Soft peak clipping method and device for suppressing peak-to-average ratio for OFDM (Orthogonal Frequency Division Multiplexing)

Abstract

The invention relates to a soft peak clipping method and device for suppressing a peak-to-average ratio for OFDM (Orthogonal Frequency Division Multiplexing), and relates to the technical field of signal processing, the method comprises the following steps: calculating an envelope amplitude value of an in-phase orthogonal signal based on an in-phase component and an orthogonal component of the in-phase orthogonal signal obtained by OFDM modulation; based on a preset peak clipping function and the envelope amplitude value of the in-phase orthogonal signal, calculating the envelope amplitude value of the in-phase orthogonal signal after peak clipping; wherein the peak clipping function is determined by a peak clipping threshold and a basic function, the peak clipping threshold is determined by a peak-to-average ratio, and the basic function comprises any one of an Rapp model function, a Rogowski function and an arc tangent function; the in-phase component and the quadrature component are reduced based on the envelope amplitude values of the in-phase quadrature signal before and after peak clipping. According to the method and the device, the OFDM signal after peak clipping can meet the requirement of a spectrum emission template on the premise of ensuring that the error vector amplitude performance meets the requirement.

Description

Technical Field

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

[0002] In the transmitting end of a broadband communication system, OFDM (Orthogonal Frequency Division Multiplexing) signals have a high peak-to-average power ratio (PAPR), which affects the performance of nonlinear devices, especially power amplifiers, during signal transmission, exacerbating the nonlinear distortion of the transmitted signal or causing a reduction in system power efficiency. Therefore, reducing the PAPR of OFDM signals is crucial to 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 will lead to enhanced out-of-band radiation, making the OFDM signal after peak clipping unable to meet the requirements of the spectrum emission template. Summary of the invention

[0005] The present application is provided to solve the above problems existing in the prior art. According to a soft peak clipping method and device for suppressing peak-to-average ratio for OFDM according to an embodiment of the present application, it is possible to ensure that the OFDM signal after peak clipping meets the requirements of the spectrum transmission template under the premise 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] Based on the in-phase component and the orthogonal component of the in-phase and orthogonal signals obtained by orthogonal frequency division multiplexing OFDM modulation, calculating the envelope amplitude value of the in-phase and orthogonal signals;

[0008] Based on a preset peak clipping function and the envelope amplitude value of the in-phase and quadrature signals, the envelope amplitude value of the in-phase and quadrature signals after peak clipping is calculated; wherein 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, 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 basic 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 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, 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 basic 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 a method as described in any of the above embodiments.

[0014] In a fourth aspect, an embodiment of the present application provides a non-temporary 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 embodiment of the present application is that: based on the peak clipping function, the OFDM signal is softly clipped, which can ensure that the error vector amplitude performance meets the requirements, so that the OFDM signal after peak clipping meets the requirements of the spectrum transmission template. Compared with hard peak clipping, the soft peak clipping solution provided in the embodiment of the present application can achieve smoother peak compression and greatly improve the signal spectrum performance after peak clipping. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar parts in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar parts. The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the specification and claims, are used to illustrate the disclosed embodiments. When 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 embodiments of the present apparatus or method.

[0017] Figure 1It 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 is a different peak clipping function curve provided by an embodiment of the present application;

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

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

[0021] Figure 5 It 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] In order 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 the present application are only intended to distinguish the corresponding features, do not represent the need for such an order, and do not 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, and is applicable to HT (High Throughput), VHT (Very High Throughput), HE (High Efficiency) and other signal standards in WLAN.

[0027] In order to ensure that the error vector amplitude of the signal after soft clipping meets the transmission requirements, this method is applicable to the transmission mode with an MCS (Modulation and Coding Scheme) value not exceeding 5. For example, in the 1x1HT scenario, the corresponding modulation mode is 64-QAM and the code rate is 2 / 3; for a bandwidth 20M signal, the corresponding transmission rate does not exceed 57.8Mbps; for a bandwidth 40M 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, 64-point quadrature amplitude modulation). The modulation modes that meet this condition include: BPSK (Binary Phase Shift Keying, binary phase shift keying), QPSK (QuadraturePhase Shift Keying, four-phase shift keying), 16-QAM (16-Quadrature Amplitude Modulation, 16-point quadrature amplitude modulation) and 64-QAM, etc.

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

[0030]

[0031] Among them, 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 value 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 characterize the envelope amplitude value of the in-phase and quadrature signals after peak clipping. M is used to characterize the maximum value of the absolute value of the in-phase component and the absolute value of the quadrature component. m is used to characterize the minimum value of the absolute value of the in-phase component and the absolute value of the quadrature component.

[0035] CORDIC (Coordinate Rotation Digital Computer) can also be used to calculate the envelope amplitude value 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 the linear approximation, and the phase value can be obtained while calculating the amplitude.

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

[0037] Step 102: Based on a 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.

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

[0039] The smaller the peak clipping threshold is, the smaller the peak-to-average ratio of the signal after peak clipping is. Therefore, the peak clipping threshold can be set based on the peak-to-average ratio requirement. Furthermore, since the smaller the peak-to-average ratio is, the worse the spectrum emission template and error vector magnitude performance is, the peak clipping threshold can be set based on the peak-to-average ratio, the spectrum emission template and the error vector magnitude. Therefore, under the premise of ensuring that the spectrum emission template and the error vector magnitude meet the transmission signal standard, the lower the peak clipping threshold is set, 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) approximate the hard peak clipping function to ensure the peak clipping performance; (2) have good continuity to reduce the 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] The embodiment of the present application performs soft peak clipping on the OFDM signal based on the peak clipping function, which can ensure that the error vector amplitude performance meets the requirements, so that the OFDM signal after peak clipping meets the requirements of the spectrum transmission template. Compared with hard peak clipping, the soft peak clipping solution provided in the embodiment of the present application can achieve smoother peak compression and greatly improve the signal spectrum performance after peak clipping.

[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 characterize 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 amplitude.

[0048] The smaller p is, the more obvious the peak-to-average ratio suppression effect is, the better the spectrum emission template margin is, but the error vector magnitude deteriorates more seriously. The p value range is [1,8]. In the embodiment of the present application, when p=2, the peak-to-average ratio, spectrum emission template and error vector magnitude can be well taken into account.

[0049] The embodiment of the present application obtains a peak clipping function by deforming the Rapp model function. The peak clipping function has good continuity and is close to the peak clipping threshold, which can reduce out-of-band radiation. At the same time, the peak clipping parameters can be adjusted based on the peak-to-average ratio of the peak clipped signal, the spectrum emission template and the error vector amplitude requirements 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 value of the in-phase and quadrature signals, the envelope amplitude value of the in-phase and quadrature signals after peak clipping is 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, based on the peak clipping function and the envelope amplitude value of the in-phase and quadrature signals, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping;

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

[0054]

[0055] Among them, a(n) is used to characterize 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 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 amplitude, and c is used to characterize the second parameter, which is calculated by the peak clipping threshold, the first threshold and the first parameter.

[0056] In response to the envelope amplitude value of the in-phase orthogonal signal before peak clipping being not greater than the first threshold, the envelope amplitude values ​​of the in-phase orthogonal signal before and after peak clipping are the same, that is, soft peak clipping is not performed on the in-phase orthogonal signal whose envelope amplitude value is not greater than the first threshold. Based on this, the method further includes: in response to the envelope amplitude value of the in-phase orthogonal signal before peak clipping being not greater than the first threshold, terminating the current process.

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

[0058]

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

[0060] It should be noted that in actual application scenarios, equations (4) and (5) can be transformed, that is, the peak clipping function obtained based on the logistic function can have different forms. For example, there is no first parameter in equation (5), that is, the calculation of the second parameter is independent of the first parameter. The first parameter is only determined 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 template and error vector amplitude performance. The value of k is [0,8]. The smaller the value of k, the better the peak-to-average ratio suppression effect, but the worse the spectrum emission template and error vector amplitude performance. In the embodiment of the present application, A0 is three quarters of A, and k is 4.

[0062] The peak clipping function obtained by the logistic function has good continuity and is close to the peak clipping threshold, which can reduce out-of-band radiation. At the same time, the first parameter can be adjusted based on the requirements of the spectrum emission template and the error vector amplitude to meet the needs of different scenarios. The in-phase orthogonal signals that need to be clipped can be screened out by the first threshold, reducing the amount of peak clipping calculation.

[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 value of the in-phase and quadrature signals, the envelope amplitude value of the in-phase and quadrature signals after peak clipping is 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, based on the peak clipping function and the envelope amplitude value of the in-phase and quadrature signals, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping;

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

[0067]

[0068] Among them, a(n) is used to characterize 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 the third parameter, which is determined by the spectrum emission template and the error vector amplitude. A1 is used to characterize the second threshold.

[0069] In response to the envelope amplitude value of the in-phase orthogonal signal before peak clipping being not greater than the second threshold, the envelope amplitude values ​​of the in-phase orthogonal signal before and after peak clipping are the same, that is, soft peak clipping is not performed on the in-phase orthogonal signal whose envelope amplitude value is not greater than the second threshold. Based on this, the method further includes: in response to the envelope amplitude value of the in-phase orthogonal signal before peak clipping being not greater than the second threshold, terminating the current process.

[0070] The peak clipping function based on the inverse tangent function may be in other forms, such as 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 template and error vector amplitude performance. The value of k is [0,4]. The smaller the value of k, the better the peak-to-average ratio suppression effect, but the worse the spectrum emission template and error vector amplitude performance. In the embodiment of the present application, A1 is three quarters of A, and k is 2.

[0072] The peak clipping function obtained by the inverse tangent function has good continuity and is close to the peak clipping threshold, which can reduce out-of-band radiation. At the same time, the third parameter can be adjusted based on the requirements of the spectrum emission template and the error vector amplitude to meet the needs of different scenarios. The in-phase and orthogonal signals that need to be clipped can be screened out by the second threshold to reduce the amount of peak clipping calculations.

[0073] like Figure 2 As shown in the figure, different peak clipping function curves are shown, with the horizontal axis representing the normalized input amplitude value and the vertical axis representing the normalized output amplitude value. Hard clipping is a hard peak clipping function curve; rapp refers to the Rapp model function, and the peak clipping parameters of the two Rapp model function curves are 2 and 6 respectively; logistic-based refers to the peak clipping function obtained based on the logistic function; arctan-based refers to the peak clipping function obtained based on the inverse tangent function.

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

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

[0076] Determine that the in-phase component after reduction is 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 orthogonal 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 value of the in-phase and quadrature signals, the envelope amplitude value of the in-phase and quadrature signals after peak clipping is calculated, including:

[0080] Based on the envelope amplitude value of the in-phase orthogonal signal before peak clipping, a predetermined conversion table is queried to obtain the envelope amplitude value of the in-phase orthogonal signal after peak clipping; wherein the conversion table contains: a value interval of the envelope amplitude value of the in-phase orthogonal signal before peak clipping, and the envelope amplitude value of the in-phase orthogonal signal 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 is calculated using the peak clipping function, which consumes a lot of hardware, the embodiment of the present application pre-establishes a conversion table based on the peak clipping function, and can query the conversion table based on the envelope amplitude value of the in-phase orthogonal signal before peak clipping to obtain the envelope amplitude value of the in-phase orthogonal signal after peak clipping. This table lookup method does not require complex calculations and consumes little 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 orthogonal signal after peak clipping corresponding to each value interval based on the value interval and the peak clipping function; generating a conversion table based on the value interval and the corresponding envelope amplitude value of the in-phase orthogonal signal 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 requirements of the actual business scenario. For example, the first threshold is 0.01 and the second threshold is 0.1.

[0085] like Figure 3 As shown, the horizontal axis is the normalized input amplitude value, which is the envelope amplitude value of the in-phase orthogonal signal before peak clipping, and the vertical axis is the normalized output amplitude value, which is the envelope amplitude value of the in-phase orthogonal signal after peak clipping. S1 is the boundary value between the linear region and the transition region, and S2 is the boundary value 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 the accuracy of the query, the transition region can be further divided into H sub-intervals. The value of the peak clipping function is calculated based on the midpoint of each sub-interval, so as to obtain the envelope amplitude value of the in-phase orthogonal signal after peak clipping corresponding to each sub-interval. 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, and 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 the normalized 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 sub-intervals 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 sub-intervals 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 peak clipping method provided by the above embodiment can reduce power consumption, because the low-order modulated OFDM signal after soft peak clipping has a low peak-to-average ratio characteristic under the premise of meeting the transmission conditions, and the power amplifier can work in a near-saturation region, with higher power added efficiency, which can effectively reduce the working power. At the same time, compared with hard peak clipping, soft peak clipping has a smoother peak clipping function, and can effectively reduce the out-of-band radiation component under the premise of ensuring that the error vector amplitude meets the requirements.

[0099] Taking the Rapp model function as an example, the peak-to-average ratio and error vector amplitude of different peak clipping conditions are shown in Table 3. As can be seen from Table 3, by ensuring that the error vector amplitude meets the low-order modulation signal transmission conditions, the peak-to-average ratio can be reduced from 9.3dB to 5.4dB through soft peak clipping, which will greatly improve the working efficiency of the power amplifier.

[0100] Table 3

[0101]

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

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

[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 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, including:

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

[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 orthogonal signals before and after peak clipping; wherein the compression coefficient is the ratio of the envelope amplitude value of the in-phase and orthogonal signals after peak clipping to the envelope amplitude value of the in-phase and orthogonal signals before peak clipping; determine that the in-phase component after reduction is the product of the in-phase component before reduction and the compression coefficient; determine that the orthogonal component after reduction is the product of the orthogonal 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 orthogonal signal before peak clipping, and the envelope amplitude value of the in-phase orthogonal signal after peak clipping; wherein the conversion table contains: a value interval of the envelope amplitude value of the in-phase orthogonal signal before peak clipping, and the envelope amplitude value of the in-phase orthogonal signal 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 value 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 orthogonal signal after peak clipping corresponding to each of the value intervals based on the value intervals and the peak clipping function; generate the conversion table based on the value intervals and the corresponding envelope amplitude values ​​of the in-phase orthogonal signal after peak clipping; wherein the value intervals include: 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 As shown, it is 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 above-mentioned 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 the preset peak clipping function and the envelope amplitude value of the in-phase and quadrature signals; based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping, reducing the in-phase component and the quadrature component.

[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 on which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, the method described in any of the above embodiments is implemented.

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

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

[0124] The order of each step in the present application is merely exemplary and not restrictive. Without affecting the implementation of the present application (without destroying the required logical relationship between the steps), the execution order of the steps can be adjusted, and the various embodiments obtained after the adjustment still fall within the scope of the present application.

[0125] The above description is intended to be illustrative rather than restrictive. For example, the above examples (or one or more of them) can be used in combination with each other. For example, those of ordinary skill in the art can 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 does not require protection 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 used as 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 attached claims and the full scope of equivalent forms granted by these claims.

Claims

1. A soft peak clipping method for suppressing peak-to-average ratio in OFDM, characterized in that: include: Based on the in-phase component and the orthogonal component of the in-phase and orthogonal signals obtained by orthogonal frequency division multiplexing OFDM modulation, calculating the envelope amplitude value of the in-phase and orthogonal signals; Based on a preset peak clipping function and the envelope amplitude value of the in-phase and quadrature signals, the envelope amplitude value of the in-phase and quadrature signals after peak clipping is calculated; wherein 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, 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 basic 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, characterized in that in, The basic function is a Rapp model function; The peak clipping function is: Among them, a(n) is used to characterize 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, characterized in that in, The basic function is a logistic function; 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, including: In response to the envelope amplitude value of the in-phase and quadrature signals before peak clipping being greater than a first threshold, based on the peak clipping function and the envelope amplitude value of the in-phase and quadrature signals, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping; Wherein, the peak clipping function includes: Among them, a(n) is used to characterize 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 amplitude, c is used to characterize the second parameter, the second parameter is calculated by the peak clipping threshold, the first threshold and the first parameter.

4. The method according to claim 1, characterized in that in, The basic function is an inverse tangent function; 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, including: In response to the envelope amplitude value of the in-phase and quadrature signals before peak clipping being greater than a second threshold, based on the peak clipping function and the envelope amplitude value of the in-phase and quadrature signals, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping; Wherein, the peak clipping function includes: Among them, a(n) is used to characterize 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, and A1 is used to characterize the second threshold.

5. The method according to claim 1, characterized in that Based on the envelope amplitude values ​​of the in-phase and quadrature signals before and after peak clipping, reducing the in-phase component and the quadrature component, comprising: Calculating a compression coefficient based on the envelope amplitude values ​​of the in-phase orthogonal signals before and after peak clipping; wherein the compression coefficient is the ratio of the envelope amplitude value of the in-phase orthogonal signals after peak clipping to the envelope amplitude value of the in-phase orthogonal 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, characterized in that 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, including: Based on the envelope amplitude value of the in-phase and orthogonal signals before peak clipping, a predetermined conversion table is queried to obtain the envelope amplitude value of the in-phase and orthogonal signals after peak clipping; wherein the conversion table contains: a value interval of the envelope amplitude value of the in-phase and orthogonal signals before peak clipping, and the envelope amplitude value of the in-phase and orthogonal 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, characterized in that 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 interval and the peak clipping function, calculating the envelope amplitude value of the in-phase and quadrature signals after peak clipping corresponding to each of the value intervals; Generate the conversion table based on the value interval and the corresponding envelope amplitude value of the in-phase and quadrature signals after peak clipping; Wherein, 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.

8. A soft peak clipping device for suppressing peak-to-average ratio in OFDM, characterized in that: include: A calculation module, 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; Based on a preset peak clipping function and the envelope amplitude value of the in-phase and quadrature signals, the envelope amplitude value of the in-phase and quadrature signals after peak clipping is calculated; wherein 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, 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 basic 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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