A method and device for suppressing peak-to-average ratio of digital multi-carrier system

Abstract

A method and device for suppressing a peak-to-average ratio (PAR) of a digital multi-carrier system relates to the field of optical communication technology. The PAR suppression method includes: defining a frequency interval set based on the bandwidth of each subcarrier signal in a digital multi-carrier DMB signal; obtaining clipping noise of the DMB signal, filtering the signal based on the frequency interval set and the clipping noise to obtain a peak suppression signal, superimposing the signal on the DMB signal to suppress the PAR, and obtaining the suppressed DMB signal. The PAR suppression method and device of the present application, while suppressing the PAR of the digital multi-carrier signal, ensure that the subcarrier signal is not damaged and can be independently received and demodulated, thereby improving the performance of the digital multi-carrier optical transmission system. The present application solves the problem of limited efficiency and output power of the power amplifier and modulator in the transmitter of the digital multi-carrier system due to high PAPR, thereby increasing the transmission distance and coverage range.

Description

Technical Field

[0001] The present application relates to the field of optical communication technology, and in particular to a method and device for suppressing peak-to-average ratio of a digital multi-carrier system. Background Art

[0002] With the rapid development of technologies such as edge computing and the Internet of Things, the demand for high-speed point-to-multipoint optical networks is becoming increasingly urgent. These networks need to be able to meet diverse user needs and flexibly upload and download information.

[0003] Among related technologies, Digital Multiband (DMB) technology is widely used because it can independently modulate multiple subcarriers at the electrical layer of the transmitting end, independently receive a single subcarrier at the receiving end, and has high dispersion tolerance and resistance to optical fiber nonlinearity.

[0004] However, DMB technology, like Orthogonal Frequency Division Multiplexing (OFDM), faces the challenge of high Peak to Average Power Ratio (PAPR). High PAPR means high input power back-off for the transmitter's power amplifier—when the PA's output power is very low, the peak voltage reaches the linear region limit. For the optical modulator, high PAPR means low average modulation depth and low output optical power. Therefore, high PAPR directly limits the operating efficiency of the transmitter's power amplifier and restricts the modulator's output optical power, which in turn limits the transmission distance and bit error rate of the optical transmission system. Summary of the Invention

[0005] The present application provides a method and device for peak-to-average ratio suppression of a digital multi-carrier system, which can solve the technical problem in the prior art of limited working efficiency and output power due to a high peak-to-average ratio.

[0006] In a first aspect, the present application provides a method for peak-to-average ratio suppression in a digital multi-carrier system, the method comprising:

[0007] A frequency interval set is defined according to the bandwidth of each subcarrier signal in the digital multicarrier DMB signal;

[0008] The clipping noise of the DMB signal is obtained, and filtered according to the frequency interval set and the clipping noise to obtain a peak suppression signal, which is superimposed on the DMB signal to suppress the peak-to-average ratio and obtain a suppressed DMB signal.

[0009] In conjunction with the first aspect, in one embodiment, after defining the frequency interval set, the method further includes setting a target peak-to-average ratio and an iteration number threshold;

[0010] After obtaining the suppressed DMB signal, the method further includes:

[0011] Calculate the peak-to-average ratio after suppression, and when the peak-to-average ratio after suppression is greater than the target peak-to-average ratio, obtain the clipping noise of the suppressed DMB signal, until the new suppressed peak-to-average ratio is no greater than the target peak-to-average ratio or the number of peak-to-average ratio suppression iterations exceeds an iteration number threshold, and output the new suppressed DMB signal.

[0012] In combination with the first aspect, in one embodiment, a plurality of target peak-to-average ratios are provided, and each target peak-to-average ratio corresponds to a new suppressed DMB signal; and the method further includes:

[0013] The corresponding relationship between the target peak-to-average ratio and the new suppressed peak-to-average ratio is obtained to obtain the optimal target peak-to-average ratio, and then the corresponding optimally suppressed DMB signal is output.

[0014] In combination with the first aspect, in one embodiment, before setting the target peak-to-average ratio, the method further includes: calculating an initial peak-to-average ratio of the DMB signal;

[0015] The multiple target peak-to-average ratios are obtained by: decreasing the initial peak-to-average ratio by a preset step size;

[0016] The above preset step size is 0.1dB to 0.5dB.

[0017] In combination with the first aspect, in one embodiment, when the preset step size is less than or equal to 0.3 dB, as the target peak-to-average ratio decreases, the inflection point where the suppressed peak-to-average ratio changes from decreasing to increasing is the optimal target peak-to-average ratio;

[0018] When the preset step size is greater than 0.3 dB, and the difference between two adjacent suppressed peak-to-average ratios is less than the preset step size, the current target peak-to-average ratio is the optimal target peak-to-average ratio.

[0019] In combination with the first aspect, in one embodiment, before obtaining the clipping noise of the DMB signal, the method further includes:

[0020] Set the clipping threshold according to the target peak-to-average ratio;

[0021] The clipping noise is generated by clipping the DMB signal exceeding a preset clipping threshold.

[0022] In conjunction with the first aspect, in one embodiment, before being superimposed on the DMB signal, the method further includes:

[0023] performing weighted least squares estimation using the clipping noise and the peak suppression signal to determine an optimal weighting factor of the peak suppression signal;

[0024] According to the above optimal weighting factor, the peak suppression signal is weightedly corrected.

[0025] In combination with the first aspect, in one implementation, the frequency interval set I is:

[0026]

[0027] Where N is half of the total number of carriers, B s is the bandwidth of the subcarrier signal, and B0 is the bandwidth of the frequency interval.

[0028] In combination with the first aspect, in one embodiment, after obtaining the clipping noise of the DMB signal, the method further includes: performing a fast Fourier transform on the clipping noise to convert it into frequency domain noise;

[0029] After obtaining the peak suppression signal, the method further includes: performing an inverse fast Fourier transform on the peak suppression signal to obtain a time domain signal.

[0030] In a second aspect, the present application provides a peak-to-average ratio suppression device for a digital multi-carrier system, the device comprising:

[0031] A definition module, which is used to define a frequency interval set according to the bandwidth of each subcarrier signal in the digital multicarrier DMB signal;

[0032] The suppression module is used to obtain the clipping noise of the DMB signal, filter it according to the frequency interval set and the clipping noise, obtain a peak suppression signal, and add it to the DMB signal to suppress the peak-to-average ratio to obtain the suppressed DMB signal.

[0033] The beneficial effects of the technical solutions provided in the embodiments of the present application include:

[0034] By defining a frequency interval set based on the bandwidth of each subcarrier signal in a digital multicarrier DMB signal; then obtaining the clipping noise of the DMB signal, and filtering it according to the frequency interval set and the clipping noise to obtain a peak suppression signal, and then superimposing the peak suppression signal on the DMB signal to suppress the peak-to-average ratio to obtain a suppressed DMB signal; while suppressing the peak-to-average ratio of the digital multicarrier signal, it ensures that the subcarrier signal is not damaged and can be independently received and demodulated, so as to improve the performance of the digital multicarrier optical transmission system, and solve the problem of limited efficiency and output power of the power amplifier and modulator in the digital multicarrier system transmitter due to high PAPR, thereby increasing the transmission distance and coverage range. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of an embodiment of a peak-to-average ratio suppression method of the present application;

[0036] Figure 2 This is a flow chart of another embodiment of the peak-to-average ratio suppression method of the present application;

[0037] Figure 3 This is a flow chart of the transmission link and signal processing at the transceiver end according to an embodiment of the present application;

[0038] Figure 4 A curve diagram showing the corresponding relationship between the target peak-to-average ratio and the newly suppressed peak-to-average ratio according to an embodiment of the present application;

[0039] Figure 5 A comparison diagram of the peak-to-average ratio complementary cumulative distribution function (CCDF) of the embodiment of the present application and the case without PAPR suppression;

[0040] Figure 6 This is a comparison chart of the transmission performance of the system bit error rate-link loss in the embodiment of the present application and without PAPR suppression;

[0041] Figure 7 This is a functional module diagram of an embodiment of a peak-to-average ratio suppression device of the present application. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] In a first aspect, an embodiment of the present application provides a method for peak-to-average ratio suppression in a digital multi-carrier system.

[0044] In one embodiment, referring to Figure 1 , Figure 1 This is a flow chart of an embodiment of the peak-to-average ratio suppression method of the present application. Figure 1 As shown, the peak-to-average ratio suppression method includes the steps of:

[0045] S1 based on the bandwidth of each subcarrier signal in the digital multi-carrier DMB signal, define the frequency interval set;

[0046] S2. Obtain clipping noise of the DMB signal, and filter it according to the frequency interval set and the clipping noise to obtain a peak suppression signal, which is superimposed on the DMB signal to suppress the peak-to-average ratio, and obtain a suppressed DMB signal.

[0047] In this embodiment, a frequency interval set is defined according to the bandwidth of each subcarrier signal in a digital multicarrier DMB signal; then, the clipping noise of the DMB signal is obtained, and filtered according to the frequency interval set and the clipping noise to obtain a peak suppression signal, and then the peak suppression signal is superimposed on the DMB signal to suppress the peak-to-average ratio to obtain a suppressed DMB signal; while suppressing the peak-to-average ratio of the digital multicarrier signal, it is ensured that the subcarrier signal is not damaged and can be independently received and demodulated, so as to improve the performance of the digital multicarrier optical transmission system. This application solves the problem of limited efficiency and limited output power of the power amplifier and modulator in the transmitter of the digital multicarrier system due to high PAPR, thereby increasing the transmission distance and coverage range.

[0048] Based on the above embodiment, in this embodiment, in the above step 1, after defining the frequency interval set, it further includes setting a target peak-to-average ratio and an iteration number threshold.

[0049] In the above step 2, after obtaining the suppressed DMB signal, the method further includes: calculating the suppressed peak-to-average ratio, and then comparing the suppressed peak-to-average ratio with a target peak-to-average ratio.

[0050] When the suppressed peak-to-average ratio is greater than the target peak-to-average ratio, the clipping noise of the suppressed DMB signal is obtained, and a new peak suppression signal is obtained, which is superimposed on the suppressed DMB signal to perform peak-to-average ratio suppression to obtain a new suppressed DMB signal, and then the new suppressed peak-to-average ratio is calculated until the new suppressed peak-to-average ratio is no greater than the target peak-to-average ratio or the number of peak-to-average ratio suppression iterations exceeds an iteration number threshold. At this time, the new suppressed DMB signal is output.

[0051] When the suppressed peak-to-average ratio is less than or equal to the target peak-to-average ratio, the suppressed DMB signal is directly output.

[0052] In this embodiment, by setting the target peak-to-average ratio and the iteration number threshold, the effect of suppressing the signal peak-to-average ratio can be further improved.

[0053] Furthermore, in one embodiment, a plurality of target peak-to-average ratios are provided, and each target peak-to-average ratio corresponds to a new suppressed DMB signal, that is, each target peak-to-average ratio corresponds to a new suppressed peak-to-average ratio.

[0054] The peak-to-average ratio suppression method further includes:

[0055] The corresponding relationship between the target peak-to-average ratio and the new suppressed peak-to-average ratio is obtained, and the optimal target peak-to-average ratio is obtained according to the corresponding relationship, and then the optimally suppressed DMB signal corresponding to the target peak-to-average ratio is output.

[0056] In this embodiment, multiple target peak-to-average ratios are set to accelerate the determination of the optimal target peak-to-average ratio, ensure the peak-to-average ratio suppression effect, and solve the problem of unreasonable target peak-to-average ratio setting.

[0057] Furthermore, in one embodiment, before setting the target peak-to-average ratio, the method further includes: calculating an initial peak-to-average ratio of the DMB signal.

[0058] It is understood that the Peak to Average Power Ratio (PAPR) is the ratio between the peak power and the average power of a signal, and is used to measure the degree of fluctuation of the signal power.

[0059] The initial peak-to-average power ratio is the ratio between the peak power and the average power of the original DMB signal.

[0060] In this embodiment, the multiple target peak-to-average ratios are obtained by: decreasing the initial peak-to-average ratio by a preset step size;

[0061] The above preset step size is 0.1dB to 0.5dB.

[0062] Optionally, when a computer CPU (Central Processing Unit) is used for digital signal processing in an offline signal transmission scenario, the multiple target peak-to-average ratios are obtained by: decreasing the initial peak-to-average ratio in 0.1 dB steps.

[0063] When using a CPU equipped with an FPGA (Field Programmable Gate Array) or other CPU with insufficient computing power for digital signal processing scenarios with real-time signal transmission, multiple target peak-to-average ratios are obtained by decreasing the initial peak-to-average ratio in 0.5dB steps.

[0064] In this embodiment, different scenario requirements can be adjusted according to network needs to set different target peak-to-average ratios to meet diverse application scenarios and have high adaptability.

[0065] Furthermore, based on the corresponding relationship between the target peak-to-average ratio and the new suppressed peak-to-average ratio, the optimal target peak-to-average ratio is obtained, specifically including:

[0066] When the preset step size is less than or equal to 0.3dB, as the target peak-to-average ratio decreases, the inflection point where the suppressed peak-to-average ratio changes from decreasing to increasing is the optimal target peak-to-average ratio;

[0067] When the preset step size is greater than 0.3 dB, and the difference between two adjacent suppressed peak-to-average ratios is less than the preset step size, the current target peak-to-average ratio is the optimal target peak-to-average ratio.

[0068] Optionally, when the preset step size is 0.5 dB, when the difference between two adjacent suppressed peak-to-average ratios is less than 0.5 dB, the current target peak-to-average ratio is the optimal target peak-to-average ratio.

[0069] When the difference between two adjacent suppressed peak-to-average ratios is less than 0.5 dB, the current target peak-to-average ratio is the smaller of the two.

[0070] In this embodiment, different scenarios require different ways of obtaining the optimal target peak-to-average ratio, which can effectively adapt to the hardware complexity requirements of different systems and avoid the problem of inaccurate optimal target peak-to-average ratio acquisition caused by a single setting method.

[0071] Furthermore, in one embodiment, before obtaining the clipping noise of the DMB signal in the step S2, the method further includes: setting a clipping threshold according to a target peak-to-average ratio.

[0072] The clipping noise is generated by clipping a DMB signal exceeding a preset clipping threshold.

[0073] In this embodiment, the clipping threshold A is:

[0074]

[0075] Among them, the target PAPR is the target peak-to-average ratio, is the average power.

[0076] In this embodiment, each target peak-to-average ratio corresponds to a clipping threshold, and by setting corresponding clipping thresholds for different target peak-to-average ratios, the efficiency of clipping processing can be effectively improved.

[0077] Furthermore, in one embodiment, before superimposing the peak suppression signal onto the DMB signal, the method further includes:

[0078] First, performing weighted least squares estimation using the clipping noise and the peak suppression signal to determine an optimal weighting factor of the peak suppression signal;

[0079] Then, the peak suppression signal is weighted and corrected according to the above optimal weighting factor.

[0080] Subsequently, the corrected peak suppression signal may be superimposed on the DMB signal to perform peak-to-average ratio suppression.

[0081] In this embodiment, the filtering process makes the power of the peak-suppressed signal lower than the clipping noise. Therefore, the peak-suppressed signal needs to be corrected to accelerate the iterative convergence process. By optimizing the peak-suppressed signal using weighted estimation and the least-squares method, the error between the clipping noise and the peak-suppressed signal is effectively reduced. This error minimization mechanism ensures the effectiveness of PAPR suppression, accelerates the iterative process, and effectively reduces computational complexity.

[0082] Furthermore, the above-mentioned DMB signal includes a plurality of symmetrically distributed subcarriers, that is, the plurality of subcarriers are symmetrically distributed about a central carrier. After determining the bandwidth of each subcarrier, a frequency interval set can be defined.

[0083] The above frequency interval set I is:

[0084]

[0085] Where N is half of the total number of carriers, B s is the bandwidth of the subcarrier signal, B0 is the bandwidth of the frequency interval, and the frequencies belonging to any domain in this set are in the frequency interval.

[0086] Furthermore, in one embodiment, after obtaining the clipping noise of the DMB signal in the step S2, the method further includes: performing a fast Fourier transform on the clipping noise to convert it into frequency domain noise.

[0087] In this embodiment, the clipping noise is converted into frequency domain noise by performing fast Fourier transform, so that the clipping noise and the bandpass filter are subsequently filtered using the frequency domain product to obtain a peak suppression signal.

[0088] Furthermore, in one embodiment, after obtaining the peak suppression signal in the above step S2, the method further includes: performing an inverse fast Fourier transform on the peak suppression signal to obtain a time domain signal.

[0089] In this embodiment, the peak suppression signal is converted back into a time domain signal by performing an inverse fast Fourier transform, which facilitates subsequent correction and superposition operations to obtain a suppressed DMB signal.

[0090] Understandably, in OFDM (Orthogonal Frequency Division Multiplexing) systems, clipping can be used to reduce PAPR, but this can lead to signal degradation and increased bit error rates. Furthermore, techniques such as partial transmission sequencing and selective mapping are also widely used in OFDM. These techniques reduce PAPR by increasing redundancy, but they require information about all subcarriers for signal recovery, making them unsuitable for digital multicarrier systems that independently receive subcarriers.

[0091] This embodiment's peak-to-average ratio (PAPR) suppression method is applicable to digital signal processing within the transmitter electrical signal layer. It segments the signal spectrum into segments and injects a time-frequency domain joint peak suppression signal at frequency intervals. This effectively reduces the signal's PAPR while avoiding distortion caused by signal clipping, maintaining data signal integrity and transmission performance. Furthermore, the receiving end requires no additional information and allows for independent subcarrier reception, making this method suitable for flexible point-to-multipoint network configurations.

[0092] like Figure 2 As shown, the peak-to-average ratio suppression method of this embodiment includes:

[0093] A1. Generation of digital multi-carrier DMB signals: Figure 3 As shown in the figure, multiple subcarrier bit streams are input in parallel, undergo 16QAM (Quadrature Amplitude Modulation) mapping, 2x upsampling, raised cosine filtering, and upconversion before being combined to generate a DMB signal as input. The multiple subcarriers are 16, and each has a bit length of 40,320.

[0094] A2. PAPR suppression initialization configuration: In this example, the total number of carriers is 16, N is half of the total number of carriers, N = 8, the bandwidth of the frequency interval B0 is set to 200MHz, and the bandwidth of the subcarrier signal B s is 3.6GHz. Substituting the parameters into the frequency interval set I, we can get the expression:

[0095]

[0096] A3. Calculate the initial PAPR of the initial DMB signal. The PAPR calculation formula is:

[0097]

[0098] Where, x(n) is the DMB signal, max[|x(n)| 2 ] is the peak power, is the average power.

[0099] A4. Clipping and calculation of clipping noise: where the clipping threshold A is set according to the target PAPR.

[0100] During the clipping process, the signal points with a modulus greater than the clipping threshold are clipped to the clipping threshold and the phase is retained. The remaining signal points remain unchanged to generate the clipped signal. The clipped signal is then subtracted from the pre-clipping signal to obtain the clipping noise. The calculation method is expressed as:

[0101] f(n)=xclip (n)-x k (n)

[0102]

[0103] in, Represents a complex number with a modulus of A and an amplitude of X k (n).

[0104] Then, the clipping noise is transformed into the frequency domain by fast Fourier transform, and the calculation is expressed as:

[0105] F(k)=FFT(f(n))

[0106] Where f(n) is the clipping noise; x k (n) is the DMB signal in the nth iteration, and x1(n)=x(n).

[0107] A5. Design a bandpass filter H(k) based on the above frequency interval set. The filter only retains the clipping noise that exists in the frequency interval band and filters out the clipping noise that exists in the signal band, thus preventing the signal from being interfered with by the clipping noise. The calculation method for bandpass filter design is:

[0108]

[0109] Among them, i is the frequency interval number, k is the frequency parameter, To express "existence", Indicates "any". i Denotes the i-th set in I. In this embodiment, for frequency k in the frequency response H(k), if there exists i such that k belongs to the set I i , then the frequency response at k is 1. If for any i, k does not belong to I i , then the frequency response at k is 0.

[0110] The peak suppression signal C(k) in the frequency domain is obtained by filtering the clipping noise and the bandpass filter using the frequency domain product, which is calculated as follows:

[0111] C(k) = F(k) H(k) Then, the peak suppressed signal is converted back to the time domain using the inverse fast Fourier transform:

[0112] c(n)=IFFT(C(k))

[0113] A6. To compensate for the power loss of the clipping noise caused by the filtering operation, the optimal weighting factor of the peak suppression signal is estimated using the least squares method. Specifically, the weighting coefficient of the peak suppression signal and the clipping noise is calculated. The optimal weighting factor is determined using the least squares estimation method. The optimal weighting factor is calculated as follows:

[0114]

[0115] Where Z is a set of integers.

[0116] A7. Multiply the optimal weighting factor calculated in step A6 by the peak suppression signal and add the result to the pre-clipping signal to obtain the digital multi-carrier signal after peak-to-average ratio suppression. The calculation method is as follows:

[0117]

[0118] A8. Calculate the suppressed DMB signal X k+1 The PAPR of (n) is calculated in the same manner as in A3. It is determined whether the number of PAPR suppression iterations exceeds the iteration threshold. In this embodiment, the iteration threshold is set to 50.

[0119] If the number of iterations exceeds the iteration number threshold, the signal after the peak-to-average ratio suppression is directly output. If it does not exceed, the peak-to-average ratio after this iteration is judged to be greater than the target peak-to-average ratio. If it is less than or equal to the target peak-to-average ratio, the calculation ends and the signal after the peak-to-average ratio suppression is output. If it is still greater than the target peak-to-average ratio, it is used as the input signal for the next iterative calculation and enters the next iteration. The operations in A4-A8 are repeated until the peak-to-average ratio is less than or equal to the target peak-to-average ratio or exceeds the set iteration number threshold, and the suppressed DMB signal corresponding to this target peak-to-average ratio is obtained.

[0120] Preferably, multiple target peak-to-average ratios may be set, and the suppression process of steps A1 to A7 is repeated each time a target peak-to-average ratio is set.

[0121] In this embodiment, only the target peak-to-average ratio setting is changed each time and scanning is performed with a certain step size to obtain the relationship between the reduced PAPR value and the target PAPR to obtain the optimal target PAPR setting value.

[0122] Optionally, for scenarios with low hardware requirements, starting from the initial PAPR, the target PAPR is scanned in a decreasing step size of 0.1dB. When entering the excessive suppression area (that is, as the target value decreases, the suppression effect becomes worse), the inflection point is taken as the optimal target PAPR; for scenarios with high hardware requirements, it is necessary to reduce the algorithm complexity. Starting from the initial PAPR, the target PAPR is scanned in a decreasing step size of 0.5dB. When the difference in the PAPR values ​​after the adjacent scanning points is less than 0.5dB, it indicates that the saturation suppression area has been entered. The target PAPR value at this time is taken as the optimal target PAPR.

[0123] like Figure 4As shown, in the target PAPR optimization and selection process of this embodiment, the hardware complexity requirement is relatively low. Therefore, when scanning and selecting the optimal target PAPR, starting from the initial PAPR, the target PAPR is scanned in a decreasing step size of 0.1 dB. The relationship curve between the reduced PAPR, i.e., the new suppressed peak-to-average ratio, and the target PAPR is obtained and analyzed. The analysis can be divided into the following parts:

[0124] Unsuppressed area: target PAPR>=initial PAPR, no suppression effect.

[0125] Linear suppression region: Target PAPR = PAPR after suppression. The frequency interval capacity is sufficient to accommodate the peak suppression signal, and the PAPR after suppression can reach the target PAPR.

[0126] Saturation suppression region: The frequency interval is insufficient to completely accommodate the peak suppression signal. The PAPR after suppression is higher than the target PAPR, but decreases as the target PAPR decreases.

[0127] Over-suppression area: The target PAPR is set too low, and the PAPR after suppression increases as the target PAPR decreases.

[0128] The optimal target PAPR appears at the inflection point between the saturation suppression region and the excessive suppression region. Therefore, the optimal target PAPR is 4.3 dB. The final PAPR suppression signal is obtained when the target PAPR is set to the optimal target PAPR.

[0129] In this embodiment, since the peak-to-average ratio of digital multi-carrier is data-dependent, the above process is repeated multiple times to calculate the complementary cumulative distribution function without and with PAPR suppression. The number of repetitions is set to 10,000, and the bit stream data is randomly generated each time.

[0130] like Figure 5 The complementary cumulative distribution function statistics shown are generally compared with CCDF=10 -3 It can be seen that the use of PAPR suppression effectively reduces the peak-to-average ratio.

[0131] like Figure 3 As shown in the figure, the digital multi-carrier signal after PAPR suppression is input into the optical fiber link for transmission, and the bit error rate is tested. The experimental link part includes coherent optical signal transmission, optical fiber link transmission, and coherent optical reception. Among them, the optical fiber link part includes an optical amplifier, G652 single-mode optical fiber, and an optical attenuator. The signal processing part at the receiving end includes frequency offset compensation, linear equalization, phase recovery, and bit error calculation. Figure 6 As shown in Figure 2, a comparison of the optical transmission bit error rate with and without PAPR suppression is performed. It can be seen that under the same link loss conditions, PAPR suppression reduces the bit error rate and can improve the performance of digital multi-carrier optical transmission.

[0132] The method of this embodiment segments and slices the spectrum of a digital multi-carrier signal, injects a time-frequency domain joint peak suppression signal through frequency intervals, effectively reduces the PAPR of the signal, and generates a peak suppression signal by using iterative calculation based on least squares estimation. This method can not only be flexibly applied to peak-to-average ratio suppression of various digital multi-carrier systems with different numbers of subcarriers, point-to-point, and point-to-multipoint, but also ensures that the subcarrier signals are not damaged and can be independently received and demodulated while suppressing the peak-to-average ratio of the digital multi-carrier signal, thereby improving the performance of the digital multi-carrier optical transmission system.

[0133] In a second aspect, an embodiment of the present application further provides a peak-to-average ratio suppression device for a digital multi-carrier system.

[0134] In one embodiment, referring to Figure 7 , Figure 7 This is a functional module diagram of an embodiment of a peak-to-average ratio suppression device of the present application. Figure 7 As shown, the peak-to-average ratio suppression device includes a definition module and a suppression module.

[0135] The above definition module is used to define a frequency interval set according to the bandwidth of each subcarrier signal in the digital multicarrier DMB signal.

[0136] The suppression module is used to obtain the clipping noise of the DMB signal, and filter it according to the frequency interval set and the clipping noise to obtain a peak suppression signal, and superimpose it on the DMB signal to suppress the peak-to-average ratio to obtain the suppressed DMB signal.

[0137] Furthermore, in one embodiment, the peak-to-average ratio suppression device further includes a setting module, and the setting module is used to set a target peak-to-average ratio and a threshold of the number of iterations.

[0138] The suppression module is further configured to calculate the suppressed peak-to-average ratio after obtaining the suppressed DMB signal, and when the suppressed peak-to-average ratio is greater than the target peak-to-average ratio, obtain the clipping noise of the suppressed DMB signal, until the new suppressed peak-to-average ratio is no greater than the target peak-to-average ratio or the number of peak-to-average ratio suppression iterations exceeds an iteration number threshold, and then output the new suppressed DMB signal.

[0139] Furthermore, in one embodiment, the setting module is used to set multiple target peak-to-average ratios. Therefore, each target peak-to-average ratio corresponds to a new suppressed DMB signal.

[0140] The suppression module is further configured to obtain a corresponding relationship between the target peak-to-average ratio and the new suppressed peak-to-average ratio, derive an optimal target peak-to-average ratio, and output a corresponding optimally suppressed DMB signal.

[0141] Furthermore, in one embodiment, the peak-to-average ratio suppression device further includes a calculation module, which is used to calculate the initial peak-to-average ratio of the DMB signal.

[0142] The setting module is used to set multiple target peak-to-average ratios respectively: the initial peak-to-average ratio is obtained by decreasing it in a preset step size; the preset step size is 0.1dB to 0.5dB.

[0143] Furthermore, in one embodiment, the suppression module is further configured to:

[0144] When the preset step size is less than or equal to 0.3dB, as the target peak-to-average ratio decreases, the inflection point where the suppressed peak-to-average ratio changes from decreasing to increasing is the optimal target peak-to-average ratio;

[0145] When the preset step size is greater than 0.3 dB, and the difference between two adjacent suppressed peak-to-average ratios is less than the preset step size, the current target peak-to-average ratio is the optimal target peak-to-average ratio.

[0146] Furthermore, in one embodiment, the setting module is further configured to set a clipping threshold according to a target peak-to-average ratio. The clipping noise is generated by clipping a DMB signal exceeding a preset clipping threshold.

[0147] Furthermore, in one embodiment, the suppression module is further configured to:

[0148] performing weighted least squares estimation using the clipping noise and the peak suppression signal to determine an optimal weighting factor of the peak suppression signal;

[0149] According to the above optimal weighting factor, the peak suppression signal is weightedly corrected.

[0150] Furthermore, in one embodiment, the peak-to-average ratio suppression device further includes a conversion module, which is used to perform fast Fourier transform on the clipping noise to convert it into frequency domain noise; the conversion module is also used to perform inverse fast Fourier transform on the peak suppression signal to obtain a time domain signal.

[0151] Among them, the functional implementation of each module in the above-mentioned peak-to-average ratio suppression device corresponds to the various steps in the above-mentioned peak-to-average ratio suppression method embodiment, and their functions and implementation processes will not be repeated here one by one.

[0152] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0153] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit the "first", "second" and "third" to different types.

[0154] In the description of the embodiments of this application, the words "exemplary," "for example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "for example," or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[0155] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0156] In some processes described in the embodiments of the present application, multiple operations or steps are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed in sequence or in parallel, and these operations or steps may be combined.

[0157] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling a terminal device to execute the methods described in each embodiment of the present application.

[0158] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for peak-to-average ratio suppression in a digital multi-carrier system, characterized in that: The method comprises: A frequency interval set is defined according to the bandwidth of each subcarrier signal in the digital multicarrier DMB signal; Obtaining clipping noise of the DMB signal, filtering it according to the frequency interval set and the clipping noise to obtain a peak suppression signal, superimposing it on the DMB signal to perform peak-to-average ratio suppression, and obtaining a suppressed DMB signal; Filtering is performed according to the frequency interval set and the clipping noise to obtain a peak suppression signal, specifically comprising: designing a bandpass filter based on the set of frequency intervals, the filter retaining only clipping noise present within the frequency interval band; The clipping noise and the bandpass filter are filtered using a frequency domain product to obtain a peak suppressed signal in the frequency domain.

2. The peak-to-average ratio suppression method for a digital multi-carrier system according to claim 1, wherein: After defining the frequency interval set, it also includes setting the target peak-to-average ratio and the number of iterations threshold; After obtaining the suppressed DMB signal, the method further includes: Calculate the peak-to-average ratio after suppression, and when the peak-to-average ratio after suppression is greater than the target peak-to-average ratio, obtain the clipping noise of the suppressed DMB signal, until the new suppressed peak-to-average ratio is no greater than the target peak-to-average ratio or the number of peak-to-average ratio suppression iterations exceeds an iteration number threshold, and output the new suppressed DMB signal.

3. The peak-to-average ratio suppression method for a digital multi-carrier system according to claim 2, wherein: There are multiple target peak-to-average ratios, and each target peak-to-average ratio corresponds to a new suppressed DMB signal; the method further includes: The corresponding relationship between the target peak-to-average ratio and the new suppressed peak-to-average ratio is obtained to obtain the optimal target peak-to-average ratio, and then the corresponding optimally suppressed DMB signal is output.

4. The peak-to-average ratio suppression method for a digital multi-carrier system according to claim 3, wherein: Before setting the target peak-to-average ratio, the method further includes: calculating the initial peak-to-average ratio of the DMB signal; The multiple target peak-to-average ratios are obtained by: decreasing the initial peak-to-average ratio by a preset step size; The preset step size is 0.1dB~0.5dB.

5. The peak-to-average ratio suppression method for a digital multi-carrier system according to claim 4, wherein: When the preset step size is less than or equal to 0.3dB, as the target peak-to-average ratio decreases, the inflection point where the suppressed peak-to-average ratio changes from decreasing to increasing is the optimal target peak-to-average ratio; When the preset step size is greater than 0.3 dB, and the difference between two adjacent suppressed peak-to-average ratios is less than the preset step size, the current target peak-to-average ratio is the optimal target peak-to-average ratio.

6. The peak-to-average ratio suppression method for a digital multi-carrier system according to claim 1, wherein: Before obtaining the clipping noise of the DMB signal, the method further includes: Set the clipping threshold according to the target peak-to-average ratio; The clipping noise is generated by clipping the DMB signal exceeding a preset clipping threshold.

7. The peak-to-average ratio suppression method for a digital multi-carrier system according to claim 1, wherein: Before being superimposed on the DMB signal, the method further includes: performing weighted least squares estimation using the clipping noise and the peak suppression signal to determine an optimal weighting factor of the peak suppression signal; The peak suppression signal is weightedly modified according to the optimal weighting factor.

8. The peak-to-average ratio suppression method for a digital multi-carrier system according to claim 1, wherein: The frequency interval set I for: in, N is half of the total number of carriers, B s is the bandwidth of the subcarrier signal, B 0 is the bandwidth of the frequency interval.

9. The peak-to-average ratio suppression method for a digital multi-carrier system according to claim 1, wherein: After obtaining the clipping noise of the DMB signal, the method further includes: performing fast Fourier transform on the clipping noise to convert it into frequency domain noise; After obtaining the peak suppression signal, the method further includes: performing an inverse fast Fourier transform on the peak suppression signal to obtain a time domain signal.

10. A peak-to-average ratio suppression device for a digital multi-carrier system, characterized in that: The device comprises: A definition module, which is used to define a frequency interval set according to the bandwidth of each subcarrier signal in the digital multicarrier DMB signal; a suppression module, configured to obtain clipping noise of the DMB signal, filter the clipping noise according to the frequency interval set and the clipping noise to obtain a peak suppression signal, and superimpose the peak suppression signal on the DMB signal to perform peak-to-average ratio suppression to obtain a suppressed DMB signal; Filtering is performed according to the frequency interval set and the clipping noise to obtain a peak suppression signal, specifically comprising: designing a bandpass filter based on the set of frequency intervals, the filter retaining only clipping noise present within the frequency interval band; The clipping noise and the bandpass filter are filtered using a frequency domain product to obtain a peak suppressed signal in the frequency domain.

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