WO2017214998A1

WO2017214998A1 - Clipping method and device for orthogonal frequency division multiplexing

Info

Publication number: WO2017214998A1
Application number: PCT/CN2016/086288
Authority: WO
Inventors: 张胜波
Original assignee: 华为技术有限公司
Priority date: 2016-06-17
Filing date: 2016-06-17
Publication date: 2017-12-21
Also published as: CN109155769A; CN109155769B

Abstract

Disclosed are a clipping method and device for orthogonal frequency division multiplexing. The method comprises: receiving an original time domain signal; clipping the original time domain signal based on a pre-set clipping threshold to obtain a peak clipping signal; compensating for the peak clipping signal based on a pre-set noise compensation threshold to obtain compensated noise, wherein the noise compensation threshold is less than the clipping threshold; superposing the peak clipping signal delayed by a second time and the compensated noise in a forward manner to obtain comprehensive peak clipping noise, wherein the product of a virtual subcarrier transform matrix corresponding to the original time domain signal and the comprehensive peak clipping noise is zero; and superposing the comprehensive peak clipping noise onto the original time domain signal delayed by a first time in a reverse manner to obtain an output signal. By implementing the embodiments of the present invention, it is possible to ensure that a signal obtained after an original time domain signal is clipped falls more probably below a clipping threshold.

Description

Orthogonal frequency division multiplexing clipping method and device

Technical field

The present invention relates to the field of communications, and in particular, to a method and device for clipping of orthogonal frequency division multiplexing.

Background technique

Orthogonal Frequency Division Multiplexing (OFDM) modulation technology divides the channel into several orthogonal subchannels, so that the information to be transmitted is carried on the subchannel, which greatly improves the spectrum utilization and adds a cyclic prefix. The inter-OFDM interference is removed, and the inter-subcarrier interference is also effectively resisted. At the same time, each subchannel is smaller than the relevant bandwidth of the channel, so that the subchannel is flat fading, which greatly simplifies the demodulation at the receiving end. OFDM technology has been widely used in wireless communication systems such as digital broadcasting, wireless local area network, Long Term Evolution (LTE) and advanced LTE (LTE-A), and will be used in the fifth generation mobile communication system ( The fifth generation, 5G) continues to be used. When the number of subcarriers in OFDM is relatively large (the number of subcarriers in an actual communication system is usually hundreds or thousands), the OFDM time domain signal approximates a complex Gaussian distribution, which leads to an inherent disadvantage of the OFDM system: power peak-to-average ratio (Peak-average Power Ratio, PAPR) is too high. When a high PAPR signal passes through a power amplifier (PA), in order to avoid nonlinear distortion of the signal and out-of-band spectrum regeneration, the PA must be left with a large power back-off, thereby reducing the efficiency of the power amplifier, so reducing the power peak of the signal. On average, it is valuable for almost all OFDM systems. In order to avoid nonlinear distortion and out-of-band spectral reproduction of OFDM signals, the prior art provides a Peak-Cancellation (PC) technology, which extracts the portion of the time domain signal that exceeds the threshold according to a threshold. The peak value is then preserved by filtering or time-frequency transform to preserve the component of the peak signal within the effective bandwidth, and finally reversely superimposed on the original signal to achieve the effect of canceling the peak.

The inverse superimposed signals of the existing PC technology are randomly generated, and the spectrum thereof is also random, so the PAPR of the OFDM signal processed by the PC technology is uncontrollable, resulting in poor clipping effect.

Summary of the invention

The embodiment of the invention discloses a method and a device for clipping of orthogonal frequency division multiplexing, which can ensure that the signal obtained by the original time domain signal after clipping processing falls below the clipping threshold with greater probability.

In a first aspect, an embodiment of the present invention provides a clipping method for orthogonal frequency division multiplexing, where the method includes:

Receiving the original time domain signal;

And cutting the original time domain signal according to a preset clipping threshold to obtain a peak clipping signal;

Performing compensation processing on the peak clipping signal according to a preset compensation noise threshold, wherein the compensation noise threshold is less than the clipping threshold;

The peak clipping signal delayed by the second time is forwardly superimposed with the compensation noise to obtain integrated peaking noise, wherein the product of the virtual subcarrier transformation matrix corresponding to the original time domain signal and the integrated peaking noise is zero;

The integrated peaking noise is inversely superimposed to the original time domain signal delayed by the first time to obtain an output signal.

By performing the above steps, the device calculates the peak clipping signal and the compensation noise of the original time domain signal, and superimposes the peak clipping signal and the compensation noise as a comprehensive peak clipping noise, and finally superimposes the integrated peak clipping noise. The original time domain signal is obtained to obtain an output signal such that the output signal remains at a high probability below the clipping threshold.

With reference to the first aspect, in a first possible implementation manner of the first aspect, the original time domain signal is obtained by N time slots in the frequency domain by N times time domain sampling points obtained by inverse discrete Fourier transform IDFT Signal composition, the calculation rule of the peak clipping signal of the signal at the nth time domain sampling point of the N time domain sampling points is: the amplitude of the signal at the nth time domain sampling point When the clipping threshold is less than or equal to, the peak clipping signal of the signal at the nth time domain sampling point is equal to zero; when the amplitude of the signal at the nth time domain sampling point is greater than the clipping threshold The calculation formula of the peak clipping signal is: p ₁ (n)=x(n)*(1-T1/|x(n)|), where p ₁ (n) represents the nth time domain sampling point The peak clipping signal of the signal, T1 is the clipping threshold, x(n) represents the signal at the nth time domain sampling point, and the n clipping peaks obtained by sequentially taking n values from 1 to N The set of signals is the clipping signal of the original time domain signal.

With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner of the first aspect, when the amplitude of the signal at the nth time domain sampling point is greater than or equal to the compensation noise gate The time-limited, the compensation noise of the signal at the nth time domain sampling point is equal to zero; when the amplitude of the signal at the nth time domain sampling point is less than the compensation noise threshold, the nth time domain The compensation noise of the signal at the sampling point takes the value of one element in the equivalent short vector, and the compensation noise of the signal at any two time domain sampling points does not take the value of the same element in the equivalent short vector; The formula for calculating the equivalent short vector is:

among them,

Representing the equivalent short vector, p ₁ represents a clipping signal of the original time domain signal, W ₁ is a virtual subcarrier transformation matrix corresponding to the original time domain signal, and W ₁₂ is an element of a partial column in W ₁ ,

for

Conjugate transposition.

With reference to the second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, the W is to transform the original time domain signal belonging to the discrete time from the time domain to the discrete frequency in the frequency domain. A kernel transformation matrix, W ₁ is a matrix composed of partial rows in W, and the matrix formed by the partial rows corresponds to virtual subcarriers in W.

With reference to the first aspect, or the first possible implementation of the first aspect, or the second possible implementation of the first aspect, or the third possible implementation of the first aspect, in the first aspect In four possible implementation manners, the first time is greater than the second time.

In a second aspect, an embodiment of the present invention provides a device, where the device includes a processor, a memory, and a transceiver, where the memory is used to store a program, and the processor invokes a program in the memory for execution. Do the following:

Receiving an original time domain signal through the transceiver;

By performing the above operation, the device calculates the peak clipping signal and the compensation noise of the original time domain signal, and superimposes the peak clipping signal and the compensation noise as a comprehensive peak clipping noise, and finally the comprehensive The peak-shaping noise is inversely superimposed on the original time domain signal to obtain an output signal such that the output signal remains at a high probability below the clipping threshold.

With reference to the second aspect, in a first possible implementation manner of the second aspect, the original time domain signal is obtained by N time slots in the frequency domain by N times time domain sampling points obtained by inverse discrete Fourier transform IDFT Signal composition, the calculation rule of the peak clipping signal of the signal at the nth time domain sampling point of the N time domain sampling points is: the amplitude of the signal at the nth time domain sampling point When the clipping threshold is less than or equal to, the peak clipping signal of the signal at the nth time domain sampling point is equal to zero; when the amplitude of the signal at the nth time domain sampling point is greater than the clipping threshold The calculation formula of the peak clipping signal is: p ₁ (n)=x(n)*(1-T1/|x(n)|), where p ₁ (n) represents the nth time domain sampling point The peak clipping signal of the signal, T1 is the clipping threshold, x(n) represents the signal at the nth time domain sampling point, and the n clipping peaks obtained by sequentially taking n values from 1 to N The set of signals is the clipping signal of the original time domain signal.

With reference to the first possible implementation manner of the second aspect, in a second possible implementation manner of the second aspect, when the amplitude of the signal at the nth time domain sampling point is greater than or equal to the compensation noise gate The time-limited, the compensation noise of the signal at the nth time domain sampling point is equal to zero; when the amplitude of the signal at the nth time domain sampling point is less than the compensation noise threshold, the nth time domain The compensation noise of the signal at the sampling point takes the value of one element in the equivalent short vector, and the compensation noise of the signal on any two subcarriers does not take the value of the same element in the equivalent short vector; The short vector is calculated as:

among them,

Representing the equivalent short vector, p ₁ represents a peak clipping signal of the original time domain signal, W ₁ is a virtual subcarrier transformation matrix corresponding to the original time domain signal, and W ₁₂ is a partial column of W ₁ element,

Transposed for conjugate of W ₁₂ .

With reference to the second possible implementation of the second aspect, in a third possible implementation manner of the second aspect, the W is to transform the original time domain signal belonging to the discrete time signal from the time domain to the frequency domain. A Fourier transform matrix, W ₁ is a matrix composed of partial rows in W, and the matrix formed by the partial rows corresponds to virtual subcarriers in W.

With reference to the second aspect, or the first possible implementation of the second aspect, or the second possible implementation of the second aspect, or the third possible implementation of the second aspect, in the second aspect In a fourth possible implementation manner, the first time is greater than the second time.

In a third aspect, an embodiment of the present invention provides a device, where the device includes:

a receiving unit, configured to receive an original time domain signal;

a clipping unit, configured to perform clipping processing on the original time domain signal according to a preset clipping threshold to obtain a peak clipping signal;

a compensation unit, configured to perform compensation processing on the peak clipping signal according to a preset compensation noise threshold, where the compensation noise threshold is less than the clipping threshold;

a calculating unit, configured to positively superimpose the peak clipping signal delayed by the second time and the compensation noise to obtain a comprehensive peak clipping noise, wherein a product of the virtual subcarrier transformation matrix corresponding to the original time domain signal and the integrated peak clipping noise is zero;

And a superimposing unit, configured to inversely superimpose the integrated peaking noise to the original time domain signal delayed by the first time to obtain an output signal.

By running the above unit, the device calculates the peak clipping signal and the compensation noise of the original time domain signal, and superimposes the peak clipping signal and the compensation noise as a comprehensive peak clipping noise, and finally superimposes the integrated peak clipping noise. The original time domain signal is obtained to obtain an output signal such that the output signal remains at a high probability below the clipping threshold.

With reference to the third aspect, in a first possible implementation manner of the third aspect, the original time domain signal is obtained by N time slots on the frequency domain by N discrete time Fourier transform IDFT Signal composition, the calculation rule of the peak clipping signal of the signal at the nth time domain sampling point of the N time domain sampling points is: the amplitude of the signal at the nth time domain sampling point When the clipping threshold is less than or equal to, the peak clipping signal of the signal at the nth time domain sampling point is equal to zero; when the amplitude of the signal at the nth time domain sampling point is greater than the clipping threshold The calculation formula of the peak clipping signal is: p ₁ (n)=x(n)*(1-T1/|x(n)|), where p ₁ (n) represents the nth time domain sampling point The peak clipping signal of the signal, T1 is the clipping threshold, x(n) is a signal indicating the signal at the nth time domain sampling point, and the n is sequentially obtained from 1 to N. The set of peak signals is the clipping signal of the original time domain signal.

With reference to the first possible implementation manner of the third aspect, in a second possible implementation manner of the third aspect, when the amplitude of the signal at the nth time domain sampling point is greater than or equal to the compensation noise gate The time-limited, the compensation noise of the signal at the nth time domain sampling point is equal to zero; when the amplitude of the signal at the nth time domain sampling point is less than the compensation noise threshold, the nth time domain The compensation noise of the signal at the sampling point takes the value of one element in the equivalent short vector, and the compensation noise of the signal at any two time domain sampling points does not take the value of the same element in the equivalent short vector; The formula for calculating the equivalent short vector is:

among them,

To represent the equivalent short vector, p ₁ is a peak clipping signal representing the original time domain signal, W ₁ is a virtual subcarrier transformation matrix corresponding to the original time domain signal, and W ₁₂ is a partial column in W ₁ Elements,

Transposed for conjugate of W ₁₂ .

With reference to the second possible implementation manner of the third aspect, in a third possible implementation manner of the third aspect, the W is to transform the original time domain signal belonging to the discrete time signal from the time domain to the frequency domain. A Fourier transform matrix, W ₁ is a matrix composed of partial rows in W, and the matrix formed by the partial rows corresponds to virtual subcarriers in W.

With reference to the third aspect, or the first possible implementation of the third aspect, or the second possible implementation of the third aspect, or the third possible implementation of the third aspect, in the third aspect In four possible implementation manners, the first time is greater than the second time.

By implementing the embodiment of the present invention, the device calculates a peak clipping signal and a compensation noise of the original time domain signal, and superimposes the peak clipping signal and the compensation noise as a comprehensive peak clipping noise, and finally inverses the integrated peak clipping noise. The original time domain signal is superimposed to obtain an output signal such that the output signal remains at a high probability below the clipping threshold.

DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without paying any creative work.

1 is a flowchart of a method for clipping of orthogonal frequency division multiplexing according to an embodiment of the present invention;

2A is a schematic diagram of a scenario of clipping processing and compensation processing according to an embodiment of the present invention;

2B is a schematic diagram of an original time domain signal according to an embodiment of the present invention;

2C is a schematic diagram of a clipping process on an original time domain signal according to an embodiment of the present invention;

3A is a schematic diagram of a peak clipping signal according to an embodiment of the present invention;

FIG. 3B is a schematic diagram of compensation noise according to an embodiment of the present invention; FIG.

4 is a schematic structural diagram of an apparatus according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of still another apparatus according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described in the following with reference to the accompanying drawings.

The device described in the embodiments of the present invention may be a digital broadcast transmitter, a digital broadcast receiver, a wireless fidelity (WiFi) node in a wireless local area network, or a base station base station (evolved Node B) in a cellular mobile communication network. eNB), a mobile phone in a cellular mobile communication network, or the like that uses OFDM modulation technology.

Referring to FIG. 1 , FIG. 1 is a schematic flowchart of a method for clipping of an orthogonal frequency division multiplexing according to an embodiment of the present invention. The method is applied to processing an OFDM signal in an OFDM system, where the method includes but is not limited to The following steps:

Step 101: The device receives an original time domain signal.

Specifically, the original time domain signal is composed of signals on N time-domain sampling points obtained by inverse discrete Fourier transform IDFT of N subcarriers in the frequency domain, and the nth time of the N time domain sampling points The signal of the domain sampling point can be represented as x(n), then the original time domain signal is composed of the elements x(1), x(2), ..., x(N), and the original can be represented by the vector x. Time domain signal.

Since the device subsequently inversely superimposes the calculated integrated peaking noise and the original time domain signal, the original time domain signal needs to be continued for a period of time, in the embodiment of the present invention, by using the original time The domain signal is delayed for a first time to cause the original time domain signal to continue for a period of time. The size of the first time can be set in advance according to actual needs.

Step 102: The device performs clipping processing on the original time domain signal according to a preset clipping threshold. A peak clipping signal is obtained.

Specifically, since the original time domain signal is composed of signals on N time domain sampling points, it is necessary to perform clipping processing on the signals in each of the N time domain sampling points to obtain each time domain. The peak clipping signal of the sampling point, the set of peak clipping signals of each time domain sampling point is a peak clipping signal of the original time domain signal, and the peak clipping signal of the original time domain signal can be represented by a vector p ₁ .

p ₁ = (p ₁ (1), p ₁ (2), p ₁ (3), ..., p ₁ (n), ..., p ₁ (N)) ^T 1-1

In Equation 1-1, p ₁ represents the peak clipping signal of the original time domain signal, and p ₁ (n) represents the peak clipping signal of the nth time domain sampling point in the N time domain sampling points, n from 1 to The value of N is calculated as follows: p ₁ (n) is as follows:

In Equation 1-2, x(n) represents the signal at the nth time domain sampling point in the original time domain signal, T ₁ is the clipping threshold, and p ₁ (n) represents the nth time domain sampling point. The peak clipping signal, |x(n)| is the magnitude of x(n). The size of the clipping threshold T ₁ can be set in advance according to actual needs. It can be known from Equation 1-2 that when the amplitude of the signal at a certain time domain sampling point is less than or equal to T ₁ , the peak clipping signal of the certain time domain sampling point is equal to zero; when the signal at a certain time domain sampling point is When the amplitude is greater than T ₁ , the peak clipping signal of the certain time domain sampling point is equal to x(n)*(1-T1/|x(n)|).

Step 103: The device performs compensation processing on the peak clipping signal according to a preset compensation noise threshold to obtain compensation noise, wherein the compensation noise threshold is less than the clipping threshold.

Specifically, since the peak clipping signal of the original time domain signal is subsequently required to be superimposed with the compensation noise, the peak clipping signal of the original time domain signal needs to be continued for a period of time, in the embodiment of the present invention, by using the original time domain signal. The clipping signal is delayed by a second time to cause the peaking signal of the original time domain signal to continue for a period of time. The size of the second time may be preset according to actual needs. Optionally, the second time is less than the first time.

Further, compensation processing is performed on the signals in each time domain sampling point of the N time domain sampling points to obtain compensation noise of each time domain sampling point, and the set of compensation noise of each time domain sampling point is the original time. The compensation noise of the domain signal, the compensation noise of the original time domain signal can be represented by the vector p ₂ .

p ₂ = (p ₂ (1), p ₂ (2), p ₂ (3), ..., p ₂ (n), ..., p ₂ (N)) ^T 1-3

In Equations 1-3, p ₂ represents the compensation noise p ₂ (n) of the original time domain signal representing the compensation noise of the nth time domain sampling point among the N time domain sampling points, and when the nth When the amplitude of the signal at the time domain sampling point is greater than or equal to the compensation noise threshold T ₂ , the compensation noise p ₂ (n) of the signal at the nth time domain sampling point is equal to zero, when the nth When the amplitude of the signal at the domain sampling point is less than the compensation noise threshold T ₂ , the compensation noise p ₂ (n) of the signal at the nth time domain sampling point may not be zero. n takes values from 1 to N. The following describes how the p _{2 is} specifically determined:

From the above analysis, when | x (n) |> T 1 when, p ₁ (n) it may be zero, when | x (n) | <T 2 when, p ₂ (n) it may be non-zero, and Since T ₂ <T ₁ , when n takes a certain value, if p ₁ (n) is not zero, then p ₂ (n) is zero, and if p ₂ (n) is not zero, then p ₁ (n) is zero. Thus, p _₂ + p ₂ of the energy _{_{^{(p 1 + p 2) H}}} (p 1 + p 2) satisfies the following relationship:

(p ₁ +p ₂ ) ^H (p ₁ +p ₂ )=p ₁ ^H p ₁ +p ₂ ^H p ₂ 1-4

In the formula 1-4, p ₁ ^H represents a conjugate transposition of p ₁ , and p ₂ ^H represents a conjugate transposition of p ₂ . Since the energy of p ₁ +p ₂ is proportional to the square of the Error Vector Magnitude (EVM) of the clipped signal, the clipping should minimize the energy of p ₁ +p ₂ . Moreover, since the energy of p ₁ is determined when the original time domain signal and the clipping threshold T ₁ are determined, it can be known from the combination of Equations 1-4 that minimizing the energy of p ₁ +p ₂ is equivalent to minimizing p ₂ . energy.

In the embodiment of the present invention, p ₂ satisfies the following conditions:

Min p ₂ ^H p ₂

Satisfied: W ₁ (p ₁ +p ₂ )=0 1-5

In order to facilitate the understanding of Equations 1-5, a Discrete Fourier Transform (DFT) matrix W is first introduced. The matrix W is a transformation matrix that transforms discrete time signals from the time domain to the frequency domain. The original time domain signal is discrete. The time signal, W ₁ may be a sub-matrix of the matrix W, and multiple rows may be extracted from W to obtain W ₁ , and the extracted row corresponds to the position of the virtual sub-carrier in all sub-carriers, so W ₁ may also be referred to as virtual sub-carrier transformation. A matrix, the virtual subcarrier is a virtual subcarrier corresponding to the original time domain signal. Equation 1-5 specifically constrains the value of p ₂ by two conditions, where W ₁ (p ₁ +p ₂ )=0 is used to indicate the virtual subcarrier transformation matrix W ₁ and (p ₁ +p ₂ ) The product is zero, the purpose is to make the compensation noise p ₂ cancel the frequency component of the clipping signal p ₁ on the subcarrier that cannot be added, and there are many p ₂ that satisfy W ₁ *(p ₁ +p ₂ )=0, so further (p ₂ p ₂ ^H) satisfy the condition selected by the plurality of p ₂ min in ^H p ₂ p ₂ p ₂ is a minimum value.

1-5 can be obtained satisfies the equation p ₂ by the following method: first construct vector p ₂ is an equivalent short

p ₂ and

Satisfies the relationship, when | x (n) | ≥T ₂ p ₂ when the elements of p ₂ (n-) deleted is obtained

Where n is taken as 1, 2, 3, 4, ..., N; then the equivalent short vector is calculated by Equation 1-6

Calculate

Pushing the p _{2 again} , inserting the element p ₂ (n) corresponding to the value of zero into the

A new vector is formed, and the new vector is p ₂ .

In Equations 1-6,

For the equivalent short vector, p ₁ is a clipping signal of the original time domain signal, W ₁ is the virtual subcarrier transformation matrix, and W ₁₂ is a matrix composed of partial columns in W ₁ , when |x(n )|<T2, (n takes 1, 2, ..., N in order), the nth column of W ₁ is selected, and the elements of the partial column of W ₁₂ are obtained in order.

Transposed for conjugate of W ₁₂ .

That is, if _{| x (n) | ≥T 2} , p ₂ in the n-th element is zero, if | x (n) | <T 2 p in the n-th element ₂ p ₂ (n Equal to the equivalent short vector

The value of an element in , any two elements in p ₂ are not taken

The value of the same element in the middle, each element representing the compensation noise of a time domain sample point.

For example, N=16, except p ₂ (1)=0, p ₂ (2) to p ₂ (16) are not 0, and the calculated

Equal to (1,2,3,4,6,7,1,2,3,5,3,8,1,7,9), since the device knows the first time domain of the 16 time domain sampling points The compensation noise of the sample point is equal to 0, so the device inserts 0 into the

A new vector is formed, the first element in the new vector is equal to 0, so the new vector is (0,1,2,3,4,6,7,1,2,3,5,3,8 , 1, 7, 9), the obtained p ₂ is equal to (0,1,2,3,4,6,7,1,2,3,5,3,8,1,7,9).

Step 104: The device delays the result of the positive peaking of the peak clipping signal and the compensation noise in the second time as the integrated peak clipping noise.

Step 105: The device inversely superimposes the integrated peak clipping noise on the original time domain signal delayed by the first time to obtain an output signal. High probability amplitude of the output signal at the clipping threshold T ₁ or less.

It should be noted that the clipping threshold T ₁ can be determined according to the original time domain signal maximum amplitude max|x(n)| and the PAPR reduction target value, and the compensation noise threshold T _{2 is} lower than T _{1 by} a certain value (such as 0.5). dB, embodiments of the invention do not limit how much T _{2 is} lower than T ₁ ). When the clipping threshold T _{1 is} not excessively low (the value is related to a specific system), the maximum probability of the clipped signal x-(p ₁ + p ₂ ) does not exceed the clipping threshold T ₁ . If you ignore the small change in the total energy of the signal before and after clipping, use 20lg(max|x(n)|/T1) as the target value of the PAPR reduction, and take the 20M LTE system as an example. When all the effective subcarriers can be added, The PAPR reduction is less than 3dB+, or when the cell reference signal (Cell Reference Signal, CRS) and other non-noise pilots are included and the PAPR reduction is within 2dB+, the signal after clipping is x-(p ₁ +p ₂ ) The maximum value does not exceed the clipping threshold.

When a small probability event occurs, that is, the maximum amplitude of the signal after clipping exceeds T ₁ , x-(p ₁ +p ₂ ) is clipped to obtain clipping noise and transformed into the frequency domain according to the processing procedure similar to PC clipping. The component on the subcarrier that cannot be added with noise is set to zero, and the filtered clipping noise is obtained, and then inversely superimposed to x-(p ₁ +p ₂ ), which can effectively reduce the maximum amplitude of the signal after clipping.

The technical effects of the embodiments of the present invention will be described below based on actual examples with reference to the accompanying drawings.

In the above practical example, the Fast Fourier Transformation (FFT) points are 256, the effective subcarriers are 160, and the virtual subcarriers are 96.

2A is a schematic diagram of an application scenario of clipping processing and compensation processing. As shown in FIG. 2B, the original time domain signal has 256 points of FFT, as shown in FIG. 2B, and the first horizontal line is a clipping threshold T. ₁ . The second horizontal line can be the compensation noise threshold T ₂ . The processed signal after clipping as shown in FIG. 1 is as shown in FIG. 2C , and it can be clearly seen that all the points of the signal FIG. 2C are processed. None of the clipping thresholds T ₁ are exceeded, so it has an effective reduction in the maximum amplitude of the filtered signal and the PAPR is controllable. 3A is a schematic diagram of p ₁ amplitude in an embodiment, and FIG. 3B is a schematic diagram of p ₂ amplitude in an embodiment.

In the method shown in FIG. 1, the device calculates a peak clipping signal and a compensation noise of the original time domain signal, and superimposes the peak clipping signal and the compensation noise as a comprehensive peak clipping noise, and finally the integrated peak clipping. The noise is inversely superimposed on the original time domain signal to obtain an output signal such that the output signal remains at a high probability below the clipping threshold.

The method of the embodiments of the present invention is described in detail above. In order to facilitate the implementation of the above embodiments of the embodiments of the present invention, correspondingly, the apparatus of the embodiments of the present invention is provided below.

Referring to FIG. 4, FIG. 4 is a device 40 according to an embodiment of the present invention. The device 40 includes a processor 401 (the number of processors 401 may be one or more, and one processor in FIG. 4 is taken as an example). The memory 402 and the transceiver 403 (which may include a radio frequency module, an antenna, etc.), in some embodiments of the present invention, the processor 401, the memory 402, and the transceiver 403 may be connected by a bus or other means, in FIG. Connection is an example.

The memory 402 is configured to store a program;

The processor 401 calls a program in the memory 402 for performing the following operations:

Receiving an original time domain signal through the transceiver 403;

By performing the above operation, the device 40 calculates a peak clipping signal and a compensation noise of the original time domain signal, and superimposes the peak clipping signal and the compensation noise as a comprehensive peak clipping noise, and finally reverses the integrated peak clipping noise. The original time domain signal is superimposed to obtain an output signal such that the output signal remains at a high probability below the clipping threshold.

In an optional solution, the original time domain signal is composed of signals on N time-domain sampling points obtained by inverse discrete Fourier transform IDFT of N subcarriers in the frequency domain, the N time domains. The rule of calculating the peak clipping signal of the signal at the nth time domain sampling point in the sampling point is: when the amplitude of the signal on the nth time domain sampling point is less than or equal to the clipping threshold, The peak clipping signal of the signal at the nth time domain sampling point is equal to zero; when the amplitude of the signal at the nth time domain sampling point is greater than the clipping threshold, the clipping peak is calculated as :p ₁ (n)=x(n)*(1- T1/|x(n)|), where p ₁ (n) represents the peak clipping signal of the signal at the nth time domain sampling point, T1 is The clipping threshold, x(n) represents a signal on the nth time domain sampling point, and the set of N clipping signals obtained by sequentially n from 1 to N is the original time domain signal. Peak clipping signal.

In still another optional solution, when the amplitude of the signal at the nth time domain sampling point is greater than or equal to the compensation noise threshold, the compensation noise of the signal at the nth time domain sampling point Equal to zero; when the amplitude of the signal at the nth time domain sampling point is less than the compensation noise threshold, the compensation noise of the signal at the nth time domain sampling point takes one of the equivalent short vectors The value of the element, the compensation noise of the signal at any two time domain sampling points does not take the value of the same element in the equivalent short vector; the equivalent short vector is calculated as:

among them,

Transposed for conjugate of W ₁₂ .

In still another alternative, W is a discrete Fourier transform matrix that transforms the original time domain signal belonging to the discrete time signal from the time domain to the frequency domain, and W ₁ is a matrix composed of partial lines in W. The matrix formed by the partial rows corresponds to the virtual subcarriers in W.

In still another optional aspect, the first time is greater than the second time.

It should be noted that the specific implementation of the device 40 in FIG. 4 may also correspond to the corresponding description of the method embodiment shown in FIG. 1 .

In the device 40 shown in FIG. 4, the device 40 calculates a peak clipping signal and a compensation noise of the original time domain signal, and superimposes the peak clipping signal and the compensation noise as a comprehensive peaking noise, and finally integrates the signal. The peaking noise is inversely superimposed on the original time domain signal to obtain an output signal such that the output signal remains at a high probability below the clipping threshold.

Referring to FIG. 5, FIG. 5 is still another device 50 according to an embodiment of the present invention. The device 50 includes a receiving unit 501, a clipping unit 502, a compensation unit 503, a computing unit 504, and a superimposing unit 505. The detailed description of the unit is as follows:

The receiving unit 501 is configured to receive an original time domain signal;

The clipping unit 502 is configured to perform clipping processing on the original time domain signal according to a preset clipping threshold to obtain a peak clipping signal;

The compensation unit 503 performs compensation processing on the peak clipping signal according to a preset compensation noise threshold to obtain a compensation noise, wherein the compensation noise threshold is smaller than the clipping threshold;

The calculating unit 504 positively superimposes the peak clipping signal delayed by the second time and the compensation noise to obtain integrated peaking noise, wherein the product of the virtual subcarrier transformation matrix corresponding to the original time domain signal and the integrated peak clipping noise is zero;

The superimposing unit 505 inversely superimposes the integrated peaking noise to the original time domain signal delayed by the first time to obtain an output signal.

By performing the above steps, the device 40 calculates the peak clipping signal and the compensation noise of the original time domain signal, and superimposes the peak clipping signal and the compensation noise as a comprehensive peaking noise, and finally reverses the integrated peaking noise. The original time domain signal is superimposed to obtain an output signal such that the output signal remains at a high probability below the clipping threshold.

In an optional solution, the original time domain signal is composed of signals on N time-domain sampling points obtained by inverse discrete Fourier transform IDFT of N subcarriers in the frequency domain, the N time domains. The rule of calculating the peak clipping signal of the signal at the nth time domain sampling point in the sampling point is: when the amplitude of the signal on the nth time domain sampling point is less than or equal to the clipping threshold, The peak clipping signal of the signal at the nth time domain sampling point is equal to zero; when the amplitude of the signal at the nth time domain sampling point is greater than the clipping threshold, the clipping peak is calculated as :p ₁ (n)=x(n)*(1-T1/|x(n)|), where p ₁ (n) represents the peak clipping signal of the signal at the nth time domain sampling point, T1 is The clipping threshold, x(n) represents a signal on the nth time domain sampling point, and the set of N clipping signals obtained by sequentially n from 1 to N is the original time domain signal. Peak clipping signal.

among them,

Transposed for conjugate of W ₁₂ .

It should be noted that the specific implementation of each unit in the device 50 in FIG. 5 may also correspond to the corresponding description of the method embodiment shown in FIG. 1 .

In the device 50 shown in FIG. 5, the device 40 calculates a peak clipping signal and a compensation noise of the original time domain signal, and superimposes the peak clipping signal and the compensation noise as a comprehensive peaking noise, and finally integrates the signal. The peaking noise is inversely superimposed on the original time domain signal to obtain an output signal such that the output signal remains at a high probability below the clipping threshold.

In summary, by performing the embodiment of the present invention, the device calculates a peak clipping signal and a compensation noise of the original time domain signal, and superimposes the peak clipping signal and the compensation noise as a comprehensive peak clipping noise, and finally The integrated peaking noise is inversely superimposed on the original time domain signal to obtain an output signal such that the output signal remains at a high probability below the clipping threshold.

One of ordinary skill in the art can understand that all or part of the process of implementing the foregoing embodiments can be completed by a computer program to instruct related hardware, and the program can be stored in a computer readable storage medium. When executed, the flow of an embodiment of the methods as described above may be included. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

The above disclosure is only a preferred embodiment of the present invention, and of course, the scope of the present invention is not limited thereto, and those skilled in the art can understand all or part of the process of implementing the above embodiments, and according to the present invention. The equivalent changes required are still within the scope of the invention.

Claims

A clipping method for orthogonal frequency division multiplexing, which comprises:

Receiving the original time domain signal;

And cutting the original time domain signal according to a preset clipping threshold to obtain a peak clipping signal;

Performing compensation processing on the peak clipping signal according to a preset compensation noise threshold, wherein the compensation noise threshold is less than the clipping threshold;

The peak clipping signal delayed by the second time is forwardly superimposed with the compensation noise to obtain integrated peaking noise, wherein the product of the virtual subcarrier transformation matrix corresponding to the original time domain signal and the integrated peaking noise is zero;

The integrated peaking noise is inversely superimposed to the original time domain signal delayed by the first time to obtain an output signal.
The method according to claim 1, wherein the original time domain signal is composed of signals on N time-domain sampling points obtained by inverse discrete Fourier transform IDFT of N subcarriers in the frequency domain, The rule for calculating the peak clipping signal of the signal at the nth time domain sampling point among the N time domain sampling points is: when the amplitude of the signal at the nth time domain sampling point is less than or equal to the clipping a threshold clipping signal of the signal at the nth time domain sampling point is equal to zero; when the amplitude of the signal at the nth time domain sampling point is greater than the clipping threshold, the peak clipping signal The calculation formula is: p 1 (n)=x(n)*(1-T1/|x(n)|), where p 1 (n) represents the peak clipping of the signal at the nth time domain sampling point a signal, T1 is the clipping threshold, x(n) is a signal representing the nth time domain sampling point, and the set of N clipping signals obtained by sequentially n from 1 to N is A clipping signal of the original time domain signal.
The method according to claim 2, wherein when the amplitude of the signal at the nth time domain sampling point is greater than or equal to the compensation noise threshold, the signal at the nth time domain sampling point The compensation noise is equal to zero; when the amplitude of the signal at the nth time domain sampling point is smaller than the compensation noise threshold, the compensation noise of the signal at the nth time domain sampling point is taken as an equivalent short vector The value of one element, the compensation noise of the signal at any two time domain sampling points does not take the value of the same element in the equivalent short vector; the equivalent short vector is calculated as:

among them,
To represent the equivalent short vector, p 1 is a peak clipping signal representing the original time domain signal, W 1 is a virtual subcarrier transformation matrix corresponding to the original time domain signal, and W 12 is a partial column in W 1 Elements,
Transposed for conjugate of W 12 .
The method according to claim 3, wherein W is a discrete Fourier transform matrix that transforms the original time domain signal belonging to the discrete time signal from the time domain to the frequency domain, and W 1 is composed of a partial line of W A matrix, the matrix of the partial rows corresponding to the virtual subcarriers in W.
The method according to any one of claims 1 to 4, wherein the first time is greater than the second time.
An apparatus, comprising:

a receiving unit, configured to receive an original time domain signal;

a clipping unit, configured to perform clipping processing on the original time domain signal according to a preset clipping threshold to obtain a peak clipping signal;

a compensation unit, configured to perform compensation processing on the peak clipping signal according to a preset compensation noise threshold, where the compensation noise threshold is less than the clipping threshold;

a calculating unit, configured to positively superimpose the peak clipping signal delayed by the second time and the compensation noise to obtain a comprehensive peak clipping noise, wherein a product of the virtual subcarrier transformation matrix corresponding to the original time domain signal and the integrated peak clipping noise is zero;

And a superimposing unit, configured to inversely superimpose the integrated peaking noise to the original time domain signal delayed by the first time to obtain an output signal.
The apparatus according to claim 6, wherein the original time domain signal is composed of signals on N time-domain sampling points obtained by inverse discrete Fourier transform IDFT of N subcarriers in the frequency domain, The rule for calculating the peak clipping signal of the signal at the nth time domain sampling point among the N time domain sampling points is: when the amplitude of the signal at the nth time domain sampling point is less than or equal to the clipping a threshold clipping signal of the signal at the nth time domain sampling point is equal to zero; when the amplitude of the signal at the nth time domain sampling point is greater than the clipping threshold, the peak clipping signal The calculation formula is: p 1 (n)=x(n)*(1-T1/|x(n)|), where p 1 (n) represents the peak clipping of the signal at the nth time domain sampling point a signal, T1 is the clipping threshold, x(n) is a signal representing the nth time domain sampling point, and the set of N clipping signals obtained by sequentially n from 1 to N is A clipping signal of the original time domain signal.
The apparatus according to claim 7, wherein when the amplitude of the signal at the nth time domain sampling point is greater than or equal to the compensation noise threshold, the signal at the nth time domain sampling point The compensation noise is equal to zero; when the amplitude of the signal at the nth time domain sampling point is smaller than the compensation noise threshold, the compensation noise of the signal at the nth time domain sampling point is taken as an equivalent short vector The value of one element, the compensation noise of the signal at any two time domain sampling points does not take the value of the same element in the equivalent short vector; the equivalent short vector is calculated as:

among them,
To represent the equivalent short vector, p 1 is a peak clipping signal representing the original time domain signal, W 1 is a virtual subcarrier transformation matrix corresponding to the original time domain signal, and W 12 is a partial column in W 1 Elements,
Transposed for conjugate of W 12 .
The apparatus according to claim 8, wherein W is a discrete Fourier transform matrix for transforming said original time domain signal belonging to a discrete time signal from a time domain to a frequency domain, and W 1 is composed of a partial line of W A matrix, the matrix of the partial rows corresponding to the virtual subcarriers in W.
The apparatus according to any one of claims 6 to 9, wherein the first time is greater than the second time.