A soft peak clipping method and device for suppressing peak-to-average ratio in OFDM

Abstract

The present application relates to a soft peak clipping method and device for suppressing peak-to-average ratio (PAR) for OFDM, and relates to the field of signal processing technology. The method comprises: calculating the envelope amplitude value of the in-phase and quadrature signals based on the in-phase and quadrature components of the in-phase and quadrature signals obtained by OFDM modulation; calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude value of the in-phase and quadrature signals; wherein the peak clipping function is determined by a peak clipping threshold and a basic function, the peak clipping threshold is determined by the PAR, and the basic function includes any one of a Rapp model function, a Logistic function, and an inverse tangent function; and reducing the in-phase and quadrature components based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping. The present application can ensure that the OFDM signal after peak clipping meets the requirements of the spectrum emission template, while ensuring that the error vector amplitude performance meets the requirements.

Description

Technical Field

[0001] The present application relates to the field of signal processing technology, and more specifically, to a soft peak clipping method and device for suppressing peak-to-average ratio in OFDM. Background Art

[0002] In broadband communication system transmitters, OFDM (Orthogonal Frequency Division Multiplexing) signals have a high peak-to-average power ratio (PAPR). This can affect the performance of nonlinear devices, particularly power amplifiers, during signal transmission, exacerbating nonlinear distortion in transmitted signals or reducing system power efficiency. Therefore, reducing the PAPR of OFDM signals is crucial for improving the efficiency of broadband transmitter systems.

[0003] Existing methods generally reduce the peak-to-average ratio of OFDM signals by hard peak clipping. Specifically, the peak-to-average ratio of signals is reduced by cutting the amplitude of signals exceeding a threshold to a threshold value.

[0004] However, hard peak clipping will cause signal distortion, which in turn leads to enhanced out-of-band radiation, making the OFDM signal after peak clipping unable to meet the requirements of the spectrum emission mask. Summary of the Invention

[0005] The present application is provided to address the aforementioned problems existing in the prior art. According to an embodiment of the present application, a soft peak clipping method and apparatus for suppressing peak-to-average ratio for OFDM can ensure that the OFDM signal after peak clipping meets the requirements of the spectrum emission mask while ensuring that the error vector amplitude performance meets the requirements.

[0006] In a first aspect, the present application provides a soft peak clipping method for suppressing peak-to-average ratio for OFDM, comprising:

[0007] Calculating the envelope amplitude value of the in-phase and quadrature signals based on the in-phase and quadrature components of the in-phase and quadrature signals obtained by orthogonal frequency division multiplexing (OFDM) modulation;

[0008] Calculating the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals; wherein the peak clipping function is determined by a peak clipping threshold and a basis function, the independent variable of the peak clipping function is the envelope amplitude value of the in-phase and quadrature signals before peak clipping, and the dependent variable is the envelope amplitude value of the in-phase and quadrature signals after peak clipping; the peak clipping threshold is determined by a peak-to-average ratio, and the basis function includes any one of a Rapp model function, a Logistic function, and an inverse tangent function;

[0009] The in-phase component and the quadrature component are reduced based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping.

[0010] In a second aspect, an embodiment of the present application provides a soft peak clipping device for suppressing peak-to-average ratio for OFDM, comprising:

[0011] A calculation module is configured to calculate the envelope amplitude value of the in-phase and quadrature signals obtained by OFDM modulation based on the in-phase component and the quadrature component of the in-phase and quadrature signals; and calculate the envelope amplitude value of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude value of the in-phase and quadrature signals; wherein the peak clipping function is determined by a peak clipping threshold and a basis function, the independent variable of the peak clipping function is the envelope amplitude value of the in-phase and quadrature signals before peak clipping, and the dependent variable is the envelope amplitude value of the in-phase and quadrature signals after peak clipping, the peak clipping threshold is determined by a peak-to-average ratio, and the basis function includes any one of a Rapp model function, a Logistic function, and an inverse tangent function;

[0012] The compression module is configured to reduce the in-phase component and the quadrature component based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping.

[0013] In a third aspect, an embodiment of the present application provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the method described in any of the above embodiments.

[0014] In a fourth aspect, an embodiment of the present application provides a non-transitory computer-readable storage medium having computer-executable instructions stored thereon. When the computer-executable instructions are executed by a processor, the method described in any of the above embodiments is implemented.

[0015] The beneficial effect of the embodiments of the present application is that soft peak clipping of an OFDM signal based on a peak clipping function ensures that the clipped OFDM signal meets the requirements of the spectrum emission mask while ensuring that the error vector magnitude (EVM) performance meets the requirements. Compared to hard peak clipping, the soft peak clipping solution provided by the embodiments of the present application achieves smoother peak compression, significantly improving the spectral performance of the clipped signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar components in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar components. The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the description and claims, serve to illustrate the disclosed embodiments. Where appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive of the embodiments of the present apparatus or method.

[0017] Figure 1This is a flow chart of a soft peak clipping method for suppressing peak-to-average ratio for OFDM provided by an embodiment of the present application;

[0018] Figure 2 1 is a different peak clipping function curve provided by an embodiment of the present application;

[0019] Figure 3 This is a schematic diagram of area division provided by an embodiment of the present application;

[0020] Figure 4 This is a schematic diagram of the relationship between frequency domain and power spectral density provided by an embodiment of the present application;

[0021] Figure 5 1 is a schematic diagram of a soft peak clipping device for suppressing peak-to-average ratio for OFDM provided by an embodiment of the present application;

[0022] Figure 6 This is a schematic diagram of an OFDM transmission system architecture provided by an embodiment of the present application. DETAILED DESCRIPTION

[0023] To enable those skilled in the art to better understand the technical solution of the present application, the present application is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and specific embodiments, but are not intended to limit the present application. The terms "first," "second," and "third" used in this application are merely intended to distinguish corresponding features, and do not necessarily represent a need for such an order, nor do they necessarily represent only the singular form.

[0024] like Figure 1 As shown, the embodiment of the present application provides a soft peak clipping method for suppressing peak-to-average ratio for OFDM, including:

[0025] Step 101: Calculate the envelope amplitude value of the in-phase and quadrature signals based on the in-phase and quadrature components of the in-phase and quadrature signals obtained by OFDM modulation.

[0026] The method provided in the embodiment of the present application is applicable to communication scenarios based on OFDM technology, including LTE and WLAN scenarios, and is not affected by the specific signal standard. It is applicable to signal standards such as HT (High Throughput), VHT (Very High Throughput), and HE (High Efficiency) in WLAN.

[0027] To ensure that the error vector magnitude (EVM) of the signal after soft clipping meets transmission requirements, this method is applicable to transmission modes with an MCS (Modulation and Coding Scheme) value not exceeding 5. For example, in a 1x1HT scenario, the corresponding modulation scheme is 64-QAM with a code rate of 2 / 3; for a 20M bandwidth signal, the corresponding transmission rate does not exceed 57.8Mbps; for a 40M bandwidth signal, the corresponding transmission rate does not exceed 120.0Mbps.

[0028] In addition, this method is applicable to low-order modulation scenarios. Specifically, the modulation order does not exceed 6. That is, it does not exceed the order of "64-QAM" (64-Quadrature Amplitude Modulation). Modulation modes that meet this condition include: BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16-QAM (16-Quadrature Amplitude Modulation), and 64-QAM.

[0029] Specifically, the envelope amplitude value of the in-phase and quadrature signals can be calculated by formula (1).

[0030]

[0031] Wherein, a(n) is used to characterize the envelope amplitude value of the in-phase and quadrature signals before peak clipping, i(n) is used to characterize the in-phase component, and q(n) is used to characterize the quadrature component.

[0032] The envelope amplitude values ​​of the in-phase and quadrature signals can also be calculated by linear approximation, as shown in formula (2).

[0033]

[0034] in, It is used to represent the envelope amplitude value of the in-phase and quadrature signals after peak clipping. M is used to represent the maximum value of the absolute value of the in-phase component and the absolute value of the quadrature component. m is used to represent the minimum value of the absolute value of the in-phase component and the absolute value of the quadrature component.

[0035] Alternatively, CORDIC (Coordinate Rotation Digital Computer) can be used to calculate the envelope amplitude values ​​of the in-phase and quadrature signals. This method only involves simple addition, subtraction, multiplication, and division operations, which is easy to implement in hardware. The calculation accuracy is higher than that of linear approximation, and the phase value can be obtained at the same time as the amplitude is calculated.

[0036] In actual application scenarios, any of the above methods can be used to calculate the envelope amplitude value according to actual needs.

[0037] Step 102: Calculate the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals.

[0038] The peak clipping function is determined by a peak clipping threshold and a basic function. The independent variable of the peak clipping function is the envelope amplitude value of the in-phase and quadrature signals before peak clipping, and the dependent variable is the envelope amplitude value of the in-phase and quadrature signals after peak clipping. The peak clipping threshold is determined by the peak-to-average ratio, and the basic function includes: any one of a Rapp model function, a Logistic function, and an inverse tangent function.

[0039] The smaller the peak clipping threshold, the lower the peak-to-average ratio (PAR) of the clipped signal. Therefore, the peak clipping threshold can be set based on the PAR requirement. Furthermore, since a smaller PAR deteriorates the spectrum emission mask and error vector magnitude (EVM) performance, the peak clipping threshold can be set based on the PAR, spectrum emission mask, and EVM. Therefore, as long as the spectrum emission mask and EVM meet the transmit signal standard, the lower the peak clipping threshold, the better.

[0040] In actual application scenarios, the peak clipping threshold A can be set based on the MCS value and the signal average power E. The smaller the MCS value, the smaller E and A.

[0041] The peak clipping function needs to meet the following conditions: (1) it should be close to the hard peak clipping function to ensure peak clipping performance; (2) it should have good continuity to reduce out-of-band radiation. Based on the above two points, the basic functions that can be used include: Rapp model function, Logistic function and inverse tangent function.

[0042] Step 103: Based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping, reduce the in-phase component and the quadrature component.

[0043] This embodiment of the present application performs soft peak clipping on an OFDM signal based on a peak clipping function. This ensures that the clipped OFDM signal meets the requirements of the spectrum emission mask while ensuring that the error vector magnitude (EVM) performance meets the requirements. Compared to hard peak clipping, the soft peak clipping solution provided by this embodiment of the application achieves smoother peak compression, significantly improving the spectral performance of the clipped signal.

[0044] In one embodiment of the present application, the basis function is a Rapp model function;

[0045] The peak clipping function is shown in formula (3):

[0046]

[0047] Among them, a(n) is used to represent the envelope amplitude value of the in-phase and quadrature signals before peak clipping. It is used to characterize the envelope amplitude value of the in-phase and quadrature signals after peak clipping. A is used to characterize the peak clipping threshold. p is used to characterize the peak clipping parameter. The peak clipping parameter is determined by the spectrum emission template and the error vector magnitude.

[0048] The smaller p is, the more pronounced the peak-to-average ratio suppression effect is, and the spectrum emission mask margin is improved, but the error vector magnitude deteriorates more severely. The value of p ranges from [1, 8]. In the embodiment of this application, when p = 2, the peak-to-average ratio, spectrum emission mask, and error vector magnitude are well balanced.

[0049] This embodiment of the present application utilizes a modified Rapp model function to generate a peak-clipping function. This function exhibits good continuity and approaches the peak-clipping threshold, thereby reducing out-of-band emissions. Furthermore, the peak-clipping parameters can be adjusted based on the peak-to-average ratio (PAR) of the clipped signal, the spectrum emission mask, and the error vector magnitude (EVM) to meet the needs of different scenarios.

[0050] In one embodiment of the present application, the basis function is a logistic function;

[0051] Based on the preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals, the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping are calculated, including:

[0052] In response to the envelope amplitude value of the in-phase and quadrature signals before peak clipping being greater than a first threshold, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping based on the peak clipping function and the envelope amplitude value of the in-phase and quadrature signals;

[0053] The peak clipping function is shown in formula (4):

[0054]

[0055] Among them, a(n) is used to represent the envelope amplitude value of the in-phase and quadrature signals before peak clipping. It is used to characterize the envelope amplitude value of the in-phase and quadrature signals after peak clipping. A is used to characterize the peak clipping threshold. k is used to characterize the first parameter, which is determined by the spectrum emission template and the error vector magnitude. c is used to characterize the second parameter, which is calculated from the peak clipping threshold, the first threshold, and the first parameter.

[0056] In response to the envelope amplitude values ​​of the in-phase and quadrature signals before peak clipping being no greater than a first threshold, the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping are the same, i.e., soft clipping is not performed on the in-phase and quadrature signals whose envelope amplitude values ​​are no greater than the first threshold. Based on this, the method further includes: terminating the current process in response to the envelope amplitude values ​​of the in-phase and quadrature signals before peak clipping being no greater than the first threshold.

[0057] The second parameter is shown in formula (5).

[0058]

[0059] Among them, A0 is used to represent the first threshold.

[0060] It should be noted that in practical applications, Equations (4) and (5) can be modified. That is, the peak clipping function derived from the Logistic function can have different forms. For example, the first parameter does not exist in Equation (5), meaning that the calculation of the second parameter is independent of the first parameter. The first parameter is determined solely by the spectrum emission template.

[0061] The smaller the value of A0, the better the peak-to-average ratio suppression effect, but the worse the spectrum emission mask and error vector magnitude performance. The value of k ranges from [0, 8]. The smaller the value of k, the better the peak-to-average ratio suppression effect, but the worse the spectrum emission mask and error vector magnitude performance. In this embodiment of the application, A0 is three-quarters of A, and k is 4.

[0062] The peak clipping function derived from the Logistic function exhibits good continuity and approaches the peak clipping threshold, reducing out-of-band emissions. Furthermore, the first parameter can be adjusted based on the spectrum emission mask and error vector magnitude requirements to meet the needs of different scenarios. The first threshold can be used to select in-phase and quadrature signals requiring peak clipping, reducing the computational complexity of peak clipping.

[0063] In one embodiment of the present application, the basis function is an inverse tangent function;

[0064] Based on the preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals, the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping are calculated, including:

[0065] In response to the envelope amplitude value of the in-phase and quadrature signals before peak clipping being greater than a second threshold, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping based on the peak clipping function and the envelope amplitude value of the in-phase and quadrature signals;

[0066] The peak clipping function is shown in formula (6):

[0067]

[0068] Among them, a(n) is used to represent the envelope amplitude value of the in-phase and quadrature signals before peak clipping. It is used to characterize the envelope amplitude value of the in-phase and quadrature signals after peak clipping. A is used to characterize the peak clipping threshold. a It is used to characterize the third parameter, which is determined by the spectrum emission template and the error vector magnitude. A1 is used to characterize the second threshold.

[0069] In response to the envelope amplitude values ​​of the in-phase and quadrature signals before peak clipping being no greater than a second threshold, the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping are the same, i.e., soft clipping is not performed on the in-phase and quadrature signals whose envelope amplitude values ​​are no greater than the second threshold. Based on this, the method further includes: terminating the current process in response to the envelope amplitude values ​​of the in-phase and quadrature signals before peak clipping being no greater than the second threshold.

[0070] The peak clipping function based on the inverse tangent function may be in other forms, such as when the third parameter is determined only by the error vector magnitude.

[0071] The smaller the value of A1, the better the peak-to-average ratio suppression effect, but the worse the spectrum emission mask and error vector magnitude performance. The value of k ranges from [0, 4]. The smaller the value of k, the better the peak-to-average ratio suppression effect, but the worse the spectrum emission mask and error vector magnitude performance. In this embodiment of the application, A1 is three-quarters of A, and k is 2.

[0072] The peak clipping function derived from the inverse tangent function exhibits good continuity and approaches the peak clipping threshold, reducing out-of-band emissions. Furthermore, the third parameter can be adjusted based on the spectrum emission mask and error vector magnitude requirements to meet the needs of different scenarios. The second threshold can be used to select in-phase and quadrature signals requiring peak clipping, reducing the computational complexity of peak clipping.

[0073] like Figure 2 The following figure shows different peak clipping function curves. The horizontal axis represents the normalized input amplitude, and the vertical axis represents the normalized output amplitude. Hard clipping refers to the hard clipping function curve; rapp refers to the Rapp model function, with the peak clipping parameters of the two Rapp model function curves being 2 and 6, respectively; logistic-based refers to a peak clipping function derived from the logistic function; and arctan-based refers to a peak clipping function derived from the inverse tangent function.

[0074] In one embodiment of the present application, reducing the in-phase component and the quadrature component based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping includes:

[0075] Calculating a compression coefficient based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping; wherein the compression coefficient is the ratio of the envelope amplitude value of the in-phase and quadrature signals after peak clipping to the envelope amplitude value of the in-phase and quadrature signals before peak clipping;

[0076] Determine the in-phase component after reduction as the product of the in-phase component before reduction and the compression coefficient;

[0077] The orthogonal component after reduction is determined to be the product of the orthogonal component before reduction and the compression coefficient.

[0078] The embodiment of the present application reduces the in-phase component and the quadrature component in proportion to the compression coefficient to facilitate subsequent transmission.

[0079] In one embodiment of the present application, based on a preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals, calculating the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping includes:

[0080] Based on the envelope amplitude values ​​of the in-phase and quadrature signals before peak clipping, a predetermined conversion table is queried to obtain the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping. The conversion table includes: a value interval of the envelope amplitude values ​​of the in-phase and quadrature signals before peak clipping, and the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping corresponding to the value interval, and the value interval is determined by the derivative of the peak clipping function.

[0081] Considering that each peak clipping operation requires a high hardware consumption due to the calculation of the peak clipping function, the embodiment of the present application pre-establishes a conversion table based on the peak clipping function. The conversion table can be queried based on the envelope amplitude values ​​of the in-phase and quadrature signals before peak clipping to obtain the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping. This table lookup method does not require complex calculations and consumes less hardware.

[0082] In one embodiment of the present application, the method further includes: dividing the value of the independent variable of the peak clipping function into a plurality of value intervals based on the derivative of the peak clipping function; calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping corresponding to each value interval based on the value intervals and the peak clipping function; and generating a conversion table based on the value intervals and the corresponding envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping;

[0083] Among them, the value range includes: a linear region, a transition region and a saturation region; in the linear region, the difference between the derivative of the peak clipping function and 1 is less than a preset first threshold, and in the saturation region, the derivative of the peak clipping function is less than a preset second threshold; in the linear region, the transition region and the saturation region, the derivative of the peak clipping function decreases successively.

[0084] The first threshold and the second threshold can be set based on the needs of actual business scenarios. For example, the first threshold is 0.01 and the second threshold is 0.1.

[0085] like Figure 3 As shown in the figure, the horizontal axis is the normalized input amplitude value, which is the envelope amplitude value of the in-phase and quadrature signals before peak clipping. The vertical axis is the normalized output amplitude value, which is the envelope amplitude value of the in-phase and quadrature signals after peak clipping. S1 is the boundary between the linear region and the transition region, and S2 is the boundary between the transition region and the saturation region.

[0086] The linear region is (0, S1]. For in-phase and quadrature signals whose envelope amplitude values ​​are in the linear region, there is no need to perform soft peak clipping.

[0087] The transition region is (S1, S2]. For query accuracy, the transition region can be further divided into H subintervals. The value of the peak clipping function is calculated based on the midpoint of each subinterval to obtain the envelope amplitude value of the in-phase and quadrature signals after peak clipping corresponding to each subinterval. H is an integer greater than 1.

[0088] For the hth subinterval, the value range of the subinterval is (S1+(h-1)×g,S1+h×g], where g is the interval of the subinterval and the midpoint of the hth subinterval is b h =S1+(h-0.5)×g, the corresponding envelope amplitude value before normalization is B h =A×[S1+(h-0.5)×g], substitute this value into the peak clipping function to obtain the envelope amplitude value of the in-phase and quadrature signals after peak clipping corresponding to the midpoint.

[0089] The saturation region is (S2, +∞). If the normalized input amplitude value is greater than S2, the normalized output amplitude value is 1.

[0090] The normalized input amplitude and output amplitude are shown in Table 1, where the normalized input amplitude is a and f(·) is used to characterize the peak clipping function.

[0091] Table 1

[0092]

[0093] The more subintervals the transition zone is divided into, the greater the table lookup overhead is, but the smaller the error of the output result is. The specific number of subintervals can be set according to actual needs.

[0094] The embodiment of the present application provides an optional parameter setting, where S1 is 0.5, S2 is 2.1, and H is 128. Taking the Rapp model function with p=2 as an example, the corresponding normalized input amplitude and normalized output amplitude are shown in Table 2.

[0095] Table 2

[0096]

[0097]

[0098] The soft clipping method provided by the above embodiment can reduce power consumption. This is because, after soft clipping, the low-order modulated OFDM signal has a low peak-to-average ratio, provided that transmission conditions are met. This allows the power amplifier to operate near saturation, resulting in higher power-added efficiency and effectively reduced operating power. Furthermore, compared to hard clipping, soft clipping has a smoother clipping function, effectively reducing out-of-band radiation components while ensuring that the error vector amplitude meets requirements.

[0099] Taking the Rapp model function as an example, the peak-to-average ratio and error vector magnitude (EVM) for different clipping conditions are shown in Table 3. As can be seen from Table 3, by ensuring that the EVM meets the requirements for low-order modulation signal transmission, soft clipping can reduce the peak-to-average ratio from 9.3 dB to 5.4 dB, significantly improving the power amplifier's operating efficiency.

[0100] Table 3

[0101]

[0102] like Figure 4 As shown, the horizontal axis is frequency, the vertical axis is relative power spectral density, Original is the initial signal, without any peak clipping operation, the peak-to-average ratio is 9.3dB, and the error vector magnitude is -51.43dB; Hard Clipping is the signal after hard peak clipping, the peak-to-average ratio is 5.4dB, and the error vector magnitude is -23.09dB; Soft Clipping is the signal after soft peak clipping, the peak-to-average ratio is 5.4dB, and the error vector magnitude is -21.19dB; Mask is the spectrum emission template, which stipulates the frequency domain energy distribution of the transmitted signal, which cannot exceed this template. Figure 4 The power spectrum value of the hard-clipped signal exceeds the spectrum emission mask and does not meet the transmitter performance requirements.

[0103] like Figure 5 As shown, the embodiment of the present application provides a soft peak clipping device for suppressing peak-to-average ratio for OFDM, including:

[0104] A calculation module 501 is configured to calculate the envelope amplitude value of the in-phase and quadrature signals obtained by OFDM modulation based on the in-phase component and the quadrature component of the in-phase and quadrature signals; and calculate the envelope amplitude value of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude value of the in-phase and quadrature signals. The peak clipping function is determined by a peak clipping threshold and a basis function, the independent variable of the peak clipping function is the envelope amplitude value of the in-phase and quadrature signals before peak clipping, and the dependent variable is the envelope amplitude value of the in-phase and quadrature signals after peak clipping. The peak clipping threshold is determined by a peak-to-average ratio, and the basis function includes any one of a Rapp model function, a Logistic function, and an inverse tangent function.

[0105] The compression module 502 is configured to reduce the in-phase component and the quadrature component based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping.

[0106] In one embodiment of the present application, wherein the basis function is a Rapp model function;

[0107] The peak clipping function is shown in formula (3).

[0108] In one embodiment of the present application, wherein the basis function is a logistic function;

[0109] Calculating the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals includes:

[0110] In response to the envelope amplitude value of the in-phase and quadrature signals before peak clipping being greater than a first threshold, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping based on the peak clipping function and the envelope amplitude value of the in-phase and quadrature signals;

[0111] The peak clipping function is shown in formula (4).

[0112] In one embodiment of the present application, the basis function is an inverse tangent function;

[0113] Calculating the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals includes:

[0114] In response to the envelope amplitude value of the in-phase and quadrature signals before peak clipping being greater than a second threshold, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping based on the peak clipping function and the envelope amplitude value of the in-phase and quadrature signals;

[0115] The peak clipping function is shown in formula (6).

[0116] In one embodiment of the present application, the compression module 502 is configured to calculate a compression coefficient based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping; wherein the compression coefficient is the ratio of the envelope amplitude value of the in-phase and quadrature signals after peak clipping to the envelope amplitude value of the in-phase and quadrature signals before peak clipping; determine the in-phase component after reduction as the product of the in-phase component before reduction and the compression coefficient; determine the quadrature component after reduction as the product of the quadrature component before reduction and the compression coefficient.

[0117] In one embodiment of the present application, the calculation module 501 is configured to query a predetermined conversion table based on the envelope amplitude value of the in-phase and quadrature signals before peak clipping, and the envelope amplitude value of the in-phase and quadrature signals after peak clipping; wherein the conversion table includes: a value interval of the envelope amplitude value of the in-phase and quadrature signals before peak clipping, and the envelope amplitude value of the in-phase and quadrature signals after peak clipping corresponding to the value interval, and the value interval is determined by the derivative of the peak clipping function.

[0118] In one embodiment of the present application, the compression module 502 is configured to divide the values ​​of the independent variable of the peak clipping function into multiple value intervals based on the derivative of the peak clipping function; calculate the envelope amplitude value of the in-phase and orthogonal signals after peak clipping corresponding to each value interval based on the value interval and the peak clipping function; generate the conversion table based on the value interval and the envelope amplitude value of the in-phase and orthogonal signals after peak clipping; wherein the value interval includes: a linear region, a transition region and a saturation region; in the linear region, the difference between the derivative of the peak clipping function and 1 is less than a preset first threshold, and in the saturation region, the derivative of the peak clipping function is less than a preset second threshold; in the linear region, the transition region and the saturation region, the derivative of the peak clipping function decreases successively.

[0119] like Figure 6 The figure shows a schematic diagram of the OFDM transmission system architecture. The soft peak clipping device for suppressing the peak-to-average ratio of OFDM provided in the aforementioned embodiment is located in the peak-to-average ratio suppression module. The module value calculation refers to calculating the envelope amplitude value of the in-phase and quadrature signals based on the in-phase and quadrature components of the in-phase and quadrature signals obtained by OFDM modulation. Soft peak clipping refers to calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude value of the in-phase and quadrature signals; and reducing the in-phase and quadrature components based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping.

[0120] An embodiment of the present application provides a computer program product, including a computer program / instruction. When the computer program / instruction is executed by a processor, the method described in any of the above embodiments is implemented.

[0121] An embodiment of the present application provides a non-transitory computer-readable storage medium having computer-executable instructions stored thereon. When the computer-executable instructions are executed by a processor, the method described in any of the above embodiments is implemented.

[0122] Furthermore, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present application having equivalent elements, modifications, omissions, combinations (e.g., solutions that overlap various embodiments), adaptations, or changes. Although several embodiments are described separately for a wireless communication method and a wireless communication component, it should be noted that the method details described in the wireless communication component description can also be incorporated into various embodiments of the wireless communication method, and vice versa.

[0123] The elements of the claims are to be interpreted broadly based on the language employed in the claims and not limited to the examples described in this specification or during the prosecution of the application, which examples are to be construed as non-exclusive. Accordingly, it is intended that the specification and examples be considered as examples only, with the true scope and spirit being indicated by the claims and their full scope of equivalents.

[0124] The order of the steps in this application is merely exemplary and non-restrictive. The order of the steps may be adjusted without affecting the implementation of this application (without disrupting the required logical relationships between the steps), and the resulting embodiments will still fall within the scope of this application.

[0125] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more of their solutions) can be used in combination with each other. For example, those of ordinary skill in the art may use other embodiments when reading the above description. In addition, in the above-mentioned specific embodiments, various features can be grouped together to simplify the application. This should not be interpreted as an intention that a disclosed feature that is not required to be protected is necessary for any claim. On the contrary, the subject matter of the present invention may be less than all the features of a specific disclosed embodiment. Thus, the claims are incorporated into the specific embodiments as examples or embodiments, wherein each claim is independently a separate embodiment, and it is considered that these embodiments can be combined with each other in various combinations or arrangements. The scope of the present invention should be determined with reference to the appended claims and the full scope of equivalents to which these claims are entitled.

Claims

1. A soft peak clipping method for suppressing peak-to-average ratio in OFDM, characterized in that: include: Calculating the envelope amplitude value of the in-phase and quadrature signals based on the in-phase and quadrature components of the in-phase and quadrature signals obtained by orthogonal frequency division multiplexing (OFDM) modulation; Calculating the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals; wherein the peak clipping function is determined by a peak clipping threshold and a basis function, the independent variable of the peak clipping function is the envelope amplitude value of the in-phase and quadrature signals before peak clipping, and the dependent variable is the envelope amplitude value of the in-phase and quadrature signals after peak clipping; the peak clipping threshold is determined by a peak-to-average ratio, and the basis function includes any one of a Rapp model function, a Logistic function, and an inverse tangent function; The in-phase component and the quadrature component are reduced based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping.

2. The method according to claim 1, wherein in, The basic function is a Rapp model function; The peak clipping function is: Among them, a(n) is used to represent the envelope amplitude value of the in-phase and quadrature signals before peak clipping. It is used to characterize the envelope amplitude value of the in-phase and quadrature signals after peak clipping, A is used to characterize the peak clipping threshold, and p is used to characterize the peak clipping parameter, which is determined by the spectrum emission template and the error vector amplitude.

3. The method according to claim 1, wherein in, The basic function is a logistic function; Calculating the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals includes: In response to the envelope amplitude value of the in-phase and quadrature signals before peak clipping being greater than a first threshold, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping based on the peak clipping function and the envelope amplitude value of the in-phase and quadrature signals; Wherein, the peak clipping function includes: Among them, a(n) is used to represent the envelope amplitude value of the in-phase and quadrature signals before peak clipping. Used to characterize the envelope amplitude value of the in-phase and orthogonal signals after peak clipping, A is used to characterize the peak clipping threshold, k is used to characterize the first parameter, the first parameter is determined by the spectrum emission template and the error vector magnitude, c is used to characterize the second parameter, and the second parameter is calculated by the peak clipping threshold, the first threshold and the first parameter.

4. The method according to claim 1, wherein in, The basic function is an inverse tangent function; Calculating the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals includes: In response to the envelope amplitude value of the in-phase and quadrature signals before peak clipping being greater than a second threshold, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping based on the peak clipping function and the envelope amplitude value of the in-phase and quadrature signals; Wherein, the peak clipping function includes: Among them, a(n) is used to represent the envelope amplitude value of the in-phase and quadrature signals before peak clipping. It is used to characterize the envelope amplitude value of the in-phase and quadrature signals after peak clipping, A is used to characterize the peak clipping threshold, k a It is used to characterize a third parameter, where the third parameter is determined by a spectrum emission template and an error vector magnitude (EVM). A1 is used to characterize the second threshold.

5. The method according to claim 1, wherein The method reduces the in-phase component and the quadrature component based on envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping, comprising: Calculating a compression coefficient based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping; wherein the compression coefficient is the ratio of the envelope amplitude value of the in-phase and quadrature signals after peak clipping to the envelope amplitude value of the in-phase and quadrature signals before peak clipping; Determine the in-phase component after reduction as the product of the in-phase component before reduction and the compression coefficient; The orthogonal component after reduction is determined to be the product of the orthogonal component before reduction and the compression coefficient.

6. The method according to claim 1, wherein Calculating the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals includes: Based on the envelope amplitude values ​​of the in-phase and quadrature signals before peak clipping, a predetermined conversion table is queried to obtain the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping; wherein the conversion table includes: a value interval of the envelope amplitude values ​​of the in-phase and quadrature signals before peak clipping, and the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping corresponding to the value interval, and the value interval is determined by the derivative of the peak clipping function.

7. The method according to claim 6, wherein Further including: Based on the derivative of the peak clipping function, dividing the value of the independent variable of the peak clipping function into a plurality of value intervals; Based on the value intervals and the peak clipping function, calculating the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping corresponding to each of the value intervals; generating the conversion table based on the value interval and the corresponding envelope amplitude value of the in-phase and quadrature signals after peak clipping; The value range includes: a linear region, a transition region and a saturation region; in the linear region, the difference between the derivative of the peak clipping function and 1 is less than a preset first threshold; in the saturation region, the derivative of the peak clipping function is less than a preset second threshold; in the linear region, the transition region and the saturation region, the derivative of the peak clipping function decreases successively.

8. A soft peak clipping device for suppressing peak-to-average ratio in OFDM, characterized in that: include: A calculation module is configured to calculate the envelope amplitude value of the in-phase and quadrature signals based on the in-phase and quadrature components of the in-phase and quadrature signals obtained by OFDM modulation; Calculating the envelope amplitude values ​​of the in-phase and quadrature signals after peak clipping based on a preset peak clipping function and the envelope amplitude values ​​of the in-phase and quadrature signals; wherein the peak clipping function is determined by a peak clipping threshold and a basis function, the independent variable of the peak clipping function is the envelope amplitude value of the in-phase and quadrature signals before peak clipping, and the dependent variable is the envelope amplitude value of the in-phase and quadrature signals after peak clipping; the peak clipping threshold is determined by a peak-to-average ratio, and the basis function includes any one of a Rapp model function, a Logistic function, and an inverse tangent function; The compression module is configured to reduce the in-phase component and the quadrature component based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping.

9. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the method according to any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium having computer-executable instructions stored thereon, characterized in that: When the computer-executable instructions are executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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