CN114629766B - Symbol decision method, device, electronic equipment and storage medium in optical fiber communication - Google Patents
Symbol decision method, device, electronic equipment and storage medium in optical fiber communication Download PDFInfo
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- 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
- H04L27/36—Modulator circuits; Transmitter circuits
- H04L27/362—Modulation using more than one carrier, e.g. with quadrature carriers, separately amplitude modulated
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
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- H04B10/616—Details of the electronic signal processing in coherent optical receivers
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- 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
- H04L27/3818—Demodulator circuits; Receiver circuits using coherent demodulation, i.e. using one or more nominally phase synchronous carriers
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Abstract
The invention provides a symbol judgment method, a device, electronic equipment and a storage medium in optical fiber communication, wherein the symbol judgment method in the optical fiber communication comprises the following steps: receiving an optical signal and a local carrier signal, and generating a quadrature modulation signal based on the optical signal and the local carrier signal; dividing the quadrature modulated signal into two paths of signals; determining a symbol decision loss function based on the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals; and processing the two paths of signals based on the symbol decision loss function to obtain symbol decision results of the two paths of signals. The symbol judgment method, the device, the electronic equipment and the storage medium in the optical fiber communication can solve the defect that the symbol of the multi-signal point in the prior art has error judgment, and improve the accuracy of symbol judgment in the optical fiber communication.
Description
Technical Field
The present invention relates to the field of signal processing technologies, and in particular, to a symbol decision method, apparatus, electronic device, and storage medium in optical fiber communication.
Background
With the increasing demand for high spectral efficiency of high-speed and large-capacity optical fiber communication systems, probability forming technology is becoming the mainstream of high-speed and long-distance transmission technology, and has been adopted by the relevant international standards organization as one of the technical standards for long-distance transmission. However, the influence of the probability shaping technology on the traditional symbol decision technology limits the transmission performance of the optical signal, and the solution of the problem lacks relevant theoretical and experimental support work. In order to effectively improve the spectral efficiency and transmission performance of the system, the influence of the probability shaping technology on the symbol decision technology needs to be focused, and a corresponding solution is needed to be proposed.
The probability forming technology can enable the symbol decision boundary to deviate from the original decision boundary, so that more signal points are wrongly decided, and obvious performance damage occurs.
Disclosure of Invention
The invention provides a symbol judgment method, a device, electronic equipment and a storage medium in optical fiber communication, which are used for solving the defect that a symbol of a plurality of signal points in the prior art is subjected to error judgment, and improving the accuracy of symbol judgment in optical fiber communication.
The invention provides a symbol judgment method in optical fiber communication, which comprises the following steps:
receiving an optical signal and a local carrier signal, and generating a quadrature modulation signal based on the optical signal and the local carrier signal;
dividing the quadrature modulated signal into two paths of signals;
determining a symbol decision loss function based on the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals;
and processing the two paths of signals based on the symbol decision loss function to obtain symbol decision results of the two paths of signals.
The symbol judgment method in the optical fiber communication provided by the invention further comprises the following steps:
traversing a preset tap coefficient range, and determining a tap coefficient with the lowest bit error rate of the symbol decision result as an optimization coefficient;
and optimizing the partial response filter based on the optimization coefficient.
According to the symbol decision method in optical fiber communication provided by the invention, the symbol decision loss function is determined based on the noise variance of the two paths of signals and the probability value of the corresponding symbol of the two paths of signals, and the symbol decision loss function comprises the following steps:
the symbol decision loss function is determined based on the following formula:
the AM is an accumulated metric value corresponding to a symbol decision loss function and is used for selecting an optimal symbol sequence; y is Y k Is the symbol corresponding to two paths of signals, H PF Is a partial response filter, X is a candidate sequence, σ 2 Is the noise variance of the two signals, p (X) k ) Is the symbol decision result X k Is a probability of (2).
According to the symbol decision method in optical fiber communication provided by the invention, the symbol decision result of the two paths of signals is obtained by processing the two paths of signals based on the symbol decision loss function, and the symbol decision method comprises the following steps:
and determining a bit sequence corresponding to the minimum accumulated metric value in the two paths of signals based on the symbol decision loss function, and taking the bit sequence as a decision result of the two paths of signals.
According to the symbol decision method in optical fiber communication provided by the invention, the method for dividing the quadrature modulation signal into two paths of signals comprises the following steps:
performing clock signal recovery and equalization processing on the quadrature modulation signal, and eliminating clock frequency difference between an arbitrary waveform generator corresponding to the quadrature modulation signal and a coherent receiver to obtain a first processing signal;
carrying out carrier frequency recovery processing and carrier phase recovery processing on the first processing signal to obtain a second processing signal;
dividing the second processed signal into two paths of signals.
The symbol judgment method in the optical fiber communication provided by the invention further comprises the following steps:
and determining the noise variance of the two paths of signals based on the training sequence added by the optical signal, the length of the training sequence and the optical signal.
The invention also provides a symbol judgment device in optical fiber communication, which comprises:
the first processing module is used for receiving the optical signal and the local carrier signal and generating a quadrature modulation signal based on the optical signal and the local carrier signal;
the second processing module is used for dividing the quadrature modulation signal into two paths of signals;
the loss determination module is used for determining a symbol decision loss function based on the partial response filter, the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals;
and the judging module is used for processing the two paths of signals based on the symbol judgment loss function to obtain symbol judgment results of the two paths of signals.
The invention also provides an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the symbol decision method in optical fiber communication as described in any one of the above when executing the program.
The present invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the symbol decision method in optical fiber communication as described in any of the above.
The invention also provides a computer program product comprising a computer program which when executed by a processor carries out the steps of a symbol decision method in optical fibre communication as described in any one of the above.
The symbol decision method, the device, the electronic equipment and the storage medium in the optical fiber communication provided by the invention determine the symbol decision loss function through the partial response filter, the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals, process the two paths of signals through the symbol decision loss function, and can adjust the decision boundary of the symbol, thereby avoiding the influence of the probability change of the two-side signals on the decision boundary caused by different distribution probability of each constellation point in the probability forming signal, solving the defect that the symbol of the multiple signal points in the prior art has wrong decision, and realizing the improvement of the accuracy of the symbol decision in the optical fiber communication.
Drawings
In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a symbol decision method in optical fiber communication provided by the invention;
FIG. 2 is a schematic diagram showing the differences between conventional symbol decisions provided by the present invention and symbol decisions provided by the present invention;
fig. 3 is a schematic diagram of a signal transmission system corresponding to a symbol decision method in optical fiber communication according to the present invention;
FIG. 4 is a schematic diagram of the frequency response of the partial response filter provided by the present invention;
FIG. 5 is a graph showing the correspondence between the optical signal to noise ratio and the bit error rate provided by the invention;
FIG. 6 is a graph showing the correspondence between the signal transmitting power and the bit error rate provided by the invention;
FIG. 7 is a graph of the correspondence between signal transmit power and normalized generalized mutual information provided by the present invention;
FIG. 8 is a schematic diagram of a symbol decision device in optical fiber communication according to the present invention;
fig. 9 is a schematic structural diagram of an electronic device provided by the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The symbol decision method, apparatus, electronic device and storage medium in optical fiber communication of the present invention are described below with reference to fig. 1 to 9.
As shown in fig. 1, the symbol decision method in optical fiber communication provided by the present invention includes:
step 110, receiving an optical signal and a local carrier signal, and generating a quadrature modulated signal based on the optical signal and the local carrier signal.
It will be appreciated that the optical signal may be obtained by:
the pseudo-random code module generates a data bit sequence required by a user for subsequent processing;
the probability shaping mapping module generates symbol data obeying specific probability distribution according to the data bit sequence generated by the pseudo-random code module, and provides the symbol data for modulation mapping;
the modulation mapping module generates a coherent communication system signal, namely a square wave signal, based on the symbol data output by the probability shaping mapping module;
the root cosine shaping module carries out root cosine shaping on the square wave signal generated by the modulation mapping module and then outputs an electric domain digital signal, thereby improving the anti-interference characteristic of the square wave signal;
the arbitrary waveform generator converts signals output by the root cosine molding module into electric domain digital signals and outputs electric domain analog signals;
the electric amplifier carries out voltage linear amplification on the electric domain analog signal and then outputs the voltage linear amplification;
the external tuning laser generates an optical carrier signal with a specific frequency;
the modulator modulates the amplified electric domain analog signal output by the electric amplifier onto an optical carrier signal to realize electro-optic modulation and output an initial optical signal;
amplifying the initial optical signal by a first erbium-doped optical fiber amplifier to obtain a first amplified optical signal;
the adjustable attenuator is combined with the first erbium-doped fiber amplifier at the front end to control the fiber-entering power of the first amplified optical signal;
the optical fiber loop is an actual link of optical signal transmission and is used for transmitting the first amplified optical signal;
a second erbium-doped fiber amplifier: carrying out power amplification on the transmitted first amplified optical signal to obtain a second amplified optical signal, so that the second amplified optical signal meets the power requirement of a receiving end;
the optical band-pass filter filters out the out-of-band noise introduced by the front-end amplifier (i.e., the first erbium-doped fiber amplifier and the second erbium-doped fiber amplifier) in the second amplified optical signal, so as to obtain the optical signal in step 110 and output the optical signal.
The local carrier signal is obtained based on a local oscillator laser, the local oscillator laser is a local optical carrier generating device at a receiving end, and a local carrier is provided for a coherent receiver.
A coherent receiver: according to the coherent receiving system, the coherent receiving of the optical signal and the local carrier signal is completed.
Further, the optical signal output from the optical bandpass filter is coherently detected based on the local carrier signal, and the carried signal, that is, the quadrature modulation signal is recovered.
Step 120, dividing the quadrature modulation signal into two paths of signals.
It can be understood that the optical signal output by the optical bandpass filter is a signal in the form of a complex signal, for example, a+bi signal, a and b are two paths of signals corresponding to the quadrature modulation signal, a is an I path signal, and b is a Q path signal.
Step 130, determining a symbol decision loss function based on a partial response filter (partial response filter), the noise variance of the two signals, and probability values of corresponding symbols of the two signals.
It will be appreciated that existing symbol decision means, whetherWhether it is a uniformly distributed Signal (UD Signal) or a probability shaped Signal (PS Signal), the decision boundaries of which are at V as shown in FIG. 2 UD Where is caused to be between V PS And V UD The signal in between is subjected to a large number of erroneous decisions, introducing a large performance penalty, so that for a probability shaped signal, its optimal decision function level should be V PS Where it is located. To achieve this, the loss function in making the symbol decisions needs to be redefined based on the partial response filter, the noise variance of the two signals, and the probability values of the corresponding symbols of the two signals.
The difference between the novel decision technique of the probability shaped signal and the conventional decision technique is illustrated in fig. 2. V (V) PS Indicated is a decision boundary, V, corresponding to a symbol decision technique in optical fiber communications UD Indicated are decision boundaries for conventional symbol decisions. It can be seen that the decision boundaries of the two symbols are significantly different, and the reason for the deviation is that the probability of distribution of each constellation point in the probability shaping Signal (PS Signal) is different, and the decision boundaries are affected by the probability variation of the two signals. When the probabilities of the symbols are equal (UD Signal), the decision boundary (V UD ) Then it is the average of the two adjacent symbols.
The present invention provides a signal transmission system as shown in fig. 3, namely a PS-16QAM platform for 64-GBaud. The digital signal processing algorithm of the transmitting end is as follows: the 14-order pseudo-random code is used as an information source, and the quadrature and in-phase branches are respectively subjected to probability shaping mapping and root raised cosine shaping. The generated PS-16QAM signal is fed into any waveform generator, after passing through a pair of drivers with 70-GHz electric bandwidth, the amplified radio frequency signal is loaded onto an optical carrier with a central wavelength of 1550.14nm by a single-bias IQ Mach-Zehnder modulator, and the bias voltage of the modulator is set to be zero. The synthesized signal is sent into an optical fiber through an attenuator and a first erbium-doped optical fiber amplifier, is sent into a digital real-time oscilloscope with 80GSa/s sampling rate and 32-GHz bandwidth for receiving after being transmitted by multiple transmission distances and then is sent into a second erbium-doped optical fiber amplifier and an optical band-pass filter, and is subjected to subsequent digital signal processing on MATLAB software.
And 140, processing the two paths of signals based on the symbol decision loss function to obtain symbol decision results of the two paths of signals.
It can be understood that when symbol decision is performed, modulation demapping is required to be performed on the two paths of signals, an existing euclidean distance calculation scheme needs to be improved during demapping, and symbol decision boundaries are optimized to obtain demapping output with excellent performance.
In some embodiments, the symbol decision method in optical fiber communication further comprises:
traversing a preset tap coefficient range, and determining a tap coefficient with the lowest bit error rate of the symbol decision result as an optimization coefficient;
and optimizing the partial response filter based on the optimization coefficient.
It can be understood that, according to the comparison of the bit sequence generated after modulation and demapping and the bit sequence before modulation and demapping, the number of error bits N is counted, and the total number of bits M output after modulation and demapping is operated to obtain the bit error rate e=n/M; the process from step 110 to step 140 is a modulation demapping process.
Partial response filter H PF Is an important auxiliary technique for implementing modulation demapping, and its Z-domain expression can be expressed as:
H PF (z)＝1+αz -1
in this expression, H is uniquely affected PF The technical characteristics are that the tap coefficients alpha, different alpha can lead to H PF The 3-dB bandwidth of (c) is different and reference is made in particular to figure 4.
It can be seen that at different tap coefficients α, H PF The amplitude-frequency response of (a) will be obviously different, and H is increased along with the increase of the tap coefficient alpha PF Becomes steeper and steeper, which also means H PF The in-band noise of the signal can be compressed more effectively, but a larger alpha can introduce larger intersymbol interference while suppressing the in-band noise, thereby deteriorating the performance of the signal. There is a trade-off between alpha and performance, and therefore we will be at a presetTap coefficient range [0,1]The tap coefficient is traversed by taking 0.1 as a step length in the range of (2), so that the optimal coefficient with the lowest error rate is found, and the optimally designed partial response filter is further realized.
The probability of the candidate sequence (candidate symbol or candidate sequence) is provided according to the probability distribution of the symbols formed after the modulation mapping.
Determination of the surviving sequence (survival sequence) x= (X) 1 、X 2 、…、Xi、…X k ):
In the course of modulation demapping of signal, in the signal transmission system provided by the invention, every Xi (i E [1, k)]) There are 4 possible values, i.e. Xi E { -3, -1, 3} (i E [1, k)]) Thus, during modulation demapping of the signal, there will be 4 k Different combinations can be generated in the dictionary order in mathematics, so that 4 can exist k The modulation and demapping scheme provided by the invention outputs a corresponding arrangement mode according to the minimum AM value, namely, determines a bit sequence corresponding to the output survivor sequence from the candidate sequence according to the minimum AM value, namely, the symbol judgment result of the two paths of signals, namely, the modulation and demapping is completed.
In some embodiments, the determining a symbol decision loss function based on the partial response filter, the noise variance of the two signals, and the probability value of the corresponding symbol of the two signals includes:
the symbol decision loss function is determined based on the following formula:
the AM is an accumulated metric value corresponding to a symbol decision loss function and is used for selecting an optimal symbol sequence; DM (DM) k Is a loss function based on Euclidean distance, OM k Is a correction term added in the loss function, Y k Is the symbol corresponding to two paths of signals, H PF Is a partial response filter, X is a candidate sequence, σ 2 Is the noise of two paths of signalsAcoustic variance, p (X) k ) Is the symbol decision result X k Is a probability of (2).
In some embodiments, the processing the two signals based on the symbol decision loss function to obtain symbol decision results of the two signals includes:
and determining a bit sequence corresponding to the minimum accumulated metric value in the two paths of signals based on the symbol decision loss function, and taking the bit sequence as a decision result of the two paths of signals.
It can be appreciated that a series of sequences x= (X) is found from the loss function 1 、X 2 、……X k ) And (5) enabling the AM value to be minimum, and obtaining the modulation de-mapping scheme under the optimization judgment.
In some embodiments, the dividing the quadrature modulated signal into two signals includes:
performing clock signal recovery and equalization processing on the quadrature modulation signal, and eliminating clock frequency difference between an arbitrary waveform generator corresponding to the quadrature modulation signal and a coherent receiver to obtain a first processing signal;
carrying out carrier frequency recovery processing and carrier phase recovery processing on the first processing signal to obtain a second processing signal;
dividing the second processed signal into two paths of signals.
It will be appreciated that the steps of this embodiment may refer to fig. 2, and clock recovery and equalization is shown in fig. 2: the clock signal recovery of the signal is completed, the clock frequency difference between the arbitrary waveform generator and the coherent receiver is eliminated, the signal quality is improved, and meanwhile, the equalization technology can compensate the inter-symbol crosstalk and the linear damage in the link, and the signal quality is improved.
Carrier frequency recovery: carrier frequency drift caused by a fixed frequency difference existing between the local oscillator laser and the external tuned laser is eliminated.
Carrier phase recovery: phase noise in the external tuned laser is eliminated.
Modulation demapping: according to the scheme of the invention, the demapping of the signal is carried out.
In some embodiments, the symbol decision method in optical fiber communication further comprises:
and determining the noise variance of the two paths of signals based on the training sequence added by the optical signal, the length of the training sequence and the optical signal.
It will be appreciated that the noise variance of the two signals can be estimated by adding a training sequence, i.e. at the beginning of transmitting the corresponding optical signals of the two signals, we transmit a signal of length L t Training sequence T of (1) t The noise variance can be estimated as:
wherein r is t Is an optical signal received from a channel, T t Is a training sequence, L t Is the length of the training sequence.
In some embodiments, the symbol decision method in optical fiber communication provided by the present invention further includes:
and counting the error rate, namely comparing the bit sequence generated after modulation and demapping with the bit sequence before modulation and demapping, counting the number N of error bits, and calculating the number N of error bits with the total number M of bits output after modulation and demapping to obtain the error rate E=N/M.
The symbol decision method in the optical fiber communication provided by the invention has the advantages that the relation between the corresponding optical signal to noise ratio and the corresponding error ratio of the error ratio is shown in fig. 5, the relation between the optical signal to noise ratio and the corresponding error ratio of the symbol decision method provided by the invention is shown by a line 1 in fig. 5, and the relation between the optical signal to noise ratio and the corresponding error ratio of the existing symbol decision method is shown by a line 2 in fig. 5. After passing through a 3200 km standard single-mode fiber, the relationships between different transmitting powers (the power of the optical signal entering the optical fiber loop) and the error rate and normalized generalized mutual information are shown in fig. 6 and 7 respectively.
Line 1 in fig. 6 shows the relationship between the transmission power and the bit error rate corresponding to the symbol decision method provided by the present invention, and line 2 in fig. 6 shows the relationship between the transmission power and the bit error rate corresponding to the existing symbol decision method.
Line 1 in fig. 7 shows the relationship between the transmission power and the normalized generalized mutual information corresponding to the symbol decision method provided by the present invention, and line 2 in fig. 7 shows the relationship between the transmission power and the normalized generalized mutual information corresponding to the existing symbol decision method.
In summary, the symbol decision method in optical fiber communication provided by the present invention includes: receiving an optical signal and a local carrier signal, and generating a quadrature modulation signal based on the optical signal and the local carrier signal; dividing the quadrature modulated signal into two paths of signals; determining a symbol decision loss function based on the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals; and processing the two paths of signals based on the symbol decision loss function to obtain symbol decision results of the two paths of signals.
In the symbol decision method in the optical fiber communication provided by the invention, the symbol decision loss function is determined based on the partial response filter, the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals, and the symbol decision loss function is used for processing the two paths of signals, so that the decision boundary of the symbol can be adjusted, the influence of the probability change of the two-side signals on the decision boundary caused by different distribution probability of each constellation point in the probability forming signal is avoided, the defect that the symbol of the multiple signal points in the prior art has wrong decision is overcome, and the accuracy of the symbol decision in the optical fiber communication is improved.
The symbol decision device in optical fiber communication provided by the invention is described below, and the symbol decision device in optical fiber communication described below and the symbol decision method in optical fiber communication described above can be referred to correspondingly.
As shown in fig. 8, a symbol decision device 800 in optical fiber communication provided by the present invention includes: the device comprises a first processing module, a second processing module, a loss determination module and a judgment module.
The first processing module is used for receiving the optical signal and the local carrier signal and generating a quadrature modulation signal based on the optical signal and the local carrier signal.
The second processing module is used for dividing the quadrature modulation signal into two paths of signals.
The loss determination module is used for determining a symbol decision loss function based on the partial response filter, the noise variance of the two paths of signals and the probability value of the corresponding symbol of the two paths of signals.
And the judging module is used for processing the two paths of signals based on the symbol judgment loss function to obtain symbol judgment results of the two paths of signals.
In some embodiments, symbol decision device 800 in fiber optic communications further comprises: the device comprises an optimization parameter determining module and a filter determining module.
The optimization parameter determining module is used for traversing the preset tap coefficient range and determining the tap coefficient with the lowest bit error rate of the symbol decision result as the optimization coefficient.
The filter determination module is used for optimizing the partial response filter based on the optimization coefficient.
In some embodiments, the loss determination module is further to determine the symbol decision loss function based on the following formula:
the AM is an accumulated metric value corresponding to a symbol decision loss function and is used for selecting an optimal symbol sequence; DM (DM) k Is a loss function based on Euclidean distance, OM k Is a correction term added in the loss function, Y k Is the symbol corresponding to two paths of signals, H PF Is a partial response filter, X is a candidate sequence, σ 2 Is the noise variance of the two signals, p (X) k ) Is the symbol decision result X k Is a probability of (2).
In some embodiments, the decision module is further configured to determine, based on the symbol decision loss function, a bit sequence corresponding to a minimum accumulated metric value in the two signals, as a decision result of the two signals.
In some embodiments, the second processing module comprises: the device comprises a first signal processing unit, a second signal processing unit and a decomposition unit.
The first signal processing unit is used for carrying out clock signal recovery and equalization processing on the quadrature modulation signal, eliminating clock frequency difference between the random waveform generator corresponding to the quadrature modulation signal and the coherent receiver, and obtaining a first processing signal.
And the second signal processing unit is used for carrying out carrier frequency recovery processing and carrier phase recovery processing on the first processing signal to obtain a second processing signal.
The decomposition unit is used for dividing the second processing signal into two paths of signals.
In some embodiments, symbol decision device 800 in fiber optic communications further comprises: and a noise variance determining module.
The noise variance determining module is used for determining the noise variances of the two paths of signals based on the training sequence added by the optical signals, the length of the training sequence and the optical signals.
The electronic device, the computer program product and the storage medium provided by the invention are described below, and the electronic device, the computer program product and the storage medium described below and the symbol decision method in optical fiber communication described above can be referred to correspondingly.
Fig. 9 illustrates a physical schematic diagram of an electronic device, as shown in fig. 9, which may include: processor 910, communication interface (Communications Interface), memory 930, and communication bus 940, wherein processor 910, communication interface 920, and memory 930 communicate with each other via communication bus 940. Processor 910 can invoke logic instructions in memory 930 to perform a symbol decision method in fiber optic communications, the method comprising:
step 110, receiving an optical signal and a local carrier signal, and generating a quadrature modulation signal based on the optical signal and the local carrier signal;
step 120, dividing the quadrature modulation signal into two paths of signals;
step 130, determining a symbol decision loss function based on the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals;
and 140, processing the two paths of signals based on the symbol decision loss function to obtain symbol decision results of the two paths of signals.
Further, the logic instructions in the memory 930 described above may be implemented in the form of software functional units and may be stored in a computer-readable storage medium when sold or used as a stand-alone product. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
In another aspect, the present invention also provides a computer program product, the computer program product including a computer program, the computer program being storable on a non-transitory computer readable storage medium, the computer program, when executed by a processor, being capable of performing a symbol decision method in optical fiber communication provided by the methods described above, the method comprising:
step 110, receiving an optical signal and a local carrier signal, and generating a quadrature modulation signal based on the optical signal and the local carrier signal;
step 120, dividing the quadrature modulation signal into two paths of signals;
step 130, determining a symbol decision loss function based on the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals;
and 140, processing the two paths of signals based on the symbol decision loss function to obtain symbol decision results of the two paths of signals.
In yet another aspect, the present invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, is implemented to perform a symbol decision method in optical fiber communication provided by the methods described above, the method comprising:
step 110, receiving an optical signal and a local carrier signal, and generating a quadrature modulation signal based on the optical signal and the local carrier signal;
step 120, dividing the quadrature modulation signal into two paths of signals;
step 130, determining a symbol decision loss function based on the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals;
and 140, processing the two paths of signals based on the symbol decision loss function to obtain symbol decision results of the two paths of signals.
The apparatus embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
From the above description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course may be implemented by means of hardware. Based on this understanding, the foregoing technical solution may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a computer readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the respective embodiments or some parts of the embodiments.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (8)
1. A symbol decision method in fiber optic communications, comprising:
receiving an optical signal and a local carrier signal, and generating a quadrature modulation signal based on the optical signal and the local carrier signal;
dividing the quadrature modulated signal into two paths of signals;
determining a symbol decision loss function based on the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals;
processing the two paths of signals based on the symbol decision loss function to obtain symbol decision results of the two paths of signals;
the determining a symbol decision loss function based on the partial response filter, the noise variance of the two paths of signals, and the probability value of the symbol corresponding to the two paths of signals, includes:
the symbol decision loss function is determined based on the following formula:
the AM is an accumulated metric value corresponding to a symbol decision loss function and is used for selecting an optimal symbol sequence; y is Y k Is the symbol corresponding to two paths of signals, H PF Is a partial response filter, X is a candidate sequence, σ 2 Is the noise variance of the two signals, p (X) k ) Is the symbol decision result X k Is a probability of (2).
2. The method for symbol decision in fiber optic communications according to claim 1, further comprising:
traversing a preset tap coefficient range, and determining a tap coefficient with the lowest bit error rate of the symbol decision result as an optimization coefficient;
and optimizing the partial response filter based on the optimization coefficient.
3. The method for symbol decision in optical fiber communication according to claim 1, wherein said processing the two signals based on the symbol decision loss function to obtain symbol decision results of the two signals comprises:
and determining a bit sequence corresponding to the minimum accumulated metric value in the two paths of signals based on the symbol decision loss function, and taking the bit sequence as a decision result of the two paths of signals.
4. The method for symbol decision in optical fiber communication according to claim 1, wherein said dividing said quadrature modulated signal into two signals comprises:
performing clock signal recovery and equalization processing on the quadrature modulation signal, and eliminating clock frequency difference between an arbitrary waveform generator corresponding to the quadrature modulation signal and a coherent receiver to obtain a first processing signal;
carrying out carrier frequency recovery processing and carrier phase recovery processing on the first processing signal to obtain a second processing signal;
dividing the second processed signal into two paths of signals.
5. The symbol decision method in fiber optic communications according to any of claims 1-4, further comprising:
and determining the noise variance of the two paths of signals based on the training sequence added by the optical signal, the length of the training sequence and the optical signal.
6. A symbol decision device in fiber optic communications, comprising:
the first processing module is used for receiving the optical signal and the local carrier signal and generating a quadrature modulation signal based on the optical signal and the local carrier signal;
the second processing module is used for dividing the quadrature modulation signal into two paths of signals;
the loss determination module is used for determining a symbol decision loss function based on the partial response filter, the noise variance of the two paths of signals and the probability value of the symbol corresponding to the two paths of signals;
the judging module is used for processing the two paths of signals based on the symbol judgment loss function to obtain symbol judgment results of the two paths of signals;
the loss determination module is specifically configured to:
the symbol decision loss function is determined based on the following formula:
the AM is an accumulated metric value corresponding to a symbol decision loss function and is used for selecting an optimal symbol sequence; y is Y k Is the symbol corresponding to two paths of signals, H PF Is a partial response filter, X is a candidate sequence, σ 2 Is the noise variance of the two signals, p (X) k ) Is the symbol decision result X k Is a probability of (2).
7. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the symbol decision method in optical fiber communication according to any of claims 1 to 5 when the program is executed.
8. A non-transitory computer readable storage medium having stored thereon a computer program, which when executed by a processor, implements the steps of the symbol decision method in optical fiber communication according to any of claims 1 to 5.
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