WO2024067173A1 - 基于高斯近似改进极化码的译码级联迭代水声通信系统 - Google Patents

基于高斯近似改进极化码的译码级联迭代水声通信系统 Download PDF

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WO2024067173A1
WO2024067173A1 PCT/CN2023/119205 CN2023119205W WO2024067173A1 WO 2024067173 A1 WO2024067173 A1 WO 2024067173A1 CN 2023119205 W CN2023119205 W CN 2023119205W WO 2024067173 A1 WO2024067173 A1 WO 2024067173A1
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channel
signal
gaussian approximation
underwater acoustic
decoding
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PCT/CN2023/119205
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English (en)
French (fr)
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吴金秋
陈柔池
齐晓飞
左大鸿
张文博
周佳琼
赵志伟
赵庆超
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鹏城实验室
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0056—Systems characterized by the type of code used
    • H04L1/0057—Block codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B11/00—Transmission systems employing sonic, ultrasonic or infrasonic waves
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B13/00—Transmission systems characterised by the medium used for transmission, not provided for in groups H04B3/00 - H04B11/00
    • H04B13/02—Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy
    • 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
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • 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
    • H04L25/03878—Line equalisers; line build-out devices

Definitions

  • the present application relates to the technical field of underwater acoustic communication, and in particular to a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code.
  • Polar codes constructed by related methods may not achieve sufficient performance in underwater acoustic communications due to the great differences between underwater acoustic channels and B-DMC channels, Gaussian channels, etc. Therefore, it is of great significance to construct Polar codes with excellent performance according to the characteristics of underwater acoustic channels and in combination with specific communication methods.
  • the technical problem to be solved by the present application is that, in view of the above-mentioned defects of the related art, a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code is provided, aiming to solve the problem that the Polar code constructed in the related art may not obtain sufficient performance in underwater acoustic communication.
  • an embodiment of the present application provides a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code, wherein the system includes:
  • a transmitting end device is used to perform polarization code encoding and modulation processing on the initial sequence to obtain an OFDM signal, and transmit a sound wave containing the OFDM signal; wherein the polarization code is constructed based on an improved Gaussian approximation method;
  • the receiving end device is used to receive a sound wave containing noise in an underwater acoustic channel, and perform analog-to-digital conversion, hybrid channel estimation, equalization, demodulation and polarization code decoding on the sound wave containing noise to obtain a decoding sequence; wherein the polarization code decoder in the receiving end device is cascaded with the hybrid channel estimation module and the equalizer to form a loop iteration.
  • the transmitting end device includes:
  • a first polar code encoder is used to encode an initial sequence using a polar code constructed by an improved Gaussian approximation method to obtain a coded signal;
  • a first channel modulator used for performing QPSK modulation on the coded signal
  • OFDM modulator used for performing OFDM modulation on the QPSK modulated signal
  • a digital-to-analog converter used to convert digital signals into analog signals
  • the transmitting transducer is used to transmit sound waves in the underwater acoustic channel.
  • the receiving end device includes:
  • a receiving transducer used for receiving sound waves in an underwater acoustic channel
  • Analog-to-digital converter used to convert analog signals into digital signals
  • a hybrid channel estimation module used to perform channel estimation by fusing a channel estimation method based on a pilot signal with a channel estimation method processed between blocks; wherein the channel estimation method processed between blocks is to perform decoding of a current OFDM block based on a channel estimation result of a previous OFDM block;
  • a channel equalizer used to compensate for the characteristics of the channel
  • An OFDM demodulator used for performing OFDM demodulation on the signal output by the channel equalizer
  • a channel demodulator used for performing QPSK demodulation on the signal demodulated by the OFDM demodulator
  • a polar code decoder used for decoding the signal output by the channel demodulator
  • a second polar code encoder configured to re-encode the signal decoded by the polar code decoder
  • a second channel modulator used for performing QPSK modulation on the signal encoded by the polar code encoder
  • the channel estimation module of the inter-block processing is used to decode the current OFDM block according to the channel estimation result of the previous OFDM block.
  • an embodiment of the present application further provides a signal processing method of a decoding cascade iterative underwater acoustic communication system based on a Gaussian approximation improved polarization code, wherein encoding an initial sequence using a polarization code constructed using a Gaussian approximation improved method includes:
  • a polar code is constructed based on the channel of Gaussian approximation criterion, and the initial sequence is encoded.
  • simulating a channel of an OFDM underwater acoustic system to determine that the channel has a channel Gaussian approximation criterion includes:
  • the underwater acoustic channel of the OFDM underwater acoustic system is simulated to determine that each subcarrier contains complex Gaussian random noise;
  • the noise variance of each subcarrier is summed and averaged to obtain the noise variance of the channel;
  • the channel According to the noise variance of the channel, it is determined that the channel has a channel Gaussian approximation criterion.
  • determining, according to the noise variance, that the channel has a channel Gaussian approximation criterion includes:
  • the channel Based on the noise variance and the estimated channel transfer function of each subchannel, it is determined that the channel has a channel Gaussian approximation criterion.
  • the channel includes a plurality of sub-channels; and the channel constructing a polar code based on a Gaussian approximation criterion and encoding an initial sequence includes:
  • the initial sequence is encoded according to the set of information bits and the generator matrix.
  • the performing channel estimation after fusing the channel estimation method based on the pilot signal with the channel estimation method based on the inter-block processing includes:
  • a first channel transfer function corresponding to a current OFDM symbol and a second channel transfer function corresponding to a previous OFDM symbol are merged to obtain a mixed channel transfer function.
  • obtaining a second channel transfer function corresponding to a previous OFDM symbol according to a decoded signal corresponding to a previous OFDM symbol includes:
  • the decoded signal corresponding to the previous OFDM symbol is polarization re-encoded and channel modulated to obtain a modulated signal;
  • the channel is estimated according to the modulated signal and the preprocessed signal to obtain a second channel transfer function.
  • performing polar code encoding and modulation processing on the initial sequence includes:
  • the initial sequence after polar code encoding and modulation processing is subjected to symbol mapping, serial-to-parallel conversion, subcarrier allocation, pilot insertion, inverse fast Fourier transform, cyclic prefix addition processing and parallel-to-serial conversion.
  • performing analog-to-digital conversion, hybrid channel estimation, equalization, demodulation, and polar code decoding on a sound wave containing noise includes:
  • the sound wave containing noise is subjected to analog-to-digital conversion, serial-to-parallel conversion, cyclic prefix removal, fast Fourier transform, hybrid channel estimation, equalization, pilot removal, parallel-to-serial conversion, demodulation and polarization code decoding to obtain a decoding sequence.
  • an embodiment of the present application further provides an intelligent terminal, comprising a memory and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by one or more processors, wherein the one or more programs include a signal processing method for executing a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code as described in any one of the above.
  • an embodiment of the present application also provides a non-temporary computer-readable storage medium.
  • the instructions in the storage medium are executed by a processor of an electronic device, the electronic device is enabled to execute a signal processing method for a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code as described in any one of the above.
  • the system of the embodiment of the present application includes: a transmitting end device, which is used to perform polarization code encoding and modulation processing on the initial sequence to obtain an OFDM signal, and transmit a sound wave containing the OFDM signal; wherein the polarization code is constructed based on the Gaussian approximation improvement method; a receiving end device, which is used to receive a sound wave containing noise in an underwater acoustic channel, and perform analog-to-digital conversion, hybrid channel estimation, equalization, demodulation and polarization code decoding on the sound wave containing noise to obtain a decoded sequence; wherein the polarization code decoder in the receiving end device is cascaded with the hybrid channel estimation module and the equalizer to form a cyclic iteration.
  • the coding technology of constructing polarization code based on the Gaussian approximation improvement method at the transmitting end in the embodiment of the present application can form different transmission coding schemes according to the characteristics of the underwater acoustic channel, so that the entire communication system has environmental adaptability under different channel conditions, and hybrid channel estimation is used at the receiving end to improve the accuracy of channel estimation, and the hybrid channel estimation module, the equalizer and the polarization code decoder are cascaded to form a cyclic iteration operation to improve the performance of the entire communication system.
  • FIG1 is a schematic diagram of a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polar code provided in an embodiment of the present application;
  • FIG2 is a diagram of a transmission sequence structure provided in an embodiment of the present application.
  • FIG3 is a graph showing the variation of polarization code error rate with signal-to-noise ratio based on the Gaussian approximation construction method under different code lengths in a time-varying channel provided by an embodiment of the present application;
  • FIG4 is a flowchart of processing an nth OFDM symbol by an inter-block iterative receiver provided in an embodiment of the present application
  • FIG5 is a block diagram of the internal structure of the smart terminal provided in an embodiment of the present application.
  • the present application discloses a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code.
  • the present application is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
  • the Gaussian approximation construction method of Polar code evolved from the density evolution method.
  • the density evolution method needs to integrate and iterate the channel error probability to construct Polar code, so its computational complexity is relatively high.
  • the Gaussian approximation method directly calculates the reliability index of each sub-channel using a mathematical formula by introducing the Gaussian approximation criterion, and the number of loop iterations is greatly reduced. Therefore, its computational complexity is much lower than that of the density evolution method.
  • the existing Gaussian approximation method is mainly applicable to Gaussian channels and needs to be improved or expanded before it can be applied to shallow water acoustic channels. In addition, the performance of existing underwater acoustic communication systems is poor.
  • this embodiment provides a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code.
  • the coding technology based on Gaussian approximation improved method to construct polarization code at the transmitting end can form different transmission coding schemes according to the characteristics of the underwater acoustic channel, so that the entire communication system has environmental adaptability under different channel conditions.
  • Hybrid channel estimation is used at the receiving end to improve the accuracy of channel estimation.
  • the hybrid channel estimation module, the equalizer and the polarization code decoder are cascaded to form a cyclic iterative operation to improve the performance of the entire communication system.
  • the specific system includes: a transmitting end device, which is used to perform polarization code encoding and modulation processing on the initial sequence to obtain an OFDM signal, and transmit a sound wave containing the OFDM signal; wherein the polarization code is constructed based on the Gaussian approximation improved method; a receiving end device, which is used to receive a sound wave containing noise in an underwater acoustic channel, and perform analog-to-digital conversion, hybrid channel estimation, equalization, demodulation and polarization code decoding on the sound wave containing noise to obtain a decoding sequence; wherein the polarization code decoder in the receiving end device is cascaded with the hybrid channel estimation module and the equalizer to form a cyclic iteration.
  • an embodiment of the present application provides a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code, the system comprising: a transmitting end device, used to perform polarization code encoding and modulation processing on an initial sequence to obtain an OFDM signal, and transmit a sound wave containing the OFDM signal; wherein the polarization code is constructed based on the Gaussian approximation improvement method; a receiving end device, used to receive a sound wave containing noise in an underwater acoustic channel, and perform analog-to-digital conversion, hybrid channel estimation, equalization, demodulation and polarization code decoding on the sound wave containing noise to obtain a decoded sequence; wherein the polarization in the receiving end device
  • the code decoder is cascaded with the hybrid channel estimation module and the equalizer to form a loop iteration.
  • the system uses the Gaussian approximation improvement method to construct polarization code (Polar code) in the transmitting device, so that the initial sequence can be better adapted to the underwater acoustic communication system after being encoded with the polarization code constructed by the Gaussian approximation improvement method, so that the information can be transmitted in a channel with a channel capacity close to 1, thereby improving the stability of signal transmission in the underwater acoustic communication system.
  • the initial sequence is polarization-coded and then channel modulated and OFDM-modulated to obtain an OFDM signal.
  • the principle of OFDM is to convert the binary data stream into a plurality of subchannels with relatively low transmission rates for transmission through serial-to-parallel conversion.
  • the transmitting device transmits processed sound waves containing OFDM signals.
  • the traditional receiving device adopts pilot-based channel estimation, and the channel estimation accuracy is low.
  • the system adopts hybrid channel estimation in the receiving device, which is an improvement on the existing pilot-based channel estimation and can achieve more accurate channel estimation.
  • the polarization code decoder, hybrid channel estimation module, and equalizer are cascaded and iterated in the receiving device, and the sequence obtained by the receiving end after decoding is used for the channel estimation of the next OFDM symbol, which effectively realizes the application of polarization code in complex underwater acoustic channels and improves the performance of the entire communication system.
  • the analog-to-digital conversion, equalization, and demodulation in the receiving device all use related technologies, and polarization code decoding is the inverse process of polarization code encoding.
  • the transmitting end device includes: a first polarization code encoder, used to encode an initial sequence using a polarization code constructed by an improved Gaussian approximation method to obtain a coded signal; a first channel modulator, used to perform QPSK modulation on the coded signal; an OFDM modulator, used to perform OFDM modulation on the QPSK modulated signal; a digital-to-analog converter, used to convert a digital signal into an analog signal; and a transmitting transducer, used to transmit sound waves in an underwater acoustic channel.
  • the transmitting end device includes a first polarization code encoder, a first channel modulator, an OFDM modulator, a digital-to-analog converter, and a transmitting transducer.
  • the function of the first polarization code encoder is to encode the initial sequence using the polarization code constructed by the Gaussian approximation improvement method to obtain a coded signal.
  • the polarization code encoding here is a channel coding. Selecting a good channel to transmit information is the key to Polar code encoding.
  • Polar code construction is a coding method that can achieve symmetric channel capacity.
  • the modulation method adopted by the first channel modulator includes but is not limited to BPSK, QPSK, QAM, 16PSK and other modulation methods.
  • the modulation method adopted by the first channel modulator is QPSK modulation to modulate the coded signal.
  • the OFDM modulator is mainly used to perform OFDM modulation on the QPSK modulated signal so that the signal is transmitted in N mutually orthogonal carriers.
  • the transmitting sequence at this time is shown in Figure 2. Since the signals output by the previous processing are all digital signals, digital signals cannot be transmitted in an underwater acoustic channel environment, so they need to be converted into analog signals through a digital-to-analog converter, and finally the sound waves are transmitted through the transmitting transducer.
  • the receiving end device includes: a receiving transducer for receiving sound waves in an underwater acoustic channel; an analog-to-digital converter for converting analog signals into digital signals; a hybrid channel estimation module for performing channel estimation after fusing a channel estimation method based on a pilot signal with a channel estimation method for inter-block processing; wherein the channel estimation method for inter-block processing is to decode the current OFDM block according to the channel estimation result of the previous OFDM block; and a channel equalizer for decoding the OFDM block.
  • the invention relates to a method for compensating for the characteristics of a channel; an OFDM demodulator, used to perform OFDM demodulation on a signal output by a channel equalizer; a channel demodulator, used to perform QPSK demodulation on a signal after OFDM demodulation; a polarization code decoder, used to decode a signal output by the channel demodulator; a second polarization code encoder, used to re-encode a signal decoded by the polarization code decoder; a second channel modulator, used to perform QPSK modulation on a signal encoded by the polarization code encoder; and a channel estimation module for inter-block processing, used to decode a current OFDM block according to a channel estimation result of a previous OFDM block.
  • the receiving end device includes a receiving transducer, an analog-to-digital converter, a hybrid channel estimation module, a channel equalizer, an OFDM demodulator, a channel demodulator, a polarization code decoder, a second polarization code encoder, a second channel modulator and a channel estimation module for inter-block processing.
  • the receiving transducer receives the sound wave containing noise in the underwater acoustic channel, it is converted into a digital signal through the analog-to-digital converter.
  • a hybrid channel estimation module is used to merge the channel estimation method based on the pilot signal with the channel estimation method for inter-block processing.
  • the channel estimation method for inter-block processing is to decode the current OFDM block according to the channel estimation result of the previous OFDM block, this means that the polarization code decoding of the current OFDM block is cascaded and iterated with the polarization code decoding of the previous OFDM block, thereby improving the performance of the underwater acoustic OFDM communication system.
  • the channel characteristics will be compensated by the channel equalizer, and then the channel demodulation will be performed by the channel demodulator according to the reverse processing process of the transmitting end.
  • the demodulation method also includes but is not limited to BPSK, QPSK, QAM, 16PSK and other demodulation methods.
  • QPSK demodulation is performed, and then demodulation is performed by the OFDM demodulator and decoding is performed by the polarization code decoder.
  • the system adds a second polarization code encoder and a second channel modulator to the receiving end device.
  • the second polarization code encoder is constructed using the improved polarization code construction method based on the Gaussian approximation criterion in the embodiment of the present application, and the polarization code encoder in the related art can be used.
  • the signal decoded by the polar code decoder in the receiving end device is re-encoded by a second polar code encoder, and then QPSK modulation is performed by a second channel modulator.
  • the QPSK modulated signal is input into a channel estimation module for inter-block processing.
  • the channel estimation module for inter-block processing performs channel estimation according to the QPSK modulated signal and the preprocessed signal to obtain a second channel transfer function. Assuming that the second channel transfer function is regarded as a channel estimation result of a previous OFDM block, the second channel transfer function can be used for decoding the current OFDM block.
  • This application proposes an improved Gaussian approximation method to construct polar codes.
  • this application makes full use of the characteristics of the underwater acoustic channel and improves the polar code construction method.
  • the channel estimation method is improved, and the improved channel estimation method facilitates further integration with the polar code decoder.
  • the improved channel estimation method is cascaded and iterated with the polarization code decoder to improve the performance of the underwater acoustic OFDM communication system.
  • This embodiment provides a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code
  • the signal processing method can be applied to intelligent terminals of underwater acoustic communication.
  • encoding an initial sequence using a polarization code constructed using an improved Gaussian approximation method includes the following steps: simulating a channel of an OFDM underwater acoustic system to determine that the channel has a channel Gaussian approximation criterion; wherein the Gaussian approximation criterion is used to characterize that the channel has a Gaussian approximation characteristic; constructing a polarization code based on the channel of the Gaussian approximation criterion, and encoding the initial sequence.
  • the channel of the OFDM underwater acoustic system is simulated. Since the subcarriers in the OFDM underwater acoustic system are mutually orthogonal, the multipath interference of the underwater acoustic channel can be eliminated for each subcarrier. For each subcarrier, its noise can be approximated as complex Gaussian random noise. After summing and averaging all subcarriers, the noise variance is also complex Gaussian random noise. Based on this, it can be determined that the channel has the channel Gaussian approximation criterion. Then, the polarization code is constructed according to the channel of the Gaussian approximation criterion, and the initial sequence is encoded. In this way, the system can realize stable transmission of information under different channel conditions.
  • simulating the channel of an OFDM underwater acoustic system and determining that the channel has a channel Gaussian approximation criterion includes the following steps: simulating the underwater acoustic channel of the OFDM underwater acoustic system and determining that each subcarrier contains complex Gaussian random noise; obtaining the noise variance of each subcarrier based on the complex Gaussian random noise; summing and averaging the noise variances of all subcarriers to obtain the noise variance of the channel; and determining that the channel has a channel Gaussian approximation criterion based on the noise variance of the channel and the transmission function of the underwater acoustic channel.
  • the process of simulating the underwater acoustic channel of the OFDM underwater acoustic system is as follows: after underwater acoustic OFDM modulation and demodulation, the underwater acoustic channel is converted from a frequency selective fading broadband channel to a set of flat fading narrowband channels W k (y
  • the second term in the above formula is It can be approximated as complex Gaussian random noise, that is, each subcarrier contains complex Gaussian random noise.
  • the noise mean of each subcarrier is 0, and the noise variance of each subcarrier is Sum and average all subcarriers to get the channel noise variance It can be expressed as:
  • determining that the channel has a channel Gaussian approximation criterion based on the noise variance includes the following steps: sending a pilot signal, and performing channel estimation on the pilot signal at a receiving end device to obtain an estimated channel transfer function for each subchannel; and determining that the channel has a channel Gaussian approximation criterion based on the noise variance and the estimated channel transfer function for each subchannel.
  • the sequence of the pilot signal can be in the form of LFM, HFM, CW and any combination thereof.
  • the channel state information H(f k ) is usually unknown.
  • the estimated channel transfer function of each subchannel can be obtained by sending a pilot signal and performing channel estimation on the pilot signal at the receiving end device.
  • the channel estimation process is a prior art and will not be described in detail here. and the estimated channel transfer function for each subchannel Formula (1) and formula (2) can be updated as follows:
  • Rk is composed of the channel state information estimate and the transmission code sequence
  • the calculation can be expressed as:
  • the channel includes a plurality of subchannels; constructing a polar code based on the channel of the Gaussian approximation criterion and encoding the initial sequence includes: calculating a plurality of log-likelihood ratios of each first-order subchannel of the Gaussian approximation criterion; recursively calculating a mean of a plurality of log-likelihood ratios of each N-order subchannel; sorting the means of all subchannels in descending order; taking a plurality of subchannels with the highest sorting order as an information bit set; and encoding the initial sequence according to the information bit set.
  • the channel of the Gaussian approximation criterion contains multiple sub-channels.
  • a number of log-likelihood ratios of the first-order subchannels of the Gaussian approximation criterion are obtained, and then the mean values E i of the log-likelihood ratios LLR N (i) of the N-order subchannels are recursively calculated according to the iterative formula.
  • the iterative calculation formula for the mean value of the polarization subchannel LLR of the improved Gaussian approximation Polar code construction method can be derived according to the Gaussian approximation criterion of the underwater acoustic channel.
  • the iterative formulas for the odd-numbered terms and the even-numbered terms are respectively:
  • the iterative calculation of the LLR mean of the high-order polarization subchannel starts with the first-order LLR.
  • the first-order LLR is calculated by the channel
  • encoding the initial sequence according to the information bit set includes the following steps: obtaining a generator matrix; encoding the initial sequence according to the information bit set and the generator matrix.
  • the generator matrix of the polar code can be obtained as G N .
  • the initial sequence Multiplying by the generator matrix G N we get To complete the encoding of the initial sequence.
  • the information transmission channel is taken as an information bit set, represented by A.
  • A is a subset of the number of matrix rows in the generator matrix G N
  • G N (A) is the matrix composed of the rows corresponding to the set A in the generator matrix G N
  • Ac is the complement of A.
  • the polar code encoding is expressed as Where N is the code length, K is the number of elements in A, and A is the information bit. is the frozen bit.
  • N is the code length
  • K is the number of elements in A
  • A is the information bit. is the frozen bit.
  • the bit error rate of Polar codes with different code lengths varies with the signal-to-noise ratio.
  • the bit error rate value of code length 2048 is relatively the highest, followed by the bit error rate values of code length 1024 and code length 512.
  • bit error rate curve of code length 2048 begins to decay first and the decay amplitude is the largest, followed by the bit error rate curves of code length 1024 and code length 512.
  • the bit error rate of code length 2048 has a gain of about 0.7dB relative to the bit error rate of code length 1024, and the bit error rate of code length 1024 has a gain of about 0.5dB relative to the bit error rate of code length 512.
  • the polar code decoding and the polar code encoding are both based on the same polarization construction result, that is, an information bit set.
  • decoding is the inverse process of encoding.
  • both polar code decoding and polar code encoding are information bit sets constructed by applying Gaussian approximation, that is, the subchannels corresponding to the top K mean values E i are information transmission channels, and are channels whose channel capacity approaches 1.
  • u 1 N uses the water acoustic subchannels (information transmission channels) corresponding to the top K mean values E i to obtain the coded sequence x 1 N .
  • the coded sequence x 1 N is passed through the OFDM water acoustic communication system to obtain the received sequence y 1 N .
  • the Polar coding and decoding are combined with the water acoustic channel to form a virtual subchannel, that is,
  • the channel estimation result of the LS method is affected by channel noise under low signal-to-noise ratio conditions, and the channel change information cannot be obtained in time by using only the training sequence estimation in the time-varying channel.
  • a method is adopted to use the received information on all subcarriers of the OFDM receiving end for channel estimation and combine it with the LS estimation result of the pilot sequence, which can supplement the LS method. Channel variation information in the estimation result.
  • the present application combines the decoding of polarization codes with OFDM channel estimation and adopts the channel estimation method of inter-block processing, that is, the channel estimation result of the previous OFDM block is used for the decoding of the current OFDM block.
  • the channel estimation method of inter-block processing is combined with the channel estimation method based on pilot signals, and an iterative receiver is set up with the aid of channel decoding estimation values, thereby improving the accuracy of channel estimation and reducing the use of pilot subcarrier systems.
  • the channel estimation after fusing the channel estimation method based on the pilot signal with the channel estimation method of inter-block processing includes the following steps: converting the received signal from the time domain to the frequency domain to obtain a preprocessed signal; estimating the channel based on the pilot signal in the preprocessed signal to obtain a first channel transfer function corresponding to the current OFDM symbol; obtaining a decoded signal corresponding to the previous OFDM symbol; obtaining a second channel transfer function corresponding to the previous OFDM symbol based on the decoded signal corresponding to the previous OFDM symbol; fusing the first channel transfer function corresponding to the current OFDM symbol with the second channel transfer function corresponding to the previous OFDM symbol to obtain a mixed channel transfer function.
  • the received signal is converted from the time domain to the frequency domain by FFT to obtain a preprocessed signal, which includes a pilot signal.
  • channel estimation is performed based on the pilot signal to obtain a first channel transfer function
  • only Channel equalization and decoding are performed, assuming that the decoding output value of the first OFDM symbol of the group is accurate, and a decoded signal corresponding to the OFDM symbol is obtained;
  • the decoded signal corresponding to the OFDM symbol is subjected to polarization code recoding and channel modulation to obtain a modulated signal; then the channel is estimated according to the modulated signal and the preprocessed signal to obtain a second channel transfer function, that is, in combination with the corresponding sequence of the preprocessing output, the corresponding channel estimation value (second channel transfer function) can be obtained as follows:
  • y m (n-1) represents the n-1th group of OFDM sequences in the mth frame received signal, It represents the output sequence of its corresponding decoded output sequence after re-encoding and QPSK modulation.
  • the iterative decoding estimate that is, the second channel transfer function
  • the first channel transfer function Input hybrid estimation module used for channel estimation of nth group OFDM sequence, for the first channel transfer function and the second channel transfer function Perform weighted averaging and define the weight coefficient ⁇ (0,1), then the output of the mixed channel estimation (i.e., the mixed channel transfer function) is:
  • the steps of performing polar code encoding and modulation processing on the initial sequence include: performing symbol mapping, serial-to-parallel conversion, subcarrier allocation, pilot insertion, inverse fast Fourier transform, cyclic prefix addition processing, and parallel-to-serial conversion on the initial sequence after the polar code encoding and modulation processing.
  • a cyclic prefix CP is inserted before each group of OFDM symbols as a guard interval (GI), and the time length Tcp of the CP should be greater than the maximum multipath delay Tch of the underwater acoustic channel.
  • GI guard interval
  • performing analog-to-digital conversion, hybrid channel estimation, equalization, demodulation, and polarization code decoding on a sound wave containing noise includes the following steps: performing analog-to-digital conversion, serial-to-parallel conversion, cyclic prefix removal, fast Fourier transform, hybrid channel estimation, equalization, pilot removal, parallel-to-serial conversion, demodulation, and polarization code decoding on the sound wave containing noise to obtain a decoding sequence.
  • the above processing is prior art and will not be repeated here.
  • the present application also provides an intelligent terminal, whose principle block diagram can be shown in Figure 5.
  • the intelligent terminal includes a processor, a memory, a network interface, a display screen, and a temperature sensor connected through a system bus.
  • the processor of the intelligent terminal is used to provide computing and control capabilities.
  • the memory of the intelligent terminal includes a non-volatile storage medium and an internal memory.
  • the non-volatile storage medium stores an operating system and a computer program.
  • the internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium.
  • the network interface of the intelligent terminal is used to communicate with an external terminal through a network connection.
  • the display screen of the intelligent terminal can be a liquid crystal display screen or an electronic ink display screen, and the temperature sensor of the intelligent terminal is pre-set inside the intelligent terminal to detect the operating temperature of the internal device.
  • FIG5 is merely a block diagram of a partial structure related to the scheme of the present application, and does not constitute a limitation on the smart terminal to which the scheme of the present application is applied.
  • a specific smart terminal may include more or fewer components than shown in the figure, or combine certain components, or have a different arrangement of components.
  • a smart terminal comprising a memory and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by one or more processors, wherein the one or more programs include instructions for performing the following operations:
  • the polar code constructed by the Gaussian approximation improvement method is used to encode the initial sequence, including:
  • a polar code is constructed based on the channel of Gaussian approximation criterion, and the initial sequence is encoded.
  • the channel of the OFDM underwater acoustic system is simulated to determine the The channel has a channel Gaussian approximation criterion including:
  • the underwater acoustic channel of the OFDM underwater acoustic system is simulated to determine that each subcarrier contains complex Gaussian random noise;
  • the noise variance of each subcarrier is summed and averaged to obtain the noise variance of the channel;
  • the channel According to the noise variance of the channel, it is determined that the channel has a channel Gaussian approximation criterion.
  • determining, according to the noise variance, that the channel has a channel Gaussian approximation criterion includes:
  • the channel Based on the noise variance and the estimated channel transfer function of each subchannel, it is determined that the channel has a channel Gaussian approximation criterion.
  • the channel includes a plurality of sub-channels; and the channel constructing a polar code based on a Gaussian approximation criterion and encoding an initial sequence includes:
  • the initial sequence is encoded according to the set of information bits and the generator matrix.
  • the performing channel estimation after fusing the channel estimation method based on the pilot signal with the channel estimation method based on the inter-block processing includes:
  • a first channel transfer function corresponding to a current OFDM symbol and a second channel transfer function corresponding to a previous OFDM symbol are merged to obtain a mixed channel transfer function.
  • obtaining a second channel transfer function corresponding to a previous OFDM symbol according to a decoded signal corresponding to a previous OFDM symbol includes:
  • the decoded signal corresponding to the previous OFDM symbol is polarization re-encoded and channel modulated to obtain a modulated signal;
  • the channel is estimated according to the modulated signal and the preprocessed signal to obtain a second channel transfer function.
  • performing polar code encoding and modulation processing on the initial sequence includes:
  • the initial sequence after polar code encoding and modulation is symbol mapped, serial-to-parallel converted, Subcarrier allocation, pilot insertion, inverse fast Fourier transform, cyclic prefix addition and parallel-to-serial conversion.
  • performing analog-to-digital conversion, hybrid channel estimation, equalization, demodulation, and polar code decoding on a sound wave containing noise includes:
  • the sound wave containing noise is subjected to analog-to-digital conversion, serial-to-parallel conversion, cyclic prefix removal, fast Fourier transform, hybrid channel estimation, equalization, pilot removal, parallel-to-serial conversion, demodulation and polarization code decoding to obtain a decoding sequence.
  • Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory.
  • Volatile memory can include random access memory (RAM) or external cache memory.
  • RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
  • the present application discloses a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code, the system comprising: a transmitting end device, used to perform polarization code encoding and modulation processing on an initial sequence to obtain an OFDM signal, and transmit a sound wave containing the OFDM signal; a receiving end device, used to receive a sound wave containing noise in an underwater acoustic channel, and perform analog-to-digital conversion, hybrid channel estimation, equalization, demodulation and polarization code decoding on the sound wave containing noise to obtain a decoding sequence; the embodiment of the present application adopts a coding technology based on Gaussian approximation improvement method to construct polarization code at the transmitting end, which can form different transmission coding schemes according to the characteristics of the underwater acoustic channel, so that the entire communication system has environmental adaptability under different channel conditions, and adopts hybrid channel estimation at the receiving end to improve the accuracy of channel estimation, and cascades
  • the present application discloses a signal processing method for a decoding cascade iterative underwater acoustic communication system based on Gaussian approximation improved polarization code. It should be understood that the application of the present application is not limited to the above examples. For ordinary technicians in this field, it can be improved or transformed according to the above description, and all these improvements and transformations should fall within the scope of protection of the claims attached to the present application.

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Abstract

本申请公开了一种基于高斯近似改进极化码的译码级联迭代水声通信系统，系统包括：发射端装置，用于将初始序列进行极化码编码和调制处理，得到OFDM信号，并发射包含OFDM信号的声波；接收端装置，用于在水声信道接收包含噪声的声波，并将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码，得到译码序列。

Description

基于高斯近似改进极化码的译码级联迭代水声通信系统
相关申请
本申请要求于2022年9月28日申请的、申请号为202211186861.4的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及水声通信技术领域，尤其涉及的是基于高斯近似改进极化码的译码级联迭代水声通信系统。
背景技术
虽然水声通信中Polar码的研究取得一定的研究进展，但由于水声信道与B-DMC信道，高斯信道等有很大差别，相关方法构造的Polar码在水声通信中可能无法获得足够的性能，因此，根据水声信道特点，结合具体的通信方式构造性能优异的Polar码有重要意义。
因此，相关技术还有待改进和发展。
发明内容
本申请要解决的技术问题在于，针对相关技术的上述缺陷，提供一种基于高斯近似改进极化码的译码级联迭代水声通信系统，旨在解决相关技术中构造的Polar码在水声通信中可能无法获得足够的性能的问题。
本申请解决问题所采用的技术方案如下：
第一方面，本申请实施例提供一种基于高斯近似改进极化码的译码级联迭代水声通信系统，其中，所述系统包括：
发射端装置，用于将初始序列进行极化码编码和调制处理，得到OFDM信号，并发射包含OFDM信号的声波；其中，所述极化码基于高斯近似改进法构造；
接收端装置，用于在水声信道接收包含噪声的声波，并将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码，得到译码序列；其中，所述接收端装置中的极化码译码器与混合信道估计模块、均衡器级联，形成循环迭代。
在一种实现方式中，所述发射端装置包括：
第一极化码编码器，用于采用高斯近似改进法构造的极化码对初始序列进行编码，得到编码信号；
第一信道调制器，用于对所述编码信号进行QPSK调制；
OFDM调制器，用于对QPSK调制后的信号进行OFDM调制；
数模转换器，用于将数字信号转换成模拟信号；
发射换能器，用于在水声信道发射声波。
在一种实现方式中，所述接收端装置包括：
接收换能器，用于在水声信道接收声波；
模数转换器，用于将模拟信号转换成数字信号；
混合信道估计模块，用于将基于导频信号的信道估计方式与块间处理的信道估计方式融合后进行信道估计；其中，所述块间处理的信道估计方式为根据前一个OFDM块的信道估计结果来进行当前OFDM块的译码；
信道均衡器，用于对信道的特性进行补偿；
OFDM解调器，用于对信道均衡器输出的信号进行OFDM解调；
信道解调器，用于对OFDM解调器解调后信号进行QPSK解调；
极化码译码器，用于对信道解调器输出的信号进行译码；
第二极化码编码器，用于将所述极化码译码器译码后的信号进行重编码；
第二信道调制器，用于将所述极化码编码器编码后的信号进行QPSK调制；
块间处理的信道估计模块，用于根据前一个OFDM块的信道估计结果来进行当前OFDM块的译码。
第二方面，本申请实施例还提供一种基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法，其中，采用高斯近似改进法构造的极化码对初始序列进行编码包括：
对OFDM水声系统的信道进行仿真，确定所述信道具有信道高斯近似准则；其中，所述高斯近似准则用于表征信道具有高斯近似的特性；
基于高斯近似准则的信道构造极化码，并对初始序列进行编码。
在一种实现方式中，所述对OFDM水声系统的信道进行仿真，确定所述信道具有信道高斯近似准则包括：
对OFDM水声系统的水声信道进行仿真，确定每个子载波包含复高斯随机噪声；
根据所述复高斯随机噪声，得到每个子载波的噪声方差；
将所有每个子载波的噪声方差进行求和平均，得到信道的噪声方差；
根据信道的噪声方差，确定所述信道具有信道高斯近似准则。
在一种实现方式中，所述根据所述噪声方差，确定所述信道具有信道高斯近似准则包括：
发送导频信号，并在接收端装置对所述导频信号进行信道估计，得到每个子信道的预估信道传递函数；
基于所述噪声方差和每个子信道的预估信道传递函数，确定所述信道具有信道高斯近似准则。
在一种实现方式中，所述信道包括若干子信道；所述基于高斯近似准则的信道构造极化码，并对初始序列进行编码包括：
计算高斯近似准则的每个一阶子信道的若干对数似然比；
递推计算每个N阶子信道的若干对数似然比的均值；
将所有子信道的均值按照从大到小的顺序进行排序；
将排序靠前的若干子信道作为信息位集合；
获取生成矩阵；
根据所述信息位的集合和所述生成矩阵，对所述初始序列进行编码。
在一种实现方式中，所述将基于导频信号的信道估计方式与块间处理的信道估计方式融合后进行信道估计包括：
将接收信号从时域转换到频域，得到预处理信号；
基于所述预处理信号中的导频信号对信道进行估计，得到当前OFDM符号对应的第一信道传递函数；
获取前一个OFDM符号对应的译码信号；
根据前一个OFDM符号对应的译码信号，得到前一个OFDM符号对应的第二信道传递函数；
将当前OFDM符号对应的第一信道传递函数和前一个OFDM符号对应的第二信道传递函数进行融合，得到混合信道传递函数。
在一种实现方式中，所述根据前一个OFDM符号对应的译码信号，得到前一个OFDM符号对应的第二信道传递函数包括：
将前一个OFDM符号对应的译码信号进行极化重编码和信道调制，得到调制信号；
根据所述调制信号和所述预处理信号对信道进行估计，得到第二信道传递函数。
在一种实现方式中，将初始序列进行极化码编码和调制处理之后包括：
将进行极化码编码和调制处理后的初始序列进行符号映射、串并转换、子载波分配、导频插入、快速傅里叶逆变换、循环前缀的添加处理和并串转换。
在一种实现方式中，将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码包括：
将包含噪声的声波进行模数转换、串并转换、循环前缀的移除处理、快速傅里叶变换、混合信道估计、均衡、导频的去除处理、并串转换、解调和极化码译码，得到译码序列。
第三方面，本申请实施例还提供一种智能终端，包括有存储器，以及一个或者一个以上的程序，其中一个或者一个以上程序存储于存储器中，且经配置以由一个或者一个以上处理器执行所述一个或者一个以上程序包含用于执行如上述任意一项所述的基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法。
第四方面，本申请实施例还提供一种非临时性计算机可读存储介质，当所述存储介质中的指令由电子设备的处理器执行时，使得电子设备能够执行如上述中任意一项所述的基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法。
本申请的有益效果：本申请实施例的系统包括：发射端装置，用于将初始序列进行极化码编码和调制处理，得到OFDM信号，并发射包含OFDM信号的声波；其中，所述极化码基于高斯近似改进法构造；接收端装置，用于在水声信道接收包含噪声的声波，并将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码，得到译码序列；其中，所述接收端装置中的极化码译码器与混合信道估计模块、均衡器级联，形成循环迭代。可见，本申请实施例中在发射端采用基于高斯近似改进法构造极化码的编码技术可根据水声信道特点，形成不同的传输编码方案，使得整个通信系统在不同信道条件下具有环境适应性，在接收端采用混合信道估计，提高信道估计准确性，将混合信道估计模块、均衡器与极化码译码器级联，构成循环迭代运算，提高整个通信系统的性能。
附图说明
为了更清楚地说明本申请实施例或相关技术中的技术方案，下面将对实施例或相关技术描述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申请中记载的一些实施例，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为本申请实施例提供的基于高斯近似改进极化码的译码级联迭代水声通信系统示意图；
图2为本申请实施例提供的发射序列结构图；
图3为本申请实施例提供的时变信道中，不同码长下基于高斯近似构造方法的极化码误码率随信噪比的变化图；
图4为本申请实施例提供的块间迭代接收机对第n个OFDM符号的处理流程图；
图5为本申请实施例提供的智能终端的内部结构原理框图。
具体实施方式
本申请公开了一种基于高斯近似改进极化码的译码级联迭代水声通信系统，为使本申请的目的、技术方案及效果更加清楚、明确，以下参照附图并举实施例对本申请进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本申请，并不用于限定本申请。
本技术领域技术人员可以理解，除非特意声明，这里使用的单数形式“一”、“一个”、“所述”和“该”也可包括复数形式。应该进一步理解的 是，本申请的说明书中使用的措辞“包括”是指存在所述特征、整数、步骤、操作、元件和/或组件，但是并不排除存在或添加一个或多个其他特征、整数、步骤、操作、元件、组件和/或它们的组。应该理解，当我们称元件被“连接”或“耦接”到另一元件时，它可以直接连接或耦接到其他元件，或者也可以存在中间元件。此外，这里使用的“连接”或“耦接”可以包括无线连接或无线耦接。这里使用的措辞“和/或”包括一个或更多个相关联的列出项的全部或任一单元和全部组合。
本技术领域技术人员可以理解，除非另外定义，这里使用的所有术语(包括技术术语和科学术语)，具有与本申请所属领域中的普通技术人员的一般理解相同的意义。还应该理解的是，诸如通用字典中定义的那些术语，应该被理解为具有与相关技术的上下文中的意义一致的意义，并且除非像这里一样被特定定义，否则不会用理想化或过于正式的含义来解释。
由于相关技术中，Polar码的高斯近似构造法由密度进化法演化而来。密度进化法构造Polar码需要对信道错误概率进行积分迭代，因此其计算复杂度较高，而高斯近似法通过引入高斯近似准则，直接用数学公式计算各子信道的可靠性指标，循环迭代次数得以大大减少，因此其计算复杂度与密度进化法相比下降了很多。现有的高斯近似法主要适用于高斯信道，需要进行改进或扩展，才能将其应用于浅海水声信道，且现有的水声通信系统的性能较差。
为了解决相关技术的问题，本实施例提供了基于高斯近似改进极化码的译码级联迭代水声通信系统，在发射端采用基于高斯近似改进法构造极化码的编码技术可根据水声信道特点，形成不同的传输编码方案，使得整个通信系统在不同信道条件下具有环境适应性，在接收端采用混合信道估计，提高信道估计准确性，将混合信道估计模块、均衡器与极化码译码器级联，构成循环迭代运算，提高整个通信系统的性能。具体系统包括：发射端装置，用于将初始序列进行极化码编码和调制处理，得到OFDM信号，并发射包含OFDM信号的声波；其中，所述极化码基于高斯近似改进法构造；接收端装置，用于在水声信道接收包含噪声的声波，并将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码，得到译码序列；其中，所述接收端装置中的极化码译码器与混合信道估计模块、均衡器级联，形成循环迭代。
示例性设备
如图1中所示，本申请实施例提供基于高斯近似改进极化码的译码级联迭代水声通信系统，该系统包括：发射端装置，用于将初始序列进行极化码编码和调制处理，得到OFDM信号，并发射包含OFDM信号的声波；其中，所述极化码基于高斯近似改进法构造；接收端装置，用于在水声信道接收包含噪声的声波，并将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码，得到译码序列；其中，所述接收端装置中的极化 码译码器与混合信道估计模块、均衡器级联，形成循环迭代。
具体地，本系统在发射端装置中采用高斯近似改进法构造极化码(Polar码)，这样初始序列经过高斯近似改进法构造极化码编码后，可以更好的适应水声通信系统，使得信息能在信道容量趋近于1的信道中传输，从而提高水声通信系统中信号传输的稳定性。在本实施例中，初始序列进行极化码编码后进行信道调制和OFDM调制，得到的是OFDM信号，OFDM的原理是将二进制的数据流通过串并转换，分配到传输速率相对较低的若干个子信道中进行传输。此外，由于是在水下进行通信，故发射端装置发射的是经过处理的包含OFDM信号的声波。传统的接收端装置采用基于导频的信道估计，信道估计准确性低，本系统在接收端装置采用混合信道估计，是对现有基于导频的信道估计进行改进，能够实现更为准确的信道估计。此外，在接收端装置中极化码译码器与混合信道估计模块、均衡器级联迭代，将接收端通过译码后得到的序列用于下一个OFDM符号的信道估计，有效的实现了极化码在复杂水声信道中的应用，提升了整个通信系统的性能。接收端装置中的模数转换、均衡、解调均采用的相关技术，极化码译码是极化码编码的逆过程。
在一种实现方式中，所述发射端装置包括：第一极化码编码器，用于采用高斯近似改进法构造的极化码对初始序列进行编码，得到编码信号；第一信道调制器，用于对所述编码信号进行QPSK调制；OFDM调制器，用于对QPSK调制后的信号进行OFDM调制；数模转换器，用于将数字信号转换成模拟信号；发射换能器，用于在水声信道发射声波。
具体地，发射端装置包括第一极化码编码器、第一信道调制器、OFDM调制器、数模转换器、发射换能器。第一极化码编码器的功能是采用高斯近似改进法构造的极化码对初始序列进行编码，得到编码信号。值得注意的是，此处的极化码编码是一种信道编码，选择一个好的信道来传输信息是Polar码编码的关键，Polar码构造的是一个能够达到对称信道容量的编码方法。第一信道调制器采用的调制方式包括但不限于BPSK、QPSK、QAM、16PSK等调制方式。在本实施例中，第一信道调制器采用的调制方式为QPSK调制方式对所述编码信号进行调制。OFDM调制器，主要用于对QPSK调制后的信号进行OFDM调制，使得信号在N路相互正交的载波中进行传输，此时的发射序列如图2所示。由于前面处理输出的信号都是数字信号，数字信号无法在水声信道环境中进行传输，故需要通过数模转换器转换成模拟信号，最后通过发射换能器发射声波。
在一种实现方式中，所述接收端装置包括：接收换能器，用于在水声信道接收声波；模数转换器，用于将模拟信号转换成数字信号；混合信道估计模块，用于将基于导频信号的信道估计方式与块间处理的信道估计方式融合后进行信道估计；其中，所述块间处理的信道估计方式为根据前一个OFDM块的信道估计结果来进行当前OFDM块的译码；信道均衡器，用于对 信道的特性进行补偿；OFDM解调器，用于对信道均衡器输出的信号进行OFDM解调；信道解调器，用于对OFDM解调后的信号进行QPSK解调；极化码译码器，用于对信道解调器输出的信号进行译码；第二极化码编码器，用于将所述极化码译码器译码后的信号进行重编码；第二信道调制器，用于将所述极化码编码器编码后的信号进行QPSK调制；块间处理的信道估计模块，用于根据前一个OFDM块的信道估计结果来进行当前OFDM块的译码。
具体地，接收端装置包括接收换能器、模数转换器、混合信道估计模块、信道均衡器、OFDM解调器、信道解调器、极化码译码器、第二极化码编码器、第二信道调制器和块间处理的信道估计模块。接收换能器接收了水声信道中包含噪声的声波后，通过模数转换器转换成数字信号。为了提高信道估计的准确性，采用混合信道估计模块，将基于导频信号的信道估计方式与块间处理的信道估计方式进行融合，由于块间处理的信道估计方式为根据前一个OFDM块的信道估计结果来进行当前OFDM块的译码，这样也就意味着，当前OFDM块的极化码译码与前一个OFDM块的极化码译码进行了级联迭代，实现了水声OFDM通信系统性能的提升。信号经过估计后会通过信道均衡器对信道的特性进行补偿，接着根据与发射端相逆的处理过程，会通过信道解调器进行信道解调，解调方式同样包括但不局限于BPSK、QPSK、QAM、16PSK等解调方式。在本实施例中，进行QPSK解调，然后通过OFDM解调器进行解调和极化码译码器译码。值得注意的是，与相关技术相比，本系统在接收端装置增加了第二极化码编码器和第二信道调制器，第二极化码编码器采用本申请实施例中的基于高斯近似准则改进的极化码构造方法进行构造，可以采用相关技术中的极化码编码器。通过第二极化码编码器将所述接收端装置中极化码译码器译码后的信号进行重编码，然后通过第二信道调制器进行QPSK调制,最后将QPSK调制后的信号输入到块间处理的信道估计模块，块间处理的信道估计模块根据QPSK调制后的信号和预处理信号进行信道估计，得到第二信道传递函数，假设将该第二信道传递函数看作前一个OFDM块的信道估计结果，那么这个第二信道传递函数可以用于对当前OFDM块的译码。
本申请的特点：
1.本申请提出了一种改进的高斯近似法构造极化码。在发射端，与以往极化码编码方式不同，本申请充分利用了水声信道特点，对极化码的构造方法进行了改进。
2.在接收端，改进信道估计方法，改进后的信道估计方法便于实现与极化码解码器的进一步结合。
3.在接收端，将改进的信道估计方法与极化码解码器进行级联迭代，实现了水声OFDM通信系统性能的提升。
示例性方法
本实施例提供基于高斯近似改进极化码的译码级联迭代水声通信系统 的信号处理方法，该方法可以应用于水声通信的智能终端。
在一种实现方式中，采用高斯近似改进法构造的极化码对初始序列进行编码包括如下步骤：对OFDM水声系统的信道进行仿真，确定所述信道具有信道高斯近似准则；其中，所述高斯近似准则用于表征信道具有高斯近似的特性；基于高斯近似准则的信道构造极化码，并对初始序列进行编码。
具体地，对OFDM水声系统的信道进行仿真，由于OFDM水声系统中各个子载波是相互正交的，故对于每个子载波而言可以消除水声信道的多径干扰，对于每个子载波而言，其噪声可以近似为复高斯随机噪声，对所有子载波进行求和平均后，噪声方差也是复高斯随机噪声，基于此，可以确定所述信道具有信道高斯近似准则。接着根据高斯近似准则的信道构造极化码，并对初始序列进行编码。这样，系统可以实现在不同的信道条件下进行信息的稳定传输。
在一种实现方式中，所述对OFDM水声系统的信道进行仿真，确定所述信道具有信道高斯近似准则包括如下步骤：对OFDM水声系统的水声信道进行仿真，确定每个子载波包含复高斯随机噪声；根据所述复高斯随机噪声，得到每个子载波的噪声方差；将所有每个子载波的噪声方差进行求和平均，得到信道的噪声方差；根据信道的噪声方差以及水声信道的传输函数，确定所述信道具有信道高斯近似准则。
具体地，对OFDM水声系统的水声信道进行仿真的过程如下：经水声OFDM调制和解调后，水声信道由频率选择性衰落宽带信道转换为一组平坦衰落的窄带信道Wk(y|x)，k∈SA。若各子载波的信道状态信息(Channel State Information,CSI)H(fk)已知，将其代入Y(fk)＝Y(f)|f＝fk＝H(fk)s[k]+N(fk)式(其中，Y(fk)是接收信号y(t)的傅里叶变换，s[k]为一帧OFDM传输块中第k(k＝0,1,…K-1)个子载波对应的发送符号，H(fk)为第k个子载波信道上的传递函数，N(fk)为第k个子载波对应的噪声谱)，得到发送序列的估计值为：
考虑信号的统计分布特性，则上式中的第二项可近似为复高斯随机噪声，也即每个子载波包含复高斯随机噪声。根据所述复高斯随机噪声，得到每个子载波的噪声均值为0，每个子载波的噪声方差为对所有的子载波进行求和平均，得到信道的噪声方差可表示为:
最后根据信道的噪声方差，确定所述信道具有信道高斯近似准则。相 应的，所述根据所述噪声方差，确定所述信道具有信道高斯近似准则包括如下步骤：发送导频信号，并在接收端装置对所述导频信号进行信道估计，得到每个子信道的预估信道传递函数；基于所述噪声方差和每个子信道的预估信道传递函数，确定所述信道具有信道高斯近似准则。
具体地，导频信号的序列可以为LFM,HFM,CW等信号及其任何组合等形式。在实际水声通信过程中，信道状态信息H(fk)通常不可知，可以采用发送导频信号，并在接收端装置对所述导频信号进行信道估计的方式，得到每个子信道的预估信道传递函数信道估计的过程为现有技术，在此不再赘述。接着基于所述噪声方差和每个子信道的预估信道传递函数公式(1)和公式(2)可以更新为：

由信道状态信息的估计值和信道噪声方差可推导出水声信道的高斯近似准则为：
D[Ls[k]]＝2RkE[Ls[k]]   (5)
上式Rk由信道状态信息估计值和传输编码序列计算，可表示为：
其中为编码序列的QPSK调制结果。
在一种实现方式中，所述信道包括若干子信道；所述基于高斯近似准则的信道构造极化码，并对初始序列进行编码包括：计算高斯近似准则的每个一阶子信道的若干对数似然比；递推计算每个N阶子信道的若干对数似然比的均值；将所有子信道的均值按照从大到小的顺序进行排序；将排序靠前的若干子信道作为信息位集合；根据所述信息位集合，对初始序列进行编码。
具体地，高斯近似准则的信道包含多个子信道，根据公式得到高斯近似准则的一阶子信道的若干对数似然比，再根据迭代公式递推计算N阶子信道的若干对数似然比LLRN (i)的均值Ei，在本实施例中，根据水声信道的高斯近似准则可推导出改进的高斯近似Polar码构造方法的极化子信道LLR均值迭代计算公式，奇数项和偶数项的迭代公式分别为：

对高阶极化子信道的LLR均值迭代计算由一阶LLR开始，一阶LLR由信道 冲激响应的估计均值h和信道噪声方差得出：
然后将均值Ei按照从大到小的顺序进行排序，将排序靠前的K个均值Ei选出，并将K个均值Ei对应的子信道作为信息位集合，也即信息传输信道，将信息位集合输入至Polar编码模块。最后根据包含信息位集合的Polar编码模块对初始序列进行编码。相应的，所述根据所述信息位集合，对所述初始序列进行编码包括如下步骤：获取生成矩阵；根据所述信息位的集合和所述生成矩阵，对所述初始序列进行编码。
具体地，极化码的生成矩阵可以获取到，为GN，通常在极化码的编码过程中，将所述初始序列乘以所述生成矩阵GN，得到以完成对所述初始序列的编码。但是在本实施例中，应用高斯近似准则后，将所述信息传输信道作为信息位集合，用A表示。其中，A是生成矩阵GN中矩阵行数的个数的一个子集，得到实现对初始序列的编码。其中，GN(A)是生成矩阵GN中A集合对应的行构成的矩阵，Ac是A的补集。极化码编码表示为其中，N为码长，K为A中元素的个数，A为信息位，为冻结位。如图3所示，在时变信道中，采用高斯近似构造方法时，不同码长的Polar码误码率随信噪比的变化曲线，由图3可知，在信造比较低时，码长2048的误码率值相对最高，其次是码长1024和码长512的误码率值。随着信噪比增大，码长2048的误码率曲线最先开始衰减且衰减幅度最大，其次是码长1024和码长512的误码率曲线。在信噪比较大时，码长越大的误码率值越小。码长2048的误码率相对码长1024的误码率有约0.7dB增益，码长1024的误码率相对码长512的误码率有约0.5dB增益。从图3中可以得出结论：在时变信道中，不同码长的Polar码误码率曲线变化规律同样符合信道极化的性质，码长越长，信道极化效果越明显，误码率曲线随信噪比衰落越快。
在一种实现方式中，所述极化码解码和所述极化码编码均基于相同的极化构造结果，即信息位集合。
具体地，解码是编码的逆过程，在本实施例中也一样，极化码解码和极化码编码都是应用了高斯近似法构造的信息位集合，也即排序靠前的K个均值Ei对应的子信道，是信息传输信道，是信道容量趋近于1的信道。这样，u1 N采用排序靠前的K个均值Ei对应的水声子信道(信息传输信道)得到编码序列x1 N，编码序列x1 N经过OFDM水声通信系统得到接收序列y1 N，由Polar编译码与水声信道相结合形成虚拟子信道，即
相关技术中，LS方法的信道估计结果在低信噪比情况下受到信道噪声影响，且在时变信道中仅采用训练序列估计无法及时得出信道变化信息。为了改进LS方法的信道估计性能，采用将OFDM接收端所有子载波上的接收信息用于信道估计，并与导频序列的LS估计结果结合的方法，可以补充LS 估计结果中的信道变化信息。
在OFDM系统中，每帧数据传输五组OFDM符号数据，本申请将极化码的译码与OFDM信道估计结合，采用块间处理的信道估计方式，即通过前一个OFDM块的信道估计结果用于当前OFDM块的译码。在时变信道中，将块间处理的信道估计方式与基于导频信号的信道估计方法相结合，设置一种借助信道译码估计值的迭代接收机，从而提高信道估计准确性，减少导频子载波系统的使用。
在一种实现方式中，所述将基于导频信号的信道估计方式与块间处理的信道估计方式融合后进行信道估计包括如下步骤：将接收信号从时域转换到频域，得到预处理信号；基于所述预处理信号中的导频信号对信道进行估计，得到当前OFDM符号对应的第一信道传递函数；获取前一个OFDM符号对应的译码信号；根据前一个OFDM符号对应的译码信号，得到前一个OFDM符号对应的第二信道传递函数；将当前OFDM符号对应的第一信道传递函数和前一个OFDM符号对应的第二信道传递函数进行融合，得到混合信道传递函数。
具体地，如图4所示，对于接收到的第m帧信号，将接收信号通过FFT从时域转换到频域，得到预处理信号，预处理信号中包含导频信号，对于第一组OFDM序列，基于导频信号进行信道估计得到第一信道传递函数后，仅采用进行信道均衡和译码，假定该组第一个OFDM符号译码输出值准确，获取该OFDM符号对应的译码信号；将该OFDM符号对应的译码信号进行极化码重编码和信道调制，得到调制信号；然后根据所述调制信号和所述预处理信号对信道进行估计，得到第二信道传递函数，也即结合预处理输出的相应序列，可得出相应的信道估计值(第二信道传递函数)为：
其中，ym(n-1)表示第m帧接收信号中的第n-1组OFDM序列，表示其对应译码输出序列经过重编码和QPSK调制的输出序列。
得到第一信道函数和第二函数后，将当前OFDM符号对应的第一信道传递函数和前一个OFDM符号对应的第二信道传递函数进行融合，得到混合信道传递函数。在本实施例中，将迭代译码估计值(也即第二信道传递函数)和第一信道传递函数输入混合估计模块，用于第n组OFDM序列的信道估计，对第一信道传递函数和第二信道传递函数进行加权平均，定义加权系数δ∈(0，1)，则混合信道估计(也即混合信道传递函数)的输出为：
在一种实现方式中，将初始序列进行极化码编码和调制处理之后包括如下步骤：将进行极化码编码和调制处理后的初始序列进行符号映射、串并转换、子载波分配、导频插入、快速傅里叶逆变换、循环前缀的添加处理和并串转换。
具体地，为避免或减小水声信道多径传输导致的符号间干扰(Inter Symbol Interference,ISI)，在每一组OFDM符号前插入循环前缀CP作为保护间隔(Guard Interval,GI)，CP的时间长度Tcp应大于水声信道的最大多径时延Tch。上述其他处理过程为现有技术，在此不再赘述。
在一种实现方式中，将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码包括如下步骤：将包含噪声的声波进行模数转换、串并转换、循环前缀的移除处理、快速傅里叶变换、混合信道估计、均衡、导频的去除处理、并串转换、解调和极化码译码，得到译码序列。上述处理过程为现有技术，在此不再赘述。
基于上述实施例，本申请还提供了一种智能终端，其原理框图可以如图5所示。该智能终端包括通过系统总线连接的处理器、存储器、网络接口、显示屏、温度传感器。其中，该智能终端的处理器用于提供计算和控制能力。该智能终端的存储器包括非易失性存储介质、内存储器。该非易失性存储介质存储有操作系统和计算机程序。该内存储器为非易失性存储介质中的操作系统和计算机程序的运行提供环境。该智能终端的网络接口用于与外部的终端通过网络连接通信。该计算机程序被处理器执行时以实现一种基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法。该智能终端的显示屏可以是液晶显示屏或者电子墨水显示屏，该智能终端的温度传感器是预先在智能终端内部设置，用于检测内部设备的运行温度。
本领域技术人员可以理解，图5中的原理图，仅仅是与本申请方案相关的部分结构的框图，并不构成对本申请方案所应用于其上的智能终端的限定，具体的智能终端可以包括比图中所示更多或更少的部件，或者组合某些部件，或者具有不同的部件布置。
在一个实施例中，提供了一种智能终端，包括有存储器，以及一个或者一个以上的程序，其中一个或者一个以上程序存储于存储器中，且经配置以由一个或者一个以上处理器执行所述一个或者一个以上程序包含用于进行以下操作的指令：
采用高斯近似改进法构造的极化码对初始序列进行编码包括：
对OFDM水声系统的信道进行仿真，确定所述信道具有信道高斯近似准则；其中，所述高斯近似准则用于表征信道具有高斯近似的特性；
基于高斯近似准则的信道构造极化码，并对初始序列进行编码。
在一种实现方式中，所述对OFDM水声系统的信道进行仿真，确定所述 信道具有信道高斯近似准则包括：
对OFDM水声系统的水声信道进行仿真，确定每个子载波包含复高斯随机噪声；
根据所述复高斯随机噪声，得到每个子载波的噪声方差；
将所有每个子载波的噪声方差进行求和平均，得到信道的噪声方差；
根据信道的噪声方差，确定所述信道具有信道高斯近似准则。
在一种实现方式中，所述根据所述噪声方差，确定所述信道具有信道高斯近似准则包括：
发送导频信号，并在接收端装置对所述导频信号进行信道估计，得到每个子信道的预估信道传递函数；
基于所述噪声方差和每个子信道的预估信道传递函数，确定所述信道具有信道高斯近似准则。
在一种实现方式中，所述信道包括若干子信道；所述基于高斯近似准则的信道构造极化码，并对初始序列进行编码包括：
计算高斯近似准则的每个一阶子信道的若干对数似然比；
递推计算每个N阶子信道的若干对数似然比的均值；
将所有子信道的均值按照从大到小的顺序进行排序；
将排序靠前的若干子信道作为信息位集合；
获取生成矩阵；
根据所述信息位的集合和所述生成矩阵，对所述初始序列进行编码。
在一种实现方式中，所述将基于导频信号的信道估计方式与块间处理的信道估计方式融合后进行信道估计包括：
将接收信号从时域转换到频域，得到预处理信号；
基于所述预处理信号中的导频信号对信道进行估计，得到当前OFDM符号对应的第一信道传递函数；
获取前一个OFDM符号对应的译码信号；
根据前一个OFDM符号对应的译码信号，得到前一个OFDM符号对应的第二信道传递函数；
将当前OFDM符号对应的第一信道传递函数和前一个OFDM符号对应的第二信道传递函数进行融合，得到混合信道传递函数。
在一种实现方式中，所述根据前一个OFDM符号对应的译码信号，得到前一个OFDM符号对应的第二信道传递函数包括：
将前一个OFDM符号对应的译码信号进行极化重编码和信道调制，得到调制信号；
根据所述调制信号和所述预处理信号对信道进行估计，得到第二信道传递函数。
在一种实现方式中，将初始序列进行极化码编码和调制处理之后包括：
将进行极化码编码和调制处理后的初始序列进行符号映射、串并转换、 子载波分配、导频插入、快速傅里叶逆变换、循环前缀的添加处理和并串转换。
在一种实现方式中，将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码包括：
将包含噪声的声波进行模数转换、串并转换、循环前缀的移除处理、快速傅里叶变换、混合信道估计、均衡、导频的去除处理、并串转换、解调和极化码译码，得到译码序列。
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，所述的计算机程序可存储于一非易失性计算机可读取存储介质中，该计算机程序在执行时，可包括如上述各方法的实施例的流程。其中，本申请所提供的各实施例中所使用的对存储器、存储、数据库或其它介质的任何引用，均可包括非易失性和/或易失性存储器。非易失性存储器可包括只读存储器(ROM)、可编程ROM(PROM)、电可编程ROM(EPROM)、电可擦除可编程ROM(EEPROM)或闪存。易失性存储器可包括随机存取存储器(RAM)或者外部高速缓冲存储器。作为说明而非局限，RAM以多种形式可得，诸如静态RAM(SRAM)、动态RAM(DRAM)、同步DRAM(SDRAM)、双数据率SDRAM(DDRSDRAM)、增强型SDRAM(ESDRAM)、同步链路(Synchlink)DRAM(SLDRAM)、存储器总线(Rambus)直接RAM(RDRAM)、直接存储器总线动态RAM(DRDRAM)，以及存储器总线动态RAM(RDRAM)等。
综上所述，本申请公开了一种基于高斯近似改进极化码的译码级联迭代水声通信系统，系统包括：发射端装置，用于将初始序列进行极化码编码和调制处理，得到OFDM信号，并发射包含OFDM信号的声波；接收端装置，用于在水声信道接收包含噪声的声波，并将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码，得到译码序列；本申请实施例在发射端采用基于高斯近似改进法构造极化码的编码技术可根据水声信道特点，形成不同的传输编码方案，使得整个通信系统在不同信道条件下具有环境适应性，在接收端采用混合信道估计，提高信道估计准确性，将混合信道估计模块、均衡器与极化码译码器级联，构成循环迭代运算，提高整个通信系统的性能。
基于上述实施例，本申请公开了一种基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法，应当理解的是，本申请的应用不限于上述的举例，对本领域普通技术人员来说，可以根据上述说明加以改进或变换，所有这些改进和变换都应属于本申请所附权利要求的保护范围。

Claims (13)

  1. 一种基于高斯近似改进极化码的译码级联迭代水声通信系统，其中，所述系统包括：
    发射端装置，用于将初始序列进行极化码编码和调制处理，得到OFDM信号，并发射包含OFDM信号的声波；其中，所述极化码基于高斯近似改进法构造；
    接收端装置，用于在水声信道接收包含噪声的声波，并将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码，得到译码序列；其中，所述接收端装置中的极化码译码器与混合信道估计模块、均衡器级联，形成循环迭代。
  2. 根据权利要求1所述的基于高斯近似改进极化码的译码级联迭代水声通信系统，其中，所述发射端装置包括：
    第一极化码编码器，用于采用高斯近似改进法构造的极化码对初始序列进行编码，得到编码信号；
    第一信道调制器，用于对所述编码信号进行QPSK调制；
    OFDM调制器，用于对QPSK调制后的信号进行OFDM调制；
    数模转换器，用于将数字信号转换成模拟信号；
    发射换能器，用于在水声信道发射声波。
  3. 根据权利要求1所述的基于高斯近似改进极化码的译码级联迭代水声通信系统，其中，所述接收端装置包括：
    接收换能器，用于在水声信道接收声波；
    模数转换器，用于将模拟信号转换成数字信号；
    混合信道估计模块，用于将基于导频信号的信道估计方式与块间处理的信道估计方式融合后进行信道估计；其中，所述块间处理的信道估计方式为根据前一个OFDM块的信道估计结果来进行当前OFDM块的译码；
    信道均衡器，用于对信道的特性进行补偿；
    OFDM解调器，用于对信道均衡器输出的信号进行OFDM解调；
    信道解调器，用于对OFDM解调器解调后信号进行QPSK解调；
    极化码译码器，用于对信道解调器输出的信号进行译码；
    第二极化码编码器，用于将所述极化码译码器译码后的信号进行重编码；
    第二信道调制器，用于将所述极化码编码器编码后的信号进行QPSK调制；
    块间处理的信道估计模块，用于根据前一个OFDM块的信道估计结果来进行当前OFDM块的译码。
  4. 一种如权利要求1-3任一项所述的基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法，其中，采用高斯近似改进法构造 的极化码对初始序列进行编码包括：
    对OFDM水声系统的信道进行仿真，确定所述信道具有信道高斯近似准则；其中，所述高斯近似准则用于表征信道具有高斯近似的特性；
    基于高斯近似准则的信道构造极化码，并对初始序列进行编码。
  5. 根据权利要求4所述的基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法，其中，所述对OFDM水声系统的信道进行仿真，确定所述信道具有信道高斯近似准则包括：
    对OFDM水声系统的水声信道进行仿真，确定每个子载波包含复高斯随机噪声；
    根据所述复高斯随机噪声，得到每个子载波的噪声方差；
    将所有每个子载波的噪声方差进行求和平均，得到信道的噪声方差；
    根据信道的噪声方差，确定所述信道具有信道高斯近似准则。
  6. 根据权利要求5所述的基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法，其中，所述根据所述噪声方差，确定所述信道具有信道高斯近似准则包括：
    发送导频信号，并在接收端装置对所述导频信号进行信道估计，得到每个子信道的预估信道传递函数；
    基于所述噪声方差和每个子信道的预估信道传递函数，确定所述信道具有信道高斯近似准则。
  7. 根据权利要求6所述的基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法，其中，所述信道包括若干子信道；所述基于高斯近似准则的信道构造极化码，并对初始序列进行编码包括：
    计算高斯近似准则的每个一阶子信道的若干对数似然比；
    递推计算每个N阶子信道的若干对数似然比的均值；
    将所有子信道的均值按照从大到小的顺序进行排序；
    将排序靠前的若干子信道作为信息位集合；
    获取生成矩阵；
    根据所述信息位的集合和所述生成矩阵，对所述初始序列进行编码。
  8. 根据权利要求4所述的基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法，其中，所述将基于导频信号的信道估计方式与块间处理的信道估计方式融合后进行信道估计包括：
    将接收信号从时域转换到频域，得到预处理信号；
    基于所述预处理信号中的导频信号对信道进行估计，得到当前OFDM符号对应的第一信道传递函数；
    获取前一个OFDM符号对应的译码信号；
    根据前一个OFDM符号对应的译码信号，得到前一个OFDM符号对应的第二信道传递函数；
    将当前OFDM符号对应的第一信道传递函数和前一个OFDM符号对应的第 二信道传递函数进行融合，得到混合信道传递函数。
  9. 根据权利要求8所述的基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法，其中，所述根据前一个OFDM符号对应的译码信号，得到前一个OFDM符号对应的第二信道传递函数包括：
    将前一个OFDM符号对应的译码信号进行极化重编码和信道调制，得到调制信号；
    根据所述调制信号和所述预处理信号对信道进行估计，得到第二信道传递函数。
  10. 根据权利要求4所述的基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法，其中，将初始序列进行极化码编码和调制处理之后包括：
    将进行极化码编码和调制处理后的初始序列进行符号映射、串并转换、子载波分配、导频插入、快速傅里叶逆变换、循环前缀的添加处理和并串转换。
  11. 根据权利要求4所述的基于高斯近似改进极化码的译码级联迭代水声通信系统的信号处理方法，其中，将包含噪声的声波进行模数转换、混合信道估计、均衡、解调和极化码译码包括：
    将包含噪声的声波进行模数转换、串并转换、循环前缀的移除处理、快速傅里叶变换、混合信道估计、均衡、导频的去除处理、并串转换、解调和极化码译码，得到译码序列。
  12. 一种智能终端，其中，包括有存储器，以及一个或者一个以上的程序，其中一个或者一个以上程序存储于存储器中，且经配置以由一个或者一个以上处理器执行所述一个或者一个以上程序包含用于执行如权利要求4-11中任意一项所述的方法。
  13. 一种非临时性计算机可读存储介质，其中，当所述存储介质中的指令由电子设备的处理器执行时，使得电子设备能够执行如权利要求4-11中任意一项所述的方法。
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