.

[0048] Step S2 includes the following contents:

[0049] S2-1, from the original dataset Extract the time delay τ of each polarization state p from p (f) and phase φ p (f), where f represents frequency, p = x represents horizontal polarization state, and p = y represents vertical polarization state. p(f) A moving average filter was applied for smoothing with a filter window width of 5 frequency points to reduce the impact of noise on subsequent analysis.

[0050] The time delay information includes the chaotic index of polarization state time delay spectrum, and the phase information includes the phase high-order dynamic rate index.

[0051] S2-2, perform fast Fourier transform on the delay data of the horizontal polarization state and the vertical polarization state respectively to obtain the spectrum representation of the delay in the frequency domain. Based on this spectrum, calculate the power spectrum density of each frequency point, and normalize the sum of the power spectrum densities of all frequency points to convert it into a probability density distribution. Next, calculate the Shannon entropy of the probability density distribution to quantify the randomness of the delay spectrum. Shannon entropy is obtained by taking the logarithm of each probability value and multiplying it by itself, then summing all the results and taking the inverse. At the same time, calculate the approximate value of the Lyapunov exponent of the delay data on the frequency axis. The specific method is to calculate the ratio of the delay difference between adjacent frequency points, take the logarithm of these ratios and average them to reflect the chaotic characteristics of the delay change. Finally, multiply the exponential function values ​​of Shannon entropy and Lyapunov index to obtain the chaotic index of the polarization state delay spectrum, and normalize its numerical range to between 0 and 1. The acquisition logic of the chaotic index of the polarization state delay spectrum is:

[0052] The time delay function τ for each polarization state p p (f) Perform fast Fourier transform (FFT) to obtain the spectrum T p (ω)=FFT(τ p (f)), where ω is the transform domain frequency. Calculate the power spectral density P p (ω)=|T p (ω)| 2 , and normalized to a probability density distribution Calculate the Shannon entropy of the spectrum Used to quantify the randomness of the delay spectrum. Calculate the Lyapunov exponent approximation of the delay function Where N is the number of frequency sampling points, reflecting the chaotic characteristics of delay changes, and k is a discrete counter used for iteration in the summation process. p =S p ·exp(λ p ), and normalized to the interval [0,1]: PDSCI min and PDSCI max Determined from historical data.

[0053] The polarization state delay spectrum chaos index is used to quantify the nonlinear fluctuation and chaos degree of the delay in the frequency domain, reflecting the complexity and unpredictability of the delay with frequency. When the index value is large, it indicates that the spectrum distribution of the delay is more irregular, the delay changes with frequency more drastically and is difficult to predict, and it shows a strong chaotic characteristic; when the index value is small, it means that the delay changes with frequency more smoothly, the distribution is more regular, and it has a higher predictability.

[0054] S2-3, for the phase data of the horizontal polarization state and the vertical polarization state, the five-point difference method is used to calculate the first to fourth order derivatives of the phase. The first-order derivative reflects the rate of change of the phase with frequency, the second-order derivative reflects the acceleration of the rate of change, the third-order derivative reflects the rate of change of acceleration, and the fourth-order derivative reflects higher-order dynamic characteristics. Perform Fourier transform on each derivative to obtain its spectrum representation, and calculate the energy of the spectrum. The energy is obtained by summing the squares of the amplitudes of each frequency point in the spectrum. Next, calculate the ratio of the sum of the energies of the third-order and fourth-order derivatives to the sum of the energies of the first-order and second-order derivatives to evaluate the relative intensity of high-order dynamic changes. At the same time, find the peak frequency in the third-order derivative spectrum, and based on this, calculate a dynamic weighting factor that increases with the increase of the peak frequency. Multiply the energy ratio by the dynamic weighting factor to obtain the phase high-order dynamic variability index, and normalize its numerical range to between 0 and 1. The acquisition logic of the phase high-order dynamic variability index is:

[0055] The phase function φ for each polarization state p p (f) Calculate the first to fourth order derivatives: φ′ p (f),φ″ p (f), φ″′ p (f),φ″″ p (f) The five-point difference method is used for numerical differentiation. Fourier transform is performed on each derivative to obtain the spectrum Where n = 1, 2, 3, 4. Calculate the frequency domain energy of each order Calculate the ratio of high-order to low-order energy where ∈ = 10 -6 To avoid small positive numbers with zero denominators. Determine the peak frequency of the third derivative spectrum And calculate the dynamic weighting factor where ω max It is the maximum frequency of the spectrum. Comprehensive calculation of PHDVI: PHDVI p =R p ·W p , and normalized to the interval [0,1]: Where k1=1 is the adjustment constant.

[0056] The phase high-order dynamic rate index is used to evaluate the high-order nonlinear dynamic changes of the phase in the frequency domain, reflecting the intensity and complex dynamic characteristics of the phase change with frequency. When the index value is large, it means that the high-order derivative of the phase changes more drastically, the nonlinear fluctuation of the phase with frequency is enhanced, and the dynamic change shows a higher complexity; when the index value is small, it means that the phase changes more slowly with frequency, the nonlinear characteristics are weakened, and the dynamic change tends to be simple.

[0057] S2-4, average the polarization state delay spectrum chaos index and phase high-order dynamic variability index of the horizontal polarization state and the vertical polarization state, respectively, to obtain two comprehensive indicators. Use the preset weight values, for example, the weight of the polarization state delay spectrum chaos index is 0.6, and the weight of the phase high-order dynamic variability index is 0.4, and take a weighted average of the two comprehensive indicators. The specific calculation method is to multiply the average value of the polarization state delay spectrum chaos index by 0.6, and the average value of the phase high-order dynamic variability index by 0.4, and then add the two results to obtain the delay phase nonlinear complexity coefficient. This coefficient reflects the overall complexity of the delay and phase nonlinear characteristics.

[0058] S2-5, set a preset threshold, and compare the delay phase nonlinear complexity coefficient with the preset threshold. If the delay phase nonlinear complexity coefficient is greater than the preset threshold, a multi-order polynomial model, such as the seventh order, is selected; if the delay phase nonlinear complexity coefficient is less than or equal to the preset threshold, a low-order polynomial model, such as the third order, is selected. This dynamic selection mechanism ensures that the complexity of the selected model matches the degree of nonlinearity of the delay and phase.

[0059] The third-order polynomial (i.e., cubic model) is the lowest-order model that can effectively describe nonlinear trends. It can not only fit linear changes, but also capture the concavity and convexity (i.e., mild nonlinear characteristics) in the delay curve, which is very suitable for scenarios where the delay changes slowly with frequency. The seventh-order polynomial can capture the complex characteristics of the delay that changes dramatically with frequency and is highly nonlinear. In some scenarios with a high degree of nonlinearity, low-order models (such as third-order) may not be able to fully fit, while the seventh-order model can significantly improve the accuracy.

[0060] S2-6, for the delay data of the horizontal polarization state and the vertical polarization state, based on the dynamically selected model order, the weighted least squares method is used to perform polynomial fitting to generate a nonlinear function model of the delay varying with frequency. During the fitting process, the weight is determined according to the local change rate of the delay data. The specific method is to calculate the change rate of the delay near each frequency point. The greater the change rate, the lower the weight given to the point, so as to reduce the impact of outliers on the fitting results. Through this method, a nonlinear function model describing the delay varying with frequency is obtained.

[0061] S2-7, for the fitted nonlinear function model, use the cubic spline interpolation method to insert additional sampling points on the frequency axis. Specifically, between the original frequency points, new sampling points are calculated based on cubic spline interpolation, so that the total number of sampling points is increased to twice the original number. This process improves the resolution and accuracy of the nonlinear function model in the frequency domain.

[0062] S2-8, for the nonlinear function model after interpolation optimization, calculate its delay gradient at each frequency point, that is, the rate of change of delay with frequency. The specific method is to divide the delay difference between adjacent frequency points by the corresponding frequency interval to obtain the gradient value of each frequency point. Then, calculate the mean and peak value of all delay gradients, and analyze the overall change trend of delay gradients in the frequency domain, and record these results as input data for subsequent steps.

[0063] Based on the original data set generated in step S1, step S2 realizes the dynamic adjustment of model complexity by calculating the chaotic index of polarization state delay spectrum and the high-order dynamic rate index of phase, and combines the nonlinear complexity coefficient of delay phase, and generates a nonlinear function model of delay variation with frequency under each polarization state. At the same time, by quantifying the distribution law of delay gradient, it provides an accurate theoretical basis for the reverse calculation of delay compensation in step S3. This process improves the model accuracy through chaos and high-order dynamic analysis in terms of novelty, ensuring the accurate characterization of delay characteristics in the optical fiber extension system of the repeater station.

[0064] The goal of step S3 is to reversely calculate the delay compensation amount of each frequency point based on the nonlinear function model output by step S2, and map it to the frequency domain phase pre-distortion parameter, and finally form a delay gradient compensation matrix covering the entire frequency band, providing an accurate compensation basis for the digital pre-equalization in step S4. In the repeater scenario, the delay dispersion effect of the optical fiber link will cause the signal transmission quality to deteriorate. The processing of step S3 ensures the delay consistency of the signal at the receiving end and improves the communication performance by accurately compensating the delay gradient.

[0065] Step S3 includes the following contents:

[0066] S3-1, first, based on the nonlinear function model of the horizontal polarization state and the vertical polarization state, calculate the target delay. The target delay refers to the arithmetic mean of the horizontal polarization state delay and the vertical polarization state delay. The specific calculation method is that, for each frequency point, add the delay of the horizontal polarization state at the frequency point and the delay of the vertical polarization state at the frequency point, and then divide the result by 2 to obtain the target delay at the frequency point. Next, for each polarization state and each frequency point, calculate the delay compensation amount. The delay compensation amount refers to the difference between the target delay and the delay of the polarization state at the frequency point, specifically, the target delay minus the delay of the polarization state at the frequency point. A positive value of the delay compensation amount indicates that the delay at the frequency point needs to be increased, and a negative value indicates that the delay at the frequency point needs to be reduced.

[0067] S3-2, in order to convert the delay compensation amount into the phase adjustment amount, an integration-based processing method is adopted. The specific process is to calculate the phase adjustment amount by integrating the delay compensation amount within the frequency range. The starting point of the integration is set to the reference frequency, and the lowest frequency of the entire frequency band is usually selected. The integration process uses the trapezoidal numerical integration method for approximate calculation: first, the frequency axis is divided into multiple small segments. In each small segment, it is assumed that the delay compensation amount changes linearly, and the average value of the delay compensation amount in the small segment is calculated. Then, this average value is multiplied by the frequency width of the small segment to obtain the contribution of the small segment to the phase change. The phase change contributions of all small segments are added up in sequence to obtain the phase adjustment amount at the frequency point. This method ensures that the calculation result of the phase adjustment amount is both accurate and smooth.

[0068] S3-3, for the horizontal polarization state and the vertical polarization state, a phase adjustment amount is generated at each frequency point. These phase adjustment amounts will be used to apply phase pre-distortion to the baseband signal at the signal transmitting end to offset the phase distortion caused by the delay dispersion effect in the optical fiber link. Through this processing method, it can ensure that the signal is restored to the ideal phase state at the receiving end, avoiding the degradation of signal quality due to delay differences.

[0069] S3-4, integrates the phase adjustment of the horizontal polarization state and the vertical polarization state at all frequency points into a matrix. This matrix contains two rows, the first row corresponds to the phase adjustment of the horizontal polarization state, and the second row corresponds to the phase adjustment of the vertical polarization state; the number of columns in the matrix is ​​the same as the total number of frequency points, and each column corresponds to the phase adjustment of one frequency point. This matrix completely covers the delay gradient compensation information of the entire frequency band, providing an accurate phase adjustment basis for the subsequent digital pre-equalization module, ensuring that the compensation for each polarization state and each frequency point is accurate.

[0070] Step S3 is based on the nonlinear function model output by step S2, by calculating the target delay and delay compensation, and mapping the delay compensation to the frequency domain phase pre-distortion parameter using the trapezoidal numerical integration method, and finally generating a delay gradient compensation matrix covering the entire frequency band. In the optical fiber extension system of the repeater station, this matrix provides an accurate phase adjustment basis for the digital pre-equalization module of step S4, effectively compensating for the delay dispersion effect in the optical fiber link, and ensuring the delay consistency of the receiving end signal and the improvement of communication quality.

[0071] Step S3 reversely calculates the delay compensation amount of each frequency point according to this model, maps it into frequency domain phase predistortion parameters, and forms a delay gradient compensation matrix covering the entire frequency band. Step S4 aims to apply this matrix to the digital pre-equalization module at the transmitting end, compensate the delay dispersion effect in the optical fiber link through phase predistortion, ensure the delay consistency of the remote receiving signal of the repeater, and improve the communication quality.

[0072] Step S4 includes the following contents:

[0073] S4-1, loading the delay gradient compensation matrix: In the digital pre-equalization module at the transmitter of the repeater, the delay gradient compensation matrix generated in the previous stage is first received and stored. This matrix contains the phase adjustment amounts of the horizontal polarization state and the vertical polarization state at each frequency point. These phase adjustment amounts are pre-calculated and used for subsequent signal processing. After storage, the system can call these phase adjustment amounts in real time when processing the baseband signal to ensure accurate phase pre-distortion processing of the signal.

[0074] S4-2, frequency domain representation of baseband signal: The baseband signal at the transmitting end initially exists in the form of time domain. In order to facilitate the subsequent phase adjustment operation, the system converts the baseband signal from the time domain to the frequency domain through the fast Fourier transform technology to generate the corresponding frequency domain signal. Then, according to the transmission characteristics of the optical fiber link, the frequency domain signal is decomposed into horizontal polarization state components and vertical polarization state components. In order to maintain a balanced distribution of signal energy between the two polarization states, the coefficients allocated to each polarization state component are usually set to a fixed value, specifically, equal distribution.

[0075] S4-3, apply phase predistortion: For the frequency domain signals of the horizontal polarization state and the vertical polarization state after decomposition, the system performs phase adjustment operations at each frequency point respectively. Specifically, the phase adjustment amount corresponding to the current frequency point is extracted from the delay gradient compensation matrix. These phase adjustment amounts are used to guide the phase predistortion processing. During processing, the system adjusts the phase of the frequency domain signal through phase rotation technology, that is, multiplying the frequency domain signal of each frequency point by a complex phase rotation factor. The phase angle of this rotation factor is completely consistent with the phase adjustment amount recorded in the delay gradient compensation matrix, thereby achieving accurate pre-adjustment of the signal phase.

[0076] S4-4, frequency domain signal inverse transformation: After completing the phase predistortion, the frequency domain signals of the horizontal polarization state and the vertical polarization state need to be converted back to the time domain form. The system performs inverse fast Fourier transform on the predistorted frequency domain signals of these two polarization states to generate corresponding time domain predistortion signals. Subsequently, the time domain predistortion signal of the horizontal polarization state and the time domain predistortion signal of the vertical polarization state are polarization multiplexed to synthesize a complete transmission signal. This synthesized transmission signal is ready for subsequent optical modulation.

[0077] S4-5, modulation and transmission of transmission signals: The synthesized transmission signal is input into the optical modulator at the transmitter end of the repeater and converted into an optical signal through the optical modulation process. Subsequently, this optical signal is transmitted to the remote unit through the optical fiber link. During the optical fiber transmission process, the optical signal will be affected by the delay dispersion effect. However, since the transmitter has pre-applied phase pre-distortion, this pre-distortion and the delay dispersion effect in the optical fiber link offset each other, thereby ensuring that the signal received by the remote unit remains consistent in delay, ultimately improving the overall quality of the communication system.

[0078] Step S4 loads the delay gradient compensation matrix generated in step S3 into the digital pre-equalization module, applies phase pre-distortion in the opposite direction of the nonlinear delay gradient to the baseband signal at the transmitter of the repeater, and achieves accurate compensation for the delay dispersion effect of the optical fiber link. This process ensures the delay consistency of the far-end received signal and improves the communication quality of the optical fiber extension system of the repeater. The phase pre-distortion technology lies in its adaptive adjustment capability based on the nonlinear delay model, which can optimize the compensation effect for different optical fiber link conditions, thereby enhancing the system robustness and performance stability.

[0079] Embodiment 2: Figure 2 The invention provides a time delay compensation control system for two-way communication of a repeater, comprising: a signal separation module, a model generation module, a compensation calculation module and a pre-distortion compensation module;

[0080] Signal separation module: The orthogonal polarization state signal components in the optical fiber link are separated through the polarization diversity receiving module, the frequency domain amplitude and phase characteristics are extracted, and the original data set is constructed.

[0081] Model generation module: Based on the original data set, the model complexity is dynamically adjusted according to the nonlinear characteristics of time delay and phase using polynomial fitting and frequency domain interpolation algorithms to generate a nonlinear function model of the time delay varying with frequency under each polarization state.

[0082] Compensation calculation module: According to the nonlinear function model, the delay compensation amount of each frequency point is reversely calculated and mapped into the frequency domain phase pre-distortion parameter to form a delay gradient compensation matrix covering the entire frequency band.

[0083] Pre-distortion compensation module: The delay gradient compensation matrix is ​​loaded into the digital pre-equalization module, and a phase pre-distortion in the opposite direction of the nonlinear delay gradient is applied to the baseband signal at the transmitting end to compensate for the delay dispersion effect of the signal at the receiving end.

[0084] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0085] It should be noted that the system of the present invention can be deployed on the device itself to realize embedded applications, and can also be run on a PC or other terminal with a user interface, thereby meeting a variety of hardware environments and usage requirements.

[0086] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

[0087] It should be noted that, in this article, if there are relational terms such as first and second, etc., they are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0088] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A delay compensation control method for two-way communication of a repeater, characterized in that: Includes steps: S1. Separate the orthogonal polarization signal components in the optical fiber link through the polarization diversity receiving module, extract the frequency domain amplitude and phase characteristics of each component, and construct the original data set; S2. Based on the original data set, the model complexity is dynamically adjusted according to the nonlinear characteristics of the delay information and phase information using polynomial fitting and frequency domain interpolation algorithms to generate a nonlinear function model of the delay varying with frequency under each polarization state; S3. According to the nonlinear function model, the delay compensation amount of each frequency point is reversely calculated and mapped into a frequency domain phase pre-distortion parameter to form a delay gradient compensation matrix covering the entire frequency band; S4. Load the delay gradient compensation matrix into the digital pre-equalization module, and apply a phase pre-distortion in the opposite direction of the nonlinear delay gradient to the baseband signal at the transmitting end to compensate for the delay dispersion effect of the signal at the receiving end.

2. The delay compensation control method for two-way communication of a repeater according to claim 1, characterized in that: Step S1 includes the following contents: At the remote unit receiving end of the repeater, the optical signal transmitted by the optical fiber link is decomposed into horizontal polarization state signal and vertical polarization state signal by using polarization controller and polarization beam splitter. The separated horizontal polarization state signal and vertical polarization state signal are transformed into frequency domain representation by fast Fourier transform and the amplitude and phase information is extracted. Based on the phase information, the group delay of the horizontal polarization state signal and the vertical polarization state signal is calculated by using finite difference method. The frequency, polarization state mark, amplitude, phase and group delay are integrated into the original data set.

3. The delay compensation control method for two-way communication of a repeater according to claim 2, characterized in that: Step S2 includes the following contents: S2-1, extracting the time delay and phase of each polarization state from the original data set; wherein the time delay information includes the polarization state time delay spectrum chaos index, and the phase information includes the phase high-order dynamic rate index.

4. The delay compensation control method for two-way communication of a repeater according to claim 3, characterized in that: S2-2, perform fast Fourier transform on the delay data of the horizontal polarization state and the vertical polarization state respectively to obtain the spectrum representation of the delay in the frequency domain; based on this spectrum, calculate the power spectrum density of each frequency point, and normalize the sum of the power spectrum densities of all frequency points to convert it into a probability density distribution; then, calculate the Shannon entropy of the probability density distribution to quantify the randomness of the delay spectrum; at the same time, calculate the approximate value of the Lyapunov exponent of the delay data on the frequency axis; finally, multiply the exponential function value of the Shannon entropy and the Lyapunov index to obtain the chaos index of the polarization state delay spectrum, and normalize its numerical range to between 0 and 1.

5. The delay compensation control method for two-way communication of a repeater according to claim 4, characterized in that: S2-3, for the phase data of the horizontal polarization state and the vertical polarization state, the five-point difference method is used to calculate the first to fourth order derivatives of the phase; the first order derivative reflects the rate of change of the phase with frequency, the second order derivative reflects the acceleration of the rate of change, the third order derivative reflects the rate of change of acceleration, and the fourth order derivative reflects higher order dynamic characteristics; each order derivative is Fourier transformed to obtain its spectrum representation, and the energy of the spectrum is calculated. The energy is obtained by summing the squares of the amplitudes of each frequency point in the spectrum; then, the ratio of the sum of the energies of the third and fourth order derivatives to the sum of the energies of the first and second order derivatives is calculated to evaluate the relative intensity of high order dynamic changes; at the same time, the peak frequency in the third order derivative spectrum is found, and a dynamic weighting factor is calculated based on this, the energy ratio is multiplied by the dynamic weighting factor to obtain the phase high order dynamic rate index, and its numerical range is normalized and adjusted to between 0 and 1.

6. The delay compensation control method for two-way communication of a repeater according to claim 5, characterized in that: S2-4, respectively averaging the polarization state delay spectrum chaos index and the phase high-order dynamic rate index of the horizontal polarization state and the vertical polarization state to obtain two comprehensive indicators, and using a preset weight value to perform weighted averaging on the two comprehensive indicators to obtain the delay phase nonlinear complexity coefficient; S2-5, comparing the delay phase nonlinear complexity coefficient with a preset threshold, and if the delay phase nonlinear complexity coefficient is greater than the preset threshold, selecting a multi-order polynomial model; If the delay phase nonlinear complexity coefficient is less than or equal to a preset threshold, a low-order polynomial model is selected.

7. The delay compensation control method for two-way communication of a repeater according to claim 6, characterized in that: S2-6, for the time delay data of the horizontal polarization state and the vertical polarization state, based on the dynamically selected model order, a weighted least squares method is used to perform polynomial fitting to generate a nonlinear function model of the time delay varying with frequency.

8. The delay compensation control method for two-way communication of a repeater according to claim 7, characterized in that: Step S3 includes the following contents: Based on the nonlinear function model of horizontal polarization state and vertical polarization state, the target delay is first calculated and the arithmetic mean of the two is taken; then, for each polarization state and each frequency point, the delay compensation amount is calculated, that is, the difference between the target delay and the delay of the corresponding polarization state at the corresponding frequency point; then, the trapezoidal numerical integration method is used to convert the delay compensation amount into a phase adjustment amount; finally, the phase adjustment amounts of the horizontal polarization state and the vertical polarization state at all frequency points are integrated into a delay gradient compensation matrix.

9. The delay compensation control method for two-way communication of a repeater according to claim 8, characterized in that: Step S4 includes the following contents: The delay gradient compensation matrix is ​​loaded in the digital pre-equalization module at the transmitter end of the repeater station. The delay gradient compensation matrix contains the phase adjustment amount of the horizontal polarization state and the vertical polarization state at each frequency point; the baseband signal is converted into the frequency domain form through fast Fourier transform and decomposed into horizontal polarization state and vertical polarization state components; for the frequency domain signal component of each polarization state, a phase pre-distortion in the opposite direction to the delay gradient is applied at each frequency point; the pre-distorted frequency domain signal is subjected to inverse fast Fourier transform to obtain a time domain pre-distortion signal and polarization multiplexing is performed; the multiplexed signal is modulated into an optical signal and transmitted through an optical fiber link to compensate for the delay dispersion effect.

10. A time delay compensation control system for two-way communication of a repeater, used to implement the time delay compensation control method for two-way communication of a repeater as claimed in any one of claims 1 to 9, characterized in that: include: Signal separation module, model generation module, compensation calculation module and pre-distortion compensation module; Signal separation module: Separate the orthogonal polarization signal components in the optical fiber link through the polarization diversity receiving module, extract the frequency domain amplitude and phase characteristics, and construct the original data set; Model generation module: Based on the original data set, the model complexity is dynamically adjusted according to the nonlinear characteristics of time delay and phase using polynomial fitting and frequency domain interpolation algorithms to generate a nonlinear function model of time delay varying with frequency under each polarization state; Compensation calculation module: According to the nonlinear function model, the delay compensation amount of each frequency point is reversely calculated and mapped into the frequency domain phase pre-distortion parameter to form a delay gradient compensation matrix covering the entire frequency band; Pre-distortion compensation module: The delay gradient compensation matrix is ​​loaded into the digital pre-equalization module, and a phase pre-distortion in the opposite direction of the nonlinear delay gradient is applied to the baseband signal at the transmitting end to compensate for the delay dispersion effect of the signal at the receiving end.

Images