CN111107031B

CN111107031B - Method and device for reducing signal peak-to-average ratio

Info

Publication number: CN111107031B
Application number: CN201811252799.8A
Authority: CN
Inventors: 李扬; 杨利; 鲍东山
Original assignee: Beijing Nufront Mobile Multimedia Technology Co Ltd
Current assignee: Beijing Nufront Mobile Multimedia Technology Co Ltd
Priority date: 2018-10-25
Filing date: 2018-10-25
Publication date: 2022-09-20
Anticipated expiration: 2038-10-25
Also published as: CN111107031A

Abstract

The invention provides a method and a device for reducing signal peak-to-average power ratio, firstly preprocessing an input signal, comprising the following steps: adding different time delays and/or initial phases to all carriers of the input signal to reduce the initial peak-to-average ratio of the input signal; improving the frequency spectrum characteristic of the input signal by designing a filter; and performing peak clipping processing on the preprocessed signals. The signal peak-to-average power ratio can be reduced to a greater extent on the premise of ensuring the error vector magnitude and the adjacent channel power leakage ratio.

Description

Method and device for reducing signal peak-to-average ratio

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a method and a device for reducing a signal peak-to-average ratio.

Background

In a wireless communication system, in order to expand communication capacity and improve spectrum utilization, an orthogonal modulation scheme such as orthogonal Frequency Division multiplexing (ofdm) (orthogonal Frequency Division multiplexing) is often used. The OFDM modulation mode causes the peak-to-average ratio of signals to be larger, so that the power amplifier can work in a nonlinear area more easily, and the output power and the efficiency of the power amplifier are reduced. The conventional power backoff can solve the above problems to a certain extent, but a higher power backoff causes severe reduction in the output power and efficiency of the power amplifier, thereby resulting in a significantly reduced coverage area of the base station and poor user experience.

For this reason, many techniques for reducing the Peak-to-Average-Power-Ratio (PAPR) of the signal have been proposed, such as hard Peak clipping, hard Peak clipping + window function, frequency domain Peak clipping, and pulse cancellation. The hard peak clipping and window function can effectively solve the problem of spectrum diffusion, but can cause the PAPR to rise seriously; the resource needed by fft and ifft operation in frequency domain peak clipping is large; the offset pulse method can well take account of both the PAPR and the adjacent Channel Power leakage ratio acpr (adjacent Channel Power ratio), but the PAPR reduction capability is limited by the error Vector magnitude evm (error Vector magnitude).

In a super-high-speed broadband wireless communication system, the PAPR of an input signal is high, and according to a traditional PAPR reduction scheme, when the EVM meets the protocol requirements, the PAPR reduction amount is low and far from the system expectation. Further reduction in PAPR can be achieved by sacrificing ACPR in exchange for the strategy of EVM. However, the spectrum spread and the suppression degree are reduced, and the stray is larger after the nonlinear response of the subsequent components is amplified. At this time, in such application scenarios, a policy for reducing the PAPR to a greater extent is needed on the premise of ensuring the EVM and ACPR.

Disclosure of Invention

In view of this, the present invention provides a method and an apparatus for reducing a peak-to-average ratio of a signal, which can reduce the peak-to-average ratio of the signal to a greater extent on the premise of ensuring an error vector magnitude EVM and an adjacent channel power leakage ratio ACPR. The method is particularly suitable for scenes with high signal peak average ratio in an ultra-high-speed broadband wireless communication system, and can further improve the output power and efficiency of the power amplifier, enlarge the coverage area of equipment and improve the user experience.

An apparatus for reducing a signal peak-to-average ratio, comprising:

the preprocessing module is used for preprocessing the input signal data _ in and comprises: reducing the initial peak-to-average ratio of the input signal data _ in and/or improving the spectral characteristics of the input signal data _ in;

the preprocessing module comprises:

the adjusting unit is used for adding different time delay values and/or initial phases among all carriers of the input signal so as to reduce the initial peak-to-average ratio of the signal; and/or the presence of a gas in the gas,

and the processing unit is used for improving the spectral characteristic of the input signal data _ in, filtering the signal through the filter to improve the out-of-band rejection degree of the input data _ in and improve the in-band flatness of the input data _ in.

And the peak clipping module is used for carrying out peak clipping on the preprocessed signal data _ pp.

Further, the peak clipping module includes:

the rate conversion unit is used for converting the sampling rate of the preprocessed signal data _ pp to a specified rate according to the system clock rate requirement;

the coordinate conversion unit is used for converting the complex signal into a form of amplitude plus phase so as to realize the conversion from a rectangular coordinate to a polar coordinate;

the peak value searching unit is used for detecting peak values exceeding a given peak clipping threshold and reserving the maximum peak value according to a preset rule;

the rate regression unit is used for converting the signal rate to the original sampling rate, and the conversion process follows the principle of reserving a large value; the rate regression unit is further configured to improve the phase accuracy of the retained peak value by using a phase optimization strategy, specifically: and inserting a part of data sequence with known length into the signal, and adjusting the distribution position of the length sequence in the signal to enable the position corresponding to the reserved large peak value to be closer to the original input signal.

The energy extraction unit is used for extracting clipping energy of signals needing to be clipped according to the reserved maximum peak value and the clipping threshold;

the energy extraction unit is further configured to generate a weighting factor for weighting the clipping energy, and includes:

setting a threshold value, determining according to the peak value interval and the relative size of the peak value, and obtaining according to a traversal algorithm;

judging whether the distance between two adjacent peak values is smaller than a preset distance threshold value or not;

if the distance between two adjacent peak values is not less than a preset distance threshold value, directly carrying out peak clipping energy forming treatment; if the distance between two adjacent peak values is smaller than a preset distance threshold value, generating a clipping energy weighting factor, wherein the clipping energy weighting factor is the ratio of the distance between the peak values to the preset distance threshold value, and multiplying the clipping energy weighting factor by the clipping energy corresponding to the latter peak value in the two adjacent peak values to obtain the weighted clipping energy.

The anti-coordinate transformation unit is used for converting the amplitude + phase signals into complex signals to realize the conversion from polar coordinates to rectangular coordinates;

and the energy shaping unit is used for carrying out shaping processing through a filter according to the clipping energy and the weighting factor extracted by the energy extraction unit to generate a clipping sequence.

And the peak clipping processing unit is used for subtracting the clipping sequence from the input signal to obtain a signal after peak clipping.

The application provides a method for reducing a peak-to-average ratio of a signal, comprising:

pre-processing an input signal, comprising: reduce the initial peak-to-average ratio of the signal, and/or

Improving the spectral characteristics of the input signal;

specifically, different time delay values and/or initial phases are added among the carriers of the input signal data _ in to reduce the initial peak-to-average ratio of the signal; and the time delay values among the carriers of the input signal are distributed by evenly dividing the maximum allowed time delay value or according to an arithmetic progression.

Furthermore, the filter is designed to improve the frequency spectrum characteristic of the input signal, improve the out-of-band rejection degree of the input data _ in and improve the in-band flatness of the data _ in.

And performing peak clipping processing on the preprocessed signals, wherein the peak clipping processing comprises the following steps:

converting the sampling rate of the preprocessed input signal data _ in to a specified rate;

converting an input signal into a form of amplitude + phase to realize the conversion from a rectangular coordinate to a polar coordinate;

detecting a peak value exceeding a given peak clipping threshold, and simultaneously keeping a maximum peak value according to a certain rule;

converting the signal rate to the original sampling rate, wherein the conversion process follows the principle of reserving a large value; the phase accuracy of the reserved peak value is improved through a phase optimization strategy, and the method specifically comprises the following steps: and inserting a part of data sequence with known length into the signal, and adjusting the distribution position of the length sequence in the signal to enable the position corresponding to the reserved large peak value to be closer to the original input signal.

Extracting clipping energy of the signal according to the searched peak information and a clipping threshold;

converting the signals into complex signals to realize the conversion from polar coordinates to rectangular coordinates;

generating a weighting factor, and calculating to obtain weighted clipping energy; the calculation method of the weighting factor comprises the following steps:

Designing a shaping filter according to the weighted clipping energy, and carrying out shaping processing to generate a clipping sequence;

and subtracting the clipping sequence from the input signal to obtain a signal after peak clipping.

And a multi-stage cascade structure is adopted, and the reduction of the peak-to-average ratio of the signal is carried out on each stage so as to meet the requirements on the peak-to-average ratio of the signal in different scenes.

The application provides a method and a device for reducing the peak-to-average power ratio of a signal, firstly, an input signal is preprocessed, and the initial peak-to-average power ratio of the input signal is reduced by adding different time delays and/or initial phases among various carriers of the input signal; improving the frequency spectrum characteristic of the input signal by designing a filter; by preprocessing the signal, the frequency spectrum diffusion possibly brought by the subsequent peak clipping processing is compensated, the clipping energy is reduced, and meanwhile, the deterioration of the error vector magnitude is not caused. And then, the preprocessed signals are subjected to peak clipping processing, and the phenomena of over clipping and inaccurate peak searching can be effectively weakened through high-precision peak searching, so that the EVM and PAPR performance after clipping is improved.

For the purposes of the foregoing and related ends, the one or more embodiments include the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects and are indicative of but a few of the various ways in which the principles of the various embodiments may be employed. Other benefits and novel features will become apparent from the following detailed description when considered in conjunction with the drawings and the disclosed embodiments are intended to include all such aspects and their equivalents.

Drawings

FIG. 1 is a system diagram of an apparatus for reducing the peak-to-average power ratio of a signal according to the present invention;

FIG. 2 is a block diagram of a peak clipping module NUF _ CLIP system according to the present invention;

FIG. 3 is a schematic diagram of a multi-stage cascade configuration of the present invention;

fig. 4 is a flowchart of a method for reducing the peak-to-average ratio of a signal according to the present invention.

Detailed Description

The following description and the drawings sufficiently illustrate specific embodiments of the invention to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. The examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in or substituted for those of others. The scope of embodiments of the invention encompasses the full ambit of the claims, as well as all available equivalents of the claims. Embodiments of the invention may be referred to herein, individually or collectively, by the term "invention" merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed.

Example one

The present invention provides an apparatus for reducing peak-to-average ratio of signal, as shown in fig. 1, comprising:

100. the preprocessing module is used for preprocessing an input signal and comprises:

100a, adding different time delay values and/or initial phases among the carriers of the input signal data _ in to reduce the initial peak-to-average ratio of the signal;

specifically, different delay values and/or initial phases are added among the carriers of the input signal, so that the polarities of the phases of the carriers are staggered, and the condition of same-polarity addition during carrier combination is avoided. The carrier delay values are distributed according to the following formula by equally dividing the maximum allowable delay value or according to an arithmetic progression: delay _ number (i) ═ 0+ (i-1) × max _ Delay _ number/(N-1), where, Delay _ number (i) represents the Delay value corresponding to the ith carrier, max _ Delay _ number represents the maximum allowable Delay value, and N represents the number of carriers. For example, the maximum allowable delay value is 128 sampling points, and if there are five carriers, the delay value corresponding to each carrier is 0, 32, 64, 96, 128, respectively.

The initial phase can be obtained through a function optimal solution problem, the scheme is simple to implement, and the initial peak-to-average ratio of the input signal data _ in can be effectively reduced.

100b, a processing unit for improving the frequency spectrum characteristic of the input signal data _ in, and filtering the signal through a filter to promote the out-of-band rejection degree of the data _ in and improve the in-band flatness of the data _ in. The filter may be a filter coefficient obtained by synthesizing a plurality of filter coefficients by convolution or dot multiplication, or a plurality of filter coefficients may be used in series. The improvement of the out-of-band rejection can offset the spectrum diffusion phenomenon caused by the subsequent peak clipping treatment, thereby improving the PAPR reduction capability of the whole system; the improvement of the flatness in the band can improve the EVM value of the initial signal to a certain extent, and further improve the performance of the system.

110. A peak clipping module NUF-CLIP, configured to perform peak clipping on the preprocessed signal data _ pp to reduce the peak-to-average ratio to a specified value, as shown in fig. 2, where the peak clipping module NUF-CLIP includes:

a rate transformation unit rot (rate Of transmission) for transforming the sampling rate Of the input signal data _ in to a specified rate according to a system clock rate requirement; the resolution of the signal can be refined through rate conversion, and real peak information can be found out.

A coordinate conversion unit cc (coordinate conversion) for converting the complex signal into an "amplitude + phase" form to realize the conversion from rectangular coordinate to polar coordinate; after coordinate conversion, peak search can be performed according to the signal amplitude.

A peak search unit ps (peak search) configured to detect a peak exceeding a given peak clipping threshold, and meanwhile, retain a maximum peak therein according to a preset rule; the preset rule is three-point peak searching, four-point peak searching or sliding window peak searching.

Specifically, the peak refers to a point where the amplitude exceeds the detection threshold, and the peak is searched at three points: let the modulus values of the adjacent three peaks be A, B, C, if B ≧ A and B > C, then B is retained, and A and C are set to 0. If the inequality relationships described above are not satisfied, A, B, C are not retained and all are set to 0.

Four points are used for peak searching: setting the modulus values of the four adjacent peak values to be A, B, C, D, if B is larger than or equal to A and B is larger than C, and C is larger than or equal to B and C is satisfied simultaneously, temporarily keeping the values of B and C, setting A, D to be 0, then comparing the values of B and C, if B is larger than C, keeping the value of B, and setting C to be 0; if B < C, retaining the value of C, and simultaneously setting B to 0; if B ═ C, then the value of B is retained and C is set to 0;

searching peaks through a sliding window: a window length L is appointed, a point with the maximum module value is searched in the window length, the position of the point is assumed to be n, and if the module value A of the point is higher than a detection threshold, the point is reserved; if the detection threshold is lower, the point is not reserved. Then, the point at the position of n +1 is used as a starting point, the point with the maximum module value is searched in the range with the window length being L, and the operation is repeated.

In order to further reserve the large peak, the large peak is reserved through a detection threshold strategy, specifically: and eliminating the small peak points which are near to the threshold value and are close to the threshold, and only keeping the maximum peak point. Under certain configurations, a peak clipping threshold is a, a plurality of peak points appear near a certain position, most of the peak points are very close to the peak clipping threshold, and if the peak points are reserved, excessive clipping is caused, so that the EVM is poor. Or the system can not process simultaneously due to too many peak values, so that the real large peak value point is missed to be cut, and the phenomenon of uneven cutting is caused. The large peak value is further reserved through a detection threshold strategy, and the situation of over-clipping or uneven clipping can be effectively avoided.

A rate regression unit ROR (rate Of Return) for transforming the signal rate to the original sampling rate, wherein the transformation process follows the principle Of reserving a large value;

further, in order to improve the phase accuracy of the reserved peak value, the invention provides a phase optimization strategy, which specifically comprises the following steps: and inserting a part of data sequence with known length into the signal, and adjusting the distribution position of the length sequence in the signal to enable the position corresponding to the reserved large peak value to be closer to the original input signal, namely the phase of the large peak value is closer to the phase of the original signal. The strategy can ensure that clipping and clipping are more uniform, namely, the peak value of the time domain waveform of the signal after clipping is shown as a uniform straight line, or the PAPR value at the ten thousandth probability is closer to the peak value of the PAPR, and the EVM can be improved to a certain extent.

An Energy extraction unit cee (clipping Energy extraction) for extracting clipping Energy required to clip the signal according to the reserved larger peak value and the clipping threshold;

and a weighting factor for generating a weighting factor for weighting the clipping energy, comprising:

threshold values are set, the threshold values are determined according to the peak value distance and the relative size of the peak values, or the threshold values can be obtained according to a traversal algorithm, namely the EVM under a plurality of distance threshold values is counted, a relation curve between the EVM and the distance threshold values is drawn, and inflection points in the curve are corresponding distance threshold values.

if the distance between two adjacent peak values is not less than a preset distance threshold value, directly carrying out peak clipping energy forming treatment; and if the distance between two adjacent peak values is smaller than a preset distance threshold value, generating a clipping energy weighting factor, wherein the clipping energy weighting factor is the ratio of the distance between the peak values and the preset distance threshold value, and multiplying the clipping energy weighting factor by the clipping energy corresponding to the latter peak value in the two adjacent peak values to obtain the weighted clipping energy.

110f, an inverse Coordinate transformation unit icc (inverse Coordinate conversion) for converting the "amplitude + phase" signal into a complex signal to realize the conversion from polar coordinates to rectangular coordinates;

and the Energy shaping unit CES (clipping Energy shaping) is used for generating weighted clipping Energy according to the clipping Energy extracted by the Energy extraction unit and the weighting factor, and carrying out shaping processing through a filter to generate a clipping sequence.

A clipping processing unit cp (clipping process) for subtracting the clipping sequence from the input signal to obtain a clipped signal, where the input signal and the clipping energy are aligned in time delay.

Further, single-stage NUF-CLIP is difficult to meet PAPR requirements in all scenarios, so a cascading scheme is proposed, and a multi-stage cascading structure is adopted to perform processing of reducing the signal-to-peak-to-average ratio for each stage, as shown in fig. 3, three-stage cascading basically can meet PAPR requirements in most scenarios, and if PAPR needs to be further reduced, the PAPR can be further reduced by increasing the number of cascading.

Example two

The invention provides a method for reducing signal peak-to-average ratio, as shown in fig. 4, comprising:

s201, preprocessing an input signal data _ in, and specifically comprises the following steps: reducing the initial peak-to-average ratio of the signal and/or improving the spectral characteristics of the input signal;

specifically, the initial peak-to-average ratio of the signal is reduced by adding different delay values and/or initial phases among the carriers of the input signal, and the polarities of the phases of the carriers are staggered, so that the condition of adding the same polarity when the carriers are combined is avoided. The time delay value of each carrier is distributed by equally dividing the maximum allowed time delay value or according to an arithmetic progression, and the method is characterized by comprising the following steps of: delay _ number (i) ═ 0+ (i-1) × max _ Delay _ number/(N-1), where, Delay _ number (i) represents the Delay value corresponding to the ith carrier, max _ Delay _ number represents the maximum allowable Delay value, and N represents the number of carriers. For example, the maximum allowable delay value is 128 sampling points, and if there are five carriers, the delay value corresponding to each carrier is 0, 32, 64, 96, 128, respectively.

The frequency spectrum characteristic of the input signal data _ in is improved, the signal is filtered through a designed filter, the out-of-band rejection degree of the data _ in is improved, and the in-band flatness of the data _ in is improved. The filter may be a filter coefficient obtained by synthesizing a plurality of filter coefficients by convolution or dot multiplication, or a plurality of filter coefficients may be used in series.

The improvement of the out-of-band suppression system can offset the spectrum diffusion phenomenon caused by the subsequent peak clipping treatment, thereby improving the PAPR reduction capability of the whole system; the improvement of the flatness in the band can improve the EVM value of the initial signal to a certain extent, and further improve the performance of the system.

S202, performing peak clipping processing on the preprocessed signals.

The peak clipping processing step comprises the following steps:

(1) rate conversion, converting the sampling rate of the preprocessed input signal data _ pp to a specified rate; specifically, according to the system clock rate requirement, the sampling rate of the input signal data _ pp is converted to a specified rate, preferably the specified rate is 4 times of the bandwidth, and the conversion to the specified rate can refine the resolution of the signal and discover the real peak information.

(2) And coordinate transformation, namely converting the complex signals into a form of amplitude + phase to realize the conversion from rectangular coordinates to polar coordinates, and performing peak value search according to the amplitude of the signals after coordinate conversion.

(3) The peak value searching is used for detecting the peak value exceeding a given peak clipping threshold and simultaneously reserving the maximum peak value according to a preset rule; the preset rule is three-point peak searching, four-point peak searching or sliding window peak searching.

searching peaks through a sliding window: designating a window length L, searching a point with the maximum module value in the window length, assuming that the position of the point is n, and if the module value A of the point is higher than a detection threshold, reserving the point; if the detection threshold is lower, the point is not reserved. Then, the point at the n +1 position is used as a starting point, the point with the maximum module value is searched in the range with the window length being L, and the operation is repeated.

In order to further reserve the large peak, the large peak is reserved through a detection threshold strategy, specifically: and eliminating the small peak points which are near to the threshold value and are close to the threshold, and only keeping the maximum peak point. Under certain configurations, a peak clipping threshold is a, a plurality of peak points appear near a certain position, most of the peak points are very close to the peak clipping threshold, and if the peak points are reserved, excessive clipping is caused, so that the EVM is poor. Or the system can not process simultaneously because the number of the peak values is too much, so that the real large peak value point is missed to be cut, and the phenomenon of uneven cutting is caused. The large peak value is further reserved through a detection threshold strategy, and the condition of over-clipping or uneven clipping can be effectively avoided.

(4) Rate regression, namely converting the signal rate to the original sampling rate, wherein the conversion process follows the principle of reserving a large value;

further, in order to improve the phase accuracy of the reserved peak value, the invention provides a phase optimization strategy, which specifically comprises the following steps: and inserting a part of data sequence with known length into the signal, and adjusting the distribution position of the length sequence in the signal to enable the position corresponding to the reserved large peak value to be closer to the original input signal, namely the phase of the large peak value is closer to the phase of the original signal. The strategy can ensure more uniform clipping, namely the peak value of the time domain waveform of the signal after peak clipping is shown as a very uniform straight line, or the PAPR value at the ten thousandth probability is closer to the peak value of the PAPR, and the EVM can be improved to a certain extent.

(5) And extracting clipping energy, and extracting energy required to be reduced of the signal according to peak information and a clipping threshold searched by the peak searching unit.

Generating a weighting factor for weighting the clipping energy, comprising:

(6) The coordinate transformation is reversed, the amplitude and phase signals are converted into complex signals, and the conversion from polar coordinates to rectangular coordinates is realized

(7) And energy shaping, namely generating weighted clipping energy according to the clipping energy extracted by the energy extraction unit and the weighting factor, and carrying out shaping processing through a filter to generate a clipping sequence.

(8) And performing peak clipping processing, namely subtracting the clipping sequence from the input signal to obtain a signal after peak clipping, wherein the input signal and the clipping energy need to be aligned in time delay.

Compared with the scheme in the prior art, the invention has the following advantages:

1. compared with the traditional peak-to-average ratio reduction method, the method and the device of 'preprocessing + peak clipping processing' provided by the invention can obtain larger PAPR reduction amount on the premise of meeting the requirements of EVM and MASK protocols. The preprocessing module compensates spectrum diffusion possibly brought by subsequent peak clipping processing, reduces clipping energy of the peak clipping module NUF-CLIP, and does not influence EVM of signals;

2. by adopting the phase optimization and detection threshold strategy of the peak clipping module NUF-CLIP provided by the invention, the phenomena of over clipping and inaccurate peak value search can be effectively weakened, so that the EVM and PAPR performances after clipping are improved. The phase optimization can reduce the phase difference between the reserved peak value and the original signal at the same position, and improve the peak value searching precision, thereby improving the PAPR performance and enabling the signal cutting to be more uniform. The detection threshold can avoid the over-clipping phenomenon caused by the close arrangement of certain small peak values and large peak values, thereby improving the EVM performance.

3. By adopting a multistage cascade structure, the PAPR requirement under most scenes can be met. Meanwhile, the structure is an open type series structure, and the PAPR can be further reduced by increasing the cascade number.

Those of skill in the art will understand that the various exemplary method steps and apparatus elements described in connection with the embodiments disclosed herein can be implemented as electronic hardware, software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative steps and elements have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The steps of a method described in connection with the embodiments disclosed above may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a subscriber station. In the alternative, the processor and the storage medium may reside as discrete components in a subscriber station.

The disclosed embodiments are provided to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope or spirit of the invention. The above-described embodiments are merely preferred embodiments of the present invention, which should not be construed as limiting the invention, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. An apparatus for reducing a signal peak-to-average ratio, comprising:

the preprocessing module is used for preprocessing the input signal data _ in and comprises: reducing an initial peak-to-average ratio of the input signal data _ in, and/or improving a spectral characteristic of the input signal data _ in, includes: the adjusting unit is used for adding different time delay values and/or initial phases among all carriers of the input signal so as to reduce the initial peak-to-average ratio of the signal; and/or the processing unit is used for improving the frequency spectrum characteristic of the input signal data _ in, and filtering the signal through a filter to promote the out-of-band rejection degree of the input data _ in and improve the in-band flatness of the input data _ in;

the peak clipping module is used for performing peak clipping processing on the preprocessed signal data _ pp, and comprises the following steps: the rate conversion unit is used for converting the sampling rate of the preprocessed signal data _ pp to a specified rate according to the system clock rate requirement; the coordinate conversion unit is used for converting the complex signal into a form of amplitude + phase so as to realize the conversion from rectangular coordinates to polar coordinates; the peak value searching unit is used for detecting the peak value exceeding a given peak clipping threshold and simultaneously reserving the maximum peak value according to a preset rule; the rate regression unit is used for converting the signal rate to the original sampling rate, and the conversion process follows the principle of reserving a large value; the energy extraction unit is used for extracting the clipping energy of the signal needing to be clipped according to the reserved maximum peak value and the clipping threshold; the anti-coordinate transformation unit is used for converting the amplitude + phase signals into complex signals to realize the conversion from polar coordinates to rectangular coordinates; the energy shaping unit is used for carrying out shaping processing through a filter according to the clipping energy and the weighting factor extracted by the energy extraction unit to generate a clipping sequence; the clipping processing unit is used for subtracting the clipping sequence from the input signal to obtain a signal after clipping;

the rate regression unit is further configured to improve the phase accuracy of the retained peak value through a phase optimization strategy, specifically: and inserting a part of data sequence with known length into the signal, and adjusting the distribution position of the length sequence in the signal to enable the position corresponding to the reserved large peak value to be closer to the original input signal.

2. The apparatus for reducing peak-to-average ratio of a signal as set forth in claim 1, wherein said energy extraction unit is further configured to generate a weighting factor for weighting the clipping energy, comprising:

3. The apparatus for reducing the peak-to-average ratio of a signal according to any one of claims 1-2, wherein a multi-stage cascade structure is adopted, and the signal peak-to-average ratio reduction process is performed for each stage.

4. A method for reducing a peak-to-average ratio of a signal, comprising:

pre-processing an input signal, comprising: reducing the initial peak-to-average ratio of the signal by adding different time delay values and/or initial phases between the carriers of the input signal data _ in, and/or improving the spectral characteristics of the input signal; the time delay value among all carriers of the input signal is distributed by evenly dividing the maximum allowable time delay value or according to an arithmetic progression; the improving the spectral characteristics of the input signal comprises: improving the out-of-band rejection degree of the input data _ in; improving the in-band flatness of the data _ in;

carrying out peak clipping processing on the preprocessed signals, wherein the peak clipping processing comprises the following steps: converting the sampling rate of the preprocessed input signal data _ in to a specified rate; converting an input signal into a form of amplitude + phase to realize conversion from a rectangular coordinate to a polar coordinate; detecting a peak value exceeding a given peak clipping threshold, and simultaneously keeping a maximum peak value according to a certain rule; converting the signal rate to the original sampling rate, wherein the conversion process follows the principle of reserving a large value; extracting clipping energy of the signal according to the searched peak information and a clipping threshold; converting the signals into complex signals to realize the conversion from polar coordinates to rectangular coordinates; generating a weighting factor, and calculating to obtain weighted clipping energy; designing a shaping filter according to the weighted clipping energy, and carrying out shaping processing to generate a clipping sequence; subtracting the clipping sequence from the input signal to obtain a signal after peak clipping;

the phase accuracy of the reserved peak value is improved through a phase optimization strategy, which specifically comprises the following steps: and inserting a part of data sequence with known length into the signal, and adjusting the distribution position of the length sequence in the signal to enable the position corresponding to the reserved large peak value to be closer to the original input signal.

5. The method for reducing the peak-to-average ratio of a signal as claimed in claim 4, wherein the weighting factor is calculated by:

6. A method for reducing the peak-to-average ratio of a signal as claimed in any one of claims 4 to 5, wherein a multi-stage cascade structure is adopted, and the peak-to-average ratio of the signal is reduced for each stage.