A method and system for generating and detecting orthogonal amplitude signals with probability shaping

Abstract

The present invention discloses a method and system for generating and detecting a probabilistically shaped quadrature amplitude modulated signal, relating to the field of optical transmission systems. The method comprises determining a high-order modulated QAM signal to be transmitted by a transmitter, identifying and truncating constellation points with a high bit error rate; re-assigning MB probabilities to the remaining constellation points after truncation to obtain the transmission probabilities of all transmitted quadrature amplitude modulated signals; and receiving the probabilistically shaped quadrature amplitude modulated signal at a receiver based on the original quadrature amplitude signal reception method. The present invention is applicable to signals of different modulation orders and does not change the original signal reception algorithm or process, greatly enhancing its practicality.

Description

Technical Field

[0001] The present invention relates to the field of optical transmission systems, and in particular to a probability-shaped orthogonal amplitude signal generation and detection method, and a probability-shaped orthogonal amplitude signal generation and detection system. Background Art

[0002] With the development of technologies such as the Internet of Things, cloud computing, artificial intelligence, and virtual reality, the demand for network transmission capacity is growing exponentially. Typically, transmission systems employ QAM (Quadrature Amplitude Modulation) technology to improve spectral efficiency during transmission. Probability shaping is a modulation and coding scheme that flexibly modulates the probability distribution of each constellation point in a QAM signal to achieve gain, effectively improving the performance of optical transmission systems.

[0003] Typically, when the channel follows a Gaussian distribution, coding techniques using probability shaping distribute each point using a Maxwell-Boltzmann (MB) distribution with optimal probability to achieve optimal performance. However, when high-order modulation is used, the signal-to-noise ratio requirement increases significantly. Bit errors at the outer constellation points can be significant, and the impact of these errors is often minimized by reducing their probability. However, when the signal-to-noise ratio is too low, the outer probabilities are extremely low, causing the MB-distributed constellation points to be concentrated at the center, significantly compressing spectral efficiency. Therefore, the key challenge in probability shaping is to find a probability distribution model that enables efficient transmission at high-order modulation and low signal-to-noise ratios. Summary of the Invention

[0004] In view of the defects existing in the prior art, the purpose of the present invention is to provide a probability-shaped orthogonal amplitude signal generation and detection method and system, which is applicable to signals of different modulation orders and does not change the original signal receiving algorithm and process, thereby greatly enhancing practicality.

[0005] To achieve the above objectives, the present invention provides a method for generating and detecting a probability-shaped orthogonal amplitude signal, which specifically includes the following steps:

[0006] Determine the high-order modulated QAM signal to be sent by the transmitter, and determine and truncate the constellation points with the highest bit error rate;

[0007] Re-allocate the MB probability of the remaining constellation points after truncation to obtain the transmission probability of all transmitted orthogonal amplitude modulation signals;

[0008] Based on the original orthogonal amplitude signal receiving method, the receiving end receives the orthogonal amplitude modulated signal after probability shaping.

[0009] On the basis of the above technical solution, the steps of determining and truncating the constellation point with a large bit error rate include:

[0010] Determine the constellation point with the largest bit error rate based on the result obtained by sending feedback of the probability coded signal;

[0011] The constellation points with a large bit error rate are truncated.

[0012] Based on the above technical solution, the MB probability allocation is performed again on the remaining constellation points after truncation to obtain the transmission probabilities of all transmitted quadrature amplitude modulation signals. The specific steps include:

[0013] The remaining constellation points after truncation are re-allocated with MB probability according to the required spectrum utilization, so as to obtain the transmission probabilities of all transmitted orthogonal amplitude modulation signals.

[0014] On the basis of the above technical solution, the constellation points remaining after truncation are re-allocated with MB probability according to the required spectrum utilization, wherein the transmission probability of each constellation point after allocation is:

[0015]

[0016] Where P(x) represents the transmission probability of the x-th constellation point, X represents the set of constellation points to be transmitted, v represents the degree of probability shaping, exp represents the exponential function with the natural constant e as the base, Re(x) represents the function taking the real part of x, and Im(x) represents the function taking the imaginary part of x.

[0017] On the basis of the above technical solution, the receiving end receives the quadrature amplitude modulation signal after probability shaping based on the original quadrature amplitude signal receiving method, and the specific steps include:

[0018] At the receiving end, dispersion compensation, signal synchronization, channel compensation, frequency offset and phase compensation, bit mapping and error calculation are performed on the orthogonal amplitude modulation signal after probability shaping to achieve reception of the orthogonal amplitude modulation signal after probability shaping.

[0019] On the basis of the above technical solutions,

[0020] The signal synchronization is used to find the corresponding transmission data frame;

[0021] The channel compensation is used to reduce the distortion introduced by channel damage;

[0022] The channel compensation includes linear compensation and nonlinear compensation.

[0023] On the basis of the above technical solutions,

[0024] The frequency offset phase compensation is used to compensate for the frequency difference and phase difference between the local oscillator laser and the transmitted carrier;

[0025] The bit mapping is used to restore the orthogonal amplitude signal to a bit signal.

[0026] The present invention provides a probability-shaped orthogonal amplitude signal generation and detection system, comprising:

[0027] A determination module is used to determine the high-order modulated QAM signal to be sent by the transmitter, and to determine and truncate the constellation point with a large bit error rate;

[0028] An allocation module, which is used to re-allocate the MB probabilities of the remaining constellation points after truncation to obtain the transmission probabilities of all transmitted orthogonal amplitude modulation signals;

[0029] The receiving module is used to receive the quadrature amplitude modulated signal after probability shaping at the receiving end based on the original quadrature amplitude signal receiving mode.

[0030] On the basis of the above technical solution, the specific process of determining and truncating the constellation point with a large bit error rate includes:

[0031] Determine the constellation point with the largest bit error rate based on the result obtained by sending feedback of the probability coded signal;

[0032] The constellation points with a large bit error rate are truncated.

[0033] Based on the above technical solution, the MB probability allocation is performed again on the remaining constellation points after truncation to obtain the transmission probability of all transmitted orthogonal amplitude modulation signals. The specific process includes:

[0034] The remaining constellation points after truncation are re-allocated with MB probability according to the required spectrum utilization, so as to obtain the transmission probabilities of all transmitted orthogonal amplitude modulation signals.

[0035] Compared with the existing technology, the advantages of the present invention are: it adopts a truncated orthogonal amplitude modulation probability shaping coding method, can modulate according to the characteristics of different channels, on the basis of adopting high-order modulation and under low signal-to-noise ratio conditions, maintains the structure of the original probability shaping system, and uses the coding characteristics to achieve performance improvement; the present invention is applicable to signals of different modulation orders and does not change the receiving algorithm and process of the original signal, greatly enhancing practicality, optimizing the performance of the optical transmission system as a whole, and improving compatibility and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0037] Figure 1 The figure is a flow chart of a probability-shaped orthogonal amplitude signal generation and detection method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0039] The embodiments of the present invention provide a method for generating and detecting orthogonal amplitude signals using probability shaping. Under low signal-to-noise ratio (SNR) conditions, the probability of peripheral constellation points is zero, while the probability of other constellation points is still allocated according to the MB distribution (Maxwell-Boltzmann distribution). This method not only meets the requirements of SNR transmission but also reasonably implements the efficient transmission function of probability shaping coding. As a whole, probability shaping coding transmission with maximum transmission efficiency under low SNR conditions is achieved.

[0040] The system architecture at both the transmitting and receiving ends is identical to the existing system, without adding additional complexity. The difference lies in requiring only probabilistic truncation of peripheral constellation points, followed by a single probabilistic encoding of the constellation points to be transmitted. This system is compatible with existing probabilistic shaping systems, has a simple structure, and the signal transparency of the modulation scheme is applicable to the transmission of orthogonal amplitude signals of different formats, facilitating system protocol upgrades. This invention can effectively enhance the practicality of orthogonal amplitude modulation signals in practical applications, expand the scope of application of probabilistic shaping pulse amplitude modulation technology, and improve the stability, reliability, and scalability of probabilistic shaping systems.

[0041] See also Figure 1 As shown, an embodiment of the present invention provides a method for generating and detecting a probability-shaped orthogonal amplitude signal, which specifically includes the following steps:

[0042] S1: Determine the high-order modulated QAM signal to be sent by the transmitter, and determine and truncate the constellation point with the largest bit error rate;

[0043] In the present invention, the constellation points with a large bit error rate are determined and truncated, and the specific steps include:

[0044] S101: Determine a constellation point with a large bit error rate based on a result obtained by sending feedback of a probability coded signal;

[0045] S102: performing truncation processing on the determined constellation points with a large bit error rate.

[0046] That is, first, the high-order modulated QAM signal to be sent is determined at the transmitting end. Then, based on the results obtained from the conventional probability coded signal transmission feedback, the constellation points with excessively large bit error rates (i.e., the constellation points with bit error rates greater than a preset value) are confirmed. The constellation points with large bit error rates are truncated to make their generation probability zero.

[0047] S2: Re-allocate the MB probabilities of the remaining constellation points after truncation to obtain the transmission probabilities of all transmitted orthogonal amplitude modulation signals;

[0048] In the present invention, MB probability allocation is performed on the remaining constellation points after truncation to obtain the transmission probabilities of all transmitted quadrature amplitude modulation signals. The specific steps include:

[0049] The remaining constellation points after truncation are re-allocated with MB probability according to the required spectrum utilization, so as to obtain the transmission probabilities of all transmitted orthogonal amplitude modulation signals.

[0050] Through steps S1 and S2, under certain signal-to-noise ratio conditions, it is possible to remove some high-bit-error-rate constellation points while maintaining high modulation efficiency, thereby improving the overall system signal transmission performance. After the actual transmitted probability-shaped orthogonal amplitude signal is obtained, it is modulated and sent into the optical fiber for transmission.

[0051] The remaining constellation points after truncation are re-allocated for MB probability according to the required spectrum utilization, where the transmission probability of each constellation point after allocation is:

[0052]

[0053] Where P(x) represents the transmission probability of the x-th constellation point, X represents the set of constellation points to be transmitted, v represents the degree of probability shaping, exp represents the exponential function with the natural constant e as the base, Re(x) represents the function taking the real part of x, and Im(x) represents the function taking the imaginary part of x.

[0054] S3: Based on the original orthogonal amplitude signal reception method, the receiving end receives the orthogonal amplitude modulated signal after probability shaping. Since the orthogonal amplitude signal after probability shaping has no essential structural difference from the original orthogonal amplitude signal, the receiving end can use the original reception method for reception.

[0055] In the present invention, based on the original orthogonal amplitude signal receiving method, the receiving end receives the orthogonal amplitude modulation signal after probability shaping, and the specific steps include:

[0056] At the receiving end, dispersion compensation, signal synchronization, channel compensation, frequency offset and phase compensation, bit mapping and error calculation are performed on the orthogonal amplitude modulation signal after probability shaping to achieve reception of the orthogonal amplitude modulation signal after probability shaping.

[0057] In this invention, signal synchronization is used to find the corresponding transmission data frame; channel compensation is used to reduce distortion introduced by channel impairments; channel compensation includes linear compensation and nonlinear compensation. Frequency offset and phase compensation is used to compensate for the frequency and phase differences between the local oscillator laser and the transmitted carrier; and bit mapping is used to restore the orthogonal amplitude signal to a bit signal.

[0058] The following is a detailed description of the probability-shaped orthogonal amplitude signal generation and detection method of the present invention.

[0059] First, determine the type of quadrature amplitude modulation signal to be transmitted. Set the transmitted signal to QAM-N. Under normal conditions, the number of possible constellation points to be transmitted is N. After conventional transmission and reception, determine the number of peripheral constellation points that affect transmission performance to be M, and set their transmission probability to zero. Remaining constellation points are reassigned using the MB distribution. Based on the required transmission capacity, set the number of bits per symbol required for the required quadrature modulation coding to H.

[0060] According to the MB distribution, the transmission probability of each constellation point is:

[0061]

[0062] Wherein, P(x) represents the transmission probability of the x-th constellation point, X represents the set of constellation points to be transmitted, the number of constellation points in the set is NM, and v represents the degree of probability shaping.

[0063] Therefore, the information entropy H(x) calculated based on probability is:

[0064] H(x)=∑ x∈X P(x)·log2 P(x)

[0065] Based on the required H(x), the required v is obtained, thereby determining the probability of each constellation point to be transmitted. The calculated probability is then used to transmit the QAM-N data at each point (where the probability of point M is zero). This probability distribution allows all transmitted symbols to be transmitted at the maximum information rate using probabilistic shaping coding while maintaining a low signal-to-noise ratio. This reduces the bit error rate of the entire probabilistic shaping system, thereby improving its performance.

[0066] The probability-shaped orthogonal amplitude signal generation and detection method of the embodiment of the present invention adopts a truncated orthogonal amplitude modulation probability shaping coding method, which can be modulated according to the characteristics of different channels. On the basis of adopting high-order modulation and under low signal-to-noise ratio conditions, the structure of the original probability shaping system is maintained, and performance improvement is achieved by utilizing coding characteristics. The present invention is applicable to signals of different modulation orders and does not change the receiving algorithm and process of the original signal, greatly enhancing practicality, optimizing the performance of the optical transmission system as a whole, and improving compatibility and stability.

[0067] An embodiment of the present invention provides a probability-shaped orthogonal amplitude signal generation and detection system, which includes a determination module, a distribution module and a receiving module.

[0068] The determination module is used to determine the high-order modulated QAM signal to be sent by the transmitter, and to determine and truncate the constellation points with a large bit error rate; the allocation module is used to redistribute the MB probability of the remaining constellation points after truncation to obtain the transmission probability of all transmitted orthogonal amplitude modulation signals; the receiving module is used to receive the orthogonal amplitude modulation signal after probability shaping at the receiver based on the original orthogonal amplitude signal receiving method.

[0069] In the present invention, the constellation point with a large bit error rate is determined and truncated, and the specific process includes:

[0070] Determine the constellation point with the largest bit error rate based on the result obtained by sending feedback of the probability coded signal;

[0071] The constellation points with a large bit error rate are truncated.

[0072] In the present invention, MB probabilities are reassigned to the remaining constellation points after truncation to obtain the transmission probabilities of all transmitted quadrature amplitude modulation signals. The specific process includes:

[0073] The remaining constellation points after truncation are re-allocated with MB probability according to the required spectrum utilization, so as to obtain the transmission probabilities of all transmitted orthogonal amplitude modulation signals.

[0074] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

[0075] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems) and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

Claims

1. A method for generating and detecting a probability-shaped orthogonal amplitude signal, characterized in that: The specific steps include: Determine the high-order modulated QAM signal to be sent by the transmitter, and determine and truncate the constellation points with the highest bit error rate; Re-allocate the MB probability of the remaining constellation points after truncation to obtain the transmission probability of all transmitted orthogonal amplitude modulation signals; Based on the original orthogonal amplitude signal receiving method, the receiving end receives the orthogonal amplitude modulated signal after probability shaping; The remaining constellation points after truncation are re-allocated with MB probability according to the required spectrum utilization, wherein the transmission probability of each constellation point after allocation is: in, Indicates the The transmission probability of a constellation point, Indicates the set of constellation points that need to be sent. Indicates the degree of probability shaping, represents the exponential function with the natural constant e as the base, Indicates taking Real function, Indicates taking Imaginary part function.

2. The method for generating and detecting a probability-shaped orthogonal amplitude signal according to claim 1, wherein: The specific steps of determining and truncating the constellation point with a large bit error rate include: Determine the constellation point with the largest bit error rate based on the result obtained by sending feedback of the probability coded signal; The constellation points with a large bit error rate are truncated.

3. The method for generating and detecting a probability-shaped orthogonal amplitude signal according to claim 1, wherein: The MB probability distribution of the remaining constellation points after truncation is performed again to obtain the transmission probability of all transmitted quadrature amplitude modulation signals. The specific steps include: The remaining constellation points after truncation are re-allocated with MB probability according to the required spectrum utilization, so as to obtain the transmission probabilities of all transmitted orthogonal amplitude modulation signals.

4. The method for generating and detecting a probability-shaped orthogonal amplitude signal according to claim 1, wherein: The receiving end receives the quadrature amplitude modulated signal after probability shaping based on the original quadrature amplitude signal receiving mode, and the specific steps include: At the receiving end, dispersion compensation, signal synchronization, channel compensation, frequency offset and phase compensation, bit mapping and error calculation are performed on the orthogonal amplitude modulation signal after probability shaping to achieve reception of the orthogonal amplitude modulation signal after probability shaping.

5. The method for generating and detecting a probability-shaped orthogonal amplitude signal according to claim 4, wherein: The signal synchronization is used to find the corresponding transmission data frame; The channel compensation is used to reduce the distortion introduced by channel damage; The channel compensation includes linear compensation and nonlinear compensation.

6. The method for generating and detecting a probability-shaped orthogonal amplitude signal according to claim 4, wherein: The frequency offset phase compensation is used to compensate for the frequency difference and phase difference between the local oscillator laser and the transmitted carrier; The bit mapping is used to restore the orthogonal amplitude signal to a bit signal.

7. A probability-shaped orthogonal amplitude signal generation and detection system, characterized in that: include: A determination module is used to determine the high-order modulated QAM signal to be sent by the transmitter, and to determine and truncate the constellation point with a large bit error rate; An allocation module, which is used to re-allocate the MB probabilities of the remaining constellation points after truncation to obtain the transmission probabilities of all transmitted orthogonal amplitude modulation signals; A receiving module, which is used to receive the quadrature amplitude modulated signal after probability shaping at the receiving end based on the original quadrature amplitude signal receiving method; The remaining constellation points after truncation are re-allocated with MB probability according to the required spectrum utilization, wherein the transmission probability of each constellation point after allocation is: in, Indicates the The transmission probability of a constellation point, Indicates the set of constellation points that need to be sent. Indicates the degree of probability shaping, represents the exponential function with the natural constant e as the base, Indicates taking Real function, Indicates taking Imaginary part function.

8. A probability-shaped orthogonal amplitude signal generation and detection system as claimed in claim 7, characterized in that: The specific process of determining and truncating the constellation point with a large bit error rate includes: Determine the constellation point with the largest bit error rate based on the result obtained by sending feedback of the probability coded signal; The constellation points with a large bit error rate are truncated.

9. The probability-shaped orthogonal amplitude signal generation and detection system according to claim 7, characterized in that: The MB probability distribution is performed again on the remaining constellation points after truncation to obtain the transmission probability of all transmitted orthogonal amplitude modulation signals. The specific process includes: The remaining constellation points after truncation are re-allocated with MB probability according to the required spectrum utilization, so as to obtain the transmission probabilities of all transmitted orthogonal amplitude modulation signals.

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