Frequency domain ZC sequence synchronization head design method capable of resisting ultra-large frequency difference

Abstract

A method for designing a frequency domain ZC sequence synchronization head resistant to ultra-large frequency difference belongs to the technical field of communication, and comprises the following steps: avoiding correlation peak ambiguity caused by overlarge frequency offset through piecewise iterative estimation and compensation of decimal frequency offset; a ZC sequence sideband protection design is adopted, so that a sideband part and a base sequence form a continuous structure, and the time synchronization robustness is improved; in combination with pilot frequency cross-correlation and self-correlation processing, a cross-correlation signal is divided into subsequences for conjugate multiplication and summation, and accurate estimation of integer frequency offset is realized. According to the invention, the synchronization reliability and the system spectrum efficiency can be remarkably improved, high-precision synchronization in an ultra-large frequency difference range is supported, and the synchronization problem in a high-speed mobile communication scene is effectively solved.

Description

Technical Field

[0001] This application relates to the field of communication technology, specifically to a design method for a frequency domain ZC sequence synchronization header that is resistant to ultra-large frequency differences. Background Technology

[0002] In Orthogonal Frequency Division Multiplexing (OFDM) communication systems, synchronization technology is crucial for ensuring system performance. Since OFDM relies on strict orthogonality between subcarriers for signal demodulation, the system places extremely high demands on time synchronization and carrier frequency synchronization. When space- and power-constrained devices such as mobile aircraft operate in complex multipath environments, the quality of synchronization directly determines communication reliability. Time synchronization requires precise positioning of the received signal's starting position to avoid inter-symbol interference (ISI), while carrier frequency synchronization needs to compensate for frequency differences caused by Doppler shifts due to crystal oscillator instability or relative device motion at the transmitting and receiving ends. Frequency differences are classified into integer multiples and fractional multiples based on the normalization of the subcarrier spacing: integer multiples do not destroy subcarrier orthogonality but cause spectral misalignment, leading to bit errors; fractional multiples directly destroy orthogonality, causing carrier-to-carrier interference (CCI).

[0003] Existing synchronization technologies have significant limitations. Time synchronization commonly employs PN sequence training methods, but under conditions of extremely large frequency differences (e.g., -180kHz) and low signal-to-noise ratios (e.g., -3dB), the correlation peaks attenuate severely, leading to synchronization failure. Although ZC sequences perform well at low signal-to-noise ratios due to their constant envelope and ideal autocorrelation characteristics, full-bandwidth design easily leads to bandwidth overflow. Fractional frequency offset estimation mainly relies on cyclic prefix or training sequence correlation methods; the former is affected by multipath channels and has low accuracy, while the latter has a limited estimation range. Integer frequency offset estimation techniques face multiple challenges: the frequency domain conjugate cross-correlation method requires two FFTs and depends on precise timing; the time domain correlation method, although reduced to one FFT, still requires precise timing; the frequency domain pilot correlation method is computationally simple but requires precise timing, and the pilot density increases system overhead; the frequency domain cross-correlation differential method, although tolerant of timing deviations, is difficult to apply in resource-constrained scenarios due to its high computational complexity. These shortcomings together make it difficult for existing solutions to meet the core requirements of adaptability to ultra-large frequency differences, robustness to low signal-to-noise ratios, low computational complexity, and zero system overhead in scenarios such as mobile devices and aircraft.

[0004] Therefore, an innovative synchronization design is urgently needed to ensure that the time synchronization sequence maintains a high correlation peak under ultra-large frequency difference, and that the integer multiple frequency offset estimation can still be accurately calculated when timing deviation exists without additional resources, while avoiding increasing system overhead. Summary of the Invention

[0005] This application provides a frequency domain ZC sequence synchronization header design method that is resistant to ultra-large frequency differences, which can solve the technical problems of synchronization header failure or severe reduction in synchronization accuracy under ultra-large frequency differences in the prior art.

[0006] In a first aspect, embodiments of this application provide a method for designing a frequency-domain ZC sequence synchronization header resistant to ultra-large frequency differences, the method comprising: The fractional frequency offset is estimated using the training sequence; fractional frequency offset compensation is performed on the received signal; the ZC sequence position is extracted from the compensated signal, the ZC sequence is extracted and correlated with the locally known reference ZC sequence; the peak position is determined from the correlation processing result as the time synchronization position; The complete signal frame is captured using the time synchronization position and a fast Fourier transform is performed. In the transformed data, the pilot subcarrier positions are extracted, and the cross-correlation between the pilot and the local pilot is calculated. Based on the cross-correlation results, autocorrelation processing is performed, including dividing the cross-correlation signal into two continuous subsequences and performing conjugate multiplication and summation. The position of the maximum value is determined from the summation result as the integer multiple frequency offset estimate.

[0007] In conjunction with the first aspect, in one implementation, the fractional octet frequency offset estimation specifically includes the following steps: Segment the training sequence; For each training sequence, perform an iterative search to estimate the fractional octave frequency offset.

[0008] In conjunction with the first aspect, in one embodiment, the ZC sequence includes a sideband protection design, wherein the sideband portions are located on both sides of the ZC base sequence.

[0009] In conjunction with the first aspect, in one embodiment, the ZC base sequence is repeated 1 time.

[0010] In conjunction with the first aspect, in one implementation, the pilot is a comb pilot designed for channel estimation.

[0011] In conjunction with the first aspect, in one implementation, the relevant processing specifically includes the following steps: Calculate the cross-correlation between the ZC sequence and the local reference ZC sequence; The peak positions of the cross-correlation results were determined.

[0012] In conjunction with the first aspect, in one implementation, the autocorrelation processing specifically includes the following steps: The cross-correlation signal is divided into two continuous subsequences; Perform conjugate multiplication on the two subsequences; sum the results of the multiplication.

[0013] In conjunction with the first aspect, in one implementation, the received signal is filtered to reduce the impact of noise before fractional frequency offset compensation is performed.

[0014] In conjunction with the first aspect, in one embodiment, the sideband protection design causes the sideband portion to form a continuous sequence structure with the ZC base sequence portion.

[0015] In conjunction with the first aspect, in one implementation, the distribution density of the comb pilot is associated with the subsequence partitioning parameters in the autocorrelation processing.

[0016] The beneficial effects of the technical solutions provided in this application include: This application's frequency-domain ZC sequence synchronization header design method for handling ultra-large frequency differences solves the technical problems of synchronization header failure or severe degradation of synchronization accuracy under ultra-large frequency differences in related technologies. By using piecewise iterative estimation and compensation of fractional-fold frequency offsets, it avoids excessive frequency offsets leading to blurred correlation peaks; the ZC sequence sideband protection design improves time synchronization robustness; and by using pilot-autocorrelation-cross-correlation combined with integer-fold frequency offset estimation, the cross-correlation signal is divided into sub-sequences for conjugate multiplication and summation, accurately locating the integer frequency offset. Thus, high-precision time synchronization and frequency offset compensation are achieved under ultra-large frequency difference conditions, significantly improving synchronization reliability and system demodulation performance. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating an embodiment of the frequency domain ZC sequence synchronization header design method for resisting ultra-large frequency differences in this application; Figure 2 This is a schematic diagram of the frame format of the improved ZC sequence in a specific embodiment of this application; Figure 3 This is a schematic diagram of the peak generation process in a specific embodiment of this application; Figure 4 This is a schematic diagram of the peak value in a specific embodiment of this application. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0020] In a first aspect, embodiments of this application provide a method for designing a frequency domain ZC sequence synchronization header that is resistant to ultra-large frequency differences.

[0021] In one embodiment, reference is made to Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the frequency domain ZC sequence synchronization header design method for resisting ultra-large frequency differences according to this application. Figure 1 As shown, the design method for frequency domain ZC sequence synchronization headers resistant to ultra-large frequency differences includes: Step S1: Estimate the fractional octave frequency offset using the training sequence; Step S2: Perform fractional-fold frequency offset compensation on the received signal; Step S3: Extract the ZC sequence position from the compensated signal, extract the ZC sequence, and perform correlation processing with the local known reference ZC sequence; Step S4: Determine the peak position from the relevant processing results as the time synchronization position; Step S5: Use the time synchronization position to capture the complete signal frame and perform a fast Fourier transform; Step S6: Extract the pilot subcarrier positions from the transformed data and calculate the cross-correlation between the pilot and the local pilot. Step S7: Based on the cross-correlation results, perform autocorrelation processing, including dividing the cross-correlation signal into two continuous subsequences and performing conjugate multiplication and summation; Step S8: Determine the position of the maximum value from the summation result as the integer multiple frequency offset estimate.

[0022] This embodiment solves the technical problem of synchronization head failure or severe reduction in synchronization accuracy under ultra-large frequency differences (such as -180kHz frequency offset and 3km / h speed) in related technologies. By segmented iterative estimation and compensation of fractional-fold frequency offsets, the ambiguity of correlation peaks caused by excessive frequency offsets is avoided. Through correlation processing of the ZC sequence and the local reference sequence, the precise determination of the time synchronization position is achieved. By combining pilot-autocorrelation and cross-correlation estimation of integer-fold frequency offsets (using multiplexed channel estimation of comb pilots, requiring only one FFT), the integer frequency offset is accurately located. Thus, high-precision time synchronization and frequency offset compensation are achieved under ultra-large frequency difference conditions, significantly improving synchronization reliability and system demodulation performance.

[0023] Furthermore, in one embodiment, the fractional octet frequency offset estimation specifically includes: Segment the training sequence; For each training sequence, perform an iterative search to estimate the fractional octave frequency offset.

[0024] In this embodiment, the training sequence position used for fractional-fold frequency offset estimation is extracted from the time-domain signal, and the training sequence signal is extracted. The original long training sequence is divided into multiple short segments (e.g., each segment is 1 / 4 of the original length) to reduce the phase rotation angle caused by frequency offset within each segment, thus avoiding the blurring and diffusion of related peaks due to excessive frequency offset.

[0025] For each training sequence, a traversal search is performed within a fractional multiple of the frequency offset using small step sizes. Assuming the divided training sequence is 256 points long, the first and second received training sequences are autocorrelated to calculate the first phase offset estimate. This first phase offset estimate yields an initial value for the carrier frequency offset, and the phase offset w1 at position 512 is obtained from this initial value. The first and third received training sequences are autocorrelated to calculate the second phase offset estimate, and the phase offset w2 at position 512 is obtained from this second phase offset estimate. The phase error diff = w1 - w2 at position 512 is calculated, and this error is used to correct the phase offset at position 512, yielding the corresponding frequency offset. The third process is similar, comparing the deviations between the phase errors obtained from the two different methods at the same point and correcting the frequency offset to obtain a more accurate carrier frequency offset. This effectively suppresses single-segment noise interference and improves the estimation robustness.

[0026] Furthermore, in one embodiment, the ZC sequence includes a sideband protection design, wherein the sideband portions are located on both sides of the ZC base sequence. The ZC base sequence is repeated once.

[0027] In this embodiment, sideband portions of the same origin as the base sequence are added to both sides of the ZC base sequence (such as periodic extension or linear interpolation of the ZC sequence) to make the entire sequence present a smooth transition in the frequency domain and eliminate spectral leakage at the boundary of the base sequence.

[0028] In one specific embodiment, a novel time synchronization correlator based on an improved ZC sequence is designed to handle integer frequency offsets. As a preferred embodiment of the invention, the time synchronization sequence consists of ZC_512, where ZC_512 is a 512-point improved ZC sequence (with a repetition count of 1). The ZC sequence is designed according to the ABA frame format as follows: Figure 2 As shown, A is the sideband and B is the ZC base sequence, with the sideband located on both sides of the ZC base sequence.

[0029] Continue to refer to Figure 2 A 512-point correlator sliding correlation will produce a single peak. When the channel is a 3-path channel, with a frequency offset of -180kHz, a speed of 3km / h, and an SNR of -3dB, as shown... Figure 4 As shown, the new time correlator still maintains a high correlation peak.

[0030] Simulation results show that the ZC sequence designed in this patent only requires a length of 512 points and a repetition count of 1, which can significantly reduce the computational complexity and achieve the comprehensive advantages of resisting ultra-large frequency difference, high correlation peak value and low peak-to-average ratio (PAPR) under low signal-to-noise ratio.

[0031] Furthermore, in one embodiment, the pilot is a comb pilot designed for channel estimation.

[0032] In this embodiment, the pilot subcarriers directly reuse the comb pilots already inserted during channel estimation. For example, in an OFDM system, comb pilots are inserted at fixed intervals (e.g., every 10 subcarriers) for each OFDM symbol during channel estimation. This scheme eliminates the need for additional pilot design, directly using these comb pilots for integer multiple frequency offset estimation, thus avoiding increased system overhead. This design ensures that the pilot distribution is consistent with channel estimation, without requiring modification to the existing channel estimation module.

[0033] Furthermore, in one embodiment, the related processing specifically includes the following steps: Calculate the cross-correlation between the ZC sequence and the local reference ZC sequence; The peak positions of the cross-correlation results were determined.

[0034] In this embodiment, the received signal is compensated for by a fractional multiple of the estimated frequency offset. The ZC sequence position used for time synchronization is extracted from the compensated signal. The ZC sequence is extracted and correlated with the local known reference ZC sequence. There will be a peak in the correlated data. The position of this peak is the signal time synchronization position.

[0035] By leveraging the periodicity of the ZC sequence, the cross-correlation between the received ZC sequence and the local reference sequence is calculated, generating a high signal-to-noise ratio correlation peak, which significantly reduces the impact of noise interference on peak identification. With the support of a continuous structure in the sideband protection design, the correlation peak width is narrowed, significantly reducing the peak position error and completely eliminating the risk of misjudgment caused by residual frequency offset.

[0036] Furthermore, in one embodiment, the autocorrelation processing specifically includes the following steps: The cross-correlation signal is divided into two continuous subsequences; Perform conjugate multiplication on the two subsequences; sum the results of the multiplication.

[0037] In this embodiment, the cross-correlation signal R1 is divided into two continuous subsequences R11 and R12 (R11 = R1(1:end-1), R12 = R1(2:end)); the conjugate multiplication of R11 and R12 yields signal R2; the summation of each sequence point in R2 yields signal R3. The peak position of R3 corresponds one-to-one with the integer multiples of the frequency offset, thereby achieving high-precision frequency offset estimation.

[0038] In one specific embodiment, a complete frame of signal is captured using the time synchronization location, and a Fast Fourier Transform (FFT) is performed on the signal. After the FFT, integer multiple frequency offset estimation is performed. The specific method for integer multiple frequency offset estimation is as follows: Extract the subcarrier positions of the pilot signals from the FFT output data and retrieve the received pilot subcarrier signals.

[0039] The signal R1 is obtained by multiplying the local pilot subcarrier with the conjugate of the received pilot subcarriers at different starting positions; Divide signal R1 into two signals R11 and R12, where R11 = R1(1:end-1). R12 = R1(2:end), multiplying the conjugates of signals R11 and R12 gives signal R2; Summing the sequence points in signal R2 yields signal R3; Find the position of the maximum value in R3, and denote it as indx; Find the indx with the highest probability among the indx sets of multiple symbols and use it as the integer frequency offset value.

[0040] The estimated integer multiples of the frequency offset are used for signal compensation. At this point, the synchronization of the entire OFDM system is complete.

[0041] Furthermore, in one embodiment, the received signal is filtered before fractional-fold frequency offset compensation to reduce noise impact.

[0042] In this embodiment, the received signal is filtered before fractional frequency offset compensation. By suppressing channel noise, the reliability of fractional frequency offset estimation is significantly improved, laying a high signal-to-noise ratio signal foundation for subsequent synchronization procedures.

[0043] Furthermore, in one embodiment, the sideband protection design enables the sideband portion to form a continuous sequence structure with the ZC base sequence portion.

[0044] In this embodiment, the sideband-protected continuous structure design, which forms a continuous sequence with the ZC base sequence, can eliminate boundary spectral leakage and solve the problem of decreased time synchronization robustness of traditional ZC sequences due to boundary abrupt changes.

[0045] Furthermore, in one embodiment, the distribution density of the comb pilot is associated with the subsequence partitioning parameters in the autocorrelation processing.

[0046] In this embodiment, the pilot distribution density (e.g., pilot spacing Δf) is strictly correlated with the subsequence length of the autocorrelation processing (e.g., R1 partitioning step size) (Δf = subsequence length × 1.2), ensuring that the periodicity of the cross-correlation signal R1 is perfectly aligned with the subsequence partitioning. This correlation design increases the peak amplitude of the signal R3 after conjugate multiplication and summation, improves the sidelobe suppression ratio, and completely eliminates multi-peak interference.

[0047] In one specific implementation, to address the ultra-large frequency difference synchronization problem of OFDM systems at a frequency offset of -180kHz (corresponding to a speed of 3km / h) and a signal-to-noise ratio of -3dB, a frequency domain ZC sequence synchronization header design method resistant to ultra-large frequency difference is adopted. First, a 512-point training sequence is extracted from the received signal and divided into four segments (128 points each). Fractional-fold frequency offsets (e.g., -179.8kHz) are estimated within a ±180kHz range through iterative search and compensated for. Second, a 512-point ABA-structured ZC sequence (with sidebands located on both sides of the base sequence and repetition count = 1) is extracted from the compensated signal and cross-correlated with the local reference sequence to determine the time synchronization position (time T1). At this point, the timing deviation caused by integer-fold frequency offsets does not affect peak identification (the correlation peak amplitude is 1.82 at -3dB SNR). Finally, based on the time synchronization position, a complete signal frame is extracted, and one FFT transformation is performed. The channel estimation comb pilot (uniformly distributed in the frequency domain, with an interval of Δf=10 subcarriers) is multiplexed, and the pilot-autocorrelation cross-correlation algorithm is executed: the cross-correlation signal R1 is divided into R11 and R12, and the conjugates are multiplied and summed to obtain R3. The peak position indx (e.g., -12) is taken as the integer multiple of the frequency offset value to complete the compensation. This synchronization process (after fractional multiples of the frequency offset, time synchronization is performed, and finally, integer multiples of the frequency offset are performed) requires only one FFT, which saves FPGA resources compared to the traditional method that requires two FFTs, and improves synchronization reliability at a frequency offset of -180kHz.

[0048] Examples of the synchronization sequence design are as follows: In OFDM systems, the sequence of synchronizations is designable and not fixed. This scheme first performs fractional-fold frequency offset estimation, then time synchronization, and finally integer-fold frequency offset estimation. The specific design approach is as follows: Time synchronization is performed before integer-multiple frequency offset estimation. This is because integer-multiple frequency offset estimation is performed in the frequency domain. After time synchronization and FFT operation, integer-multiple frequency offset estimation is performed before channel estimation, eliminating the need for a separate FFT operation and saving FPGA resources. Another reason is that integer-multiple frequency offset does not destroy subcarrier orthogonality; it only causes a cyclic shift in the signal. This cyclic shift is due to the frequency shift characteristics of the Fourier transform.

[0049] The complete synchronization sequence of this scheme is shown in formula (1): (1), in, This represents the k-th subcarrier in the frequency domain. Represents a time-domain signal. The frequency offset is represented by an integer multiple, and N represents the total length of the data.

[0050] In summary, traditional frequency-domain pilot correlation methods only calculate the cross-correlation of pilots. While computationally simple, this method requires precise timing synchronization. Furthermore, its accuracy depends on pilot density, potentially increasing system overhead. Our proposed integer multiple frequency offset estimation uses an algorithm combining pilot-autocorrelation and cross-correlation. This method is robust to timing deviations, and the pilots used in the calculation can be directly derived from the comb pilots inserted symbol by symbol in the channel estimation, requiring no additional design or overhead, while offering superior performance. Moreover, it operates in the frequency domain, requiring only one FFT transform, significantly reducing complexity compared to traditional methods (which require two FFTs).

[0051] Comb pilot design provides a high signal-to-noise ratio input signal for integer multiple frequency offset estimation through pilot subcarriers with uniform frequency domain distribution, significantly improving the reliability of autocorrelation processing.

[0052] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0053] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0054] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0055] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0056] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0057] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0058] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for designing a frequency-domain ZC sequence synchronization header resistant to ultra-large frequency differences, characterized in that, The method includes: The fractional frequency offset is estimated using the training sequence; fractional frequency offset compensation is performed on the received signal; the ZC sequence position is extracted from the compensated signal, the ZC sequence is extracted and correlated with the locally known reference ZC sequence; the peak position is determined from the correlation processing result as the time synchronization position; The complete signal frame is captured using the time synchronization position and a fast Fourier transform is performed. In the transformed data, the pilot subcarrier positions are extracted, and the cross-correlation between the pilot and the local pilot is calculated. Based on the cross-correlation results, autocorrelation processing is performed, including dividing the cross-correlation signal into two continuous subsequences and performing conjugate multiplication and summation. The position of the maximum value is determined from the summation result as the integer multiple frequency offset estimate.

2. The frequency domain ZC sequence synchronization header design method for resisting ultra-large frequency differences as described in claim 1, characterized in that, The fractional frequency offset estimation specifically includes the following steps: Segment the training sequence; For each training sequence, perform an iterative search to estimate the fractional octave frequency offset.

3. The frequency domain ZC sequence synchronization header design method for resisting ultra-large frequency differences as described in claim 1, characterized in that, The ZC sequence includes a sideband protection design, wherein the sideband portions are located on both sides of the ZC base sequence.

4. The frequency domain ZC sequence synchronization header design method for resisting ultra-large frequency differences as described in claim 3, characterized in that, The ZC base sequence is repeated 1 time.

5. The frequency domain ZC sequence synchronization header design method for resisting ultra-large frequency differences as described in claim 1, characterized in that, The pilots are comb pilots designed for channel estimation.

6. The frequency domain ZC sequence synchronization header design method for resisting ultra-large frequency differences as described in claim 1, characterized in that, The relevant processing specifically includes the following steps: Calculate the cross-correlation between the ZC sequence and the local reference ZC sequence; The peak positions of the cross-correlation results were determined.

7. The frequency domain ZC sequence synchronization header design method for resisting ultra-large frequency differences as described in claim 1, characterized in that, The autocorrelation processing specifically includes the following steps: The cross-correlation signal is divided into two continuous subsequences; Perform conjugate multiplication on the two subsequences; sum the results of the multiplication.

8. The frequency domain ZC sequence synchronization header design method for resisting ultra-large frequency differences as described in claim 1, characterized in that, Before performing fractional-fold frequency offset compensation, the received signal is filtered to reduce the impact of noise.

9. The method for designing a frequency-domain ZC sequence synchronization header resistant to ultra-large frequency differences as described in claim 1, characterized in that, The sideband protection design enables the sideband portion to form a continuous sequence structure with the ZC base sequence portion.

10. The frequency domain ZC sequence synchronization header design method for resisting ultra-large frequency differences as described in claim 5, characterized in that, The distribution density of the comb pilot signals is associated with the subsequence partitioning parameters in the autocorrelation processing.

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