A carrier frequency offset blind estimation method, system and device for digital signal

Abstract

The application discloses a carrier frequency offset blind estimation method, system and device of a digital signal, mainly relates to the technical field of digital signals, and aims to solve the problem that the existing method cannot check unknown types of digital signals. It comprises the following steps: obtaining a first maximum power value and a first average value, and then determining a first frequency offset position and a first peak-to-average ratio; obtaining a second maximum power value and a second average value, and then determining a second frequency offset position and a second peak-to-average ratio; determining a plurality of power values; determining a threshold value based on a preset threshold calculation formula and the power values; determining the number of extreme values greater than the threshold value; determining a third frequency offset position and a third peak-to-average ratio based on the number of extreme values; and obtaining a frequency offset. The application realizes carrier frequency offset estimation of a baseband signal with an unknown modulation mode through the above method, and solves the problem that the frequency offset of a signal with a known modulation mode can only be estimated in the prior art.

Description

Technical Field

[0001] This application relates to the field of digital signals, and particularly to a method, system, and device for carrier frequency offset blind estimation of digital signals. Background Technology

[0002] In wireless communication systems, with the rapid development of software-defined radio technology and digital signal processing technology, all-digital modulation and demodulation technology has been widely used. Currently, commonly used digital modulation methods include 2 / 4ASK, GMSK, BPSK, QPSK, 8PSK, 16 / 32 / 64 / 128 / 256QAM, and OFDM. For the receiver end of the system, carrier frequency offset has a very negative impact on the communication system, not only causing constellation rotation but also drastically increasing the bit error rate. Therefore, carrier frequency offset estimation is one of the prerequisites for correct demodulation of digital signals.

[0003] At present, the main carrier frequency offset estimation schemes are: (1) Pi / 8D8PSK method: digital quadrature downconversion and low-pass filtering are performed on the Pi / 8D8PSK intermediate frequency signal to obtain the baseband signal modulated by Pi / 8D8PSK. The quadratic timing recovery algorithm is used to perform bit synchronization operation on the baseband signal. The data after bit synchronization is windowed to reduce energy leakage. The windowed data is then subjected to FFT operation after 16-fold operation. The modulus of the FFT operation result is calculated, and the frequency point corresponding to the maximum value is multiplied by the resolution bandwidth and then divided by 16 to obtain the frequency offset estimate. (2) QAM method: the fourth power operation is performed on it and then FFT operation is performed. The modulus of the FFT operation result is calculated, and the maximum value is obtained to obtain the frequency offset estimate. Then the WPH algorithm is used to calculate the phase histogram to obtain a more accurate frequency offset.

[0004] However, the Pi / 8D8PSK method described above does not support QPSK / QAM signals, making blind estimation impossible, and it requires 16th-power calculations, resulting in a large computational load. The QAM method only supports QAM signals, and in practical applications, it does not perform well for 32QAM / 128QAM signals. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a carrier frequency offset blind estimation method, system and device for digital signals to solve the above-mentioned technical problems.

[0006] In a first aspect, this application provides a blind estimation method for carrier frequency offset of digital signals. The method includes: performing 32-fold sampling, 8-fold power operation, and FFT operation on IQ data to obtain a first maximum power value and a first mean value, thereby determining a first frequency offset position and a first peak-to-average ratio (PAR); performing 32-fold sampling, 12-fold power operation, and FFT operation on IQ data to obtain a second maximum power value and a second mean value, thereby determining a second frequency offset position and a second PAR; performing 8-fold sampling, 4-fold power operation, and FFT operation on IQ data to determine several power values; determining a threshold value based on a preset threshold calculation formula and the power values; determining the number of extreme values ​​greater than the threshold value; determining a third frequency offset position and a third PAR based on the number of extreme values; and obtaining the frequency offset according to the first frequency offset position, the first PAR, the second frequency offset position, the second PAR, the third frequency offset position, the third PAR, and the preset frequency offset calculation formula.

[0007] Further, the IQ data is sampled 32 times, raised to the power of 8, and subjected to an FFT operation to obtain the first maximum power value and the first mean, thereby determining the first frequency offset position and the first peak-to-average ratio. Specifically, this includes: sampling the given IQ data 32 times to obtain 4096 IQ data points tmp_i and tmp_q, which together form the complex number signal_tmp; raising signal_tmp to the power of 8 to obtain signal_tmp8; performing an FFT operation on signal_tmp8 and then performing an FFTshift to obtain fft_sig_tmp_1; calculating the power value of fft_sig_tmp_1 to obtain fft_sig_1; calculating the maximum value peak1 and the mean1 of fft_sig_1, and simultaneously recording the peak position ind1 as the first frequency offset position; based on the formula: peak_mean_ratio1 = (peak1*1024 / mean(fft_sig_1)) is used to obtain the first peak-to-mean ratio; where mean is the mean operation and max is the maximum value operation.

[0008] Furthermore, the IQ data is sampled 32 times, raised to the power of 12, and subjected to an FFT operation to obtain the second maximum power value and the second mean, thereby determining the second frequency offset position and the second peak-to-average ratio. Specifically, this includes: sampling the given IQ data 32 times to obtain 4096 IQ data points tmp_i and tmp_q, which together form the complex number signal_tmp; raising signal_tmp to the power of 12 to obtain signal_tmp12; performing an FFT operation on signal_tmp12 and then performing an FFTshift to obtain fft_sig_tmp_2; calculating the power value of fft_sig_tmp_2 to obtain fft_sig_2; calculating the maximum value peak2 and the mean value mean2 of fft_sig_2, and recording the peak position ind2 as the second frequency offset position; and obtaining the second peak-to-average ratio based on the formula: peak_mean_ratio2 = (peak2*1024 / mean(fft_sig_2)).

[0009] Further, the IQ data is sampled 8 times, raised to the fourth power, and subjected to FFT to determine several power values; based on the preset threshold calculation formula and power values, a threshold value is determined; the number of extreme values ​​greater than the threshold value is determined; based on the number of extreme values, the third frequency offset position and the third peak-to-average power ratio are determined, specifically including: sampling the given IQ data 8 times to obtain 4096 IQ data points tmp_i_1 and tmp_q_1, tmp_i_1 and tmp_q_1 form the complex number signal_tmp_1; raising signal_tmp_1 to the fourth power to obtain signal_tmp4; performing FFT on signal_tmp4 and performing FFTshift to obtain fft_sig_tmp_3; calculating the power value of fft_sig_tmp_3 to obtain fft_sig_3; based on the preset threshold calculation formula: noise_th=mean(fft_sig_3)*8, max_sig_th = Given `max(fft_sig_3) / 4` and `sn_th=max(noise_th,max_sig_th)`, `sn_th` is the threshold value. Within `fft_sig_3`, all extreme values ​​greater than `sn_th` are identified, yielding the extreme value index `max_idx` and the number of extreme values ​​`cnt`. When `cnt=3`, the midpoint of `max_idx` is taken as the frequency offset point, and the corresponding value is determined to be `peak0`. The corresponding position `ind0` is determined as the third frequency offset position. Otherwise, when `cnt>=1`, the maximum value among the extreme values ​​is taken as the frequency offset point, and the corresponding value is determined to be `peak0`. The corresponding position `ind0` is determined as the third frequency offset position. Based on the formula: `peak_mean_ratio0= (peak0*1024 / mean(fft_sig_3))`, the third peak-to-mean ratio is obtained.

[0010] Furthermore, based on the first frequency offset position, the first peak-to-average power ratio (PAPR), the second frequency offset position, the second PAPR, the third frequency offset position, the third PAPR, and the preset frequency offset calculation formula, the frequency offset is obtained. Specifically, this includes: determining the maximum value among the first PAPR, the second PAPR, and the third PAPR as ind; when ind is ind0, setting power=4 and seata=8; when ind is ind1, setting power=8 and seata=32; when ind is ind2, setting power=12 and seata=32; and obtaining the frequency offset based on the preset frequency offset calculation formula: freq_offset=(ind-2049)*fs / 4096 / power / sita.

[0011] Secondly, this application provides a carrier frequency offset blind estimation system for digital signals. The system includes: a preset 8PSK submodule, used to perform 32x sampling, 8th power operation, and FFT operation on IQ data to obtain a first maximum power value and a first mean value, thereby determining a first frequency offset position and a first peak-to-average ratio (PAR); a preset 32 / 128QAM submodule, used to perform 32x sampling, 12th power operation, and FFT operation on IQ data to obtain a second maximum power value and a second mean value, thereby determining a second frequency offset position and a second PAR; a preset estimation submodule, used to perform 8x sampling, 4th power operation, and FFT operation on IQ data to determine several power values; a threshold value is determined based on a preset threshold calculation formula and the power values; the number of extreme values ​​greater than the threshold value is determined; a third frequency offset position and a third PAR are determined based on the number of extreme values; and a frequency offset correction submodule, used to obtain the frequency offset according to the first frequency offset position, the first PAR, the second frequency offset position, the second PAR, the third frequency offset position, the third PAR, and the preset frequency offset calculation formula.

[0012] Furthermore, the system also includes an input module, which simultaneously inputs IQ data into a preset 8PSK submodule, a preset 32 / 128QAM submodule, and a preset estimation submodule.

[0013] Thirdly, this application provides a carrier frequency bias blind estimation device for digital signals, the device comprising: a processor; and a memory storing executable code thereon, which, when executed, causes the processor to perform a carrier frequency bias blind estimation method for digital signals as described above.

[0014] Those skilled in the art will understand that the present invention has at least the following beneficial effects:

[0015] Since signals can be categorized into various types, such as 8PSK, 32 / 128QAM, and 2ASK / 4ASK / 2PSK / 4PSK / GMSK, this application calculates the correlation characteristics (peak-to-average power ratio and frequency offset) of the input signal in three parallel processes. Then, the correlation characteristics are compared, and the one with the best correlation to the signal type is selected from the three parallel processes to obtain the final frequency offset value. This achieves carrier frequency offset estimation for baseband signals with unknown modulation schemes, solving the problem that previous patents could only estimate the frequency offset of signals with known modulation schemes. The implementation scheme of this invention has low computational complexity, making it particularly suitable for FPGAs or DSPs. It can perform blind estimation of carrier frequencies for various digital signals with high accuracy (if higher accuracy is required, the sampling rate can be reduced and the number of FFT points increased). Attached Figure Description

[0016] The following description refers to some embodiments of this disclosure, in which:

[0017] Figure 1This is a flowchart of a carrier frequency offset blind estimation method for digital signals provided in an embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the internal structure of a carrier frequency offset blind estimation system for digital signals provided in an embodiment of this application.

[0019] Figure 3 This is a schematic diagram of the internal structure of a carrier frequency offset blind estimation device for digital signals provided in an embodiment of this application. Detailed Implementation

[0020] Those skilled in the art should understand that the embodiments described below are merely preferred embodiments of this disclosure and do not imply that this disclosure can only be implemented through these preferred embodiments. These preferred embodiments are merely used to explain the technical principles of this disclosure and are not intended to limit the scope of protection of this disclosure. Based on the preferred embodiments provided by this disclosure, all other embodiments obtained by those skilled in the art without creative effort should still fall within the scope of protection of this disclosure.

[0021] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0022] The technical solutions proposed in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0023] This application also provides a carrier frequency offset blind estimation method for digital signals, such as... Figure 1 As shown in the embodiments of this application, the method mainly includes the following steps:

[0024] Step 111: Perform 32x sampling, 8th power operation, and FFT operation on the IQ data to obtain the first maximum power value and the first mean value, and then determine the first frequency offset position and the first peak-to-average power ratio.

[0025] Specifically, the process can be as follows: The given IQ data is sampled 32 times to obtain 4096 IQ data points tmp_i and tmp_q. tmp_i and tmp_q form the complex number signal_tmp. Signal_tmp is then raised to the power of 8 to obtain signal_tmp8. FFT operations are performed on signal_tmp8, followed by FFT shift operations, to obtain fft_sig_tmp_1. The power value of fft_sig_tmp_1 is calculated to obtain fft_sig_1. The maximum value peak1 and mean value mean1 of fft_sig_1 are calculated, and the peak position ind1 is recorded as the first frequency offset position. Based on the formula: peak_mean_ratio1 = (peak1*1024 / mean(fft_sig_1)), the first peak-to-mean ratio is obtained; where mean is the mean operation and max is the maximum value operation.

[0026] It should be noted that, based on the characteristics of 8PSK signals, the peak-to-average power ratio (PAPR) of 8PSK signals calculated using this estimation method is much higher than that of other signals, and it can calculate 8PSK signals better.

[0027] Step 112: Perform 32x sampling, 12th power operation, and FFT operation on the IQ data to obtain the second maximum power value and the second mean value, and then determine the second frequency offset position and the second peak-to-average power ratio.

[0028] Specifically, the process can be as follows: The given IQ data is sampled 32 times to obtain 4096 IQ data points tmp_i and tmp_q. tmp_i and tmp_q form the complex number signal_tmp. Signal_tmp is then raised to the power of 12 to obtain signal_tmp12. FFT operations are performed on signal_tmp12, followed by FFT shift, to obtain fft_sig_tmp_2. The power value (square of the amplitude) of fft_sig_tmp_2 is calculated to obtain fft_sig_2. The maximum value peak2 and mean value mean2 of fft_sig_2 are calculated, and the peak position ind2 is recorded as the second frequency offset position. Based on the formula: peak_mean_ratio2 = (peak2*1024 / mean(fft_sig_2)), the second peak-to-mean ratio is obtained.

[0029] It should be noted that the frequency offset estimation of 32 / 128QAM is achieved by designing a 12th power spectrum and performing FFT operations. This solves the problem of inaccurate frequency offset estimation for this signal in previous patents. The peak-to-average power ratio calculated by the estimation method is much higher than that of other signals, and it can better calculate the 32 / 128QAM signal.

[0030] Step 113: Perform 8x sampling, 4th power operation, and FFT operation on the IQ data to determine several power values; determine the threshold value based on the preset threshold calculation formula and power value; determine the number of extreme values ​​greater than the threshold value; determine the third frequency offset position and the third peak-to-average power ratio based on the number of extreme values.

[0031] Specifically, the process can be as follows: the given IQ data is sampled 8 times to obtain 4096 IQ data points tmp_i_1 and tmp_q_1, and tmp_i_1 and tmp_q_1 form the complex number signal_tmp_1; signal_tmp_1 is raised to the fourth power to obtain signal_tmp4.

[0032] Perform an FFT operation on signal_tmp4 and then perform an FFTshift swap to obtain fft_sig_tmp_3; calculate the power value (square of the amplitude) of fft_sig_tmp_3 to obtain fft_sig_3; based on the preset threshold calculation formula: noise_th = mean(fft_sig_3) * 8, max_sig_th = max(fft_sig_3) / 4, sn_th = max(noise_th, max_sig_th), Obtain sn_th as the threshold value; identify all extreme values ​​greater than sn_th in fft_sig_3, and obtain the extreme value index max_idx and the number of extreme values ​​cnt; when cnt=3, take the midpoint of max_idx as the frequency offset point, determine the corresponding value as peak0, and determine the corresponding position as the third frequency offset position ind0; otherwise, when cnt>=1, take the maximum value among the extreme values ​​as the frequency offset point, determine the corresponding value as peak0, and determine the corresponding position as the third frequency offset position ind0; based on the formula: peak_mean_ratio0= (peak0*1024 / mean(fft_sig_3)), obtain the third peak-to-mean ratio.

[0033] It should be noted that this estimation method is based on the characteristics of 2ASK / 4ASK / 2PSK / 4PSK / GMSK signals. The peak-to-average power ratio (PAPR) of 2ASK / 4ASK / 2PSK / 4PSK / GMSK signals calculated using this method is much higher than that of other signals.

[0034] Step 120: Obtain the frequency offset based on the first frequency offset position, the first peak-to-average power ratio, the second frequency offset position, the second peak-to-average power ratio, the third frequency offset position, the third peak-to-average power ratio, and the preset frequency offset calculation formula.

[0035] Specifically, the process can be as follows: determine the maximum value among the first peak-to-average power ratio (PAPR), the second PAPR, and the third PAPR as ind; when ind is ind0, set power=4 and seata=8; when ind is ind1, set power=8 and seata=32; when ind is ind2, set power=12 and seata=32; and obtain the frequency offset based on the preset frequency offset calculation formula: freq_offset=(ind-2049)*fs / 4096 / power / sita.

[0036] besides, Figure 2 This application provides a carrier frequency offset blind estimation system for digital signals. For example... Figure 2 As shown in the embodiments of this application, the system mainly includes:

[0037] The preset 8PSK submodule 211 is used to perform 32x sampling, 8th power operation, and FFT operation on IQ data to obtain the first maximum power value and the first mean value, thereby determining the first frequency offset position and the first peak-to-average power ratio.

[0038] A preset 32 / 128QAM submodule 212 is used to perform 32x sampling, 12th power operation, and FFT operation on the IQ data to obtain the second maximum power value and the second average value, thereby determining the second frequency offset position and the second peak-to-average power ratio.

[0039] The preset estimation submodule 213 is used to perform 8x sampling, 4th power operation, and FFT operation on IQ data to determine several power values; determine the threshold value based on the preset threshold calculation formula and power value; determine the number of extreme values ​​greater than the threshold value; and determine the third frequency offset position and the third peak-to-average power ratio based on the number of extreme values.

[0040] The frequency offset correction submodule 220 is used to obtain the frequency offset based on the first frequency offset position, the first peak-to-average power ratio, the second frequency offset position, the second peak-to-average power ratio, the third frequency offset position, the third peak-to-average power ratio, and a preset frequency offset calculation formula.

[0041] In addition, the system also includes an input module 230, which is used to simultaneously input IQ data into a preset 8PSK submodule, a preset 32 / 128QAM submodule, and a preset estimation submodule.

[0042] In addition, embodiments of this application also provide a carrier frequency offset blind estimation device for digital signals, such as... Figure 3 As shown, it stores executable instructions, which, when executed, implement a carrier frequency offset blind estimation method for digital signals as described above. Specifically, the server sends execution instructions to the memory via the bus. When the memory receives the execution instructions, it sends an execution signal to the processor via the bus to activate the processor.

[0043] It should be noted that the processor performs 32x sampling, 8th power operation, and FFT operation on the IQ data to obtain the first maximum power value and the first mean value, thereby determining the first frequency offset position and the first peak-to-average power ratio (PAPR); performs 32x sampling, 12th power operation, and FFT operation on the IQ data to obtain the second maximum power value and the second mean value, thereby determining the second frequency offset position and the second PAPR; performs 8x sampling, 4th power operation, and FFT operation on the IQ data to determine several power values; determines the threshold value based on the preset threshold calculation formula and the power value; determines the number of extreme values ​​greater than the threshold value; determines the third frequency offset position and the third PAPR based on the number of extreme values; and obtains the frequency offset according to the first frequency offset position, the first PAPR, the second frequency offset position, the second PAPR, the third frequency offset position, the third PAPR, and the preset frequency offset calculation formula.

[0044] The technical solutions of this disclosure have been described in conjunction with the preceding embodiments. However, it will be readily understood by those skilled in the art that the scope of protection of this disclosure is not limited to these specific embodiments. Without departing from the technical principles of this disclosure, those skilled in the art can disassemble and combine the technical solutions in the above embodiments, and can also make equivalent changes or substitutions to the relevant technical features. Any changes, equivalent substitutions, improvements, etc., made within the technical concept and / or technical principles of this disclosure will fall within the scope of protection of this disclosure.

Claims

1. A carrier frequency offset blind estimation method for digital signals, characterized in that, The method includes: The IQ data is sampled 32 times, raised to the power of 8, and subjected to FFT to obtain the first maximum power value and the first mean value, thereby determining the first frequency offset position and the first peak-to-average power ratio. The IQ data is sampled 32 times, raised to the power of 12, and subjected to FFT to obtain the second maximum power value and the second mean value, thereby determining the second frequency offset position and the second peak-to-average power ratio. The IQ data is sampled 8 times, raised to the fourth power, and subjected to FFT to determine several power values; based on the preset threshold calculation formula and the power values, a threshold value is determined; the number of extreme values ​​greater than the threshold value is determined; and the third frequency offset position and the third peak-to-average power ratio are determined based on the number of extreme values. The frequency offset is obtained based on the first frequency offset position, the first peak-to-average power ratio (PAPR), the second frequency offset position, the second PAPR, the third frequency offset position, the third PAPR, and the preset frequency offset calculation formula.

2. The carrier frequency offset blind estimation method for digital signals according to claim 1, characterized in that, The IQ data is sampled 32 times, raised to the 8th power, and subjected to FFT to obtain the first maximum power value and the first mean value, thereby determining the first frequency offset position and the first peak-to-average power ratio, specifically including: The given IQ data is sampled 32 times to obtain 4096 IQ data points tmp_i and tmp_q. tmp_i and tmp_q form the complex number signal_tmp. Powering signal_tmp to the power of 8 results in signal_tmp8; Perform an FFT operation on signal_tmp8 and then perform an FFTshift swap to obtain fft_sig_tmp_1; Calculate the power value of fft_sig_tmp_1 to obtain fft_sig_1; Calculate the maximum value peak1 and mean value mean1 of fft_sig_1, and record the peak position ind1 as the first frequency offset position; Based on the formula: peak_mean_ratio1 = (peak1*1024 / mean(fft_sig_1)), the first peak-mean ratio is obtained; where mean is the mean operation and max is the maximum value operation.

3. The carrier frequency offset blind estimation method for digital signals according to claim 1, characterized in that, The IQ data is sampled 32 times, raised to the power of 12, and subjected to FFT to obtain the second maximum power value and the second mean value. This allows for the determination of the second frequency offset position and the second peak-to-average power ratio, specifically including: The given IQ data is sampled 32 times to obtain 4096 IQ data points tmp_i and tmp_q. tmp_i and tmp_q form the complex number signal_tmp. Powering signal_tmp to the power of 12 results in signal_tmp12; Perform an FFT operation on signal_tmp12 and then perform an FFTshift swap to obtain fft_sig_tmp_2; Calculate the power value of fft_sig_tmp_2 to obtain fft_sig_2; Calculate the maximum value peak2 and mean value mean2 of fft_sig_2, and record the peak position ind2 as the second frequency offset position; Based on the formula: peak_mean_ratio2 = (peak2*1024 / mean(fft_sig_2)), the second peak-to-mean ratio is obtained.

4. The carrier frequency offset blind estimation method for digital signals according to claim 1, characterized in that, The IQ data is sampled 8 times, raised to the fourth power, and subjected to FFT to determine several power values; a threshold value is determined based on a preset threshold calculation formula and the power values. Determine the number of extreme values ​​that are greater than the threshold value; The location of the third frequency offset and the third peak-to-average power ratio are determined based on the number of extreme values, specifically including: The given IQ data is sampled 8 times to obtain 4096 IQ data points tmp_i_1 and tmp_q_1. tmp_i_1 and tmp_q_1 form the complex number signal_tmp_1. Powering signal_tmp_1 to the fourth power yields signal_tmp4; Perform an FFT operation on signal_tmp4 and then perform an FFTshift swap to obtain fft_sig_tmp_3; Calculate the power value of fft_sig_tmp_3 to obtain fft_sig_3; Based on the preset threshold calculation formula: noise_th=mean(fft_sig_3)*8, max_sig_th = max(fft_sig_3) / 4, sn_th=max(noise_th,max_sig_th), sn_th is obtained as the threshold value; In fft_sig_3, identify all extreme values ​​greater than sn_th and obtain the extreme value index max_idx and the number of extreme values ​​cnt; When cnt=3, the midpoint of max_idx is taken as the frequency offset point, the corresponding value is determined to be peak0, and the corresponding position ind0 is determined to be the third frequency offset position; otherwise, when cnt>=1, the maximum value point among the extreme values ​​is taken as the frequency offset point, the corresponding value is determined to be peak0, and the corresponding position ind0 is determined to be the third frequency offset position. Based on the formula: peak_mean_ratio0 = (peak0*1024 / mean(fft_sig_3)), the third peak-mean ratio is obtained.

5. The carrier frequency offset blind estimation method for digital signals according to claim 1, characterized in that, The frequency offset is obtained based on the first frequency offset position ind1, the first peak-to-average power ratio (PAPR), the second frequency offset position ind2, the second PAPR, the third frequency offset position ind0, the third PAPR, and a preset frequency offset calculation formula. Specifically, this includes: Determine the maximum value among the first peak-to-average ratio, the second peak-to-average ratio, and the third peak-to-average ratio as ind; When ind is ind0, let power=4 and seata=8; When ind is ind1, let power=8 and seata=32; When ind is ind2, let power=12 and seata=32; The frequency offset is obtained based on the preset frequency offset calculation formula: freq_offset=(ind-2049)*fs / 4096 / power / sita, where fs is the sampling frequency.

6. A carrier frequency offset blind estimation system for digital signals, characterized in that, The system includes: An 8PSK submodule is pre-defined to perform 32x sampling, 8th power operation, and FFT operation on IQ data to obtain the first maximum power value and the first mean value, thereby determining the first frequency offset position and the first peak-to-average power ratio. A 32 / 128QAM submodule is preset to perform 32x sampling, 12th power operation, and FFT operation on IQ data to obtain the second maximum power value and the second mean value, thereby determining the second frequency offset position and the second peak-to-average power ratio. A preset estimation submodule is used to perform 8x sampling, 4th power operation, and FFT operation on IQ data to determine several power values; determine the threshold value based on the preset threshold calculation formula and the power value; determine the number of extreme values ​​greater than the threshold value; and determine the third frequency offset position and the third peak-to-average power ratio based on the number of extreme values. The frequency offset correction submodule is used to obtain the frequency offset based on the first frequency offset position, the first peak-to-average power ratio, the second frequency offset position, the second peak-to-average power ratio, the third frequency offset position, the third peak-to-average power ratio, and a preset frequency offset calculation formula.

7. The carrier frequency offset blind estimation system for digital signals according to claim 6, characterized in that, The system further includes an input module, used to simultaneously input IQ data into a preset 8PSK submodule, a preset 32 / 128QAM submodule, and a preset estimation submodule.

8. A carrier frequency offset blind estimation device for digital signals, characterized in that, The device includes: processor; And a memory having executable code stored thereon, which, when executed, causes the processor to perform a carrier frequency offset blind estimation method for a digital signal as described in any one of claims 1-5.

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