WO2016149901A1 - 一种非线性补偿的调制方法、装置以及光发射机 - Google Patents

一种非线性补偿的调制方法、装置以及光发射机 Download PDF

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Publication number
WO2016149901A1
WO2016149901A1 PCT/CN2015/074917 CN2015074917W WO2016149901A1 WO 2016149901 A1 WO2016149901 A1 WO 2016149901A1 CN 2015074917 W CN2015074917 W CN 2015074917W WO 2016149901 A1 WO2016149901 A1 WO 2016149901A1
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Prior art keywords
subcarriers
signal
subcarrier
optical
time domain
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PCT/CN2015/074917
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English (en)
French (fr)
Inventor
毛邦宁
李良川
王轲
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华为技术有限公司
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Priority to PCT/CN2015/074917 priority Critical patent/WO2016149901A1/zh
Priority to CN201580078201.6A priority patent/CN107431681B/zh
Publication of WO2016149901A1 publication Critical patent/WO2016149901A1/zh

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    • 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
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
    • H04B10/2543—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to fibre non-linearities, e.g. Kerr effect
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems

Definitions

  • the present invention relates to the field of communications technologies, and in particular, to a nonlinear compensation modulation method and apparatus, and an optical transmitter.
  • phase-conjugated XY dual polarization transmission system in which data transmitted and its complex conjugate data are respectively modulated onto two orthogonal polarizations, at the receiving end, through signal processing techniques. After carrier recovery, the Y-polarized data is conjugated and then added to the X-polarized data to reduce nonlinear phase noise.
  • the system can get rid of the demand for hardware such as pump laser source and high nonlinear fiber, since the signal in the Y polarization direction is the conjugate of the X direction signal, the actual transmission capacity is reduced by half, resulting in an increase in overhead.
  • Embodiments of the present invention provide a nonlinear compensation modulation method and apparatus, and an optical transmitter, which can improve transmission capacity during optical communication and reduce overhead.
  • a first aspect of the present invention provides a nonlinear compensation modulation method, including:
  • phase conjugate pair calculates nonlinear phase noise for phase compensation.
  • the preset number of empty subcarriers is set in a plurality of first subcarriers, and the first digital signal is modulated onto the plurality of first subcarriers, and the second digit is The signal is modulated onto a plurality of second subcarriers, including:
  • a frequency of each of the plurality of first subcarriers and the multiple The frequencies of the second subcarriers in the two subcarriers are respectively equal to each other;
  • the preset number of the null subcarriers is less than or equal to half of the total number of the plurality of first subcarriers
  • the null subcarrier Before the phase conjugate value is modulated to the null subcarrier, the null subcarrier does not carry a modulated signal, or the modulated signal carried by the null subcarrier is redundant data;
  • the phase conjugate value carried by the null subcarrier is calculated by calculating a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located. of.
  • the modulating the multiple target first subcarriers and the multiple second subcarriers onto an optical carrier, and transmitting the optical carrier To the optical receiver including:
  • An optical carrier carrying the polarization-multiplexed first optical signal and the second optical signal is transmitted to the optical receiver.
  • the converting, by the first subcarrier, the modulated signal carried by the target first subcarrier into the first a serial time domain signal, and converting the modulated signal carried by each of the plurality of second subcarriers into a second serial time domain signal specifically:
  • the modulated signal carried by one subcarrier is converted into a first serial time domain signal
  • the modulated signal carried by each second subcarrier is converted into a second serial time domain signal.
  • a second aspect of the present invention provides a non-linearly compensated modulation apparatus, comprising:
  • a first modulation module configured to set a preset number of empty subcarriers in the plurality of first subcarriers, and The first digital signal is modulated onto the plurality of first subcarriers, and the second digital signal is modulated onto the plurality of second subcarriers; wherein the first digital signal is not modulated onto the null subcarrier;
  • a calculation module configured to calculate a phase conjugate value of the modulated signal carried by the second subcarrier at a frequency at which the null subcarrier is located, and notify the first modulation module to modulate the phase conjugate value to a corresponding frequency Determining an empty subcarrier, and using the plurality of first subcarriers as a plurality of target first subcarriers;
  • a second modulation module configured to modulate the plurality of target first subcarriers and the plurality of second subcarriers onto an optical carrier, and transmit the optical carrier to an optical receiver to enable the optical receiving
  • the machine calculates nonlinear phase noise based on the phase conjugate pair in the optical carrier for phase compensation.
  • the first modulation module includes:
  • a setting unit configured to select a preset number of first subcarriers among the plurality of first subcarriers, and set the selected preset number of first subcarriers as null subcarriers;
  • a modulating unit configured to modulate the first digital signal to a first subcarrier of the plurality of first subcarriers that is not set to the null subcarrier, and modulate the second digital signal to the plurality of second subcarriers .
  • the frequency of each of the plurality of first subcarriers is equal to the frequency of each of the plurality of second subcarriers
  • the preset number of the null subcarriers is less than or equal to half of the total number of the plurality of first subcarriers
  • the null subcarrier Before the phase conjugate value is modulated to the null subcarrier, the null subcarrier does not carry a modulated signal, or the modulated signal carried by the null subcarrier is redundant data;
  • the phase conjugate value carried by the null subcarrier is calculated by calculating a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located. of.
  • the second modulation module includes:
  • a time domain signal conversion unit configured to convert a modulated signal carried by each target first subcarrier of the plurality of target first subcarriers into a first serial time domain signal, and the plurality of second subcarriers In each The modulated signal carried by the two subcarriers is converted into a second serial time domain signal;
  • An electrical signal conversion unit configured to convert the first serial time domain signal into a first analog electrical signal, and convert the second serial time domain signal into a second analog electrical signal;
  • An optical signal modulating unit configured to modulate the first analog electrical signal and the second analog electrical signal onto a same optical carrier to obtain a first optical signal and a second optical signal, and to the first optical And multiplexing the signal and the second optical signal;
  • a transmitting unit configured to transmit the optical carrier carrying the polarization multiplexed first optical signal and the second optical signal to the optical receiver.
  • the time domain signal conversion unit is configured to perform fast Fourier inverse on each of the target first subcarriers and the second subcarriers of the plurality of second subcarriers, respectively. Transforming and parallel-to-serial conversion, converting the modulated signal carried by the first subcarrier of each target into a first serial time domain signal, and converting the modulated signal carried by each second subcarrier into a second serial time domain signal ;or,
  • the time domain signal conversion unit is configured to separately perform upsampling subcarrier modulation on each of the target first subcarriers and the second subcarriers of the plurality of second subcarriers Adding to the time domain, converting the modulated signal carried by the first subcarrier of each target into a first serial time domain signal, and converting the modulated signal carried by each second subcarrier into a second serial time domain signal .
  • a third aspect of the present invention provides an optical transmitter, including: a first modulating device, a processor, and a second modulating device;
  • the first modulating device is configured to set a preset number of empty subcarriers in the plurality of first subcarriers, and modulate the first digital signal to the plurality of first subcarriers, and modulate the second digital signal to a plurality of second subcarriers; wherein the first digital signal is not modulated onto the null subcarrier;
  • the processor is configured to calculate a phase conjugate value of a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located, and notify the first modulating device to modulate the phase conjugate value to a corresponding frequency And the plurality of first subcarriers are used as the plurality of target first subcarriers;
  • the second modulating means is configured to use the plurality of target first subcarriers and the plurality of second subcarriers
  • the waves are modulated onto an optical carrier and the optical carrier is transmitted to an optical receiver such that the optical receiver calculates nonlinear phase noise based on phase conjugate pairs in the optical carrier for phase compensation.
  • the first modulating device is configured to select a preset number of first subcarriers among the plurality of first subcarriers, and select the preset number of first subcarriers
  • the carrier is set to a null subcarrier, and modulates the first digital signal to a first subcarrier of the plurality of first subcarriers that is not set to the null subcarrier, and modulates the second digital signal to the plurality of second subcarriers On the carrier.
  • the frequency of each of the plurality of first subcarriers is equal to the frequency of each of the plurality of second subcarriers
  • the preset number of the null subcarriers is less than or equal to half of the total number of the plurality of first subcarriers
  • the null subcarrier Before the phase conjugate value is modulated to the null subcarrier, the null subcarrier does not carry a modulated signal, or the modulated signal carried by the null subcarrier is redundant data;
  • the phase conjugate value carried by the null subcarrier is calculated by calculating a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located. of.
  • the second modulating apparatus specifically includes: Time domain signal converter, digital to analog converter, quadrature modulator, polarization combiner;
  • the time domain signal converter is configured to convert a modulated signal carried by each target first subcarrier of the plurality of target first subcarriers into a first serial time domain signal, and the plurality of second The modulated signal carried by each second subcarrier in the subcarrier is converted into a second serial time domain signal;
  • the digital-to-analog converter is configured to convert the first serial time domain signal into a first analog electrical signal, and convert the second serial time domain signal into a second analog electrical signal;
  • the quadrature modulator is configured to modulate the first analog electrical signal and the second analog electrical signal onto a same optical carrier to obtain a first optical signal and a second optical signal;
  • the polarization combiner is configured to perform polarization reconstruction on the first optical signal and the second optical signal And transmitting, by the optical carrier carrying the polarization-multiplexed first optical signal and the second optical signal to the optical receiver.
  • the time domain signal converter is specifically configured to perform fast Fourier inverse on each of the target first subcarriers and the second subcarriers of the plurality of second subcarriers, respectively Transforming and parallel-to-serial conversion, converting the modulated signal carried by the first subcarrier of each target into a first serial time domain signal, and converting the modulated signal carried by each second subcarrier into a second serial time domain signal ;or,
  • the time domain signal converter is configured to separately perform upsampling subcarrier modulation on each of the target first subcarriers and the second subcarriers of the plurality of second subcarriers Adding to the time domain, converting the modulated signal carried by the first subcarrier of each target into a first serial time domain signal, and converting the modulated signal carried by each second subcarrier into a second serial time domain signal .
  • the embodiment of the present invention sets a preset number of empty subcarriers in the plurality of first subcarriers, so that the first digital signal is not modulated on the set null subcarrier, and then calculates the frequency of the null subcarrier.
  • the phase conjugate value of the modulated signal carried by the two subcarriers, and the phase conjugate value is modulated onto the corresponding null subcarrier, so that the null subcarrier added with the phase conjugate value and the second subcarrier corresponding to the position form a phase
  • the yoke pair enables the optical receiver to calculate the nonlinear phase noise according to the phase conjugate pair in the optical carrier for phase compensation.
  • the signals in the Y polarization direction are conjugates of the X direction signals, so the actual transmission capacity can be increased to reduce the overhead.
  • FIG. 1 is a schematic flow chart of a nonlinear compensation modulation method according to an embodiment of the present invention
  • 1a is a schematic structural diagram of a subcarrier provided by an embodiment of the present invention.
  • FIG. 2 is a schematic flow chart of another nonlinear compensation modulation method according to an embodiment of the present invention.
  • FIG. 3 is a schematic structural diagram of a nonlinear compensation modulation apparatus according to an embodiment of the present invention.
  • FIG. 4 is a schematic structural diagram of a first modulation module according to an embodiment of the present invention.
  • FIG. 5 is a schematic structural diagram of a second modulation module according to an embodiment of the present disclosure.
  • FIG. 6 is a schematic structural diagram of an optical transmitter according to an embodiment of the present invention.
  • FIG. 7 is a schematic structural diagram of another optical transmitter according to an embodiment of the present invention.
  • FIG. 8 is a schematic structural diagram of still another optical transmitter according to an embodiment of the present invention.
  • FIG. 1 is a schematic flowchart of a nonlinear compensation modulation method according to an embodiment of the present invention.
  • the method may include:
  • the optical transmitter when the first digital signal and the second digital signal are input to the optical transmitter, the optical transmitter first sets a preset number of empty subcarriers in the plurality of first subcarriers, and the set null subcarrier is reserved.
  • the null subcarriers are out and the first digital signal modulation is not allowed to be mapped thereto, that is, the first digital signal is not modulated onto the set null subcarriers when subcarrier mapping is performed subsequently, wherein the number of null subcarriers is set. It is less than or equal to half of the total number of the plurality of first subcarriers, and the number of empty subcarriers set may not be less than one.
  • the first digital signal may be modulated onto the plurality of first subcarriers, and the second digital signal may be modulated onto the plurality of second subcarriers, wherein the first The digital signal is not modulated onto the set null subcarrier.
  • the plurality of first subcarriers may be used as a first group of subcarriers, and the plurality of second subcarriers may be used as a second Group subcarriers.
  • the optical transmitter Before modulating the first digital signal and the second digital signal to corresponding subcarriers, the optical transmitter first serially and serially exchanges the first digital signal and the second digital signal, and Converting the first digital signal and the second digital signal into parallel frequency domain data, and then performing QAM (quadrature amplitude modulation, on the first digital signal and the second digital signal that have become parallel frequency domain data, Quadrature Amplitude Modulation) maps the binary bit stream onto the complex plane and becomes a modulation symbol. The next step is to map the modulation symbol to the corresponding subcarrier, that is, to modulate the first digital signal into the Decoding the second digital signal onto the plurality of second subcarriers on the plurality of first subcarriers.
  • QAM quadrature amplitude modulation
  • S102 Calculate a phase conjugate value of a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located, and modulate the phase conjugate value to the null subcarrier of a corresponding frequency, and
  • the first subcarriers serve as a plurality of target first subcarriers;
  • the optical transmitter may store all subcarriers, and then extract the set from the stored subcarriers.
  • the frequency of each of the plurality of first subcarriers is equal to the frequency of each of the plurality of second subcarriers, for example, if there are three first subcarriers and 3 second subcarriers, then the first subcarrier and the second subcarrier at the first location are respectively at the same frequency, and the frequencies of the first subcarrier and the second subcarrier at the second location are respectively Similarly, the first subcarrier and the second subcarrier at the third location are respectively at the same frequency.
  • IFFT inverse fast Fourier transform
  • the modulation signal z carried by the first subcarrier X1 and the modulation signal y carried by the second subcarrier Y1 form a phase conjugate pair.
  • the null subcarrier does not carry a modulated signal, or the modulated signal carried by the null subcarrier is redundant data; and the phase conjugate value
  • the phase conjugate value carried by the null subcarrier is calculated by calculating a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located.
  • each of the plurality of target first subcarriers and the plurality of second subcarriers may be separately Performing fast Fourier transform and parallel-to-serial conversion on each second subcarrier in the carrier, and converting the modulated signal carried by the first subcarrier of each target into a first serial time domain signal, and each second subcarrier is Transmitting the carried modulated signal into a second serial time domain signal, and then inserting a CP (Cyclic Prefix) into the first serial time domain signal and the second serial time domain signal, respectively, and inserting the CP into the CP
  • the first serial time domain signal is converted into a first analog electrical signal
  • the second serial time domain signal inserted into the CP is converted into a second analog electrical signal; and finally the first analog electrical signal and the first analog electrical signal are
  • the second analog electrical signal is modulated onto the same optical carrier to obtain a first optical signal and a second optical signal, and the first optical signal and the second optical
  • each of the plurality of target first subcarriers and the plurality of second subcarriers may be separately Each The second subcarrier performs upsampling subcarrier modulation and time domain addition, and converts the modulated signal carried by each target first subcarrier into a first serial time domain signal, and modulates the second subcarrier Converting the signal into a second serial time domain signal, converting the first serial time domain signal into a first analog electrical signal, converting the second serial time domain signal into a second analog electrical signal; Modulating the first analog electrical signal and the second analog electrical signal onto a same optical carrier to obtain a first optical signal and a second optical signal, and to the first optical signal and the second optical
  • the signals are polarization multiplexed such that the first optical signal and the second optical signal can be in different polarization states, respectively.
  • FIG. 1 is a schematic structural diagram of a subcarrier according to an embodiment of the present invention. As shown in FIG. 1a, the first digital signal is Y, the second digital signal is X, and X1 to X9 are multiple second subcarriers.
  • Y1 to Y9 are 9 subcarriers of the plurality of first subcarriers, wherein Y2, Y5, Y8 are three empty subcarriers set in advance; when X and Y are input to the optical transmitter,
  • the optical transmitter may separately map and map the partial X to X1 to X9 of the plurality of second subcarriers, and simultaneously modulate the partial Y modulation to Y1, Y3, Y4, Y6 of the plurality of first subcarriers, respectively.
  • the optical transmitter is reselected Extracting the second subcarrier of the frequency at which the null subcarrier is located, extracting X2, X5, and X8, and calculating the phase conjugate values of the modulated signals carried by X2, X5, and X8, respectively, and conjugate the calculated phase
  • the value is modulated onto the corresponding null subcarrier, that is, the phase conjugate value of X2 is modulated to Y2, and the X5 is
  • the bit conjugate value is modulated onto Y5, the phase conjugate value of X8 is modulated onto Y8, and the first subcarrier of Y1 to Y9 is used as the target first subcarrier, that is, Y2 in the target first subcarrier.
  • the modulated signals in Y5 and Y8 all become phase conjugate values of the modulated signals carried by the corresponding second subcarriers.
  • the optical transmitter then modulates the target first subcarrier and the second subcarrier onto an optical carrier, respectively, and transmits the optical carrier to an optical receiver, such that the optical receiver is Phase conjugate pairs in the optical carrier calculate nonlinear phase noise for phase compensation.
  • the optical receiver receives the optical front end by coherently, and the optical signal becomes an electrical signal, which is converted into a digital signal by an ADC (Analog-to-Digital Converter), and then passes through After clock recovery, dispersion compensation, and carrier recovery, the frequency-division multiplexed signals with phase noise are restored, such as X2 and Y2 sub-frequency.
  • ADC Analog-to-Digital Converter
  • phase noise term arg(exp(j ⁇ )*exp(j ⁇ ))/2, and then according to arg( The value of exp(j ⁇ )*exp(j ⁇ ))/2 eliminates the phase noise term of X1, X2, X3, Y1, Y3, thereby improving the quality of the signal, ie Six subcarriers in a subcarrier is redundant, so that overhead can be reduced to 20%.
  • the setting of the null subcarrier in the embodiment of the present invention is not limited to the mode of FIG. 1a, and the optical transmitter may only set a preset number of null subcarriers in multiple first subcarriers, or may only be in multiple second subcarriers.
  • Setting a preset number of empty subcarriers in the first subcarrier, and setting a second preset number of null subcarriers in the plurality of second subcarriers The implementation process also constructs a phase conjugate pair through the null subcarriers, so that the optical receiver can calculate the phase noise term according to the phase conjugate pair to phase compensate each subcarrier.
  • the modulation signal in the subcarriers having the same frequency as the null subcarrier is not zero and is not redundant data, and the number of total null subcarriers is less than or equal to half of the total number of the plurality of first subcarriers,
  • the quality of the signal can be improved and the overhead can be reduced; wherein the total number of the plurality of first subcarriers is the same as the total number of the plurality of second subcarriers.
  • the embodiment of the present invention sets a preset number of empty subcarriers in the plurality of first subcarriers, so that the first digital signal is not modulated on the set null subcarrier, and then calculates the frequency of the null subcarrier.
  • the phase conjugate value of the modulated signal carried by the two subcarriers, and the phase conjugate value is modulated onto the corresponding null subcarrier, so that the null subcarrier added with the phase conjugate value and the second subcarrier corresponding to the position form a phase
  • the yoke pair enables the optical receiver to calculate the nonlinear phase noise according to the phase conjugate pair in the optical carrier for phase compensation.
  • the signals in the Y polarization direction are conjugates of the X direction signals, so the actual transmission capacity can be increased to reduce the overhead.
  • FIG. 2 it is a flow chart of another nonlinear compensation modulation method according to an embodiment of the present invention. Schematic, the method may include:
  • the optical transmitter when the first digital signal and the second digital signal are input to the optical transmitter, the optical transmitter first sets a preset number of empty subcarriers in the plurality of first subcarriers, and the set null subcarrier is reserved.
  • the null subcarriers are out and the first digital signal modulation is not allowed to be mapped thereto, that is, the first digital signal is not modulated onto the set null subcarriers when subcarrier mapping is performed subsequently, wherein the number of null subcarriers is set. It is less than or equal to half of the total number of the plurality of first subcarriers, and the number of empty subcarriers set may not be less than one.
  • the first digital signal may be modulated onto the plurality of first subcarriers, and the second digital signal may be modulated onto the plurality of second subcarriers, where The first digital signal is not modulated onto the set null subcarrier.
  • the null subcarrier still does not carry a modulated signal, or the modulated signal carried by the null subcarrier is redundant data.
  • the optical transmitter Before modulating the first digital signal and the second digital signal to corresponding subcarriers, the optical transmitter first serially and serially exchanges the first digital signal and the second digital signal, and Converting the first digital signal and the second digital signal into parallel frequency domain data, and then performing QAM mapping on the first digital signal and the second digital signal that have become parallel frequency domain data, and The bit stream is mapped onto the complex plane and becomes a modulation symbol.
  • the modulation symbol can be mapped to the corresponding subcarrier in the next step, that is, the first digital signal is modulated onto the plurality of first subcarriers, and The second digital signal is modulated onto a plurality of second subcarriers.
  • the optical transmitter may store all subcarriers, and then extract from each stored subcarrier. Taking the set null subcarrier and the second subcarrier of the frequency at which the null subcarrier is located.
  • the frequency of each of the plurality of first subcarriers is equal to the frequency of each of the plurality of second subcarriers, for example, if there are three first subcarriers and 3 second subcarriers, then the first subcarrier and the second subcarrier at the first location are respectively at the same frequency, and the frequencies of the first subcarrier and the second subcarrier at the second location are respectively Similarly, the first subcarrier and the second subcarrier at the third location are respectively at the same frequency.
  • the plurality of first subcarriers and the plurality of second subcarriers are respectively obtained by IFFT transform of the same length, it can be ensured that the first subcarrier and the second subcarrier at the same position have the same frequency.
  • the optical transmitter may calculate a phase conjugate value of the modulated signal carried by the second subcarrier at the frequency of the null subcarrier. And modulating the phase conjugate value onto the null subcarrier of the corresponding frequency. For example, an empty subcarrier is X1, and the second subcarrier of the frequency at which the null subcarrier is located is Y1.
  • the null subcarrier does not carry a modulated signal, or the modulated signal carried by the null subcarrier is redundant data; and the phase conjugate value After modulating to the null subcarrier, the phase conjugate value carried by the null subcarrier is calculated by calculating a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located.
  • the plurality of first subcarriers may be used as a plurality of target first subcarriers, that is, the plurality of target first subcarriers.
  • the modulated signals carried by the first subcarriers set to the null subcarriers all become corresponding phase conjugate values.
  • S204 Convert a modulated signal carried by each target first subcarrier of the plurality of target first subcarriers into a first serial time domain signal, and use a second subcarrier of each of the plurality of second subcarriers.
  • the carried modulated signal is converted into a second serial time domain signal;
  • each of the plurality of target first subcarriers and the plurality of second subcarriers may be separately Carrier
  • Each of the second subcarriers performs inverse fast Fourier transform and parallel/serial conversion, and converts the modulated signal carried by the first subcarrier of each target into a first serial time domain signal.
  • each of the plurality of target first subcarriers and the plurality of second subcarriers may be separately
  • Each of the second subcarriers performs upsampling subcarrier modulation and time domain addition, and converts the modulated signal carried by each target first subcarrier into a first serial time domain signal, and carries each second subcarrier The modulated signal is converted to a second serial time domain signal.
  • the optical transmitter obtains the first serial time domain signal and the second serial time domain signal by fast inverse Fourier transform and parallel-serial conversion, respectively, first to the first
  • the serial time domain signal and the second serial time domain signal are inserted into the CP, and the first serial time domain signal inserted into the CP is converted into the first by a DAC (Digital-to-Analog Converter)
  • An analog electrical signal is used to convert the second serial time domain signal inserted into the CP into a second analog electrical signal through the DAC.
  • the optical transmitter obtains the first serial time domain signal and the second serial time domain signal by upsampling subcarrier modulation and time domain addition, the first after inserting the CP directly through the DAC
  • the serial time domain signal is converted into a first analog electrical signal
  • the second serial time domain signal inserted into the CP is converted into a second analog electrical signal by a DAC.
  • the optical transmitter respectively connects the first analog electrical signal and the second analog electrical signal to a quadrature modulator through a driver, and then the first analog power is performed by the orthogonal modulator
  • the signal and the second analog electrical signal are modulated onto the same optical carrier to obtain a first optical signal and a second optical signal, and then the first optical signal and the second optical signal are processed by a polarization combiner Polarization multiplexing allows the first optical signal and the second optical signal to be in different polarization states, respectively.
  • optical carrier carrying the polarization-multiplexed first optical signal and the second optical signal is transmitted to the optical Receiver
  • the polarization combiner transmits a polarization-multiplexed multi-carrier optical signal to the optical receiver.
  • the polarization multiplexed multi-carrier optical signal includes a first optical signal and a second optical signal respectively in different polarization states.
  • the optical receiver receives the optical front end by coherently, the optical signal becomes an electrical signal, is converted into a digital signal by ADC sampling, and then recovered after clock recovery, dispersion compensation, and carrier recovery.
  • Frequency division multiplexed signal of phase noise Taking the X2 and Y2 sub-frequency in Figure 1a as an example, because they have the same frequency and the same amplitude, the nonlinear noise term has a high correlation, and the nonlinear term is expanded into a series and then takes a first-order approximation, which can be considered equal.
  • the embodiment of the present invention sets a preset number of empty subcarriers in the plurality of first subcarriers, so that the first digital signal is not modulated on the set null subcarrier, and then calculates the frequency of the null subcarrier.
  • the phase conjugate value of the modulated signal carried by the two subcarriers, and the phase conjugate value is modulated onto the corresponding null subcarrier, so that the null subcarrier added with the phase conjugate value and the second subcarrier corresponding to the position form a phase
  • the yoke pair enables the optical receiver to calculate the nonlinear phase noise according to the phase conjugate pair in the optical carrier for phase compensation.
  • the signals in the Y polarization direction are conjugates of the X direction signals, so the actual transmission capacity can be increased to reduce the overhead.
  • the nonlinearly compensated modulation apparatus 1 can be used in an optical transmitter, and the nonlinear compensation
  • the modulation device 1 includes: a first modulation module 10, a calculation module 20, and a second modulation module 30;
  • the first modulation module 10 is configured to set a preset number of empty subcarriers in the plurality of first subcarriers, and modulate the first digital signal to the plurality of first subcarriers, and modulate the second digital signal Up to a plurality of second subcarriers; wherein the first digital signal is not modulated onto the null subcarrier;
  • the first modulation module 10 first sets a preset number of empty subcarriers in the plurality of first subcarriers, and the set null subcarrier is The null subcarrier is reserved and the first digital signal modulation is not allowed to be mapped thereto, that is, the first digital signal is not modulated onto the set null subcarrier when the subcarrier mapping is performed subsequently, wherein the set null subcarrier
  • the number is less than or equal to half of the total number of the plurality of first subcarriers, and the number of empty subcarriers set may not be less than one.
  • the first digital signal may be modulated onto the plurality of first subcarriers, and the second digital signal may be modulated onto the plurality of second subcarriers, wherein the first The digital signal is not modulated onto the set null subcarrier.
  • the plurality of first subcarriers may be used as the first group of subcarriers, and the plurality of second subcarriers may be used as the second group of subcarriers.
  • the first modulation module 10 needs to separately serialize the first digital signal and the second digital signal before modulating the first digital signal and the second digital signal to corresponding subcarriers. Exchanging, and converting the first digital signal and the second digital signal into parallel frequency domain data, and then performing QAM mapping on the first digital signal and the second digital signal that have become parallel frequency domain data, and Mapping a binary bit stream onto a complex plane into individual modulation symbols, the next step of mapping the modulation symbols onto corresponding subcarriers, ie, modulating the first digital signal to the plurality of first subcarriers And modulating the second digital signal onto the plurality of second subcarriers.
  • the calculating module 20 is configured to calculate a phase conjugate value of a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located, and notify the first modulation module 10 to modulate the phase conjugate value to Corresponding to the null subcarriers of the frequency, and using the plurality of first subcarriers as a plurality of target first subcarriers;
  • the first digital signal and the second digital signal are used by the first modulation module 10
  • the calculation module 20 may store all the subcarriers, and then extract the set null subcarriers and the second subcarriers of the frequency where the null subcarriers are located from the stored subcarriers.
  • the frequency of each of the plurality of first subcarriers is equal to the frequency of each of the plurality of second subcarriers, for example, if there are three first subcarriers and 3 second subcarriers, then the first subcarrier and the second subcarrier at the first location are respectively at the same frequency, and the frequencies of the first subcarrier and the second subcarrier at the second location are respectively Similarly, the first subcarrier and the second subcarrier at the third location are respectively at the same frequency.
  • the plurality of first subcarriers and the plurality of second subcarriers are respectively obtained by IFFT transform of the same length, it can be ensured that the first subcarrier and the second subcarrier at the same position have the same frequency.
  • the calculating module 20 may calculate a phase conjugate value of the modulated signal carried by the second subcarrier at the frequency of the null subcarrier. And modulating the phase conjugate value onto the null subcarrier of the corresponding frequency.
  • a null subcarrier is X1
  • a second subcarrier of the frequency at which the null subcarrier is located is Y1
  • a modulation signal carried by the second subcarrier Y1 is y.
  • the null subcarrier does not carry a modulated signal, or the modulated signal carried by the null subcarrier is redundant data; and the phase conjugate value After modulating to the null subcarrier, the phase conjugate value carried by the null subcarrier is calculated by calculating a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located.
  • the calculating module 20 may use the plurality of first subcarriers as a plurality of target first subcarriers, that is, the plurality of The modulated signals carried by the first subcarrier set to the null subcarrier in the target first subcarrier all become corresponding phase conjugate values.
  • the second modulation module 30 is configured to modulate the plurality of target first subcarriers and the plurality of second subcarriers onto an optical carrier, and transmit the optical carrier to an optical receiver to enable Optical receiver Calculating nonlinear phase noise according to a phase conjugate pair in the optical carrier for phase compensation;
  • the second modulation module 30 may separately target each of the multiple target first subcarriers. Performing fast inverse Fourier transform and parallel-to-serial conversion on the first subcarrier and each second subcarrier of the plurality of second subcarriers, and converting the modulated signal carried by the first subcarrier of each target into the first serial a time domain signal, and converting the modulated signal carried by each second subcarrier into a second serial time domain signal, and then inserting a CP into the first serial time domain signal and the second serial time domain signal, respectively And converting the first serial time domain signal after the CP is inserted into the first analog electrical signal, converting the second serial time domain signal after the CP is inserted into the second analog electrical signal; and finally the second modulation module 30 And modulating the first analog electrical signal and the second analog electrical signal onto the same optical carrier to obtain a first optical signal and a second optical signal, and to the first optical signal and the
  • the second modulation module 30 may separately target each of the multiple target first subcarriers. Performing upsampling subcarrier modulation and time domain addition on a second subcarrier of each of the plurality of second subcarriers, and converting the modulated signal carried by each target first subcarrier into the first serial a domain signal, and converting the modulated signal carried by each second subcarrier into a second serial time domain signal, and converting the first serial time domain signal into a first analog electrical signal, the second string Converting the time domain signal into a second analog electrical signal; finally, the second modulation module 30 modulates the first analog electrical signal and the second analog electrical signal onto the same optical carrier to obtain the first light
  • the signal and the second optical signal are polarization-multiplexed with the first optical signal and the second optical signal such that the first optical signal and the second optical signal are respectively in different polarization states.
  • the first digital signal is Y
  • the second digital signal is X
  • X1 to X9 are 9 subcarriers of the plurality of second subcarriers
  • Y1 to Y9 are 9 of the plurality of first subcarriers.
  • Subcarriers wherein Y2, Y5, Y8 are three empty subcarriers set in advance; when X and Y are input to the optical transmitter, the first modulation module 10 may separately map and map the partial X to multiple X1 to X9 in the two subcarriers, and simultaneously modulate the partial Y modulation to Y1, Y3, Y4, Y6, Y7, Y9 of the plurality of first subcarriers, wherein the first digital signal is not modulated and mapped to the null Carriers Y2, Y5, and Y8, and the first subcarrier and the second subcarrier of the same column are at the same frequency; the calculation module 20 selects the second subcarrier of the frequency at which the null subcarrier is located, that is, extracts X2.
  • X5, X8, respectively calculate the phase conjugate value of the modulated signal carried by X2, X5, X8, and modulate the calculated phase conjugate value onto the corresponding null subcarrier, that is, the phase conjugate value modulation of X2 On Y2, the phase conjugate value of X5 is modulated onto Y5, and the phase conjugate value of X8 is modulated onto Y8.
  • the first subcarrier of Y1 to Y9 is used as the target first subcarrier, that is, the modulated signals in Y2, Y5, and Y8 in the target first subcarrier become the modulated signals carried by the corresponding second subcarrier. Phase conjugate value.
  • the second modulation module 30 respectively modulates the target first subcarrier and the second subcarrier onto an optical carrier, and transmits the optical carrier to an optical receiver, so that the optical receiver is configured according to A phase conjugate pair in the optical carrier calculates nonlinear phase noise for phase compensation.
  • the optical receiver receives the optical front end by coherently, the optical signal becomes an electrical signal, is converted into a digital signal by ADC sampling, and then recovered after clock recovery, dispersion compensation, and carrier recovery.
  • Frequency-division multiplexed signals of phase noise such as X2 and Y2 sub-frequency
  • the nonlinear noise term has high correlation, and the nonlinear term is expanded into a series and then takes a first-order approximation, which can be considered equal.
  • FIG. 4 is a schematic structural diagram of a first modulation module 10 according to an embodiment of the present invention.
  • the first modulation module 10 includes: a setting unit 101 and a modulation unit 102.
  • the setting unit 101 is configured to select a preset number of first subcarriers among the plurality of first subcarriers, and set the selected preset number of first subcarriers as null subcarriers;
  • the The setting unit 101 sets a preset number of empty subcarriers in the plurality of first subcarriers, and the set null subcarrier is a reserved null subcarrier and does not allow the first digital signal modulation to be mapped thereto, that is, subcarrier mapping is performed subsequently.
  • the first digital signal is not modulated onto the set null subcarrier, wherein the number of null subcarriers set is less than or equal to half of the total number of the plurality of first subcarriers, and the set of null subcarriers The number cannot be less than one.
  • the modulating unit 102 is configured to modulate a first digital signal to a first subcarrier of the plurality of first subcarriers that is not set to the null subcarrier, and modulate the second digital signal to a plurality of second On the subcarrier
  • the modulating unit 102 may modulate the first digital signal to the plurality of first subcarriers, and modulate the second digital signal to multiple And on the second subcarrier, wherein the first digital signal is not modulated on the set null subcarrier.
  • the null subcarrier still does not carry a modulated signal, or the modulated signal carried by the null subcarrier is redundant data.
  • the modulating unit 102 Before modulating the first digital signal and the second digital signal to corresponding subcarriers, the modulating unit 102 first serially and serially exchanges the first digital signal and the second digital signal, and Converting the first digital signal and the second digital signal into parallel frequency domain data, and then performing QAM mapping on the first digital signal and the second digital signal that have become parallel frequency domain data, and The bit stream is mapped onto the complex plane and becomes a modulation symbol.
  • the modulation symbol can be mapped to the corresponding subcarrier in the next step, that is, the first digital signal is modulated onto the plurality of first subcarriers, and The second digital signal is modulated onto a plurality of second subcarriers.
  • FIG. 5 is a schematic structural diagram of a second modulation module 30 according to an embodiment of the present invention.
  • the second modulation module 30 includes: a time domain signal conversion unit 301, an electrical signal conversion unit 302, and light. a signal modulation unit 303, a transmitting unit 304;
  • the time domain signal conversion unit 301 is configured to convert a modulation signal carried by each target first subcarrier of the plurality of target first subcarriers into a first serial time domain signal, and the plurality of The modulated signal carried by each second subcarrier in the two subcarriers is converted into a second serial time domain signal;
  • the time domain signal conversion unit 301 is specifically configured to separately target the first plurality of targets Performing fast inverse Fourier transform and parallel-to-serial conversion on each of the target first subcarriers and the second subcarriers of the plurality of second subcarriers, and converting the modulated signals carried by the first subcarriers of each target into The first serial time domain signal converts the modulated signal carried by each second subcarrier into a second serial time domain signal.
  • the time domain signal converting unit 301 is specifically configured to separately perform upsampling on each of the target first subcarriers and the second subcarriers of the plurality of second subcarriers in the plurality of target first subcarriers Carrier modulation and time domain addition, and converting the modulated signal carried by the first subcarrier of each target into a first serial time domain signal, and converting the modulated signal carried by each second subcarrier into a second serial Domain signal.
  • the electrical signal conversion unit 302 is configured to convert the first serial time domain signal into a first analog electrical signal, and convert the second serial time domain signal into a second analog electrical signal;
  • the time domain signal conversion unit 301 obtains the first serial time domain signal and the second serial time domain signal by fast inverse Fourier transform and parallel-serial conversion
  • the converting unit 302 first inserts the CP into the first serial time domain signal and the second serial time domain signal, respectively, and converts the first serial time domain signal inserted into the CP into the first analog electrical signal through the DAC. And converting the second serial time domain signal after the CP is inserted into the second analog electrical signal through the DAC.
  • the electrical signal conversion unit 302 When the time domain signal conversion unit 301 obtains the first serial time domain signal and the second serial time domain signal by upsampling subcarrier modulation and time domain addition, the electrical signal conversion unit 302 The first serial time domain signal inserted into the CP is directly converted into a first analog electrical signal by a DAC, and the second serial time domain signal inserted into the CP is converted into a second analog electrical signal by a DAC.
  • the optical signal modulating unit 303 is configured to modulate the first analog electrical signal and the second analog electrical signal onto the same optical carrier to obtain a first optical signal and a second optical signal, and The first optical signal and the second optical signal are polarization multiplexed;
  • the optical signal modulating unit 303 respectively connects the first analog electrical signal and the second analog electrical signal to a quadrature modulator through a driver, and then the first through the quadrature modulator
  • the analog electrical signal and the second analog electrical signal are modulated onto the same optical carrier to obtain a first optical signal and a second optical signal, and then the first optical signal and the second light are passed through a polarization combiner
  • the signals are polarization multiplexed such that the first optical signal and the second optical signal are respectively in different polarization states on.
  • the transmitting unit 304 is configured to transmit an optical carrier carrying the polarization multiplexed first optical signal and the second optical signal to an optical receiver;
  • the transmitting unit 304 transmits the polarization-multiplexed multi-carrier optical signal to the polarization combiner to the polarization combiner to In the optical receiver, the polarization multiplexed multi-carrier optical signal includes a first optical signal and a second optical signal respectively in different polarization states.
  • the embodiment of the present invention sets a preset number of empty subcarriers in the plurality of first subcarriers, so that the first digital signal is not modulated on the set null subcarrier, and then calculates the frequency of the null subcarrier.
  • the phase conjugate value of the modulated signal carried by the two subcarriers, and the phase conjugate value is modulated onto the corresponding null subcarrier, so that the null subcarrier added with the phase conjugate value and the second subcarrier corresponding to the position form a phase
  • the yoke pair enables the optical receiver to calculate the nonlinear phase noise according to the phase conjugate pair in the optical carrier for phase compensation.
  • the signals in the Y polarization direction are conjugates of the X direction signals, so the actual transmission capacity can be increased to reduce the overhead.
  • FIG. 6 is a schematic structural diagram of an optical transmitter according to an embodiment of the present invention.
  • the optical transmitter 1000 may include a first modulation device 1002, a processor 1001, and a second modulation device 1003.
  • the number of processors 1001 in 1000 may be one or more, and one processor 1001 is taken as an example in FIG.
  • the first modulation device 1002, the processor 1001, and the second modulation device 1003 may be connected by a communication bus or other means, wherein FIG. 6 is exemplified by a communication bus connection.
  • the first modulating device 1002 is configured to set a preset number of empty subcarriers in the plurality of first subcarriers, and modulate the first digital signal to the plurality of first subcarriers, and modulate the second digital signal Up to a plurality of second subcarriers; wherein the first digital signal is not modulated onto the null subcarrier;
  • the processor 1001 is configured to calculate a phase conjugate value of a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located, and notify the first modulating device 1002 to modulate the phase conjugate value to And corresponding to the null subcarriers of the frequency, and using the plurality of first subcarriers as multiple meshes Marking the first subcarrier;
  • the second modulating device 1003 is configured to modulate the plurality of target first subcarriers and the plurality of second subcarriers onto an optical carrier, and transmit the optical carrier to an optical receiver to enable The optical receiver calculates nonlinear phase noise based on phase conjugate pairs in the optical carrier for phase compensation.
  • the first modulating device 1002 is configured to select a preset number of first subcarriers among the plurality of first subcarriers, and set the selected preset number of first subcarriers as null subcarriers, and Modulating the first digital signal to a first subcarrier of the plurality of first subcarriers that is not set to the null subcarrier, and modulating the second digital signal to the plurality of second subcarriers.
  • the frequency of each of the plurality of first subcarriers and the frequency of each of the plurality of second subcarriers are respectively equal to each other;
  • the preset number of the null subcarriers is less than or equal to half of the total number of the plurality of first subcarriers
  • the null subcarrier Before the phase conjugate value is modulated to the null subcarrier, the null subcarrier does not carry a modulated signal, or the modulated signal carried by the null subcarrier is redundant data;
  • the phase conjugate value carried by the null subcarrier is calculated by calculating a modulated signal carried by a second subcarrier at a frequency at which the null subcarrier is located. of.
  • the second modulation device 1003 specifically includes: a time domain signal converter 1013, a digital to analog converter 1023, a quadrature modulator 1033, a polarization combiner 1043;
  • the time domain signal converter 1013 is configured to convert a modulated signal carried by each target first subcarrier of the plurality of target first subcarriers into a first serial time domain signal, and the plurality of The modulated signal carried by each second subcarrier in the two subcarriers is converted into a second serial time domain signal;
  • the digital-to-analog converter 1023 is configured to convert the first serial time domain signal into a first analog electrical signal, and convert the second serial time domain signal into a second analog electrical signal;
  • the quadrature modulator 1033 is configured to modulate the first analog electrical signal and the second analog electrical signal onto a same optical carrier to obtain a first optical signal and a second optical signal;
  • the polarization combiner 1043 is configured to perform polarization multiplexing on the first optical signal and the second optical signal, and carry an optical carrier carrying the polarization-multiplexed first optical signal and the second optical signal Launch to light Receiver.
  • the time domain signal converter 1013 is configured to perform fast fast on each of the target first subcarriers and the second subcarriers of the plurality of second subcarriers, respectively. Inverse transform and parallel-to-serial conversion, and convert the modulated signal carried by the first subcarrier of each target into a first serial time domain signal, and convert the modulated signal carried by each second subcarrier into a second serial Time domain signal; or,
  • the time domain signal converter 1013 is configured to separately perform upsampling subcarriers on each of the target first subcarriers and the second subcarriers of the plurality of second subcarriers. Modulating and time domain addition, converting the modulated signal carried by the first subcarrier of each target into a first serial time domain signal, and converting the modulated signal carried by each second subcarrier into a second serial time domain signal.
  • the embodiment of the present invention sets a preset number of empty subcarriers in the plurality of first subcarriers, so that the first digital signal is not modulated on the set null subcarrier, and then calculates the frequency of the null subcarrier.
  • the phase conjugate value of the modulated signal carried by the two subcarriers, and the phase conjugate value is modulated onto the corresponding null subcarrier, so that the null subcarrier added with the phase conjugate value and the second subcarrier corresponding to the position form a phase
  • the yoke pair enables the optical receiver to calculate the nonlinear phase noise according to the phase conjugate pair in the optical carrier for phase compensation.
  • the signals in the Y polarization direction are conjugates of the X direction signals, so the actual transmission capacity can be increased to reduce the overhead.
  • FIG. 7 is a schematic structural diagram of another optical transmitter according to an embodiment of the present invention.
  • the optical transmitter includes a serial-to-parallel conversion circuit, an orthogonal mapping circuit, a storage circuit, a phase conjugate circuit, and an IFFT circuit.
  • the serial-to-parallel conversion circuit is configured to transform two original digital signals into two corresponding parallel frequency domain data, and transmit two parallel frequency domain data to the orthogonal mapping circuit;
  • the orthogonal mapping circuit is configured to perform QAM mapping on two parallel frequency domain data, and map the binary bit stream to a complex plane to become a modulated signal, and then perform modulation corresponding to one of the parallel frequency domain data.
  • the signal is mapped to the first group of subcarriers, and the modulated signal corresponding to the other parallel frequency domain data Mapping to the second group of subcarriers, and transmitting the first group of subcarriers and the second group of subcarriers to the storage circuit;
  • a plurality of null subcarriers need to be set, the set null subcarriers are reserved null subcarriers, and modulation signal modulation is not allowed to be mapped thereto, and the null subcarriers are set.
  • the total number of subcarriers is less than or equal to half of the total number of subcarriers of the first group, and the number of null subcarriers is not less than one, and the number of subcarriers of the first group is the same as the number of subcarriers of the second group;
  • the frequency of each subcarrier in the group subcarrier is equal to the frequency of each subcarrier in the second group of subcarriers.
  • the storage circuit is configured to store a first group of subcarriers and a second group of subcarriers.
  • the phase conjugate circuit is configured to extract, from the first group of subcarriers and/or the second group of subcarriers stored by the storage circuit, a null subcarrier, and another group of subcarriers at a frequency at which the null subcarrier is located, and then Calculating a phase conjugate value of a modulated signal carried by another group of subcarriers at a frequency at which the null subcarrier is located, and modulating the phase conjugate value onto the corresponding null subcarrier, and carrying the null subcarrier in the storage circuit
  • the modulated signal is updated to a corresponding phase conjugate value such that the modulated signal carried by the null subcarrier can form a phase conjugate pair with the modulated signal carried by another set of subcarriers at the same frequency position.
  • the storage circuit may use the first group of subcarriers as the target first group of subcarriers, and The two sets of subcarriers serve as the target second group of subcarriers, that is, the modulated signals carried by the target first group of subcarriers and the subcarriers of the second group of subcarriers set to be null subcarriers become corresponding phase conjugate values.
  • the IFFT circuit is configured to perform an inverse fast Fourier transform on the target first group of subcarriers and the target second group of subcarriers.
  • the parallel-serial conversion circuit is configured to perform parallel-to-serial conversion on the first group of subcarriers and the second group of subcarriers after the inverse fast Fourier transform to obtain the first serial time domain signal and the second Serial time domain signal.
  • the CP insertion circuit is configured to insert a CP into the first serial time domain signal and the second serial time domain signal, respectively.
  • the DAC circuit is configured to convert the first serial time domain signal after the CP is inserted into the first simulation
  • the electrical signal converts the second serial time domain signal inserted into the CP into a second analog electrical signal.
  • the driver is configured to transmit the first analog electrical signal and the second analog electrical signal to the quadrature modulator.
  • the laser is configured to provide a light source that is converted into two identical optical carriers by an optical splitter, and two identical optical carriers are respectively transmitted to the orthogonal modulator.
  • a quadrature modulator for modulating a first analog electrical signal onto one of the optical carriers, and modulating the second analog electrical signal to another optical carrier, and transmitting the two optical carriers carrying the analog electrical signal to On the PBC.
  • the PBC is configured to perform polarization multiplexing on two optical carriers carrying analog electrical signals to form a polarization multiplexed signal.
  • the embodiment of the present invention sets a preset number of null subcarriers in the first group of subcarriers and/or the second group of subcarriers, so that the original digital signal is not modulated on the set null subcarrier, and then is calculated by The phase conjugate value of the modulated signal carried by the other group of subcarriers at the frequency of the null subcarrier, and the phase conjugate value is modulated onto the corresponding null subcarrier, so that the null subcarrier to which the phase conjugate value is added and the corresponding position can be Another group of subcarriers forms a phase conjugate pair, so that the optical receiver can calculate nonlinear phase noise according to the phase conjugate pair in the optical carrier for phase compensation, since only the null subcarrier and another group of subcarriers at the corresponding location are needed.
  • the phase conjugate pair it is not necessary to require the signal of the entire Y polarization direction to be the conjugate of the X direction signal, so that the actual transmission
  • FIG. 8 is a schematic structural diagram of still another optical transmitter according to an embodiment of the present invention.
  • the optical transmitter may include a serial-to-parallel conversion circuit, an orthogonal mapping circuit, a storage circuit, a phase conjugate circuit, and an upsampling.
  • the serial-to-parallel conversion circuit For the specific implementation of the serial-to-parallel conversion circuit, the orthogonal mapping circuit, the storage circuit, the phase conjugate circuit, the DAC circuit, the driver, the laser, the orthogonal modulator, and the PBC in FIG. 8 , refer to the corresponding embodiment in FIG. 7 above.
  • the serial-to-parallel conversion circuit, the orthogonal mapping circuit, the storage circuit, the phase conjugate circuit, the DAC circuit, the driver, the laser, the quadrature modulator, and the PBC are not described herein.
  • the upsampled subcarrier modulation circuit is configured to perform upsampling subcarrier modulation on a target first group of subcarriers and a target second group of subcarriers transmitted by the storage circuit, respectively, to obtain a first parallel time domain signal and a first Two parallel time domain signals.
  • the time domain adding circuit is configured to perform time domain addition on the first parallel time domain signal and the second parallel time domain signal, respectively, to obtain the first serial time domain signal and the second serial time domain signal, respectively. And transmitting the first serial time domain signal and the second serial time domain signal to the DAC circuit, so that the DAC circuit converts the first serial time domain signal into the first analog electrical signal, and the second serial time domain The signal is converted to a second analog electrical signal.
  • the embodiment of the present invention sets a preset number of null subcarriers in the first group of subcarriers and/or the second group of subcarriers, so that the original digital signal is not modulated on the set null subcarrier, and then is calculated by The phase conjugate value of the modulated signal carried by the other group of subcarriers at the frequency of the null subcarrier, and the phase conjugate value is modulated onto the corresponding null subcarrier, so that the null subcarrier to which the phase conjugate value is added and the corresponding position can be Another group of subcarriers forms a phase conjugate pair, so that the optical receiver can calculate nonlinear phase noise according to the phase conjugate pair in the optical carrier for phase compensation, since only the null subcarrier and another group of subcarriers at the corresponding location are needed.
  • the phase conjugate pair it is not necessary to require the signal of the entire Y polarization direction to be the conjugate of the X direction signal, so that the actual transmission
  • the storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

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Abstract

本发明实施例公开一种非线性补偿的调制方法、装置以及光发射机，其中所述方法包括：在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上；其中，所述第一数字信号不调制到所述空子载波上；计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目标第一子载波；将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机。采用本发明，可提高光通信时的传输容量，并减小开销。

Description

一种非线性补偿的调制方法、装置以及光发射机 技术领域
本发明涉及通信技术领域，尤其涉及一种非线性补偿的调制方法、装置以及光发射机。
背景技术
在光通信中，理论上可以通过提高发射端的光功率，使得在通过光纤链路传输后，得到足够高的光信噪比，使得信号可以达到足够低的误码率，达到传输的需求。但是由于光纤本身的非线性效应，过高的入纤功率会带来非线性噪声，从而使得信号劣化，入纤功率不能无限提高。在传统光相位共轭系统中，一般在光纤链路的中间节点，通过泵浦激光源和高非线性光纤，在其他光频谱上产生原光信号的相位共轭信号，并且具有共轭的相位特性，光纤链路具备对称性的条件下，相位共轭信号在传完后半段链路时，其非线性相位噪声将被抵消。这种在其他光频谱上产生相位共轭光信号的方法，占用了频谱资源，使得系统的频谱利用率下降，而且要引入额外的泵浦激光器以及高非线性光纤，而且对链路的对称性有要求，因此缺乏商用化的可能性。
在现有技术中，存在一种相位共轭的XY双偏振传输系统，该系统中传输的数据以及其复共轭数据分别调制到正交的两个偏振上面，在接收端，通过信号处理技术进行载波恢复之后，将其中Y偏振的数据取共轭，然后与X偏振的数据相加，来减少非线性相位噪声。该系统虽然可以摆脱对泵浦激光源，高非线性光纤等硬件的需求，但由于Y偏振方向的信号为X方向信号的共轭，因此实际传输的容量降低了一半，导致开销的增大。
发明内容
本发明实施例提供一种非线性补偿的调制方法、装置以及光发射机，可提高光通信时的传输容量，并减小开销。
本发明第一方面提供了一种非线性补偿的调制方法，包括：
在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上；其中，所述第一数字信号不调制到所述空子载波上；
计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目标第一子载波；
将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿。
在第一种可能的实现方式中，所述在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上，包括：
在多个第一子载波中选择预设数量的第一子载波，并将选择出的预设数量的第一子载波设置为空子载波；
将第一数字信号调制到所述多个第一子载波中未被设置为所述空子载波的第一子载波上，将第二数字信号调制到多个第二子载波上。
结合第一方面，或第一方面的第一种可能的实现方式，在第二种可能的实现方式中，所述多个第一子载波中各第一子载波所在频率与所述多个第二子载波中各第二子载波所在频率分别对应相等；
所述空子载波的预设数量小于或等于所述多个第一子载波的总数的一半；
在所述相位共轭值调制到所述空子载波之前，所述空子载波不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据；
在所述相位共轭值调制到所述空子载波之后，所述空子载波携带的所述相位共轭值是通过对处于所述空子载波所在频率的第二子载波所携带的调制信号进行计算得到的。
结合第一方面，或第一方面的第一种可能的实现方式，或第一方面的第二 种可能的实现方式，在第三种可能的实现方式中，所述将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机，包括：
将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第二子载波所携带的调制信号转换为第二串行时域信号；
将所述第一串行时域信号转换为第一模拟电信号，并将所述第二串行时域信号转换为第二模拟电信号；
将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，并对所述第一光信号和所述第二光信号进行偏振复用；
将携带有偏振复用后的第一光信号和第二光信号的光载波发射到光接收机。
结合第一方面的第三种可能的实现方式，在第四种可能的实现方式中，所述将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第二子载波所携带的调制信号转换为第二串行时域信号，具体包括：
分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号；或者，
分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号。
本发明第二方面提供了一种非线性补偿的调制装置，包括：
第一调制模块，用于在多个第一子载波中设置预设数量的空子载波，并将 第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上；其中，所述第一数字信号不调制到所述空子载波上；
计算模块，用于计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并通知所述第一调制模块将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目标第一子载波；
第二调制模块，用于将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿。
在第一种可能的实现方式中，所述第一调制模块包括：
设置单元，用于在多个第一子载波中选择预设数量的第一子载波，并将选择出的预设数量的第一子载波设置为空子载波；
调制单元，用于将第一数字信号调制到所述多个第一子载波中未被设置为所述空子载波的第一子载波上，将第二数字信号调制到多个第二子载波上。
结合第二方面，或第二方面的第一种可能的实现方式，在第二种可能的实现方式中，
所述多个第一子载波中各第一子载波所在频率与所述多个第二子载波中各第二子载波所在频率分别对应相等；
所述空子载波的预设数量小于或等于所述多个第一子载波的总数的一半；
在所述相位共轭值调制到所述空子载波之前，所述空子载波不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据；
在所述相位共轭值调制到所述空子载波之后，所述空子载波携带的所述相位共轭值是通过对处于所述空子载波所在频率的第二子载波所携带的调制信号进行计算得到的。
结合第二方面，或第二方面的第一种可能的实现方式，或第二方面的第二种可能的实现方式，在第三种可能的实现方式中，所述第二调制模块包括：
时域信号转换单元，用于将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第 二子载波所携带的调制信号转换为第二串行时域信号；
电信号转换单元，用于将所述第一串行时域信号转换为第一模拟电信号，并将所述第二串行时域信号转换为第二模拟电信号；
光信号调制单元，用于将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，并对所述第一光信号和所述第二光信号进行偏振复用；
发射单元，用于将携带有偏振复用后的第一光信号和第二光信号的光载波发射到光接收机。
结合第二方面的第三种可能的实现方式，在第四种可能的实现方式中，
所述时域信号转换单元，具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号；或者，
所述时域信号转换单元，具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号。
本发明第三方面提供了一种光发射机，包括：第一调制装置、处理器、第二调制装置；
所述第一调制装置，用于在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上；其中，所述第一数字信号不调制到所述空子载波上；
所述处理器，用于计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并通知所述第一调制装置将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目标第一子载波；
所述第二调制装置，用于将所述多个目标第一子载波与所述多个第二子载 波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿。
在第一种可能的实现方式中，所述第一调制装置，具体用于在多个第一子载波中选择预设数量的第一子载波，并将选择出的预设数量的第一子载波设置为空子载波，并将第一数字信号调制到所述多个第一子载波中未被设置为所述空子载波的第一子载波上，将第二数字信号调制到多个第二子载波上。
结合第三方面，或第三方面的第一种可能的实现方式，在第二种可能的实现方式中，
所述多个第一子载波中各第一子载波所在频率与所述多个第二子载波中各第二子载波所在频率分别对应相等；
所述空子载波的预设数量小于或等于所述多个第一子载波的总数的一半；
在所述相位共轭值调制到所述空子载波之前，所述空子载波不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据；
在所述相位共轭值调制到所述空子载波之后，所述空子载波携带的所述相位共轭值是通过对处于所述空子载波所在频率的第二子载波所携带的调制信号进行计算得到的。
结合第三方面，或第三方面的第一种可能的实现方式，或第三方面的第二种可能的实现方式，在第三种可能的实现方式中，所述第二调制装置具体包括：时域信号转换器、数模转换器、正交调制器、偏振合波器；
所述时域信号转换器，用于将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第二子载波所携带的调制信号转换为第二串行时域信号；
所述数模转换器，用于将所述第一串行时域信号转换为第一模拟电信号，并将所述第二串行时域信号转换为第二模拟电信号；
所述正交调制器，用于将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号；
所述偏振合波器，用于对所述第一光信号和所述第二光信号进行偏振复 用，并将携带有偏振复用后的第一光信号和第二光信号的光载波发射到光接收机。
结合第三方面的第三种可能的实现方式，在第四种可能的实现方式中，
所述时域信号转换器，具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号；或者，
所述时域信号转换器，具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号。
由上可见，本发明实施例通过在多个第一子载波中设置预设数量的空子载波，使得第一数字信号不调制到所设置的空子载波上，再通过计算处于空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将相位共轭值调制到对应的空子载波上，可以使添加有相位共轭值的空子载波与对应位置的第二子载波形成相位共轭对，使光接收机可以根据光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿，由于只需要空子载波与对应位置的第二子载波构成相位共轭对，无需要求整个Y偏振方向的信号均为X方向信号的共轭，所以可以提高实际传输的容量，以降低开销。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本发明实施例提供的一种非线性补偿的调制方法的流程示意图；
图1a是本发明实施例提供的一种子载波的结构示意图；
图2是本发明实施例提供的另一种非线性补偿的调制方法的流程示意图；
图3是本发明实施例提供的一种非线性补偿的调制装置的结构示意图；
图4是本发明实施例提供的一种第一调制模块的结构示意图；
图5是本发明实施例提供的一种第二调制模块的结构示意图；
图6是本发明实施例提供的一种光发射机的结构示意图；
图7是本发明实施例提供的另一种光发射机的结构示意图；
图8是本发明实施例提供的又一种光发射机的结构示意图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
请参见图1，是本发明实施例提供的一种非线性补偿的调制方法的流程示意图，所述方法可以包括：
S101，在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上；其中，所述第一数字信号不调制到所述空子载波上；
具体的，当第一数字信号和第二数字信号输入到光发射机时，所述光发射机先在多个第一子载波中设置预设数量的空子载波，所设置的空子载波是预留出来的空子载波且不允许第一数字信号调制映射到其中，即在后续进行子载波映射时所述第一数字信号不会调制到所设置的空子载波上，其中，所设置的空子载波的数量小于或等于所述多个第一子载波的总数的一半，并且所设置的空子载波的数量也不能少于一个。在设置好一定数量的空子载波后，即可将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上，其中，所述第一数字信号不调制到所述所设置的空子载波上。其中，可并将所述多个第一子载波作为第一组子载波，将所述多个第二子载波作为第二 组子载波。在完成子载波映射之后，所述空子载波依然不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据。在将所述第一数字信号和所述第二数字信号调制到对应的子载波之前，所述光发射机先分别对所述第一数字信号和所述第二数字信号进行串并交换，并将所述第一数字信号和所述第二数字信号均变成并行频域数据，然后再对已变成并行频域数据的第一数字信号和第二数字信号进行QAM(正交幅度调制，Quadrature Amplitude Modulation)映射，并将二进制的比特流映射到复平面上，变成一个个调制符号，下一步即可将所述调制符号映射到相应的子载波上，即将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上。
S102，计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目标第一子载波；
具体的，在将所述第一数字信号和所述第二数字信号调制映射到对应的子载波之后，所述光发射机可以存储所有子载波，再从所存储的各个子载波中提取所设置的空子载波以及所述空子载波所在频率的第二子载波。其中，所述多个第一子载波中各第一子载波所在频率与所述多个第二子载波中各第二子载波所在频率分别对应相等，例如，若存在3个第一子载波和3个第二子载波，那么在第一个位置的第一子载波和第二子载波分别所处的频率相同，在第二个位置的第一子载波和第二子载波分别所处的频率相同，在第三个位置的第一子载波和第二子载波分别所处的频率相同。其中，当所述多个第一子载波和所述多个第二子载波分别通过相同长度的IFFT(快速傅立叶逆变换，inverse fast Fourier transform)变换所得到时，就可以保证处于相同位置的第一子载波和第二子载波具有相同的频率。
在提取出所设置的空子载波以及所述空子载波所在频率的第二子载波之后，所述光发射机可以计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将所述相位共轭值调制到对应频率的所述空子载波上。例如，某个空子载波为X1，该空子载波所在频率的第二子载波为Y1，第 二子载波Y1所携带的调制信号为y，若y＝a+jb，则可以计算y的相位共轭值z＝a-jb，再将所计算出的相位共轭值调制到空子载波X1中，使空子载波所携带的调制信号变为z＝a-jb，此时，第一子载波X1所携带的调制信号z与第二子载波Y1所携带的调制信号y形成相位共轭对。由此可见，在所述相位共轭值调制到所述空子载波之前，所述空子载波不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据；在所述相位共轭值调制到所述空子载波之后，所述空子载波携带的所述相位共轭值是通过对处于所述空子载波所在频率的第二子载波所携带的调制信号进行计算得到的。在将所述相位共轭值调制到对应频率的所述空子载波上之后，并将所述多个第一子载波作为多个目标第一子载波，即所述多个目标第一子载波中被设置为空子载波的第一子载波所携带的调制信号均变为对应的相位共轭值。
S103，将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿；
具体的，在将所述多个第一子载波作为多个目标第一子载波之后，可以分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号，再分别向所述第一串行时域信号和所述第二串行时域信号插入CP(循环前缀，Cyclic Prefix)，再将插入CP后的第一串行时域信号转换成第一模拟电信号，将插入CP后的第二串行时域信号转换成第二模拟电信号；最后再将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，并对所述第一光信号和所述第二光信号进行偏振复用，使得所述第一光信号和所述第二光信号可以分别处于不同的偏振态上。
或者，在将所述多个第一子载波作为多个目标第一子载波之后，可以分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各 第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号，再将所述第一串行时域信号转换成第一模拟电信号，将所述第二串行时域信号转换成第二模拟电信号；最后再将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，并对所述第一光信号和所述第二光信号进行偏振复用，使得所述第一光信号和所述第二光信号可以分别处于不同的偏振态上。
再请参见图1a，是本发明实施例提供的一种子载波的结构示意图，如图1a所示，第一数字信号为Y，第二数字信号为X，X1至X9为多个第二子载波中的9个子载波，Y1至Y9为多个第一子载波中的9个子载波，其中，Y2、Y5、Y8为预先设置好的三个空子载波；当X和Y输入到光发射机时，所述光发射机可并将部分X分别调制映射到多个第二子载波中的X1至X9，并同时将部分Y分别调制映射到多个第一子载波中的Y1、Y3、Y4、Y6、Y7、Y9，其中，第一数字信号不会调制映射到空子载波Y2、Y5以及Y8，且同一列的第一子载波和第二子载波所处的频率相同；所述光发射机再选择出所述空子载波所在频率的第二子载波，即提取出X2、X5、X8，再分别计算X2、X5、X8所携带的调制信号的相位共轭值，并将所计算出的相位共轭值调制到对应的空子载波上，即将X2的相位共轭值调制到Y2上、将X5的相位共轭值调制到Y5上、将X8的相位共轭值调制到Y8上，并将Y1到Y9的第一子载波作为目标第一子载波，即所述目标第一子载波中的Y2、Y5、Y8中的调制信号均变为对应的第二子载波所携带的调制信号的相位共轭值。所述光发射机再分别将所述目标第一子载波和所述第二子载波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿。在所述光接收机侧，所述光接收机通过相干接收光前端，光信号变成电信号，经ADC(模/数转换器，Analog-to-Digital Converter)采样变成数字信号，然后经过时钟恢复，色散补偿以及载波恢复后，还原得到带有相位噪声的频分复用信号，例如X2和Y2子频，由于它们同频，同幅度， 因此非线性噪声项具有高相关性，非线性项展开成级数后取一级近似，可认为相等，可以写为arg(X2distorted*Y2distorted)/2，其中X2distorted和Y2distorted是通过光接收机计算得到的已知信息，推导过程为arg(X2distorted*Y2distorted)/2＝arg(S(X2)*exp(jθ)*S(Y2)*exp(jβ))/2，由于S(Y2)和S(X2)相位共轭，因此相乘后相位为零，只剩下相位噪声项相乘，因此求相位后除以二即是相位噪声项：arg(exp(jθ)*exp(jβ))/2，然后再根据arg(exp(jθ)*exp(jβ))/2的值将X1，X2，X3，Y1，Y3的相位噪声项消除掉，从而提高信号的质量，即每六个子载波中有一个是冗余的子载波，所以可以使开销降低到20％。
当然本发明实施例对空子载波的设置不仅限于图1a的方式，所述光发射机可以只在多个第一子载波中设置预设数量的空子载波，也可以只在多个第二子载波中设置预设数量的空子载波；或者，也可以在多个第一子载波中设置第一预设数量的空子载波，同时在多个第二子载波中设置第二预设数量的空子载波，其实现过程也是通过空子载波构造相位共轭对，使得光接收机可以根据相位共轭对来计算相位噪声项，以对各个子载波进行相位补偿。其中，只要保证与空子载波所在频率相同的子载波中的调制信号不为零且不为冗余数据，且保证总的空子载波的数量小于或等于多个第一子载波的总数的一半，即可提高信号的质量，并降低开销；其中，多个第一子载波的总数与多个第二子载波的总数相同。
由上可见，本发明实施例通过在多个第一子载波中设置预设数量的空子载波，使得第一数字信号不调制到所设置的空子载波上，再通过计算处于空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将相位共轭值调制到对应的空子载波上，可以使添加有相位共轭值的空子载波与对应位置的第二子载波形成相位共轭对，使光接收机可以根据光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿，由于只需要空子载波与对应位置的第二子载波构成相位共轭对，无需要求整个Y偏振方向的信号均为X方向信号的共轭，所以可以提高实际传输的容量，以降低开销。
请参见图2，是本发明实施例提供的另一种非线性补偿的调制方法的流程 示意图，所述方法可以包括：
S201，在多个第一子载波中选择预设数量的第一子载波，并将选择出的预设数量的第一子载波设置为空子载波；
具体的，当第一数字信号和第二数字信号输入到光发射机时，所述光发射机先在多个第一子载波中设置预设数量的空子载波，所设置的空子载波是预留出来的空子载波且不允许第一数字信号调制映射到其中，即在后续进行子载波映射时所述第一数字信号不会调制到所设置的空子载波上，其中，所设置的空子载波的数量小于或等于所述多个第一子载波的总数的一半，并且所设置的空子载波的数量也不能少于一个。
S202，将第一数字信号调制到所述多个第一子载波中未被设置为所述空子载波的第一子载波上，将第二数字信号调制到多个第二子载波上；
具体的，在设置好一定数量的空子载波后，即可将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上，其中，所述第一数字信号不调制到所述所设置的空子载波上。在完成子载波映射之后，所述空子载波依然不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据。在将所述第一数字信号和所述第二数字信号调制到对应的子载波之前，所述光发射机先分别对所述第一数字信号和所述第二数字信号进行串并交换，并将所述第一数字信号和所述第二数字信号均变成并行频域数据，然后再对已变成并行频域数据的第一数字信号和第二数字信号进行QAM映射，并将二进制的比特流映射到复平面上，变成一个个调制符号，下一步即可将所述调制符号映射到相应的子载波上，即将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上。
S203，计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目标第一子载波；
具体的，在将所述第一数字信号和所述第二数字信号调制映射到对应的子载波之后，所述光发射机可以存储所有子载波，再从所存储的各个子载波中提 取所设置的空子载波以及所述空子载波所在频率的第二子载波。其中，所述多个第一子载波中各第一子载波所在频率与所述多个第二子载波中各第二子载波所在频率分别对应相等，例如，若存在3个第一子载波和3个第二子载波，那么在第一个位置的第一子载波和第二子载波分别所处的频率相同，在第二个位置的第一子载波和第二子载波分别所处的频率相同，在第三个位置的第一子载波和第二子载波分别所处的频率相同。其中，当所述多个第一子载波和所述多个第二子载波分别通过相同长度的IFFT变换所得到时，就可以保证处于相同位置的第一子载波和第二子载波具有相同的频率。
在提取出所设置的空子载波以及所述空子载波所在频率的第二子载波之后，所述光发射机可以计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将所述相位共轭值调制到对应频率的所述空子载波上。例如，某个空子载波为X1，该空子载波所在频率的第二子载波为Y1，若Y1＝a+jb，则可以计算Y1的相位共轭值z1＝a-jb，再将所计算出的相位共轭值调制到空子载波X1中，使X1＝a-jb，此时，第一子载波X1与第二子载波Y1形成相位共轭对。由此可见，在所述相位共轭值调制到所述空子载波之前，所述空子载波不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据；在所述相位共轭值调制到所述空子载波之后，所述空子载波携带的所述相位共轭值是通过对处于所述空子载波所在频率的第二子载波所携带的调制信号进行计算得到的。在将所述相位共轭值调制到对应频率的所述空子载波上之后，可并将所述多个第一子载波作为多个目标第一子载波，即所述多个目标第一子载波中被设置为空子载波的第一子载波所携带的调制信号均变为对应的相位共轭值。
S204，将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第二子载波所携带的调制信号转换为第二串行时域信号；
具体的，在将所述多个第一子载波作为多个目标第一子载波之后，可以分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中 各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号。
或者，在将所述多个第一子载波作为多个目标第一子载波之后，可以分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号。
S205，将所述第一串行时域信号转换为第一模拟电信号，并将所述第二串行时域信号转换为第二模拟电信号；
具体的，当所述光发射机是通过快速傅里叶逆变换和并串转换得到所述第一串行时域信号和所述第二串行时域信号时，先分别向所述第一串行时域信号和所述第二串行时域信号插入CP，再通过DAC(数/模转换器，Digital-to-Analog Converter)将插入CP后的第一串行时域信号转换为第一模拟电信号，并通过DAC将插入CP后的第二串行时域信号转换为第二模拟电信号。
当所述光发射机是通过上采样子载波调制和时域相加得到所述第一串行时域信号和所述第二串行时域信号时，直接通过DAC将插入CP后的第一串行时域信号转换为第一模拟电信号，并通过DAC将插入CP后的第二串行时域信号转换为第二模拟电信号。
S206，将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，并对所述第一光信号和所述第二光信号进行偏振复用；
具体的，所述光发射机通过驱动器分别将所述第一模拟电信号和所述第二模拟电信号连接到正交调制器上，再通过所述正交调制器将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，再通过偏振合波器对所述第一光信号和所述第二光信号进行偏振复用，使得所述第一光信号和所述第二光信号可以分别处于不同的偏振态上。
S207，将携带有偏振复用后的第一光信号和第二光信号的光载波发射到光 接收机；
具体的，偏振合波器对所述第一光信号和所述第二光信号进行偏振复用后，所述偏振合波器将偏振复用的多载波光信号发射到所述光接收机，所述偏振复用的多载波光信号包括分别处于不同的偏振态上的第一光信号和第二光信号。
在所述光接收机侧，所述光接收机通过相干接收光前端，光信号变成电信号，经ADC采样变成数字信号，然后经过时钟恢复，色散补偿以及载波恢复后，还原得到带有相位噪声的频分复用信号。以上述图1a中的X2和Y2子频为例，由于它们同频，同幅度，因此非线性噪声项具有高相关性，非线性项展开成级数后取一级近似，可认为相等，可以写为arg(X2distorted*Y2distorted)/2，其中X2distorted和Y2distorted是通过光接收机计算得到的已知信息，推导过程为arg(X2distorted*Y2distorted)/2＝arg(S(X2)*exp(jθ)*S(Y2)*exp(jβ))/2，由于S(Y2)和S(X2)相位共轭，因此相乘后相位为零，只剩下相位噪声项相乘，因此求相位后除以二即是相位噪声项：arg(exp(jθ)*exp(jβ))/2，然后再根据arg(exp(jθ)*exp(jβ))/2的值将X1，X2，X3，Y1，Y3的相位噪声项消除掉，从而提高信号的质量，即每六个子载波中有一个是冗余的子载波，所以可以使开销降低到20％。
由上可见，本发明实施例通过在多个第一子载波中设置预设数量的空子载波，使得第一数字信号不调制到所设置的空子载波上，再通过计算处于空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将相位共轭值调制到对应的空子载波上，可以使添加有相位共轭值的空子载波与对应位置的第二子载波形成相位共轭对，使光接收机可以根据光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿，由于只需要空子载波与对应位置的第二子载波构成相位共轭对，无需要求整个Y偏振方向的信号均为X方向信号的共轭，所以可以提高实际传输的容量，以降低开销。
请参见图3，是本发明实施例提供的一种非线性补偿的调制装置的结构示意图，所述非线性补偿的调制装置1可以用于光发射机中，所述非线性补偿的 调制装置1包括：第一调制模块10、计算模块20、第二调制模块30；
所述第一调制模块10，用于在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上；其中，所述第一数字信号不调制到所述空子载波上；
具体的，当第一数字信号和第二数字信号输入到光发射机时，所述第一调制模块10先在多个第一子载波中设置预设数量的空子载波，所设置的空子载波是预留出来的空子载波且不允许第一数字信号调制映射到其中，即在后续进行子载波映射时所述第一数字信号不会调制到所设置的空子载波上，其中，所设置的空子载波的数量小于或等于所述多个第一子载波的总数的一半，并且所设置的空子载波的数量也不能少于一个。在设置好一定数量的空子载波后，即可将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上，其中，所述第一数字信号不调制到所述所设置的空子载波上。其中，可并将所述多个第一子载波作为第一组子载波，将所述多个第二子载波作为第二组子载波。在完成子载波映射之后，所述空子载波依然不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据。所述第一调制模块10在将所述第一数字信号和所述第二数字信号调制到对应的子载波之前，需要先分别对所述第一数字信号和所述第二数字信号进行串并交换，并将所述第一数字信号和所述第二数字信号均变成并行频域数据，然后再对已变成并行频域数据的第一数字信号和第二数字信号进行QAM映射，并将二进制的比特流映射到复平面上，变成一个个调制符号，下一步即可将所述调制符号映射到相应的子载波上，即将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上。
所述计算模块20，用于计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并通知所述第一调制模块10将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目标第一子载波；
具体的，在所述第一调制模块10将所述第一数字信号和所述第二数字信 号调制映射到对应的子载波之后，所述计算模块20可以存储所有子载波，再从所存储的各个子载波中提取所设置的空子载波以及所述空子载波所在频率的第二子载波。其中，所述多个第一子载波中各第一子载波所在频率与所述多个第二子载波中各第二子载波所在频率分别对应相等，例如，若存在3个第一子载波和3个第二子载波，那么在第一个位置的第一子载波和第二子载波分别所处的频率相同，在第二个位置的第一子载波和第二子载波分别所处的频率相同，在第三个位置的第一子载波和第二子载波分别所处的频率相同。其中，当所述多个第一子载波和所述多个第二子载波分别通过相同长度的IFFT变换所得到时，就可以保证处于相同位置的第一子载波和第二子载波具有相同的频率。
在提取出所设置的空子载波以及所述空子载波所在频率的第二子载波之后，所述计算模块20可以计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将所述相位共轭值调制到对应频率的所述空子载波上。例如，某个空子载波为X1，该空子载波所在频率的第二子载波为Y1，第二子载波Y1所携带的调制信号为y，若y＝a+jb，则所述计算模块20可以计算y的相位共轭值z＝a-jb，再将所计算出的相位共轭值调制到空子载波X1中，使空子载波所携带的调制信号变为z＝a-jb，此时，第一子载波X1所携带的调制信号z与第二子载波Y1所携带的调制信号y形成相位共轭对。由此可见，在所述相位共轭值调制到所述空子载波之前，所述空子载波不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据；在所述相位共轭值调制到所述空子载波之后，所述空子载波携带的所述相位共轭值是通过对处于所述空子载波所在频率的第二子载波所携带的调制信号进行计算得到的。在将所述相位共轭值调制到对应频率的所述空子载波上之后，所述计算模块20可并将所述多个第一子载波作为多个目标第一子载波，即所述多个目标第一子载波中被设置为空子载波的第一子载波所携带的调制信号均变为对应的相位共轭值。
所述第二调制模块30，用于将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机 根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿；
具体的，在所述计算模块20将所述多个第一子载波作为多个目标第一子载波之后，所述第二调制模块30可以分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号，再分别向所述第一串行时域信号和所述第二串行时域信号插入CP，再将插入CP后的第一串行时域信号转换成第一模拟电信号，将插入CP后的第二串行时域信号转换成第二模拟电信号；最后所述第二调制模块30再将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，并对所述第一光信号和所述第二光信号进行偏振复用，使得所述第一光信号和所述第二光信号可以分别处于不同的偏振态上。
或者，在所述计算模块20将所述多个第一子载波作为多个目标第一子载波之后，所述第二调制模块30可以分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号，再将所述第一串行时域信号转换成第一模拟电信号，将所述第二串行时域信号转换成第二模拟电信号；最后所述第二调制模块30再将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，并对所述第一光信号和所述第二光信号进行偏振复用，使得所述第一光信号和所述第二光信号可以分别处于不同的偏振态上。
以上述图1a为例，第一数字信号为Y，第二数字信号为X，X1至X9为多个第二子载波中的9个子载波，Y1至Y9为多个第一子载波中的9个子载波，其中，Y2、Y5、Y8为预先设置好的三个空子载波；当X和Y输入到光发射机时，所述第一调制模块10可并将部分X分别调制映射到多个第二子载波中的X1至X9，并同时将部分Y分别调制映射到多个第一子载波中的Y1、 Y3、Y4、Y6、Y7、Y9，其中，第一数字信号不会调制映射到空子载波Y2、Y5以及Y8，且同一列的第一子载波和第二子载波所处的频率相同；所述计算模块20再选择出所述空子载波所在频率的第二子载波，即提取出X2、X5、X8，再分别计算X2、X5、X8所携带的调制信号的相位共轭值，并将所计算出的相位共轭值调制到对应的空子载波上，即将X2的相位共轭值调制到Y2上、将X5的相位共轭值调制到Y5上、将X8的相位共轭值调制到Y8上，并将Y1到Y9的第一子载波作为目标第一子载波，即所述目标第一子载波中的Y2、Y5、Y8中的调制信号均变为对应的第二子载波所携带的调制信号的相位共轭值。所述第二调制模块30再分别将所述目标第一子载波和所述第二子载波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿。在所述光接收机侧，所述光接收机通过相干接收光前端，光信号变成电信号，经ADC采样变成数字信号，然后经过时钟恢复，色散补偿以及载波恢复后，还原得到带有相位噪声的频分复用信号，例如X2和Y2子频，由于它们同频，同幅度，因此非线性噪声项具有高相关性，非线性项展开成级数后取一级近似，可认为相等，可以写为arg(X2distorted*Y2distorted)/2，其中X2distorted和Y2distorted是通过光接收机计算得到的已知信息，推导过程为arg(X2distorted*Y2distorted)/2＝arg(S(X2)*exp(jθ)*S(Y2)*exp(jβ))/2，由于S(Y2)和S(X2)相位共轭，因此相乘后相位为零，只剩下相位噪声项相乘，因此求相位后除以二即是相位噪声项：arg(exp(jθ)*exp(jβ))/2，然后再根据arg(exp(jθ)*exp(jβ))/2的值将X1，X2，X3，Y1，Y3的相位噪声项消除掉，从而提高信号的质量，即每六个子载波中有一个是冗余的子载波，所以可以使开销降低到20％。
进一步的，再请参见图4，是本发明实施例提供的一种第一调制模块10的结构示意图，所述第一调制模块10包括：设置单元101、调制单元102；
所述设置单元101，用于在多个第一子载波中选择预设数量的第一子载波，并将选择出的预设数量的第一子载波设置为空子载波；
具体的，当第一数字信号和第二数字信号输入到光发射机时，先由所述设 置单元101在多个第一子载波中设置预设数量的空子载波，所设置的空子载波是预留出来的空子载波且不允许第一数字信号调制映射到其中，即在后续进行子载波映射时所述第一数字信号不会调制到所设置的空子载波上，其中，所设置的空子载波的数量小于或等于所述多个第一子载波的总数的一半，并且所设置的空子载波的数量也不能少于一个。
所述调制单元102，用于将第一数字信号调制到所述多个第一子载波中未被设置为所述空子载波的第一子载波上，将第二数字信号调制到多个第二子载波上；
具体的，在所述设置单元101设置好一定数量的空子载波后，所述调制单元102可将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上，其中，所述第一数字信号不调制到所述所设置的空子载波上。在完成子载波映射之后，所述空子载波依然不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据。在将所述第一数字信号和所述第二数字信号调制到对应的子载波之前，所述调制单元102先分别对所述第一数字信号和所述第二数字信号进行串并交换，并将所述第一数字信号和所述第二数字信号均变成并行频域数据，然后再对已变成并行频域数据的第一数字信号和第二数字信号进行QAM映射，并将二进制的比特流映射到复平面上，变成一个个调制符号，下一步即可将所述调制符号映射到相应的子载波上，即将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上。
进一步的，再请参见图5，是本发明实施例提供的一种第二调制模块30的结构示意图，所述第二调制模块30包括：时域信号转换单元301、电信号转换单元302、光信号调制单元303、发射单元304；
所述时域信号转换单元301，用于将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第二子载波所携带的调制信号转换为第二串行时域信号；
具体的，所述时域信号转换单元301具体用于分别对所述多个目标第一子 载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号。
或者，所述时域信号转换单元301具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号。
所述电信号转换单元302，用于将所述第一串行时域信号转换为第一模拟电信号，并将所述第二串行时域信号转换为第二模拟电信号；
具体的，当所述时域信号转换单元301是通过快速傅里叶逆变换和并串转换得到所述第一串行时域信号和所述第二串行时域信号时，所述电信号转换单元302先分别向所述第一串行时域信号和所述第二串行时域信号插入CP，再通过DAC将插入CP后的第一串行时域信号转换为第一模拟电信号，并通过DAC将插入CP后的第二串行时域信号转换为第二模拟电信号。
当所述时域信号转换单元301是通过上采样子载波调制和时域相加得到所述第一串行时域信号和所述第二串行时域信号时，所述电信号转换单元302直接通过DAC将插入CP后的第一串行时域信号转换为第一模拟电信号，并通过DAC将插入CP后的第二串行时域信号转换为第二模拟电信号。
所述光信号调制单元303，用于将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，并对所述第一光信号和所述第二光信号进行偏振复用；
具体的，所述光信号调制单元303通过驱动器分别将所述第一模拟电信号和所述第二模拟电信号连接到正交调制器上，再通过所述正交调制器将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，再通过偏振合波器对所述第一光信号和所述第二光信号进行偏振复用，使得所述第一光信号和所述第二光信号可以分别处于不同的偏振态 上。
所述发射单元304，用于将携带有偏振复用后的第一光信号和第二光信号的光载波发射到光接收机；
具体的，偏振合波器对所述第一光信号和所述第二光信号进行偏振复用后，所述发射单元304通过所述偏振合波器将偏振复用的多载波光信号发射到所述光接收机，所述偏振复用的多载波光信号包括分别处于不同的偏振态上的第一光信号和第二光信号。
由上可见，本发明实施例通过在多个第一子载波中设置预设数量的空子载波，使得第一数字信号不调制到所设置的空子载波上，再通过计算处于空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将相位共轭值调制到对应的空子载波上，可以使添加有相位共轭值的空子载波与对应位置的第二子载波形成相位共轭对，使光接收机可以根据光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿，由于只需要空子载波与对应位置的第二子载波构成相位共轭对，无需要求整个Y偏振方向的信号均为X方向信号的共轭，所以可以提高实际传输的容量，以降低开销。
请参见图6，是本发明实施例提供的一种光发射机的结构示意图，所述光发射机1000可以包括第一调制装置1002、处理器1001、第二调制装置1003(所述光发射机1000中的处理器1001的数量可以为一个或多个，图6中以一个处理器1001为例)。本发明的一些实施例中，第一调制装置1002、处理器1001、第二调制装置1003可通过通信总线或其他方式连接，其中，图6以通过通信总线连接为例。
所述第一调制装置1002，用于在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上；其中，所述第一数字信号不调制到所述空子载波上；
所述处理器1001，用于计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并通知所述第一调制装置1002将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目 标第一子载波；
所述第二调制装置1003，用于将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿。
其中，所述第一调制装置1002，具体用于在多个第一子载波中选择预设数量的第一子载波，并将选择出的预设数量的第一子载波设置为空子载波，并将第一数字信号调制到所述多个第一子载波中未被设置为所述空子载波的第一子载波上，将第二数字信号调制到多个第二子载波上。
其中，所述多个第一子载波中各第一子载波所在频率与所述多个第二子载波中各第二子载波所在频率分别对应相等；
所述空子载波的预设数量小于或等于所述多个第一子载波的总数的一半；
在所述相位共轭值调制到所述空子载波之前，所述空子载波不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据；
在所述相位共轭值调制到所述空子载波之后，所述空子载波携带的所述相位共轭值是通过对处于所述空子载波所在频率的第二子载波所携带的调制信号进行计算得到的。
其中，所述第二调制装置1003具体包括：时域信号转换器1013、数模转换器1023、正交调制器1033、偏振合波器1043；
所述时域信号转换器1013，用于将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第二子载波所携带的调制信号转换为第二串行时域信号；
所述数模转换器1023，用于将所述第一串行时域信号转换为第一模拟电信号，并将所述第二串行时域信号转换为第二模拟电信号；
所述正交调制器1033，用于将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号；
所述偏振合波器1043，用于对所述第一光信号和所述第二光信号进行偏振复用，并将携带有偏振复用后的第一光信号和第二光信号的光载波发射到光 接收机。
其中，所述时域信号转换器1013，具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号；或者，
所述时域信号转换器1013，具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号。
由上可见，本发明实施例通过在多个第一子载波中设置预设数量的空子载波，使得第一数字信号不调制到所设置的空子载波上，再通过计算处于空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将相位共轭值调制到对应的空子载波上，可以使添加有相位共轭值的空子载波与对应位置的第二子载波形成相位共轭对，使光接收机可以根据光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿，由于只需要空子载波与对应位置的第二子载波构成相位共轭对，无需要求整个Y偏振方向的信号均为X方向信号的共轭，所以可以提高实际传输的容量，以降低开销。
再请参见图7，是本发明实施例提供的另一种光发射机的结构示意图，所述光发射机包括串并变换电路、正交映射电路、存储电路、相位共轭电路、IFFT电路、并串转换电路、CP插入电路、DAC电路、驱动器、激光器、正交调制器、PBC(polarization beam combiner，偏振合波器)；
所述串并变换电路，用于将两路原始数字信号分别变换成两路对应的并行频域数据，并将两路并行频域数据传输到所述正交映射电路；
所述正交映射电路，用于对两路并行频域数据进行QAM映射，并将二进制的比特流映射到复平面上，变成一个个调制信号，再将其中一路并行频域数据对应的调制信号映射到第一组子载波，另一路并行频域数据对应的调制信号 映射到第二组子载波，再将第一组子载波和第二组子载波传输到所述存储电路；
其中，在第一组子载波和/或第二组子载波中需要设置若干空子载波，所设置的空子载波是预留出来的空子载波且不允许调制信号调制映射到其中，所设置的空子载波的总数小于或等于第一组子载波的总数的一半，并且所设置的空子载波的数量也不能少于一个，第一组子载波的数量和第二组子载波的数量相同；其中，第一组子载波中各子载波所在频率与第二组子载波中各子载波所在频率分别对应相等。
所述存储电路，用于存储第一组子载波和第二组子载波。
所述相位共轭电路，用于从所述存储电路所存储的第一组子载波和/或第二组子载波中提取出空子载波，以及空子载波所在频率的另一组的子载波，再计算空子载波所在频率的另一组的子载波所携带的调制信号的相位共轭值，再将相位共轭值调制到对应的空子载波上，并将所述存储电路中的空子载波所携带的调制信号更新为对应的相位共轭值，使得空子载波所携带的调制信号可以与相同频率位置上的另一组子载波所携带的调制信号形成相位共轭对。
其中，在将所述存储电路中的空子载波所携带的调制信号更新为对应的相位共轭值后，所述存储电路可并将第一组子载波作为目标第一组子载波，并将第二组子载波作为目标第二组子载波，即目标第一组子载波和目标第二组子载波中被设置为空子载波的子载波所携带的调制信号均变为对应的相位共轭值。
所述IFFT电路，用于对目标第一组子载波和目标第二组子载波进行快速傅里叶逆变换。
所述并串转换电路，用于对快速傅里叶逆变换后的目标第一组子载波和目标第二组子载波分别进行并串转换，以分别得到第一串行时域信号和第二串行时域信号。
所述CP插入电路，用于分别向第一串行时域信号和第二串行时域信号插入CP。
所述DAC电路，用于将插入CP后的第一串行时域信号转换为第一模拟 电信号，再将插入CP后的第二串行时域信号转换为第二模拟电信号。
所述驱动器，用于将第一模拟电信号和第二模拟电信号传输到所述正交调制器。
所述激光器，用于提供光源，该光源经过光分路器变成两路相同的光载波，两路相同的光载波分别传输到所述正交调制器上。
正交调制器，用于将第一模拟电信号调制到其中一路光载波上，并将第二模拟电信号调制到另一路光载波上，再将携带有模拟电信号的两路光载波传输到PBC上。
所述PBC，用于对携带有模拟电信号的两路光载波进行偏振复用，以形成偏振复用信号。
由上可见，本发明实施例通过在第一组子载波和/或第二组子载波中设置预设数量的空子载波，使得原始数字信号不调制到所设置的空子载波上，再通过计算处于空子载波所在频率的另一组子载波所携带的调制信号的相位共轭值，并将相位共轭值调制到对应的空子载波上，可以使添加有相位共轭值的空子载波与对应位置的另一组子载波形成相位共轭对，使光接收机可以根据光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿，由于只需要空子载波与对应位置的另一组子载波构成相位共轭对，无需要求整个Y偏振方向的信号均为X方向信号的共轭，所以可以提高实际传输的容量，以降低开销。
再请参见图8，是本发明实施例提供的又一种光发射机的结构示意图，所述光发射机可以包括串并变换电路、正交映射电路、存储电路、相位共轭电路、上采样子载波调制电路、时域相加电路、DAC电路、驱动器、激光器、正交调制器、PBC；
图8中的所述串并变换电路、正交映射电路、存储电路、相位共轭电路、DAC电路、驱动器、激光器、正交调制器以及PBC的具体实现方式可以参见上述图7对应实施例中的串并变换电路、正交映射电路、存储电路、相位共轭电路、DAC电路、驱动器、激光器、正交调制器以及PBC，这里不再进行赘述。
所述上采样子载波调制电路，用于对所述存储电路所传输的目标第一组子载波和目标第二组子载波分别进行上采样子载波调制，以得到第一并行时域信号和第二并行时域信号。
所述时域相加电路，用于分别对第一并行时域信号和第二并行时域信号进行时域相加，以分别得到第一串行时域信号和第二串行时域信号，并将第一串行时域信号和第二串行时域信号传输到DAC电路，以使DAC电路将第一串行时域信号转换为第一模拟电信号，并将第二串行时域信号转换为第二模拟电信号。
由上可见，本发明实施例通过在第一组子载波和/或第二组子载波中设置预设数量的空子载波，使得原始数字信号不调制到所设置的空子载波上，再通过计算处于空子载波所在频率的另一组子载波所携带的调制信号的相位共轭值，并将相位共轭值调制到对应的空子载波上，可以使添加有相位共轭值的空子载波与对应位置的另一组子载波形成相位共轭对，使光接收机可以根据光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿，由于只需要空子载波与对应位置的另一组子载波构成相位共轭对，无需要求整个Y偏振方向的信号均为X方向信号的共轭，所以可以提高实际传输的容量，以降低开销。
本领域普通技术人员可以理解实现上述实施例方法中的全部或部分流程，是可以通过计算机程序来指令相关的硬件来完成，所述的程序可存储于一计算机可读取存储介质中，该程序在执行时，可包括如上述各方法的实施例的流程。其中，所述的存储介质可为磁碟、光盘、只读存储记忆体(Read-Only Memory，ROM)或随机存储记忆体(Random Access Memory，RAM)等。
以上所揭露的仅为本发明较佳实施例而已，当然不能以此来限定本发明之权利范围，因此依本发明权利要求所作的等同变化，仍属本发明所涵盖的范围。

Claims (15)

  1. 一种非线性补偿的调制方法，其特征在于，包括：
    在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上；其中，所述第一数字信号不调制到所述空子载波上；
    计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目标第一子载波；
    将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿。
  2. 如权利要求1所述的方法，其特征在于，所述在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上，包括：
    在多个第一子载波中选择预设数量的第一子载波，并将选择出的预设数量的第一子载波设置为空子载波；
    将第一数字信号调制到所述多个第一子载波中未被设置为所述空子载波的第一子载波上，将第二数字信号调制到多个第二子载波上。
  3. 如权利要求1或2所述的方法，其特征在于，
    所述多个第一子载波中各第一子载波所在频率与所述多个第二子载波中各第二子载波所在频率分别对应相等；
    所述空子载波的预设数量小于或等于所述多个第一子载波的总数的一半；
    在所述相位共轭值调制到所述空子载波之前，所述空子载波不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据；
    在所述相位共轭值调制到所述空子载波之后，所述空子载波携带的所述相位共轭值是通过对处于所述空子载波所在频率的第二子载波所携带的调制信号进行计算得到的。
  4. 如权利要求1至3任一项所述的方法，其特征在于，所述将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机，包括：
    将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第二子载波所携带的调制信号转换为第二串行时域信号；
    将所述第一串行时域信号转换为第一模拟电信号，并将所述第二串行时域信号转换为第二模拟电信号；
    将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，并对所述第一光信号和所述第二光信号进行偏振复用；
    将携带有偏振复用后的第一光信号和第二光信号的光载波发射到光接收机。
  5. 如权利要求4所述的方法，其特征在于，所述将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第二子载波所携带的调制信号转换为第二串行时域信号，具体包括：
    分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号；或者，
    分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子 载波中各第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号。
  6. 一种非线性补偿的调制装置，其特征在于，包括：
    第一调制模块，用于在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上；其中，所述第一数字信号不调制到所述空子载波上；
    计算模块，用于计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并通知所述第一调制模块将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目标第一子载波；
    第二调制模块，用于将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿。
  7. 如权利要求6所述的装置，其特征在于，所述第一调制模块包括：
    设置单元，用于在多个第一子载波中选择预设数量的第一子载波，并将选择出的预设数量的第一子载波设置为空子载波；
    调制单元，用于将第一数字信号调制到所述多个第一子载波中未被设置为所述空子载波的第一子载波上，将第二数字信号调制到多个第二子载波上。
  8. 如权利要求6或7所述的装置，其特征在于，
    所述多个第一子载波中各第一子载波所在频率与所述多个第二子载波中各第二子载波所在频率分别对应相等；
    所述空子载波的预设数量小于或等于所述多个第一子载波的总数的一半；
    在所述相位共轭值调制到所述空子载波之前，所述空子载波不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据；
    在所述相位共轭值调制到所述空子载波之后，所述空子载波携带的所述相位共轭值是通过对处于所述空子载波所在频率的第二子载波所携带的调制信号进行计算得到的。
  9. 如权利要求6至8任一项所述的装置，其特征在于，所述第二调制模块包括：
    时域信号转换单元，用于将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第二子载波所携带的调制信号转换为第二串行时域信号；
    电信号转换单元，用于将所述第一串行时域信号转换为第一模拟电信号，并将所述第二串行时域信号转换为第二模拟电信号；
    光信号调制单元，用于将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号，并对所述第一光信号和所述第二光信号进行偏振复用；
    发射单元，用于将携带有偏振复用后的第一光信号和第二光信号的光载波发射到光接收机。
  10. 如权利要求9所述的装置，其特征在于，
    所述时域信号转换单元，具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号；或者，
    所述时域信号转换单元，具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号。
  11. 一种光发射机，其特征在于，包括：第一调制装置、处理器、第二调制装置；
    所述第一调制装置，用于在多个第一子载波中设置预设数量的空子载波，并将第一数字信号调制到所述多个第一子载波上，将第二数字信号调制到多个第二子载波上；其中，所述第一数字信号不调制到所述空子载波上；
    所述处理器，用于计算处于所述空子载波所在频率的第二子载波所携带的调制信号的相位共轭值，并通知所述第一调制装置将所述相位共轭值调制到对应频率的所述空子载波上，并将所述多个第一子载波作为多个目标第一子载波；
    所述第二调制装置，用于将所述多个目标第一子载波与所述多个第二子载波调制到光载波上，并将所述光载波发射到光接收机，以使所述光接收机根据所述光载波中的相位共轭对计算出非线性相位噪声以进行相位补偿。
  12. 如权利要求11所述的光发射机，其特征在于，所述第一调制装置，具体用于在多个第一子载波中选择预设数量的第一子载波，并将选择出的预设数量的第一子载波设置为空子载波，并将第一数字信号调制到所述多个第一子载波中未被设置为所述空子载波的第一子载波上，将第二数字信号调制到多个第二子载波上。
  13. 如权利要求11或12所述的光发射机，其特征在于，
    所述多个第一子载波中各第一子载波所在频率与所述多个第二子载波中各第二子载波所在频率分别对应相等；
    所述空子载波的预设数量小于或等于所述多个第一子载波的总数的一半；
    在所述相位共轭值调制到所述空子载波之前，所述空子载波不携带调制信号，或者所述空子载波所携带的调制信号为冗余数据；
    在所述相位共轭值调制到所述空子载波之后，所述空子载波携带的所述相位共轭值是通过对处于所述空子载波所在频率的第二子载波所携带的调制信 号进行计算得到的。
  14. 如权利要求11至13任一项所述的光发射机，其特征在于，所述第二调制装置具体包括：时域信号转换器、数模转换器、正交调制器、偏振合波器；
    所述时域信号转换器，用于将所述多个目标第一子载波中各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将所述多个第二子载波中各第二子载波所携带的调制信号转换为第二串行时域信号；
    所述数模转换器，用于将所述第一串行时域信号转换为第一模拟电信号，并将所述第二串行时域信号转换为第二模拟电信号；
    所述正交调制器，用于将所述第一模拟电信号和所述第二模拟电信号调制到相同的光载波上，以得到第一光信号和第二光信号；
    所述偏振合波器，用于对所述第一光信号和所述第二光信号进行偏振复用，并将携带有偏振复用后的第一光信号和第二光信号的光载波发射到光接收机。
  15. 如权利要求14所述的光发射机，其特征在于，
    所述时域信号转换器，具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行快速傅里叶逆变换和并串转换，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号；或者，
    所述时域信号转换器，具体用于分别对所述多个目标第一子载波中各目标第一子载波与所述多个第二子载波中各第二子载波进行上采样子载波调制和时域相加，并将各目标第一子载波所携带的调制信号转换为第一串行时域信号，并将各第二子载波所携带的调制信号转换为第二串行时域信号。
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