CN112422468A - Method and system for reducing PAPR in OFDM system - Google Patents
Method and system for reducing PAPR in OFDM system Download PDFInfo
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Abstract
The invention relates to a method and a system for reducing PAPR in an orthogonal frequency division multiplexing system, which comprises the following steps: acquiring a random binary bit; carrying out Quadrature Phase Shift Keying (QPSK) modulation on the binary bits and outputting QPSK signals; performing discrete Hartley transform on the output QPSK signal, and outputting a discrete Hartley signal; performing fast Fourier transform on the output discrete Hartley signal, and outputting an orthogonal frequency division multiplexing signal; inputting the orthogonal frequency division multiplexing signal to a self-adaptive amplitude limiting module, and carrying out amplitude limiting by adopting a self-adaptive amplitude limiting algorithm; and counting the successful times of amplitude limiting in the amplitude limiting process, and outputting negative feedback to the self-adaptive amplitude limiting module based on the statistical characteristic. The method in the invention can obtain good balance between the calculation complexity and the PAPR performance.
Description
Technical Field
The present invention relates to the field of orthogonal frequency division multiplexing, and in particular, to a method and a system for reducing PAPR in an orthogonal frequency division multiplexing system.
Background
Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation technology, and has high frequency spectrum utilization rate and excellent performance of resisting intersymbol interference, so that the OFDM is widely used in various digital transmissions and communications. The OFDM system has a peak to average power ratio (PAPR), and a signal with a high PAPR has a high requirement on the performance of a system power amplifier when being transmitted, is prone to signal distortion, and directly affects the operating cost and efficiency of the entire system.
Conventional PAPR reduction methods in OFDM systems can be divided into 3 major categories: signal predistortion, coding and probability methods. Different methods often have different compromises and emphasis is placed on good PAPR performance, and good PAPR performance is often achieved by sacrificing performance such as computational complexity, bit error rate and the like.
The predistortion method is to perform predistortion processing on the OFDM signal before the OFDM signal is sent to the HPA for transmission, so as to avoid an over-high peak value and further achieve the purpose of PAPR reduction. Common predistortion methods include Clipping filtering, compression transformation, peak windowing, and peak cancellation methods. This approach has low computational complexity but introduces in-band out-of-band distortion.
The encoding method is a PAPR reduction method with self-contained error detection and correction capability by sacrificing information transmission efficiency and exchanging higher calculation complexity for certain PAPR reduction effect and better error rate performance. Common methods are linear block coding, sub-block coding, WHT transform, DHT transform, etc.
The probability method reduces the peak value superposition by changing the original signal sending probability, thereby reducing the PAPR. The probability method can be mainly divided into two types, one is to generate repeated OFDM signals to process respectively, and select the signal with the minimum peak-to-average ratio to transmit, such as selective mapping (SLM). The other is to reduce the PAPR of the signal by introducing phase changes, adding peak power suppression signals or changing frequency domain constellation points. The scheme trades good PAPR reduction effect at the cost of geometrically increased computational complexity along with the number of carriers.
In consideration of the disadvantages of the above methods, the present invention provides a PAPR reduction method based on a statistical property adaptive clipping algorithm and Discrete Hartley Transform (DHT) Transform, which can achieve a good balance between computational complexity and PAPR performance.
Disclosure of Invention
The invention aims to provide a method and a system for reducing PAPR in an orthogonal frequency division multiplexing system, which can obtain good balance between the calculation complexity and the PAPR performance.
In order to achieve the purpose, the invention provides the following scheme:
a method for PAPR reduction in an orthogonal frequency division multiplexing system, the method comprising:
acquiring a random binary bit;
carrying out Quadrature Phase Shift Keying (QPSK) modulation on the binary bits and outputting QPSK signals;
performing discrete Hartley transform on the output QPSK signal, and outputting a discrete Hartley signal;
performing fast Fourier transform on the output discrete Hartley signal, and outputting an orthogonal frequency division multiplexing signal;
inputting the orthogonal frequency division multiplexing signal to a self-adaptive amplitude limiting module, and carrying out amplitude limiting by adopting a self-adaptive amplitude limiting algorithm;
and counting the successful times of amplitude limiting in the amplitude limiting process, and outputting negative feedback to the self-adaptive amplitude limiting module based on the statistical characteristic.
Optionally, the inputting the ofdm signal to an adaptive amplitude limiting module, and the amplitude limiting using an adaptive amplitude limiting algorithm specifically includes:
s1: determining the average power mean _ power of the orthogonal frequency division multiplexing signal;
s2: determining a clipping factor CR;
s3: determining an initial clipping threshold A based on the average power of the OFDM signal and the clipping factor;
s4: determining the number count of the current points exceeding the limiting threshold and the total number of the current traversed points;
s5: judging whether all the orthogonal frequency division multiplexing subcarriers are traversed or not, if so, exiting the self-adaptive amplitude limiting module, and if not, continuing to traverse;
s6: judging whether the ratio of the count to the total is smaller than the low water level, if so, reducing the amplitude limiting threshold A in the current and subsequent traversal processes, and executing a step S8, otherwise, executing the next step;
s7: judging whether the ratio of the count to the total is greater than a high water level or not, if so, increasing the amplitude limiting threshold A in the current and subsequent traversal processes, and executing the next step;
s8: judging whether the signal power of the point is greater than an amplitude limiting threshold A, if so, executing the next step, and if not, executing the step S12;
s9: judging whether the ratio of the count to the total is smaller than a locality threshold, if so, executing the next step, and if not, executing the step S11;
s10: compressing the signal power of the point based on the locality threshold and the compression factor, and executing the next step;
s11: clipping the signal to a clipping threshold A, clipping the signal higher than the clipping threshold A, wherein the count is count + 1;
S12：total＝total+1；
s13: returning to step S5 until all symbols are output from the adaptive clipping module.
Optionally, the following formula is specifically adopted for determining the initial clipping threshold a based on the average power of the ofdm signal and the clipping factor:
a ═ CR × sqrt (mean _ power), where CR ∈ (0,1) denotes a clipping factor, and mean _ power denotes an average power of the orthogonal frequency division multiplexing signal.
Optionally, the low water level belongs to an interval [0,1], the high water level belongs to an interval [0,1], the local threshold belongs to an interval [0,1], and the local threshold is a value between the high water level and the low water level.
Optionally, based on the locality threshold and the compression factor, the following formula is specifically adopted for compressing the signal power at the point:
y (n) ═ x (n) × CF, where x (n) is the original signal, CF is the compression factor, and y (n) is the compressed signal.
The present invention additionally provides a system for PAPR reduction in an orthogonal frequency division multiplexing system, the system comprising:
the random binary bit acquisition module is used for acquiring random binary bits;
the QPSK modulation module is used for carrying out quadrature phase shift keying QPSK modulation on the binary bit and outputting a QPSK signal;
the discrete Hartley transform module is used for carrying out discrete Hartley transform on the output QPSK signal and outputting a discrete Hartley signal;
the fast Fourier transform module is used for carrying out fast Fourier transform on the output discrete Hartley signal and outputting an orthogonal frequency division multiplexing signal;
the amplitude limiting module is used for inputting the orthogonal frequency division multiplexing signal to the self-adaptive amplitude limiting module and carrying out amplitude limiting by adopting a self-adaptive amplitude limiting algorithm;
and the negative feedback module is used for counting the successful amplitude limiting times in the amplitude limiting process and outputting negative feedback to the self-adaptive amplitude limiting module based on the statistical characteristics.
Optionally, the amplitude limiting module specifically includes:
an average power determining unit for determining an average power mean _ power of the orthogonal frequency division multiplexing signal;
a clipping factor determination unit for determining a clipping factor CR;
an initial clipping threshold determination unit, configured to determine an initial clipping threshold a based on the average power of the orthogonal frequency division multiplexing signal and the clipping factor;
the device comprises an amplitude limiting threshold exceeding point number and total point number determining unit, a limiting threshold exceeding point number and total point number determining unit and a limiting threshold exceeding point number and total point number determining unit, wherein the current point number count exceeding the amplitude limiting threshold and the current traversed total point number are determined;
the first judgment unit is used for judging whether all the orthogonal frequency division multiplexing subcarriers are traversed or not, if so, the self-adaptive amplitude limiting module is quitted, the traversal is finished, and if not, the traversal is continued;
the second judgment unit is used for judging whether the ratio of the count to the total is smaller than the low water level or not, if so, reducing the amplitude limiting threshold A in the current and subsequent traversal processes, executing the fourth judgment unit, and if not, executing the next unit;
the third judging unit is used for judging whether the ratio of the count to the total is greater than the high water level or not, if so, increasing the amplitude limiting threshold A in the current and subsequent traversing processes, and executing the next unit;
a fourth judging unit, configured to judge whether the signal power at the point is greater than the amplitude limiting threshold a, if yes, execute the next unit, and if not, execute the counting unit;
the fifth judging unit is used for judging whether the ratio of the count to the total is smaller than a local threshold or not, if so, executing the next unit, and if not, executing the amplitude limiting and cutting unit;
the compression unit compresses the power of the point signal based on the locality threshold and the compression factor and executes the next unit;
the amplitude limiting and cutting unit is used for limiting the signal to an amplitude limiting threshold A and cutting the signal higher than the amplitude limiting threshold A, wherein the count is count + 1;
the counting unit is used for counting total which is total + 1;
and the circulating unit is used for returning to the first judging unit until all the symbols are output from the self-adaptive amplitude limiting module.
Optionally, the initial clipping threshold determining unit specifically uses the following formula:
a ═ CR × sqrt (mean _ power), where CR ∈ (0,1) denotes a clipping factor, and mean _ power denotes an average power of the orthogonal frequency division multiplexing signal.
Optionally, the low water level belongs to an interval [0,1], the high water level belongs to an interval [0,1], the local threshold belongs to an interval [0,1], and the local threshold is a value between the high water level and the low water level.
Optionally, the compression unit specifically adopts the following formula:
y (n) ═ x (n) × CF, where x (n) is the original signal, CF is the compression factor, and y (n) is the compressed signal.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides a PAPR reduction scheme based on a statistical characteristic self-adaptive amplitude limiting algorithm and Discrete Hartley Transform (DHT) conversion, which is implemented by acquiring random binary bits; carrying out Quadrature Phase Shift Keying (QPSK) modulation on the binary bits and outputting QPSK signals; performing discrete Hartley transform on the output QPSK signal, and outputting a discrete Hartley signal; performing fast Fourier transform on the output discrete Hartley signal, and outputting an orthogonal frequency division multiplexing signal; inputting the orthogonal frequency division multiplexing signal to a self-adaptive amplitude limiting module, and carrying out amplitude limiting by adopting a self-adaptive amplitude limiting algorithm; the successful times of amplitude limiting are counted in the amplitude limiting process, and output and negatively fed back to the self-adaptive amplitude limiting module based on the statistical characteristics.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is a flowchart of a PAPR reduction method in an ofdm system according to an embodiment of the present invention;
FIG. 2 is a flow chart of an adaptive clipping algorithm according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a system for reducing PAPR in an ofdm system 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 below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a method and a system for reducing PAPR in an orthogonal frequency division multiplexing system, which can obtain good balance between the calculation complexity and the PAPR performance.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The invention takes QPSK-OFDM system as an example, because the traditional clipping scheme adopts a fixed threshold, too low threshold will introduce too much out-of-band noise, and too high threshold will result in poor PAPR performance.
In order to improve the above disadvantages, the threshold iteration of the conventional clipping scheme is improved, and an adaptive clipping algorithm based on statistical characteristics and a PAPR reduction scheme (ACA-DHT) of Discrete Hartley Transform (DHT) are proposed. The scheme comprises the following steps: generating a QPSK signal according to the input binary bits; performing Inverse Discrete Hartley Transform (IDHT) on the QPSK signal to obtain an IDHT signal; performing Inverse Fast Fourier Transform (IFFT) on the IDHT signal to obtain an OFDM signal; generating an initial amplitude limiting threshold according to the average power of the OFDM signal and the amplitude limiting factor; and inputting the OFDM signal into a self-adaptive amplitude limiting module, and performing negative feedback amplitude limiting optimization according to the statistical characteristic in the carrier traversal process so as to finish self-adaptive amplitude limiting.
Fig. 1 is a flowchart of a method for reducing PAPR in an orthogonal frequency division multiplexing system according to an embodiment of the present invention, where as shown in fig. 1, the method includes:
step 101: a random binary bit is obtained.
Step 102: and carrying out Quadrature Phase Shift Keying (QPSK) modulation on the binary bits and outputting QPSK signals.
Step 103: and carrying out discrete Hartley transformation on the output QPSK signal and outputting a discrete Hartley signal.
The discrete Hartley transform and the discrete Hartley inverse transform have symmetry, so that the modulation and demodulation of a digital signal processing chip are easy, the real value of an output signal can be ensured without an Hermite symmetric algorithm, and the system space can be effectively saved.
Step 104: and carrying out fast Fourier transform on the output discrete Hartley signal and outputting an orthogonal frequency division multiplexing signal.
Step 105: and inputting the orthogonal frequency division multiplexing signal to a self-adaptive amplitude limiting module, and carrying out amplitude limiting by adopting a self-adaptive amplitude limiting algorithm.
As shown in fig. 2, the method specifically includes the following steps:
s1: the average power mean power of the orthogonal frequency division multiplexing signal is determined.
S2: the clipping factor cr (clippingratio) is determined, and the value range is generally (0, 1).
S3: an initial clipping threshold a is determined based on the average power of the orthogonal frequency division multiplexing signal and the clipping factor.
Specifically, a ═ CR × sqrt (mean _ power), where CR ∈ (0,1) denotes a clipping factor, and mean _ power denotes an average power of the orthogonal frequency division multiplexing signal.
S4: and determining the number count of the current points exceeding the limiting threshold and the total number of the current traversed points.
Its initial value is 0.
S5: and judging whether all the orthogonal frequency division multiplexing subcarriers are traversed or not, if so, exiting the self-adaptive amplitude limiting module, and if not, continuing the traversal.
S6: and judging whether the ratio of the count to the total is smaller than the low water level, if so, reducing the amplitude limiting threshold A in the current and subsequent traversal processes, executing the step S8, and if not, executing the next step.
Wherein the low water level belongs to the interval [0,1 ].
S7: and judging whether the ratio of the count to the total is greater than the high water level, if so, increasing the amplitude limiting threshold A in the current and subsequent traversal processes, and executing the next step.
Wherein the high water level belongs to the interval [0,1 ].
S8: and judging whether the signal power of the point is greater than the amplitude limiting threshold A, if so, executing the next step, and if not, executing the step S12.
Where the locality threshold belongs to the interval [0,1], the locality threshold is usually set to a value between the high and low water levels, in order to avoid the following situations not complying with the negative feedback mechanism: if the locality threshold is set to a value lower than the low level, the signal may be compressed again at S10, possibly after the judgment at S6 is yes and the clipping threshold is decreased; if the local threshold is set to a value higher than high, then the signal that would have been clipped is made to be over-clipped (whether over-clipped or not is defined by the ratio of count to total and the low level) and it is now also desired to re-compress the clipped signal.
S9: and judging whether the ratio of the count to the total is smaller than a locality threshold, if so, executing the next step, and if not, executing the step S11.
S10: based on the locality threshold and the compression factor, the signal power at this point is compressed (without changing the clipping threshold a), and the next step is performed.
The compression specifically uses the following formula:
y (n) ═ x (n) × CF, where x (n) is the original signal, CF is the compression factor, and y (n) is the compressed signal.
S11: and clipping the signal to a clipping threshold A, and clipping the signal which is higher than the clipping threshold A, wherein the count is equal to the count + 1.
S12：total＝total+1。
S13: returning to step S5 until all symbols are output from the adaptive clipping module.
Step 106: and counting the successful times of amplitude limiting in the amplitude limiting process, and outputting negative feedback to the self-adaptive amplitude limiting module based on the statistical characteristic.
Fig. 3 is a schematic structural diagram of a system for reducing PAPR in an orthogonal frequency division multiplexing system according to an embodiment of the present invention, and as shown in fig. 3, the system includes:
a random binary bit obtaining module 201, configured to obtain a random binary bit;
a QPSK modulation module 202, configured to perform quadrature phase shift keying QPSK modulation on the binary bit and output a QPSK signal;
a discrete hartley transform module 203, configured to perform a discrete hartley transform on the output QPSK signal, and output a discrete hartley signal;
a fast fourier transform module 204, configured to perform fast fourier transform on the output discrete hartley signal, and output an orthogonal frequency division multiplexing signal;
the amplitude limiting module 205 is configured to input the orthogonal frequency division multiplexing signal to the adaptive amplitude limiting module, and perform amplitude limiting by using an adaptive amplitude limiting algorithm;
and the negative feedback module 206 is used for counting the number of times of successful amplitude limiting in the amplitude limiting process and outputting negative feedback to the self-adaptive amplitude limiting module based on the statistical characteristics.
The clipping module 205 specifically includes:
an average power determining unit for determining an average power mean _ power of the orthogonal frequency division multiplexing signal;
a clipping factor determination unit for determining a clipping factor CR;
an initial clipping threshold determination unit, configured to determine an initial clipping threshold a based on the average power of the orthogonal frequency division multiplexing signal and the clipping factor;
the device comprises an amplitude limiting threshold exceeding point number and total point number determining unit, a limiting threshold exceeding point number and total point number determining unit and a limiting threshold exceeding point number and total point number determining unit, wherein the current point number count exceeding the amplitude limiting threshold and the current traversed total point number are determined;
the first judgment unit is used for judging whether all the orthogonal frequency division multiplexing subcarriers are traversed or not, if so, the self-adaptive amplitude limiting module is quitted, the traversal is finished, and if not, the traversal is continued;
the second judgment unit is used for judging whether the ratio of the count to the total is smaller than the low water level or not, if so, reducing the amplitude limiting threshold A in the current and subsequent traversal processes, executing the fourth judgment unit, and if not, executing the next unit;
the third judging unit is used for judging whether the ratio of the count to the total is greater than the high water level or not, if so, increasing the amplitude limiting threshold A in the current and subsequent traversing processes, and executing the next unit;
a fourth judging unit, configured to judge whether the signal power at the point is greater than the amplitude limiting threshold a, if yes, execute the next unit, and if not, execute the counting unit;
the fifth judging unit is used for judging whether the ratio of the count to the total is smaller than a local threshold or not, if so, executing the next unit, and if not, executing the amplitude limiting and cutting unit;
the compression unit compresses the power of the point signal based on the locality threshold and the compression factor and executes the next unit;
the amplitude limiting and cutting unit is used for limiting the signal to an amplitude limiting threshold A and cutting the signal higher than the amplitude limiting threshold A, wherein the count is count + 1;
the counting unit is used for counting total which is total + 1;
and the circulating unit is used for returning to the first judging unit until all the symbols are output from the self-adaptive amplitude limiting module.
The initial clipping threshold determining unit specifically adopts the following formula:
a ═ CR × sqrt (mean _ power), where CR ∈ (0,1) denotes a clipping factor, and mean _ power denotes an average power of the orthogonal frequency division multiplexing signal.
The compression unit specifically adopts the following formula:
y (n) ═ x (n) × CF, where x (n) is the original signal, CF is the compression factor, and y (n) is the compressed signal.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (10)
1. A method for PAPR reduction in an orthogonal frequency division multiplexing system, the method comprising:
acquiring a random binary bit;
carrying out Quadrature Phase Shift Keying (QPSK) modulation on the binary bits and outputting QPSK signals;
performing discrete Hartley transform on the output QPSK signal, and outputting a discrete Hartley signal;
performing fast Fourier transform on the output discrete Hartley signal, and outputting an orthogonal frequency division multiplexing signal;
inputting the orthogonal frequency division multiplexing signal to a self-adaptive amplitude limiting module, and carrying out amplitude limiting by adopting a self-adaptive amplitude limiting algorithm;
and counting the successful times of amplitude limiting in the amplitude limiting process, and outputting negative feedback to the self-adaptive amplitude limiting module based on the statistical characteristic.
2. The method according to claim 1, wherein the ofdm signal is input to an adaptive clipping module, and clipping by using an adaptive clipping algorithm specifically includes:
s1: determining the average power mean _ power of the orthogonal frequency division multiplexing signal;
s2: determining a clipping factor CR;
s3: determining an initial clipping threshold A based on the average power of the OFDM signal and the clipping factor;
s4: determining the number count of the current points exceeding the limiting threshold and the total number of the current traversed points;
s5: judging whether all the orthogonal frequency division multiplexing subcarriers are traversed or not, if so, exiting the self-adaptive amplitude limiting module, and if not, continuing to traverse;
s6: judging whether the ratio of the count to the total is smaller than the low water level, if so, reducing the amplitude limiting threshold A in the current and subsequent traversal processes, and executing a step S8, otherwise, executing the next step;
s7: judging whether the ratio of the count to the total is greater than a high water level or not, if so, increasing the amplitude limiting threshold A in the current and subsequent traversal processes, and executing the next step;
s8: judging whether the signal power of the point is greater than an amplitude limiting threshold A, if so, executing the next step, and if not, executing the step S12;
s9: judging whether the ratio of the count to the total is smaller than a locality threshold, if so, executing the next step, and if not, executing the step S11;
s10: compressing the signal power of the point based on the locality threshold and the compression factor, and executing the next step;
s11: clipping the signal to a clipping threshold A, clipping the signal higher than the clipping threshold A, wherein the count is count + 1;
S12：total＝total+1；
s13: returning to step S5 until all symbols are output from the adaptive clipping module.
3. The method according to claim 2, wherein the determining the initial clipping threshold a based on the average power of the ofdm signal and the clipping factor specifically uses the following formula:
a ═ CR × sqrt (mean _ power), where CR ∈ (0,1) denotes a clipping factor, and mean _ power denotes an average power of the orthogonal frequency division multiplexing signal.
4. The method according to claim 2, wherein the low level belongs to an interval [0,1], the high level belongs to an interval [0,1], the local threshold belongs to an interval [0,1], and the local threshold is a value between the high level and the low level.
5. The method according to claim 1, wherein based on the locality threshold and the compression factor, the following formula is specifically adopted for compressing the signal power at the point:
y (n) ═ x (n) × CF, where x (n) is the original signal, CF is the compression factor, and y (n) is the compressed signal.
6. A system for PAPR reduction in an orthogonal frequency division multiplexing system, the system comprising:
the random binary bit acquisition module is used for acquiring random binary bits;
the QPSK modulation module is used for carrying out quadrature phase shift keying QPSK modulation on the binary bit and outputting a QPSK signal;
the discrete Hartley transform module is used for carrying out discrete Hartley transform on the output QPSK signal and outputting a discrete Hartley signal;
the fast Fourier transform module is used for carrying out fast Fourier transform on the output discrete Hartley signal and outputting an orthogonal frequency division multiplexing signal;
the amplitude limiting module is used for inputting the orthogonal frequency division multiplexing signal to the self-adaptive amplitude limiting module and carrying out amplitude limiting by adopting a self-adaptive amplitude limiting algorithm;
and the negative feedback module is used for counting the successful amplitude limiting times in the amplitude limiting process and outputting negative feedback to the self-adaptive amplitude limiting module based on the statistical characteristics.
7. The system for PAPR reduction in an orthogonal frequency division multiplexing system according to claim 6, wherein the clipping module specifically includes:
an average power determining unit for determining an average power mean _ power of the orthogonal frequency division multiplexing signal;
a clipping factor determination unit for determining a clipping factor CR;
an initial clipping threshold determination unit, configured to determine an initial clipping threshold a based on the average power of the orthogonal frequency division multiplexing signal and the clipping factor;
the device comprises an amplitude limiting threshold exceeding point number and total point number determining unit, a limiting threshold exceeding point number and total point number determining unit and a limiting threshold exceeding point number and total point number determining unit, wherein the current point number count exceeding the amplitude limiting threshold and the current traversed total point number are determined;
the first judgment unit is used for judging whether all the orthogonal frequency division multiplexing subcarriers are traversed or not, if so, the self-adaptive amplitude limiting module is quitted, the traversal is finished, and if not, the traversal is continued;
the second judgment unit is used for judging whether the ratio of the count to the total is smaller than the low water level or not, if so, reducing the amplitude limiting threshold A in the current and subsequent traversal processes, executing the fourth judgment unit, and if not, executing the next unit;
the third judging unit is used for judging whether the ratio of the count to the total is greater than the high water level or not, if so, increasing the amplitude limiting threshold A in the current and subsequent traversing processes, and executing the next unit;
a fourth judging unit, configured to judge whether the signal power at the point is greater than the amplitude limiting threshold a, if yes, execute the next unit, and if not, execute the counting unit;
the fifth judging unit is used for judging whether the ratio of the count to the total is smaller than a local threshold or not, if so, executing the next unit, and if not, executing the amplitude limiting and cutting unit;
the compression unit compresses the power of the point signal based on the locality threshold and the compression factor and executes the next unit;
the amplitude limiting and cutting unit is used for limiting the signal to an amplitude limiting threshold A and cutting the signal higher than the amplitude limiting threshold A, wherein the count is count + 1;
the counting unit is used for counting total which is total + 1;
and the circulating unit is used for returning to the first judging unit until all the symbols are output from the self-adaptive amplitude limiting module.
8. The system according to claim 7, wherein the initial clipping threshold determining unit specifically uses the following formula:
a ═ CR × sqrt (mean _ power), where CR ∈ (0,1) denotes a clipping factor, and mean _ power denotes an average power of the orthogonal frequency division multiplexing signal.
9. The system according to claim 7, wherein the low level belongs to an interval [0,1], the high level belongs to an interval [0,1], the local threshold belongs to an interval [0,1], and the local threshold is a value between the high level and the low level.
10. The system according to claim 7, wherein the compressing unit specifically adopts the following formula:
y (n) ═ x (n) × CF, where x (n) is the original signal, CF is the compression factor, and y (n) is the compressed signal.
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