WO2023005655A1 - 通信方法、装置及系统 - Google Patents

通信方法、装置及系统 Download PDF

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Publication number
WO2023005655A1
WO2023005655A1 PCT/CN2022/105087 CN2022105087W WO2023005655A1 WO 2023005655 A1 WO2023005655 A1 WO 2023005655A1 CN 2022105087 W CN2022105087 W CN 2022105087W WO 2023005655 A1 WO2023005655 A1 WO 2023005655A1
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Prior art keywords
frequency
service signal
frequency offset
module
receiving end
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PCT/CN2022/105087
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English (en)
French (fr)
Inventor
刘玲
赵也
马圣明
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华为技术有限公司
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Publication of WO2023005655A1 publication Critical patent/WO2023005655A1/zh

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/61—Coherent receivers

Definitions

  • the present application relates to the technical field of communication, and in particular to a communication method, device and system.
  • Service signals may be transmitted between communication devices, wherein a communication device sending service signals is called a sending end, and a communication device receiving service signals is called a receiving end.
  • the sending end and the receiving end are usually connected by an optical fiber, and a filter, such as a wavelength selective switch (Wavelength Selective Switch, WSS), is set on the optical fiber.
  • WSS wavelength selective switch
  • the service signal sent from the sending end to the receiving end will be filtered by WSS, and then transmitted to the receiving end.
  • the present application provides a communication method, device and system, which can solve the problem of poor communication effect between the sending end and the receiving end.
  • the technical solution is as follows:
  • a communication method is provided, the method is used at a receiving end, the receiving end is connected to the sending end through an optical fiber, and at least one filter is arranged on the optical fiber, and the method includes: the receiving end receives the After the service signal sent by the sending end, obtain the spectrum information of the service signal, and send the frequency offset parameter of the service signal to the sending end according to the spectrum information; wherein, the frequency offset parameter is used to indicate : at least one information of the offset magnitude and offset direction of the center frequency of the service signal relative to the center frequency of the at least one filter.
  • the transmitting end may adjust the center frequency of the transmitting end according to the frequency offset parameter after receiving the frequency offset parameter sent by the receiving end.
  • the receiving end can send the frequency offset parameter to the transmitting end, and the frequency offset parameter is used to indicate the offset of the center frequency of the service signal relative to the center frequency of at least one filter connected in series on the optical fiber At least one of size and offset direction information. Therefore, the transmitting end may adjust the center frequency of the transmitting end according to the at least one type of information indicated by the frequency offset parameter. In this way, the frequency offset of the service signal is corrected, thereby reducing the ISI of the service signal and reducing the filtering cost of the filter for the service signal.
  • the communication effect between the sending end and the receiving end is guaranteed, so that the service signal between the sending end and the receiving end can be transmitted over a long distance.
  • a communication method is provided, the method is used at a receiving end, the receiving end is connected to the sending end through an optical fiber, and at least one filter is provided on the optical fiber, and the method includes: the receiving end receives the After the service signal sent by the sending end, acquire the spectrum information of the service signal, and send the spectrum information to the sending end.
  • the transmitting end can determine the above-mentioned frequency offset parameter according to the spectrum information, and then adjust the center frequency of the transmitting end according to the frequency offset parameter.
  • the receiving end can send spectrum information to the sending end, so that the sending end can determine the frequency offset parameter according to the spectrum information, and the frequency offset parameter is used to indicate that the center frequency of the service signal is relative to the serial frequency on the optical fiber. at least one of the offset magnitude and offset direction of the center frequency of at least one filter.
  • the transmitting end may adjust the center frequency of the transmitting end according to the at least one type of information indicated by the frequency offset parameter. In this way, the frequency offset of the service signal is corrected, thereby reducing the ISI of the service signal and reducing the filtering cost of the filter for the service signal.
  • the communication effect between the sending end and the receiving end is guaranteed, so that the service signal between the sending end and the receiving end can be transmitted over a long distance.
  • the spectrum information of the service signal may refer to signal spectrum and/or noise spectrum information of the service signal, where the noise spectrum can indicate the impact of noise on the service signal.
  • the service signal will be affected by noise during transmission from the sending end to the receiving end, and the spectrum information can indicate the influence of the noise on the service signal.
  • the spectrum information of the service signal includes a channel response or a spectrum estimation coefficient of the service signal. Both the channel response and the spectrum estimation coefficient can reflect the signal spectrum and/or noise spectrum information of the service signal.
  • the receiving end can perform fast Fourier transform on the channel response to obtain the frequency domain response, and according to the frequency domain response and The baud rate of the service signal is used to obtain the frequency offset parameter.
  • the channel response includes N sampling points, and N represents the number of fast Fourier transform points;
  • the frequency domain response includes the power of the service signal at N frequencies, and the N sampling points One-to-one correspondence with the N frequencies, the power of the service signal at each of the frequencies is obtained by transforming the corresponding sampling points;
  • the receiving end responds according to the frequency domain and the baud rate of the service signal,
  • the receiving end can determine the imaginary part of the spectral estimation coefficients according to the spectral information, and according to the spectral estimation The sign of the imaginary part of the coefficient determines the frequency offset parameter.
  • the at least one type of information indicated by the frequency offset parameter includes the offset direction.
  • the receiving end may determine the imaginary part of the spectral estimation coefficients according to the spectral information, and determine the imaginary part of the spectral estimation coefficients according to the spectral estimation The imaginary part of the coefficient determines the frequency offset parameter.
  • the at least one kind of information indicated by the frequency offset parameter includes the offset direction, and the frequency offset parameter is also used to indicate the absolute value of the imaginary part of the spectral estimation coefficient.
  • the receiving end before the receiving end sends the frequency offset parameter of the service signal to the transmitting end, it may determine that the frequency offset degree of the service signal is greater than a frequency offset degree threshold.
  • the receiving end before the receiving end sends the spectrum information of the service signal to the sending end, it may also determine that the frequency deviation degree of the service signal is greater than a frequency deviation degree threshold.
  • the frequency deviation degree of the service signal is: the frequency deviation degree of the center frequency of the service signal relative to the center frequency of the at least one filter.
  • the receiving end can determine that the frequency deviation degree of the current service signal is relatively high, and at this time, the receiving end can send the frequency deviation parameter in the first aspect or the second frequency deviation parameter to the sending end. Spectrum information in the aspect, so that the transmitting end adjusts its center frequency according to the received information, so as to correct the frequency offset of the service signal.
  • the receiving end can determine that the frequency deviation degree of the current service signal is relatively low. At this time, there is no need to correct the frequency deviation of the service signal.
  • the sending end sends the frequency offset parameter in the first aspect or the spectrum information in the second aspect.
  • the receiving end determines the frequency offset parameter according to the frequency spectrum information, and at least one type of information indicated by the frequency offset parameter includes the size of the offset. At this time, the receiving end may determine that the frequency offset of the service signal is greater than the frequency offset threshold when the offset is greater than the offset threshold.
  • the spectrum information is the spectral estimation coefficient of the service signal.
  • the receiving end can determine that the degree of frequency offset of the service signal is greater than the frequency Offset degree threshold; when the absolute value of the imaginary part of the spectrum estimation coefficient is less than or equal to the absolute value threshold, it is determined that the frequency offset degree of the service signal is less than or equal to the frequency offset degree threshold.
  • the receiving end when the receiving end obtains the spectrum information of the service signal, it may first perform equalization processing on the service signal;
  • the service signal is obtained to obtain the spectrum information.
  • Equalizing the service signal at the receiving end can eliminate the influence of environmental factors (such as optical fiber swing, thunder or lightning, etc.) on the service signal, and improve the accuracy of the obtained spectrum information.
  • the method further includes: when the frequency deviation degree of the service signal is less than or equal to a frequency deviation degree threshold at the receiving end, sending the spectrum information to the transmitting end.
  • the sending end can precompensate the service signal according to the spectrum information.
  • the impact on the service signal during transmission includes: the first impact of the filter on the service signal filtering due to the frequency offset of the service signal, and the second impact other than the first impact (such as the transmission The impact of the photoelectric devices on the end and the receiving end on the filtering of the service signal, and the impact of the filter on the filtering of the service signal when the service signal is not frequency offset).
  • the frequency offset degree of the service signal is less than the frequency offset degree threshold value
  • the first impact can be ignored, and at this time, the spectrum information mainly reflects the above-mentioned second impact. Therefore, when the frequency deviation degree of the service signal is less than the frequency deviation degree threshold, the receiving end can feed back the spectrum information of the service signal to the transmitting end, so that the transmitting end can pre-compensate the service signal according to the spectrum information, so as to eliminate the above-mentioned second influence, further reducing the filtering cost.
  • the method includes: after acquiring the spectral estimation coefficients of the service signal, the receiving end updates the real part of the spectral estimation coefficients according to the first frequency, so as to update the spectral Estimate coefficients; afterward, the receiving end filters the service signal according to the current spectral estimation coefficients.
  • the receiving end may reduce the first frequency, where the first condition includes: the receiving end sends the spectrum information to the sending end. In other words, after the receiving end sends the frequency spectrum information used for precompensation to the sending end, the receiving end may lower the first frequency.
  • the real part of the spectral estimation coefficient is related to eliminating the second impact on the service signal.
  • the transmitting end may perform precompensation on the service signal according to the spectrum information, so as to reduce or eliminate the second impact.
  • the real part of the spectral estimation coefficient will become smaller, and the update frequency of the real part of the spectral estimation coefficient (the above-mentioned first frequency) will be reduced.
  • the ability of the receiving end to eliminate the second influence will be reduced, since the service signal has already Precompensation is performed, so the second effect is not high.
  • the update frequency of the real part of the spectrum estimation coefficient is reduced, the power consumption of the receiving end is reduced.
  • the first condition further includes: the absolute value of the real part is smaller than a first threshold. Since the absolute value of the real part of the spectral estimation coefficient is positively correlated with the ability of the receiving end to eliminate the second impact, when the absolute value of the real part of the spectral estimation coefficient is smaller than the first threshold, it means that the second impact is relatively small. At this time, reducing the update frequency of the real part of the spectral estimation coefficient will reduce the ability of the receiving end to eliminate the second impact, but it can ensure that the service signal filtered by the receiving end is less affected by the second impact.
  • the method includes: after the receiving end acquires the spectral estimation coefficient of the service signal, updating the imaginary part of the spectral estimation coefficient according to the second frequency, so as to updating the spectral estimation coefficient; then, the receiving end filters the service signal according to the current spectral estimation coefficient; when the second condition is satisfied, the receiving end may reduce the second frequency.
  • the second condition includes: the receiving end sends the frequency offset parameter to the sending end.
  • the second condition includes: the receiving end sends the spectrum information to the sending end.
  • the receiving end in the receiving end filters the service signal according to the spectral estimation coefficient
  • the imaginary part in the spectral estimation coefficient is related to eliminating the first impact on the service signal.
  • the sending end can adjust the center frequency of the sending end according to the received information, so as to correct the frequency offset of the service signal .
  • the imaginary part in the spectral estimation coefficient will become smaller, and the update frequency of the imaginary part in the spectral estimation coefficient (the above-mentioned second frequency) will be reduced.
  • the ability of the receiving end to eliminate the first influence will be reduced, due to the degree of frequency offset of the service signal has been reduced, so the degree of frequency deviation of the service signal will not be high.
  • the update frequency of the imaginary part in the spectral estimation coefficient is reduced, the power consumption of the receiving end is reduced, and the power consumption of the receiving end is reduced.
  • the second condition above further includes: the absolute value of the imaginary part of the spectral estimation coefficient is smaller than the second threshold. Since the absolute value of the imaginary part of the spectral estimation coefficient is related to the degree of frequency offset of the service signal, when the absolute value of the imaginary part of the spectral estimation coefficient is smaller than the second threshold, it indicates that the frequency deviation of the service signal is relatively small. Although the update frequency of the imaginary part of the spectral estimation coefficient will reduce the ability of the receiving end to eliminate the first impact, it can ensure that the service signal filtered by the receiving end is less affected by the first impact.
  • a communication method which can be used at the sending end, the sending end is connected to the receiving end through an optical fiber, and at least one filter is arranged on the optical fiber, and the method includes: the sending end acquires After determining the frequency offset parameter of the service signal, adjust the center frequency of the transmitting end according to at least one type of information indicated by the frequency offset parameter.
  • the at least one kind of information indicated by the frequency offset parameter is: at least one of an offset magnitude and an offset direction of the center frequency of the service signal relative to the center frequency of the at least one filter information; the frequency offset parameter is a parameter determined according to spectrum information of the service signal.
  • the sending end can obtain the frequency offset parameter, and the frequency offset parameter is used to indicate the offset of the center frequency of the service signal relative to the center frequency of at least one filter connected in series on the optical fiber and At least one type of information in the offset direction.
  • the transmitting end may adjust the center frequency of the transmitting end according to the at least one type of information indicated by the frequency offset parameter. In this way, the frequency offset of the service signal is corrected, thereby reducing the ISI of the service signal and reducing the filtering cost of the filter for the service signal.
  • the communication effect between the sending end and the receiving end is guaranteed, so that the service signal between the sending end and the receiving end can be transmitted over a long distance.
  • the sending end can adjust the operating frequency of the laser in the sending end when adjusting the center frequency of the sending end (and/or, The frequency of the digital signal in the sending end), so as to realize the adjustment of the center frequency of the sending end.
  • the center frequencies of signals (such as service signals and non-service signals) sent by the sending end are adjusted, so that the frequency offset of the service signal can be corrected.
  • the transmitting end may receive the frequency offset parameter sent by the receiving end.
  • the frequency offset parameter may be determined by the receiving end according to the spectrum information of the service signal.
  • the sending end may also send the above service signal to the sending end.
  • the transmitting end may also receive spectrum information sent by the receiving end, and at this time, the transmitting end may also perform pre-compensation on subsequent service signals to be transmitted according to the spectrum information.
  • the receiving end may send the spectrum information to the sending end.
  • the impact on the service signal during the transmission process includes: the first impact of the filter on the service signal filtering due to the frequency offset of the service signal, and the second impact other than the first impact (such as on the sending end and the receiving end)
  • the influence of optoelectronic devices on the filtering of service signals, and the influence of filters on the filtering of service signals when the service signal is not frequency offset When the frequency offset degree of the service signal is less than the frequency offset degree threshold value, the first impact can be ignored, and at this time, the spectrum information mainly reflects the above-mentioned second impact.
  • the receiving end can feed back the spectrum information of the service signal to the transmitting end, so that the transmitting end can pre-compensate the service signal according to the spectrum information, so as to eliminate the above-mentioned second influence, further reducing the filtering cost.
  • the transmitting end may receive spectrum information of the service signal sent by the receiving end, and determine the frequency offset parameter according to the spectrum information.
  • the sending end may also send the above service signal to the sending end.
  • the process of determining the frequency offset parameter at the transmitting end according to the spectrum information reference may be made to the process of determining the frequency offset parameter at the receiving end according to the spectrum information in the first aspect above, and the present application does not repeat it here.
  • the foregoing frequency offset parameter may be used to indicate at least one parameter of an offset magnitude and an offset direction.
  • the transmitting end needs to determine this parameter in other ways.
  • the sender can determine the adjustment direction of the center frequency of the sender according to the offset direction, and the sender can also obtain the sender's The adjustment amount of the center frequency.
  • the size of the adjustment amount can be pre-configured in the sending end, can also be randomly generated by the sending end, or can be sent to the sending end by other devices, which is not limited in this application.
  • the transmitting end can use the offset as the adjustment value of the central frequency of the transmitting end, and the transmitting end can also Get the adjustment direction of the center frequency of the sender.
  • the adjustment direction may be pre-configured in the sending end, or randomly generated by the sending end, or sent to the sending end by other devices, which is not limited in this application.
  • the transmitter can obtain the frequency offset parameter again (such as receiving the frequency offset parameter sent by the transmitter), and judge whether the offset value indicated by the frequency offset parameter is reduced .
  • the magnitude of the offset indicated by the frequency offset parameter decreases, it means that the adjustment direction of the center frequency of the sender is correct, and the center frequency of the sender can be continuously adjusted in this adjustment direction. If the offset indicated by the frequency offset parameter increases, it means that the adjustment direction of the center frequency of the sender is wrong, and the sender can change the adjustment direction of its center frequency to adjust the center frequency of the sender in the opposite direction. .
  • the transmitting end may judge whether the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold, and only adjust the frequency deviation degree of the service signal when the frequency deviation degree is greater than the frequency deviation degree threshold value. Center frequency. When the frequency deviation degree of the service signal is less than or equal to the frequency deviation degree threshold, the transmitting end does not need to adjust its center frequency.
  • the frequency offset parameter obtained by the sending end is used to indicate the size of the above-mentioned offset.
  • the process of the sending end judging whether the frequency offset degree is greater than the frequency offset degree threshold can refer to the receiving end according to the offset The process of judging whether the degree of frequency offset is greater than the threshold of the degree of frequency offset based on the magnitude of the quantity is not repeated in this application.
  • the frequency offset parameter (or spectrum information) sent by the receiving end includes the imaginary part of the spectrum estimation coefficient.
  • the sending end can judge whether the frequency offset degree of the service signal is greater than the frequency offset degree threshold according to the imaginary part of the spectrum estimation coefficient.
  • the process of the sending end judging whether the degree of frequency offset is greater than the threshold of the frequency offset degree according to the imaginary part of the spectral estimation coefficient can refer to the process of the receiving end judging whether the degree of frequency deviation is greater than the threshold value of the frequency deviation degree according to the imaginary part of the spectral estimation coefficient.
  • both the sending end and the receiving end judge whether the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold, the accuracy of the judgment result is improved through the double judgment of the sending end and the receiving end.
  • a communication device for a receiving end, the receiving end is connected to the sending end through an optical fiber, and at least one filter is provided on the optical fiber, and the communication device includes: a receiving module, an acquisition module and The first sending module.
  • the receiving module is used to receive the service signal sent by the sending end; the obtaining module is used to obtain the spectrum information of the service signal; the first sending module is used to send the service signal to the sending end according to the spectrum information
  • the frequency offset parameter of the signal; the frequency offset parameter is used to indicate: at least one of the offset magnitude and offset direction of the center frequency of the service signal relative to the center frequency of the at least one filter.
  • the first sending module can send the frequency offset parameter to the sending end, and the frequency offset parameter is used to indicate the deviation of the center frequency of the service signal from the center frequency of at least one filter connected in series on the optical fiber. At least one of the displacement magnitude and the displacement direction. Therefore, the transmitting end may adjust the center frequency of the transmitting end according to the at least one type of information indicated by the frequency offset parameter. In this way, the frequency offset of the service signal is corrected, thereby reducing the ISI of the service signal and reducing the filtering cost of the filter for the service signal.
  • the communication effect between the sending end and the receiving end is guaranteed, so that the service signal between the sending end and the receiving end can be transmitted over a long distance.
  • a communication device is provided, the communication device is used for a receiving end, the receiving end is connected to the sending end through an optical fiber, at least one filter is provided on the optical fiber, and the communication device includes: a receiving module, An acquisition module and a first sending module.
  • the receiving module is used to receive the service signal sent by the sending end
  • the obtaining module is used to obtain the spectrum information of the service signal
  • the first sending module is used to send the spectrum information to the sending end.
  • the transmitting end may determine the frequency offset parameter according to the spectrum information, and then adjust the center frequency of the transmitting end according to the frequency offset parameter.
  • the first sending module can send spectrum information to the sending end, so that the sending end can determine the frequency offset parameter according to the spectrum information, and the frequency offset parameter is used to indicate that the center frequency of the service signal is relative to the optical fiber at least one of the offset magnitude and the offset direction of the center frequency of the at least one filter connected in series.
  • the transmitting end may adjust the center frequency of the transmitting end according to the at least one type of information indicated by the frequency offset parameter. In this way, the frequency offset of the service signal is corrected, thereby reducing the ISI of the service signal and reducing the filtering cost of the filter for the service signal.
  • the communication effect between the sending end and the receiving end is guaranteed, so that the service signal between the sending end and the receiving end can be transmitted over a long distance.
  • the spectrum information of the service signal may refer to signal spectrum and/or noise spectrum information of the service signal, where the noise spectrum can indicate the impact of noise on the service signal.
  • the service signal will be affected by noise during transmission from the sending end to the receiving end, and the spectrum information can indicate the influence of the noise on the service signal.
  • the spectrum information of the service signal includes channel response or spectrum estimation coefficient of the service signal. Both the channel response and the spectrum estimation coefficient can reflect the signal spectrum and/or noise spectrum information of the service signal.
  • the communication devices in the fourth aspect and the fifth aspect further include: a first processing module and a second processing module, the first processing module is configured to process the The channel response is subjected to fast Fourier transform to obtain a frequency domain response; the second processing module is configured to obtain the frequency offset parameter according to the frequency domain response and the baud rate of the service signal.
  • the channel response includes N sampling points, and N represents the number of fast Fourier transform points;
  • the frequency domain response includes the power of the service signal at N frequencies, and the N sampling points One-to-one correspondence with the N frequencies, the power of the service signal at each of the frequencies is obtained through corresponding sampling point transformation;
  • the communication devices in the above fourth and fifth aspects further include: a first determining module and a second determining module.
  • the first determining module is configured to determine the imaginary part of the spectral estimation coefficient according to the spectral information; the second determining module is configured to determine the frequency offset parameter according to the positive or negative of the imaginary part of the spectral estimation coefficient, the At least one type of information includes the offset direction.
  • the communication apparatuses in the fourth aspect and the fifth aspect further include: a third determining module and a fourth determining module.
  • a third determination module configured to determine the imaginary part of the spectral estimation coefficient according to the spectrum information;
  • a fourth determination module configured to determine the frequency offset parameter according to the imaginary part of the spectral estimation coefficient, the at least one The information includes the offset direction, and the frequency offset parameter is also used to indicate the absolute value of the imaginary part of the spectral estimation coefficient.
  • the receiving end before the receiving end sends the frequency offset parameter of the service signal to the sending end, it may also use the fifth determination module to determine that the frequency offset degree of the service signal is greater than the frequency offset degree threshold.
  • the fifth determination module before the receiving end sends the frequency spectrum information of the service signal to the sending end, the fifth determination module may also determine that the frequency deviation degree of the service signal is greater than a frequency deviation degree threshold.
  • the frequency deviation degree of the service signal is: the frequency deviation degree of the center frequency of the service signal relative to the center frequency of the at least one filter.
  • the receiving end can determine that the frequency deviation degree of the current service signal is relatively high, and at this time, the receiving end can send the frequency deviation parameter in the fourth aspect or the fifth aspect to the sending end. Spectrum information in the aspect, so that the transmitting end adjusts its center frequency according to the received information, so as to correct the frequency offset of the service signal.
  • the receiving end can determine that the frequency deviation degree of the current service signal is relatively low. At this time, there is no need to correct the frequency deviation of the service signal.
  • the sending end sends the frequency offset parameter in the fourth aspect or the spectrum information in the fifth aspect.
  • the fifth determining module determines the frequency offset parameter according to the frequency spectrum information, and at least one type of information indicated by the frequency offset parameter includes the offset amount.
  • the receiving end may determine that the frequency offset of the service signal is greater than the frequency offset threshold when the offset is greater than the offset threshold.
  • the spectrum information is the spectral estimation coefficient of the service signal.
  • the receiving end can use the sixth determination module to determine the service signal
  • the frequency offset degree of the frequency offset degree is greater than the frequency offset degree threshold; when the absolute value of the imaginary part of the spectrum estimation coefficient is less than or equal to the absolute value threshold, it is determined that the frequency offset degree of the service signal is less than or equal to the frequency offset degree threshold.
  • the acquisition module when the acquisition module acquires the spectrum information of the service signal, it may first perform equalization processing on the service signal; The service signal is obtained to obtain the spectrum information. Equalizing the service signal at the receiving end can eliminate the influence of environmental factors (such as optical fiber swing, thunder or lightning, etc.) on the service signal, and improve the accuracy of the obtained spectrum information.
  • environmental factors such as optical fiber swing, thunder or lightning, etc.
  • the communication device further includes: a second sending module, configured to send to the sending end when the frequency deviation degree of the service signal is less than or equal to a frequency deviation degree threshold value Spectrum information described above.
  • the sending end can precompensate the service signal according to the spectrum information.
  • the impact on the service signal during transmission includes: the first impact of the filter on the service signal filtering due to the frequency offset of the service signal, and the second impact other than the first impact (such as the transmission The impact of the photoelectric devices on the end and the receiving end on the filtering of the service signal, and the impact of the filter on the filtering of the service signal when the service signal is not frequency offset).
  • the frequency offset degree of the service signal is less than the frequency offset degree threshold value
  • the first impact can be ignored, and at this time, the spectrum information mainly reflects the above-mentioned second impact. Therefore, when the frequency deviation degree of the service signal is less than the frequency deviation degree threshold, the receiving end can feed back the spectrum information of the service signal to the transmitting end, so that the transmitting end can pre-compensate the service signal according to the spectrum information, so as to eliminate the above-mentioned second influence, further reducing the filtering cost.
  • the communication device includes: a first updating module, a first filtering module, and a first reducing module.
  • the first updating module is configured to update the real part of the spectral estimation coefficient according to the first frequency after acquiring the spectral estimation coefficient of the service signal, so as to update the spectral estimation coefficient;
  • the first filtering module uses Filtering the service signal according to the current spectral estimation coefficient;
  • a first reducing module configured to reduce the first frequency when a first condition is met, and the first condition includes: the receiving end Send the spectrum information to the sending end. In other words, after the receiving end sends the frequency spectrum information used for precompensation to the sending end, the receiving end may lower the first frequency.
  • the real part of the spectral estimation coefficient is related to eliminating the second impact on the service signal.
  • the transmitting end may perform precompensation on the service signal according to the spectrum information, so as to reduce or eliminate the second impact.
  • the real part of the spectral estimation coefficient will become smaller, and the update frequency of the real part of the spectral estimation coefficient (the above-mentioned first frequency) will be reduced.
  • the ability of the receiving end to eliminate the second influence will be reduced, since the service signal has already Precompensation is performed, so the second effect is not high.
  • the update frequency of the real part of the spectrum estimation coefficient is reduced, the power consumption of the receiving end is reduced.
  • the first condition further includes: the absolute value of the real part is smaller than a first threshold. Since the absolute value of the real part of the spectral estimation coefficient is positively correlated with the ability of the receiving end to eliminate the second impact, when the absolute value of the real part of the spectral estimation coefficient is smaller than the first threshold, it means that the second impact is relatively small. At this time, reducing the update frequency of the real part of the spectral estimation coefficient will reduce the ability of the receiving end to eliminate the second impact, but it can ensure that the service signal filtered by the receiving end is less affected by the second impact.
  • the communication device includes: a second updating module, a second filtering module and a second reducing module.
  • the second updating module is configured to update the imaginary part of the spectral estimation coefficient according to the second frequency after acquiring the spectral estimation coefficient of the service signal, so as to update the spectral estimation coefficient;
  • the second filtering module is configured to update the spectral estimation coefficient according to the second frequency
  • the current spectrum estimation coefficient is used to filter the service signal;
  • the second reducing module is configured to reduce the second frequency when the second condition is satisfied.
  • the second condition includes: the receiving end sends the frequency offset parameter to the sending end.
  • the second condition includes: the receiving end sends the spectrum information to the sending end.
  • the receiving end in the receiving end filters the service signal according to the spectral estimation coefficient
  • the imaginary part in the spectral estimation coefficient is related to eliminating the first impact on the service signal.
  • the sending end can adjust the center frequency of the sending end according to the received information, so as to correct the frequency offset of the service signal .
  • the imaginary part in the spectral estimation coefficient will become smaller, and the update frequency of the imaginary part in the spectral estimation coefficient (the above-mentioned second frequency) will be reduced.
  • the ability of the receiving end to eliminate the first influence will be reduced, due to the degree of frequency offset of the service signal has been reduced, so the degree of frequency deviation of the service signal will not be high.
  • the update frequency of the imaginary part in the spectral estimation coefficient is reduced, the power consumption of the receiving end is reduced, and the power consumption of the receiving end is reduced.
  • the second condition above further includes: the absolute value of the imaginary part of the spectral estimation coefficient is smaller than a second threshold. Since the absolute value of the imaginary part of the spectral estimation coefficient is related to the degree of frequency offset of the service signal, when the absolute value of the imaginary part of the spectral estimation coefficient is smaller than the second threshold, it indicates that the frequency deviation of the service signal is relatively small. Although the update frequency of the imaginary part of the spectral estimation coefficient will reduce the ability of the receiving end to eliminate the first impact, it can ensure that the service signal filtered by the receiving end is less affected by the first impact.
  • a communication device which can be used at a sending end, the sending end is connected to the receiving end through an optical fiber, at least one filter is provided on the optical fiber, and the communication device includes: an acquisition module and regulation modules.
  • the acquisition module is used to acquire the frequency offset parameter of the service signal
  • the frequency offset parameter is used to indicate: the offset amount and offset direction of the center frequency of the service signal relative to the center frequency of the at least one filter at least one type of information
  • the frequency offset parameter is a parameter determined according to the spectrum information of the service signal
  • an adjustment module is configured to adjust the transmission according to the at least one type of information indicated by the frequency offset parameter end center frequency.
  • the acquisition module can acquire the frequency offset parameter, and the frequency offset parameter is used to indicate the offset of the center frequency of the service signal relative to the center frequency of at least one filter connected in series on the optical fiber and At least one type of information in the offset direction.
  • the adjusting module can adjust the center frequency of the transmitting end according to the at least one kind of information indicated by the frequency offset parameter. In this way, the frequency offset of the service signal is corrected, thereby reducing the ISI of the service signal and reducing the filtering cost of the filter for the service signal.
  • the communication effect between the sending end and the receiving end is guaranteed, so that the service signal between the sending end and the receiving end can be transmitted over a long distance.
  • the adjustment module can adjust the operating frequency of the laser in the sending end when adjusting the center frequency of the sending end (and/or, The frequency of the digital signal in the sending end), so as to realize the adjustment of the center frequency of the sending end.
  • the center frequencies of signals (such as service signals and non-service signals) sent by the sending end are adjusted, so that the frequency offset of the service signal can be corrected.
  • the acquisition module to acquire the frequency offset parameter.
  • the acquiring module may receive the frequency offset parameter sent by the receiving end.
  • the frequency offset parameter may be determined by the receiving end according to the spectrum information of the service signal.
  • the sending end may also use the sending module to send the above service signal to the sending end.
  • the communication device further includes a receiving module and a pre-compensation module, the receiving module can be used to receive the spectrum information sent by the receiving end, and the pre-compensation module can be used to adjust the subsequent services to be sent according to the spectrum information The signal is precompensated.
  • the receiving end may send the spectrum information to the sending end.
  • the impact on the service signal during the transmission process includes: the first impact of the filter on the service signal filtering due to the frequency offset of the service signal, and the second impact other than the first impact (such as on the sending end and the receiving end)
  • the influence of optoelectronic devices on the filtering of service signals, and the influence of filters on the filtering of service signals when the service signal is not frequency offset When the frequency offset degree of the service signal is less than the frequency offset degree threshold value, the first impact can be ignored, and at this time, the spectrum information mainly reflects the above-mentioned second impact.
  • the receiving end can feed back the spectrum information of the service signal to the transmitting end, so that the transmitting end can pre-compensate the service signal according to the spectrum information, so as to eliminate the above-mentioned second influence, further reducing the filtering cost.
  • the acquiring module may receive spectrum information of the service signal sent by the receiving end, and determine the frequency offset parameter according to the spectrum information.
  • the sending end may also use the sending module to send the above service signal to the sending end.
  • the process of the acquisition module determining the frequency offset parameter according to the spectrum information may refer to the process of the receiving end determining the frequency offset parameter according to the spectrum information in the above first aspect, and the present application does not repeat it here.
  • the foregoing frequency offset parameter may be used to indicate at least one parameter of an offset magnitude and an offset direction.
  • the acquisition module needs to determine this parameter in other ways.
  • the acquisition module can determine the adjustment direction of the center frequency of the transmitter according to the offset direction, and the acquisition module can also acquire the transmitter's The adjustment amount of the center frequency.
  • the adjustment amount can be pre-configured in the acquisition module, or randomly generated by the acquisition module, or sent to the acquisition module by other devices, which is not limited in this application.
  • the acquisition module can use the offset as the adjustment amount of the center frequency of the transmitting end, and the acquisition module can also Get the adjustment direction of the center frequency of the sender.
  • the adjustment direction may be pre-configured in the acquisition module, or randomly generated by the acquisition module, or sent to the acquisition module by other devices, which is not limited in this application.
  • the acquisition module can acquire the frequency offset parameter again (such as receiving the frequency offset parameter sent by the transmitter), and judge whether the offset value indicated by the frequency offset parameter is reduced .
  • the adjustment module adjusts the central frequency of the transmitting end in the correct direction, and the central frequency of the transmitting end can be continuously adjusted in this direction. If the offset value indicated by the frequency offset parameter increases, it means that the adjustment module adjusts the center frequency of the transmitter in the wrong direction, and the subsequent adjustment module can change the adjustment direction of its center frequency to adjust the center of the transmitter in the opposite direction. frequency.
  • the adjustment module can judge whether the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold, and only adjust the frequency deviation degree of the service signal when it is determined that the frequency deviation degree is greater than the frequency deviation degree threshold value The center frequency of the sender. When the frequency deviation degree of the service signal is less than or equal to the frequency deviation degree threshold, the adjustment module does not need to adjust its center frequency.
  • the adjustment module to judge whether the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold, and the following two implementation ways will be taken as examples to explain.
  • the frequency offset parameter is used to indicate the size of the above-mentioned offset.
  • the adjustment module judges whether the frequency offset is greater than the frequency offset threshold. The process of determining whether the deviation degree is greater than the frequency deviation degree threshold is not described here in this application.
  • the frequency offset parameter (or spectrum information) sent by the receiving end includes the imaginary part of the spectrum estimation coefficient.
  • the adjustment module can judge whether the frequency offset degree of the service signal is greater than the frequency offset degree threshold according to the imaginary part of the spectrum estimation coefficient.
  • the process of the adjustment module judging whether the degree of frequency offset is greater than the threshold value of the frequency offset degree according to the imaginary part of the spectral estimation coefficient can refer to the process of the receiving end judging whether the degree of frequency deviation is greater than the threshold value of the degree of frequency deviation according to the imaginary part of the spectral estimation coefficient.
  • both the sending end and the receiving end judge whether the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold, the accuracy of the judgment result is improved through the double judgment of the sending end and the receiving end.
  • a communication system in a seventh aspect, includes: a sending end and a receiving end.
  • the sending end includes the communication device described in any design of the fourth aspect or the fifth aspect; the receiving end includes the communication device described in any design of the sixth aspect.
  • FIG. 1 is a schematic structural diagram of a communication system provided by an embodiment of the present application.
  • FIG. 2 is a schematic structural diagram of another communication system provided by an embodiment of the present application.
  • FIG. 3 is a schematic diagram of a power spectrum of a service signal and a power spectrum of a WSS provided in an embodiment of the present application;
  • FIG. 4 is a schematic diagram of a power spectrum of another service signal and a power spectrum of a WSS provided by an embodiment of the present application;
  • FIG. 5 is a schematic diagram of another power spectrum of a service signal and a power spectrum of a WSS provided by an embodiment of the present application;
  • FIG. 6 is a flowchart of a communication method provided by an embodiment of the present application.
  • FIG. 7 is a schematic diagram of functional modules of a receiving end provided by an embodiment of the present application.
  • FIG. 8 is a schematic diagram of functional modules of a sending end and a receiving end provided in an embodiment of the present application.
  • FIG. 9 is a schematic diagram of a frequency domain response of a service signal provided in an embodiment of the present application under three frequency offset situations;
  • FIG. 10 is a schematic diagram of frequency domain responses of another service signal provided in the embodiment of the present application under the three frequency offset situations;
  • FIG. 11 is a schematic diagram of changes in the imaginary part of a spectral estimation coefficient provided by an embodiment of the present application.
  • Fig. 12 is a schematic diagram of another variation of the imaginary part of the spectrum estimation coefficient provided by the embodiment of the present application.
  • Fig. 13 is a schematic diagram of another variation of the imaginary part of the spectrum estimation coefficient provided by the embodiment of the present application.
  • FIG. 14 is a schematic structural diagram of a communication device provided by an embodiment of the present application.
  • FIG. 15 is a schematic structural diagram of another communication device provided by an embodiment of the present application.
  • FIG. 1 is a schematic structural diagram of a communication system provided by an embodiment of the present application.
  • the communication system includes a sending end and a receiving end, and the sending end and the receiving end are connected through an optical fiber link.
  • the optical fiber link includes: an optical fiber, and an optical relay set on the optical fiber (such as WSS in FIG. 1 ).
  • An optical relay may include at least one filter, signal amplifier, and the like. Also, when the optical relay includes a plurality of filters, these filters can be connected in series on the optical fiber.
  • the above-mentioned filter is an optical filter.
  • the optical filter may be a WSS, a comb filter (interleaver, ITL), or an arrayed waveguide grating (arrayed waveguide grating, AWG).
  • ITL interleaver
  • AWG arrayed waveguide grating
  • an optical relay including one WSS is taken as an example.
  • the sending end may include: an electrical transmitter and an optical transmitter.
  • the electrical transmitter includes: a digital signal modulation module and a digital-to-analog conversion module.
  • Optical transmitters include: lasers and optical modulators, etc.
  • the digital signal modulation module is used to modulate the digital signal according to the data to be transmitted;
  • the digital-to-analog conversion module is used to convert the digital signal into an analog signal;
  • the laser is used to emit laser light;
  • the optical modulator is used to modulate the laser light emitted by the laser into light according to the analog signal Signal (such as coherent optical signal or incoherent optical signal, etc.), and send the optical signal to the optical fiber.
  • the analog signal Signal such as coherent optical signal or incoherent optical signal, etc.
  • the receiving end includes: an optical receiver and an electrical receiver.
  • the optical receiver includes an optical detector, etc.
  • the electrical receiver includes an analog-to-digital conversion module and a signal demodulation module.
  • the optical detector is used to receive the optical signal on the optical fiber and convert the optical signal into an analog signal;
  • the analog-to-digital conversion module is used to convert the analog signal into a digital signal;
  • the signal demodulation module is used to demodulate the digital signal, Get the data that the sender needs to transmit.
  • Optical signals transmitted on optical fibers include service signals.
  • the service signal sent by the sending end is filtered by the optical fiber transmission and filter (such as WSS) and received by the receiving end.
  • filter such as WSS
  • the filter filters the service signal
  • the filter allows signals in a certain frequency band to pass through, and prohibits signals outside the frequency band from passing through.
  • the center frequency of the frequency band of the signal that the filter allows is called the center frequency of the filter.
  • the center frequencies of different filters can be the same or different.
  • the frequency deviation of the service signal means that there is an offset between the center frequency of the service signal and the center frequency of at least one filter set on the optical fiber.
  • the center frequency of the at least one filter is also the center frequency of the one filter.
  • the center frequency of the at least one filter is also the cascaded center frequency of the plurality of filters. It should be noted that the filtering effect of the multiple filters on the signal is the same as that of the filter with the cascaded center frequency on the signal.
  • each point on the power spectrum of the service signal corresponds to a frequency and a power
  • the point represents the power of the service signal at the frequency.
  • Each point on the power spectrum of WSS also corresponds to a frequency and a power.
  • the signal that WSS allows to pass satisfies a condition: the frequency of the signal is the frequency corresponding to a certain point on the power spectrum, and the power of the signal is less than that corresponding to the point. power.
  • WSS will filter them out.
  • the deviation of the center frequency of the service signal relative to the center frequency of the WSS is shown in Figure 3
  • the signals represented by the left and right parts of the power spectrum of the service signal in Figure 3 will be detected by the WSS filter out.
  • FIG. 4 When the deviation of the center frequency of the service signal relative to the center frequency of the WSS is shown in FIG. 4, the part of the power spectrum of the service signal in FIG. The signal will be filtered by WSS.
  • ISI Inter Symbol Interference
  • the embodiment of the present application provides a communication method, in which the receiving end can send a frequency offset parameter to the sending end, and the frequency offset parameter is used to indicate the center frequency of the service signal relative to the center frequency of at least one filter connected in series on the optical fiber At least one of the offset size and offset direction information.
  • the sending end may adjust the center frequency of the sending end according to the at least one type of information indicated by the frequency offset parameter. In this way, the frequency offset of the service signal is corrected, thereby reducing the ISI of the service signal and reducing the filtering cost of the filter for the service signal.
  • the communication effect between the sending end and the receiving end is guaranteed, so that the service signal between the sending end and the receiving end can be transmitted over a long distance.
  • Fig. 6 is a flow chart of a communication method provided in the embodiment of the present application, and the method can be used in the communication system provided in the embodiment of the present application (the communication system shown in Fig. 1 or Fig. 2 ). As shown in Figure 6, the method includes:
  • the sending end sends a service signal to the receiving end.
  • the service signal sent by the sending end is filtered by the optical fiber transmission and filter (such as WSS) and received by the receiving end.
  • WSS optical fiber transmission and filter
  • the receiving end performs equalization processing on the service signal.
  • the receiving end After receiving the service signal, the receiving end will perform equalization processing on the service signal (such as compensation for polarization-related damage to the service signal, carrier recovery, and elimination of part of ISI, etc.) to eliminate the environmental factors (such as fiber swing , thunder or lightning, etc.) effects.
  • the receiving end can perform equalization processing on the service signal based on any algorithm.
  • the arbitrary algorithm can be a classic least squares method (Least Squares Method, LS), a gradient descent method (such as a minimum mean square error (Least Mean Square, LMS) algorithm), etc.
  • the receiving end acquires spectrum information of the service signal according to the service signal after equalization processing.
  • the spectrum information of the service signal may refer to the information of the signal spectrum and/or the noise spectrum of the service signal, where the noise spectrum can indicate the impact of noise on the service signal.
  • the service signal will be affected by noise during transmission from the sending end to the receiving end, and the spectrum information can indicate the influence of the noise on the service signal.
  • the spectrum information of the service signal includes channel response or spectrum estimation coefficient of the service signal. Both the channel response and the spectrum estimation coefficient can reflect the signal spectrum and/or noise spectrum information of the service signal.
  • the channel filtering includes: the filtering of the service signal by the filter on the optical fiber, and the filtering of the service signal by the photoelectric devices in the transmitting end and the receiving end.
  • Spectral estimation is a general term for algorithms for power spectral density and spectral estimation of random signal sequences.
  • Spectral estimation includes classical spectral estimation (non-parametric spectral estimation not based on coefficients) and modern spectral estimation (parametric spectral estimation based on coefficients), parametric spectrum
  • the estimated coefficients are generally referred to as spectral estimation coefficients.
  • Spectrum information can also include other parameters besides channel response and spectral estimation coefficients, such as signal spectrum (also called direct signal spectrum), noise spectrum transformed by signal spectrum, or other equivalent symmetric Spectrum of characteristics, etc., are not limited in this embodiment of the present application.
  • signal spectrum also called direct signal spectrum
  • noise spectrum transformed by signal spectrum or other equivalent symmetric Spectrum of characteristics, etc.
  • the receiving end can use a traditional spectral estimation algorithm to obtain the spectral estimation coefficient.
  • the spectral estimation algorithm for this transmission is, for example, the AR-Burg algorithm (autoregressive-Burg algorithm, Burg means Burg algorithm, Burg is a classic spectral estimation algorithm), etc.
  • the receiving end may first make a decision (hard decision or soft decision) on the service signal after equalization processing, and obtain the service signal after the decision. Afterwards, the receiving end may subtract the determined service signal from the equalized service signal to obtain channel noise. Finally, the receiving end can perform spectral estimation on the channel noise to obtain spectral estimation coefficients, and use the spectral estimation coefficients as spectral information.
  • a decision hard decision or soft decision
  • the receiving end can first perform forward error correction code (Forward Error Correction, FEC) decoding and reconstruction on the equalized service signal in order to obtain the reconstructed service signal.
  • FEC Forward Error Correction
  • reconstructing the service signal refers to remapping the service signal decoded by the FEC.
  • the receiving end may subtract the reconstructed service signal from the equalized service signal to obtain channel noise.
  • the receiving end can perform spectral estimation on the channel noise to obtain spectral estimation coefficients, and use the spectral estimation coefficients as spectral information.
  • the receiving end includes a module (called NFC module) for performing narrowband filtering compensation (Narrowband Filtering Compensation, NFC), because the NFC module usually performs NFC processing on the service signal, based on the spectral estimation coefficient. Filtering is performed. Therefore, in S103, the receiving end can acquire the spectral estimation coefficients based on the filtering of the NFC module, and use the spectral estimation coefficients as spectral information. In this way, the receiving end only needs to calculate the spectral estimation coefficients once during the process of performing the NFC processing and executing S103, which avoids the waste of computing resources caused by multiple calculations of the spectral estimation coefficients.
  • NFC module narrowband Filtering Compensation
  • the NFC module may use any method to obtain spectrum estimation coefficients, such as Burg algorithm, Levinson-Durbin algorithm, and the like.
  • the spectral estimation coefficients on which the NFC module filters are based include multiple spectral estimation coefficients corresponding to the multiple taps one-to-one.
  • the receiving end may select any spectral estimation coefficient except the spectral estimation coefficient corresponding to the first tap among the plurality of spectral estimation coefficients as the spectral information.
  • the receiving end may use the spectral estimation coefficient corresponding to the second or third tap among the plurality of taps as the spectral information.
  • the receiving end acquires the spectrum information once as an example.
  • the receiving end may also acquire the spectrum information multiple times in S103, and use the average value of the multiple acquired spectrum information as the finally acquired spectrum information , to improve the accuracy of the acquired spectrum information.
  • the average value of the frequency spectrum information obtained multiple times may be any average value, such as an arithmetic average value, a square average value, a harmonic average value, or a weighted average value.
  • the receiving end may also use the NFC module to perform NFC processing on the equalized service signal to obtain the NFC-processed service signal. Afterwards, the receiving end may obtain the above spectrum information based on the NFC-processed service signal.
  • the receiving end acquires spectrum information based on the NFC-processed service signal, refer to the process that the receiving end acquires spectrum information based on the equalized service signal, and this embodiment of the present application does not repeat it here.
  • performing NFC processing on the service signal can compensate for the ISI introduced by the service signal due to the limited channel bandwidth. If the receiving end acquires spectrum information based on the NFC-processed service signal, the acquired spectrum information can also avoid the impact of limited channel bandwidth and improve the accuracy of the spectrum information.
  • the receiving end sends the frequency offset parameter of the service signal to the sending end according to the frequency spectrum information of the service signal.
  • the frequency offset parameter of the service signal is used to indicate at least one of the above offset size and offset direction, for example, the frequency offset parameter is used to indicate the offset size, or the frequency offset parameter is used to indicate the offset direction, or, the frequency offset parameter is used to indicate the magnitude and direction of the offset.
  • This embodiment of the present application does not limit it.
  • the receiving end After obtaining the spectrum information of the service signal, the receiving end needs to determine the frequency offset parameter of the service signal according to the spectrum information of the service signal, and then send the frequency offset parameter to the transmitting end.
  • the receiving end sends the frequency offset parameter to the sending end according to the spectrum information as an example.
  • the receiving end may also directly send the spectrum information of the service signal to the sending end in S104, and then the sending end The frequency offset parameter of the service signal is determined according to the spectrum information.
  • the receiving end may send information for frequency adjustment to the sending end, and the information may include frequency offset parameters or spectrum information, which is not limited in this embodiment of the present application.
  • the sending end adjusts the center frequency of the sending end according to the frequency offset parameter of the service signal.
  • the sending end needs to obtain the frequency offset parameter.
  • the sending end can directly obtain the frequency offset parameter; when the information used for frequency adjustment sent by the receiving end in S104 is spectrum information, the sending end The frequency offset parameter needs to be determined according to the spectrum information to obtain the frequency offset parameter.
  • the frequency offset parameter indicates at least one of the above-mentioned offset size and offset direction
  • the sending end can determine the adjustment direction and adjustment amount of the center frequency of the sending end according to the at least one type of information indicated by the frequency offset parameter, and then Adjust the center frequency of the sending end according to the adjustment direction and the adjustment amount.
  • the frequency offset parameter indicating the magnitude of the offset and the offset direction as an example.
  • the sending end can determine that the adjustment direction of the center frequency of the sending end is the direction of frequency reduction , the adjustment amount is X, and the sending end can reduce the center frequency of the sending end by X.
  • the sending end can determine that the adjustment direction of the center frequency of the sending end is the direction of frequency increase, and the adjustment amount The size is X, and the sender can increase its center frequency by X.
  • the sending end can adjust the operating frequency of the laser in the sending end (and/or, the digital signal in the sending end) when adjusting the center frequency of the sending end.
  • the frequency of the signal so as to realize the adjustment of the center frequency of the sending end.
  • the central frequencies of signals (such as service signals and non-service signals) sent by the transmitting end are adjusted, so that the frequency offset of the service signal can be corrected.
  • the receiving end (or sending end) needs to determine the frequency offset parameter of the service signal according to the frequency spectrum information of the service signal.
  • the receiving end (or sending end) to determine the frequency offset parameter according to the spectrum information
  • the following will take several implementable ways for the receiving end to determine the frequency offset parameter according to the spectrum information as examples to explain.
  • the manner in which the transmitting end determines the frequency offset parameter according to the spectrum information may refer to the manner in which the receiving end determines the frequency offset parameter according to the spectrum information, and details are not described in this embodiment of the present application.
  • the spectrum information is the channel response of the service signal.
  • the receiving end may first perform fast Fourier transform on the channel response to obtain the frequency domain response. Afterwards, according to the frequency domain response and the baud rate of the service signal (the unit may be hertz), the frequency offset parameter of the service signal is obtained.
  • the frequency offset parameter is used to indicate: an offset amount and an offset direction of the center frequency of the service signal relative to the center frequency of the at least one filter.
  • the channel response is the response of the channel in the time domain
  • the frequency domain response is the response of the channel in the frequency domain.
  • the channel response can be converted from the time domain to the frequency domain by using the fast Fourier transform (FFT), so as to obtain the frequency domain response.
  • FFT fast Fourier transform
  • FFT has the number of points N, and N is usually 2 to the nth power (n ⁇ 1), such as 64, 128 or 256, etc.
  • the receiving end performs FFT on the channel response, it can first sample the channel response according to the number N of FFT points to obtain N sampling points; then, transform each sampling point in the N sampling points to obtain the service signal at Power at N frequencies (ie frequency domain response).
  • N sampling points are in one-to-one correspondence with the N frequencies, and the power of the service signal at each frequency is obtained by transforming the corresponding sampling points.
  • the channel response includes sampling points 0.1, 0.2, and 0.3
  • the frequency domain response includes: the power 2.1 of the service signal at frequency 1.1, the power 2.2 of the service signal at frequency 1.2, and the service signal at frequency 2.1.
  • Power 2.3 under 1.3.
  • Power 2.1 is obtained by transforming sampling point 0.1;
  • power 2.2 is obtained by transforming sampling point 0.2;
  • power 2.3 is obtained by transforming sampling point 0.3.
  • the receiving end can substitute the frequency domain response and the baud rate of the service signal into the frequency offset formula to obtain the frequency offset parameter.
  • the absolute value of the frequency offset parameter obtained by the receiving end according to the frequency offset formula can be used to represent the magnitude of the above offset, and the sign of the frequency offset parameter can be used to represent the above offset direction.
  • the frequency offset parameter when the frequency offset parameter is a positive value, the frequency offset parameter is used to indicate that the offset direction is right offset (that is, the center frequency of the service signal is greater than the center frequency of the at least one filter); when the frequency offset parameter is a negative value When , the frequency offset parameter is used to indicate that the offset direction is left offset (that is, the center frequency of the service signal is smaller than the center frequency of the at least one filter).
  • the frequency offset parameter when the frequency offset parameter is a positive value, the frequency offset parameter is used to indicate that the offset direction is left; when the frequency offset parameter is a negative value, the frequency offset parameter is used to indicate that the offset direction is right.
  • the spectrum information is the spectrum estimation coefficient of the service signal.
  • the receiving end may determine the imaginary part of the spectral estimation coefficient, and determine the frequency offset parameter according to the sign of the imaginary part.
  • the frequency offset parameter is used to indicate an offset direction of the center frequency of the service signal relative to the center frequency of the at least one filter.
  • the sign of the imaginary part is opposite to the above offset direction.
  • the offset direction is left-biased.
  • the shift direction is right biased.
  • the receiving end may also check the sign of the imaginary part. For example, when the absolute value of the imaginary part is less than the absolute value threshold, the checked imaginary part is 0; when the absolute value of the imaginary part is greater than or equal to the absolute value threshold, the checked imaginary part is the same as the one before checking. Afterwards, the receiving end can determine the frequency offset parameter according to the positive or negative of the checked imaginary part.
  • the spectrum information is the spectrum estimation coefficient of the service signal.
  • the receiving end may determine an imaginary part of the spectral estimation coefficient, and determine a frequency offset parameter according to the imaginary part (for example, use the imaginary part as a frequency offset parameter).
  • the frequency offset parameter is used to indicate an offset direction of the center frequency of the service signal relative to the center frequency of the at least one filter, and the frequency offset parameter is also used to indicate the absolute value of the imaginary part.
  • the receiving end can refer to the process of obtaining frequency offset parameters in any one of the first three possible ways to obtain at least a parameter. Afterwards, the receiving end obtains the frequency offset parameter according to the at least one parameter.
  • the frequency offset parameter includes the adjustment amount of the center frequency of the transmitting end; when the at least one parameter includes an offset direction, the frequency offset parameter includes the adjustment of the transmitting end to Adjustment direction of center frequency.
  • the frequency offset parameters received by the sending end include the adjustment direction and/or the adjustment amount, and the sending end can adjust the center frequency of the sending end according to the adjustment direction and/or the adjustment amount in the frequency offset parameter, reducing the frequency of the sending end. load.
  • the frequency offset parameter is used as an example to indicate the magnitude of the offset and the offset direction.
  • the transmitting end needs to determine this parameter in other ways.
  • the sender can determine the adjustment direction of the center frequency of the sender according to the offset direction, and the sender can also obtain the sender's The adjustment amount of the center frequency.
  • the size of the adjustment amount may be pre-configured in the sending end, may also be randomly generated by the sending end, or may be sent to the sending end by other devices, which is not limited in this embodiment of the present application.
  • the transmitting end can use the offset as the adjustment value of the central frequency of the transmitting end, and the transmitting end can also Get the adjustment direction of the center frequency of the sender.
  • the adjustment direction may be pre-configured in the sending end, may be randomly generated by the sending end, or may be sent to the sending end by other devices, which is not limited in this embodiment of the present application.
  • the transmitter can obtain the frequency offset parameter again (such as receiving the frequency offset parameter sent by the transmitter), and judge whether the offset value indicated by the frequency offset parameter is reduced .
  • the magnitude of the offset indicated by the frequency offset parameter decreases, it means that the adjustment direction of the center frequency of the sender is correct, and the center frequency of the sender can be continuously adjusted in this adjustment direction. If the offset indicated by the frequency offset parameter increases, it means that the adjustment direction of the center frequency of the sender is wrong, and the sender can change the adjustment direction of its center frequency to adjust the center frequency of the sender in the opposite direction. .
  • the receiving end directly executes S104 (sending frequency offset parameters to the sending end according to spectrum information) after S103.
  • the receiving end may also perform S104 only when the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold. When the frequency deviation degree of the service signal is less than or equal to the frequency deviation degree threshold, the receiving end does not need to perform S104.
  • the receiving end can determine that the frequency deviation degree of the current service signal is relatively high, and at this time, the receiving end can perform S104, so that the transmitting end can adjust its center frequency according to the frequency deviation parameter, thereby The frequency offset of the service signal is corrected.
  • the receiving end can determine that the frequency deviation degree of the current service signal is low, and there is no need to correct the frequency deviation of the service signal at this time, therefore, the receiving end does not need to perform S104.
  • the frequency offset parameter is used to indicate the size of the offset.
  • the receiving end can determine whether the offset of the center frequency of the service signal relative to the center frequency of the at least one filter is greater than the offset Shift size threshold. When the offset of the center frequency of the service signal relative to the center frequency of at least one filter is greater than the offset threshold, the receiving end may determine that the frequency offset of the service signal is greater than the frequency offset threshold. When the offset of the center frequency of the service signal relative to the center frequency of at least one filter is less than or equal to the offset threshold, the receiving end may determine that the frequency offset of the service signal is less than or equal to the frequency offset threshold.
  • the spectrum information is the spectral estimation coefficient of the service signal.
  • the receiving end can determine that the degree of frequency offset of the service signal is greater than the frequency Offset degree threshold; when the absolute value of the imaginary part of the spectrum estimation coefficient is less than or equal to the absolute value threshold, it is determined that the frequency offset degree of the service signal is less than or equal to the frequency offset degree threshold.
  • the receiving end before the receiving end sends the frequency offset parameter to the sending end, it may not judge whether the frequency offset degree of the service signal is greater than the frequency offset degree threshold, which is not limited in this embodiment of the present application.
  • the sending end may judge whether the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold before S105, and determine Only when the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold, S105 is executed to adjust the center frequency of the transmitting end.
  • the transmitting end does not need to adjust its center frequency.
  • the frequency offset parameter is used to indicate the size of the above-mentioned offset.
  • the sending end judges whether the frequency offset degree is greater than the frequency offset threshold.
  • the embodiment of the present application does not repeat the first implementation manner of the deviation degree threshold.
  • the sending end may judge whether the frequency offset degree of the service signal is greater than the frequency offset degree threshold according to the imaginary part of the spectrum estimation coefficient.
  • the frequency offset parameter (or spectrum information) sent by the receiving end in S104 includes the imaginary part of the spectrum estimation coefficient.
  • the sending end and the receiving end may repeatedly execute the communication method provided in the embodiment of the present application to continuously judge whether the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold.
  • S104 and S105 are executed, so as to adjust the frequency deviation degree of the service signal to a state less than or equal to the frequency deviation degree threshold.
  • the receiving end executes S104 only when the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold. Then, when the frequency deviation degree of the service signal is less than or equal to the frequency deviation degree threshold, the receiving end does not need to execute S104. At this time, the receiving end can send information for pre-compensation to the sending end, and the information includes the spectrum information of the service signal. The sending end can perform precompensation on the service signal according to the information for precompensation.
  • the impact on the service signal during the transmission process includes: the first impact of the filter on the service signal filtering due to the frequency offset of the service signal, and the second impact other than the first impact (such as on the sending end and the receiving end)
  • the influence of optoelectronic devices on the filtering of service signals, and the influence of filters on the filtering of service signals when the service signal is not frequency offset When the frequency offset degree of the service signal is less than the frequency offset degree threshold value, the first impact can be ignored, and at this time, the spectrum information mainly reflects the above-mentioned second impact.
  • the receiving end can feed back the spectrum information of the service signal to the transmitting end, so that the transmitting end can pre-compensate the service signal according to the spectrum information, so as to eliminate the above-mentioned second influence, further reducing the filtering cost.
  • the sending end includes a digital signal processing (digital signal processing, DSP) module, and the sending end can use the DSP module to pre-compensate the service signal according to the spectrum information of the service signal.
  • DSP digital signal processing
  • the NFC module when the receiving end has an NFC module, the NFC module will obtain the spectral estimation coefficient of the service signal, update the real part of the spectral estimation coefficient according to the first frequency, and update the imaginary part of the spectral estimation coefficient according to the second frequency, to update the spectral estimation coefficients.
  • the NFC module also filters the service signal according to the current spectrum estimation coefficient.
  • the receiving end may adjust the first frequency according to the first condition. For example, when the first condition is satisfied, the receiving end may reduce the first frequency (the reduced first frequency may be greater than or equal to zero).
  • the first condition includes: the receiving end sends spectrum information to the sending end. In other words, after the receiving end sends the frequency spectrum information used for pre-compensation to the sending end, the receiving end can lower the first frequency.
  • the real part of the spectral estimation coefficient is related to eliminating the second impact on the service signal.
  • the transmitting end may perform precompensation on the service signal according to the spectrum information, so as to reduce or eliminate the second impact.
  • the real part of the spectral estimation coefficient will become smaller, and the update frequency of the real part of the spectral estimation coefficient (the above-mentioned first frequency) will be reduced.
  • the ability of the NFC module to eliminate the second impact will be reduced, since the service signal has already Precompensation is performed, so the second effect is not high.
  • the update frequency of the real part of the spectral estimation coefficient is reduced, the power consumption of the NFC module is reduced, and the power consumption of the receiving end is reduced.
  • the above first condition further includes: the absolute value of the real part of the spectrum estimation coefficient is smaller than the first threshold. Since the absolute value of the real part of the spectrum estimation coefficient is positively correlated with the ability of the NFC module to eliminate the second influence, when the absolute value of the real part of the spectrum estimation coefficient is smaller than the first threshold, it means that the second influence is relatively small. At this time, reducing the update frequency of the real part of the spectral estimation coefficient will reduce the ability of the NFC module to eliminate the second influence, but it can ensure that the service signal filtered by the NFC module is less affected by the second influence.
  • the receiving end may periodically adjust the first frequency according to the first condition, wherein the period for the receiving end to adjust the first frequency may be any period, such as a minute-level period, an hour-level period or a day-level period cycle etc.
  • the receiving end may also adjust the second frequency according to the second condition. For example, when the second condition is satisfied, the receiving end may reduce the second frequency (the reduced second frequency may be greater than or equal to zero), wherein the second condition includes: the receiving end sends information for frequency adjustment to the transmitting end (such as frequency offset parameter above).
  • the NFC module in the receiving end filters the service signal according to the spectral estimation coefficient
  • the imaginary part in the spectral estimation coefficient is related to eliminating the first impact on the service signal.
  • the sending end can adjust the center frequency of the sending end according to the frequency offset parameter, so as to correct the frequency offset of the service signal to a certain extent.
  • the imaginary part in the spectral estimation coefficient will become smaller, and the update frequency of the imaginary part in the spectral estimation coefficient (the above-mentioned second frequency) will be reduced.
  • the ability of the NFC module to eliminate the first influence will be reduced, due to the degree of frequency deviation of the service signal has been reduced, so the degree of frequency deviation of the service signal will not be high.
  • the update frequency of the imaginary part of the spectral estimation coefficient is reduced, the power consumption of the NFC module is reduced, and the power consumption of the receiving end is reduced.
  • the second condition above further includes: the absolute value of the imaginary part of the spectral estimation coefficient is smaller than the second threshold. Since the absolute value of the imaginary part of the spectral estimation coefficient is related to the degree of frequency offset of the service signal, when the absolute value of the imaginary part of the spectral estimation coefficient is smaller than the second threshold, it indicates that the frequency deviation of the service signal is relatively small. Although the update frequency of the imaginary part of the spectral estimation coefficient will reduce the ability of the NFC module to eliminate the first impact, it can ensure that the service signal filtered by the NFC module is less affected by the first impact.
  • the receiving end may periodically adjust the second frequency according to the second condition, wherein the period for the receiving end to adjust the second frequency may be any period, such as a minute-level period, an hour-level period, or a day-level period cycle etc.
  • the receiving end includes: a receiving module, an equalization module, a spectrum information acquisition module, a frequency offset parameter acquisition module, and a sending module.
  • the receiving module is used for receiving the service signal sent by the sending end.
  • the equalization module is used for equalizing the service signal to obtain the equalized service signal.
  • the spectrum information acquiring module is used to acquire the spectrum information of the service signal according to the equalized service signal.
  • the frequency offset parameter acquisition module is used to obtain a frequency offset parameter different from the spectrum information according to the spectrum information.
  • the sending module is used to send the frequency offset parameter to the sending end.
  • the spectrum information acquisition module to acquire spectrum information.
  • the receiving end further includes a judging module, which is used for judging the equalized service signal.
  • the spectrum information acquisition module can be used to subtract the determined service signal from the equalized service signal to obtain channel noise, and then obtain a spectrum estimation coefficient (an example of spectrum information) according to the channel noise.
  • the receiving end further includes an FEC decoding module and a reconstruction module.
  • the FEC decoding module is used to perform FEC decoding on the equalized service signal
  • the reconstruction module is used to reconstruct the decoded service signal.
  • the spectrum information acquisition module can be used to subtract the reconstructed service signal from the equalized service signal to obtain channel noise, and then obtain the spectral estimation coefficient according to the channel noise.
  • the receiving end further includes an NFC module, and the receiving end can perform NFC processing on the equalized service signal to obtain the NFC processed service signal.
  • the receiving end may acquire the foregoing spectrum information based on the NFC-processed service signal.
  • the receiving end acquires spectrum information based on the NFC-processed service signal, refer to the process that the receiving end acquires spectrum information based on the equalized service signal, and this embodiment of the present application does not repeat it here.
  • the judgment module can make a judgment on the NFC-processed service signal, and the spectrum information acquisition module can subtract the NFC-processed service signal from the determined service signal. Signal, get the channel noise, and then get the spectral estimation coefficient according to the channel noise.
  • the FEC decoding module can be used to sequentially perform FEC decoding on the NFC-processed service signals, and the spectrum information acquisition module can be used to convert the NFC-processed business signals
  • the reconstructed service signal is subtracted from the signal to obtain the channel noise, and then the spectral estimation coefficient is obtained according to the channel noise.
  • the receiving end may not acquire the foregoing spectrum information based on the NFC-processed service signal.
  • the receiving end may further include a selection module, and the selection module is used to select whether the service signal on which the spectrum information is obtained is an equalized service signal or an NFC-processed service signal.
  • the selection module is further configured to input the selected signal into the decision module and the spectrum information acquisition module respectively.
  • the selection module is further configured to input the selected signal into the spectrum information acquisition module.
  • the receiving end may further include other modules besides the modules shown in FIG. 7 .
  • the receiving end includes: coherent receiver (Integrated Coherent Receiver, ICR) module, analog to digital converter (analog to digital converter, ADC) module, clock recovery (time recovery, TR) module, equalization module, NFC module and FEC decoding module.
  • the TR module, the equalization module and the NFC module can be implemented in a DSP module (not shown in FIG. 8 ) at the receiving end.
  • the ICR module is used to realize the function of the photodetector in Fig. 2
  • the TR module, equalization module, NFC module and FEC decoding module are used to realize the function of the signal demodulation module in Fig. 2 .
  • the sending end includes: an FEC coding module, a DSP module, a digital to analog converter (digital to analog converter, DAC) module, a driving module, a modulating module and a laser.
  • the FEC coding module and the DSP module are used to realize the function of the digital signal modulation module in FIG. 2
  • the modulation module is used to realize the function of the modulator in FIG. 2 .
  • the FEC encoding module is used to perform FEC encoding on the data to be transmitted to obtain a digital signal; the DSP module is used to precompensate the digital signal, and the DAC module is used to convert the precompensated digital signal into an analog signal
  • the driving module is used to amplify the electrical signal (the above analog signal) output by the DAC; the laser is used to emit laser light; the modulation module is used to modulate the laser light emitted by the laser according to the analog signal to obtain a service signal.
  • the service signal will be transmitted to the receiving end through the optical fiber and at least one WSS on the optical fiber.
  • the ICR module is used to convert the received service signal into an analog signal; the ADC module is used to convert the analog signal into a digital signal; the TR module is used to recover the clock of the digital signal; the equalization module is used to The digital signal after clock recovery is equalized to obtain the service signal after equalization processing; the NFC module is used to perform NFC processing on the service signal after equalization processing to obtain the service signal after NFC processing; the FEC decoding module is used to process the NFC After the service signal is decoded by FEC, the data to be transmitted by the sending end is obtained.
  • the receiving end also includes a frequency offset module.
  • the frequency offset module has the functions of the spectrum information acquisition module and the decision module in FIG. 7 .
  • the frequency offset module is connected to the equalization module for obtaining the above-mentioned spectrum information.
  • the frequency offset module is connected to the NFC module for obtaining the above-mentioned spectrum information according to the NFC-processed service signal output by the NFC module.
  • the frequency offset module has the functions of the spectrum information acquisition module and the reconstruction module in FIG. 7 .
  • the frequency offset module is connected with the equalization module and the FEC decoding module, and is used for the equalized service signal output by the equalization module and the FEC decoding module.
  • the service signal decoded by the coding module is used to obtain the above spectrum information.
  • the frequency offset module is connected with the FEC decoding module and the NFC module, and is used to output the NFC-processed service signal according to the NFC module, and the FEC The decoding module obtains the above-mentioned spectrum information from the decoded service signal.
  • the frequency offset module can be connected to the transmitting end (for example, connected to the DSP module in the transmitting end) for sending frequency offset parameters to the transmitting end according to the spectrum information .
  • each module in the receiving end shown in FIG. 7 and FIG. 8 can be implemented by software and/or hardware, and different modules can be independent of each other or integrated into one module, which is not limited in the embodiment of the present application .
  • the receiving end can send the frequency offset parameter to the sending end according to the service signal sent by the sending end, so as to instruct the sending end to adjust its center frequency, and then realize the correction of the frequency offset of the service signal .
  • the receiving end can send the frequency offset parameter to the sending end according to the service signal sent by the sending end, so as to instruct the sending end to adjust its center frequency, and then realize the correction of the frequency offset of the service signal .
  • there are some schemes for correcting the frequency offset of the service signal but these schemes all have some problems, and the problems existing in these schemes will be described in detail below.
  • Solution (1) before sending a service signal to the receiving end, the sending end sends a pilot sequence (or training sequence) to the receiving end.
  • the receiving end can instruct the transmitting end to adjust the working frequency of the laser according to the received pilot sequence (or training sequence), so as to correct the offset between the center frequency of the transmitting end and the center frequency of the at least one filter.
  • sending the pilot sequence (or training sequence) from the transmitting end to the receiving end will occupy a certain spectrum resource, making the utilization rate of the spectrum resource low.
  • the sending end does not need to send pilot sequences or training sequences to the receiving end, thus avoiding the occupation of spectrum resources by sending these sequences and avoiding the situation of low utilization of spectrum resources.
  • the receiving end reads the average bit error rate (Bit Error Rate, BER) of the signal sent by the sending end, and then instructs the sending end to adjust its center frequency according to the average BER. Afterwards, the receiving end reads the average BER again, and determines the variation trend of the average BER. If the change trend of the average BER is a downward trend, it means that the direction in which the transmitter adjusts its center frequency is correct. At this time, the receiver can continue to instruct the transmitter to adjust the center frequency in this direction. If the change trend of the average BER is an upward trend, it means that the direction in which the sending end adjusted its center frequency was wrong. At this time, the receiving end can instruct the sending end to adjust the above-mentioned center frequency in the opposite direction. Repeat this until the average BER reaches the local optimum.
  • Bit Error Rate, BER Bit Error Rate
  • the first time the transmitter adjusts its center frequency is blind tuning, and blind tuning tends not to converge, and it is easy to find the above-mentioned local optimal value, so that the frequency offset of the service signal cannot be adjusted to a relatively small state.
  • the average BER determined by the receiving end will be affected by environmental factors (such as optical fiber swings, thunder, lightning, etc.), resulting in low accuracy of the average BER. Therefore, the receiving end instructs the sending end to adjust its center frequency according to the average BER. The effect is poor.
  • the frequency offset parameter fed back by the receiving end to the sending end can indicate at least one of the offset amount and the offset direction.
  • the sending end adjusts the center frequency according to these information and is not a blind adjustment. , so there is no problem of non-convergence, and the frequency offset of the service signal can be adjusted to a relatively small state.
  • the spectrum information based on the frequency offset parameter sent by the receiving end is determined according to the service signal after equalization processing, and the influence of environmental factors on the service signal is eliminated during the process of equalization processing on the service signal. Therefore, the information indicated by the frequency offset parameter is more accurate, and the transmitting end can correct the frequency offset of the service signal according to the frequency offset parameter. precise estimate.
  • Solution (3) The receiving end extracts the power spectrum of the signal sent by the sending end, and determines the adjustment direction of the center frequency of the sending end according to the symmetry of the power spectrum, and then instructs the sending end to adjust its center frequency in this adjustment direction.
  • the receiving end can only indicate the adjustment direction to the sending end, but cannot indicate the adjustment amount, and the effect of the sending end adjusting its center frequency is poor.
  • storing and analyzing the power spectrum at the receiving end requires a lot of resources, which affects the normal operation of the receiving end.
  • the power spectrum extracted by the receiving end will be affected by environmental factors (such as optical fiber swings, thunder, lightning, etc.), resulting in low accuracy of the power spectrum. Therefore, the accuracy of the adjustment direction determined by the receiving end based on the power spectrum Lower, and then the receiving end instructs the sending end to adjust its center frequency less effectively.
  • the frequency offset parameter sent by the receiving end to the sending end can indicate the offset direction and the offset amount, so the effect of adjusting the center frequency of the sending end is better.
  • the spectral information is the spectral estimation coefficient
  • the receiving end includes an NFC module
  • the existing NFC module can be used to obtain the spectral estimation coefficient without occupying other resources to obtain the spectral information, which reduces the impact on the normal operation of the receiving end. Influence.
  • the spectrum information based on the frequency offset parameters sent by the receiving end is determined according to the service signal after equalization processing, so the sending end can correct the frequency offset of the service signal according to the frequency offset parameters. An accurate estimate of at least one of the magnitude of the offset and the direction of the offset.
  • the filter is WSS as an example
  • Example (1) assuming that the receiving end adopts the first achievable method of determining frequency offset parameters, at this time, the spectrum information is the channel response of the service signal, and the receiving end can first perform fast Fourier transform on the channel response to obtain the frequency domain response, and then The frequency offset parameter of the service signal is obtained according to the frequency domain response and the baud rate of the service signal.
  • the frequency domain responses of the service signal under three frequency offset situations are shown in Fig. 9 .
  • These three frequency deviation situations include: the frequency deviation of the center frequency of the service signal relative to the center frequencies of the 27 WSSs is 2.5 gigahertz (GHz) Frequency deviation case 1, the center frequency of the service signal relative to the center frequencies of the 27 WSSs Frequency offset case 2 where the frequency offset is -2.5 GHz, and frequency offset case 3 where the frequency offset of the center frequency of the service signal relative to the center frequencies of the 27 WSSs is 0 GHz.
  • GHz gigahertz
  • the abscissa in FIG. 9 represents the frequency, and the unit is GHz, and the ordinate represents the power of the service signal at a certain frequency, and the unit is respectively (dB). Moreover, the frequency with the median value of 0 GHz on the abscissa is the cutoff frequency at the current signal baud rate. In the frequency domain response under each frequency offset situation shown in FIG. 9 , the difference between the frequency with the smallest power and the cutoff frequency is the frequency offset parameter determined by the receiving end.
  • the difference between the frequency with the smallest power and the cutoff frequency is 2.10 GHz, and the frequency offset parameter is 2.10 GHz (similar to 2.5 GHz).
  • the difference between the frequency with the smallest power and the cutoff frequency is -2.27GHz, and the frequency offset parameter is -2.27GHz (similar to -2.5GHz).
  • the difference between the frequency with the smallest power and the cutoff frequency is 0.07GHz (not shown in Figure 9), and the frequency offset parameter is 0.07GHz (similar to 0GHz).
  • Fig. 9 frequency deviation case 1 in which the frequency deviation of the center frequency of the service signal relative to the center frequencies of the 27 WSSs is 2 GHz, the center frequency of the service signal is relative to the frequency deviation of the 27 WSSs Frequency offset case 2 where the frequency offset of the center frequency is -2 GHz, and frequency offset case 3 where the frequency offset of the center frequency of the service signal relative to the center frequencies of the 27 WSSs is 0 GHz. Then, the frequency domain responses of the service signal under these three frequency offset situations are shown in FIG. 10 .
  • the difference between the frequency with the smallest power and the cutoff frequency is 1.84 GHz, and the frequency offset parameter is 2.10 GHz (similar to 2 GHz).
  • the difference between the frequency with the smallest power and the cutoff frequency is -1.64GHz, and the frequency offset parameter is -1.64GHz (similar to -2GHz).
  • the difference between the frequency with the smallest power and the cutoff frequency is 0.07GHz, and the frequency offset parameter is 0.07GHz (similar to 0GHz).
  • the offset direction indicated by the frequency offset parameter determined in the embodiment of the present application is relatively similar to the actual offset direction, and the offset indicated by the frequency offset parameter is also relatively similar to the actual offset. In this way, after the transmitting end adjusts its center frequency according to the frequency offset parameter, the frequency offset of the service signal can be effectively corrected.
  • the receiving end adopts the second implementable manner of determining the frequency offset parameter, and at this time, the spectrum information is the spectrum estimation coefficient of the service signal.
  • the receiving end can determine the frequency offset parameter according to the sign of the imaginary part of the spectrum estimation coefficient.
  • the frequency offset parameter is used to indicate the frequency offset direction of the service signal (the direction of the offset of the center frequency of the service signal relative to the center frequencies of the above-mentioned 27 WSSs.
  • the spectral estimation coefficient is the spectral estimation coefficient based on which the NFC module performs filtering, and the NFC module has 4 taps
  • the NFC module performs filtering based on the four spectral estimation coefficients corresponding to the four taps.
  • the modulation format of the service signal is a quadrature amplitude modulation (Quadrature Amplitude Modulation, QAM) format
  • the capacity of the channel between the sending end and the receiving end is 400 GHz/s.
  • QAM Quadrature Amplitude Modulation
  • the receiving end may use the spectral estimation coefficient corresponding to the second tap as the frequency offset parameter.
  • the greater the frequency deviation of the center frequency of the service signal relative to the center frequency of the 27 WSSs, the greater the imaginary part of the spectral estimation coefficient corresponding to the second tap, and the frequency deviation direction of the service signal is the same as that of the second tap
  • the sign of the imaginary part of the corresponding spectral estimation coefficient is opposite.
  • the frequency offset parameter determined by the receiving end according to the sign of the imaginary part can be used for the indicated offset
  • the direction is left-biased (the center frequency of the service signal is less than the center frequency of 27 WSSs).
  • the frequency offset parameter determined by the receiving end according to the positive or negative of the imaginary part can be used to indicate that the offset direction is right offset (the center of the service signal frequency greater than the center frequency of 27 WSS).
  • the offset direction indicated by the frequency offset parameter determined in the embodiment of the present application is consistent with the actual offset direction. In this way, after the transmitting end adjusts its center frequency according to the frequency offset parameter, the frequency offset of the service signal can be effectively corrected. In addition, it is known through experiments that the more WSSs connected in series on the optical fiber, the greater the absolute value of the real part of the spectral estimation coefficient.
  • the communication device needs to include hardware and/or software corresponding to each function module.
  • the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed by hardware or computer software drives hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different ways to implement the described functions in combination with the embodiments for each specific application, but such implementation should not be regarded as exceeding the scope of the present application.
  • each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module.
  • the above integrated modules may be implemented in the form of hardware.
  • FIG. 14 is a block diagram of a communication device provided by an embodiment of the present application.
  • the communication device may be, for example, the receiving end in the foregoing embodiments.
  • the receiving end is connected to the sending end through an optical fiber, and at least one filter is arranged on the optical fiber.
  • the communication device includes: a receiving module 1401 , an acquiring module 1402 and a first sending module 1403 .
  • the receiving module 1401 is configured to receive a service signal sent by the sending end.
  • the acquiring module 1402 is configured to acquire the spectrum information of the service signal; the operations performed by the acquiring module 1402 can refer to the content related to the receiving end in the above S102 and S103.
  • the first sending module 1403 is configured to send the frequency offset parameter of the service signal to the sending end according to the spectrum information; the frequency offset parameter is used to indicate that the center frequency of the service signal is relative to the at least one filter at least one of the offset magnitude and offset direction of the center frequency of the frequency converter.
  • the operations performed by the first sending module 1403 reference may be made to the content related to the receiving end in S104 above.
  • the receiving module 1401 is configured to receive the service signal sent by the sending end, and the operations performed by the receiving module 1401 may refer to the content related to the receiving end in S101 above.
  • the acquiring module 1402 is configured to acquire the spectrum information of the service signal, and the operations performed by the acquiring module 1402 may refer to the contents related to the receiving end in the above S102 and S103.
  • the first sending module 1403 is configured to send the frequency spectrum information to the sending end. In this case, after receiving the spectrum information of the service signal sent by the receiving end, the transmitting end may determine the frequency offset parameter according to the spectrum information, and then adjust the center frequency of the transmitting end according to the frequency offset parameter.
  • the first sending module can send the frequency offset parameter to the sending end, and the frequency offset parameter is used to indicate that the center frequency of the service signal is relative to at least one filter connected in series on the optical fiber. at least one of the offset magnitude and offset direction of the center frequency of the Alternatively, the first sending module can send spectrum information to the sending end, so that the sending end can determine the frequency offset parameter according to the spectrum information, and the frequency offset parameter is used to indicate that the center frequency of the service signal is relative to the center of at least one filter connected in series on the optical fiber At least one of the frequency offset magnitude and the offset direction information.
  • the transmitting end may adjust the center frequency of the transmitting end according to the at least one type of information indicated by the frequency offset parameter.
  • the frequency offset of the service signal is corrected, thereby reducing the ISI of the service signal and reducing the filtering cost of the filter for the service signal.
  • the communication effect between the sending end and the receiving end is guaranteed, so that the service signal between the sending end and the receiving end can be transmitted over a long distance.
  • the receiving module 1401, the obtaining module 1402 and the first sending module 1403 may be realized by means of software and/or hardware.
  • the receiving module 1401, the obtaining module 1402 and the first sending module 1403 may all be realized in a processor at the receiving end.
  • the spectrum information of the service signal may refer to the signal spectrum and/or noise spectrum information of the service signal, where the noise spectrum can indicate the impact of noise on the service signal. Influence.
  • the service signal will be affected by noise during transmission from the sending end to the receiving end, and the spectrum information can indicate the influence of the noise on the service signal.
  • the spectrum information of the service signal includes a channel response or a spectrum estimation coefficient of the service signal. Both the channel response and the spectrum estimation coefficient can reflect the signal spectrum and/or noise spectrum information of the service signal.
  • the communication devices in the above-mentioned first and second implementable manners further include: a first processing module (not shown in FIG. 14 ) and a second Two processing modules (not shown in Figure 14), the first processing module is used to perform fast Fourier transform on the channel response to obtain the frequency domain response; the second processing module is used to obtain the frequency domain response according to the frequency domain response and the The baud rate of the service signal is used to obtain the frequency offset parameter.
  • the first processing module and the second processing module may be implemented by means of software and/or hardware, for example, both the first processing module and the second processing module may be implemented in a processor at the receiving end.
  • the channel response includes N sampling points, and N represents the number of fast Fourier transform points;
  • the frequency domain response includes the power of the service signal at N frequencies, and the N sampling points One-to-one correspondence with the N frequencies, the power of the service signal at each of the frequencies is obtained through corresponding sampling point transformation;
  • the communication devices in the above-mentioned first and second implementable manners further include: a first determination module (not shown in FIG. 14 ) and a second determination module (not shown in FIG. 14 ).
  • the first determining module is configured to determine the imaginary part of the spectral estimation coefficient according to the spectral information; the second determining module is configured to determine the frequency offset parameter according to the positive or negative of the imaginary part of the spectral estimation coefficient, the At least one type of information includes the offset direction.
  • the first determination module and the second determination module may be implemented by means of software and/or hardware, for example, both the first determination module and the second determination module may be implemented in a processor at the receiving end.
  • the communication devices in the above-mentioned first and second implementable manners further include: a third determination module (not shown in FIG. 14 ) and a fourth determining module (not shown in FIG. 14 ).
  • a third determination module configured to determine the imaginary part of the spectral estimation coefficient according to the spectrum information;
  • a fourth determination module configured to determine the frequency offset parameter according to the imaginary part of the spectral estimation coefficient, the at least one The information includes the offset direction, and the frequency offset parameter is also used to indicate the absolute value of the imaginary part of the spectral estimation coefficient.
  • the third determining module and the fourth determining module may be implemented by means of software and/or hardware, for example, both the third determining module and the fourth determining module may be implemented in a processor at the receiving end.
  • the receiving end before the receiving end sends the frequency offset parameter of the service signal to the sending end, it may also use a fifth determining module (not shown in FIG. 14 ) to determine the The frequency offset degree of the service signal is greater than the frequency offset degree threshold.
  • a fifth determining module before the receiving end sends the spectrum information of the service signal to the transmitting end, it may also use a fifth determination module (not shown in FIG. 14 ) to determine the frequency spectrum of the service signal.
  • the deviation degree is greater than the frequency deviation degree threshold.
  • the frequency deviation degree of the service signal is: the frequency deviation degree of the center frequency of the service signal relative to the center frequency of the at least one filter.
  • the receiving end can determine that the frequency offset degree of the current service signal is relatively high, and at this time, the receiving end can send the frequency offset parameter in the first achievable manner to the sending end Or the spectrum information in the second practicable way, so that the transmitting end adjusts its center frequency according to the received information, so as to correct the frequency offset of the service signal.
  • the receiving end can determine that the frequency deviation degree of the current service signal is relatively low. At this time, there is no need to correct the frequency deviation of the service signal.
  • the sending end sends the frequency offset parameter in the first implementable manner or the spectrum information in the second implementable manner.
  • the fifth determining module may be implemented by means of software and/or hardware.
  • the fifth determining module may be implemented in a processor at the receiving end.
  • the fifth determining module determines the frequency offset parameter according to the frequency spectrum information, and at least one type of information indicated by the frequency offset parameter includes the offset amount.
  • the receiving end may determine that the frequency offset of the service signal is greater than the frequency offset threshold when the offset is greater than the offset threshold.
  • the spectrum information is the spectral estimation coefficient of the service signal.
  • the receiving end can use the sixth determination module (FIG. 14 Not shown in ) to determine that the frequency offset of the service signal is greater than the frequency offset threshold; when the absolute value of the imaginary part of the spectrum estimation coefficient is less than or equal to the absolute value threshold, determine that the frequency offset of the service signal is less than or equal to the frequency offset threshold .
  • the sixth determination module may be implemented by means of software and/or hardware, for example, the sixth determination module may be implemented in a processor at the receiving end.
  • the acquisition module 1402 may first perform equalization processing on the service signal; then, according to Obtain the frequency spectrum information of the equalized service signal.
  • Equalizing the service signal at the receiving end can eliminate the influence of environmental factors (such as optical fiber swing, thunder or lightning, etc.) on the service signal, and improve the accuracy of the obtained spectrum information.
  • the part in the obtaining module 1402 for equalizing the service signal may be implemented in the DSP at the receiving end.
  • the communication device further includes: a second sending module (not shown in FIG. 14 ), configured to be used when the frequency deviation degree of the service signal is less than or equal to the frequency deviation When the degree threshold is exceeded, send the spectrum information to the sending end.
  • the sending end can precompensate the service signal according to the spectrum information.
  • the impact on the service signal during transmission includes: the first impact of the filter on the service signal filtering due to the frequency offset of the service signal, and the second impact other than the first impact (such as the transmission The impact of the photoelectric devices on the end and the receiving end on the filtering of the service signal, and the impact of the filter on the filtering of the service signal when the service signal is not frequency offset).
  • the second sending module may be implemented by means of software and/or hardware, for example, the second sending module may be implemented in a processor at the receiving end.
  • the communication device includes: a first updating module (not shown in FIG. 14 ), a first filtering module (not shown in FIG. 14 ), and a first reducing module (not shown in Figure 14).
  • the first updating module is configured to update the real part of the spectral estimation coefficient according to the first frequency after acquiring the spectral estimation coefficient of the service signal, so as to update the spectral estimation coefficient;
  • the first filtering module uses Filtering the service signal according to the current spectral estimation coefficient;
  • a first reducing module configured to reduce the first frequency when a first condition is met, and the first condition includes: the receiving end Send the spectrum information to the sending end.
  • the receiving end may lower the first frequency.
  • the real part of the spectral estimation coefficient is related to eliminating the second impact on the service signal.
  • the sending end can perform pre-compensation on the service signal according to the spectrum information to reduce or eliminate the second impact.
  • the first updating module, the first filtering module and the first reducing module can be realized by means of software and/or hardware, for example, the first updating module, the first filtering module and the first reducing module can all be realized in the DSP of the receiving end.
  • the first condition further includes: the absolute value of the real part is smaller than a first threshold. Since the absolute value of the real part of the spectral estimation coefficient is positively correlated with the ability of the receiving end to eliminate the second impact, when the absolute value of the real part of the spectral estimation coefficient is smaller than the first threshold, it means that the second impact is relatively small. At this time, reducing the update frequency of the real part of the spectral estimation coefficient will reduce the ability of the receiving end to eliminate the second impact, but it can ensure that the service signal filtered by the receiving end is less affected by the second impact.
  • the communication device includes: a second updating module (not shown in FIG. 14 ), a second filtering module (not shown in FIG. 14 out) and a second lowering module (not shown in Figure 14).
  • the second updating module is configured to update the imaginary part of the spectral estimation coefficient according to the second frequency after acquiring the spectral estimation coefficient of the service signal, so as to update the spectral estimation coefficient;
  • the second filtering module is configured to update the spectral estimation coefficient according to the second frequency
  • the current spectrum estimation coefficient is used to filter the service signal;
  • the second reducing module is configured to reduce the second frequency when the second condition is met.
  • the second condition includes: the receiving end sends the frequency offset parameter to the sending end.
  • the second condition includes: the receiving end sends the spectrum information to the sending end.
  • the second updating module, the second filtering module and the second reducing module can be realized by means of software and/or hardware, for example, the second updating module, the second filtering module and the second reducing module can all be realized in the DSP of the receiving end.
  • the receiving end in the receiving end filters the service signal according to the spectral estimation coefficient
  • the imaginary part in the spectral estimation coefficient is related to eliminating the first impact on the service signal.
  • the sending end can adjust the center frequency of the sending end according to the received information, so that the service signal The frequency offset is corrected to a certain extent.
  • the imaginary part in the spectral estimation coefficient will become smaller, and the update frequency of the imaginary part in the spectral estimation coefficient (the above-mentioned second frequency) will be reduced.
  • the ability of the receiving end to eliminate the first influence will be reduced, due to the degree of frequency offset of the service signal has been reduced, so the degree of frequency deviation of the service signal will not be high.
  • the update frequency of the imaginary part in the spectral estimation coefficient is reduced, the power consumption of the receiving end is reduced, and the power consumption of the receiving end is reduced.
  • the second condition above further includes: the absolute value of the imaginary part of the spectral estimation coefficient is smaller than the second threshold. Since the absolute value of the imaginary part of the spectral estimation coefficient is related to the degree of frequency offset of the service signal, when the absolute value of the imaginary part of the spectral estimation coefficient is smaller than the second threshold, it indicates that the frequency deviation of the service signal is relatively small. Although the update frequency of the imaginary part of the spectral estimation coefficient will reduce the ability of the receiving end to eliminate the first impact, it can ensure that the service signal filtered by the receiving end is less affected by the first impact.
  • FIG. 15 is a block diagram of a communication device provided by an embodiment of the present application.
  • the communication device may be, for example, the sending end in the foregoing embodiments.
  • the sending end and the receiving end are connected through an optical fiber, and at least one filter is arranged on the optical fiber.
  • the communication device includes: an acquisition module 1501 and an adjustment module 1502 .
  • An acquisition module 1501 configured to acquire a frequency offset parameter of the service signal, where the frequency offset parameter is used to indicate: the magnitude and direction of the offset of the center frequency of the service signal relative to the center frequency of the at least one filter at least one kind of information; the frequency offset parameter is a parameter determined according to the spectrum information of the service signal;
  • the adjusting module 1502 is configured to adjust the center frequency of the transmitting end according to the at least one kind of information indicated by the frequency offset parameter. For the operations performed by the adjustment module 1502, reference may be made to the content related to the sending end in S105 above.
  • the acquisition module can acquire the frequency offset parameter, and the frequency offset parameter is used to indicate the offset of the center frequency of the service signal relative to the center frequency of at least one filter connected in series on the optical fiber and At least one information in the offset direction.
  • the adjusting module can adjust the center frequency of the transmitting end according to the at least one kind of information indicated by the frequency offset parameter. In this way, the frequency offset of the service signal is corrected, thereby reducing the ISI of the service signal and reducing the filtering cost of the filter for the service signal.
  • the communication effect between the sending end and the receiving end is guaranteed, so that the service signal between the sending end and the receiving end can be transmitted over a long distance.
  • the adjustment module 1502 can adjust the operating frequency of the laser in the sending end (and/or , the frequency of the digital signal in the sending end), so as to realize the adjustment of the center frequency of the sending end.
  • the center frequencies of signals (such as service signals and non-service signals) sent by the sending end are adjusted, so that the frequency offset of the service signal can be corrected.
  • the acquisition module and the adjustment module can be realized by means of software and/or hardware.
  • both the acquisition module and the adjusting module can be implemented in the DSP module of the sending end.
  • both the acquisition module and the adjusting module can be implemented in the laser at the sending end.
  • some functions of the acquisition module and the adjustment module may also be implemented on the processor at the sending end.
  • the acquiring module 1501 acquires frequency offset parameters in various manners.
  • the acquiring module 1501 may receive the frequency offset parameter sent by the receiving end.
  • the frequency offset parameter may be determined by the receiving end according to the spectrum information of the service signal.
  • the sending end may use the sending module to send the above service signal to the sending end.
  • the communication device further includes a receiving module (not shown in FIG. 15 ) and a pre-compensation module (not shown in FIG. 15 ), the receiving module can be used to receive the spectrum information sent by the receiving end, The precompensation module can be used to perform precompensation on subsequent service signals to be sent according to the spectrum information.
  • the receiving end may send the spectrum information to the sending end.
  • the impact on the service signal during the transmission process includes: the first impact of the filter on the service signal filtering due to the frequency offset of the service signal, and the second impact other than the first impact (such as on the sending end and the receiving end)
  • the influence of optoelectronic devices on the filtering of service signals, and the influence of filters on the filtering of service signals when the service signal is not frequency offset When the frequency offset degree of the service signal is less than the frequency offset degree threshold value, the first impact can be ignored, and at this time, the spectrum information mainly reflects the above-mentioned second impact.
  • the receiving end can feed back the spectrum information of the service signal to the transmitting end, so that the transmitting end can pre-compensate the service signal according to the spectrum information, so as to eliminate the above-mentioned second influence, further reducing the filtering cost.
  • the acquiring module 1501 may receive spectrum information of the service signal sent by the receiving end, and determine the frequency offset parameter according to the spectrum information. At this time, before the sending end receives the spectrum information sent by the receiving end, the sending end may use a sending module (not shown in FIG. 15 ) to send the above service signal to the sending end.
  • the process of determining the frequency offset parameter by the acquisition module according to the spectrum information can refer to the process of the receiving end determining the frequency offset parameter according to the spectrum information, and this application will not repeat it here.
  • the foregoing frequency offset parameter may be used to indicate at least one parameter of an offset magnitude and an offset direction.
  • the acquisition module needs to determine this parameter in other ways.
  • the acquisition module 1501 can determine the adjustment direction of the center frequency of the transmitting end according to the offset direction, and the acquisition module 1501 can also acquire The adjustment amount of the center frequency of the sending end.
  • the adjustment amount can be pre-configured in the acquisition module, or randomly generated by the acquisition module, or sent to the acquisition module by other devices, which is not limited in this application.
  • the obtaining module 1501 may use the size of the offset as the adjustment value of the central frequency of the transmitting end, and the obtaining module 1501
  • the adjustment direction of the center frequency of the sending end can also be obtained.
  • the adjustment direction may be pre-configured in the obtaining module 1501, or randomly generated by the obtaining module 1501, or sent to the obtaining module 1501 by other devices, which is not limited in this application.
  • the acquisition module 1501 can acquire the frequency offset parameter again (such as receiving the frequency offset parameter sent by the transmitter), and judge whether the offset value indicated by the frequency offset parameter is decrease.
  • the adjusting module 1502 adjusts the center frequency of the transmitting end in the correct direction, and the center frequency of the transmitting end can be continuously adjusted in this direction. If the offset indicated by the frequency offset parameter increases, it means that the adjustment direction of the center frequency of the transmitter by the adjustment module 1502 is wrong, and the subsequent adjustment module 1502 can change the adjustment direction of its center frequency to adjust the transmission in the opposite direction. end center frequency.
  • the adjustment module 1502 may judge whether the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold before adjusting the center frequency of the transmitting end, and only when it is determined that the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold Adjust the center frequency of the sender. When the frequency deviation degree of the service signal is less than or equal to the frequency deviation degree threshold, the adjustment module 1502 does not need to adjust its center frequency.
  • the adjustment module 1502 to judge whether the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold, and the following two implementation ways will be taken as examples to explain.
  • the frequency offset parameter is used to indicate the size of the above-mentioned offset.
  • the adjustment module 1502 judges whether the degree of frequency offset is greater than the threshold of the frequency offset. You can refer to the judgment of the receiving end according to the size of the offset. The process of whether the frequency offset degree is greater than the frequency offset degree threshold is not described here in this application.
  • the frequency offset parameter (or spectrum information) sent by the receiving end includes the imaginary part of the spectrum estimation coefficient.
  • the adjustment module 1502 can judge whether the frequency offset degree of the service signal is greater than the frequency offset degree threshold according to the imaginary part of the spectral estimation coefficient.
  • the process of the adjustment module 1502 judging whether the frequency offset degree is greater than the frequency offset degree threshold according to the imaginary part of the spectral estimation coefficient can refer to the process of the receiving end judging whether the frequency offset degree is greater than the frequency offset degree threshold according to the imaginary part of the spectral estimation coefficient. This will not be repeated.
  • both the sending end and the receiving end judge whether the frequency deviation degree of the service signal is greater than the frequency deviation degree threshold, the accuracy of the judgment result is improved through the double judgment of the sending end and the receiving end.
  • the embodiment of the present application also provides a communication system, and the communication system includes: a sending end and a receiving end.
  • the sending end includes any communication device for the sending end provided by the embodiments of the present application (such as the communication device shown in FIG. 14 );
  • the receiving end includes any communication device for the receiving end provided by the embodiments of the application (such as communication device shown in Figure 15).
  • first and second etc. are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.
  • at least one means one or more, and “plurality” means two or more, unless otherwise clearly defined.
  • the term “and/or” is just an association relationship describing associated objects, which means that there can be three relationships, for example, A and/or B can mean: A exists alone, A and B exist at the same time, and B exists alone. three conditions.
  • the disclosed systems and devices may be implemented in other configurations.
  • the device embodiments described above are only illustrative.
  • the division of modules is only a logical function division. In actual implementation, there may be other division methods.
  • multiple modules can be combined or integrated into another A system, or some feature, can be ignored, or not implemented.
  • a unit described as a separate component may or may not be physically separated, and a component described as a unit may or may not be a physical unit, and may be located in one place or distributed over multiple devices. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

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Abstract

一种通信方法、装置及系统，属于通信技术领域。该方法用于接收端，接收端和发送端之间的光纤上设置有至少一个滤波器。该方法包括：接收端在接收发送端发送的业务信号之后，获取业务信号的频谱信息，并根据频谱信息，向发送端发送业务信号的频偏参数；其中，频偏参数用于指示：业务信号的中心频率相对该至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。在这种情况下，发送端可以在接收接收端发送的频偏参数后，根据该频偏参数调节发送端的中心频率。本申请解决了发送端和接收端之间的通信效果较差的问题，本申请用于发送端的中心频率的校正。

Description

通信方法、装置及系统
本申请要求于2021年7月28日提交的、申请号为202110859534.X、申请名称为“通信方法、装置及系统”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，特别涉及一种通信方法、装置及系统。
背景技术
随着通信技术的发展，通信装置越来越多的进入人们的生产和生活中。通信装置之间可以传输业务信号，其中，发送业务信号的通信装置称为发送端，接收业务信号的通信装置称为接收端。
发送端和接收端通常通过光纤连接，光纤上设置有滤波器，如波长选择开关(Wavelength Selective Switch，WSS)。发送端向接收端发出的业务信号会经过WSS进行滤波，之后再传输至接收端。
但是，业务信号的中心频率与WSS的中心频率往往存在偏移，WSS对业务信号进行滤波时会滤除业务信号中较多有用的信号，从而影响发送端和接收端之间的通信效果。
发明内容
本申请提供了一种通信方法、装置及系统，可以解决发送端和接收端之间的通信效果较差的问题，所述技术方案如下：
第一方面，提供了一种通信方法，该方法用于接收端，所述接收端与发送端通过光纤连接，所述光纤上设置有至少一个滤波器，所述方法包括：接收端在接收所述发送端发送的业务信号之后，获取所述业务信号的频谱信息，并根据所述频谱信息，向所述发送端发送所述业务信号的频偏参数；其中，所述频偏参数用于指示：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。在这种情况下，发送端可以在接收接收端发送的频偏参数后，根据该频偏参数调节发送端的中心频率。
在本申请实施例提供的通信方法中，接收端能够向发送端发送频偏参数，且频偏参数用于指示业务信号的中心频率相对光纤上串联的至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。所以，发送端可以根据该频偏参数指示的该至少一种信息调节发送端的中心频率。这样一来，便实现了对业务信号的频偏进行校正，进而降低了业务信号的ISI，降低了滤波器对业务信号的滤波代价。保证了发送端和接收端之间的通信效果，使得发送端和接收端之间的业务信号能够长距离传输。
第二方面，提供了一种通信方法，该方法用于接收端，所述接收端与发送端通过光纤连接，所述光纤上设置有至少一个滤波器，所述方法包括：接收端在接收所述发送端发送的业务信号之后，获取所述业务信号的频谱信息，并向所述发送端发送所述频谱信息。在这种情况下，发送端可以在接收接收端发送的业务信号的频谱信息后，根据该频谱信息确定上述频 偏参数，进而根据该频偏参数调节发送端的中心频率。
在本申请实施例提供的通信方法中，接收端能够向发送端发送频谱信息，以便于发送端根据该频谱信息确定频偏参数，且频偏参数用于指示业务信号的中心频率相对光纤上串联的至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。之后，发送端可以根据该频偏参数指示的该至少一种信息调节发送端的中心频率。这样一来，便实现了对业务信号的频偏进行校正，进而降低了业务信号的ISI，降低了滤波器对业务信号的滤波代价。保证了发送端和接收端之间的通信效果，使得发送端和接收端之间的业务信号能够长距离传输。
在上述第一方面和第二方面中，上述业务信号的频谱信息可以是指业务信号的信号谱和/或噪声谱的信息，其中，噪声谱能指示噪声对业务信号的影响。业务信号在从发送端传输至接收端的过程中，会受到噪声的影响，频谱信息能够指示噪声对业务信号的影响。
示例地，在上述第一方面和第二方面中，业务信号的频谱信息包括业务信号的信道响应或谱估计系数。信道响应和谱估计系数均能够反映业务信号的信号谱和/或噪声谱的信息。
一方面，在频谱信息包括信道响应的情况下，在上述第一方面和第二方面中，接收端可以对所述信道响应进行快速傅立叶变换，得到频域响应，并根据所述频域响应和所述业务信号的波特率，得到所述频偏参数。
示例地，所述信道响应包括N个采样点，N表示所述快速傅里叶变换的点数；所述频域响应包括所述业务信号在N个频率下的功率，且所述N个采样点与所述N个频率一一对应，所述业务信号在每个所述频率下的功率经过对应的采样点变换得到；接收端在根据所述频域响应和所述业务信号的波特率，得到所述频偏参数时，可以根据频偏公式，得到所述频偏参数；其中，所述频偏公式包括：f＝(N/2-M)*F/N；f表示所述频偏参数；M表示功率最小的所述频率对应的采样点的索引；F表示所述业务信号的波特率。
另一方面，在频谱信息包括谱估计系数的情况下，在上述第一方面和第二方面中，接收端可以根据所述频谱信息确定所述谱估计系数的虚部，并根据所述谱估计系数的虚部的正负确定所述频偏参数。此时，频偏参数指示的上述至少一种信息包括所述偏移方向。
又一方面，在频谱信息包括谱估计系数的情况下，在上述第一方面和第二方面中，接收端可以根据所述频谱信息确定所述谱估计系数的虚部，并根据所述谱估计系数的虚部确定所述频偏参数。此时，频偏参数指示的所述至少一种信息包括所述偏移方向，所述频偏参数还用于指示所述谱估计系数的虚部的绝对值。
可选地，在上述第一方面中，接收端在向所述发送端发送所述业务信号的频偏参数之前，可以确定所述业务信号的频偏程度大于频偏程度阈值。在上述第二方面中，接收端在向所述发送端发送所述业务信号的频谱信息之前，也可以确定所述业务信号的频偏程度大于频偏程度阈值。其中，所述业务信号的频偏程度为：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的频偏程度。在业务信号的频偏程度大于频偏程度阈值时，接收端可以确定当前业务信号的频偏程度较高，此时接收端可以向所述发送端发送第一方面中的频偏参数或第二方面中的频谱信息，以便于发送端根据接收到的信息调节其中心频率，从而对业务信号的频偏进行校正。在业务信号的频偏程度小于或等于频偏程度阈值时，接收端可以确定当前业务信号的频偏程度较低，此时无需对业务信号的频偏进行校正，因此，接收端无需向所述发送端发送第一方面中的频偏参数或第二方面中的频谱信息。
在上述第一方面和第二方面中，接收端判断业务信号的频偏程度是否大于频偏程度阈值 的方式多种多样，以下将以其中的两种可实现方式为例进行讲解。
在第一种可实现方式中，接收端会根据频谱信息确定频偏参数，且频偏参数指示的至少一种信息包括所述偏移量大小。此时，接收端可以在所述偏移量大小大于偏移量大小阈值时，确定所述业务信号的频偏程度大于频偏程度阈值。
在第二种可实现方式中，频谱信息是业务信号的谱估计系数，此时，接收端可以在谱估计系数的虚部的绝对值大于绝对值阈值时，确定业务信号的频偏程度大于频偏程度阈值；在谱估计系数的虚部的绝对值小于或等于绝对值阈值时，确定业务信号的频偏程度小于或等于频偏程度阈值。
可选地，在上述第一方面和第二方面中，接收端在获取所述业务信号的频谱信息时，可以首先对所述业务信号进行均衡处理；之后，再根据所述均衡处理后的所述业务信号，获取所述频谱信息。接收端对业务信号进行均衡处理能够消除业务信号受到的环境因素(如光纤摆动、打雷或闪电等)影响，提升获取到的频谱信息的准确度。
可选地，在上述第一方面中，所述方法还包括：接收端在所述业务信号的频偏程度小于或等于频偏程度阈值时，向所述发送端发送所述频谱信息。发送端可以根据该频谱信息对业务信号进行预补偿。需要说明的是，业务信号在传输过程中受到的影响包括：由于业务信号频偏所带来的滤波器对业务信号滤波的第一影响，以及除第一影响之外的第二影响(如发送端和接收端上光电器件对业务信号滤波带来的影响，以及在业务信号未频偏时滤波器对业务信号滤波所带来的影响)。在业务信号的频偏程度小于频偏程度阈值时，第一影响可以忽略不计，此时频谱信息主要反映上述第二影响。因此，在业务信号的频偏程度小于频偏程度阈值时，接收端可以将业务信号的频谱信息反馈给发送端，以便于发送端根据该频谱信息对业务信号进行预补偿，以消除上述第二影响，进一步降低滤波代价。
可选地，在上述第一方面中，所述方法包括：接收端在获取所述业务信号的谱估计系数后，根据第一频率更新所述谱估计系数中的实部，以更新所述谱估计系数；之后，接收端根据当前的所述谱估计系数，对所述业务信号进行滤波。在第一条件满足时，接收端可以降低所述第一频率，所述第一条件包括：所述接收端向所述发送端发送所述频谱信息。换句话说，在接收端向发送端发送用于预补偿的频谱信息之后，接收端可以将第一频率降低。需要说明的是，接收端在根据谱估计系数对业务信号进行滤波时，谱估计系数中的实部与消除业务信号受到的第二影响相关。谱估计系数中实部的更新频率(上述第一频率)越大，接收端在根据谱估计系数对业务信号进行滤波对第二影响的消除能力越高。本申请实施例中，在接收端向发送端发送用于预补偿的频谱信息后，发送端可以根据该频谱信息对业务信号进行预补偿，以降低或消除第二影响。此时，谱估计系数中实部会变小，降低谱估计系数中实部的更新频率(上述第一频率)，虽然会降低接收端对第二影响的消除能力，但由于业务信号在发送端已经进行了预补偿，所以，第二影响不会较高。并且，由于降低了谱估计系数中实部的更新频率，因此，降低了接收端的功耗。
可选地，所述第一条件还包括：所述实部的绝对值小于第一阈值。由于谱估计系数的实部的绝对值的大小与接收端对第二影响的消除能力正相关，在谱估计系数的实部的绝对值小于第一阈值时，说明第二影响较小。此时降低谱估计系数中实部的更新频率，虽然会降低接收端对第二影响的消除能力，但能够保证经过接收端滤波之后的业务信号受到的第二影响较小。
可选地，在上述第一方面和第二方面中，所述方法包括：接收端在获取所述业务信号的谱估计系数后，根据第二频率更新所述谱估计系数中的虚部，以更新所述谱估计系数；之后，接收端根据当前的所述谱估计系数，对所述业务信号进行滤波；在第二条件满足时，接收端可以降低所述第二频率。在上述第一方面中，所述第二条件包括：所述接收端向所述发送端发送所述频偏参数。在上述第二方面中，所述第二条件包括：所述接收端向所述发送端发送所述频谱信息。
需要说明的是，接收端中的接收端在根据谱估计系数对业务信号进行滤波时，谱估计系数中的虚部与消除业务信号受到的第一影响相关。谱估计系数中虚部的更新频率(上述第二频率)越大，接收端对第一影响的消除能力越高。
在接收端向发送端发送第一方面中的频偏参数或第二方面中的频谱信息之后，发送端可以根据接收到的信息调节发送端的中心频率，从而对业务信号的频偏进行一定的校正。此时，谱估计系数中虚部会变小，降低谱估计系数中虚部的更新频率(上述第二频率)，虽然会降低接收端对第一影响的消除能力，但由于业务信号的频偏程度已经降低，所以，业务信号的频偏程度不会较高。并且，由于降低了谱估计系数中虚部的更新频率，因此，降低了接收端的功耗，降低了接收端的功耗。
可选地，上述第二条件还包括：谱估计系数的虚部的绝对值小于第二阈值。由于谱估计系数的虚部的绝对值的大小与业务信号的频偏程度相关，在谱估计系数的虚部的绝对值小于第二阈值时，说明业务信号的频偏程度较小，此时降低谱估计系数中虚部的更新频率，虽然会降低接收端对第一影响的消除能力，但能够保证经过接收端滤波之后的业务信号受到的第一影响较小。
第三方面，提供了一种通信方法，该方法可以用于发送端，所述发送端与接收端通过光纤连接，所述光纤上设置有至少一个滤波器，所述方法包括：发送端在获取业务信号的频偏参数后，根据所述频偏参数所指示的至少一种信息，调节所述发送端的中心频率。其中，所述频偏参数用于指示的所述至少一种信息为：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息；所述频偏参数是根据所述业务信号的频谱信息确定的参数。
在本申请实施例提供的通信方法中，发送端能够获取到频偏参数，且频偏参数用于指示业务信号的中心频率相对光纤上串联的至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。并且，发送端可以根据该频偏参数指示的该至少一种信息调节发送端的中心频率。这样一来，便实现了对业务信号的频偏进行校正，进而降低了业务信号的ISI，降低了滤波器对业务信号的滤波代价。保证了发送端和接收端之间的通信效果，使得发送端和接收端之间的业务信号能够长距离传输。
可选地，由于发送端的中心频率与发送端中数字信号的频率和激光器的工作频率均相关，因此发送端在调节发送端的中心频率时，可以调节发送端中激光器的工作频率(和/或，发送端中数字信号的频率)，从而实现对发送端的中心频率的调节。在发送端的中心频率被调节后，发送端发出的信号(如业务信号和非业务信号)的中心频率被调节，从而能够实现对业务信号的频偏的校正。
发送端获取频偏参数的方式多种多样。
在发送端获取频偏参数的第一种可选方式中，发送端可以接收接收端发送的频偏参数。 此时，频偏参数可以由接收端根据业务信号的频谱信息确定。并且，发送端在接收接收端发送的频偏参数之前，还可以向发送端发送上述业务信号。
在该第一种可选方式中，发送端还可以接收接收端发送的频谱信息，此时，发送端还可以根据该频谱信息对后续待发送的业务信号进行预补偿。
需要说明的是，接收端可以在所述业务信号的频偏程度小于或等于频偏程度阈值时，向所述发送端发送所述频谱信息。业务信号在传输过程中受到的影响包括：由于业务信号频偏所带来的滤波器对业务信号滤波的第一影响，以及除第一影响之外的第二影响(如发送端和接收端上光电器件对业务信号滤波带来的影响，以及在业务信号未频偏时滤波器对业务信号滤波所带来的影响)。在业务信号的频偏程度小于频偏程度阈值时，第一影响可以忽略不计，此时频谱信息主要反映上述第二影响。因此，在业务信号的频偏程度小于频偏程度阈值时，接收端可以将业务信号的频谱信息反馈给发送端，以便于发送端根据该频谱信息对业务信号进行预补偿，以消除上述第二影响，进一步降低滤波代价。
在发送端获取频偏参数的第二种可选方式中，发送端可以接收接收端发送的业务信号的频谱信息，并根据该频谱信息确定该频偏参数。此时，发送端在接收接收端发送的频谱信息之前，还可以向发送端发送上述业务信号。发送端根据频谱信息确定该频偏参数的过程可以参考上述第一方面中接收端根据频谱信息确定频偏参数的过程，本申请在此不做赘述。
上述频偏参数可以用于指示偏移量大小和偏移方向中的至少一种参数。当频偏参数未能指示偏移量大小和偏移方向中的一种参数时，发送端需要采用其他方式确定这种参数。
示例地，在频偏参数用于指示该偏移方向，且不用于指示偏移量大小时，发送端可以根据该偏移方向确定发送端的中心频率的调节方向，并且发送端还可以获取发送端的中心频率的调节量大小。该调节量大小可以预先配置在发送端中，也可以由发送端随机生成，也可以由其他设备发送给发送端，本申请对此不作限定。
又示例地，在频偏参数用于指示该偏移量大小，且不用于指示偏移方向时，发送端可以将该偏移量大小作为发送端的中心频率的调节量大小，并且发送端还可以获取发送端的中心频率的调节方向。该调节方向可以预先配置在发送端中，也可以由发送端随机生成，也可以由其他设备发送给发送端，本申请对此不作限定。并且，在发送端每次调节发送端的中心频率之后，发送端可以再次获取频偏参数(如接收发送端发送的频偏参数)，并判断该频偏参数所指示的偏移量大小是否减小。如果频偏参数所指示的偏移量大小减小，说明发送端对其的中心频率的调节方向是正确的，后续可以继续向该调节方向调节发送端的中心频率。如果频偏参数所指示的偏移量大小增大，说明发送端对其中心频率的调节方向是错误的，后续发送端可以改变其中心频率的调节方向，以向相反的方向调节发送端的中心频率。
可选地，发送端可以在调节其中心频率之前，对业务信号的频偏程度是否大于频偏程度阈值进行判断，并在确定业务信号的频偏程度大于频偏程度阈值时，才调节发送端的中心频率。在业务信号的频偏程度小于或等于频偏程度阈值时，发送端无需对其中心频率进行调节。
发送端对业务信号的频偏程度是否大于频偏程度阈值进行判断的方式多种多样，以下将以其中的两种可实现方式为例进行讲解。
在第一种可实现方式中，发送端获取的频偏参数用于指示上述偏移量大小，此时，发送端判断频偏程度是否大于频偏程度阈值的过程，可以参考接收端根据偏移量大小判断频偏程度是否大于频偏程度阈值的过程，本申请在此不作赘述。
在第二种可实现方式中，接收端发送的频偏参数(或频谱信息)包括谱估计系数的虚部。发送端可以根据谱估计系数的虚部对业务信号的频偏程度是否大于频偏程度阈值进行判断。发送端根据谱估计系数的虚部判断频偏程度是否大于频偏程度阈值的过程，可以参考接收端根据谱估计系数的虚部判断频偏程度是否大于频偏程度阈值的过程，本申请在此不作赘述。
在发送端和接收端均对业务信号的频偏程度是否大于频偏程度阈值进行判断时，通过发送端和接收端的双重判断，提升了判断结果的准确度。
第四方面，提供了一种通信装置，用于接收端，所述接收端与发送端通过光纤连接，所述光纤上设置有至少一个滤波器，所述通信装置包括：接收模块、获取模块和第一发送模块。其中，接收模块用于接收所述发送端发送的业务信号；获取模块用于获取所述业务信号的频谱信息；第一发送模块用于根据所述频谱信息，向所述发送端发送所述业务信号的频偏参数；所述频偏参数用于指示：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。
在本申请实施例提供的通信装置中，第一发送模块能够向发送端发送频偏参数，且频偏参数用于指示业务信号的中心频率相对光纤上串联的至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。所以，发送端可以根据该频偏参数指示的该至少一种信息调节发送端的中心频率。这样一来，便实现了对业务信号的频偏进行校正，进而降低了业务信号的ISI，降低了滤波器对业务信号的滤波代价。保证了发送端和接收端之间的通信效果，使得发送端和接收端之间的业务信号能够长距离传输。
第五方面，提供了一种通信装置，该通信装置用于接收端，所述接收端与发送端通过光纤连接，所述光纤上设置有至少一个滤波器，所述通信装置包括：接收模块、获取模块和第一发送模块。其中，接收模块用于接收所述发送端发送的业务信号，获取模块用于获取所述业务信号的频谱信息，第一发送模块用于向所述发送端发送所述频谱信息。在这种情况下，发送端可以在接收接收端发送的业务信号的频谱信息后，根据该频谱信息确定上述频偏参数，进而根据该频偏参数调节发送端的中心频率。
在本申请实施例提供的通信装置中，第一发送模块能够向发送端发送频谱信息，以便于发送端根据该频谱信息确定频偏参数，且频偏参数用于指示业务信号的中心频率相对光纤上串联的至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。之后，发送端可以根据该频偏参数指示的该至少一种信息调节发送端的中心频率。这样一来，便实现了对业务信号的频偏进行校正，进而降低了业务信号的ISI，降低了滤波器对业务信号的滤波代价。保证了发送端和接收端之间的通信效果，使得发送端和接收端之间的业务信号能够长距离传输。
在上述第四方面和第五方面中，上述业务信号的频谱信息可以是指业务信号的信号谱和/或噪声谱的信息，其中，噪声谱能指示噪声对业务信号的影响。业务信号在从发送端传输至接收端的过程中，会受到噪声的影响，频谱信息能够指示噪声对业务信号的影响。
示例地，在上述第四方面和第五方面中，业务信号的频谱信息包括业务信号的信道响应或谱估计系数。信道响应和谱估计系数均能够反映业务信号的信号谱和/或噪声谱的信息。
一方面，在频谱信息包括信道响应的情况下，上述第四方面和第五方面中的所述通信装置还包括：第一处理模块和第二处理模块，第一处理模块，用于对所述信道响应进行快速傅立叶变换，得到频域响应；第二处理模块，用于根据所述频域响应和所述业务信号的波特率， 得到所述频偏参数。
示例地，所述信道响应包括N个采样点，N表示所述快速傅里叶变换的点数；所述频域响应包括所述业务信号在N个频率下的功率，且所述N个采样点与所述N个频率一一对应，所述业务信号在每个所述频率下的功率经过对应的采样点变换得到；所述第二处理模块用于：根据频偏公式，得到所述频偏参数；其中，所述频偏公式包括：f＝(N/2-M)*F/N；f表示所述频偏参数；M表示功率最小的所述频率对应的采样点的索引；F表示所述业务信号的波特率。
另一方面，在频谱信息包括谱估计系数的情况下，上述第四方面和第五方面中的所述通信装置还包括：第一确定模块和第二确定模块。第一确定模块，用于根据所述频谱信息确定所述谱估计系数的虚部；第二确定模块，用于根据所述谱估计系数的虚部的正负确定所述频偏参数，所述至少一种信息包括所述偏移方向。
又一方面，在频谱信息包括谱估计系数的情况下，上述第四方面和第五方面中的所述通信装置还包括：第三确定模块和第四确定模块。第三确定模块，用于根据所述频谱信息确定所述谱估计系数的虚部；第四确定模块，用于根据所述谱估计系数的虚部确定所述频偏参数，所述至少一种信息包括所述偏移方向，所述频偏参数还用于指示所述谱估计系数的虚部的绝对值。
可选地，在上述第四方面中，接收端在向所述发送端发送所述业务信号的频偏参数之前，还可以利用第五确定模块确定所述业务信号的频偏程度大于频偏程度阈值。在上述第五方面中，接收端在向所述发送端发送所述业务信号的频谱信息之前，也可以利用第五确定模块确定所述业务信号的频偏程度大于频偏程度阈值。其中，所述业务信号的频偏程度为：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的频偏程度。在业务信号的频偏程度大于频偏程度阈值时，接收端可以确定当前业务信号的频偏程度较高，此时接收端可以向所述发送端发送第四方面中的频偏参数或第五方面中的频谱信息，以便于发送端根据接收到的信息调节其中心频率，从而对业务信号的频偏进行校正。在业务信号的频偏程度小于或等于频偏程度阈值时，接收端可以确定当前业务信号的频偏程度较低，此时无需对业务信号的频偏进行校正，因此，接收端无需向所述发送端发送第四方面中的频偏参数或第五方面中的频谱信息。
在上述第四方面和第五方面中，接收端判断业务信号的频偏程度是否大于频偏程度阈值的方式多种多样，以下将以其中的两种可实现方式为例进行讲解。
在第一种可实现方式中，第五确定模块会根据频谱信息确定频偏参数，且频偏参数指示的至少一种信息包括所述偏移量大小。此时，接收端可以在所述偏移量大小大于偏移量大小阈值时，确定所述业务信号的频偏程度大于频偏程度阈值。
在第二种可实现方式中，频谱信息是业务信号的谱估计系数，此时，接收端可以在谱估计系数的虚部的绝对值大于绝对值阈值时，可以利用第六确定模块确定业务信号的频偏程度大于频偏程度阈值；在谱估计系数的虚部的绝对值小于或等于绝对值阈值时，确定业务信号的频偏程度小于或等于频偏程度阈值。
可选地，在上述第四方面和第五方面中，获取模块在获取所述业务信号的频谱信息时，可以首先对所述业务信号进行均衡处理；之后，再根据所述均衡处理后的所述业务信号，获取所述频谱信息。接收端对业务信号进行均衡处理能够消除业务信号受到的环境因素(如光 纤摆动、打雷或闪电等)影响，提升获取到的频谱信息的准确度。
可选地，在上述第四方面中，所述通信装置还包括：第二发送模块，用于在所述业务信号的频偏程度小于或等于频偏程度阈值时，向所述发送端发送所述频谱信息。发送端可以根据该频谱信息对业务信号进行预补偿。需要说明的是，业务信号在传输过程中受到的影响包括：由于业务信号频偏所带来的滤波器对业务信号滤波的第一影响，以及除第一影响之外的第二影响(如发送端和接收端上光电器件对业务信号滤波带来的影响，以及在业务信号未频偏时滤波器对业务信号滤波所带来的影响)。在业务信号的频偏程度小于频偏程度阈值时，第一影响可以忽略不计，此时频谱信息主要反映上述第二影响。因此，在业务信号的频偏程度小于频偏程度阈值时，接收端可以将业务信号的频谱信息反馈给发送端，以便于发送端根据该频谱信息对业务信号进行预补偿，以消除上述第二影响，进一步降低滤波代价。
可选地，在上述第四方面中，所述通信装置包括：第一更新模块、第一滤波模块和第一降低模块。其中，第一更新模块，用于在获取所述业务信号的谱估计系数后，根据第一频率更新所述谱估计系数中的实部，以更新所述谱估计系数；第一滤波模块，用于根据当前的所述谱估计系数，对所述业务信号进行滤波；第一降低模块，用于在第一条件满足时，降低所述第一频率，所述第一条件包括：所述接收端向所述发送端发送所述频谱信息。换句话说，在接收端向发送端发送用于预补偿的频谱信息之后，接收端可以将第一频率降低。需要说明的是，接收端在根据谱估计系数对业务信号进行滤波时，谱估计系数中的实部与消除业务信号受到的第二影响相关。谱估计系数中实部的更新频率(上述第一频率)越大，接收端在根据谱估计系数对业务信号进行滤波对第二影响的消除能力越高。本申请实施例中，在接收端向发送端发送用于预补偿的频谱信息后，发送端可以根据该频谱信息对业务信号进行预补偿，以降低或消除第二影响。此时，谱估计系数中实部会变小，降低谱估计系数中实部的更新频率(上述第一频率)，虽然会降低接收端对第二影响的消除能力，但由于业务信号在发送端已经进行了预补偿，所以，第二影响不会较高。并且，由于降低了谱估计系数中实部的更新频率，因此，降低了接收端的功耗。
可选地，所述第一条件还包括：所述实部的绝对值小于第一阈值。由于谱估计系数的实部的绝对值的大小与接收端对第二影响的消除能力正相关，在谱估计系数的实部的绝对值小于第一阈值时，说明第二影响较小。此时降低谱估计系数中实部的更新频率，虽然会降低接收端对第二影响的消除能力，但能够保证经过接收端滤波之后的业务信号受到的第二影响较小。
可选地，在上述第四方面和第五方面中，所述通信装置包括：第二更新模块、第二滤波模块和第二降低模块。第二更新模块，用于在获取所述业务信号的谱估计系数后，根据第二频率更新所述谱估计系数中的虚部，以更新所述谱估计系数；第二滤波模块，用于根据当前的所述谱估计系数，对所述业务信号进行滤波；第二降低模块，用于在第二条件满足时，降低所述第二频率。在上述第四方面中，所述第二条件包括：所述接收端向所述发送端发送所述频偏参数。在上述第五方面中，所述第二条件包括：所述接收端向所述发送端发送所述频谱信息。
需要说明的是，接收端中的接收端在根据谱估计系数对业务信号进行滤波时，谱估计系数中的虚部与消除业务信号受到的第一影响相关。谱估计系数中虚部的更新频率(上述第二频率)越大，接收端对第一影响的消除能力越高。
在接收端向发送端发送第四方面中的频偏参数或第五方面中的频谱信息之后，发送端可以根据接收到的信息调节发送端的中心频率，从而对业务信号的频偏进行一定的校正。此时，谱估计系数中虚部会变小，降低谱估计系数中虚部的更新频率(上述第二频率)，虽然会降低接收端对第一影响的消除能力，但由于业务信号的频偏程度已经降低，所以，业务信号的频偏程度不会较高。并且，由于降低了谱估计系数中虚部的更新频率，因此，降低了接收端的功耗，降低了接收端的功耗。
可选地，上述第二条件还包括：谱估计系数的虚部的绝对值小于第二阈值。由于谱估计系数的虚部的绝对值的大小与业务信号的频偏程度相关，在谱估计系数的虚部的绝对值小于第二阈值时，说明业务信号的频偏程度较小，此时降低谱估计系数中虚部的更新频率，虽然会降低接收端对第一影响的消除能力，但能够保证经过接收端滤波之后的业务信号受到的第一影响较小。
第六方面，提供了一种通信装置，该通信装置可以用于发送端，所述发送端与接收端通过光纤连接，所述光纤上设置有至少一个滤波器，所述通信装置包括：获取模块和调节模块。其中，获取模块，用于获取业务信号的频偏参数，所述频偏参数用于指示：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息；所述频偏参数是根据所述业务信号的频谱信息确定的参数；调节模块，用于根据所述频偏参数所指示的所述至少一种信息，调节所述发送端的中心频率。
在本申请实施例提供的通信装置中，获取模块能够获取到频偏参数，且频偏参数用于指示业务信号的中心频率相对光纤上串联的至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。并且，调节模块可以根据该频偏参数指示的该至少一种信息调节发送端的中心频率。这样一来，便实现了对业务信号的频偏进行校正，进而降低了业务信号的ISI，降低了滤波器对业务信号的滤波代价。保证了发送端和接收端之间的通信效果，使得发送端和接收端之间的业务信号能够长距离传输。
可选地，由于发送端的中心频率与发送端中数字信号的频率和激光器的工作频率均相关，因此调节模块在调节发送端的中心频率时，可以调节发送端中激光器的工作频率(和/或，发送端中数字信号的频率)，从而实现对发送端的中心频率的调节。在发送端的中心频率被调节后，发送端发出的信号(如业务信号和非业务信号)的中心频率被调节，从而能够实现对业务信号的频偏的校正。
获取模块获取频偏参数的方式多种多样。
在获取模块获取频偏参数的第一种可选方式中，获取模块可以接收接收端发送的频偏参数。此时，频偏参数可以由接收端根据业务信号的频谱信息确定。并且，在获取模块接收接收端发送的频偏参数之前，发送端还可以利用发送模块向发送端发送上述业务信号。
在该第一种可选方式中，通信装置还包括接收模块和预补偿模块，接收模块可以用于接收接收端发送的频谱信息，预补偿模块可以用于根据该频谱信息对后续待发送的业务信号进行预补偿。
需要说明的是，接收端可以在所述业务信号的频偏程度小于或等于频偏程度阈值时，向所述发送端发送所述频谱信息。业务信号在传输过程中受到的影响包括：由于业务信号频偏所带来的滤波器对业务信号滤波的第一影响，以及除第一影响之外的第二影响(如发送端和接收端上光电器件对业务信号滤波带来的影响，以及在业务信号未频偏时滤波器对业务信号 滤波所带来的影响)。在业务信号的频偏程度小于频偏程度阈值时，第一影响可以忽略不计，此时频谱信息主要反映上述第二影响。因此，在业务信号的频偏程度小于频偏程度阈值时，接收端可以将业务信号的频谱信息反馈给发送端，以便于发送端根据该频谱信息对业务信号进行预补偿，以消除上述第二影响，进一步降低滤波代价。
在获取模块获取频偏参数的第二种可选方式中，获取模块可以接收接收端发送的业务信号的频谱信息，并根据该频谱信息确定该频偏参数。此时，发送端在接收接收端发送的频谱信息之前，发送端还可以利用发送模块向发送端发送上述业务信号。获取模块根据频谱信息确定该频偏参数的过程可以参考上述第一方面中接收端根据频谱信息确定频偏参数的过程，本申请在此不做赘述。
上述频偏参数可以用于指示偏移量大小和偏移方向中的至少一种参数。当频偏参数未能指示偏移量大小和偏移方向中的一种参数时，获取模块需要采用其他方式确定这种参数。
示例地，在频偏参数用于指示该偏移方向，且不用于指示偏移量大小时，获取模块可以根据该偏移方向确定发送端的中心频率的调节方向，并且获取模块还可以获取发送端的中心频率的调节量大小。该调节量大小可以预先配置在获取模块中，也可以由获取模块随机生成，也可以由其他设备发送给获取模块，本申请对此不作限定。
又示例地，在频偏参数用于指示该偏移量大小，且不用于指示偏移方向时，获取模块可以将该偏移量大小作为发送端的中心频率的调节量大小，并且获取模块还可以获取发送端的中心频率的调节方向。该调节方向可以预先配置在获取模块中，也可以由获取模块随机生成，也可以由其他设备发送给获取模块，本申请对此不作限定。并且，在调节模块每次调节发送端的中心频率之后，获取模块可以再次获取频偏参数(如接收发送端发送的频偏参数)，并判断该频偏参数所指示的偏移量大小是否减小。如果频偏参数所指示的偏移量大小减小，说明调节模块对发送端的中心频率的调节方向是正确的，后续可以继续向该调节方向调节发送端的中心频率。如果频偏参数所指示的偏移量大小增大，说明调节模块对发送端的中心频率的调节方向是错误的，后续调节模块可以改变其中心频率的调节方向，以向相反的方向调节发送端的中心频率。
可选地，调节模块可以在调节发送端的中心频率之前，可以对业务信号的频偏程度是否大于频偏程度阈值进行判断，并在确定业务信号的频偏程度大于频偏程度阈值时，才调节发送端的中心频率。在业务信号的频偏程度小于或等于频偏程度阈值时，调节模块无需对其中心频率进行调节。
调节模块对业务信号的频偏程度是否大于频偏程度阈值进行判断的方式多种多样，以下将以其中的两种可实现方式为例进行讲解。
在第一种可实现方式中，频偏参数用于指示上述偏移量大小，此时，调节模块判断频偏程度是否大于频偏程度阈值的过程，可以参考接收端根据偏移量大小判断频偏程度是否大于频偏程度阈值的过程，本申请在此不作赘述。
在第二种可实现方式中，接收端发送的频偏参数(或频谱信息)包括谱估计系数的虚部。调节模块可以根据谱估计系数的虚部对业务信号的频偏程度是否大于频偏程度阈值进行判断。调节模块根据谱估计系数的虚部判断频偏程度是否大于频偏程度阈值的过程，可以参考接收端根据谱估计系数的虚部判断频偏程度是否大于频偏程度阈值的过程，本申请在此不作赘述。
在发送端和接收端均对业务信号的频偏程度是否大于频偏程度阈值进行判断时，通过发送端和接收端的双重判断，提升了判断结果的准确度。
第七方面，提供了一种通信系统，该通信系统包括：发送端和接收端。所述发送端包括第四方面或第五方面中任一设计所述的通信装置；所述接收端包括第六方面中任一设计所述的通信装置。
第二方面至第七方面中任一种设计方式所带来的技术效果可参见第一方面中相应设计方式所带来的技术效果，此处不再赘述。
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图1为本申请实施例提供的一种通信系统的结构示意图；
图2为本申请实施例提供的另一种通信系统的结构示意图；
图3为本申请实施例提供的一种业务信号的功率谱和WSS的功率谱的示意图；
图4为本申请实施例提供的另一种业务信号的功率谱和WSS的功率谱的示意图；
图5为本申请实施例提供的又一种业务信号的功率谱和WSS的功率谱的示意图；
图6为本申请实施例提供的一种通信方法的流程图；
图7为本申请实施例提供的一种接收端的功能模块示意图；
图8为本申请实施例提供的一种发送端和接收端的功能模块示意图；
图9为本申请实施例提供的一种业务信号在三种频偏情况下的频域响应的示意图；
图10为本申请实施例提供的另一种业务信号在这三种频偏情况下的频域响应的示意图；
图11为本申请实施例提供的一种谱估计系数中虚部的变化情况的示意图；
图12为本申请实施例提供的另一种谱估计系数中虚部的变化情况的示意图；
图13为本申请实施例提供的又一种谱估计系数中虚部的变化情况的示意图；
图14为本申请实施例提供的一种通信装置的结构示意图；
图15为本申请实施例提供的另一种通信装置的结构示意图。
具体实施方式
为使本申请的原理和技术方案更加清楚，下面将结合附图对本申请实施方式作进一步地详细描述。
图1为本申请实施例提供的一种通信系统的结构示意图，如图1所示，通信系统包括发送端和接收端，并且，发送端和接收端之间通过光纤链路连接。光纤链路包括：光纤，以及设置在光纤上的光中继(如图1中的WSS)。光中继可以包括至少一个滤波器、信号放大器等。并且，当光中继包括多个滤波器时，这些滤波器可以串联在光纤上。上述滤波器为光滤波器，示例性地，光滤波器可以是WSS、梳状滤波器(interleaver，ITL)或者阵列波导光栅(arrayed waveguide grating，AWG)等。图1中以光中继包括1个WSS为例。
示例地，请参考图2，发送端可以包括：电发射机和光发射机。其中，电发射机包括：数字信号调制模块和数模转换模块等。光发射机包括：激光器和光调制器等。数字信号调制模块用于根据需要传输的数据调制数字信号；数模转换模块用于将数字信号转换为模拟信号；激光器用于发出激光；光调制器用于根据模拟信号将激光器发出的激光调制为光信号(如相干光信号或非相干光信号等)，并将光信号发送至光纤。
请继续参考图2，接收端包括：光接收机和电接收机。其中，光接收机包括光探测器等，电接收机包括模数转换模块和信号解调模块。光探测器用于接收光纤上的光信号，并将该光信号转换为模拟信号；模数转换模块用于将该模拟信号转换为数字信号；信号解调模块用于对该数字信号进行解调，得到发送端需要传输的数据。
光纤上传输的光信号包括业务信号。发送端发送的业务信号经过光纤传输和滤波器(如WSS)滤波被接收端接收。其中，滤波器在对业务信号进行滤波时，滤波器允许某一频段的信号通过，并且，禁止该频段之外的信号通过。滤波器所允许通过的信号的频段的中心频率称为滤波器的中心频率。当光纤上设置有多个滤波器时，不同滤波器的中心频率可以相同也可以不同。
目前，业务信号存在频偏，使得滤波器对业务信号进行滤波时往往会滤除业务信号中较多有用的信号，导致滤波器对业务信号的滤波代价较高。其中，业务信号频偏是指：业务信号的中心频率与光纤上设置的至少一个滤波器的中心频率存在偏移。当该至少一个滤波器包括一个滤波器时，该至少一个滤波器的中心频率也即是这一个滤波器的中心频率。当该至少一个滤波器包括多个滤波器时，该至少一个滤波器的中心频率也即是该多个滤波器的级联中心频率。需要说明的是，多个滤波器对信号的滤波效果与具有该级联中心频率的滤波器对该信号的滤波效果相同。
示例地，以滤波器为WSS为例，假设业务信号的功率谱和WSS的功率谱如图3所示。其中，业务信号的功率谱上的每个点对应有一个频率和一个功率，该点表示业务信号在该频率下的功率。WSS的功率谱上的每个点也对应有一个频率和一个功率，WSS允许通过的信号满足一个条件：信号的频率为该功率谱上某一点对应的频率，并且该信号的功率小于该点对应的功率。对于不满足该条件的信号，WSS会进行滤除。当业务信号的中心频率相对WSS的中心频率的偏移情况图3所示时，图3中业务信号的功率谱中位于WSS的功率谱左侧和右侧的部分所表示的信号均会被WSS滤除。
又示例地，请参考图4，当业务信号的中心频率相对WSS的中心频率的偏移情况图4所示时，图4中业务信号的功率谱中位于WSS的功率谱右侧的部分所表示的信号会被WSS滤除。
再示例地，请参考图5，当业务信号的中心频率相对WSS的中心频率的偏移情况图5所示时，图5中业务信号的功率谱中位于WSS的功率谱左侧的部分所表示的信号会被WSS滤除。
另外，在业务信号存在频偏时，业务信号的符号间干扰(Inter Symbol Interference，ISI)会增大，从而影响发送端和接收端之间的通信效果，限制发送端和接收端之间业务信号的长距离传输。
本申请实施例提供了一种通信方法，该方法中的接收端可以向发送端发送频偏参数，且频偏参数用于指示业务信号的中心频率相对光纤上串联的至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。发送端可以根据该频偏参数指示的该至少一种信息调节发送端的中心频率。这样一来，便实现了对业务信号的频偏进行校正，进而降低了业务信号的ISI，降低了滤波器对业务信号的滤波代价。保证了发送端和接收端之间的通信效果，使得发送端和接收端之间的业务信号能够长距离传输。
示例地，图6为本申请实施例提供的一种通信方法的流程图，该方法可以用于本申请实 施例提供的通信系统(如图1或图2所示的通信系统)。如图6所示，该方法包括：
S101、发送端向接收端发送业务信号。
发送端发送的业务信号经过光纤传输和滤波器(如WSS)滤波被接收端接收。
业务信号在传输的过程中可能存在以下两种情况。
一方面，如果业务信号存在频偏，那么业务信号在经过滤波器之后，业务信号中会被滤除一些有用信号，业务信号无法完整的到达接收端。
另一方面，如果业务信号不存在频偏，那么业务信号在经过滤波器之后，业务信号基本不存在会被滤除的有用信号，从而使得业务信号能够比较完整的传输至接收端。
S102、接收端对业务信号进行均衡处理。
接收端在接收到业务信号之后，会对业务信号进行均衡处理(如对业务信号进行偏振相关损伤的补偿、载波恢复、消除部分ISI等处理)，以消除业务信号受到的环境因素(如光纤摆动、打雷或闪电等)影响。接收端可以基于任一种算法对业务信号进行均衡处理。该任一种算法可以是经典的最小二乘法(Least Squares Method，LS)、梯度下降法(如最小均方误差(Least Mean Square，LMS)算法)等。
S103、接收端根据均衡处理后的业务信号，获取业务信号的频谱信息。
业务信号的频谱信息可以是指业务信号的信号谱和/或噪声谱的信息，其中，噪声谱能指示噪声对业务信号的影响。业务信号在从发送端传输至接收端的过程中，会受到噪声的影响，频谱信息能够指示噪声对业务信号的影响。
示例地，业务信号的频谱信息包括业务信号的信道响应或谱估计系数。信道响应和谱估计系数均能够反映业务信号的信号谱和/或噪声谱的信息。
业务信号在从发送端传输至接收端的过程中，会受到信道对业务信号进行滤波的影响，这一影响可以用信道响应来表示。换句话说，业务信号的信道响应用于指示信道滤波对业务信号的影响值。其中，信道滤波包括：光纤上滤波器对业务信号的滤波，以及发送端和接收端中光电器件对业务信号的滤波等。
谱估计是对随机信号序列进行功率谱密度和频谱估计的算法的总称，谱估计包括经典谱估计(不基于系数的非参数谱估计)和现代谱估计(基于系数的参数谱估计)，参数谱估计的系数一般称为谱估计系数。
频谱信息也可以包括除信道响应和谱估计系数之外的其他参数，如信号谱(也称直接信号谱)，通过信号谱转换的噪声谱，或者其他基于该信号谱衍生出来的具有等效对称特性的谱等，本申请实施例对此不作限定。
在频谱信息为谱估计系数时，接收端可以采用传统的谱估计算法得到该谱估计系数，该传输的谱估计算法比如是AR-Burg算法(自回归-Burg算法，Burg表示伯格算法，Burg是一种经典的谱估计算法)等。
S103中接收端获取频谱信息的方式多种多样，以下将以频谱信息为谱估计系数为例对其中的三种方式为例进行讲解。
方式1，接收端可以首先对均衡处理后的业务信号进行判决(硬判决或软判决)，得到判决后的业务信号。之后，接收端可以将均衡处理后的业务信号减去判决后的业务信号，得到信道噪声。最后，接收端可以对该信道噪声进行谱估计，得到谱估计系数，并将该谱估计系数作为频谱信息。
方式2，接收端可以首先对均衡处理后的业务信号依次进行前向纠错码(Forward Error Correction，FEC)的译码和重构，得到重构后的业务信号。其中，对业务信号进行重构是指，对经过FEC的译码后的业务信号进行重新映射。之后，接收端可以将均衡处理后的业务信号减去重构后的业务信号，得到信道噪声。最后，接收端可以对该信道噪声进行谱估计，得到谱估计系数，并将该谱估计系数作为频谱信息。
需要说明的是，方式1中基于判决后的业务信号得到频谱信息，方式2中基于重构后的业务信号得到频谱信息，由于重构后的业务信号的可靠性高于判决后的业务信号的可靠性，因此，方式2中得到的频谱信息的可靠性较高。
方式3，如果接收端包括用于执行窄带滤波补偿(Narrowband Filtering Compensation，NFC)的模块(称为NFC模块)，由于NFC模块在对业务信号进行NFC处理时，通常是基于谱估计系数对业务信号进行滤波，因此，接收端在S103中可以获取NFC模块滤波所基于的谱估计系数，并将该谱估计系数作为频谱信息。这样一来，接收端在执行NFC处理和执行S103的过程中，只需要计算一次谱估计系数，避免了多次计算谱估计系数对计算资源的浪费。
可选地，NFC模块可以采用任一种方法获取谱估计系数，如Burg算法、莱文逊(Levinson-Durbin)算法等。
可选地，如果NFC模块具有多个抽头，那么NFC模块滤波所基于的谱估计系数包括该多个抽头一一对应的多个谱估计系数。此时，接收端可以在该多个谱估计系数中选择除第一个抽头对应的谱估计系数之外的任一谱估计系数作为频谱信息。比如，接收端可以将该多个抽头中第二个或第三个抽头对应的谱估计系数作为频谱信息。
进一步地，S103中以接收端获取一次频谱信息为例，可选地，接收端也可以在S103中多次获取频谱信息，并将多次获取的频谱信息的平均值作为最终获取到的频谱信息，以提升获取到的频谱信息的准确度。其中，多次获取的频谱信息的平均值可以是任一种平均值，如算数平均值、平方平均值、调和平均值或加权平均值等。
可选地，如果接收端包括NFC模块，那么接收端也可以利用NFC模块对均衡处理后的业务信号进行NFC处理，以得到NFC处理后的业务信号。之后，接收端可以基于该NFC处理后的业务信号获取上述频谱信息。接收端基于NFC处理后的业务信号获取频谱信息的过程，可以参考接收端基于均衡处理后的业务信号获取频谱信息的过程，本申请实施例在此不做赘述。
需要说明的是，对业务信号进行NFC处理，能够对业务信号由于信道带宽受限而引入的ISI进行补偿。如果接收端基于NFC处理后的业务信号获取频谱信息，那么获取的频谱信息还能够避免信道带宽受限所带来的影响，提升频谱信息的准确度。
S104、接收端根据业务信号的频谱信息，向发送端发送业务信号的频偏参数。
业务信号的频偏参数用于指示上述偏移量大小和偏移方向中的至少一种信息，比如，频偏参数用于指示该偏移量大小，或者，频偏参数用于指示该偏移方向，或者，频偏参数用于指示该偏移量大小和偏移方向。本申请实施例对此不作限定。
接收端在得到业务信号的频谱信息后，需要根据业务信号的频谱信息，确定业务信号的频偏参数，再将该频偏参数发送给发送端。
需要说明的是，S104中以接收端根据频谱信息向发送端发送频偏参数为例，可选地，接收端在S104中也可以直接将业务信号的频谱信息发送给发送端，再由发送端根据该频谱信息 确定业务信号的频偏参数。总的来说，接收端在S104中可以向发送端发送用于频率调节的信息，该信息可以包括频偏参数或频谱信息，本申请实施例对此不作限定。
S105、发送端根据业务信号的频偏参数，调节发送端的中心频率。
无论S104中接收端发送给发送端的用于频率调节的信息是频偏参数还是频谱信息，发送端均需要获取该频偏参数。当S104中接收端发送的用于频率调节的信息是频偏参数时，发送端直接获取该频偏参数即可，当S104中接收端发送的用于频率调节的信息是频谱信息时，发送端需要根据该频谱信息确定频偏参数，以得到该频偏参数。
频偏参数指示上述偏移量大小和偏移方向中的至少一种信息，发送端可以根据频偏参数所指示的该至少一种信息，确定发送端的中心频率的调节方向和调节量大小，之后根据该调节方向和调节量大小调节发送端的中心频率。
比如，以频偏参数指示上述偏移量大小和偏移方向为例。
若频偏参数的值为+X(指示业务信号的中心频率比光纤上设置的至少一个滤波器的中心频率大X)，那么发送端可以确定发送端的中心频率的调节方向为频率减小的方向，调节量大小为X，发送端可以将发送端的中心频率减小X。
若频偏参数的值为-X(指示业务信号的中心频率比上述至少一个滤波器的中心频率小X)，那么发送端可以确定发送端的中心频率的调节方向为频率增大的方向，调节量大小为X，发送端可以将其中心频率增大X。
由于发送端的中心频率与发送端中数字信号的频率和激光器的工作频率均相关，因此发送端在调节发送端的中心频率时，可以调节发送端中激光器的工作频率(和/或，发送端中数字信号的频率)，从而实现对发送端的中心频率的调节。需要说明的是，发送端的中心频率被调节后，发送端发出的信号(如业务信号和非业务信号)的中心频率被调节，从而能够实现对业务信号的频偏的校正。
S104中，接收端(或发送端)需要根据业务信号的频谱信息，确定业务信号的频偏参数。其中，接收端(或发送端)根据频谱信息确定频偏参数的方式多种多样，以下将以接收端根据频谱信息确定频偏参数的几种可实现方式为例进行讲解。发送端根据频谱信息确定频偏参数的方式可以参考接收端根据频谱信息确定频偏参数的方式，本申请实施例在此不做赘述。
(1)在第一种可实现方式中，频谱信息为业务信号的信道响应。接收端可以首先对信道响应进行快速傅立叶变换，得到频域响应。之后，再根据频域响应和业务信号的波特率(单位可以是赫兹)，得到业务信号的频偏参数。该频偏参数用于指示：业务信号的中心频率相对上述至少一个滤波器的中心频率的偏移量大小和偏移方向。
需要说明的是，信道响应是信道在时域上的响应，频域响应是信道在频域上的响应。利用快速傅里叶变换(fast Fourier transform，FFT)能够将信道响应从时域转换到频域，从而得到频域响应。
FFT具有点数N，N通常是2的n次方(n≥1)，如64、128或256等。接收端在对信道响应进行FFT时，可以先根据FFT的点数N在信道响应中采样，得到N个采样点；之后，再对N个采样点中的每个采样点进行变换，得到业务信号在N个频率下的功率(也即频域响应)。其中，N个采样点与该N个频率一一对应，业务信号在每个所述频率下的功率经过对应的采样点变换得到。
示例地，如表1所示，信道响应包括采样点0.1、0.2和0.3，频域响应包括：业务信号在频率1.1下的功率2.1，业务信号在频率1.2下的功率2.2，以及业务信号在频率1.3下的功率2.3。功率2.1由采样点0.1变换得到；功率2.2由采样点0.2变换得到；功率2.3由采样点0.3变换得到。
表1
采样点 业务信号的频率 业务信号在该频率下的功率
0.1 1.1 2.1
0.2 1.2 2.2
0.3 1.3 2.3
在得到频域响应后，接收端可以将频域响应和业务信号的波特率代入频偏公式，得到频偏参数。其中，频偏公式包括：f＝(N/2-M)*F/N。f表示频偏参数；M表示功率最小的频率对应的采样点的索引；F表示业务信号的波特率。
接收端根据该频偏公式所得到的频偏参数的绝对值能够用于表示上述偏移量大小，频偏参数的正负能够用于表示上述偏移方向。
比如，当频偏参数为正值时，频偏参数用于指示偏移方向为右偏(也即业务信号的中心频率大于上述至少一个滤波器的的中心频率)；当频偏参数为负值时，频偏参数用于指示偏移方向为左偏(也即业务信号的中心频率小于上述至少一个滤波器的中心频率)。
又比如，当频偏参数为正值时，频偏参数用于指示偏移方向为左偏；当频偏参数为负值时，频偏参数用于指示偏移方向为右偏。
(2)在第二种可实现方式中，频谱信息为业务信号的谱估计系数。接收端在确定谱估计系数之后，可以确定该谱估计系数的虚部，并根据该虚部的正负确定频偏参数。此时，频偏参数用于指示业务信号的中心频率相对上述至少一个滤波器的中心频率的偏移方向。
比如，虚部的正负与上述偏移方向相反。当谱估计系数的虚部是正数时，偏移方向为左偏。当谱估计系数的虚部是负数时，偏移方向为右偏。
可选地，接收端在根据该虚部的正负确定频偏参数之前，还可以对该虚部的正负进行核对。比如，当虚部的绝对值小于绝对值阈值时，核对后的虚部为0；当虚部的绝对值大于或等于绝对值阈值时，核对后的虚部与核对之前的虚部相同。之后，接收端可以根据核对后的虚部的正负确定频偏参数。
(3)在第三种可实现方式中，频谱信息为业务信号的谱估计系数。接收端在确定谱估计系数之后，可以确定该谱估计系数的虚部，并根据该虚部确定频偏参数(比如将该虚部作为频偏参数)。此时，频偏参数用于指示业务信号的中心频率相对上述至少一个滤波器的中心频率的偏移方向，并且，该频偏参数还用于指示该虚部的绝对值。
(4)在第四种可实现方式中，接收端可以参考前三种可实现方式中的任一种可实现方式中获取频偏参数的过程，获取上述偏移量大小和偏移方向中至少一种参数。之后，接收端再根据该至少一种参数，得到频偏参数。其中，当该至少一种参数包括偏移量大小时，该频偏参数包括发送端的中心频率的调节量大小；当该至少一种参数包括偏移方向时，该频偏参数包括发送端对其中心频率的调节方向。这样一来，发送端接收到的频偏参数包括调节方向和/或调节量大小，发送端可以按照频偏参数中的调节方向和/或调节量大小，调节发送端的中心 频率，降低了发送端的负载。
S105中以频偏参数用于指示偏移量大小和偏移方向为例。当频偏参数未能指示偏移量大小和偏移方向中的一种参数时，发送端需要采用其他方式确定这种参数。
示例地，在频偏参数用于指示该偏移方向，且不用于指示偏移量大小时，发送端可以根据该偏移方向确定发送端的中心频率的调节方向，并且发送端还可以获取发送端的中心频率的调节量大小。该调节量大小可以预先配置在发送端中，也可以由发送端随机生成，也可以由其他设备发送给发送端，本申请实施例对此不作限定。
又示例地，在频偏参数用于指示该偏移量大小，且不用于指示偏移方向时，发送端可以将该偏移量大小作为发送端的中心频率的调节量大小，并且发送端还可以获取发送端的中心频率的调节方向。该调节方向可以预先配置在发送端中，也可以由发送端随机生成，也可以由其他设备发送给发送端，本申请实施例对此不作限定。并且，在发送端每次调节发送端的中心频率之后，发送端可以再次获取频偏参数(如接收发送端发送的频偏参数)，并判断该频偏参数所指示的偏移量大小是否减小。如果频偏参数所指示的偏移量大小减小，说明发送端对其的中心频率的调节方向是正确的，后续可以继续向该调节方向调节发送端的中心频率。如果频偏参数所指示的偏移量大小增大，说明发送端对其中心频率的调节方向是错误的，后续发送端可以改变其中心频率的调节方向，以向相反的方向调节发送端的中心频率。
进一步地，以上内容中以接收端在S103后直接执行S104(根据频谱信息向发送端发送频偏参数)为例。可选地，接收端也可以是在业务信号的频偏程度大于频偏程度阈值时，才执行S104。在业务信号的频偏程度小于或等于频偏程度阈值时，接收端无需执行S104。
在业务信号的频偏程度大于频偏程度阈值时，接收端可以确定当前业务信号的频偏程度较高，此时接收端可以执行S104，以便于发送端根据频偏参数调节其中心频率，从而对业务信号的频偏进行校正。在业务信号的频偏程度小于或等于频偏程度阈值时，接收端可以确定当前业务信号的频偏程度较低，此时无需对业务信号的频偏进行校正，因此，接收端无需执行S104。
接收端判断业务信号的频偏程度是否大于频偏程度阈值的方式多种多样，以下将以其中的几种可实现方式为例进行讲解。
在第一种可实现方式中，频偏参数用于指示上述偏移量大小，此时，接收端可以判断业务信号的中心频率相对上述至少一个滤波器的中心频率的偏移量大小是否大于偏移量大小阈值。在业务信号的中心频率相对至少一个滤波器的中心频率的偏移量大小大于偏移量大小阈值时，接收端可以确定业务信号的频偏程度大于频偏程度阈值。在业务信号的中心频率相对至少一个滤波器的中心频率的偏移量大小小于或等于偏移量大小阈值时，接收端可以确定业务信号的频偏程度小于或等于频偏程度阈值。
在第二种可实现方式中，频谱信息是业务信号的谱估计系数，此时，接收端可以在谱估计系数的虚部的绝对值大于绝对值阈值时，确定业务信号的频偏程度大于频偏程度阈值；在谱估计系数的虚部的绝对值小于或等于绝对值阈值时，确定业务信号的频偏程度小于或等于频偏程度阈值。
可选地，接收端在向发送端发送频偏参数之前，也可以不对业务信号的频偏程度是否大 于频偏程度阈值进行判断，本申请实施例对此不作限定。
可选地，无论接收端是否对业务信号的频偏程度是否大于频偏程度阈值进行判断，发送端均可以在S105之前对业务信号的频偏程度是否大于频偏程度阈值进行判断，并在确定业务信号的频偏程度大于频偏程度阈值时，才执行S105对发送端的中心频率进行调节。在业务信号的频偏程度小于或等于频偏程度阈值时，发送端无需对其中心频率进行调节。
发送端对业务信号的频偏程度是否大于频偏程度阈值进行判断的方式多种多样，以下将以其中的两种可实现方式为例进行讲解。
在第一种可实现方式中，频偏参数用于指示上述偏移量大小，此时，发送端判断频偏程度是否大于频偏程度阈值的过程，可以参考接收端判断频偏程度是否大于频偏程度阈值的第一种可实现方式，本申请实施例在此不作赘述。
在第二种可实现方式中，发送端可以根据谱估计系数的虚部对业务信号的频偏程度是否大于频偏程度阈值进行判断。此时，在S104中接收端发送的频偏参数(或频谱信息)包括谱估计系数的虚部。发送端判断频偏程度是否大于频偏程度阈值的过程，可以参考接收端判断频偏程度是否大于频偏程度阈值的第二种可实现方式，本申请实施例在此不作赘述。
需要说明的是，在发送端和接收端均对业务信号的频偏程度是否大于频偏程度阈值进行判断时，通过发送端和接收端的双重判断，提升了判断结果的准确度。
可选地，发送端和接收端可以重复执行本申请实施例提供的通信方法，以不断对业务信号的频偏程度是否大于频偏程度阈值进行判断。在业务信号的频偏程度大于频偏程度阈值时，执行S104和S105，从而将业务信号的频偏程度调节至小于或等于频偏程度阈值的状态。
进一步地，如果接收端在业务信号的频偏程度大于频偏程度阈值时才执行S104。那么在业务信号的频偏程度小于或等于频偏程度阈值时，接收端无需执行S104，此时，接收端可以向发送端发送用于预补偿的信息，该信息包括业务信号的频谱信息。发送端可以根据该用于预补偿的信息对业务信号进行预补偿。
业务信号在传输过程中受到的影响包括：由于业务信号频偏所带来的滤波器对业务信号滤波的第一影响，以及除第一影响之外的第二影响(如发送端和接收端上光电器件对业务信号滤波带来的影响，以及在业务信号未频偏时滤波器对业务信号滤波所带来的影响)。在业务信号的频偏程度小于频偏程度阈值时，第一影响可以忽略不计，此时频谱信息主要反映上述第二影响。因此，在业务信号的频偏程度小于频偏程度阈值时，接收端可以将业务信号的频谱信息反馈给发送端，以便于发送端根据该频谱信息对业务信号进行预补偿，以消除上述第二影响，进一步降低滤波代价。
示例地，发送端包括数字信号处理(digital signal processing，DSP)模块，发送端可以利用该DSP模块根据业务信号的频谱信息对业务信号进行预补偿。
另外，在接收端具有NFC模块时，该NFC模块会获取业务信号的谱估计系数，并根据第一频率更新谱估计系数中的实部，以及根据第二频率更新谱估计系数中的虚部，以更新谱估计系数。NFC模块还会根据当前的谱估计系数，对业务信号进行滤波。
一方面，在本申请实施例中，接收端可以根据第一条件对第一频率进行调整。比如，在第一条件满足时，接收端可以降低第一频率(降低后的第一频率可以大于或等于零)。其中，第一条件包括：接收端向发送端发送频谱信息。换句话说，在接收端向发送端发送用于预补 偿的频谱信息之后，接收端可以将第一频率降低。
需要说明的是，接收端中的NFC模块在根据谱估计系数对业务信号进行滤波时，谱估计系数中的实部与消除业务信号受到的第二影响相关。谱估计系数中实部的更新频率(上述第一频率)越大，NFC模块对第二影响的消除能力越高。本申请实施例中，在接收端向发送端发送用于预补偿的频谱信息后，发送端可以根据该频谱信息对业务信号进行预补偿，以降低或消除第二影响。此时，谱估计系数中实部会变小，降低谱估计系数中实部的更新频率(上述第一频率)，虽然会降低NFC模块对第二影响的消除能力，但由于业务信号在发送端已经进行了预补偿，所以，第二影响不会较高。并且，由于降低了谱估计系数中实部的更新频率，因此，降低了NFC模块的功耗，降低了接收端的功耗。
可选地，上述第一条件还包括：谱估计系数的实部的绝对值小于第一阈值。由于谱估计系数的实部的绝对值的大小与NFC模块对第二影响的消除能力正相关，在谱估计系数的实部的绝对值小于第一阈值时，说明第二影响较小。此时降低谱估计系数中实部的更新频率，虽然会降低NFC模块对第二影响的消除能力，但能够保证经过NFC模块滤波之后的业务信号受到的第二影响较小。
可选地，接收端可以周期性地根据第一条件对该第一频率进行调整，其中，接收端调整第一频率的周期可以是任意周期，如分钟级的周期、小时级的周期或天级的周期等。
另一方面，在本申请实施例中，接收端还可以根据第二条件对第二频率进行调整。比如，在第二条件满足时，接收端可以降低第二频率(降低后的第二频率可以大于或等于零)，其中，第二条件包括：接收端向发送端发送用于频率调节的信息(如上述频偏参数)。
需要说明的是，接收端中的NFC模块在根据谱估计系数对业务信号进行滤波时，谱估计系数中的虚部与消除业务信号受到的第一影响相关。谱估计系数中虚部的更新频率(上述第二频率)越大，NFC模块对第一影响的消除能力越高。
在接收端向发送端发送频偏参数之后，发送端可以根据该频偏参数调节发送端的中心频率，从而对业务信号的频偏进行一定的校正。此时，谱估计系数中虚部会变小，降低谱估计系数中虚部的更新频率(上述第二频率)，虽然会降低NFC模块对第一影响的消除能力，但由于业务信号的频偏程度已经降低，所以，业务信号的频偏程度不会较高。并且，由于降低了谱估计系数中虚部的更新频率，因此，降低了NFC模块的功耗，降低了接收端的功耗。
可选地，上述第二条件还包括：谱估计系数的虚部的绝对值小于第二阈值。由于谱估计系数的虚部的绝对值的大小与业务信号的频偏程度相关，在谱估计系数的虚部的绝对值小于第二阈值时，说明业务信号的频偏程度较小，此时降低谱估计系数中虚部的更新频率，虽然会降低NFC模块对第一影响的消除能力，但能够保证经过NFC模块滤波之后的业务信号受到的第一影响较小。
可选地，接收端可以周期性地根据第二条件对该第二频率进行调整，其中，接收端调整第二频率的周期可以是任意周期，如分钟级的周期、小时级的周期或天级的周期等。
以下将结合图7对本申请实施例提供的通信方法进行举例说明。
如图7所示，接收端包括：接收模块、均衡模块、频谱信息获取模块、频偏参数获取模块以及发送模块。其中，接收模块用于接收发送端发送的业务信号。均衡模块用于对业务信号进行均衡处理，得到均衡处理后的业务信号。频谱信息获取模块用于根据均衡处理后的业 务信号，获取业务信号的频谱信息。频偏参数获取模块用于根据该频谱信息，得到与频谱信息不同的频偏参数。发送模块用于将该频偏参数发送至发送端。
频谱信息获取模块获取频谱信息的方式多种多样。
在频谱信息获取模块获取频谱信息的第一种实现方式中，接收端还包括判决模块，判决模块用于对均衡处理后的业务信号进行判决。频谱信息获取模块可以用于将均衡处理后的业务信号减去判决后的业务信号，得到信道噪声，再根据信道噪声得到谱估计系数(频谱信息的一个例子)。
在频谱信息获取模块获取频谱信息的第二种实现方式中，接收端还包括FEC译码模块和重构模块。FEC译码模块用于对均衡处理后的业务信号进行FEC的译码，重构模块用于对译码后的业务信号进行重构。频谱信息获取模块可以用于将均衡处理后的业务信号减去重构后的业务信号，得到信道噪声，再根据信道噪声得到谱估计系数。
可选地，接收端还包括NFC模块，接收端可以对均衡处理后的业务信号进行NFC处理，得到NFC处理后的业务信号。接收端可以基于该NFC处理后的业务信号获取上述频谱信息。接收端基于NFC处理后的业务信号获取频谱信息的过程，可以参考接收端基于均衡处理后的业务信号获取频谱信息的过程，本申请实施例在此不做赘述。
比如，在频谱信息获取模块获取频谱信息的第一种实现方式中，判决模块可以对该NFC处理后的业务信号进行判决，频谱信息获取模块可以将NFC处理后的业务信号减去判决后的业务信号，得到信道噪声，再根据信道噪声得到谱估计系数。
在频谱信息获取模块获取频谱信息的第二种实现方式中，FEC译码模块可以用于对NFC处理后的业务信号依次进行FEC的译码，频谱信息获取模块可以用于将NFC处理后的业务信号减去重构后的业务信号，得到信道噪声，再根据信道噪声得到谱估计系数。
可选地，在接收端包括NFC模块时，接收端也可以不基于NFC处理后的业务信号获取上述频谱信息。比如，接收端还可以包括选择模块，该选择模块用于选择获取上述频谱信息所基于的业务信号是均衡处理后的业务信号，还是NFC处理后的业务信号。在频谱信息获取模块获取频谱信息的第一种实现方式中，选择模块还用于将选择得到的信号分别输入判决模块和频谱信息获取模块。在频谱信息获取模块获取频谱信息的第二种实现方式中，选择模块还用于将选择得到的信号输入频谱信息获取模块。
可选地，接收端还可以包括除图7所示的模块之外的其他模块。
如图8所示，接收端包括：相干接收机(Integrated Coherent Receiver，ICR)模块、模拟数字转换器(analog to digital converter，ADC)模块、时钟恢复(time recovery，TR)模块、均衡模块、NFC模块和FEC译码模块。TR模块、均衡模块和NFC模块可以在接收端的DSP模块(图8中未示出)中实现。其中，ICR模块用于实现图2中光探测器的功能，TR模块、均衡模块、NFC模块和FEC译码模块用于实现图2中信号解调模块的功能。
相应地，发送端包括：FEC编码模块、DSP模块、数字模拟转换器(digital to analog converter，DAC)模块、驱动模块、调制模块和激光器。其中，FEC编码模块和DSP模块用于实现图2中数字信号调制模块的功能，调制模块用于实现图2中调制器的功能。
在发送端中，FEC编码模块用于对待传输的数据进行FEC的编码，得到数字信号；DSP模块用于对该数字信号进行预补偿，DAC模块用于将预补偿后的数字信号转换为模拟信号；驱动模块用于将DAC输出后的电信号(上述模拟信号)放大；激光器用于发出激光；调制模 块用于根据模拟信号对激光器发出的激光进行调制，得到业务信号。
业务信号会经过光纤以及光纤上的至少一个WSS传输至接收端。
在接收端中，ICR模块用于将接收到的业务信号转换为模拟信号；ADC模块用于将该模拟信号转换为数字信号；TR模块用于对该数字信号进行时钟恢复；均衡模块用于对时钟恢复后的数字信号进行均衡处理，得到均衡处理后的业务信号；NFC模块用于对均衡处理后的业务信号进行NFC处理，得到NFC处理后的业务信号；FEC译码模块用于对NFC处理后的业务信号进行FEC的译码，得到发送端需要传输的数据。
请继续参考图8，接收端还包括频偏模块。
在一种实现方式中，频偏模块具有图7中的频谱信息获取模块和判决模块的功能。
一方面，如果接收端基于均衡处理后的业务信号，获取上述频谱信息，那么如图8所示，频偏模块与均衡模块连接，用于根据均衡模块输出的均衡处理后的业务信号，获取上述频谱信息。
另一方面，如果接收端基于NFC处理后的业务信号获取上述频谱信息，那么频偏模块与NFC模块连接，用于根据NFC模块输出的NFC处理后的业务信号，获取上述频谱信息。
在另一种实现方式中，频偏模块具有图7中的频谱信息获取模块和重构模块的功能。
一方面，如果接收端基于均衡处理后的业务信号，获取上述频谱信息，那么频偏模块与均衡模块和FEC译码模块连接，用于根据均衡模块输出的均衡处理后的业务信号，以及FEC译码模块译码后的业务信号，获取上述频谱信息。
另一方面，如果接收端基于NFC处理后的业务信号，获取上述频谱信息，那么频偏模块与FEC译码模块和NFC模块连接，用于根据NFC模块输出的NFC处理后的业务信号，以及FEC译码模块译码后的业务信号，获取上述频谱信息。
进一步地，无论频偏模块与接收端中的其他模块如何连接，频偏模块均可以与发送端连接(如与发送端中的DSP模块连接)，用于根据频谱信息向发送端发送频偏参数。
需要说明的是，图7和图8所示的接收端中的各个模块可以通过软件和/或硬件实现，并且，不同的模块可以相互独立或者集成为一个模块，本申请实施例对此不作限定。
根据本申请实施例提供的以上通信方法可知，接收端可以根据发送端发送的业务信号，向发送端发送频偏参数，以指示发送端调节其中心频率，进而实现对业务信号的频偏的校正。目前，存在一些对业务信号的频偏进行校正的方案，但这些方案均存在一些问题，以下将对这些方案存在的问题进行详细说明。
方案(1)：发送端在向接收端发送业务信号之前，向接收端发送导频序列(或训练序列)。接收端可以根据接收到的导频序列(或训练序列)指示发送端调节激光器的工作频率，以对发送端的中心频率与上述至少一个滤波器的中心频率的偏移进行校正。
但是，发送端向接收端发送导频序列(或训练序列)会占用一定的频谱资源，使得频谱资源的利用率较低。本申请实施例提供的通信方法中，发送端无需向接收端发送导频序列或训练序列，因此，避免了发送这些序列对频谱资源的占用，避免了频谱资源的利用率较低的情况。
方案(2)：接收端读取发送端发送的信号的平均误码率(Bit Error Rate，BER)，然后根据该平均BER指示发送端调节其的中心频率。之后，接收端再次读取该平均BER，并确定 该平均BER的变化趋势。如果该平均BER的变化趋势为下降趋势，那么说明之前发送端调节其中心频率的方向是正确的，此时接收端可以继续指示发送端朝这个方向调节该中心频率。如果该平均BER的变化趋势为上升趋势，那么说明之前发送端调节其中心频率的方向是错误的，此时接收端可以指示发送端朝相反的方向调节上述中心频率。如此往复，直至平均BER达到局部最优值。
但是，发送端第一次对其中心频率的调节属于盲调，盲调较容易不收敛，容易找不到上述局部最优值，从而无法将业务信号的频偏调整到比较小的状态。并且，接收端确定出的平均BER会受到环境因素(如光纤摆动、打雷、闪电等)的影响，导致平均BER的准确度较低，因此，接收端根据平均BER指示发送端调节其中心频率的效果较差。
本申请实施例提供的方法中，接收端向发送端反馈的频偏参数能够指示偏移量大小和偏移方向中的至少一种信息，此时发送端根据这些信息调整中心频率并不是盲调，所以不存在不收敛的问题，能够将业务信号的频偏调整到比较小的状态。并且，接收端发送的频偏参数所基于的频谱信息是根据均衡处理后的业务信号确定的，在对业务信号进行均衡处理的过程中，消除了业务信号所受到的环境因素的影响。因此，频偏参数所指示的信息较为准确，发送端根据频偏参数对业务信号的频偏的校正效果较好，实现了在复杂场景下对偏移量大小和偏移方向中至少一种信息的精准估计。
方案(3)：接收端提取发送端发送的信号的功率谱，并根据功率谱的对称性确定发送端的中心频率的调节方向，进而指示发送端向该调节方向调节其中心频率。
但是，接收端只能向发送端指示调节方向，无法指示调节量大小，发送端调节其中心频率的效果较差。而且，接收端对功率谱进行存储和分析需要占用较多资源，影响接收端的正常运行。另外，接收端提取出的功率谱会受到环境因素(如光纤摆动、打雷、闪电等)的影响，导致功率谱的准确度较低，因此，接收端根据功率谱确定出的调节方向的准确度较低，进而接收端指示发送端调节其中心频率的效果较差。
本申请实施例提供的方法中，接收端向发送端发送的频偏参数能够指示偏移方向和偏移量大小，因此，发送端调节其中心频率的效果较好。并且，在频谱信息为谱估计系数时，如果接收端包括NFC模块，那么就可以利用已有的NFC模块获取谱估计系数，而无需另外占用其他资源获取频谱信息，降低了对接收端正常运行的影响。并且，接收端发送的频偏参数所基于的频谱信息是根据均衡处理后的业务信号确定的，因此发送端根据频偏参数对业务信号的频偏的校正效果较好，实现了在复杂场景下对偏移量大小和偏移方向中至少一种信息的精准估计。
以下将以两个示例为例(均以滤波器为WSS为例)，对本申请实施例提供的通信方法对频偏的校正效果进行说明。
示例(1)，假设接收端采用确定频偏参数的第一种可实现方式，此时，频谱信息为业务信号的信道响应，接收端可以首先对信道响应进行快速傅立叶变换得到频域响应，再根据频域响应和业务信号的波特率得到业务信号的频偏参数。
在发送端和接收端之间的光纤上串联有27个WSS时，业务信号在三种频偏情况下的频域响应如图9所示。这三种频偏情况包括：业务信号的中心频率相对27个WSS的中心频率的频偏为2.5吉赫兹(GHz)的频偏情况1，业务信号的中心频率相对该27个WSS的中心频 率的频偏为-2.5GHz的频偏情况2，以及业务信号的中心频率相对27个WSS的中心频率的频偏为0GHz的频偏情况3。
需要说明的是，图9中的横坐标表示频率，单位为GHz，纵坐标表示业务信号在某一频率下的功率，单位为分别(dB)。并且，横坐标中值为0GHz的频率为当前信号波特率下的截止频率。图9所示的每种频偏情况下的频域响应中，功率最小的频率与该截止频率之差为接收端确定出的频偏参数。
如图9所示，业务信号在频偏情况1下的频域响应中，功率最小的频率与该截止频率之差为2.10GHz，频偏参数为2.10GHz(与2.5GHz较为相似)。业务信号在频偏情况2下的频域响应中，功率最小的频率与该截止频率之差为-2.27GHz，频偏参数为-2.27GHz(与-2.5GHz较为相似)。业务信号在频偏情况3下的频域响应中，功率最小的频率与该截止频率之差为0.07GHz(图9中未标出)，频偏参数为0.07GHz(与0GHz较为相似)。
进一步地，如果将图9中的三种频偏情况修改为：业务信号的中心频率相对27个WSS的中心频率的频偏为2GHz的频偏情况1，业务信号的中心频率相对27个WSS的中心频率的频偏为-2GHz的频偏情况2，以及业务信号的中心频率相对27个WSS的中心频率的频偏为0GHz的频偏情况3。那么，业务信号在这三种频偏情况下的频域响应如图10所示。
请参考图10，业务信号在频偏情况1下的频域响应中，功率最小的频率与该截止频率之差为1.84GHz，频偏参数为2.10GHz(与2GHz较为相似)。业务信号在频偏情况2下的频域响应中，功率最小的频率与该截止频率之差为-1.64GHz，频偏参数为-1.64GHz(与-2GHz较为相似)。业务信号在频偏情况3下的频域响应中，功率最小的频率与该截止频率之差为0.07GHz，频偏参数为0.07GHz(与0GHz较为相似)。
可见，本申请实施例中确定出的频偏参数所指示的偏移方向与实际的偏移方向较为相似，频偏参数指示的偏移量大小与实际的偏移量大小也较为相似。这样一来，发送端根据该频偏参数调节其中心频率之后，业务信号的频偏便能够得到有效地校正。
示例(2)，假设接收端采用确定频偏参数的第二种可实现方式，此时，频谱信息为业务信号的谱估计系数。接收端可以根据谱估计系数的虚部的正负确定频偏参数。此时，频偏参数用于指示业务信号的频偏方向(业务信号的中心频率相对上述27个WSS的中心频率的偏移方向。
如果该谱估计系数为NFC模块执行滤波所基于的谱估计系数，且NFC模块具有4个抽头，那么NFC模块会基于这四个抽头一一对应的四个谱估计系数进行滤波。示例地，假设业务信号的调制格式为正交振幅调制(Quadrature Amplitude Modulation，QAM)格式，且发送端和接收端之间信道的容量为400吉赫兹/每秒。在发送端和接收端之间的光纤上串联有27个WSS时，在七种频偏情况下NFC模块所基于的四个谱估计系数的实部和虚部分别如表2所示。
表2
Figure PCTCN2022105087-appb-000001
Figure PCTCN2022105087-appb-000002
在示例(2)中，接收端可以采用第二个抽头对应的谱估计系数作为频偏参数。根据表2可知，业务信号的中心频率相对27个WSS的中心频率的频偏越大，第二个抽头对应的谱估计系数的虚部越大，且业务信号的频偏方向与第二个抽头对应的谱估计系数的虚部的正负相反。
并且，对表2中的偏移情况1、4和7下后三个抽头对应的谱估计系数的虚部进行监控，可以得到如图11所示的在偏移情况1、4和7下第二个抽头对应的谱估计系数中虚部的变化情况，如图12所示的在偏移情况1、4和7下第三个抽头对应的谱估计系数中虚部的变化情况，以及如图13所示的在偏移情况1、4和7下第四个抽头对应的谱估计系数中虚部的变化情况。图11、12和13中的横轴表示监控的时间，纵轴表示该虚部的值。从这三幅图可以看出，业务信号的频偏方向与这些虚部的正负相反。
所以，在示例(2)中，当该第二个抽头对应的谱估计系数的虚部是正数时，接收端根据该虚部的正负所确定出的频偏参数可以用于指示的偏移方向为左偏(业务信号的中心频率小于27个WSS的中心频率)。当该第二个抽头对应的谱估计系数的虚部是负数时，接收端根据该虚部的正负所确定出的频偏参数可以用于指示的偏移方向为右偏(业务信号的中心频率大于27个WSS的中心频率)。
可见，本申请实施例中确定出的频偏参数所指示的偏移方向与实际的偏移方向一致。这样一来，发送端根据该频偏参数调节其中心频率之后，业务信号的频偏便能够得到有效地校正。另外，经过实验得知，光纤上串连的WSS越多，谱估计系数的实部的绝对值越大。
上文中结合图1至图13，详细描述了本申请所提供的通信方法，可以理解的是，通信装置为了实现上述各方法所描述的功能，其需包含执行各个功能相应的硬件和/或软件模块。结 合本文中所公开的实施例描述的各方法的执行过程，本申请能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。本领域技术人员可以结合实施例对每个特定的应用来使用不同方式来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
本实施例可以根据上述方法实施例对相应的通信装置进行功能模块的划分，例如，可以对应各个功能划分各个功能模块，也可以将两个或两个以上的功能集成在一个处理模块中。上述集成的模块可以采用硬件的形式实现。
当采用功能模块划分方式时，下面将结合图14和图15描述本申请所提供的通信装置。
图14为本申请实施例提供的一种通信装置的框图，该通信装置例如可以是前述各实施例中的接收端。该接收端与发送端通过光纤连接，光纤上设置有至少一个滤波器。如图14所示，该通信装置包括：接收模块1401、获取模块1402和第一发送模块1403。
在第一种可实现方式中，接收模块1401用于接收所述发送端发送的业务信号。接收模块1401用于执行的操作可以参考上述S101中与接收端相关的内容。获取模块1402用于获取所述业务信号的频谱信息；获取模块1402用于执行的操作可以参考上述S102和S103中与接收端相关的内容。第一发送模块1403用于根据所述频谱信息，向所述发送端发送所述业务信号的频偏参数；所述频偏参数用于指示：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。第一发送模块1403用于执行的操作可以参考上述S104中与接收端相关的内容。
在第二种可实现方式中，接收模块1401用于接收所述发送端发送的业务信号，接收模块1401用于执行的操作可以参考上述S101中与接收端相关的内容。获取模块1402用于获取所述业务信号的频谱信息，获取模块1402用于执行的操作可以参考上述S102和S103中与接收端相关的内容。第一发送模块1403用于向所述发送端发送所述频谱信息。在这种情况下，发送端可以在接收接收端发送的业务信号的频谱信息后，根据该频谱信息确定上述频偏参数，进而根据该频偏参数调节发送端的中心频率。
综上所述，在本申请实施例提供的通信装置中，第一发送模块能够向发送端发送频偏参数，且频偏参数用于指示业务信号的中心频率相对光纤上串联的至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。或者，第一发送模块能够向发送端发送频谱信息，以便于发送端根据该频谱信息确定频偏参数，且频偏参数用于指示业务信号的中心频率相对光纤上串联的至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。之后，发送端可以根据该频偏参数指示的该至少一种信息调节发送端的中心频率。这样一来，便实现了对业务信号的频偏进行校正，进而降低了业务信号的ISI，降低了滤波器对业务信号的滤波代价。保证了发送端和接收端之间的通信效果，使得发送端和接收端之间的业务信号能够长距离传输。
接收模块1401、获取模块1402和第一发送模块1403可以通过软件和/硬件的方式实现，比如，接收模块1401、获取模块1402和第一发送模块1403均可以在接收端的处理器中实现。
在上述第一种可实现方式和第二种可实现方式中，上述业务信号的频谱信息可以是指业务信号的信号谱和/或噪声谱的信息，其中，噪声谱能指示噪声对业务信号的影响。业务信号在从发送端传输至接收端的过程中，会受到噪声的影响，频谱信息能够指示噪声对业务信号的影响。
示例地，在上述第一种可实现方式和第二种可实现方式中，业务信号的频谱信息包括业务信号的信道响应或谱估计系数。信道响应和谱估计系数均能够反映业务信号的信号谱和/或噪声谱的信息。
一方面，在频谱信息包括信道响应的情况下，上述第一种可实现方式和第二种可实现方式中的所述通信装置还包括：第一处理模块(图14中未示出)和第二处理模块(图14中未示出)，第一处理模块，用于对所述信道响应进行快速傅立叶变换，得到频域响应；第二处理模块，用于根据所述频域响应和所述业务信号的波特率，得到所述频偏参数。第一处理模块和第二处理模块可以通过软件和/硬件的方式实现，比如，第一处理模块和第二处理模块均可以在接收端的处理器中实现。
示例地，所述信道响应包括N个采样点，N表示所述快速傅里叶变换的点数；所述频域响应包括所述业务信号在N个频率下的功率，且所述N个采样点与所述N个频率一一对应，所述业务信号在每个所述频率下的功率经过对应的采样点变换得到；所述第二处理模块用于：根据频偏公式，得到所述频偏参数；其中，所述频偏公式包括：f＝(N/2-M)*F/N；f表示所述频偏参数；M表示功率最小的所述频率对应的采样点的索引；F表示所述业务信号的波特率。
另一方面，在频谱信息包括谱估计系数的情况下，上述第一种可实现方式和第二种可实现方式中的所述通信装置还包括：第一确定模块(图14中未示出)和第二确定模块(图14中未示出)。第一确定模块，用于根据所述频谱信息确定所述谱估计系数的虚部；第二确定模块，用于根据所述谱估计系数的虚部的正负确定所述频偏参数，所述至少一种信息包括所述偏移方向。第一确定模块和第二确定模块可以通过软件和/硬件的方式实现，比如，第一确定模块和第二确定模块均可以在接收端的处理器中实现。
又一方面，在频谱信息包括谱估计系数的情况下，上述第一种可实现方式和第二种可实现方式中的所述通信装置还包括：第三确定模块(图14中未示出)和第四确定模块(图14中未示出)。第三确定模块，用于根据所述频谱信息确定所述谱估计系数的虚部；第四确定模块，用于根据所述谱估计系数的虚部确定所述频偏参数，所述至少一种信息包括所述偏移方向，所述频偏参数还用于指示所述谱估计系数的虚部的绝对值。第三确定模块和第四确定模块可以通过软件和/硬件的方式实现，比如，第三确定模块和第四确定模块均可以在接收端的处理器中实现。
可选地，在上述第一种可实现方式中，接收端在向所述发送端发送所述业务信号的频偏参数之前，还可以利用第五确定模块(图14中未示出)确定所述业务信号的频偏程度大于频偏程度阈值。在上述第二种可实现方式中，接收端在向所述发送端发送所述业务信号的频谱信息之前，也可以利用第五确定模块(图14中未示出)确定所述业务信号的频偏程度大于频偏程度阈值。其中，所述业务信号的频偏程度为：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的频偏程度。在业务信号的频偏程度大于频偏程度阈值时，接收端可以确定当前业务信号的频偏程度较高，此时接收端可以向所述发送端发送第一种可实现方式中的频偏参数或第二种可实现方式中的频谱信息，以便于发送端根据接收到的信息调节其中心频率，从而对业务信号的频偏进行校正。在业务信号的频偏程度小于或等于频偏程度阈值时，接收端可以确定当前业务信号的频偏程度较低，此时无需对业务信号的频偏进行校正，因此，接收端无需向所述发送端发送第一种可实现方式中的频偏参数或第二种可实现方式中的频谱 信息。第五确定模块可以通过软件和/硬件的方式实现，比如，第五确定模块均可以在接收端的处理器中实现。
在上述第一种可实现方式和第二种可实现方式中，接收端判断业务信号的频偏程度是否大于频偏程度阈值的方式多种多样，以下将以其中的两种可实现方式为例进行讲解。
在第一种可实现方式中，第五确定模块会根据频谱信息确定频偏参数，且频偏参数指示的至少一种信息包括所述偏移量大小。此时，接收端可以在所述偏移量大小大于偏移量大小阈值时，确定所述业务信号的频偏程度大于频偏程度阈值。
在第二种可实现方式中，频谱信息是业务信号的谱估计系数，此时，接收端可以在谱估计系数的虚部的绝对值大于绝对值阈值时，可以利用第六确定模块(图14中未示出)确定业务信号的频偏程度大于频偏程度阈值；在谱估计系数的虚部的绝对值小于或等于绝对值阈值时，确定业务信号的频偏程度小于或等于频偏程度阈值。第六确定模块可以通过软件和/硬件的方式实现，比如，第六确定模块可以在接收端的处理器中实现。
可选地，在上述第一种可实现方式和第二种可实现方式中，获取模块1402在获取所述业务信号的频谱信息时，可以首先对所述业务信号进行均衡处理；之后，再根据所述均衡处理后的所述业务信号，获取所述频谱信息。接收端对业务信号进行均衡处理能够消除业务信号受到的环境因素(如光纤摆动、打雷或闪电等)影响，提升获取到的频谱信息的准确度。可选地，获取模块1402中用于对对所述业务信号进行均衡处理的部分可以在接收端的DSP中实现。
可选地，在上述第一种可实现方式中，所述通信装置还包括：第二发送模块(图14中未示出)，用于在所述业务信号的频偏程度小于或等于频偏程度阈值时，向所述发送端发送所述频谱信息。发送端可以根据该频谱信息对业务信号进行预补偿。需要说明的是，业务信号在传输过程中受到的影响包括：由于业务信号频偏所带来的滤波器对业务信号滤波的第一影响，以及除第一影响之外的第二影响(如发送端和接收端上光电器件对业务信号滤波带来的影响，以及在业务信号未频偏时滤波器对业务信号滤波所带来的影响)。在业务信号的频偏程度小于频偏程度阈值时，第一影响可以忽略不计，此时频谱信息主要反映上述第二影响。因此，在业务信号的频偏程度小于频偏程度阈值时，接收端可以将业务信号的频谱信息反馈给发送端，以便于发送端根据该频谱信息对业务信号进行预补偿，以消除上述第二影响，进一步降低滤波代价。第二发送模块可以通过软件和/硬件的方式实现，比如，第二发送模块可以在接收端的处理器中实现。
可选地，在上述第一种可实现方式中，所述通信装置包括：第一更新模块(图14中未示出)、第一滤波模块(图14中未示出)和第一降低模块(图14中未示出)。其中，第一更新模块，用于在获取所述业务信号的谱估计系数后，根据第一频率更新所述谱估计系数中的实部，以更新所述谱估计系数；第一滤波模块，用于根据当前的所述谱估计系数，对所述业务信号进行滤波；第一降低模块，用于在第一条件满足时，降低所述第一频率，所述第一条件包括：所述接收端向所述发送端发送所述频谱信息。换句话说，在接收端向发送端发送用于预补偿的频谱信息之后，接收端可以将第一频率降低。需要说明的是，接收端在根据谱估计系数对业务信号进行滤波时，谱估计系数中的实部与消除业务信号受到的第二影响相关。谱估计系数中实部的更新频率(上述第一频率)越大，接收端在根据谱估计系数对业务信号进行滤波对第二影响的消除能力越高。本申请实施例中，在接收端向发送端发送用于预补偿 的频谱信息后，发送端可以根据该频谱信息对业务信号进行预补偿，以降低或消除第二影响。此时，谱估计系数中实部会变小，降低谱估计系数中实部的更新频率(上述第一频率)，虽然会降低接收端对第二影响的消除能力，但由于业务信号在发送端已经进行了预补偿，所以，第二影响不会较高。并且，由于降低了谱估计系数中实部的更新频率，因此，降低了接收端的功耗。第一更新模块、第一滤波模块和第一降低模块可以通过软件和/硬件的方式实现，比如，第一更新模块、第一滤波模块和第一降低模块均可以在接收端的DSP中实现。
可选地，所述第一条件还包括：所述实部的绝对值小于第一阈值。由于谱估计系数的实部的绝对值的大小与接收端对第二影响的消除能力正相关，在谱估计系数的实部的绝对值小于第一阈值时，说明第二影响较小。此时降低谱估计系数中实部的更新频率，虽然会降低接收端对第二影响的消除能力，但能够保证经过接收端滤波之后的业务信号受到的第二影响较小。
可选地，在上述第一种可实现方式和第二种可实现方式中，所述通信装置包括：第二更新模块(图14中未示出)、第二滤波模块(图14中未示出)和第二降低模块(图14中未示出)。第二更新模块，用于在获取所述业务信号的谱估计系数后，根据第二频率更新所述谱估计系数中的虚部，以更新所述谱估计系数；第二滤波模块，用于根据当前的所述谱估计系数，对所述业务信号进行滤波；第二降低模块，用于在第二条件满足时，降低所述第二频率。在上述第一种可实现方式中，所述第二条件包括：所述接收端向所述发送端发送所述频偏参数。在上述第二种可实现方式中，所述第二条件包括：所述接收端向所述发送端发送所述频谱信息。第二更新模块、第二滤波模块和第二降低模块可以通过软件和/硬件的方式实现，比如，第二更新模块、第二滤波模块和第二降低模块均可以在接收端的DSP中实现。
需要说明的是，接收端中的接收端在根据谱估计系数对业务信号进行滤波时，谱估计系数中的虚部与消除业务信号受到的第一影响相关。谱估计系数中虚部的更新频率(上述第二频率)越大，接收端对第一影响的消除能力越高。
在接收端向发送端发送第一种可实现方式中的频偏参数或第二种可实现方式中的频谱信息之后，发送端可以根据接收到的信息调节发送端的中心频率，从而对业务信号的频偏进行一定的校正。此时，谱估计系数中虚部会变小，降低谱估计系数中虚部的更新频率(上述第二频率)，虽然会降低接收端对第一影响的消除能力，但由于业务信号的频偏程度已经降低，所以，业务信号的频偏程度不会较高。并且，由于降低了谱估计系数中虚部的更新频率，因此，降低了接收端的功耗，降低了接收端的功耗。
可选地，上述第二条件还包括：谱估计系数的虚部的绝对值小于第二阈值。由于谱估计系数的虚部的绝对值的大小与业务信号的频偏程度相关，在谱估计系数的虚部的绝对值小于第二阈值时，说明业务信号的频偏程度较小，此时降低谱估计系数中虚部的更新频率，虽然会降低接收端对第一影响的消除能力，但能够保证经过接收端滤波之后的业务信号受到的第一影响较小。
图15为本申请实施例提供的一种通信装置的框图，该通信装置例如可以是前述各实施例中的发送端。发送端和接收端通过光纤连接，光纤上设置有至少一个滤波器。如图15所示，该通信装置包括：获取模块1501和调节模块1502。
获取模块1501，用于获取业务信号的频偏参数，所述频偏参数用于指示：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信 息；所述频偏参数是根据所述业务信号的频谱信息确定的参数；
调节模块1502，用于根据所述频偏参数所指示的所述至少一种信息，调节所述发送端的中心频率。调节模块1502用于执行的操作可以参考上述S105中与发送端相关的内容。
在本申请实施例提供的通信装置中，获取模块能够获取到频偏参数，且频偏参数用于指示业务信号的中心频率相对光纤上串联的至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。并且，调节模块可以根据该频偏参数指示的该至少一种信息调节发送端的中心频率。这样一来，便实现了对业务信号的频偏进行校正，进而降低了业务信号的ISI，降低了滤波器对业务信号的滤波代价。保证了发送端和接收端之间的通信效果，使得发送端和接收端之间的业务信号能够长距离传输。
可选地，由于发送端的中心频率与发送端中数字信号的频率和激光器的工作频率均相关，因此调节模块1502在调节发送端的中心频率时，可以调节发送端中激光器的工作频率(和/或，发送端中数字信号的频率)，从而实现对发送端的中心频率的调节。在发送端的中心频率被调节后，发送端发出的信号(如业务信号和非业务信号)的中心频率被调节，从而能够实现对业务信号的频偏的校正。
获取模块和调节模块可以通过软件和/硬件的方式实现。比如，在调节模块调节发送端中数字信号的频率以调节发送端的中心频率时，获取模块和调节模块均可以在发送端的DSP模块中实现。又比如，在调节模块调节发送端中激光器的工作频率以调节发送端的中心频率时，获取模块和调节模块均可以在发送端的激光器中实现。可选地，获取模块和调节模块中的部分功能也可以在发送端的处理器上实现。
获取模块1501获取频偏参数的方式多种多样。
在获取模块1501获取频偏参数的第一种可选方式中，获取模块1501可以接收接收端发送的频偏参数。获取模块1501用于执行的操作可以参考上述S104中与发送端相关的内容。此时，频偏参数可以由接收端根据业务信号的频谱信息确定。并且，在获取模块1501接收接收端发送的频偏参数之前，发送端还可以利用发送模块向发送端发送上述业务信号。
在该第一种可选方式中，通信装置还包括接收模块(图15中未示出)和预补偿模块(图15中未示出)，接收模块可以用于接收接收端发送的频谱信息，预补偿模块可以用于根据该频谱信息对后续待发送的业务信号进行预补偿。
需要说明的是，接收端可以在所述业务信号的频偏程度小于或等于频偏程度阈值时，向所述发送端发送所述频谱信息。业务信号在传输过程中受到的影响包括：由于业务信号频偏所带来的滤波器对业务信号滤波的第一影响，以及除第一影响之外的第二影响(如发送端和接收端上光电器件对业务信号滤波带来的影响，以及在业务信号未频偏时滤波器对业务信号滤波所带来的影响)。在业务信号的频偏程度小于频偏程度阈值时，第一影响可以忽略不计，此时频谱信息主要反映上述第二影响。因此，在业务信号的频偏程度小于频偏程度阈值时，接收端可以将业务信号的频谱信息反馈给发送端，以便于发送端根据该频谱信息对业务信号进行预补偿，以消除上述第二影响，进一步降低滤波代价。
在获取模块1501获取频偏参数的第二种可选方式中，获取模块1501可以接收接收端发送的业务信号的频谱信息，并根据该频谱信息确定该频偏参数。此时，发送端在接收接收端发送的频谱信息之前，发送端还可以利用发送模块(图15中未示出)向发送端发送上述业务信号。获取模块根据频谱信息确定该频偏参数的过程可以参考接收端根据频谱信息确定频偏 参数的过程，本申请在此不做赘述。
上述频偏参数可以用于指示偏移量大小和偏移方向中的至少一种参数。当频偏参数未能指示偏移量大小和偏移方向中的一种参数时，获取模块需要采用其他方式确定这种参数。
示例地，在频偏参数用于指示该偏移方向，且不用于指示偏移量大小时，获取模块1501可以根据该偏移方向确定发送端的中心频率的调节方向，并且获取模块1501还可以获取发送端的中心频率的调节量大小。该调节量大小可以预先配置在获取模块中，也可以由获取模块随机生成，也可以由其他设备发送给获取模块，本申请对此不作限定。
又示例地，在频偏参数用于指示该偏移量大小，且不用于指示偏移方向时，获取模块1501可以将该偏移量大小作为发送端的中心频率的调节量大小，并且获取模块1501还可以获取发送端的中心频率的调节方向。该调节方向可以预先配置在获取模块1501中，也可以由获取模块1501随机生成，也可以由其他设备发送给获取模块1501，本申请对此不作限定。并且，在调节模块1502每次调节发送端的中心频率之后，获取模块1501可以再次获取频偏参数(如接收发送端发送的频偏参数)，并判断该频偏参数所指示的偏移量大小是否减小。如果频偏参数所指示的偏移量大小减小，说明调节模块1502对发送端的中心频率的调节方向是正确的，后续可以继续向该调节方向调节发送端的中心频率。如果频偏参数所指示的偏移量大小增大，说明调节模块1502对发送端的中心频率的调节方向是错误的，后续调节模块1502可以改变其中心频率的调节方向，以向相反的方向调节发送端的中心频率。
可选地，调节模块1502可以在调节发送端的中心频率之前，可以对业务信号的频偏程度是否大于频偏程度阈值进行判断，并在确定业务信号的频偏程度大于频偏程度阈值时，才调节发送端的中心频率。在业务信号的频偏程度小于或等于频偏程度阈值时，调节模块1502无需对其中心频率进行调节。
调节模块1502对业务信号的频偏程度是否大于频偏程度阈值进行判断的方式多种多样，以下将以其中的两种可实现方式为例进行讲解。
在第一种可实现方式中，频偏参数用于指示上述偏移量大小，此时，调节模块1502判断频偏程度是否大于频偏程度阈值的过程，可以参考接收端根据偏移量大小判断频偏程度是否大于频偏程度阈值的过程，本申请在此不作赘述。
在第二种可实现方式中，接收端发送的频偏参数(或频谱信息)包括谱估计系数的虚部。调节模块1502可以根据谱估计系数的虚部对业务信号的频偏程度是否大于频偏程度阈值进行判断。调节模块1502根据谱估计系数的虚部判断频偏程度是否大于频偏程度阈值的过程，可以参考接收端根据谱估计系数的虚部判断频偏程度是否大于频偏程度阈值的过程，本申请在此不作赘述。
在发送端和接收端均对业务信号的频偏程度是否大于频偏程度阈值进行判断时，通过发送端和接收端的双重判断，提升了判断结果的准确度。
本申请实施例还提供了一种通信系统，该通信系统包括：发送端和接收端。该发送端包括本申请实施例提供的任一种用于发送端的通信装置(如图14所示的通信装置)；接收端包括本申请实施例提供的任一种用于接收端的通信装置(如图15所示的通信装置)。
在本申请中，术语“第一”和“第二”等仅用于描述目的，而不能理解为指示或暗示相对重要性。术语“至少一个”指一个或多个，“多个”指两个或两个以上，除非另有明确的 限定。术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。
本申请实施例提供的方法实施例和装置实施例等不同类型的实施例均可以相互参考，本申请实施例对此不做限定。本申请实施例提供的方法实施例操作的先后顺序能够进行适当调整，操作也能够根据情况进行相应增减，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化的方法，都应涵盖在本申请的保护范围之内，因此不再赘述。
在本申请提供的相应实施例中，应该理解到，所揭露的系统和装置等可以通过其它的构成方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，模块的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个模块可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元描述的部件可以是或者也可以不是物理单元，既可以位于一个地方，或者也可以分布到多个装置上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
以上所述，仅为本申请的可选实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (37)

  1. 一种通信方法，其特征在于，用于接收端，所述接收端与发送端通过光纤连接，所述光纤上设置有至少一个滤波器，所述方法包括：
    接收所述发送端发送的业务信号；
    获取所述业务信号的频谱信息；
    根据所述频谱信息，向所述发送端发送所述业务信号的频偏参数；
    其中，所述频偏参数用于指示：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。
  2. 根据权利要求1所述的方法，其特征在于，所述频谱信息包括：信道响应。
  3. 根据权利要求1所述的方法，其特征在于，所述频谱信息包括：谱估计系数。
  4. 根据权利要求2所述的方法，其特征在于，在向所述发送端发送所述业务信号的频偏参数之前，所述方法还包括：
    对所述信道响应进行快速傅立叶变换，得到频域响应；
    根据所述频域响应和所述业务信号的波特率，得到所述频偏参数。
  5. 根据权利要求4所述的方法，其特征在于，所述信道响应包括N个采样点，N表示所述快速傅里叶变换的点数；所述频域响应包括所述业务信号在N个频率下的功率，且所述N个采样点与所述N个频率一一对应，所述业务信号在每个所述频率下的功率经过对应的采样点变换得到；
    根据所述频域响应和所述业务信号的波特率，得到所述频偏参数，包括：
    根据频偏公式，得到所述频偏参数；
    其中，所述频偏公式包括：f＝(N/2-M)*F/N；f表示所述频偏参数；M表示功率最小的所述频率对应的采样点的索引；F表示所述业务信号的波特率。
  6. 根据权利要求3所述的方法，其特征在于，在向所述发送端发送所述业务信号的频偏参数之前，所述方法还包括：
    根据所述频谱信息确定所述谱估计系数的虚部；
    根据所述谱估计系数的虚部的正负确定所述频偏参数，所述至少一种信息包括所述偏移方向。
  7. 根据权利要求3所述的方法，其特征在于，在向所述发送端发送所述业务信号的频偏参数之前，所述方法还包括：
    根据所述频谱信息确定所述谱估计系数的虚部；
    根据所述谱估计系数的虚部确定所述频偏参数，所述至少一种信息包括所述偏移方向，所述频偏参数还用于指示所述谱估计系数的虚部的绝对值。
  8. 根据权利要求1至7任一所述的方法，其特征在于，在向所述发送端发送所述业务信号的频偏参数之前，所述方法还包括：
    确定所述业务信号的频偏程度大于频偏程度阈值，所述业务信号的频偏程度为：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的频偏程度。
  9. 根据权利要求8所述的方法，其特征在于，所述至少一种信息包括所述偏移量大小，确定所述业务信号的频偏程度大于频偏程度阈值，包括：
    在所述偏移量大小大于偏移量大小阈值时，确定所述业务信号的频偏程度大于频偏程度阈值。
  10. 根据权利要求3、6或7所述的方法，其特征在于，在向所述发送端发送所述业务信号的频偏参数之前，所述方法还包括：
    在所述谱估计系数的虚部的绝对值大于绝对值阈值时，确定所述业务信号的频偏程度大于频偏程度阈值。
  11. 根据权利要求1至10任一所述的方法，其特征在于，获取所述业务信号的频谱信息，包括：
    对所述业务信号进行均衡处理；
    根据所述均衡处理后的所述业务信号，获取所述频谱信息。
  12. 根据权利要求1至11任一所述的方法，其特征在于，所述方法还包括：
    在所述业务信号的频偏程度小于或等于频偏程度阈值时，向所述发送端发送所述频谱信息。
  13. 根据权利要求12所述的方法，其特征在于，所述方法包括：
    在获取所述业务信号的谱估计系数后，根据第一频率更新所述谱估计系数中的实部，以更新所述谱估计系数；
    根据当前的所述谱估计系数，对所述业务信号进行滤波；
    在第一条件满足时，降低所述第一频率，所述第一条件包括：所述接收端向所述发送端发送所述频谱信息。
  14. 根据权利要求13所述的方法，其特征在于，所述第一条件还包括：所述实部的绝对值小于第一阈值。
  15. 根据权利要求1至14任一所述的方法，其特征在于，所述方法包括：
    在获取所述业务信号的谱估计系数后，根据第二频率更新所述谱估计系数中的虚部，以更新所述谱估计系数；
    根据当前的所述谱估计系数，对所述业务信号进行滤波；
    在第二条件满足时，降低所述第二频率，所述第二条件包括：所述接收端向所述发送端发送所述频偏参数。
  16. 根据权利要求15所述的方法，其特征在于，所述第二条件还包括：所述虚部的绝对值小于第二阈值。
  17. 一种通信方法，其特征在于，用于发送端，所述发送端与接收端通过光纤连接，所述光纤上设置有至少一个滤波器，所述方法包括：
    获取业务信号的频偏参数，所述频偏参数用于指示：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息；所述频偏参数是根据所述业务信号的频谱信息确定的参数；
    根据所述频偏参数所指示的所述至少一种信息，调节所述发送端的中心频率。
  18. 根据权利要求17所述的方法，其特征在于，所述调节所述发送端的中心频率，包括：
    调节所述发送端中数字信号的频率和激光器的工作频率中的至少一种频率，以调节所述发送端的中心频率。
  19. 一种通信装置，其特征在于，用于接收端，所述接收端与发送端通过光纤连接，所述 光纤上设置有至少一个滤波器，所述通信装置包括：
    接收模块，用于接收所述发送端发送的业务信号；
    获取模块，用于获取所述业务信号的频谱信息；
    第一发送模块，用于根据所述频谱信息，向所述发送端发送所述业务信号的频偏参数；
    其中，所述频偏参数用于指示：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息。
  20. 根据权利要求18所述的装置，其特征在于，所述频谱信息包括：信道响应。
  21. 根据权利要求18所述的装置，其特征在于，所述频谱信息包括：谱估计系数。
  22. 根据权利要求20所述的装置，其特征在于，所述通信装置还包括：
    第一处理模块，用于对所述信道响应进行快速傅立叶变换，得到频域响应；
    第二处理模块，用于根据所述频域响应和所述业务信号的波特率，得到所述频偏参数。
  23. 根据权利要求22所述的装置，其特征在于，所述信道响应包括N个采样点，N表示所述快速傅里叶变换的点数；所述频域响应包括所述业务信号在N个频率下的功率，且所述N个采样点与所述N个频率一一对应，所述业务信号在每个所述频率下的功率经过对应的采样点变换得到；
    所述第二处理模块用于：根据频偏公式，得到所述频偏参数；
    其中，所述频偏公式包括：f＝(N/2-M)*F/N；f表示所述频偏参数；M表示功率最小的所述频率对应的采样点的索引；F表示所述业务信号的波特率。
  24. 根据权利要求21所述的装置，其特征在于，所述通信装置还包括：
    第一确定模块，用于根据所述频谱信息确定所述谱估计系数的虚部；
    第二确定模块，用于根据所述谱估计系数的虚部的正负确定所述频偏参数，所述至少一种信息包括所述偏移方向。
  25. 根据权利要求21所述的装置，其特征在于，所述通信装置还包括：
    第三确定模块，用于根据所述频谱信息确定所述谱估计系数的虚部；
    第四确定模块，用于根据所述谱估计系数的虚部确定所述频偏参数，所述至少一种信息包括所述偏移方向，所述频偏参数还用于指示所述谱估计系数的虚部的绝对值。
  26. 根据权利要求19至25任一所述的装置，其特征在于，所述通信装置还包括：
    第五确定模块，用于确定所述业务信号的频偏程度大于频偏程度阈值，所述业务信号的频偏程度为：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的频偏程度。
  27. 根据权利要求26所述的装置，其特征在于，所述至少一种信息包括所述偏移量大小，所述第五确定模块用于：
    在所述偏移量大小大于偏移量大小阈值时，确定所述业务信号的频偏程度大于频偏程度阈值。
  28. 根据权利要求21、24或25所述的装置，其特征在于，所述通信装置还包括：
    第六确定模块，用于在所述谱估计系数的虚部的绝对值大于绝对值阈值时，确定所述业务信号的频偏程度大于频偏程度阈值。
  29. 根据权利要求19至28任一所述的装置，其特征在于，所述获取模块用于：
    对所述业务信号进行均衡处理；
    根据所述均衡处理后的所述业务信号，获取所述频谱信息。
  30. 根据权利要求19至29任一所述的装置，其特征在于，所述通信装置还包括：
    第二发送模块，用于在所述业务信号的频偏程度小于或等于频偏程度阈值时，向所述发送端发送所述频谱信息。
  31. 根据权利要求30所述的装置，其特征在于，所述通信装置包括：
    第一更新模块，用于在获取所述业务信号的谱估计系数后，根据第一频率更新所述谱估计系数中的实部，以更新所述谱估计系数；
    第一滤波模块，用于根据当前的所述谱估计系数，对所述业务信号进行滤波；
    第一降低模块，用于在第一条件满足时，降低所述第一频率，所述第一条件包括：所述接收端向所述发送端发送所述频谱信息。
  32. 根据权利要求31所述的装置，其特征在于，所述第一条件还包括：所述实部的绝对值小于第一阈值。
  33. 根据权利要求19至32任一所述的装置，其特征在于，所述通信装置包括：
    第二更新模块，用于在获取所述业务信号的谱估计系数后，根据第二频率更新所述谱估计系数中的虚部，以更新所述谱估计系数；
    第二滤波模块，用于根据当前的所述谱估计系数，对所述业务信号进行滤波；
    第二降低模块，用于在第二条件满足时，降低所述第二频率，所述第二条件包括：所述接收端向所述发送端发送所述频偏参数。
  34. 根据权利要求33所述的装置，其特征在于，所述第二条件还包括：所述虚部的绝对值小于第二阈值。
  35. 一种通信装置，其特征在于，用于发送端，所述发送端与接收端通过光纤连接，所述光纤上设置有至少一个滤波器，所述通信装置包括：
    获取模块，用于获取业务信号的频偏参数，所述频偏参数用于指示：所述业务信号的中心频率相对所述至少一个滤波器的中心频率的偏移量大小和偏移方向中的至少一种信息；所述频偏参数是根据所述业务信号的频谱信息确定的参数；
    调节模块，用于根据所述频偏参数所指示的所述至少一种信息，调节所述发送端的中心频率。
  36. 根据权利要求35所述的装置，其特征在于，所述调节模块用于：
    调节所述发送端中数字信号的频率和激光器的工作频率中的至少一种频率，以调节所述发送端的中心频率。
  37. 一种通信系统，其特征在于，包括：发送端和接收端；
    所述发送端包括权利要求19至34任一所述的通信装置；
    所述接收端包括权利要求35或36任一所述的通信装置。
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US20050271394A1 (en) * 2004-06-02 2005-12-08 James Whiteaway Filter to improve dispersion tolerance for optical transmission
CN106792281A (zh) * 2015-11-20 2017-05-31 上海贝尔股份有限公司 光线路终端及光网络单元
JP2018133720A (ja) * 2017-02-16 2018-08-23 富士通株式会社 光伝送装置および波長ずれ検出方法
US20200036446A1 (en) * 2018-07-25 2020-01-30 Fujitsu Limited Optical transmission device and optical transmission system

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Publication number Priority date Publication date Assignee Title
US20050271394A1 (en) * 2004-06-02 2005-12-08 James Whiteaway Filter to improve dispersion tolerance for optical transmission
CN106792281A (zh) * 2015-11-20 2017-05-31 上海贝尔股份有限公司 光线路终端及光网络单元
JP2018133720A (ja) * 2017-02-16 2018-08-23 富士通株式会社 光伝送装置および波長ずれ検出方法
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