Peak-to-average power ratio suppression method and device for digital multicarrier system

Abstract

A peak-to-average power ratio suppression method and device for a digital multicarrier (DMB) system relate to the technical field of optical communication, and the peak-to-average power ratio suppression method comprises the following steps: defining a frequency interval set according to the bandwidth of each subcarrier signal in a digital multicarrier (DMB) signal; and acquiring clipping noise of the DMB signal, performing filtering according to the frequency interval set and the clipping noise to obtain a peak suppression signal, and superposing the peak suppression signal to the DMB signal to perform peak-to-average ratio suppression to obtain the suppressed DMB signal. According to the method and the device for suppressing the peak-to-average ratio, the peak-to-average ratio of the digital multi-carrier signal is suppressed, and meanwhile, the subcarrier signal is ensured not to be damaged and can be independently received and demodulated, so that the performance of a digital multi-carrier optical transmission system is improved; the problem that the efficiency and the output power of a power amplifier and a modulator in a digital multicarrier system transmitter are limited due to high PAPR is solved, so that the transmission distance and the coverage range can be increased.

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 the 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 the characteristics of high dispersion tolerance and resistance to optical fiber nonlinearity.

[0004] However, DMB technology, like Orthogonal Frequency Division Multiplexing (OFDM) technology, faces the challenge of high Peak to Average Power Ratio (PAPR). High PAPR means high input power back-off for the power amplifier in the transmitter - when the output power of the power amplifier is very low, the peak voltage has reached 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 working efficiency of the power amplifier in the transmitter and limits the optical power output by the modulator, 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 that the working efficiency and output power are limited due to a high peak-to-average ratio.

[0006] In a first aspect, the present application provides a peak-to-average ratio suppression method for 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 filtering is performed 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 the suppressed DMB signal is obtained.

[0009] In combination with the first aspect, in one implementation, 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] The suppressed peak-to-average ratio is calculated, and 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, until the new suppressed peak-to-average ratio is not greater than the target peak-to-average ratio or the number of peak-to-average ratio suppression iterations exceeds the iteration number threshold, and the new suppressed DMB signal is output.

[0012] In combination with the first aspect, in one implementation, the target peak-to-average ratio is set to be multiple, and each target peak-to-average ratio corresponds to a new suppressed DMB signal; 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 implementation, 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 implementation, 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, when 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 implementation manner, 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 combination with the first aspect, in one implementation manner, before being superimposed on the DMB signal, the method further includes:

[0023] Performing weighted least square 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 weighted and modified.

[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 implementation, 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 the peak suppression signal is obtained, 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 multi-carrier DMB signal;

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

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

[0034] By defining a frequency interval set according to the bandwidth of each subcarrier signal in a digital multicarrier DMB signal; then obtaining the clipping noise of the DMB signal, 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 the 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, and solve 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. 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 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 of the embodiment of the present application and the new suppressed peak-to-average ratio;

[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 A transmission performance comparison diagram of the system bit error rate-link loss in the embodiment of the present application and without PAPR suppression;

[0041] Figure 7 It 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 solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction 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. Based on the embodiments in the present application, 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 peak-to-average ratio suppression method for 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 comprises the steps of:

[0045] S1. Define a frequency interval set according to the bandwidth of each subcarrier signal in a digital multicarrier DMB signal;

[0046] S2. 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, which is superimposed on the DMB signal to suppress the peak-to-average ratio, and obtain the 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 the 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, and solve 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 also 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 a new suppressed peak-to-average ratio is calculated until the new suppressed peak-to-average ratio is not greater than the target peak-to-average ratio or the number of peak-to-average ratio suppression iterations exceeds an iteration number threshold, at which 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 the above 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 optimal 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 setting of the target peak-to-average ratio.

[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 can be 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 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 a digital signal processing scenario of offline signal transmission, a plurality of target peak-to-average ratios are respectively obtained by: decreasing the initial peak-to-average ratio in 0.1 dB steps.

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

[0064] In this embodiment, by different scenario requirements, it 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, according to 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, which specifically includes:

[0066] 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;

[0067] When the preset step size is greater than 0.3 dB, when 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 target peak-to-average ratios.

[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 acquisition of the optimal target peak-to-average ratio caused by a single setting method.

[0071] Furthermore, in one embodiment, in the above step S2, before obtaining the clipping noise of the above DMB signal, 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 value. By setting corresponding clipping threshold values ​​at different target peak-to-average ratios, the efficiency of clipping processing can be effectively improved.

[0077] Furthermore, in one embodiment, before the peak suppression signal is superimposed on the DMB signal, the method further includes:

[0078] Firstly, weighted least square estimation is performed using the clipping noise and the peak suppression signal to determine an optimal weighting factor of the peak suppression signal;

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

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

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

[0082] Furthermore, the above DMB signal includes a plurality of symmetrically distributed subcarriers, that is, the plurality of subcarriers are symmetrically distributed about the central carrier, and 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, in the step S2, 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.

[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 frequency domain product to obtain a peak suppression signal.

[0088] Furthermore, in one embodiment, in the above step S2, 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.

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

[0090] It is understandable that in OFDM (Orthogonal Frequency Division Multiplexing) systems, clipping can be used to reduce PAPR, but this will lead to signal degradation and increased bit error rate. In addition, partial transmission sequence and selective mapping techniques are also widely used in OFDM. These techniques reduce PAPR by increasing redundancy, but they need to know the information of all subcarriers to recover the signal, so such methods are not suitable for digital multi-carrier systems that receive subcarriers independently.

[0091] The peak-to-average ratio suppression method of this embodiment is applicable to the field of digital signal processing in the field of transmitter electrical signal layer technology. The signal spectrum is segmented and sliced, and the time-frequency domain joint peak suppression signal is injected through the frequency interval, which effectively reduces the PAPR of the signal while avoiding the distortion problem caused by signal clipping, and maintains the integrity and transmission performance of the data signal. In addition, the receiving end does not require additional information and allows independent reception of subcarriers, making this method also applicable to 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, the multi-channel sub-carrier bit stream data input is parallelly mapped by 16QAM (quadrature amplitude modulation), up-sampled by 2 times, filtered by raised cosine, and up-converted, and then combined to generate a DMB signal as input. Among them, the multi-channel sub-carrier is 16 channels, and the bit data length of each channel is 40320.

[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, where 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 whose modulus is greater than the clipping threshold are limited to the clipping threshold and the phase is retained. The other signal points remain unchanged to generate the clipped signal. Then, the difference between the clipped signal and the pre-clipping signal is taken 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 length of A and an amplitude angle 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 in the frequency interval band and filters out the clipping noise in the signal band to prevent the signal from being interfered by the clipping noise. The calculation method for bandpass filter design is:

[0108]

[0109] Where i is the frequency interval number, k is the frequency parameter, To express "existence", Indicates "any". i represents the i-th set in I. In this embodiment, for a 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. In order to compensate for the power loss caused by the above filtering operation to the clipping noise, the optimal weighting factor of the peak suppression signal is estimated by the least square method, that is, the weighting coefficient of the peak suppression signal and the clipping noise is calculated, and the optimal weighting factor is determined by the least square 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 signal before clipping to obtain the digital multi-carrier signal after the peak-to-average ratio is suppressed. 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 way as in A3. It is determined whether the number of PAPR suppression iterations exceeds the iteration number threshold. In this embodiment, the iteration number threshold is set to 50 times.

[0119] If the number of iterations exceeds the iteration number threshold, the signal after the peak-to-average ratio is directly output; if it does not exceed, it continues to determine whether the peak-to-average ratio after this iteration is 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 is suppressed 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, repeating the operations in A4-A8 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 the target peak-to-average ratio is obtained.

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

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

[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 decrease of 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 selection process of this embodiment, the hardware has a low requirement for complexity. Therefore, when scanning and selecting the optimal target PAPR, starting from the initial PAPR, the target PAPR is scanned in a decreasing step of 0.1 dB, and the relationship curve between the reduced PAPR, i.e., the new suppressed peak-to-average ratio, and the target PAPR is obtained and analyzed, which can be divided into the following parts:

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

[0125] Linear suppression area: 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 not sufficient 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 this time is 4.3 dB, and 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 PAPR suppression and with PAPR suppression. The number of repetitions is set to 10,000 times, 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, a 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 FIG. 1 , a comparison is made between the optical transmission bit error rate with and without PAPR suppression. It can be seen that the use of PAPR suppression under the same link loss condition 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. It 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, which can improve 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 FIG. 1 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 above-mentioned suppression module is also used 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 not greater than the target peak-to-average ratio or the number of peak-to-average ratio suppression iterations exceeds the iteration number threshold, and output the new suppressed DMB signal.

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

[0140] The suppression module is also used to obtain the corresponding relationship between the target peak-to-average ratio and the new suppressed peak-to-average ratio, obtain the optimal target peak-to-average ratio, and then output the corresponding optimal suppressed DMB signal.

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

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

[0143] Furthermore, in one embodiment, the above-mentioned suppression module is also used for:

[0144] 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;

[0145] When the preset step size is greater than 0.3 dB, when 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 used 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 above-mentioned suppression module is also used for:

[0148] Performing weighted least square 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 weighted and modified.

[0150] Furthermore, in one embodiment, the peak-to-average ratio suppression device further includes a conversion module, which is used to perform a fast Fourier transform on the clipping noise to convert it into frequency domain noise; the conversion module is also used to perform an 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 its 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 only for description 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 "first", "second" and "third" to different types.

[0154] In the description of the embodiments of the present application, "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 the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[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; the “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 that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed 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 a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially 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, disk, CD) as described above, and includes a number of instructions for 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 are not intended to 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 peak-to-average ratio suppression method for 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; The clipping noise of the DMB signal is obtained, and filtering is performed 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 the suppressed DMB signal is obtained.

2. The peak-to-average ratio suppression method for a digital multi-carrier system according to claim 1, characterized in that: 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: The suppressed peak-to-average ratio is calculated, and 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, until the new suppressed peak-to-average ratio is not greater than the target peak-to-average ratio or the number of peak-to-average ratio suppression iterations exceeds the iteration number threshold, and the new suppressed DMB signal is output.

3. The peak-to-average ratio suppression method for a digital multi-carrier system as claimed in claim 2, characterized in that: The target peak-to-average ratio is set to be multiple, 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 as claimed in claim 3, characterized in that: Before setting the target peak-to-average ratio, the method further includes: calculating an 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 to 0.5dB.

5. The peak-to-average ratio suppression method for a digital multi-carrier system as claimed in claim 4, characterized in that: 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; When the preset step size is greater than 0.3 dB, when 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, characterized in that: 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, characterized in that: Before being superimposed on the DMB signal, the method further comprises: Performing weighted least square 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 weighted and 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, characterized in that: The frequency interval set I is: 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.

9. The peak-to-average ratio suppression method of a digital multi-carrier system as claimed in claim 1, characterized in that: 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 the peak suppression signal is obtained, 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 multi-carrier DMB signal; 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, so as to obtain the suppressed DMB signal.

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