A method, device, equipment and medium for suppressing peak-to-average ratio of OFDM system

Abstract

The present application discloses a peak-to-average ratio suppression method, apparatus, device and medium for an OFDM system, and relates to the technical field of OFDM for mobile communication systems. The present application directly limits the time domain signal of the OFDM system, and improves the hyperbolic tangent function according to the appropriate compression coefficient set by the OFDM system during signal compression. At the same time, the improved hyperbolic tangent function is used to compress the sheared noise. Thanks to the continuous linear transformation of the hyperbolic tangent function, the nonlinear effect of the limiting operation on the signal is reduced, the bit error rate performance is enhanced, and the out-of-band distortion can be reduced.

Description

Technical Field

[0001] The present application relates to the field of OFDM technology for mobile communication systems, and in particular to a peak-to-average ratio suppression method, apparatus, device, and medium for an OFDM system. Background Art

[0002] Orthogonal Frequency Division Multiplexing (OFDM) is the basic physical layer modulation technology for the fourth-generation mobile communications (4G) and the fifth-generation mobile communications (5G). Its advantages, such as fast data transmission speed and high spectral efficiency, continue to make it widely used in various communication systems. However, one of the chronic problems of OFDM signals is its high Peak to Average Power Ratio (PAPR). This causes nonlinear distortion in nonlinear devices such as power amplifiers (PAs), increasing the system's bit error rate, and causing the device's power efficiency to decrease, increasing its energy consumption. Therefore, it is very important to suppress the PAPR of the widely used OFDM signals.

[0003] Currently, there are three commonly used peak-to-average power ratio suppression methods, namely probability-based technology, signal pre-distortion technology and coding technology; probability-based technology mainly includes selective mapping method (SLM) and partial transmission sequence method (PTS), which mainly reduces the peak-to-average power ratio (PAPR) by adjusting the signal; coding technology is to limit the set of signal code subsets that can be used for transmission. Only those codes with peak values ​​below the threshold can be selected for transmission, thereby avoiding signal peaks, but its codec is complex and computationally intensive, and is only applicable to cases where the number of subcarriers is relatively small; signal pre-distortion technology mainly includes limiting technology and compression and expansion technology, and its basic principle is to directly affect the peak-to-average power ratio of the signal by changing the amplitude of the transmitted signal.

[0004] The probability-based technologies, signal pre-distortion technologies, and coding technologies currently used are simple to implement and have good peak-to-average ratio (PAPR) suppression effects. However, these technologies are nonlinear transformations and will produce varying degrees of nonlinear distortion during signal processing, making it difficult to improve bit error rate performance. Summary of the Invention

[0005] The embodiments of the present application provide a peak-to-average ratio suppression method, apparatus, device, and medium for an OFDM system, which can solve the problem in the prior art that the current technology is a nonlinear transformation, which produces varying degrees of nonlinear distortion during signal processing, making it difficult to improve the bit error rate performance.

[0006] The present invention provides a method for suppressing peak-to-average ratio of an OFDM system, comprising the following steps:

[0007] An OFDM time domain signal of an OFDM system is obtained; a shearing operation is performed on the OFDM time domain signal to obtain a sheared signal, and shearing noise is obtained according to a difference between the time domain signal and the sheared signal;

[0008] Extracting a compression coefficient of a limiting noise compression function in a shear noise compression method CNC; multiplying an independent variable of a hyperbolic tangent function by the compression coefficient to form an improved independent variable; forming an improved hyperbolic tangent function based on the improved independent variable; using a ratio of the improved hyperbolic tangent function to the hyperbolic tangent function as an improved noise compression function; and forming an improved limiting noise compression function based on the improved noise compression function;

[0009] According to the improved limiting noise compression function and compression threshold, the shear noise is compressed while keeping the phase of the noise unchanged. The shear noise with a noise amplitude greater than the compression threshold is compressed once, while the shear noise with a noise amplitude less than the compression threshold remains unchanged, thus obtaining a compressed shear noise signal.

[0010] The compressed shear noise signal is added to the shear signal to obtain the OFDM time domain signal with peak-to-average ratio suppressed.

[0011] Preferably, after obtaining the shear noise, the method further includes performing denormalization on the shear noise to scale the shear noise, wherein the denormalization method is:

[0012] ;

[0013] in: represents shear noise; E [] indicates expectation.

[0014] Preferably, the acquisition of the improved noise compression function includes:

[0015] According to the noise compression coefficient, the shape of the compression function is controlled, and the hyperbolic tangent function is improved at the same time. The improved noise compression function is:

[0016] ;

[0017] in: represents the compression coefficient; tanh() represents the hyperbolic tangent function; x represents shearing noise.

[0018] Preferably, the improved limiting noise compression function is:

[0019] ;

[0020] in: Represents the original signal The average amplitude of represents the compression coefficient; tanh() represents the hyperbolic tangent function; represents the shear noise after denormalization; Indicates the phase of the noise signal.

[0021] Preferably, the method of adding and correcting the compressed shear noise signal and the shear signal to obtain the OFDM time domain signal after peak-to-average ratio suppression is:

[0022] ;

[0023] in: Indicates shear signal; represents the compressed shearing noise signal.

[0024] The embodiment of the present application further provides a peak-to-average ratio suppression device for an OFDM system, comprising:

[0025] The signal processing module is used to obtain an OFDM time domain signal of the OFDM system; perform a shearing operation on the OFDM time domain signal to obtain a sheared signal, and obtain shearing noise according to the difference between the time domain signal and the sheared signal;

[0026] A function module is used to extract a compression coefficient of a limiting noise compression function in a shear noise compression method CNC; multiply an independent variable of a hyperbolic tangent function by the compression coefficient to form an improved independent variable, form an improved hyperbolic tangent function based on the improved independent variable, use a ratio of the improved hyperbolic tangent function to the hyperbolic tangent function as an improved noise compression function, and form an improved limiting noise compression function based on the improved noise compression function;

[0027] A noise compression module is used to compress the shear noise according to the improved limiting noise compression function and the compression threshold value while keeping the phase of the noise unchanged. The shear noise with a noise amplitude greater than the compression threshold value is compressed once, and the shear noise with a noise amplitude less than the compression threshold value remains unchanged, thereby obtaining a compressed shear noise signal.

[0028] The suppression module is used to add and correct the compressed shear noise signal and the shear signal to obtain an OFDM time domain signal with a peak-to-average ratio suppressed.

[0029] An embodiment of the present application further provides an electronic device, including a memory and a processor;

[0030] The memory is used to store computer programs;

[0031] The processor is configured to implement the steps of the above-mentioned method for suppressing peak-to-average ratio of an OFDM system when executing the computer program stored in the memory.

[0032] An embodiment of the present application further provides a computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the steps of the peak-to-average ratio suppression method for an OFDM system as described above.

[0033] The embodiments of the present application provide a method, apparatus, device, and medium for suppressing peak-to-average ratio in an OFDM system. Compared with the prior art, the embodiments have the following beneficial effects:

[0034] The present application directly limits the time domain signal of the OFDM system, and improves the hyperbolic tangent function according to the appropriate compression coefficient set by the OFDM system during signal compression, and uses the improved hyperbolic tangent function to replace the compression function of the shearing noise compression algorithm CNC during compression, thereby using the improved hyperbolic tangent function to compress the sheared shearing noise. Since the hyperbolic tangent function is a continuous linear transformation, the nonlinear effect of the limiting operation on the signal can be reduced during compression, thereby enhancing the bit error rate performance and reducing out-of-band distortion.

[0035] Moreover, the limiting noise compression method proposed in this application compresses the noise signal after limiting and then adds it back to the original signal. Compared with the direct peak clipping of limiting filtering, less signal is lost. In addition, the fewer shearing times of the limiting noise compression method also make the in-band distortion smaller than that of limiting filtering algorithms, thus having better bit error rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of basic modulation operations of an OFDM system according to a peak-to-average ratio suppression method of an OFDM system provided in an embodiment of the present application;

[0037] Figure 2 A schematic diagram of a hyperbolic tangent compression function curve for a peak-to-average ratio suppression method for an OFDM system provided in an embodiment of the present application;

[0038] Figure 3 A schematic diagram of the overall flow of a peak-to-average ratio suppression method for an OFDM system provided in an embodiment of the present application;

[0039] Figure 4 A schematic diagram comparing the PAPR suppression performance of different algorithms for a peak-to-average ratio suppression method for an OFDM system provided in an embodiment of the present application;

[0040] Figure 5 A schematic diagram comparing the BER performance of different algorithms for a peak-to-average ratio suppression method for an OFDM system provided in an embodiment of the present application;

[0041] Figure 6This is a schematic diagram comparing the power spectra of OFDM signals after being processed by different algorithms of a peak-to-average ratio suppression method for an OFDM system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0042] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0043] See also Figure 3 , an embodiment of the present application provides a method for suppressing a peak-to-average ratio of an OFDM system, comprising the following steps:

[0044] Step 1: Frequency domain signal in OFDM system Perform inverse fast Fourier transform IFFT to obtain the time domain sequence signal .

[0045] Step 2: Time domain sequence signal Perform shearing so that the signal The amplitude is limited to the threshold And below, while the phase remains unchanged, the clipped signal is obtained .

[0046] Step 3: Obtain the clipping noise according to the limiting noise definition formula , and the shear noise is compressed according to the designed limiting noise compression algorithm based on hyperbolic function Compress to obtain the compressed shear noise signal .

[0047] Step 4: Cut the signal and the compressed shear noise signal The signal to be transmitted is obtained by adding:

[0048] .

[0049] Specifically:

[0050] like Figure 1The figure shows the basic principle block diagram of OFDM. The OFDM system modulates the bit stream onto multiple non-interfering subcarriers to increase the data transmission rate and system capacity. The subcarriers are required to be strictly orthogonal to ensure that the mutual correlation coefficient between them is zero. At the transmitting end of the OFDM system, the signal source first transmits serial binary bit data, which is converted into a parallel data stream after constellation mapping and serial-to-parallel conversion. Then, each symbol is placed on an orthogonal subcarrier and then superimposed to obtain the time domain signal to be transmitted. After the time domain signal is transmitted through the channel, the received signal is reversed at the receiving end to restore the original data.

[0051] Assume that the frequency domain data after constellation mapping is , The baseband signal is generated by the IFFT module, and the OFDM signal n The samples can be expressed by the following formula; In order to avoid spectrum aliasing and better simulate the peak-to-average ratio (PAPR) of continuous signals, the signal is oversampled, and the oversampling factor J Generally, 4 is taken; there are:

[0052] .

[0053] in: N Indicates the number of subcarriers.

[0054] The peak-to-average power ratio (PAPR) of an OFDM signal is defined as the ratio of the maximum power to the average power, expressed as:

[0055] .

[0056] in: Represents the time domain symbols after IFFT transformation. The Complementary Cumulative Distribution Function (CCDF) is usually used to measure the PAPR, indicating the probability that the signal is greater than a certain threshold value. Its CCDF is specifically expressed as:

[0057] .

[0058] In general, clipping and filtering reduces the peak-to-average ratio (PAPR) of the signal by clipping, and improves the signal distortion caused by clipping by filtering. However, the filtering operation after clipping will cause the peak to rise again, which generally reduces the peak-to-average ratio (PAPR) suppression performance. Therefore, it is necessary to repeat the clipping and filtering operations multiple times to achieve the predetermined PAPR suppression effect, namely the iterative clipping and filtering (ICF) technology. This multiple-iteration algorithm increases a lot of calculations. In order to reduce the computational complexity caused by iteration, a single-iteration algorithm of simplified clipping and filtering (SCF) technology can be used. The noise obtained by one clipping is multiplied by the proportional factor to replace the noise obtained by three clippings, reducing the number of iterations to one. Although the SCF algorithm reduces a large number of iterations, the frequency domain still requires three fast Fourier transforms / inverse fast Fourier transforms (FFT / IFFT). When the number of subcarriers is large, the frequency domain still requires three fast Fourier transforms / inverse fast Fourier transforms (FFT / IFFT). N When the noise is particularly large, the computational complexity is still very large. To address the problem of still large complexity, the Clipping-Noise Compression (CNC) algorithm is used to process the amplitude of the shear noise in the time domain. The algorithm mainly uses the improved The clipping noise is compressed using a compression function and then added back to the clipped signal to obtain the final transmission signal. This algorithm only requires one IFFT transformation, further reducing the computational complexity of the algorithm. To further reduce the computational complexity, the improved Airy compression function-based clipping noise suppression method (Clipping-Noise Compression Method Based Improved Airy Function, CNC-IAF) can be used. This method uses an improved Airy compression function to compress the clipping noise, suppressing the PAPR while improving the bit error rate and out-of-band distortion performance.

[0059] In the baseband signal processing of the limiting filter algorithm, for N For an OFDM system with multiple subcarriers, Nyquist sampling is required to avoid spectrum aliasing in signal processing and to better simulate the peak-to-average ratio characteristics of continuous signals. The specific limiting method is:

[0060] .

[0061] in: express Phase; The set clipping threshold is defined as:

[0062] .

[0063] in: represents the shear rate, which is related to the required PAPR suppression effect; Indicates the average power of the OFDM signal.

[0064] Then the limiting noise is:

[0065] .

[0066] The CNC algorithm compresses the limiting noise through the compression function to approximate the shear noise obtained by multiple iterations in the traditional limiting filter algorithm; in order to make the compression function work as much as possible In the compression interval, the amplitude of the noise signal is normalized and denormalized after the compression operation to keep the signal scale unchanged; thus, the complete The law limiting noise compression function is:

[0067] .

[0068] in: represents the compression coefficient; E[] represents the expectation; represents the phase of the noise signal; represents the average amplitude of the noise signal; the transmission signal obtained by the CNC algorithm is:

[0069] .

[0070] The CNC-IAF algorithm is based on the CNC algorithm and proposes a limiting noise compression function based on the improved Airy compression function:

[0071] .

[0072] in: represents the compression coefficient; the transmission signal obtained by the CNC-IAF algorithm is:

[0073] .

[0074] The clipping noise compression function in the shear noise compression method CNC has a problem of excessive nonlinear influence on the signal; even considering the case where the clipping ratio of the OFDM signal is 1, only about 1.83% of the clipping noise amplitude is greater than 1, about 34.96% of the amplitude is between 0 and 1, and the remaining about 60% of the noise amplitude is 0. The clipping ratio of the clipping algorithm in actual application is usually greater than 1, and the resulting clipping noise components with an amplitude of 0 will be more, and the components with an amplitude greater than 1 will be fewer. The compression function is The signal can be compressed well in the range of The signal amplitude will be expanded within the range of . From the previous analysis of the characteristics of the limiting noise, it can be seen that this will cause the signal between 0 and 1 to be changed too much, which accounts for a larger proportion but has little impact on high PAPR. The bit error rate performance of the law-limited noise compression algorithm is worse under the same PAPR suppression effect.

[0075] Some researchers have proposed a piecewise compression algorithm, which divides the compression function into segments and sets a compression threshold. Signals within the threshold remain unchanged, while signals outside the threshold are compressed using a logarithmic compression function. However, the proposed piecewise compression function cannot meet the requirement of infinite differentiability. If the compression function were infinitely differentiable, the out-of-band distortion it causes would be minimized.

[0076] Since the noise compression process is a nonlinear transformation, the analytical expression of the power spectrum density is mathematically difficult to handle. Here we assume that the input signal of the compression process is a periodic sine wave:

[0077] .

[0078] The input signal is compressed by the After that, the output signal is:

[0079] .

[0080] because It is also a periodic function with a period of ,so It can be expanded into a Fourier series:

[0081] .

[0082] Among them, the Fourier coefficient Represents the component of the signal in the frequency domain. The specific expression is:

[0083] .

[0084] In the Fourier series, is the main frequency component of the signal, and the others The terms correspond to higher-order harmonic components, which will leak out of the original signal bandwidth and form out-of-band interference. Therefore, the magnitude of the out-of-band interference depends on the higher-order harmonic components. The decay rate.

[0085] The Fourier analysis theory shows that the Fourier coefficients of a signal The decay rate of is closely related to the smoothness of the signal in the time domain (i.e., the continuity of the function and its derivative). and The derivative is continuous, then the Fourier coefficient The following relations are satisfied:

[0086] .

[0087] That is, if The smoother, the higher order the derivative is, the Fourier coefficient The faster the decay rate, the When it is an infinitely differentiable function, all derivatives are continuous, and the corresponding Fourier coefficients The decay rate is the fastest, making The high-order harmonic components can be almost ignored, which can effectively reduce out-of-band interference. Output signal of The derivative can be expressed as:

[0088] .

[0089] in, and is continuous, so The continuity of The continuity of the derivative of . Then if is infinitely differentiable, then all The derivatives are all continuous. All derivatives of are all continuous, the Fourier coefficients The corresponding higher harmonics will The smoothness is improved and the decay is fast.

[0090] From the above analysis, we can see that to minimize out-of-band interference, the compression function needs to be infinitely differentiable. A piecewise function obviously cannot meet the infinitely differentiable condition at the segment level, so this approach will cause significant out-of-band distortion. Therefore, a smooth compression function is needed to compress the clipping noise. Based on this, a clipping noise compression algorithm based on the hyperbolic tangent function is proposed.

[0091] The specific construction process of the compression function based on the hyperbolic function improvement of this application is as follows:

[0092] The compression and expansion function of the OFDM system at the transmitting end is:

[0093] .

[0094] in: Represents the original signal The average amplitude of and represents the compression parameter; tanh represents the hyperbolic tangent function, specifically:

[0095] .

[0096] This application adopts the same idea as the CNC algorithm, and performs compression transformation in the time domain for the noise caused by shearing, compressing the noise with higher amplitude while keeping the amplitude of other noise unchanged to reduce distortion; at the same time, the hyperbolic tangent function is improved, and the improved noise compression function is proposed as follows:

[0097] .

[0098] in: Represents the compression coefficient, which is used to control the shape of the compression function, the compression curve of the new compression function, and The law compression curve and the Airy function compression curve are as follows Figure 2 As shown, it can be seen that the new compression function satisfies When the signal amplitude remains almost unchanged, , the signal amplitude is compressed.

[0099] exist Figure 2 In the figure, the curve represented by Hyperbolic tangent function (k=0.5) represents the compression curve of the new compression function proposed in this application when the compression coefficient k=0.5; the curve represented by Hyperbolic tangent function (k=2) represents the compression curve of the new compression function proposed in this application when the compression coefficient k=2; the curve represented by μ-lawfunction (μ=2) represents the compression curve of the new compression function proposed in this application when the compression coefficient μ=2 The curve represented by μ-law function (μ=10) represents the compression coefficient μ=10. The curve represented by Airy function (alpha=0.35) represents the Airy function compression curve when the compression coefficient alpha=0.35; the curve represented by Airy function (alpha=0.45) represents the Airy function compression curve when the compression coefficient alpha=0.45; the curve represented by Original signal represents the curve of the original signal.

[0100] At this time, we hope that the amplitude of the shear noise can be compressed, that is, the noise signal can be as close as possible to the Therefore, the limiting noise is normalized, that is, , and after the compression operation, denormalization is performed to keep the signal scale unchanged, thus obtaining the new complete limiting noise compression function:

[0101] .

[0102] in: Represents the original signal The average amplitude of .

[0103] If the compression function satisfies infinite differentiability, the out-of-band distortion caused by it can be minimized; since the hyperbolic tangent function is an infinitely differentiable function, then according to the chain rule, is also an infinitely differentiable function, is a constant, so It also satisfies infinite differentiability, so the new compression function proposed in this application can minimize out-of-band distortion; on the other hand, since the amplitude distribution of OFDM signal obeys Rayleigh distribution, the probability of its peak distribution is low, but the amplitude is much higher than the mean, that is, in the formula The probability of this happening is very high, so most signals can work in the compression range.

[0104] Simulation experiment:

[0105] This application uses comparative simulation to verify the performance of the algorithm. The peak-to-average ratio suppression algorithms involved in the comparison include the iterative clipping filter algorithm ICF and the simplified clipping filter algorithm SCF. The ICF algorithm is used to compress the noise of the airy function, and the ICF algorithm is used to compress the noise of the airy function. K =3; the specific simulation parameters are shown in Table 1.

[0106] Table 1 Simulation experiment parameters

[0107]

[0108] like Figure 4 The figure shows the PAPR suppression performance comparison between the original signal and the signal processed by different algorithms. From the simulation results, it can be seen that compared with the limiting filter type ICF and SCF algorithms, the limiting noise compression algorithm has better PAPR suppression performance. is 8, the CNC-IAF algorithm is 0.7, the HTCNC algorithm When the CCDF probability is 0.5, the PAPR suppression performance of the HTCNC algorithm is slightly better than the other two algorithms. -3When , the PAPR value of the CNC algorithm is about 4.92dB, the PAPR value of the CNC-IAF algorithm is about 4.78dB, and the PAPR value of the HTCNC algorithm is about 4.63dB. Therefore, it can be seen that the algorithm proposed in this application has better PAPR suppression performance than the CNC algorithm and the CNC-IAF algorithm.

[0109] The signals processed by the above PAPR suppression algorithms are passed through an Additive White Gaussian Noise (AWGN) channel and then demodulated to evaluate the bit error rate (BER) performance of the signals processed by these algorithms.

[0110] like Figure 5 As shown in the figure, the BER performance comparison of the ICF algorithm, SCF algorithm, CNC algorithm, CNC-IAF algorithm and the algorithm proposed in this application is shown; it can be seen that the bit error rate performance of the limiting filter type algorithms ICF and SCF is the worst, and the bit error rate performance of the three limiting noise compression type algorithms is similar, and is significantly better than ICF and SCF; this phenomenon is due to the fact that the limiting noise compression type algorithms compress the noise signal after limiting and then add the original signal back, so the direct peak clipping of the limiting filter type algorithm results in less signal loss, and the fewer shearing times of the limiting noise compression type algorithm also makes the in-band distortion less than that of the limiting filter type algorithm, so it has better bit error rate performance; in addition, among the limiting filter type algorithms, when the signal-to-noise ratio is 10, the bit error rate performance of the CNC algorithm is similar to that of the CNC-IAF algorithm, and the bit error rate of the HTCNC algorithm is slightly better than the above two algorithms. -3 When the required signal-to-noise ratio (SNR) of the algorithm proposed in this application is close to that of the CNC algorithm, and is about 0.2dB lower than that of the CNC-IAF algorithm. Therefore, the bit error rate performance of the algorithm proposed in this application is generally better than that of the other two limiting noise compression algorithms.

[0111] like Figure 6 As shown in the figure, it is the power spectral density (PSD) diagram of the OFDM output signal under different methods; it can be seen that the limiting filtering algorithms ICF and SCF have undergone filtering operations, and the out-band components are very close to the original signal; the limiting noise compression algorithms have not undergone filtering, and the out-band components are significantly increased. Among them, the out-band components of the CNC algorithm and the CNC-IAF algorithm are basically similar, but the out-band component of the algorithm proposed in this application is smaller than that of the other two algorithms. Therefore, compared with the CNC algorithm and the CNC-IAF algorithm, the algorithm proposed in this application has a stronger anti-interference ability against out-of-band noise.

[0112] Based on the shear noise compression algorithm CNC, this application adopts the improved hyperbolic tangent function as a new compression function to design an improved limiting noise compression algorithm HTCNC; the algorithm proposed in this application directly limits the signal in the time domain, and uses the improved hyperbolic tangent function to compress the limiting noise after limiting, so as to reduce the nonlinear effect of the limiting operation on the signal, enhance the bit error rate performance and reduce out-of-band distortion.

[0113] The embodiment of the present application further provides a peak-to-average ratio suppression device for an OFDM system, comprising:

[0114] The signal processing module is used to obtain the OFDM time domain signal of the OFDM system; perform a shearing operation on the OFDM time domain signal to obtain a sheared signal, and obtain shearing noise according to the difference between the time domain signal and the sheared signal.

[0115] A function module is used to extract the compression coefficient of the limiting noise compression function in the shear noise compression method CNC; multiply the independent variable of the hyperbolic tangent function by the compression coefficient to form an improved independent variable, form an improved hyperbolic tangent function according to the improved independent variable, and use the ratio of the improved hyperbolic tangent function to the hyperbolic tangent function as an improved noise compression function, and form an improved limiting noise compression function according to the improved noise compression function.

[0116] The noise compression module is used to compress the shear noise according to the improved limiting noise compression function and compression threshold value while keeping the phase of the noise unchanged. The shear noise with a noise amplitude greater than the compression threshold value is compressed once, and the shear noise with a noise amplitude less than the compression threshold value remains unchanged, thereby obtaining a compressed shear noise signal.

[0117] The suppression module is used to add and correct the compressed shear noise signal and the shear signal to obtain an OFDM time domain signal with a peak-to-average ratio suppressed.

[0118] An embodiment of the present application also provides an electronic device, including a memory and a processor.

[0119] The memory is used to store computer programs.

[0120] When the processor is used to execute the computer program stored in the memory, the steps of the above-mentioned method for suppressing peak-to-average ratio of an OFDM system are implemented.

[0121] An embodiment of the present application further provides a computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for suppressing peak-to-average ratio of an OFDM system.

[0122] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A peak-to-average ratio suppression method for an OFDM system, characterized in that: The following steps are involved: An OFDM time domain signal of an OFDM system is obtained; a shearing operation is performed on the OFDM time domain signal to obtain a sheared signal, and shearing noise is obtained according to a difference between the time domain signal and the sheared signal; Extract the compression coefficient of the limiting noise compression function in the shear noise compression method CNC; Multiplying the independent variable of the hyperbolic tangent function by the compression coefficient to form an improved independent variable, forming an improved hyperbolic tangent function based on the improved independent variable, using the ratio of the improved hyperbolic tangent function to the hyperbolic tangent function as an improved noise compression function, and forming an improved limited noise compression function based on the improved noise compression function; According to the improved limiting noise compression function and compression threshold, the shear noise is compressed while keeping the phase of the noise unchanged. The shear noise with a noise amplitude greater than the compression threshold is compressed once, while the shear noise with a noise amplitude less than the compression threshold remains unchanged, thus obtaining a compressed shear noise signal. The compressed shear noise signal is added to the shear signal to correct it, and the OFDM time domain signal with peak-to-average ratio suppressed is obtained; It also includes performing denormalization on the shearing noise after obtaining the shearing noise to scale the shearing noise, and the denormalization method is: x=|c(n)| / E[|c(n)|]; Where: c(n) represents shear noise; E[] represents expectation; The acquisition of the improved noise compression function includes: According to the noise compression coefficient, the shape of the compression function is controlled, and the hyperbolic tangent function is improved at the same time. The improved noise compression function is: Where: k represents the compression coefficient; tanh() represents the hyperbolic tangent function; x represents shear noise; The improved limiting noise compression function is: Where: E[|c(n)|] represents the average amplitude of the original signal c(n); k represents the compression coefficient; tanh() represents the hyperbolic tangent function; represents the shear noise after inverse normalization; φ c (n) represents the phase of the noise signal.

2. The peak-to-average ratio suppression method for an OFDM system according to claim 1, wherein: The method of adding and correcting the compressed shear noise signal and the shear signal to obtain the OFDM time domain signal after the peak-to-average ratio is as follows: in: Indicates shear signal; c c (n) represents the compressed shear noise signal.

3. A peak-to-average ratio suppression device for an OFDM system, characterized in that: include: The signal processing module is used to obtain an OFDM time domain signal of the OFDM system; perform a shearing operation on the OFDM time domain signal to obtain a sheared signal, and obtain shearing noise according to the difference between the time domain signal and the sheared signal; Function module, used for extracting compression coefficient of limiting noise compression function in shear noise compression method CNC; Multiplying the independent variable of the hyperbolic tangent function by the compression coefficient to form an improved independent variable, forming an improved hyperbolic tangent function based on the improved independent variable, using the ratio of the improved hyperbolic tangent function to the hyperbolic tangent function as an improved noise compression function, and forming an improved limited noise compression function based on the improved noise compression function; A noise compression module is used to compress the shear noise according to the improved limiting noise compression function and the compression threshold value while keeping the phase of the noise unchanged. The shear noise with a noise amplitude greater than the compression threshold value is compressed once, and the shear noise with a noise amplitude less than the compression threshold value remains unchanged, thereby obtaining a compressed shear noise signal. A suppression module is used to add and correct the compressed shear noise signal and the shear signal to obtain an OFDM time domain signal with a peak-to-average ratio suppressed; It also includes performing denormalization on the shearing noise after obtaining the shearing noise to scale the shearing noise, and the denormalization method is: x=|c(n)| / E[|c(n)|]; Where: c(n) represents shear noise; E[] represents expectation; The acquisition of the improved noise compression function includes: According to the noise compression coefficient, the shape of the compression function is controlled, and the hyperbolic tangent function is improved at the same time. The improved noise compression function is: Where: k represents the compression coefficient; tanh() represents the hyperbolic tangent function; x represents shear noise; The improved limiting noise compression function is: Where: E[|c(n)|] represents the average amplitude of the original signal c(n); k represents the compression coefficient; tanh() represents the hyperbolic tangent function; represents the shear noise after inverse normalization; φ c (n) represents the phase of the noise signal.

4. An electronic device, characterized in that: include: memory and processor; The memory is used to store computer programs; The processor is configured to implement the steps of a peak-to-average ratio suppression method for an OFDM system as claimed in any one of claims 1 to 2 when executing the computer program stored in the memory.

5. A computer-readable storage medium, characterized in that Used to store a computer program, which, when executed by a processor, implements the steps of a peak-to-average ratio suppression method for an OFDM system as claimed in any one of claims 1 to 2.

Images