WO2017156786A1 - 一种信号处理方法及相关设备 - Google Patents

一种信号处理方法及相关设备 Download PDF

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Publication number
WO2017156786A1
WO2017156786A1 PCT/CN2016/076800 CN2016076800W WO2017156786A1 WO 2017156786 A1 WO2017156786 A1 WO 2017156786A1 CN 2016076800 W CN2016076800 W CN 2016076800W WO 2017156786 A1 WO2017156786 A1 WO 2017156786A1
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WIPO (PCT)
Prior art keywords
signal
compensation
processing
coefficient
ofdm
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PCT/CN2016/076800
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English (en)
French (fr)
Inventor
司小书
张利
石华平
邱勇
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to PCT/CN2016/076800 priority Critical patent/WO2017156786A1/zh
Priority to EP16893951.0A priority patent/EP3404880B1/en
Publication of WO2017156786A1 publication Critical patent/WO2017156786A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/38—Demodulator circuits; Receiver circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/06—Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection
    • H04L25/061—Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset
    • 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
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H04B2001/0408—Circuits with power amplifiers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT

Definitions

  • the embodiments of the present invention relate to the field of communications technologies, and in particular, to a signal processing method and related devices.
  • a power amplifier is an amplifier that produces maximum output power to drive a load (such as a transmitter) at a given distortion rate. Its performance mainly includes linearity and efficiency. Linearity refers to the difference between the actual output power and the ideal output power as a percentage of the maximum output power. The smaller the value, the better the linearity. The efficiency refers to the difference between the output power and the input power. The percentage of total power.
  • Figure 1 shows the characteristics of the power amplifier.
  • the horizontal axis represents the input power (P IN in dB) and the vertical axis represents the output power (P OUT , in dB).
  • the characteristic curve is divided into a linear region, a nonlinear region and a saturated region.
  • P IN increases, P OUT linearly increases in the linear region, and gradually deviates from the linear output value in the nonlinear interval ( This phenomenon is also called nonlinear distortion, and finally stabilizes in the saturation interval.
  • Working point P 1dB 1dB present (i.e., the actual output power deviates from the ideal position of the output power of 1dB) in the nonlinear region.
  • P 1dB to the left the better the linearity of the power amplifier, the lower the efficiency; P 1dB to the right, the higher the efficiency of the power amplifier, but the worse the linearity (the more serious the nonlinear distortion).
  • Hybrid Fiber Coaxial (HFC) network is a hybrid network combining optical fiber and coaxial cable, including three parts: front-end equipment room, optical node and customer end.
  • the optical node and the user end are connected by a coaxial cable.
  • a power amplifier will be set in the transmission line to compensate for the attenuation, but this will increase the power consumption of the HFC network.
  • the embodiment of the invention discloses a signal processing method and related device, which can perform nonlinear distortion compensation on a signal received by a user end under the premise of reducing power consumption of the HFC network, thereby improving signal quality.
  • a first aspect of the embodiments of the present invention discloses a signal processing method, which is applied to an HFC network, where the HFC network includes at least one power amplifier and a CM, and the method includes:
  • the CM receives the distortion signal, wherein the distortion signal includes a nonlinear frequency component generated by the at least one power amplifier amplifying the signal;
  • the CM converts the distorted signal into a digital signal
  • the CM uses the compensation coefficient to nonlinearly compensate the digital signal to obtain a compensation signal.
  • the nonlinear frequency component includes at least one of a third-order intermodulation component and a fifth-order intermodulation component
  • the compensation coefficient may be an initialization coefficient, or may be a coefficient that is continuously trained and updated on the initialization coefficient. It is also possible to train the initialization coefficient to achieve a stable coefficient for the current coefficient update period.
  • the CM can utilize the compensation coefficient and implement nonlinear compensation for the digital signal in combination with the LMS algorithm or the like.
  • the embodiment of the present invention is unified.
  • the final signal is compensated by the user equipment (ie CM), which can improve the network service capability to a certain extent.
  • the method may further include:
  • the CM performs signal recovery processing on the compensation signal to obtain a reference signal; the reference signal obtained by the signal recovery process can compensate for the channel response, so as to be closer to the signal sent by the optical node device;
  • the CM trains the compensation coefficient by using an error signal between the reference signal and the compensation signal to obtain an update coefficient
  • the CM updates the compensation coefficient to the update coefficient to obtain an updated compensation coefficient.
  • the accuracy of the nonlinear compensation processing of the distorted signal can be improved, thereby improving the quality of the signal finally received by the user end.
  • the compensation signal is an OFDM signal
  • the CM performs signal recovery processing on the compensation signal to obtain a reference signal, including:
  • the CM performs signal recovery processing on the OFDM signal to obtain a first signal
  • the CM determines the first signal as a reference signal.
  • the compensation signal includes the OFDM signal and the QAM signal, and then the CM performs signal recovery processing on the compensation signal to obtain a reference signal, including:
  • the CM performs signal recovery processing on the OFDM signal to obtain a first signal, and performs signal recovery processing on the QAM signal to obtain a second signal;
  • the CM combines the signal obtained by combining the first signal and the second signal as a reference signal.
  • the OFDM signal is generally divided into multiple channels during transmission, the OFDM signal is generally composed of OFDM sub-signals carried on multiple OFDM channels, and then the CM performs signal recovery processing on the OFDM signal to obtain the first Signals, including:
  • the CM For the OFDM sub-signal carried on each OFDM channel, the CM performs DDC processing on the OFDM sub-signal, and performs FFT processing on the DDC processed signal to obtain a carrier signal;
  • the CM performs FEQ processing on the carrier signal by using a pilot signal, and performs hard decision processing on the signal obtained by the FEQ process to obtain a frequency domain signal.
  • the pilot signal includes at least one frequency of a signal sent by the optical node device to the CM. Point, the CM receives the pilot signal while receiving the distortion signal;
  • the CM performs IFFT processing on the frequency domain signal, and performs DUC processing on the signal obtained by the IFFT processing to obtain a first sub-signal;
  • the CM synthesizes the first sub-signals processed on the OFDM sub-signals on all OFDM channels to obtain a first signal.
  • the QAM signal can also be transmitted by using a channel during transmission
  • the QAM signal is also composed of QAM sub-signals carried on at least one QAM channel.
  • the CM performs signal recovery processing on the QAM signal to obtain a second signal, including:
  • the CM For the QAM sub-signal carried on each QAM channel, the CM performs DDC processing on the QAM sub-signal to obtain a baseband signal;
  • the CM performs TEQ processing on the baseband signal, and performs hard decision processing on the signal obtained by the TEQ process to obtain a time domain signal;
  • the CM performs DUC processing on the time domain signal to obtain a second sub-signal
  • the CM synthesizes the second sub-signals obtained by processing the QAM sub-signals on all QAM channels to obtain a second signal.
  • the method may further include:
  • the CM obtains a pre-recorded historical error signal, wherein the historical error signal is an error signal between the historical reference signal and the historical compensation signal obtained by nonlinearly compensating the previous set of digital signals in the current compensation coefficient update period;
  • the CM determines whether an error between the error signal and the historical error signal is greater than a preset error
  • the CM updates the compensation coefficient to the update coefficient, thereby obtaining an updated compensation coefficient.
  • the method may further include:
  • the CM determines the compensation coefficient as a stable compensation coefficient, wherein the stable compensation coefficient is used to nonlinearly compensate the digital signal in the current compensation coefficient update period.
  • the second aspect of the embodiment of the present invention discloses a cable modem CM, which is applied to an HFC network, and the HFC network may further include at least one power amplifier, and the CM includes:
  • a receiving module configured to receive a distortion signal, where the distortion signal includes a nonlinear frequency component generated by the at least one power amplifier amplifying the signal.
  • a conversion module configured to convert the distortion signal received by the receiving module to a digital signal.
  • a compensation module for performing nonlinear compensation on the digital signal by using a compensation coefficient to obtain a compensation signal number.
  • the nonlinear frequency component includes at least one of a third-order intermodulation component and a fifth-order intermodulation component
  • the compensation coefficient may be an initialization coefficient, or may be a coefficient that is continuously trained and updated on the initialization coefficient. It is also possible to train the initialization coefficient to achieve a stable coefficient for the current coefficient update period.
  • the compensation module can utilize the compensation coefficient and implement nonlinear compensation for the digital signal in combination with the LMS algorithm.
  • the embodiment of the present invention is unified.
  • the final signal is compensated by the user equipment (ie CM), which can improve the network service capability to a certain extent.
  • the CM may further include:
  • the recovery module is configured to perform signal recovery processing on the compensation signal obtained by nonlinearly compensating the compensation module to obtain a reference signal.
  • the reference signal obtained by the signal recovery processing by the recovery module can compensate the channel response, so as to be closer to the signal sent by the optical node device.
  • the training module is configured to calculate an error signal between the reference signal obtained by the recovery module for performing signal recovery processing and the compensation signal obtained by the compensation module by nonlinear compensation, and use the error signal to train the compensation coefficient to obtain an update coefficient.
  • an update module configured to update the compensation coefficient to an update coefficient obtained by training the training module, to obtain an updated compensation coefficient, wherein the updated compensation coefficient is used to perform nonlinear compensation on the next set of digital signals.
  • the accuracy of the nonlinear compensation processing of the distorted signal can be improved, thereby improving the quality of the signal finally received by the user end.
  • the foregoing recovery module may include an OFDM signal recovery submodule, a QAM signal recovery submodule, and a determining submodule, where:
  • the compensation module When the downlink of the HFC network only transmits OFDM signals, the compensation module performs nonlinear compensation.
  • the compensation signal is OFDM signal, therefore,
  • the OFDM signal recovery submodule is configured to perform signal recovery processing on the OFDM signal to obtain a first signal
  • the determining submodule is configured to determine the first signal as a reference signal.
  • the compensation signal obtained by the compensation module by performing nonlinear compensation includes the OFDM signal and the QAM signal, therefore,
  • the OFDM signal recovery submodule is configured to perform signal recovery processing on the OFDM signal to obtain a first signal
  • the QAM signal recovery sub-module is configured to perform signal recovery processing on the QAM signal to obtain a second signal
  • the determining submodule is configured to determine the signal obtained by combining the first signal and the second signal as a reference signal.
  • the OFDM signal is generally divided into multiple channels during transmission
  • the OFDM signal is generally composed of OFDM sub-signals carried on multiple OFDM channels, and then the OFDM signal recovery sub-module performs signals on the OFDM signal.
  • the specific way to recover the first signal can be:
  • the first sub-signals processed on the OFDM sub-signals on all OFDM channels are synthesized to obtain a first signal.
  • the QAM signal can also be transmitted by using a channel during transmission
  • the QAM signal is also composed of QAM sub-signals carried on at least one QAM channel.
  • the specific manner in which the QAM signal recovery sub-module performs signal recovery processing on the QAM signal to obtain the second signal may be:
  • the second sub-signals processed on the QAM sub-signals on all QAM channels are combined to obtain a second signal.
  • the CM may further include:
  • An acquisition module for acquiring a pre-recorded historical error signal.
  • the historical error signal is an error signal between the historical reference signal and the historical compensation signal obtained by nonlinearly compensating the previous set of digital signals in the current compensation coefficient update period.
  • the determining module is configured to determine whether an error between the error signal obtained by the training module and the historical error signal acquired by the acquiring module is less than a preset error. If the error is less than the preset error, the update module updates the compensation coefficient to the update coefficient to obtain the updated compensation coefficient.
  • the CM may further include:
  • a determining module configured to determine the compensation coefficient as a stable compensation coefficient when the determining module determines that the error is less than or equal to a preset error, wherein the stable compensation coefficient is used to update the digital signal in the current compensation coefficient update period Perform nonlinear compensation.
  • a third aspect of an embodiment of the present invention discloses another cable modem for use in an HFC network.
  • the HFC network may further include an optical node device and at least one power amplifier, the cable modem including a receiver, an analog to digital converter, and a processor.
  • the receiver is configured to receive a distortion signal obtained by amplifying the signal sent by the at least one power amplifier to the cable modem
  • the analog-to-digital converter is configured to convert the distortion signal into a digital signal
  • the processor is mainly It is used for nonlinearly compensating the digital signal by using the compensation coefficient, obtaining a compensation signal, and performing signal recovery processing on the compensation signal to obtain a reference signal, so that the error between the reference signal and the compensation signal can be utilized.
  • the signal trains and updates the compensation factor.
  • FIG. 1 is a characteristic diagram of a power amplifier disclosed in an embodiment of the present invention.
  • FIG. 2 is a schematic structural diagram of an HFC network according to an embodiment of the present invention.
  • FIG. 3a is a schematic flowchart diagram of a signal processing method according to an embodiment of the present invention.
  • FIG. 3b is a schematic diagram of a frequency domain of a distortion signal disclosed in an embodiment of the present invention.
  • FIG. 4 is a schematic flow chart of another signal processing method according to an embodiment of the present invention.
  • FIG. 5 is a schematic flowchart diagram of still another signal processing method according to an embodiment of the present invention.
  • FIG. 6 is a schematic structural diagram of a cable modem according to an embodiment of the present invention.
  • FIG. 7 is a schematic structural diagram of another cable modem disclosed in an embodiment of the present invention.
  • FIG. 8 is a schematic structural diagram of still another cable modem according to an embodiment of the present invention.
  • the embodiment of the invention discloses a signal processing method and related device, which can perform nonlinear distortion compensation on a signal received by a user end under the premise of reducing power consumption of the HFC network, thereby improving signal quality. The details are described below separately.
  • FIG. 2 is a schematic structural diagram of an HFC network according to an embodiment of the present invention.
  • the front end equipment room, the optical node, and the user end are divided into three parts, and the front end equipment room and the optical node are connected by optical fibers.
  • the optical node and the client end are connected by a coaxial cable.
  • the optical node mainly includes a distributor and an optical node device capable of converting an optical signal into an electrical signal function and converting the digital signal into an analog signal function, such as a coaxial media converter (Cable Media Converter, CMC), etc.; CM and user terminals, such as televisions, computers, telephones, etc.
  • a coaxial media converter Cable Media Converter, CMC
  • CM complementary metal-oxide-semiconductor
  • user terminals such as televisions, computers, telephones, etc.
  • the program signals (including various interactive video, data, and voice services) from the cable television station are first converted into optical signals on the optical fiber in the front-end equipment room; after the optical node, the optical node device transmits the optical signals. It is converted into an electrical signal, which is distributed to the user through a coaxial cable after being distributed by the distributor; after the user terminal, the CM modulates and demodulates the electrical signal and finally transmits it to each user terminal.
  • At least one power amplifier is disposed between the optical node device and each CM, and the PA is used to perform power amplification on the signal transmitted in the coaxial cable to compensate the signal transmission process in the coaxial cable. Attenuation in .
  • the network architecture shown in FIG. 2 only gives a partial number of PAs and CMs, but the specific number of the PAs may be determined according to the distance between the optical node device and the CM, which is not limited in the embodiment of the present invention.
  • the existing HFC network is provided with multiple power amplifiers, and the power consumption of each power amplifier makes the power consumption in the HFC network larger. Therefore, the embodiment of the present invention is proposed under the premise of reducing the power consumption of the HFC network, specifically by reducing the power consumption of the power amplifier.
  • FIG. 3a is a schematic flowchart of a signal processing method according to an embodiment of the present invention.
  • the signal processing method may include the following steps:
  • the CM receives the distortion signal.
  • the distortion signal is obtained by amplifying a signal sent by the at least one power amplifier to the CM by the optical node device.
  • the optical node device converts the optical signal received in the optical trunk into an electrical signal, and further, if the optical signal is a digital signal
  • the optical node device also needs to convert the converted electrical signal into an analog signal, and is amplified by a plurality of power amplifiers and sent to each CM; if the optical signal is an analog signal, the optical node device directly directly transmits the module.
  • the signal is amplified by a plurality of power amplifiers and sent to each CM. That is to say, the distortion signal received by the CM is an analog signal.
  • the embodiment of the present invention reduces the power consumption of the power amplifier by reducing the power consumption of the power amplifier based on the original HFC network, the linearity of the power amplifier is reduced, so that the power amplifier is passed through the input power.
  • the signal processed by the amplification is severely distorted. Therefore, in an HFC network, the signal received by the CM is typically a distorted signal. Since the distance between each CM and the optical node device is different, the degree of distortion of the signal received by each CM will also be different.
  • the OFDM signal and the Quadrature Amplitude Modulation (QAM) signal may be mixed in the HFC network.
  • the signal is not limited in the embodiment of the present invention.
  • the signal sent by the optical node device to the CM is amplified by at least one power amplifier to generate intermodulation distortion
  • the distortion signal finally received by the CM may include a nonlinear frequency component.
  • the nonlinear frequency component may include at least one of a third-order intermodulation component and a fifth-order intermodulation component, as shown in FIG. 3b.
  • FIG. 3b is a schematic diagram of a frequency domain of a distortion signal disclosed in an embodiment of the present invention.
  • the signal transmitted in the HFC network is generally a dual-frequency signal, and the output signal obtained by the signal amplified by at least one power amplifier generates cross-talk distortion, that is, the distortion signal increases the nonlinear frequency component with respect to the signal emitted by the optical node device.
  • the wideband signal is a signal transmitted by the optical node device, and the wideband signal falls within the frequency ⁇ 0 -B to ⁇ 0 +B, and after being amplified by at least one power amplifier, three bands are distributed on both sides of the wideband signal frequency.
  • the order intermodulation component that is, falls within the frequency ⁇ 0 -3B to ⁇ 0 +3B
  • the fifth-order intermodulation component that is, falls within the frequency ⁇ 0 -5B to ⁇ 0 +5B.
  • the third-order intermodulation component has the greatest influence on the broadband signal
  • the fifth-order intermodulation component has the second influence.
  • the CM converts the distortion signal into a digital signal.
  • the CM since the signal transmitted in the coaxial cable is an analog signal, the CM needs to perform analog-to-digital conversion (ADC) before nonlinearly compensating the received distortion signal. Process to get a digital signal.
  • ADC analog-to-digital conversion
  • the CM performs nonlinear compensation on the digital signal by using a compensation coefficient to obtain a compensation signal.
  • the compensation coefficient may be an initialization coefficient, or may be a coefficient that is continuously trained and updated on the initialization coefficient, and may also be a stable coefficient for training the initialization coefficient in the current coefficient update period.
  • the example is not limited.
  • the CM uses the compensation coefficient to nonlinearly compensate the digital signal, and the specific manner of obtaining the compensation signal can be implemented by a Least Mean Square (LMS) algorithm, thereby eliminating nonlinear frequency components included in the distorted signal. .
  • LMS Least Mean Square
  • the CM uses the LMS algorithm to perform nonlinear compensation on the digital signal.
  • the following steps may be specifically included:
  • the digital signal is x[n]
  • the length of w is L, which may be 24 or 32, which is not limited in the embodiment of the present invention
  • the CM shifts the data in X[1] backward by one bit to obtain X[2], and then uses the compensation coefficient to nonlinearly compensate X[2];
  • the compensation coefficient may be a compensation coefficient for nonlinearly compensating the previous set of data, or may be a compensation coefficient after training and updating the compensation coefficient for nonlinearly compensating the previous set of data.
  • the cable modem after receiving the distortion signal amplified by the power amplifier, the cable modem converts the distortion signal into a digital signal and nonlinearly compensates it by using the compensation coefficient. While reducing the power consumption of the HFC network, the quality of the signal received by the UE can be improved. Further, since the number of times the signal received by the CM received by the optical node device is different in the amplification process, and the degree of nonlinear distortion of the signal received by the different CMs is different, the embodiment of the present invention is unified. The final signal is compensated by the user equipment (ie CM), which can improve the network service capability to a certain extent.
  • CM user equipment
  • FIG. 4 is a schematic flowchart diagram of another signal processing method according to an embodiment of the present invention. As shown in FIG. 4, the signal processing method may include the following steps:
  • the CM receives the distortion signal.
  • the distortion signal is obtained by amplifying a signal sent by the at least one power amplifier to the CM by the optical node device, and the distortion signal includes a nonlinear frequency component.
  • the CM converts the distortion signal into a digital signal.
  • the CM performs nonlinear compensation on the digital signal by using a compensation coefficient to obtain a compensation signal.
  • the CM performs signal recovery processing on the compensation signal to obtain a reference signal.
  • the signal recovery process is further performed on the compensation signal to compensate the channel response, and the reference signal, the reference signal and the signal sent by the optical node device are obtained. Closer.
  • the OFDM signal can be transmitted in the HFC network, and the OFDM signal and the QAM signal can be simultaneously transmitted, the manner in which the CM performs signal recovery processing is different for different signals.
  • the CM performs signal recovery processing on the compensation signal, and the specific method for obtaining the reference signal may be:
  • the CM performs signal recovery processing on the OFDM signal to obtain a first signal
  • the CM determines the first signal as a reference signal.
  • the CM performs signal recovery processing on the compensation signal, and the specific method for obtaining the reference signal may be :
  • the CM performs signal recovery processing on the OFDM signal to obtain a first signal, and performs signal recovery processing on the QAM signal to obtain a second signal;
  • the CM combines the signal obtained by combining the first signal and the second signal as a reference signal.
  • the main idea of the OFDM technology is to first divide the spectrum of the OFDM signal into several OFDM channels (such as 192 MHz per channel), and then divide each OFDM channel into several orthogonal subcarriers, and simultaneously high-speed data signals. Converting into parallel low-speed sub-data streams, each sub-data stream is carried on each sub-carrier; the OFDM signal here may include an OFDM sub-signal carried on one OFDM channel, and may also include OFDM sub-signals carried on multiple OFDM channels ; therefore, the The specific manner in which the CM performs signal recovery processing on the OFDM signal to obtain the first signal may include the following steps:
  • the CM For the OFDM sub-signal carried on each OFDM channel, the CM performs digital down conversion (DDC) processing on the OFDM sub-signal, and performs fast Fourier transform on the signal obtained by DDC processing (Fast Fourier) Transform, FFT) to obtain a carrier signal;
  • DDC digital down conversion
  • FFT Fast Fourier Transform
  • the CM performs frequency domain equalization (FEQ) processing on the carrier signal by using a pilot signal, and performs hard decision processing on the signal obtained by the FEQ process to obtain a frequency domain signal;
  • FEQ frequency domain equalization
  • the CM performs an Invert Fast Fourier Transform (IFFT) on the frequency domain signal, and performs a digital up-conversion (DUC) process on the signal obtained by the IFFT processing to obtain a first sub-signal;
  • IFFT Invert Fast Fourier Transform
  • DUC digital up-conversion
  • the CM synthesizes the first sub-signals processed on the OFDM sub-signals on all OFDM channels to obtain a first signal.
  • the CM performs DDC processing on the center frequency of the OFDM sub-signal, and the DDC processing mainly includes operations of lower frequency shifting and downsampling rate.
  • the lower frequency shifting refers to moving the useful spectrum of the digital signal sent from the ADC from the intermediate frequency to the baseband; the downsampling rate is to reduce the data after the spectrum shifting from the high-speed sampling rate of the ADC to a suitable sampling rate level. Decimation implementation. Therefore, the baseband time domain signal can be obtained by DDC processing.
  • the CM performs FFT processing on the baseband time domain signal to convert the baseband time domain signal into a frequency domain signal (ie, a carrier signal).
  • the CM also receives a set of pilot signals while receiving the distorted signal. Therefore, after performing FFT processing on the baseband time domain signal, the CM performs FEQ processing on the carrier signal by using the received pilot signal.
  • the pilot signal includes some frequency points in the signal sent by the optical node device to the CM, and may be one or multiple. That is to say, the optical node device sends a set of pilot signals of a part of the frequency points extracted from the signal while transmitting signals to the CM, and the pilot signals also include location information of each frequency point in the signal.
  • the CM can perform FEQ processing on the carrier signal by using an error between the pilot signal and the frequency point of the corresponding position of the carrier signal.
  • the CM then hard-checks the signal obtained by the FEQ process to obtain a frequency domain signal.
  • the principle of hardly judging the signal obtained by FEQ processing is to deviate from the signal.
  • the frequency is corrected.
  • the CM After hard-processing the signal obtained by the FEQ processing, the CM performs IFFT processing on the obtained frequency domain signal, thereby converting the frequency domain signal into a time domain signal. Then, the CM can perform DUC processing on the center frequency of the signal obtained by the IFFT processing, thereby obtaining the first sub-signal of each channel. Similarly, the DUC processing mainly includes the operation of the upsampling rate and the upshifting. Finally, the CM combines the first sub-signals of each sub-channel through the signal recovery process into a first signal to serve as a reference signal corresponding to the compensation signal.
  • the CM performs signal recovery processing on the OFDM signal in the same manner as above.
  • the specific manner of performing signal recovery processing on the QAM signal will be described below.
  • the QAM signal can also be transmitted by channel during transmission, the QAM signal is also composed of QAM sub-signals carried on at least one QAM channel.
  • the specific manner in which the CM performs signal recovery processing on the QAM signal to obtain the second signal may also include the following steps:
  • the CM performs DDC processing on the QAM sub-signal to obtain a baseband signal
  • the CM performs Time-domain Equalization (TEQ) processing on the baseband signal, and performs hard-throttle processing on the signal obtained by the TEQ process to obtain a time domain signal;
  • TEQ Time-domain Equalization
  • the CM performs DUC processing on the time domain signal to obtain a second sub-signal
  • the CM synthesizes a second sub-signal obtained by processing the QAM sub-signal on all QAM channels to obtain a second signal.
  • the CM first performs DDC processing on it, that is, performs lower frequency shifting and downsampling rate processing, and also obtains a baseband time domain signal, and then baseband time domain signal. TEQ processing is performed to compensate for channel response.
  • the CM performs hard decision processing on the signal obtained by the TEQ processing to obtain a time domain signal, and performs DUC processing (upsampling rate and upper frequency shifting) on the time domain signal, thereby obtaining a second sub-signal.
  • the CM synthesizes the second sub-signals obtained by the signal recovery processing of all QAM channels, thereby obtaining the second signal. Then, the signal synthesized by the second signal and the first signal can be used as a reference signal corresponding to the compensation signal.
  • the CM trains the compensation coefficient by using an error signal between the reference signal and the compensation signal to obtain an update coefficient.
  • the CM after the CM obtains the reference signal by performing signal recovery processing on the compensation signal, the error between the reference signal and the compensation signal can be calculated, thereby obtaining an error signal, and then the compensation coefficient is trained by using the error signal. , thus getting a set of update coefficients.
  • the specific manner in which the CM uses the error signal to train the compensation coefficient to obtain the update coefficient may be: assuming that the digital signal is represented by x[n], and each time from the x[n], the data of length L is nonlinearly compensated.
  • the kth group signal is represented by X[k], and the compensation signal z[k] is obtained by nonlinearly compensating X[k] by the compensation coefficient w(k), and the compensation signal z[k] is the pair of x[n]
  • the signal obtained by nonlinearly compensating the kth data is subjected to signal recovery processing for z[k] to obtain a reference signal d[k], and w(k) represents a compensation coefficient for nonlinearly compensating the kth group data, which is L line.
  • Mu is a preset coefficient, which is a fixed value
  • conj(e[k]) represents a conjugate of the error signal e[k].
  • the CM updates the compensation coefficient to the updated coefficient to obtain an updated compensation coefficient.
  • the CM trains the compensation coefficient by using an error signal, and after obtaining the update coefficient, the currently used compensation coefficient may be updated to the update coefficient.
  • the compensation coefficient used is a preset initialization coefficient, which is denoted as w(1), and the CM will compensate the first group of signals after nonlinear compensation.
  • the initialization coefficient is updated and the updated compensation coefficient is recorded as w(2).
  • the CM can use the w(2) to nonlinearly compensate the second group of signals. It can be seen that the CM uses the compensation coefficient w(k) after the k-1th update when nonlinearly compensating the kth group of signals.
  • the CM when the CM performs nonlinear compensation on the kth group of signals, the CM performs nonlinear compensation by using the k-1th updated compensation coefficient, and then obtains through signal recovery processing.
  • the reference signal is used, and the compensation coefficient after the k-1th update is trained by using the error signal between the reference signal and the compensation signal, and the obtained update coefficient can be used as the compensation coefficient for nonlinear compensation processing of the k+1th group signal. .
  • the accuracy of the nonlinear compensation processing of the distorted signal can be improved, thereby improving the quality of the signal finally received by the user end.
  • FIG. 5 is a schematic flowchart diagram of still another signal processing method according to an embodiment of the present invention. As shown in FIG. 5, the signal processing method may include the following steps:
  • the CM receives the distortion signal.
  • the distortion signal is obtained by amplifying a signal sent by the at least one power amplifier to the CM by the optical node device, and the distortion signal includes a nonlinear frequency component.
  • the CM converts the distortion signal into a digital signal.
  • the CM performs nonlinear compensation on the digital signal by using a compensation coefficient to obtain a compensation signal.
  • the CM performs signal recovery processing on the compensation signal to obtain a reference signal.
  • the CM trains the compensation coefficient by using an error signal between the reference signal and the compensation signal to obtain an update coefficient.
  • the error signal is recorded to determine whether the compensation signal obtained by the nonlinear compensation is stable.
  • the CM acquires a pre-recorded historical error signal.
  • the historical error signal is an error signal between the historical reference signal and the historical compensation signal obtained by nonlinearly compensating the previous set of digital signals in the current compensation coefficient update period.
  • the CM periodically updates the compensation coefficients.
  • the compensation coefficient update period may be 10 ms, which is not limited in the embodiment of the present invention.
  • the CM may directly update the compensation coefficient to the update coefficient after obtaining the update coefficient, and After receiving the next set of distortion signals, the updated compensation coefficient is used for nonlinear compensation; if the update coefficient is the updated compensation coefficient obtained by training the compensation coefficient for the kth time in the current compensation coefficient update period, wherein If k is a positive integer greater than or equal to 2, then the CM first obtains a historical error signal between the historical reference signal and the historical compensation signal obtained by the k-1th nonlinear processing of the digital signal.
  • the CM determines whether an error between the error signal and the historical error signal is greater than a preset error. If yes, go to step 508; if no, go to step 509.
  • the CM calculates an error between the error signal and the historical error signal, thereby determining whether the preset is greater than a preset error. Whether the compensation signal after nonlinear compensation is stable.
  • the CM can be regarded as the current compensation coefficient, and the nonlinear compensation of the digital signal is relatively stable, so that the compensation coefficient can be no longer updated in the current compensation coefficient update period; if the previous set of nonlinear compensation The error signal of the obtained compensation signal and the reference signal is larger than the error signal of the compensation signal obtained by the nonlinear compensation of the group and the error signal of the reference signal (that is, the error is greater than the preset error), then the CM will update the current compensation coefficient. For this update factor. In this way, the compensation coefficient is cyclically updated until the resulting error signal is stable.
  • the CM updates the compensation coefficient to the updated coefficient to obtain an updated compensation coefficient.
  • the updated compensation coefficient is used to nonlinearly compensate the next set of digital signals.
  • the CM determines the compensation coefficient as a stable compensation coefficient.
  • the stabilization compensation coefficient is used for nonlinearly compensating all digital signals in the current compensation coefficient update period. That is to say, if the error signal is smaller than the historical error signal, the error between the compensation signal and the reference signal obtained by the CM can be regarded as nonlinear compensation tends to be stable, and in order to improve the nonlinear compensation efficiency of the signal, the CM is The compensation coefficient is no longer updated during the current compensation coefficient update period.
  • the compensation coefficient for performing the nonlinear compensation processing may be a preset initialization coefficient, or may be a stable compensation coefficient obtained in the current compensation coefficient update period, which is not in the embodiment of the present invention. Make a limit.
  • the compensation coefficient may be a preset initialization coefficient q 1 . If the error between the error signal of the compensation signal and the reference signal and the historical error signal obtained by the k-1th nonlinear compensation is small after the k-th nonlinear compensation of the digital signal, the CM can The compensation coefficient q k-1 used is used as the stable compensation coefficient in this period. The CM uses the q k-1 to digitally compensate the digital signal after the analog-to-digital conversion of the distortion signal in this cycle.
  • the CM will update the compensation coefficient again, and the compensation coefficient used for nonlinearly compensating the digital signal after the analog-to-digital conversion of the distortion signal for the first time may be q k -1, may be initializing coefficients of q 1, it is not limited in embodiments of the present invention.
  • the CM periodically updates the compensation coefficient, and in the same period, if the compensation coefficient used is nonlinearly compensated for the digital signal, the compensation signal and the reference signal are obtained. If the error signal is relatively stable, then the CM will not update the compensation coefficient in the current period, so that the compensation coefficient is used to nonlinearly compensate the digital signal in the current period; if the compensation coefficient used is not for the digital signal.
  • the error signal between the compensation signal obtained by linear compensation and the reference signal is unstable, and the CM will continuously update the compensation coefficient until the error signal is stable. Periodically update the compensation coefficient, and no longer update the compensation coefficient when the error signal is stable in the same period, which can improve the accuracy of nonlinear compensation, thereby improving the signal quality received by the user and improving The efficiency of nonlinearly compensating for distorted signals.
  • FIG. 6 is a schematic structural diagram of a cable modem according to an embodiment of the present invention.
  • the CM may include:
  • the receiving module 601 is configured to receive a distortion signal, where the distortion signal is obtained by amplifying a signal sent by the optical node device to the CM by at least one power amplifier in the HFC network, where the distortion signal includes a nonlinear frequency component, and the nonlinearity
  • the frequency component includes at least one of a third-order intermodulation component and a fifth-order intermodulation component.
  • the conversion module 602 is configured to convert the distortion signal received by the receiving module 601 into a digital signal.
  • the compensation module 603 is configured to perform nonlinear compensation on the digital signal by using a compensation coefficient to obtain a compensation signal to eliminate nonlinear frequency components.
  • the compensation coefficient may be an initialization coefficient, or may be a coefficient that is continuously trained and updated on the initialization coefficient, and may also be a stable coefficient for training the initialization coefficient in the current coefficient update period.
  • the example is not limited.
  • the compensation module 603 can utilize the compensation coefficient and implement nonlinear compensation for the digital signal in combination with the LMS algorithm or the like.
  • FIG. 7 is a structure of another cable modem disclosed in an embodiment of the present invention. schematic diagram. Among them, the CM shown in FIG. 7 is optimized based on the CM shown in FIG. 6. As shown in FIG. 7, the CM may further include:
  • the recovery module 604 is configured to perform signal recovery processing on the compensation signal obtained by performing the nonlinear compensation by the compensation module 603 to obtain a reference signal.
  • the reference signal obtained by the signal recovery processing by the recovery module 604 can compensate for the channel response, so as to be closer to the signal sent by the optical node device.
  • the training module 605 is configured to calculate an error signal between the reference signal obtained by the recovery module 604 for performing signal recovery processing and the compensation signal obtained by the compensation module 603 for nonlinear compensation, and use the error signal to train the compensation coefficient to obtain an update coefficient. .
  • the updating module 606 is configured to update the compensation coefficient to the update coefficient trained by the training module 605, thereby obtaining an updated compensation coefficient, wherein the updated compensation coefficient is used for nonlinearly compensating the next set of digital signals. .
  • the compensation module 602 uses the updated compensation coefficient to nonlinearly compensate the next set of digital signals.
  • the accuracy of the nonlinear compensation processing of the distorted signal can be improved, thereby improving the quality of the signal finally received by the user end.
  • the foregoing recovery module 604 may include an OFDM signal recovery submodule 6041, a QAM signal recovery submodule 6042, and a determining submodule 6043, where:
  • the compensation signal obtained by the compensation module 603 for nonlinear compensation is an OFDM signal, therefore,
  • the OFDM signal recovery sub-module 6041 is configured to perform signal recovery processing on the OFDM signal to obtain a first signal.
  • the determining submodule 6043 is configured to determine the first signal as a reference signal.
  • the compensation signal obtained by the compensation module 603 for nonlinear compensation includes the OFDM signal and the QAM signal, therefore,
  • the OFDM signal recovery sub-module 6041 is configured to perform signal recovery processing on the OFDM signal. Obtaining a first signal
  • the QAM signal recovery sub-module 602 is configured to perform signal recovery processing on the QAM signal to obtain a second signal.
  • the determining submodule 6043 is configured to determine the signal obtained by combining the first signal and the second signal as a reference signal.
  • the OFDM signal is generally divided into multiple channels during transmission, the OFDM signal is generally composed of OFDM sub-signals carried on multiple OFDM channels, and then the OFDM signal recovery sub-module 6041 performs signals on the OFDM signal.
  • the specific way to recover the first signal can be:
  • the first sub-signals processed on the OFDM sub-signals on all OFDM channels are synthesized to obtain a first signal.
  • the QAM signal can also be transmitted by using a channel during transmission
  • the QAM signal is also composed of QAM sub-signals carried on at least one QAM channel.
  • the specific manner in which the QAM signal recovery sub-module 6042 performs signal recovery processing on the QAM signal to obtain the second signal may be:
  • the CM may further include:
  • the obtaining module 607 is configured to obtain a pre-recorded historical error signal.
  • the historical error signal is an error signal between the historical reference signal and the historical compensation signal obtained by nonlinearly compensating the previous set of digital signals in the current compensation coefficient update period.
  • the CM periodically updates the compensation coefficients.
  • the compensation coefficient update period may be 10 ms, which is not limited in the embodiment of the present invention.
  • the determining module 608 is configured to determine whether an error between the error signal obtained by the training module 605 and the historical error signal acquired by the acquiring module 607 is less than a preset error. If the error is less than the preset error, the update module 606 updates the compensation coefficient to the update coefficient to obtain the updated compensation coefficient.
  • the CM may further include:
  • the determining module 609 is configured to determine the compensation coefficient as a stable compensation coefficient when the determining module 608 determines that the error is less than or equal to the preset error, where the stable compensation coefficient is used in the current compensation coefficient update period.
  • the digital signal is nonlinearly compensated.
  • the compensation module 602 uses the stable compensation coefficient to perform nonlinear compensation on the digital signal during the current compensation coefficient update period.
  • the cable modem after receiving the distortion signal amplified by the power amplifier, the cable modem converts the distortion signal into a digital signal and nonlinearly compensates it by using the compensation coefficient.
  • This method can improve the quality of the received signal at the user end while reducing the power consumption of the HFC network.
  • the embodiment of the present invention is unified.
  • User-side device ie CM
  • FIG. 8 is a schematic structural diagram of still another cable modem according to an embodiment of the present invention.
  • the CM depicted in FIG. 8 may include a receiver 801, an analog to digital converter 802, at least one processor 803, a transmitter 804, and a communication bus 805, where:
  • the transmitter 804 is configured to send a compensation signal that is nonlinearly compensated by the CM to each user terminal of the user end.
  • the communication bus 805 is configured to implement a communication connection between the receiver 801, the analog-to-digital converter 802, the processor 803, the receiver 904, and the transmitter 804. among them:
  • the receiver 801 is configured to receive a distortion signal, where the distortion signal is obtained by amplifying a signal sent by the optical node device to the CM by at least one power amplifier in the HFC network, where the distortion signal includes a nonlinear frequency component, and the The linear frequency component includes at least one of a third-order intermodulation component and a fifth-order intermodulation component.
  • the analog-to-digital converter 802 is configured to convert the distortion signal received by the receiver 801 into a digital signal.
  • the processor 803 is configured to perform nonlinear compensation on the digital signal by using a compensation coefficient to obtain a compensation signal to eliminate nonlinear frequency components.
  • the compensation coefficient may be an initialization coefficient, or may be a coefficient that is continuously trained and updated on the initialization coefficient, and may also be a stable coefficient for training the initialization coefficient in the current coefficient update period.
  • the example is not limited.
  • the processor 803 can perform nonlinear compensation on the digital signal by using the compensation coefficient and combining the LMS algorithm and the like.
  • the processor 803 is further configured to: after the digital signal is nonlinearly compensated by using the compensation coefficient to obtain a compensation signal, perform the signal recovery processing on the compensation signal to obtain a reference signal, and use the reference signal to The error signal between the compensation signals trains the compensation coefficient to obtain an update coefficient, and updates the compensation coefficient to the update coefficient to obtain an updated compensation coefficient, wherein the updated compensation coefficient is used to perform the next set of digital signals.
  • Nonlinear compensation is further configured to: after the digital signal is nonlinearly compensated by using the compensation coefficient to obtain a compensation signal, perform the signal recovery processing on the compensation signal to obtain a reference signal, and use the reference signal to The error signal between the compensation signals trains the compensation coefficient to obtain an update coefficient, and updates the compensation coefficient to the update coefficient to obtain an updated compensation coefficient, wherein the updated compensation coefficient is used to perform the next set of digital signals.
  • the accuracy of the nonlinear compensation processing of the distorted signal can be improved, thereby improving the quality of the signal finally received by the user end.
  • the compensation signal is an OFDM signal
  • the specific manner in which the processor 803 performs signal recovery processing on the compensation signal to obtain a reference signal may be:
  • the first signal is determined as a reference signal.
  • the compensation signal includes the OFDM signal and the QAM signal
  • the specific manner in which the processor 803 performs signal recovery processing on the compensation signal to obtain a reference signal may be:
  • the signal obtained by combining the first signal and the second signal is determined as a reference signal.
  • the OFDM signal is generally divided into multiple channels during transmission
  • the OFDM signal is generally composed of OFDM sub-signals carried on multiple OFDM channels, and then the processor 803 is used for the OFDM.
  • the specific way for the signal to perform signal recovery processing to obtain the first signal may be:
  • the first sub-signals processed on the OFDM sub-signals on all OFDM channels are synthesized to obtain a first signal.
  • the QAM signal since the QAM signal can also be transmitted by channel during transmission, the QAM signal is also composed of QAM sub-signals carried on at least one QAM channel. Then, the specific manner in which the processor 803 performs signal recovery processing on the QAM signal to obtain the second signal may be:
  • the second sub-signals processed on the QAM sub-signals on all QAM channels are combined to obtain a second signal.
  • the processor 803 is further configured to: after the compensation coefficient is trained by using the error signal between the reference signal and the compensation signal to obtain an update coefficient, obtain a pre-recorded historical error signal, And determining whether the error between the error signal and the historical error signal is greater than a preset error;
  • the historical error signal is an error signal between the historical reference signal and the historical compensation signal obtained by nonlinearly compensating the previous set of digital signals in the current compensation coefficient update period.
  • the CM periodically updates the compensation coefficients.
  • the compensation coefficient update period may be 10 ms, which is not limited in the embodiment of the present invention.
  • the compensation coefficient is updated to the updated coefficient to obtain the updated compensation coefficient.
  • the processor 803 is further configured to determine the compensation coefficient as a stable compensation coefficient when the error is less than or equal to the preset error, where the stable compensation coefficient is used for the current
  • the digital signal in the compensation coefficient update period is nonlinearly compensated.
  • the compensation coefficient is updated periodically, and the compensation coefficient is no longer updated when the error signal is stable in the same period, which can improve the accuracy of the nonlinear compensation, thereby improving the receiving end of the user.
  • the signal quality and the efficiency of nonlinear compensation for distorted signals are provided.
  • the cable modem after receiving the distortion signal amplified by the power amplifier, the cable modem converts the distortion signal into a digital signal and nonlinearly compensates it by using the compensation coefficient. It can improve the quality of the received signal at the user end while reducing the power consumption of the HFC network. Further, since the number of times the signal received by the CM received by the optical node device is different in the amplification process, and the degree of nonlinear distortion of the signal received by the different CMs is different, the embodiment of the present invention is unified. The final signal is compensated by the user equipment (ie CM), which can improve the network service capability to a certain extent.
  • CM user equipment
  • the modules in the cable modem of the embodiment of the present invention can be combined, divided, and deleted according to actual needs.
  • the cable modem in the embodiment of the present invention can be implemented by a general-purpose integrated circuit, such as a CPU (Central Processing Unit), or an ASIC (Application Specific Integrated Circuit).
  • a general-purpose integrated circuit such as a CPU (Central Processing Unit), or an ASIC (Application Specific Integrated Circuit).
  • 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

本发明实施例公开了一种信号处理方法及相关设备，其中，该方法可以包括：电缆调制解调器在接收到经由功率放大器放大处理的失真信号后，会将其转换为数字信号，并利用补偿系数对其进行非线性补偿，通过这种方式可以在降低HFC网络功耗的同时，能够提高用户端接收信号的质量。进一步的，由于与光节点设备不同距离的CM接收到的信号经过放大处理的次数会有所不同，不同CM接收到的信号的非线性失真程度会有所不同，那么通过本发明实施例，统一由用户端的设备（即CM）对最终的信号进行补偿，在一定程度上可以提高网络服务能力。

Description

一种信号处理方法及相关设备 技术领域
本发明实施例涉及通信技术领域，具体涉及一种信号处理方法及相关设备。
背景技术
功率放大器是指在给定失真率的条件下，能产生最大输出功率以驱动某一负载(如发射机)的放大器，其性能主要包括线性度和效率。其中，线性度是指实际输出功率与理想输出功率的差值占最大输出功率的百分比，其值越小，线性度越好；效率是指输出功率与输入功率的差值占从外部获取的直流总功率的百分比。
图1为功率放大器的特性曲线图，横轴表示输入功率(PIN，单位为dB)，纵轴表示输出功率(POUT，单位为dB)。从图1可知，该特性曲线分为线性区、非线性区和饱和区，随着PIN的增大，POUT在线性区内呈线性增大，在非线性区间内逐渐偏离线性输出值(这种现象也称为非线性失真)，最后在饱和区间内趋于稳定。在非线性区存在1dB工作点P1dB(即实际输出功率偏离理想输出功率为1dB的位置)。P1dB往左，功率放大器的线性度越好，其效率就越低；P1dB往右，功率放大器的效率越高，但其线性度越差(非线性失真越严重)。
光纤同轴混合(Hybrid Fiber Coaxial，HFC)网络是光纤和同轴电缆相结合的混合网络，包括分前端机房、光节点和用户端三个部分。其中，光节点与用户端之间通过同轴电缆连接。通常情况下，从光节点传输到用户端的信号在传输线路中会发生衰减，所以会在传输线路中设置功率放大器，以补偿衰减，但这样就会增加HFC网络的功耗。目前可以通过降低功率放大器的功耗来降低网络功耗，但这样就会降低功率放大器的线性度，使得功率放大器在输入功率不变的情况下工作在非线性区，从而导致用户端接收到的信号非线性失真严重。
发明内容
本发明实施例公开了一种信号处理方法及相关设备，能够在降低HFC网络功耗的前提下，对用户端接收到的信号进行非线性失真补偿，从而提高信号质量。
本发明实施例第一方面公开了一种信号处理方法，应用于HFC网络，该HFC网络包至少一个功率放大器和CM，该方法包括：
CM接收失真信号，其中，该失真信号包括至少一个功率放大器对信号放大后产生的非线性频率成分；
该CM将该失真信号转换为数字信号；
该CM利用补偿系数对该数字信号进行非线性补偿得到补偿信号。
需要说明的是，该非线性频率成分包括三阶交调分量和五阶交调分量中的至少一种，该补偿系数可以为初始化系数，也可以为对该初始化系数不断训练更新得到的系数，还可以为当前系数更新周期内的对初始化系数训练更新达到稳定的系数。
具体的，该CM可以利用补偿系数，并结合LMS算法等实现对数字信号的非线性补偿。
通过这种方式可以在降低HFC网络功耗的同时，能够提高用户端接收信号的质量。进一步的，由于与光节点设备不同距离的CM接收到的信号经过放大处理的次数会有所不同，不同CM接收到的信号的非线性失真程度会有所不同，那么通过本发明实施例，统一由用户端的设备(即CM)对最终的信号进行补偿，在一定程度上可以提高网络服务能力。
可选的，该CM利用补偿系数对该数字信号进行非线性补偿得到补偿信号之后，该方法还可以包括：
该CM将该补偿信号进行信号恢复处理得到参考信号；经信号恢复处理得到的参考信号能够补偿信道响应，从而与光节点设备发出的信号较为接近；
该CM利用该参考信号与补偿信号之间的误差信号训练该补偿系数得到更新系数；
该CM将该补偿系数更新为该更新系数，得到更新后的补偿系数。
通过不断训练更新补偿系数，能够提高对失真信号进行非线性补偿处理的精度，从而可以提高用户端最终接收到的信号质量。
可选的，当HFC网络的下行线路只传输OFDM信号时，该补偿信号为OFDM信号，那么该CM将该补偿信号进行信号恢复处理得到参考信号，包括：
该CM对该OFDM信号进行信号恢复处理得到第一信号；
该CM将该第一信号确定为参考信号。
当HFC网络的下行线路同时传输有OFDM信号和QAM信号时，该补偿信号包括OFDM信号和QAM信号，那么该CM将该补偿信号进行信号恢复处理得到参考信号，包括：
该CM对该OFDM信号进行信号恢复处理得到第一信号，并对QAM信号进行信号恢复处理得到第二信号；
该CM将该第一信号和第二信号合并得到的信号确定为参考信号。
进一步的，由于OFDM信号在传输过程中一般分为多个信道，因此，该OFDM信号一般由多个OFDM信道上承载的OFDM子信号组成，那么该CM对该OFDM信号进行信号恢复处理得到第一信号，包括：
针对每个OFDM信道上承载的OFDM子信号，该CM对该OFDM子信号进行DDC处理，并将DDC处理得到的信号进行FFT处理得到载波信号；
该CM利用导频信号对该载波信号进行FEQ处理，并对FEQ处理得到的信号进行硬判处理得到频域信号；其中，该导频信号包括光节点设备发送给该CM的信号的至少一个频点，该CM在接收失真信号的同时，也会接收到导频信号；
该CM将该频域信号进行IFFT处理，并将IFFT处理得到的信号进行DUC处理得到第一子信号；
该CM将所有OFDM信道上对OFDM子信号处理得到的第一子信号合成得到第一信号。
可选的，由于QAM信号在传输过程中也可以分信道传输，因此，该QAM信号也由至少一个QAM信道上承载的QAM子信号组成。那么该CM对该QAM信号进行信号恢复处理得到第二信号，包括：
针对每个QAM信道上承载的QAM子信号，该CM将该QAM子信号进行DDC处理得到基带信号；
该CM将该基带信号进行TEQ处理，并对TEQ处理得到的信号进行硬判处理得到时域信号；
该CM将该时域信号进行DUC处理得到第二子信号；
该CM将所有QAM信道上对QAM子信号处理得到的第二子信号合成得到第二信号。
可选的，该CM利用该参考信号与补偿信号之间的误差信号训练该补偿系数得到更新系数之后，该方法还可以包括：
该CM获取预先记录的历史误差信号，其中，该历史误差信号为当前补偿系数更新周期内对上一组数字信号进行非线性补偿得到的历史参考信号与历史补偿信号之间的误差信号；
该CM判断该误差信号与该历史误差信号之间的误差是否大于预设误差；
如果该误差小于该预设误差，那么该CM再将该补偿系数更新为该更新系数，从而得到更新后的补偿系数。
可选的，该方法还可以包括：
如果该误差小于或等于预设误差，该CM会将该补偿系数确定为稳定补偿系数，其中，该稳定补偿系数用于对该当前补偿系数更新周期内的数字信号进行非线性补偿。
周期性的对补偿系数更新，并在同一个周期内误差信号稳定的情况下不再对补偿系数进行更新，可以提高非线性补偿的精确度，从而提高用户端接收到的信号质量，并能提高对失真信号进行非线性补偿的效率。
本发明实施例第二方面公开了一种电缆调制解调器CM，应用于HFC网络，该HFC网络还可以包括至少一个功率放大器，该CM包括：
接收模块，用于接收失真信号，其中，该失真信号包括至少一个功率放大器对信号放大后产生的非线性频率成分。
转换模块，用于将上述接收模块接收到的失真信号转换为数字信号。
补偿模块，用于利用补偿系数对该数字信号进行非线性补偿得到补偿信 号。
需要说明的是，该非线性频率成分包括三阶交调分量和五阶交调分量中的至少一种，该补偿系数可以为初始化系数，也可以为对该初始化系数不断训练更新得到的系数，还可以为当前系数更新周期内的对初始化系数训练更新达到稳定的系数。
具体的，补偿模块可以利用补偿系数，并结合LMS算法等实现对数字信号的非线性补偿。
通过这种方式可以在降低HFC网络功耗的同时，能够提高用户端接收信号的质量。进一步的，由于与光节点设备不同距离的CM接收到的信号经过放大处理的次数会有所不同，不同CM接收到的信号的非线性失真程度会有所不同，那么通过本发明实施例，统一由用户端的设备(即CM)对最终的信号进行补偿，在一定程度上可以提高网络服务能力。
可选的，该CM还可以包括：
恢复模块，用于将上述补偿模块进行非线性补偿得到的补偿信号进行信号恢复处理得到参考信号。
其中，经恢复模块进行信号恢复处理得到的参考信号能够补偿信道响应，从而与光节点设备发出的信号较为接近。
训练模块，用于计算上述恢复模块进行信号恢复处理得到的参考信号与上述补偿模块进行非线性补偿得到的补偿信号之间的误差信号，并利用该误差信号训练该补偿系数得到更新系数。
更新模块，用于将该补偿系数更新为上述训练模块训练得到的更新系数，从而得到更新后的补偿系数，其中，该更新后的补偿系数用于对下一组数字信号进行非线性补偿。
通过不断训练更新补偿系数，能够提高对失真信号进行非线性补偿处理的精度，从而可以提高用户端最终接收到的信号质量。
可选的，上述恢复模块可以包括OFDM信号恢复子模块，QAM信号恢复子模块以及确定子模块，其中：
当HFC网络的下行线路只传输OFDM信号时，补偿模块进行非线性补偿得 到的补偿信号为OFDM信号，因此，
上述OFDM信号恢复子模块，用于对该OFDM信号进行信号恢复处理得到第一信号；
上述确定子模块，用于将该第一信号确定为参考信号。
可选的，当HFC网络的下行线路同时传输有OFDM信号和QAM信号时，补偿模块进行非线性补偿得到的补偿信号包括OFDM信号和QAM信号，因此，
上述OFDM信号恢复子模块，用于对该OFDM信号进行信号恢复处理得到第一信号；
同时，上述QAM信号恢复子模块，用于对该QAM信号进行信号恢复处理得到第二信号；
上述确定子模块，用于将该第一信号和第二信号合并得到的信号确定为参考信号。
可选的，由于OFDM信号在传输过程中一般分为多个信道，因此，该OFDM信号一般由多个OFDM信道上承载的OFDM子信号组成，那么上述OFDM信号恢复子模块对该OFDM信号进行信号恢复处理得到第一信号的具体方式可以为：
针对每个OFDM信道上承载的OFDM子信号，对该OFDM子信号进行DDC处理，并将DDC处理得到的信号进行FFT处理得到载波信号；
利用导频信号对该载波信号进行FEQ处理，并对FEQ处理得到的信号进行硬判处理得到频域信号；其中，该导频信号包括光节点设备发送给该CM的信号的至少一个频点，该CM在接收失真信号的同时，也会接收到导频信号；
将该频域信号进行IFFT处理，并将IFFT处理得到的信号进行DUC处理得到第一子信号；
将所有OFDM信道上对OFDM子信号处理得到的第一子信号合成得到第一信号。
可选的，由于QAM信号在传输过程中也可以分信道传输，因此，该QAM信号也由至少一个QAM信道上承载的QAM子信号组成。那么上述QAM信号恢复子模块对该QAM信号进行信号恢复处理得到第二信号的具体方式可以为：
针对每个QAM信道上承载的QAM子信号，将该QAM子信号进行DDC处理得到基带信号；
将该基带信号进行TEQ处理，并对TEQ处理得到的信号进行硬判处理得到时域信号；
将该时域信号进行DUC处理得到第二子信号；
将所有QAM信道上对QAM子信号处理得到的第二子信号合成得到第二信号。
可选的，该CM还可以包括：
获取模块，用于获取预先记录的历史误差信号。
其中，该历史误差信号为当前补偿系数更新周期内对上一组数字信号进行非线性补偿得到的历史参考信号与历史补偿信号之间的误差信号。
判断模块，用于判断上述训练模块得到的误差信号与上述获取模块获取到的历史误差信号之间的误差是否小于预设误差。如果该误差小于该预设误差，那么上述更新模块会将该补偿系数更新为更新系数得到更新后的补偿系数。
可选的，该CM还可以包括：
确定模块，用于在上述判断模块判断出该误差小于或等于预设误差时，将该补偿系数确定为稳定补偿系数，其中，该稳定补偿系数用于对该当前补偿系数更新周期内的数字信号进行非线性补偿。
周期性的对补偿系数更新，并在同一个周期内误差信号稳定的情况下不再对补偿系数进行更新，可以提高非线性补偿的精确度，从而提高用户端接收到的信号质量，并能提高对失真信号进行非线性补偿的效率。
本发明实施例第三方面公开了另一种电缆调制解调器，应用于HFC网络，该HFC网络还可以包括光节点设备和至少一个功率放大器，该电缆调制解调器包括接收器、模数转换器和处理器。其中，该接收器，用于接收由该至少一个功率放大器将该光节点设备发送给电缆调制解调器的信号放大得到的失真信号，模数转换器用于将该失真信号转换为数字信号，而处理器主要用于利用补偿系数对数字信号进行非线性补偿，得到补偿信号，并对该补偿信号进行信号恢复处理，得到参考信号，从而可以利用该参考信号与该补偿信号之间的误差 信号对补偿系数进行训练，并更新。
附图说明
为了更清楚地说明本发明实施例中的技术方案，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是本发明实施例公开的功率放大器的特性曲线图；
图2是本发明实施例公开的一种HFC网络的架构示意图；
图3a是本发明实施例公开的一种信号处理方法的流程示意图；
图3b是本发明实施例公开的失真信号频域示意图；
图4是本发明实施例公开的另一种信号处理方法的流程示意图；
图5是本发明实施例公开的又一种信号处理方法的流程示意图；
图6是本发明实施例公开的一种电缆调制解调器的结构示意图；
图7是本发明实施例公开的另一种电缆调制解调器的结构示意图；
图8是本发明实施例公开的又一种电缆调制解调器的结构示意图。
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做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。
本发明实施例公开了一种信号处理方法及相关设备，能够在降低HFC网络功耗的前提下，对用户端接收到的信号进行非线性失真补偿，从而提高信号质量。以下分别进行详细说明。
为了更好的理解本发明实施例公开的一种信号处理方法及相关设备，下面先对本发明实施例适用的HFC网络架构进行描述。请参阅图2，图2是本发明实施例公开的一种HFC网络的架构示意图。在图2所示的架构中，包括分前端机房、光节点和用户端三个部分，分前端机房与光节点之间通过光纤连接， 光节点与用户端之间通过同轴电缆连接。其中，光节点主要包括分配器和具备将光信号转换为电信号功能和将数字信号转换为模拟信号功能的光节点设备，如同轴媒质转换器(Cable Media Converter，CMC)等；用户端包括CM以及用户终端，如电视机、电脑、电话等。
因此，从有线电视台出来的节目信号(包括各种交互式视频、数据和语音业务等电信号)在分前端机房先转换成光信号在光纤上传输；到光节点后，光节点设备把光信号转换成电信号，经分配器分配后通过同轴电缆送到用户端；到用户端后，CM将电信号进行调制解调，并最终发送到各个用户终端。
具体的，在光节点设备与每个CM之间设置有至少一个功率放大器(Power Amplifier，PA)，PA用于将同轴电缆中传输的信号进行功率放大，以补偿信号在同轴电缆传输过程中的衰减。图2所示的网络架构仅仅给出了部分数量的PA和CM，但PA的具体数量可以根据光节点设备与CM之间的距离来决定，本发明实施例不做限定。
需要说明的是，现有的HFC网络中设有多个功率放大器，加上每个功率放大器的功耗，使得HFC网络中的功耗较大。因此，本发明实施例是在降低HFC网络功耗的前提下提出的，具体通过降低功率放大器的功耗来实现。
基于图2所示的架构，本发明实施例公开了一种信号处理方法。请参阅图3a，图3a是本发明实施例公开的一种信号处理方法的流程示意图。如图3a所示，该信号处理方法可以包括以下步骤：
301、CM接收失真信号。
本发明实施例中，该失真信号是由至少一个功率放大器将光节点设备发送给该CM的信号放大后得到的。具体为：由于光线干线中需要传输光信号，同轴电缆中需要传输电信号，那么光节点设备会将光线干线中接收到的光信号转换为电信号，进一步的，如果该光信号为数字信号，该光节点设备还需要将该转换后的电信号转换为模拟信号，并经由多个功率放大器放大后发送给每个CM；如果该光信号为模拟信号，那么光节点设备就会直接将模块信号经由多个功率放大器放大后发送给每个CM。也就是说，CM接收到的失真信号为模拟信号。
由于本发明实施例在原有的HFC网络的基础上是通过降低功率放大器的功耗来降低网络功耗，但是这样会降低功率放大器的线性度，使得在输入功率不变的情况下，经功率放大器放大处理的信号非线性失真严重。因此，在HFC网络中，CM接收到的信号一般为失真信号。由于每个CM与光节点设备之间的距离不同，每个CM接收到的信号的失真程度也会有所不同。
本发明实施例中，该HFC网络中传输的可以是正交频分复用(Orthogonal Frequency Division Multiplexing，OFDM)信号，也可以是OFDM信号和正交幅度调制(Quadrature Amplitude Modulation，QAM)信号混合的信号，本发明实施例不做限定。
本发明实施例中，光节点设备发送给CM的信号经至少一个功率放大器放大后会产生交调失真，CM最终接收到的失真信号从而会包括非线性频率成分。其中，该非线性频率成分可以包括三阶交调分量和五阶交调分量中的至少一种，如图3b所示。
请一并参阅图3b，图3b是本发明实施例公开的失真信号频域示意图。在HFC网络中传输的信号一般为双频信号，那么该信号经至少一个功率放大器放大后得到的输出信号会产生交调失真，即失真信号相对于光节点设备发出的信号会增加非线性频率成分。在图3b中，宽带信号为光节点设备发送的信号，该宽带信号落在频率ω0-B至ω0+B内，而经至少一个功率放大器放大后，会在宽带信号频率两侧分布有三阶交调分量，即落在频率ω0-3B至ω0+3B内，甚至五阶交调分量，即落在频率ω0-5B至ω0+5B内。其中，三阶交调分量对宽带信号产生的影响最大，五阶交调分量影响次之。
302、该CM将该失真信号转换为数字信号。
本发明实施例中，由于在同轴电缆中传输的信号为模拟信号，因此，CM在对接收到的失真信号进行非线性补偿之前，需要将其进行模数转换(Analog to Digital Converter，ADC)处理，以得到数字信号。
303、该CM利用补偿系数对该数字信号进行非线性补偿得到补偿信号。
本发明实施例中，该补偿系数可以为初始化系数，也可以为对该初始化系数不断训练更新得到的系数，还可以为当前系数更新周期内的对初始化系数训练更新达到稳定的系数，本发明实施例不做限定。
具体的，该CM利用补偿系数对该数字信号进行非线性补偿，得到补偿信号的具体方式可以通过最小均方(Least Mean Square，LMS)算法等实现，从而可以消除失真信号包括的非线性频率成分。
举例来说，以CM利用LMS算法对数字信号进行非线性补偿为例，其具体可以包括以下步骤：
(1)假设补偿系数为w＝[0，0，1，…0]T，数字信号为x[n]，w的长度为L，具体可以为24或者32，本发明实施例不做限定；其中，n为正整数，表示数字信号中有n个数据；
(2)从数字信号x[n]中取一组长度为L的采样值，表示为X[k]＝x[k+pos-1：-1：k-(L-pos)]，其中，k为小于等于n的正整数，表示第k组采样值，也可以表示x[n]中的第k个数据，pos表示补偿系数w中1的位置，例如，当pos＝1时，w＝[1，0，0，…0]T；也就是说，在对x[k]中第1个数据进行非线性补偿时，X[1]＝x[pos：-1：1-(L-pos)]；
(3)利用补偿系数w对采样值X[1]进行非线性补偿，得到补偿后的数据Z[1]＝w*X[1]，由于w＝[0，0，1，…0]T为列向量，X[1]也为列向量，两者点乘得到Z[1]，即为对第1个数据进行非线性补偿后的数据；
(4)在对第2个数据进行非线性补偿时，CM将X[1]中的数据向后移一位得到X[2]，然后利用补偿系数对X[2]进行非线性补偿；其中，该补偿系数可以是对上一组数据进行非线性补偿的补偿系数，也可以为对上一组数据进行非线性补偿的补偿系数进行训练更新后的补偿系数。
可见，在图2所描述的方法中，电缆调制解调器在接收到经由功率放大器放大处理的失真信号后，会将其转换为数字信号，并利用补偿系数对其进行非线性补偿，通过这种方式可以在降低HFC网络功耗的同时，能够提高用户端接收信号的质量。进一步的，由于与光节点设备不同距离的CM接收到的信号经过放大处理的次数会有所不同，不同CM接收到的信号的非线性失真程度会有所不同，那么通过本发明实施例，统一由用户端的设备(即CM)对最终的信号进行补偿，在一定程度上可以提高网络服务能力。
基于图1所示的架构，本发明实施例公开了另一种信号处理方法。请参阅图4，图4是本发明实施例公开的另一种信号处理方法的流程示意图。如图4所示，该信号处理方法可以包括以下步骤：
401、CM接收失真信号。
其中，该失真信号是由至少一个功率放大器将光节点设备发送给该CM的信号放大后得到的，该失真信号包括非线性频率成分。
402、该CM对将该失真信号转换为数字信号。
403、该CM利用补偿系数对该数字信号进行非线性补偿得到补偿信号。
404、该CM将该补偿信号进行信号恢复处理得到参考信号。
本发明实施例中，该CM对ADC处理后的数字信号进行非线性补偿后，会进一步对补偿信号进行信号恢复处理，以补偿信道响应，得到参考信号，该参考信号与光节点设备发出的信号较为接近。
由于HFC网络中既可以传输OFDM信号，又可以同时传输OFDM信号和QAM信号，因此，针对不同的信号，该CM对其进行信号恢复处理的方式不同。
具体实现中，在只传输OFDM信号的场景中(该补偿信号即为OFDM信号)，该CM将该补偿信号进行信号恢复处理，得到参考信号的具体方法可以为：
11)该CM对该OFDM信号进行信号恢复处理得到第一信号；
12)该CM将该第一信号确定为参考信号。
作为一种可行的实施方式，在OFDM信号和QAM信号共存的场景中(该补偿信号同时包括OFDM信号和QAM信号)，该CM将该补偿信号进行信号恢复处理，得到参考信号的具体方法可以为：
21)该CM对该OFDM信号进行信号恢复处理得到第一信号，并对QAM信号进行信号恢复处理得到第二信号；
22)该CM将该第一信号和第二信号合并得到的信号确定为参考信号。
需要说明的是，OFDM技术的主要思想是：先将OFDM信号的频谱划分为若干OFDM信道(如每个信道192MHz)，再将每个OFDM信道分成若干正交的子载波，同时将高速数据信号转换成并行的低速子数据流，将每个子数据流承载在每个子载波上；这里的OFDM信号可以包括一个OFDM信道上承载的OFDM子信号，也可以包括多个OFDM信道上承载的OFDM子信号；因此，该 CM对该OFDM信号进行信号恢复处理得到第一信号的具体方式可以包括以下步骤：
111)针对每个OFDM信道上承载的OFDM子信号，该CM对该OFDM子信号进行数字下变频(Digital Down Converter，DDC)处理，并将DDC处理得到的信号进行快速傅里叶变换(Fast Fourier Transform，FFT)得到载波信号；
112)该CM利用导频信号对该载波信号进行频域均衡(Frequency-domain Equalization，FEQ)处理，并对FEQ处理得到的信号进行硬判处理得到频域信号；
113)该CM将该频域信号进行快速傅里叶逆变换(Invert Fast Fourier Transform，IFFT)，并将IFFT处理得到的信号进行数字上变频(Digital Up Converter，DUC)处理得到第一子信号；
114)该CM将所有OFDM信道上对OFDM子信号处理得到的第一子信号合成得到第一信号。
具体的，针对每一个子信道上承载的OFDM子信号，该CM会利用该OFDM子信号的中心频点对其进行DDC处理，该DDC处理主要包括下搬频和降采样率的操作。其中，下搬频是指将ADC送来的数字信号的有用频谱从中频搬移到基带；降采样率是指将频谱搬移后的数据从ADC的高速采样率降低到一个合适的采样速率水平，通过抽取(Decimation)实现。因此，通过DDC处理可以得到基带时域信号。
进一步的，该CM会将该基带时域信号进行FFT处理，从而将基带时域信号转为频域信号(即载波信号)。该CM在接收失真信号的同时也会接收到一组导频信号，因此，该CM在对该基带时域信号进行FFT处理后，会利用接收到的导频信号对该载波信号进行FEQ处理，以补偿信道响应。其中，导频信号包括了光节点设备发送给该CM的信号中的部分频点，可以是一个，也可以是多个。也就是说，光节点设备在向CM发送信号的同时，会发送一组从该信号提取的部分频点的导频信号，该导频信号同时也包含各个频点在该信号中的位置信息，这样CM就可以利用导频信号与载波信号对应位置的频点之间的误差对该载波信号进行FEQ处理。该CM再将FEQ处理得到的信号进行硬判，从而得到频域信号。其中，对FEQ处理得到的信号进行硬判的原理是将信号中偏离的 频点进行修正。
进一步的，该CM在对FEQ处理得到的信号进行硬判处理后，会将得到的频域信号进行IFFT处理，从而将频域信号转为时域信号。那么，该CM就可以将IFFT处理得到的信号的中心频点对其进行DUC处理，从而得到每个信道的第一子信号。同样的，该DUC处理主要包括升采样率和上搬频的操作。最后，该CM再将每个子信道经过信号恢复处理的第一子信号合并为第一信号，以作为补偿信号对应的参考信号。
可选的，在OFDM信号和QAM信号共存的场景中，该CM对OFDM信号进行信号恢复处理的方式同上。下面对QAM信号进行信号恢复处理的具体方式进行介绍。同样的，由于QAM信号在传输过程中也可以分信道传输，因此，该QAM信号也由至少一个QAM信道上承载的QAM子信号组成。那么CM对QAM信号进行信号恢复处理得到第二信号的具体方式也可以包括以下步骤：
211)针对每个QAM信道上承载的QAM子信号，该CM将该QAM子信号进行DDC处理得到基带信号；
212)该CM将该基带信号进行时域均衡(Time-domain Equalization，TEQ)处理，并对TEQ处理得到的信号进行硬判处理得到时域信号；
213)该CM将该时域信号进行DUC处理得到第二子信号；
214)该CM将所有QAM信道上对QAM子信号处理得到的第二子信号合成得到第二信号。
具体的，针对每一个QAM信道上承载的QAM子信号，该CM首先会对其进行DDC处理，即进行下搬频和降采样率处理，同样得到基带时域信号，然后再将基带时域信号进行TEQ处理，以补偿信道响应。
进一步的，该CM会将TEQ处理得到的信号进行硬判处理，从而得到时域信号，并将该时域信号进行DUC处理(升采样率和上搬频)，从而得到第二子信号。最终该CM会将所有QAM信道经信号恢复处理后得到的第二子信号进行合成，从而得到第二信号。那么，第二信号和第一信号合成的信号即可作为补偿信号对应的参考信号。
405、该CM利用该参考信号与补偿信号之间的误差信号训练该补偿系数得到更新系数。
本发明实施例中，CM在对补偿信号进行信号恢复处理得到参考信号后，可以计算出该参考信号与该补偿信号之间的误差，从而得到误差信号，然后再利用该误差信号训练该补偿系数，从而得到一组更新系数。
具体的，该CM利用误差信号训练该补偿系数得到更新系数的具体方式可以为：假设数字信号用x[n]表示，每次从x[n]中取长度为L的数据进行非线性补偿，第k组信号用X[k]表示，利用补偿系数w(k)对X[k]进行非线性补偿得到补偿信号z[k]，该补偿信号z[k]即为对x[n]中第k个数据进行非线性补偿得到的信号，对z[k]进行信号恢复处理得到参考信号d[k]，w(k)表示对第k组数据进行非线性补偿的补偿系数，为L行，1列的列向量，那么更新系数q可以用下列计算公式得到，即q＝w(k)+2*mu*conj(e[k])*X[k]。其中，e[k]＝d[k]-z[k]即表示误差信号。mu为预设系数，为固定值，conj(e[k])表示取误差信号e[k]的共轭。
406、该CM将该补偿系数更新为该更新系数得到更新后的补偿系数。
本发明实施例中，该CM利用误差信号训练该补偿系数，得到更新系数后，可以将当前使用的补偿系数更新为该更新系数。这样在对下一组数字信号进行非线性补偿时，该CM就可以利用更新后的补偿系数对其进行非线性补偿，即w(k+1)＝q＝w(k)+2*mu*conj(e[k])*X[k]。也就是说，对本组数字信号进行非线性补偿的补偿系数是由上一次训练系数得到的。
举例来说，假设在对第一组信号进行非线性补偿时，使用的补偿系数为预先设置的初始化系数，记为w(1)，CM在对第一组信号非线性补偿后，会对该初始化系数进行训练更新，得到更新后的补偿系数，记为w(2)，那么该CM就可以使用w(2)对第二组信号进行非线性补偿。由此可见，该CM在对第k组信号进行非线性补偿时使用的是第k-1次更新后的补偿系数w(k)。
可见，在图4所描述的方法中，当CM对第k组信号进行非线性补偿时，该CM利用第k-1次更新后的补偿系数对其进行非线性补偿，然后通过信号恢复处理得到参考信号，并利用参考信号与补偿信号之间的误差信号训练该第k-1次更新后的补偿系数，得到的更新系数即可作为对第k+1组信号进行非线性补偿处理的补偿系数。通过不断训练更新补偿系数，能够提高对失真信号进行非线性补偿处理的精度，从而可以提高用户端最终接收到的信号质量。
基于图1所示的架构，本发明实施例公开了又一种信号处理方法。请参阅图5，图5是本发明实施例公开的又一种信号处理方法的流程示意图。如图5所示，该信号处理方法可以包括以下步骤：
501、CM接收失真信号。
其中，该失真信号是由至少一个功率放大器将光节点设备发送给该CM的信号放大后得到的，该失真信号包括非线性频率成分。
502、该CM对将该失真信号转换为数字信号。
503、该CM利用补偿系数对该数字信号进行非线性补偿得到补偿信号。
504、该CM将该补偿信号进行信号恢复处理得到参考信号。
505、该CM利用该参考信号与补偿信号之间的误差信号训练该补偿系数得到更新系数。
本发明实施例中，该CM在利用该误差信号训练该补偿系数后，会记录该误差信号，以便于确定非线性补偿得到的补偿信号是否稳定。
506、该CM获取预先记录的历史误差信号。
本发明实施例中，该历史误差信号为当前补偿系数更新周期内对上一组数字信号进行非线性补偿得到的历史参考信号与历史补偿信号之间的误差信号。也就是说，该CM会周期性的对补偿系数进行更新。其中，补偿系数更新周期可以为10ms，本发明实施例不做限定。
需要说明的是，如果该更新系数是当前补偿系数更新周期内第一次对补偿系数进行训练得到的，那么该CM会在得到该更新系数后，直接将该补偿系数更新为该更新系数，并在接收下一组失真信号后，利用该更新后的补偿系数对其进行非线性补偿；如果该更新系数是当前补偿系数更新周期内第k次对补偿系数进行训练得到的更新的补偿系数，其中，k为大于等于2的正整数，那么该CM会先获取第k-1次对数字信号非线性补偿处理得到的历史参考信号与历史补偿信号之间的历史误差信号。
507、该CM判断该误差信号与该历史误差信号之间的误差是否大于预设误差，若是，执行步骤508；若否，执行步骤509。
本发明实施例中，该CM在获取到历史误差信号后，会计算该误差信号与该历史误差信号之间的误差，从而通过判断该预设是否大于预设误差来确定进 行非线性补偿后的补偿信号是否稳定。
也就是说，如果上一组非线性补偿后得到的补偿信号与参考信号的误差信号与本组非线性补偿后得到的补偿信号与参考信号的误差信号误差较小(即该误差小于或等于预设误差)，那么该CM即可视为当前的补偿系数对数字信号进行非线性补偿较为稳定，从而可以在当前补偿系数更新周期内不再对补偿系数进行更新；如果上一组非线性补偿后得到的补偿信号与参考信号的误差信号与本组非线性补偿后得到的补偿信号与参考信号的误差信号误差较大(即该误差大于预设误差)，那么该CM会将当前的补偿系数更新为该更新系数。通过这种方式对补偿系数进行循环更新，直到最终得到的误差信号稳定为止。
508、该CM将该补偿系数更新为该更新系数得到更新后的补偿系数。
其中，该更新后的补偿系数用于对下一组数字信号进行非线性补偿。
509、该CM将该补偿系数确定为稳定补偿系数。
本发明实施例中，该稳定补偿系数用于对当前补偿系数更新周期内的所有数字信号进行非线性补偿。也即是说，如果该误差信号小于历史误差信号，该CM可以视为非线性补偿得到的补偿信号与参考信号之间的误差趋于稳定，为了提高对信号的非线性补偿效率，该CM在当前补偿系数更新周期内不再更新补偿系数。
进一步的，如果在下一补偿系数更新周期开始时，该CM会再次对补偿系数进行更新，直到误差信号稳定为止。需要说明的是，在下一补偿系数更新周期开始时，进行非线性补偿处理的补偿系数可以为预设的初始化系数，也可以为当前补偿系数更新周期内得到的稳定补偿系数，本发明实施例不做限定。
举例来说，假设在当前补偿系数更新周期内第一次对数字信号进行非线性补偿，那么补偿系数可以为预设的初始化系数q1。如果在第k次对数字信号进行非线性补偿后，补偿信号与参考信号的误差信号与第k-1次非线性补偿得到的历史误差信号之间的误差较小，那么该CM就可以将当前使用的补偿系数qk-1作为本周期内的稳定补偿系数。该CM在本周期内均使用qk-1对失真信号进行模数转换后的数字信号进行非线性补偿。进一步的，在下一补偿系数更新周期到来时，该CM会再次对补偿系数进行更新，那么第一次对失真信号进行模数转换后的数字信号进行非线性补偿使用的补偿系数既可以为qk-1，也可以 为初始化系数q1，本发明实施例不做限定。
可见，在图5所描述的方法中，该CM会周期性的对补偿系数进行更新，在同一周期内，如果使用的补偿系数对数字信号进行非线性补偿得到的补偿信号与参考信号之间的误差信号较为稳定，那么该CM在当前周期内就不会在对补偿系数进行更新，从而在当前周期内一直使用该补偿系数对数字信号进行非线性补偿；如果使用的补偿系数对数字信号进行非线性补偿得到的补偿信号与参考信号之间的误差信号不稳定，那么该CM会不断对补偿系数进行更新，直到误差信号稳定为止。周期性的对补偿系数更新，并在同一个周期内误差信号稳定的情况下不再对补偿系数进行更新，可以提高非线性补偿的精确度，从而提高用户端接收到的信号质量，并能提高对失真信号进行非线性补偿的效率。
基于图1所示的架构，本发明实施例公开了一种电缆调制解调器。请参阅图6，图6是本发明实施例公开的一种电缆调制解调器的结构示意图。如图6所示，该CM可以包括：
接收模块601，用于接收失真信号；其中，该失真信号由HFC网络中至少一个功率放大器将光节点设备发送给该CM的信号放大后得到，该失真信号包括非线性频率成分，且该非线性频率成分包括三阶交调分量和五阶交调分量中的至少一种。
转换模块602，用于将上述接收模块601接收到的失真信号转换为数字信号。
补偿模块603，用于利用补偿系数对该数字信号进行非线性补偿得到补偿信号，以消除非线性频率成分。
本发明实施例中，该补偿系数可以为初始化系数，也可以为对该初始化系数不断训练更新得到的系数，还可以为当前系数更新周期内的对初始化系数训练更新达到稳定的系数，本发明实施例不做限定。
具体的，补偿模块603可以利用补偿系数，并结合LMS算法等实现对数字信号的非线性补偿。
请一并参阅图7，图7是本发明实施例公开的另一种电缆调制解调器的结构 示意图。其中，图7所示的CM是在图6所示的CM的基础上优化得到的。如图7所示，该CM还可以包括：
恢复模块604，用于将上述补偿模块603进行非线性补偿得到的补偿信号进行信号恢复处理得到参考信号。
本发明实施例中，经恢复模块604进行信号恢复处理得到的参考信号能够补偿信道响应，从而与光节点设备发出的信号较为接近。
训练模块605，用于计算上述恢复模块604进行信号恢复处理得到的参考信号与上述补偿模块603进行非线性补偿得到的补偿信号之间的误差信号，并利用该误差信号训练该补偿系数得到更新系数。
更新模块606，用于将该补偿系数更新为上述训练模块605训练得到的更新系数，从而得到更新后的补偿系数，其中，该更新后的补偿系数用于对下一组数字信号进行非线性补偿。
也就是说，更新模块606在将该补偿系数更新为该更新系数，得到更新后的补偿系数后，补偿模块602会利用该更新后的补偿系数对下一组数字信号进行非线性补偿。
通过不断训练更新补偿系数，能够提高对失真信号进行非线性补偿处理的精度，从而可以提高用户端最终接收到的信号质量。
作为一种可行的实施方式，上述恢复模块604可以包括OFDM信号恢复子模块6041，QAM信号恢复子模块6042以及确定子模块6043，其中：
当HFC网络的下行线路只传输OFDM信号时，补偿模块603进行非线性补偿得到的补偿信号为OFDM信号，因此，
上述OFDM信号恢复子模块6041，用于对该OFDM信号进行信号恢复处理得到第一信号；
上述确定子模块6043，用于将该第一信号确定为参考信号。
当HFC网络的下行线路同时传输有OFDM信号和QAM信号时，补偿模块603进行非线性补偿得到的补偿信号包括OFDM信号和QAM信号，因此，
上述OFDM信号恢复子模块6041，用于对该OFDM信号进行信号恢复处理 得到第一信号；
同时，上述QAM信号恢复子模块602，用于对该QAM信号进行信号恢复处理得到第二信号；
上述确定子模块6043，用于将该第一信号和第二信号合并得到的信号确定为参考信号。
进一步的，由于OFDM信号在传输过程中一般分为多个信道，因此，该OFDM信号一般由多个OFDM信道上承载的OFDM子信号组成，那么上述OFDM信号恢复子模块6041对该OFDM信号进行信号恢复处理得到第一信号的具体方式可以为：
针对每个OFDM信道上承载的OFDM子信号，对该OFDM子信号进行DDC处理，并将DDC处理得到的信号进行FFT处理得到载波信号；
利用导频信号对该载波信号进行FEQ处理，并对FEQ处理得到的信号进行硬判处理得到频域信号；其中，该导频信号包括光节点设备发送给该CM的信号的至少一个频点，该CM在接收失真信号的同时，也会接收到导频信号；
将该频域信号进行IFFT处理，并将IFFT处理得到的信号进行DUC处理得到第一子信号；
将所有OFDM信道上对OFDM子信号处理得到的第一子信号合成得到第一信号。
可选的，由于QAM信号在传输过程中也可以分信道传输，因此，该QAM信号也由至少一个QAM信道上承载的QAM子信号组成。那么上述QAM信号恢复子模块6042对该QAM信号进行信号恢复处理得到第二信号的具体方式可以为：
针对每个QAM信道上承载的QAM子信号，将该QAM子信号进行DDC处理得到基带信号；
将该基带信号进行TEQ处理，并对TEQ处理得到的信号进行硬判处理得到时域信号；
将该时域信号进行DUC处理得到第二子信号；
将所有QAM信道上对QAM子信号处理得到的第二子信号合成得到第二 信号。
作为另一种可行的实施方式，该CM还可以包括：
获取模块607，用于获取预先记录的历史误差信号。
其中，该历史误差信号为当前补偿系数更新周期内对上一组数字信号进行非线性补偿得到的历史参考信号与历史补偿信号之间的误差信号。也就是说，该CM会周期性的对补偿系数进行更新。其中，补偿系数更新周期可以为10ms，本发明实施例不做限定。
判断模块608，用于判断上述训练模块605得到的误差信号与上述获取模块607获取到的历史误差信号之间的误差是否小于预设误差。如果该误差小于该预设误差，那么上述更新模块606会将该补偿系数更新为更新系数得到更新后的补偿系数。
作为又一种可行的实施方式，该CM还可以包括：
确定模块609，用于在上述判断模块608判断出该误差小于或等于预设误差时，将该补偿系数确定为稳定补偿系数，其中，该稳定补偿系数用于对该当前补偿系数更新周期内的数字信号进行非线性补偿。
也就是说，确定模块609在将该补偿系数确定为稳定补偿系数后，补偿模块602在当前补偿系数更新周期内会利用该稳定补偿系数对数字信号进行非线性补偿。
周期性的对补偿系数更新，并在同一个周期内误差信号稳定的情况下不再对补偿系数进行更新，可以提高非线性补偿的精确度，从而提高用户端接收到的信号质量，并能提高对失真信号进行非线性补偿的效率。
可见，在图6和图7所描述的电缆调制解调器中，电缆调制解调器在接收到经由功率放大器放大处理的失真信号后，会将其转换为数字信号，并利用补偿系数对其进行非线性补偿，通过这种方式可以在降低HFC网络功耗的同时，能够提高用户端接收信号的质量。进一步的，由于与光节点设备不同距离的CM接收到的信号经过放大处理的次数会有所不同，不同CM接收到的信号的非线性失真程度会有所不同，那么通过本发明实施例，统一由用户端的设备(即 CM)对最终的信号进行补偿，在一定程度上可以提高网络服务能力。
请参阅图8，图8是本发明实施例公开的又一种电缆调制解调器的结构示意图。其中，图8所描述的CM可以包括接收器801、模数转换器802、至少一个处理器803、发送器804以及通信总线805，其中：
上述发送器804，用于将经CM进行信号非线性补偿的补偿信号发送到用户端的各个用户终端。
上述通信总线805用于实现上述接收器801、上述模数转换器802、上述处理器803、上述接收器904以及上述发送器804这些组件之间的通信连接。其中：
上述接收器801，用于接收失真信号；其中，该失真信号由HFC网络中至少一个功率放大器将光节点设备发送给该CM的信号放大后得到，该失真信号包括非线性频率成分，且该非线性频率成分包括三阶交调分量和五阶交调分量中的至少一种。
上述模数转换器802，用于将上述接收器801接收到的失真信号转换为数字信号。
上述处理器803，用于利用补偿系数对该数字信号进行非线性补偿得到补偿信号，以消除非线性频率成分。
本发明实施例中，该补偿系数可以为初始化系数，也可以为对该初始化系数不断训练更新得到的系数，还可以为当前系数更新周期内的对初始化系数训练更新达到稳定的系数，本发明实施例不做限定。
具体的，上述处理器803可以利用补偿系数，并结合LMS算法等实现对数字信号的非线性补偿。
作为一种可行的实施方式，上述处理器803，还用于在利用补偿系数对该数字信号进行非线性补偿得到补偿信号后，将该补偿信号进行信号恢复处理得到参考信号，利用该参考信号与该补偿信号之间的误差信号训练该补偿系数得到更新系数，并将该补偿系数更新为该更新系数得到更新后的补偿系数，其中，该更新后的补偿系数用于对下一组数字信号进行非线性补偿。
通过不断训练更新补偿系数，能够提高对失真信号进行非线性补偿处理的精度，从而可以提高用户端最终接收到的信号质量。
作为另一种可行的实施方式，当HFC网络的下行线路只传输OFDM信号时，该补偿信号为OFDM信号，那么，
上述处理器803将该补偿信号进行信号恢复处理得到参考信号的具体方式可以为：
对该OFDM信号进行信号恢复处理得到第一信号；
将该第一信号确定为参考信号。
作为又一种可行的实施方式，当HFC网络的下行线路同时传输有OFDM信号和QAM信号时，该补偿信号包括OFDM信号和QAM信号，那么，
上述处理器803将该补偿信号进行信号恢复处理得到参考信号的具体方式可以为：
对该OFDM信号进行信号恢复处理得到第一信号，并对该QAM信号进行信号恢复处理得到第二信号；
将该第一信号和第二信号合并得到的信号确定为参考信号。
作为又一种可行的实施方式，由于OFDM信号在传输过程中一般分为多个信道，因此，该OFDM信号一般由多个OFDM信道上承载的OFDM子信号组成，那么上述处理器803对该OFDM信号进行信号恢复处理得到第一信号的具体方式可以为：
针对每个OFDM信道上承载的OFDM子信号，对该OFDM子信号进行DDC处理，并将DDC处理得到的信号进行FFT处理，得到载波信号；
利用导频信号对该载波信号进行FEQ处理，并对FEQ处理得到的信号进行硬判处理得到频域信号；其中，该导频信号包括光节点设备发送给该CM的信号的至少一个频点，该CM在接收失真信号的同时，也会接收到导频信号；
将该频域信号进行IFFT处理，并将IFFT处理得到的信号进行DUC处理得到第一子信号；
将所有OFDM信道上对OFDM子信号处理得到的第一子信号合成得到第一信号。
作为又一种可行的实施方式，由于QAM信号在传输过程中也可以分信道传输，因此，该QAM信号也由至少一个QAM信道上承载的QAM子信号组成。那么上述处理器803对该QAM信号进行信号恢复处理得到第二信号的具体方式可以为：
针对每个QAM信道上承载的QAM子信号，将该QAM子信号进行DDC处理得到基带信号；
将该基带信号进行TEQ处理，并对TEQ处理得到的信号进行硬判处理得到时域信号；
将该时域信号进行DUC处理得到第二子信号；
将所有QAM信道上对QAM子信号处理得到的第二子信号合成得到第二信号。
作为又一种可行的实施方式，上述处理器803，还用于在利用该参考信号与该补偿信号之间的误差信号对该补偿系数进行训练得到更新系数后，获取预先记录的历史误差信号，并判断该误差信号与该历史误差信号之间的误差是否大于预设误差；
其中，该历史误差信号为当前补偿系数更新周期内对上一组数字信号进行非线性补偿得到的历史参考信号与历史补偿信号之间的误差信号。也就是说，该CM会周期性的对补偿系数进行更新。其中，补偿系数更新周期可以为10ms，本发明实施例不做限定。
那么上述处理器803将该补偿系数更新为该更新系数得到更新后的补偿系数的具体方式为：
在该误差大于该预设误差时，将该补偿系数更新为该更新系数得到更新后的补偿系数。
作为又一种可行的实施方式，上述处理器803，还用于在该误差小于或等于该预设误差时，将该补偿系数确定为稳定补偿系数，其中，该稳定补偿系数用于对该当前补偿系数更新周期内的数字信号进行非线性补偿。
周期性的对补偿系数更新，并在同一个周期内误差信号稳定的情况下不再对补偿系数进行更新，可以提高非线性补偿的精确度，从而提高用户端接收到 的信号质量，并能提高对失真信号进行非线性补偿的效率。
可见，在图9所描述的电缆调制解调器中，电缆调制解调器在接收到经由功率放大器放大处理的失真信号后，会将其转换为数字信号，并利用补偿系数对其进行非线性补偿，通过这种方式可以在降低HFC网络功耗的同时，能够提高用户端接收信号的质量。进一步的，由于与光节点设备不同距离的CM接收到的信号经过放大处理的次数会有所不同，不同CM接收到的信号的非线性失真程度会有所不同，那么通过本发明实施例，统一由用户端的设备(即CM)对最终的信号进行补偿，在一定程度上可以提高网络服务能力。
需要说明的是，在上述实施例中，对各个实施例的描述都各有侧重，某个实施例中没有详细描述的部分，可以参见其他实施例的相关描述。其次，本领域技术人员也应该知悉，说明书中所描述的实施例均属于优选实施例，所涉及的动作和模块并不一定是本发明所必须的。
本发明实施例方法中的步骤可以根据实际需要进行顺序调整、合并和删减。
本发明实施例电缆调制解调器中的模块可以根据实际需要进行合并、划分和删减。
本发明实施例中所述电缆调制解调器，可以通过通用集成电路，例如CPU(Central Processing Unit，中央处理器)，或通过ASIC(Application Specific Integrated Circuit，专用集成电路)来实现。
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。
以上对本发明实施例公开的一种信号处理方法及相关设备进行了详细介绍，本文中应用了具体实例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本发明的限制。

Claims (27)

  1. 一种信号处理方法，应用于光纤同轴混合HFC网络，所述HFC网络包括至少一个功率放大器和电缆调制解调器CM，其特征在于，所述方法包括：
    所述CM接收失真信号，所述失真信号包括所述至少一个功率放大器对信号放大后产生的非线性频率成分；
    所述CM将所述失真信号转换为数字信号；
    所述CM利用补偿系数对所述数字信号进行非线性补偿得到补偿信号。
  2. 根据权利要求1所述的方法，其特征在于，所述非线性频率成分包括三阶交调分量和五阶交调分量中的至少一种。
  3. 根据权利要求1或2所述的方法，其特征在于，所述CM利用补偿系数对所述数字进行非线性补偿得到补偿信号之后，所述方法还包括：
    所述CM将所述补偿信号进行信号恢复处理得到参考信号；
    所述CM利用所述参考信号与所述补偿信号之间的误差信号训练所述补偿系数得到更新系数；
    所述CM将所述补偿系数更新为所述更新系数得到更新后的补偿系数，所述更新后的补偿系数用于对下一组数字信号进行非线性补偿。
  4. 根据权利要求3所述的方法，其特征在于，所述补偿信号包括正交频分复用OFDM信号，所述CM将所述补偿信号进行信号恢复处理得到参考信号，包括：
    所述CM对所述OFDM信号进行信号恢复处理得到第一信号；
    所述CM将所述第一信号确定为参考信号。
  5. 根据权利要求3所述的方法，其特征在于，所述补偿信号包括OFDM信号和正交幅度调制QAM信号，所述CM将所述补偿信号进行信号恢复处理得到参考信号，包括：
    所述CM对所述OFDM信号进行信号恢复处理得到第一信号，并对所述 QAM信号进行信号恢复处理得到第二信号；
    所述CM将所述第一信号和所述第二信号合并得到的信号确定为参考信号。
  6. 根据权利要求4或5所述的方法，其特征在于，所述OFDM信号由至少一个OFDM信道上承载的OFDM子信号组成，所述CM对所述OFDM信号进行信号恢复处理得到第一信号，包括：
    所述CM将每个OFDM信道上承载的OFDM子信号进行数字下变频DDC处理，并将DDC处理得到的信号进行快速傅里叶变换FFT得到载波信号；
    所述CM利用导频信号对所述载波信号进行频域均衡FEQ处理，并对FEQ处理得到的信号进行硬判处理得到频域信号，所述导频信号包括所述光节点设备发送给所述CM的信号的至少一个频点；
    所述CM将所述频域信号进行快速傅里叶逆变换IFFT，并将IFFT处理得到的信号进行数字上变频DUC处理得到第一子信号；
    所述CM将所有的所述第一子信号合成得到第一信号。
  7. 根据权利要求5所述的方法，其特征在于，所述QAM信号由至少一个QAM信道上承载的QAM子信号组成，所述CM对所述QAM信号进行信号恢复处理得到第二信号，包括：
    所述CM将每个QAM信道上承载的QAM子信号进行DDC处理得到基带信号；
    所述CM对所述基带信号进行时域均衡TEQ处理，并对TEQ处理得到的信号进行硬判处理得到时域信号；
    所述CM将所述时域信号进行DUC处理得到第二子信号；
    所述CM将所有的所述第二子信号合成得到第二信号。
  8. 根据权利要求3～7任一项所述的方法，其特征在于，所述CM利用所述参考信号与所述补偿信号之间的误差信号对所述补偿系数进行训练得到更新系数之后，所述方法还包括：
    所述CM获取预先记录的历史误差信号，所述历史误差信号为当前补偿系数更新周期内对上一组数字信号进行非线性补偿得到的历史参考信号与历史补偿信号之间的误差信号；
    所述CM判断所述误差信号与所述历史误差信号之间的误差是否大于预设误差；
    所述CM将所述补偿系数更新为所述更新系数得到更新后的补偿系数，包括：
    如果所述误差大于所述预设误差，所述CM将所述补偿系数更新为所述更新系数得到更新后的补偿系数。
  9. 根据权利要求8所述的方法，其特征在于，所述方法还包括：
    如果所述误差小于或等于所述预设误差，所述CM将所述补偿系数确定为稳定补偿系数，所述稳定补偿系数用于对所述当前补偿系数更新周期内的数字信号进行非线性补偿。
  10. 一种CM，应用于HFC网络，所述HFC网络还包括至少一个功率放大器，其特征在于，所述CM包括：
    接收模块，用于接收失真信号，所述失真信号包括所述至少一个功率放大器对信号放大后产生的非线性频率成分；
    转换模块，用于将所述失真信号转换为数字信号；
    补偿模块，用于利用补偿系数对所述数字信号进行非线性补偿得到补偿信号。
  11. 根据权利要求10所述的CM，其特征在于，所述非线性频率成分包括三阶交调分量和五阶交调分量中的至少一种。
  12. 根据权利要求10或11所述的CM，其特征在于，所述CM还包括：
    恢复模块，用于将所述补偿信号进行信号恢复处理得到参考信号；
    训练模块，用于利用所述参考信号与所述补偿信号之间的误差信号训练所述补偿系数得到更新系数；
    更新模块，用于将所述补偿系数更新为所述更新系数得到更新后的补偿系数，所述更新后的补偿系数用于对下一组数字信号进行非线性补偿。
  13. 根据权利要求12所述的CM，其特征在于，所述补偿信号包括OFDM信号，所述恢复模块包括OFDM信号恢复子模块和第一确定子模块，其中：
    所述OFDM信号恢复子模块，用于对所述OFDM信号进行信号恢复处理得到第一信号；
    所述第一确定子模块，用于将所述第一信号确定为参考信号。
  14. 根据权利要求12所述的CM，其特征在于，所述补偿信号包括OFDM信号和QAM信号，所述恢复模块包括OFDM信号恢复子模块、QAM信号恢复子模块和第二确定子模块，其中：
    所述OFDM信号恢复子模块，用于对所述OFDM信号进行信号恢复处理得到第一信号；
    所述QAM信号恢复子模块，用于对所述QAM信号进行信号恢复处理得到第二信号；
    所述第二确定子模块，用于将所述第一信号和所述第二信号合并得到的信号确定为参考信号。
  15. 根据权利要求13或14所述的CM，其特征在于，所述OFDM信号由至少一个OFDM信道上承载的OFDM子信号组成，所述OFDM信号恢复子模块对所述OFDM信号进行信号恢复处理得到第一信号的具体方式为：
    将每个OFDM信道上承载的OFDM子信号进行DDC处理，并将DDC处理得到的信号进行FFT得到载波信号；
    利用导频信号对所述载波信号进行FEQ处理，并对FEQ处理得到的信号进行硬判处理得到频域信号，所述导频信号包括所述光节点设备发送给所述CM的信号的至少一个频点；
    将所述频域信号进行IFFT，并将IFFT处理得到的信号进行数字上变频DUC处理得到第一子信号；
    将所有的所述第一子信号合成得到第一信号。
  16. 根据权利要求14所述的CM，其特征在于，所述QAM信号由至少一个QAM信道上承载的QAM子信号组成，所述QAM信号恢复子模块对所述QAM信号进行信号恢复处理得到第二信号的具体方式为：
    将每个QAM信道上承载的QAM子信号进行DDC处理得到基带信号；
    对所述基带信号进行TEQ处理，并对TEQ处理得到的信号进行硬判处理得到时域信号；
    将所述时域信号进行DUC处理得到第二子信号；
    将所有的所述第二子信号合成得到第二信号。
  17. 根据权利要求12～16任一项所述的CM，其特征在于，所述CM还包括：
    获取模块，用于获取预先记录的历史误差信号，所述历史误差信号为当前补偿系数更新周期内对上一组数字信号进行非线性补偿得到的历史参考信号与历史补偿信号之间的误差信号；
    判断模块，用于判断所述误差信号与所述历史误差信号之间的误差是否大于预设误差；
    所述更新模块将所述补偿系数更新为所述更新系数得到更新后的补偿系数的具体方式为：
    在所述判断模块判断出所述误差大于所述预设误差时，将所述补偿系数更新为所述更新系数得到更新后的补偿系数。
  18. 根据权利要求17所述的CM，其特征在于，所述CM还包括：
    确定模块，用于在所述判断模块判断出所述误差小于或等于所述预设误差时，将所述补偿系数确定为稳定补偿系数，所述稳定补偿系数用于对所述当前补偿系数更新周期内的数字信号进行非线性补偿。
  19. 一种CM，应用于HFC网络，所述HFC网络还包括至少一个功率放大器，其特征在于，所述CM包括：
    接收器，用于接收失真信号，所述失真信号包括所述至少一个功率放大器对信号放大后产生的非线性频率成分；
    模数转换器，用于将所述失真信号转换为数字信号；
    处理器，用于利用补偿系数对所述数字信号进行非线性补偿得到补偿信号。
  20. 根据权利要求19所述的CM，其特征在于，所述非线性频率成分包括三阶交调分量和五阶交调分量中的至少一种。
  21. 根据权利要求19或20所述的CM，其特征在于，
    所述处理器，还用于在利用补偿系数对所述数字信号进行非线性补偿得到补偿信号后，将所述补偿信号进行信号恢复处理得到参考信号，利用所述参考信号与所述补偿信号之间的误差信号训练所述补偿系数得到更新系数，并将所述补偿系数更新为所述更新系数得到更新后的补偿系数，所述更新后的补偿系数用于对下一组数字信号进行非线性补偿。
  22. 根据权利要求21所述的CM，其特征在于，所述补偿信号包括OFDM信号，所述处理器将所述补偿信号进行信号恢复处理得到参考信号的具体方式为：
    对所述OFDM信号进行信号恢复处理得到第一信号；
    将所述第一信号确定为参考信号。
  23. 根据权利要求21所述的CM，其特征在于，所述补偿信号包括OFDM信号和QAM信号，所述处理器将所述补偿信号进行信号恢复处理得到参考信号的具体方式为：
    对所述OFDM信号进行信号恢复处理得到第一信号，并对所述QAM信号进行信号恢复处理得到第二信号；
    将所述第一信号和所述第二信号合并得到的信号确定为参考信号。
  24. 根据权利要求22或23所述的CM，其特征在于，所述OFDM信号由至少一个OFDM信道上承载的OFDM子信号组成，所述处理器对所述OFDM信号进行信号恢复处理得到第一信号的具体方式为：
    将每个OFDM信道上承载的OFDM子信号进行DDC处理，并将DDC处理得到的信号进行FFT得到载波信号；
    利用导频信号对所述载波信号进行FEQ处理，并对FEQ处理得到的信号进行硬判处理得到频域信号，所述导频信号包括所述光节点设备发送给所述CM的信号的至少一个频点；
    将所述频域信号进行IFFT，并将IFFT处理得到的信号进行数字上变频DUC处理得到第一子信号；
    将所有的所述第一子信号合成得到第一信号。
  25. 根据权利要求23所述的CM，其特征在于，所述QAM信号由至少一个QAM信道上承载的QAM子信号组成，所述处理器对所述QAM信号进行信号恢复处理得到第二信号的具体方式为：
    将每个QAM信道上承载的QAM子信号进行DDC处理得到基带信号；
    对所述基带信号进行TEQ处理，并对TEQ处理得到的信号进行硬判处理得到时域信号；
    将所述时域信号进行DUC处理得到第二子信号；
    将所有的所述第二子信号合成得到第二信号。
  26. 根据权利要求21～25任一项所述的CM，其特征在于，
    所述处理器，还用于在利用所述参考信号与所述补偿信号之间的误差信号对所述补偿系数进行训练得到更新系数后，获取预先记录的历史误差信号，并判断所述误差信号与所述历史误差信号之间的误差是否大于预设误差，其中，所述历史误差信号为当前补偿系数更新周期内对上一组数字信号进行非线性补偿得到的历史参考信号与历史补偿信号之间的误差信号；
    所述处理器将所述补偿系数更新为所述更新系数得到更新后的补偿系数的具体方式为：
    在所述误差大于所述预设误差时，将所述补偿系数更新为所述更新系数得到更新后的补偿系数。
  27. 根据权利要求26所述的CM，其特征在于，
    所述处理器，还用于在所述误差小于或等于所述预设误差时，将所述补偿系数确定为稳定补偿系数，所述稳定补偿系数用于对所述当前补偿系数更新周期内的数字信号进行非线性补偿。
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