CN111628953B - Method for reducing peak-to-average ratio of OFDM signal - Google Patents

Method for reducing peak-to-average ratio of OFDM signal Download PDF

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CN111628953B
CN111628953B CN202010348541.9A CN202010348541A CN111628953B CN 111628953 B CN111628953 B CN 111628953B CN 202010348541 A CN202010348541 A CN 202010348541A CN 111628953 B CN111628953 B CN 111628953B
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CN111628953A (en
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谢映海
吴斌
李先怀
李宏文
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Zhonghui Microelectronics Co ltd
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Abstract

The method for reducing the peak-to-average ratio of the OFDM signals comprises the following steps: at a signal sending end, circularly moving, scrambling, channel coding, constellation mapping, inserting pilot frequency and IFFT calculation are carried out on binary information bit stream signals, peak-to-average ratio values of OFDM symbols are obtained through respective calculation, the maximum value is selected to be compared with a set threshold value, if the maximum value of the peak-to-average ratio values is smaller than or equal to the set threshold value, a subsequent signal processing flow is entered and the signals are sent, and when the peak-to-average ratio values of the generated binary information bit stream signals are smaller than or equal to the set threshold value or the number of circulation times exceeds the upper limit, the signal sending is finished; and after receiving the signal, the signal receiving end removes the cyclic prefix, FFT operation, channel estimation demodulation, channel decoding and inverse scrambling, reversely and circularly moves the signal after inverse scrambling and carries out CRC check operation, if the check results are all 0, the signal receiving is finished, and when the CRC check results of the signal after circular movement are all 0 or the cycle times exceed the upper limit, the signal receiving is finished.

Description

Method for reducing peak-to-average ratio of OFDM signal
Technical Field
The invention belongs to the technical field of signal processing, and particularly relates to a method for reducing the peak-to-average ratio of OFDM signals based on information bit sending order optimization selection.
Background
The OFDM communication technology is a communication technology adopted by a mainstream broadband digital communication system at present, and modulates a bit stream onto orthogonal subcarriers for transmission, so that fading experienced by each subchannel is relatively flat, and then introduces a cyclic prefix as an inter-symbol guard interval to maintain orthogonality between the subcarriers, thereby reducing the influence of inter-symbol interference. Compared with the conventional frequency division multiplexing system, the OFDM communication system can effectively utilize limited frequency spectrum resources to the maximum extent under the condition of ensuring the orthogonality among carriers, has the characteristics of high frequency spectrum utilization rate, good multipath effect resistance and the like, and provides a simple and low-cost implementation mode through fast Fourier transform. As shown in fig. 1, the signal transmission and reception flow of the conventional OFDM communication system is as follows: at a signal sending end, adding Cyclic Redundancy Check (CRC) bits in information bit signals, then scrambling and signal coding, then carrying out carrier constellation mapping, pilot frequency insertion, IFFT (inverse fast Fourier transform) operation and cyclic prefix addition on the coded information bit signals, and finally sending out the signals by a radio frequency front end of the signal sending end. At a signal receiving end, after a radio frequency front end of the signal receiving end receives a signal, an opposite operation process is carried out, a cyclic prefix is removed, FFT operation (fast Fourier transform) is carried out, then channel estimation, demodulation, channel decoding, inverse scrambling and CRC check are carried out, and a transmitted signal is obtained.
A significant disadvantage of the OFDM communication system is a high peak-to-average power ratio (PAPR), which causes large fluctuation of instantaneous value of the output signal. The signal peak-to-average ratio is too large, and higher requirements are also put forward on devices such as a power amplifier, an A/D (analog/digital) converter and a D/A (digital/analog) converter of sending-end equipment, and the devices are required to have a large linear dynamic range, so that not only can the hardware cost be increased, but also the efficiency of the power amplifier is greatly reduced, and a large pressure is brought to the low-power-consumption design of the equipment, and the intermodulation interference and out-of-band power radiation among subcarriers can be caused, so that the performance of the whole OFDM communication system is reduced. In addition, the nonlinearity of these devices also causes nonlinear distortion of signals with a large dynamic range, and the generated harmonics cause mutual interference among subchannels, thereby affecting the communication performance of the OFDM communication system.
In order to reduce the peak-to-average ratio of the signal, researchers have studied and analyzed from many aspects, and proposed various methods for reducing the peak-to-average ratio of the OFDM signal, which are mainly classified into three categories: predistortion techniques, coding techniques, probability techniques. The predistortion technology brings certain distortion to a transmission signal, so that the communication performance is reduced; the coding technology has high computational complexity and can reduce the frequency spectrum utilization rate of the system; the probabilistic techniques require increased transmission and processing of sideband information, increasing the complexity of the system. In addition, the main indexes for measuring the inhibition method of the peak-to-average ratio comprise the inhibition effect of the peak-to-average ratio, the transmission performance and the calculation complexity, and the above several peak-to-average ratio value inhibition technologies are difficult to obtain better balance on the three indexes, so that an improvement space still exists.
Disclosure of Invention
The invention aims to provide a method for reducing the peak-to-average ratio of OFDM signals based on information bit sending order optimal selection.
In order to achieve the purpose, the invention adopts the following technical solutions:
the method for reducing the peak-to-average ratio of the OFDM signals comprises the following steps:
s1, at a signal sending end, circularly moving a binary information bit stream signal corresponding to a packet signal to be sent by X bits, wherein the initial value of X is 0;
s2, scrambling, channel coding, constellation mapping, pilot frequency insertion and IFFT calculation are carried out on the binary information bit stream signal after the cyclic shift, and a signal containing K OFDM symbols is obtained, wherein K is the number of the OFDM symbols in one-time grouping signal transmission;
s3, respectively calculating the peak-to-average ratio values of K OFDM symbols, selecting a maximum value PAPR1 as the peak-to-average ratio value of the binary information bit stream signal after the cyclic shift, comparing the maximum value PAPR1 of the peak-to-average ratio value with a set threshold value C, if the maximum value PAPR1 of the peak-to-average ratio value is not more than the set threshold value C, considering that the peak-to-average ratio value of the signal to be transmitted meets the requirement, entering a subsequent signal processing flow and transmitting, and if the maximum value PAPR1 of the peak-to-average ratio value is more than the set threshold value C, entering a step S4;
s4, judging whether X is larger than W, if X is larger than W, selecting a binary information bit stream signal with the minimum peak-to-average ratio from the generated binary information bit stream signals after cyclic shift, and entering a subsequent signal processing flow and transmitting; otherwise, enabling X = X +1, and returning to the step S1, wherein W is an upper limit value of the information bit cycle moving times; when the peak-to-average ratio of the generated binary information bit stream signal after cyclic shift is less than or equal to a set threshold value C, or the cycle number exceeds W, the transmission process of the signal is finished;
s5, a signal receiving end receives the signal, and conventional steps such as cyclic prefix removal, FFT operation, channel estimation demodulation, channel decoding, inverse scrambling and the like are sequentially carried out to obtain an inverse scrambled signal;
s6, reversely and circularly moving the inversely scrambled signals
Figure BDA0002471053870000031
The number of bits is set to be,
Figure BDA0002471053870000032
the initial value of (a) is 0;
s7, performing CRC operation on the signals after reverse cyclic movement, and if the check results are all 0, determining that the packet signals sent by the sending end are correctly received, and ending signal receiving; if the checking result is not 0, the packet signal sent by the sending end is not received correctly, and step S8 is executed;
s8, judging
Figure BDA0002471053870000033
Whether or not it is greater than W, if
Figure BDA0002471053870000034
If the signal is larger than W, the signal receiving is considered to be wrong, the signal receiving is finished, otherwise, the signal receiving is ordered
Figure BDA0002471053870000035
Returning to the step S6; and when the CRC results of the signals after the cyclic shift are all 0 or the cycle number exceeds W, ending the receiving process of the signals.
Further, at the signal transmitting end, the binary information bit stream signal corresponding to the packet signal to be transmitted is circularly shifted left or circularly shifted right, and for the binary information bit stream signal corresponding to the same packet signal to be transmitted, the directions of circular shifting are consistent.
According to the technical scheme, the method generates an OFDM signal with a lower peak-to-average ratio value for transmission by optimally selecting the transmission sequence of uncoded information bits so as to improve the peak-to-average ratio value performance of the transmitted signal; and the receiving end fully utilizes the judgment of the cyclic redundancy check bits on whether the information receiving result is correct or not, and can search out the correct sending sequence of the uncoded information bits through the CRC blind detection with low complexity under the condition of not needing the auxiliary judgment of the sideband information. Compared with the traditional peak-to-average power ratio reduction algorithm, the method has the advantages that the transmitted signal is distortion-free and the utilization rate of the system frequency spectrum is not reduced, so that the loss of the system communication performance is not caused; meanwhile, the receiving end has blind judgment capability, so that sideband information does not need to be transmitted in an auxiliary mode, and better peak-to-average power ratio performance can be obtained in short grouped signals with less OFDM symbols under the condition that the existing signal processing flow is not changed obviously.
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In order to illustrate the embodiments of the present invention more clearly, the drawings that are needed in the description of the embodiments or the prior art 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 that other drawings can be obtained by those skilled in the art without inventive effort.
Fig. 1 is a flow chart of transmission and reception of an OFDM signal;
FIG. 2 is a signal processing flow chart of a signal transmitting end of the method of the present invention;
FIG. 3 is a flow chart of signal processing at the signal receiving end according to the method of the present invention;
fig. 4 is a graph of complementary cumulative distribution functions of the transmitted signals shifted left by different cycles.
Detailed Description
In order to make the aforementioned and other objects, features and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
The method for reducing the peak-to-average ratio of the OFDM signal is to reduce the peak-to-average ratio of the signal by optimizing the sending sequence of information bits after adding Cyclic Redundancy Check (CRC) bits in a binary information bit stream signal.
The method of the present invention is described below with reference to fig. 2 and 3, and the steps of the method of the present invention are as follows: at the signal sending end, a packet signal to be sent at a certain time of the physical layerBinary information bit stream signal S = [ S ] with length L corresponding to number 1 ,s 2 ,…,s L ],s l =0 or 1,l =1, …, L is the length of the bitstream signal, and in the binary information bitstream signal S, the last R bits are CRC check bits of the packet signal transmitted this time;
s1, circularly moving a binary information bit stream signal S by X bits, wherein the initial value of X is 0, and circularly moving can be circularly left-moving the X bits or circularly right-moving the X bits, but in the same signal processing process, when the circularly moving step is repeated, the circularly moving direction is consistent, for example, for the binary information bit stream signal of a packet signal to be transmitted, when the first circularly moving is left-moving, the secondary information bit stream signal is circularly left-moving when circularly moving is repeatedly executed at the subsequent time (2 nd, 3 rd, …, W th time); generating a new set of circularly moved binary information bit stream signals each time a circular movement is performed;
s2, scrambling, channel coding, constellation mapping, pilot frequency insertion and IFFT calculation are carried out on the binary information bit stream signal S after circular movement, and a signal containing K OFDM symbols is obtained; k is the number of OFDM symbols in one-time grouped signal transmission, the processing mechanisms of scrambling, channel coding, constellation mapping, pilot frequency insertion and IFFT calculation of a signal by a transmitting end in the method are the same as the processing mechanisms of scrambling, channel coding, constellation mapping, pilot frequency insertion and IFFT calculation in the traditional OFDM signal transmission, the steps are not innovation points of the invention, and the description is not repeated;
s3, respectively calculating the peak-to-average ratio values of K OFDM symbols, selecting a maximum value PAPR1 as the peak-to-average ratio value of the binary information bit stream signal after the cyclic shift, comparing the maximum value PAPR1 of the peak-to-average ratio value with a set threshold value C, if the maximum value PAPR1 of the peak-to-average ratio value is not more than the set threshold value C, considering that the peak-to-average ratio value of the signal to be transmitted meets the requirement, entering a subsequent signal processing flow and transmitting, and if the maximum value PAPR1 of the peak-to-average ratio value is more than the set threshold value C, entering a step S4; the signal processing flow and the transmitting flow are consistent with those of the existing method, which is not an innovation point of the invention and is not described herein;
s4, judging whether X is larger than W, if X is larger than W, selecting a signal with the minimum peak-to-average ratio value from the obtained binary information bit stream signal after cyclic shift, and entering a subsequent signal processing flow and transmitting; if X is less than or equal to W, making X = X +1, and returning to the step S1; w is the upper limit value of the information bit cyclic shift times; except that the binary information bit stream signal S is circularly shifted for the first time (X = 0), after each subsequent step S1, the binary information bit stream signal S generates a new bit stream signal due to position shift, for example, the binary information bit stream signal S is circularly shifted by 1 bit to the left when step S1 is circularly shifted for the 2 nd time, and the new signal after circular shift is S _1= [ S =0 ] 2 ,…,s L ,s 1 ]By analogy, when step S1 is executed in the 3 rd cycle, the information bit signal is circularly shifted by 2 bits to the left, and the new signal after circular shift is obtained as S _2= [ S ] 3 ,…,s L ,s 1 ,s 2 ](ii) a When the peak-to-average ratio values of the generated bitstream signals are all less than or equal to a set threshold value C, or the number of cycles exceeds W, the transmission process of the signals is ended, where W =15 in this embodiment; the value of W can be set according to requirements, when the value of W is larger, the effect of reducing the peak-to-average ratio value is better, but the calculated amount is larger, so that the method is not particularly limited;
s5, the signal receiving end receives the signal, and the conventional steps of removing the cyclic prefix, FFT operation, channel estimation demodulation, channel decoding, inverse scrambling and the like are sequentially carried out to obtain the signal after inverse scrambling
Figure BDA0002471053870000051
In the method, the processing mechanisms of removing the cyclic prefix, FFT operation, channel estimation demodulation, channel decoding and inverse scrambling of the signal by the receiving end are the same as the processing mechanisms of removing the cyclic prefix, FFT operation, channel estimation demodulation, channel decoding and inverse scrambling of the traditional OFDM signal during receiving, and the steps are not the innovation points of the invention and are not repeated;
s6, reversely and circularly moving the inversely scrambled signal S
Figure BDA0002471053870000052
The bit, i.e. the direction of the cyclic shift is opposite to the direction of the cyclic shift in step S1, corresponds to the inverse operation,
Figure BDA0002471053870000053
the initial value of (a) is 0; for example, in the case of a liquid,
Figure BDA0002471053870000054
time-shifted right signal
Figure BDA0002471053870000055
S7, performing CRC operation on the signals (such as S _ 1) after the reverse cyclic movement, if the check results are all 0, determining that the packet signals sent by the sending end are correctly received, finishing signal receiving, and reporting the signals (such as S _ 1) after the cyclic movement to a high-level processing; if the check result is not 0, the packet signal sent by the sending end is not received correctly, and step S8 is executed;
s8, judging
Figure BDA0002471053870000061
Whether or not it is greater than W, if
Figure BDA0002471053870000062
If it is greater than W, it is judged that this time signal receiving is wrong, signal receiving is finished, error is reported to high layer, otherwise, order is given
Figure BDA0002471053870000063
Returning to the step S6; and when the CRC results of the circularly moved signals are all 0 or the number of the circulation times exceeds W, ending the receiving process of the signals.
The set threshold C is a dynamic parameter, and is flexibly adjusted according to the number of subcarriers, the modulation mode and the performance of a power amplifier, when the set threshold C is larger, a sending end tries a small number of times of cyclic shift on an information bit signal to generate an OFDM signal meeting the requirement, the calculated amount is smaller, but the peak-to-average ratio of the OFDM signal is higher; when the set threshold C is smaller, the peak-to-average ratio of the transmitted signal is lower, but more attempts are needed to generate the OFDM signal that meets the requirement, and the calculation amount is larger. Therefore, the value of the set threshold value C is not specifically limited, and can be set by each equipment manufacturer according to the self condition in the actual application process.
For one OFDM signal, the frequency domain input signal of the communication system is X = [ X = [ X ] 1 ,X 2 ,…,X N ]The time domain signal sequence of the communication system is x = [ x = [ ] 1 ,x 2 ,…,x N ],
Figure BDA0002471053870000064
N =1,2, …, N is the number of subcarriers contained in the OFDM signal. Peak to average ratio of signal
Figure BDA0002471053870000065
Max (| x) in the formula n | 2 ) Representing the maximum value of the signal power, E (| x) n | 2 ) Representing the average power of the signal.
In general, a time domain Complementary Cumulative Distribution Function (CCDF) is used to describe the distribution of a signal peak-to-average ratio (PAPR), and the mathematical calculation formula is: pr (PAPR > z) =1-Pr (PAPR ≦ z).
According to the central limit theorem, the essence of the OFDM signal that the peak-to-average ratio occurs is that after the IFFT transformation is performed on the N frequency domain input signals, the obtained time domain signal tends to gaussian distribution, which becomes closer with the increase of the N value and the increase of the modulation order, and the gaussian distribution function has tail regions on the left and right sides, so that the time domain signal has a large value with a small probability.
The performance of the method for reducing the peak-to-average ratio of a signal is generally measured in the following 5 aspects: 1) The amount of sideband information; 2) The effect on transmission rate; 3) Signal reception performance; 4) Complexity of the algorithm; 5) The peak-to-average ratio of the transmitted signals decreases.
From the view of the amount of the sideband information, it can be seen from the signal processing flow of the method of the present invention that the receiving end can still perform the related processing flow on the received signal without any auxiliary information, so the amount of the sideband information is 0.
In view of the influence on the transmission rate, the method provided by the invention is used for optimally selecting the signal, the number of information bits carried by the signal is the same as that of the signal which is not processed by the method provided by the invention, and therefore, the transmission rate of the signal is not influenced.
The system packet signal transmission success rate, algorithm complexity, and the transmission signal peak-to-average ratio reduction level are analyzed in detail below.
1. Packet signal transmission success rate performance
Compared with the traditional OFDM signal, the signal processed by the method of the invention has the advantages that the signal processing process shows that the signal processing process only has a difference in the sending sequence of the two signals on the information bit level, and other signal processing links are consistent, so that the error probability of each information bit after decoding is the same under the condition of the same channel. It can be seen from the CRC check principle that if the information bit signals obtained after the inverse scrambling operation at the receiving side have error bits and the error bits are still within the range of the CRC check capability, the CRC check result will be shown as an erroneous reception regardless of the conventional signal or the signal processed by the method of the present invention, and therefore, the two types of CRC check performance are the same when the decoding result of the information bits is erroneous. If the decoding results of the two signals have no error, the traditional OFDM signal can ensure the correct reception of the grouped signal, and the signal processed by the method of the invention can be misjudged in a special scene that the actual transmission signal of the transmitting end is the information bit signal S = [ S ] = 1 ,...,s L ],s l =0 or 1,l =1, L, the signal S = [ S ] after L has passed a number of movements a times A+1 ,...,s L ,s 1 ,...,s A ],s l L, =0 or 1,l =1, but in the following group a-1 signals
Figure BDA0002471053870000071
Present in 1 or more than 1 groupUnder the condition that the last R bits of the signal are just the same as the CRC bits of the previous L-R bits, no error occurs in the decoding result of the information bits in the condition, but the receiving end reports an error packet signal to the higher layer. However, in general, the CRC check bit length R of uncoded information bits of a sending packet signal is more than or equal to 16 bits, and after a large amount of simulation, the inventor finds that the probability of the scene appearing in the information bit signal is less than 10 when A is less than or equal to 15, R is more than or equal to 16bits, and L is more than or equal to 100 bits -6 Therefore, after comprehensive analysis, it can be known that, under the same channel environment, the packet signal transmission success rate performance after the optimization mechanism is adopted tends to be consistent with that of the traditional signal.
2. Complexity of algorithm
It can be seen from the signal processing flow of the method of the present invention that the algorithm complexity is closely related to the setting size of the set threshold C. If the value of the set threshold value C is set to be 0, the algorithm complexity reaches the highest, namely, when the signal is sent each time, the sending end needs the data load data to carry out W times of signal processing flows including scrambling, coding, modulation and the like, so the algorithm complexity is W times when a peak-to-average ratio reduction mechanism is not adopted; if the value of the set threshold value C is set to infinity, the algorithm complexity is the lowest, the sending end only needs to perform 1 signal processing procedure on the data load data, and obviously, the peak-to-average ratio performance of the signal is not optimized at this time.
In the following, theoretical analysis of algorithm complexity is given by a time domain Complementary Cumulative Distribution Function (CCDF), and a threshold is set to be C, whereas in one signal transmission, a transmitting end needs to transmit K OFDM symbols in a data payload portion, and values of the K OFDM symbols are independent of each other, so that a probability value that a square of an amplitude maximum value in the K OFDM symbols is greater than C is:
pr { the square of the maximum value of the amplitudes of K OFDM symbols is greater than C } = 1-KxPr (PA ≦ C).
Considering that the cyclic shift operation can significantly change the transmission order of the information sequence bits, and then the non-linear operations such as scrambling and channel coding are performed, it can be considered that the series of signals generated based on the signal S and the cyclically shifted signal are independent from each other, and therefore when the threshold is set at the transmitting end as C, the probability value distribution of the cyclic shift value X (assumed as left shift) of the transmitted signal is as follows:
TABLE 1 probability values corresponding to different cycle left-shift values X
Figure BDA0002471053870000081
Figure BDA0002471053870000091
In general, the time-domain Complementary Cumulative Distribution Function (CCDF) of the transmitted signal of interest will be compared at 10 when evaluating the signal peak-to-average ratio (PAPR) case -4 The corresponding numerical value. Therefore, the transmitting end may set the value of the set threshold C to be 10 for the time-domain Complementary Cumulative Distribution Function (CCDF) corresponding to the current signal transmission -4 The corresponding value, i.e. Pr (PAPR > C) =1-Pr (PAPR ≦ C) =10 -4 (the value can be obtained by a computer through simulation), and the probability value conditions corresponding to the selection times of different scrambling seeds are as follows:
table 2 Pr (PAPR > C) =10 -4 Probability value corresponding to cycle left shift value X of time-division transmission signal
Figure BDA0002471053870000092
When the channel bandwidth is large, the number K of OFDM symbols in one packet signal transmission is generally on the order of several tens of OFDM symbols, and in this case, pr (PAPR > C) =10 -4 When the time is long, the probability value of occurrence of an event with W =0 is very small, so that the transmitting end keeps the same signal processing flow as the original algorithm in about 99% of cases, and the probability value of occurrence of the event with W =0>In the case of 0, W times more signal processing is required. Therefore, in summary, the method of the present invention hardly increases the computational complexity.
3. Simulation result of signal peak-to-average ratio reduction performance
The following gives a case of Complementary Cumulative Distribution Function (CCDF) of OFDM transmission signal when packet signal containing CRC check bits has an information bit length of 1024 bits, and a communication system has 1024 subcarriers and adopts a transmission scheme of 1/2turbo coding + QPSK modulation, in which scrambling sequence is randomly generated by a computer, and the upper limit value W =0,1,3,7,15 times of information bit cyclic shift (left shift) is as shown in fig. 4. From simulation results, it can be seen that, as the upper limit of the left-shift times of the loop increases, the optimization selection space of the transmitting end increases more and more, so that the performance optimization capability of the peak-to-average ratio value is better, and when W =15, the complementary cumulative distribution function of the peak-to-average ratio value of the transmission signal is 10 -4 About 4dB of peak-to-average power ratio is reduced, and a very good effect of reducing the peak-to-average power ratio is obtained.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present 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 spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (2)

1. A method for reducing the peak-to-average ratio of an OFDM signal, comprising the steps of:
s1, at a signal sending end, circularly moving a binary information bit stream signal corresponding to a packet signal to be sent by X bits, wherein the initial value of X is 0;
s2, scrambling, channel coding, constellation mapping, pilot frequency insertion and IFFT calculation are carried out on the binary information bit stream signal after the cyclic shift, and a signal containing K OFDM symbols is obtained, wherein K is the number of the OFDM symbols in one-time grouping signal transmission;
s3, respectively calculating the peak-to-average ratio values of K OFDM symbols, selecting the maximum value from the K OFDM symbols as the peak-to-average ratio value of the binary information bit stream signal after the cyclic shift, comparing the maximum value PAPR1 of the peak-to-average ratio value with a set threshold value C, if the maximum value PAPR1 of the peak-to-average ratio value is not more than the set threshold value C, considering that the peak-to-average ratio value of the signal to be transmitted meets the requirement, entering a subsequent signal processing flow and transmitting, and if the maximum value PAPR1 of the peak-to-average ratio value is more than the set threshold value C, entering a step S4;
s4, judging whether X is larger than W, if X is larger than W, selecting a binary information bit stream signal with the minimum peak-to-average ratio from the generated binary information bit stream signals after cyclic shift, and entering a subsequent signal processing flow and transmitting; otherwise, let X = X +1, and return to step S1, where W is the upper limit value of the information bit cyclic shift times; when the peak-to-average ratio of the generated binary information bit stream signal after cyclic shift is less than or equal to a set threshold value C, or the cycle number exceeds W, the transmission process of the signal is finished;
s5, a signal receiving end receives the signal, and conventional steps such as cyclic prefix removal, FFT operation, channel estimation demodulation, channel decoding, inverse scrambling and the like are sequentially carried out to obtain an inverse scrambled signal;
s6, reversely and circularly moving the inversely scrambled signals
Figure FDA0002471053860000014
The number of bits is,
Figure FDA0002471053860000015
is 0;
s7, performing CRC operation on the signals after reverse cyclic movement, and if the check results are all 0, determining that the packet signals sent by the sending end are correctly received, and ending signal receiving; if the check result is not 0, the packet signal sent by the sending end is not received correctly, and step S8 is executed;
s8, judging
Figure FDA0002471053860000011
Whether or not it is greater than W, if
Figure FDA0002471053860000013
If the signal is larger than W, the signal is considered to be received incorrectlyIf not, the signal reception is finished, otherwise, the instruction is
Figure FDA0002471053860000012
Returning to the step S6; and when the CRC results of the signals after the cyclic shift are all 0 or the cycle number exceeds W, ending the receiving process of the signals.
2. The method of reducing the peak-to-average ratio of an OFDM signal of claim 1, wherein: and at a signal sending end, circularly shifting left or circularly shifting right the binary information bit stream signal corresponding to the packet signal to be sent, wherein the directions of the circular shifting are consistent for the binary information bit stream signal corresponding to the same packet signal to be sent.
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