Sampling frequency offset tracking method and device, computer device and storage medium

Abstract

The application relates to a sampling frequency offset tracking method and device, computer equipment and a storage medium, which comprises the following steps: performing signal synchronization processing according to the frame structure of a received signal to obtain a frame starting point; performing preliminary sampling frequency offset compensation and channel estimation according to a preamble symbol to obtain a preamble channel estimation result; performing decision feedback channel estimation according to a data symbol to obtain a decision feedback signal estimation result; performing correlation operation on time domain channel response signal sampling points corresponding to effective peak positions to obtain a correlation value; calculating a residual sampling frequency offset according to the correlation value, updating a sampling frequency offset estimation value in combination with a filter coefficient, performing iterative sampling frequency offset compensation according to the updated sampling frequency offset estimation value, and tracking the sampling frequency offset in real time. The application generates channel estimation values based on a preamble symbol and a data symbol respectively, realizes real-time tracking of the sampling frequency offset symbol by symbol, and realizes real-time tracking without a pilot.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a sampling frequency offset tracking method, apparatus, computer device, and storage medium. Background Technology

[0002] Orthogonal Frequency Division Multiplexing (OFDM) technology has been widely used in wireless communication systems such as Starlink broadband communication, 4G / 5G communication, and WiFi 6. Its core idea is to decompose a high-speed bitstream into multiple low-speed sub-bitstreams, which are then modulated onto mutually orthogonal subcarriers for transmission, effectively resisting inter-symbol interference (ISI). However, OFDM systems are extremely sensitive to frequency offset. Sampling Frequency Offset (SFO), as the main type of frequency offset, is caused by clock mismatch between the transmitter and receiver. It destroys the orthogonality of the subcarriers, causing data errors to accumulate with the number of carriers, severely impacting communication performance.

[0003] Existing Sampled Frequency Offset (SFOE) methods primarily rely on preambles and pilots. Preambles are used for initial coarse estimation, while pilots are distributed throughout the data payload to track residual frequency offsets. However, some communication systems (such as the HomePlug AV2 standard) do not include pilots in their OFDM frames, making real-time tracking of residual frequency offsets impossible. Even with pilots, it is difficult to suppress the impact of multipath effects and noise on estimation accuracy. Furthermore, SFO estimation methods based on cyclic prefixes are limited by prefix length and channel reflection, resulting in limited performance improvements.

[0004] Therefore, there is an urgent need for a technical solution that does not rely on pilot signals, can effectively suppress multipath and noise interference, and can track sampling frequency offset in real time, in order to overcome the shortcomings of existing methods. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a sampling frequency offset tracking method, apparatus, computer equipment, and storage medium suitable for synchronization optimization of orthogonal frequency division multiplexing (OFDM) systems. This method and apparatus do not rely on pilot signals, effectively suppress multipath and noise interference, and can track sampling frequency offsets in real time. The specific solution is as follows:

[0006] In a first aspect, embodiments of this application provide a sampling frequency offset tracking method, including:

[0007] Signal synchronization processing is performed based on the frame structure of the received signal to obtain the frame start point; wherein, the received signal includes short training sequence symbols, preamble symbols, and data symbols;

[0008] Preliminary sampling frequency offset compensation and channel estimation are performed based on the preamble symbols to obtain the preamble channel estimation result;

[0009] Based on the data symbols, a decision feedback channel estimation is performed to obtain the decision feedback signal estimation result;

[0010] Based on the preamble channel estimation result and the decision feedback signal estimation result, obtain the first time-domain channel response signal and the second time-domain channel response signal;

[0011] The effective peak positions of the first time-domain channel response signal and the second time-domain channel response signal are determined, and correlation operations are performed based on the sampling points of the time-domain channel response signal corresponding to the effective peak positions to obtain correlation values; wherein, the effective peak positions are the first peak position and the second peak position when the position error between the first peak position and the second peak position is less than a preset threshold, the first peak position is the peak position of the first time-domain channel response signal, and the second peak position is the peak position of the second time-domain channel response signal;

[0012] The residual sampling frequency offset is calculated based on the relevant value, and the estimated sampling frequency offset is updated by combining the filter coefficients. Iterative sampling frequency offset compensation is then performed based on the updated estimated sampling frequency offset to track the sampling frequency offset in real time.

[0013] In one embodiment, the step of performing signal synchronization processing based on the frame structure of the received signal to obtain the frame start point includes:

[0014] Acquire received signals;

[0015] The frame start point is obtained by performing signal synchronization processing based on the short training sequence symbols and preamble symbols of the received signal.

[0016] In one embodiment, the step of performing preliminary sampling frequency offset compensation and channel estimation based on the preamble symbol to obtain the preamble channel estimation result includes:

[0017] The preamble symbol is subjected to time-frequency domain transformation to obtain the frequency domain data of the preamble symbol;

[0018] Correlation operations are performed based on the frequency domain data of the preamble symbol and the reference symbol to obtain the preamble channel estimation result;

[0019] A preliminary sampling frequency offset estimate is generated based on the preamble channel estimation result, and preliminary sampling frequency offset compensation is performed based on the preliminary sampling frequency offset estimate.

[0020] In one embodiment, the step of performing channel estimation based on the data symbols to obtain the decision feedback signal estimation result includes:

[0021] The data symbols are subjected to time-frequency domain transformation to obtain the first frequency domain data of the synchronized data symbols;

[0022] The first frequency domain data is sequentially subjected to equalization processing, demapping processing, and decoding processing;

[0023] If the decoding is correct, the decoding result is re-encoded and mapped to obtain the second frequency domain data of the mapped data symbols.

[0024] Based on the second frequency domain data and the first frequency domain data, correlation calculations are performed to obtain the decision feedback channel estimation result.

[0025] In one embodiment, obtaining the first time-domain channel response signal and the second time-domain channel response signal based on the preamble channel estimation result and the decision feedback signal estimation result includes:

[0026] Perform an inverse fast Fourier transform on the preamble channel estimation result to obtain the first time-domain channel response signal;

[0027] Perform an inverse fast Fourier transform on the decision feedback channel estimation result to obtain the second time-domain channel response signal.

[0028] In one embodiment, the correlation operation based on the time-domain channel response signal sampling points corresponding to the effective peak position to obtain the correlation value includes:

[0029]

[0030] in, For relevant values, The first time-domain channel response signal at the effective peak position sampling points, The second time-domain channel response signal at the effective peak position The conjugate of the sampling points.

[0031] In one embodiment, calculating the residual sampling frequency offset based on the correlation value and updating the estimated sampling frequency offset value in combination with the filter coefficients includes:

[0032]

[0033]

[0034] in, For residual sampling frequency offset, The phase of the correlation value, The signal sampling frequency, The length of the preamble symbol. This is the updated estimated sampling frequency offset value. This is a preliminary estimate of the sampling frequency offset. These are the filter coefficients. .

[0035] Secondly, embodiments of this application provide a sampling frequency offset tracking device, comprising:

[0036] The synchronization module is used to perform signal synchronization processing according to the frame structure of the received signal to obtain the frame start point; wherein, the received signal includes short training sequence symbols, preamble symbols and data symbols;

[0037] The first channel estimation module is used to perform preliminary sampling frequency offset compensation and channel estimation based on the preamble symbol to obtain the preamble channel estimation result.

[0038] The second channel estimation module is used to perform decision feedback channel estimation based on the data symbols to obtain the decision feedback signal estimation result.

[0039] The time-frequency domain conversion module is used to obtain the first time-domain channel response signal and the second time-domain channel response signal based on the preamble channel estimation result and the decision feedback signal estimation result;

[0040] Peak processing module: used to determine the effective peak positions of the first time-domain channel response signal and the second time-domain channel response signal, and to perform correlation calculations based on the sampling points of the time-domain channel response signal corresponding to the effective peak positions to obtain correlation values; wherein, the effective peak positions are the first peak position and the second peak position when the position error between the first peak position and the second peak position is less than a preset threshold, the first peak position is the peak position of the first time-domain channel response signal, and the second peak position is the peak position of the second time-domain channel response signal;

[0041] The sampling frequency offset tracking module is used to calculate the residual sampling frequency offset based on the correlation value, update the estimated sampling frequency offset value in combination with the filter coefficients, and perform iterative sampling frequency offset compensation based on the updated estimated sampling frequency offset value in order to track the sampling frequency offset in real time.

[0042] Thirdly, embodiments of this application provide a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the sampling frequency offset tracking method described in the first aspect.

[0043] Fourthly, embodiments of this application also provide a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the sampling frequency offset tracking method described in the first aspect.

[0044] In summary, this embodiment provides a sampling frequency offset tracking method, apparatus, computer device, and storage medium, including: performing signal synchronization processing based on the frame structure of the received signal to obtain the frame start point; performing preliminary sampling frequency offset compensation and channel estimation based on the preamble symbols to obtain the preamble channel estimation result; performing decision feedback channel estimation based on the data symbols to obtain the decision feedback signal estimation result; performing correlation operations based on the sampling points of the time-domain channel response signal corresponding to the effective peak position to obtain the correlation value; calculating the residual sampling frequency offset based on the correlation value, updating the sampling frequency offset estimate value in combination with the filter coefficients, and performing iterative sampling frequency offset compensation based on the updated sampling frequency offset estimate value to track the sampling frequency offset in real time. This application achieves symbol-by-symbol real-time tracking of the sampling frequency offset by generating channel estimation values ​​based on the preamble symbols and data symbols respectively, achieving real-time tracking without pilot signals. Attached Figure Description

[0045] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 A schematic flowchart of a sampling frequency offset tracking method provided in an embodiment of this application;

[0047] Figure 2 This is a schematic diagram of a data frame structure for a received signal provided in an embodiment of this application;

[0048] Figure 3 This is a flowchart illustrating the steps of channel estimation based on preamble symbols in an embodiment of this application.

[0049] Figure 4 This is a flowchart illustrating the steps of making a decision feedback channel estimation based on data symbols according to an embodiment of this application;

[0050] Figure 5 A schematic diagram illustrating the operational logic of the sampling frequency offset tracking method provided in this application embodiment within an OFDM system;

[0051] Figure 6 This is a structural block diagram of the sampling frequency offset tracking device provided in the embodiments of this application;

[0052] Figure 7 This is a structural block diagram of a computer device provided in an embodiment of this application. Detailed Implementation

[0053] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0054] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0055] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0056] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The drawings only show the components related to this disclosure and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0057] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that these aspects can be practiced without these specific details.

[0058] Please see Figure 1 This paper presents a sampling frequency offset tracking method, applicable to the receiver end of an OFDM wireless communication system, for real-time tracking and compensation of sampling frequency offset. The method is described in detail below with reference to the accompanying drawings and specific steps. The sampling frequency offset tracking method includes the following steps:

[0059] Step 101: Perform signal synchronization processing based on the frame structure of the received signal to obtain the frame start point; wherein, the received signal includes short training sequence symbols, preamble symbols and data symbols.

[0060] In this embodiment, signal synchronization processing is performed based on the frame structure of the received signal to obtain the frame start point, including: acquiring the received signal; and performing signal synchronization processing based on the short training sequence symbols and preamble symbols of the received signal to obtain the frame start point.

[0061] Specifically, during the acquisition of the received signal, the received signal is passed through the radio frequency channel to complete signal down-conversion and filtering. Then, the received analog signal is converted into a digital signal by the AD analog-to-digital converter chip before entering the synchronization processing stage.

[0062] The frame structure of the received signal is as follows Figure 2 As shown, the channel consists of three parts: short training sequence symbols, preamble symbols, and data symbols. The short training sequence symbols are used for automatic gain control (AGC) adjustments and coarse synchronization timing, initially determining the approximate range of the frame. The preamble symbols are used for fine synchronization, further calibrating the frame start position and providing a foundation for subsequent preliminary channel estimation and sampling frequency offset estimation. The data symbols carry the actual transmitted service data and are the core object for subsequent decision feedback channel estimation.

[0063] It is worth noting that the specific methods for performing RF down-conversion and analog-to-digital conversion on the received signal can be selected according to the needs of the actual application scenario, using appropriate down-conversion devices and analog-to-digital conversion devices. No restrictions are imposed here.

[0064] In practical applications, the synchronization process involves first utilizing the periodicity of short training sequence symbols to perform automatic gain control adjustments and coarse synchronization, initially pinpointing the approximate location of the frame. Then, based on the known structural features of the preamble symbols, fine synchronization operations are performed to accurately determine the frame start point, providing a precise time reference for subsequent signal processing.

[0065] Based on the above scheme, short training sequence symbols are used to achieve automatic gain control adjustment and coarse synchronization timing, while preamble symbols are used to achieve fine synchronization. The two work together to accurately locate the frame start point.

[0066] Step 102: Perform preliminary sampling frequency offset compensation and channel estimation based on the preamble symbol to obtain the preamble channel estimation result.

[0067] Specifically, such as Figure 3 As shown, step 102 in this embodiment specifically includes the following sub-steps:

[0068] Step 1021: Perform time-frequency domain transformation on the preamble symbol to obtain the frequency domain data of the preamble symbol.

[0069] Specifically, the preamble symbols extracted after synchronization undergo time-frequency domain transformation processing. This can be achieved using a Fast Fourier Transform (FFT) to convert the time-domain preamble symbols into frequency-domain data. The calculation of the frequency-domain data of the preamble symbols is shown in the following formula:

[0070]

[0071] in, The leading symbol is retrieved after synchronization. For the time-domain sampling points of the leading symbol, The length of the leading symbol. This is the result after the Fourier transform. These are the frequency domain sampling points for the preamble symbol.

[0072] Step 1022: Perform correlation calculations based on the frequency domain data of the preamble symbol and the reference symbol to obtain the preamble channel estimation result.

[0073] Specifically, the reference preamble symbol is a standard preamble frequency domain symbol known at the transmitter. The correlation operation is implemented by multiplying the frequency domain data by the conjugate of the reference symbol, as shown in the following formula:

[0074]

[0075] in, The result is the preamble channel estimation. For the conjugate of the reference preamble symbol.

[0076] Step 1023: Generate a preliminary sampling frequency offset estimate based on the preamble channel estimation result, and perform preliminary sampling frequency offset compensation based on the preliminary sampling frequency offset estimate.

[0077] Specifically, based on the phase information of the preamble channel estimation result, a preliminary sampling frequency offset estimate is generated. Since the sampling frequency offset will cause a fixed phase shift in the channel estimation result, a preliminary sampling frequency offset estimate can be calculated by extracting this phase shift and combining it with the preamble symbol length.

[0078] Subsequently, based on the preliminary sampling frequency offset estimate... Preliminary frequency offset compensation of the received signal can reduce the impact of sampling frequency offset on subsequent signal processing.

[0079] Step 103: Estimate the decision feedback channel based on the data symbols to obtain the decision feedback signal estimation result.

[0080] In this embodiment, as Figure 4 and Figure 5As shown, this step is based on data symbols and generates high-precision channel estimation results through a decision feedback mechanism. Specifically, it includes the following sub-steps:

[0081] Step 1031: Perform time-frequency domain transformation on the data symbols to obtain the first frequency domain data of the synchronized data symbols.

[0082] Specifically, the synchronized data symbols are subjected to FFT time-frequency domain transformation to obtain the first frequency domain data of the data symbols. The calculation formula is as follows:

[0083]

[0084]

[0085]

[0086] in, The length of the cyclic prefix. The first frequency domain data of the data symbol, These are the time-domain sampling points for the synchronized data symbols.

[0087] Step 1032: Perform equalization, demapping and decoding processes on the first frequency domain data in sequence.

[0088] In this embodiment, as Figure 5 As shown, the preamble channel estimation result obtained according to the aforementioned steps For the first frequency domain data Equalization processing is performed to eliminate the effects of channel fading and inter-symbol interference.

[0089] Subsequently, demapping processing is performed based on the modulation scheme of the transmitting end, converting the frequency domain symbols into a binary bit stream. Specifically, modulation schemes such as QPSK and 16QAM can be used. Finally, decoding processing is performed based on the encoding scheme of the transmitting end to recover the original transmitted information. Encoding schemes such as convolutional coding and LDPC coding are also used.

[0090] Step 1033: If the decoding is correct, re-encode and re-map the decoding result to obtain the second frequency domain data of the mapped data symbols.

[0091] Specifically, the decoding result is verified to determine whether the decoding is correct, which can be achieved through methods such as CRC check. If the decoding is incorrect, it indicates that the current signal quality is poor, and the current decision feedback channel estimation result is discarded, maintaining the previous estimation value; if the decoding is correct, the process proceeds to the next step.

[0092] The correct decoding result is re-encoded according to the encoding method of the transmitting end, and then constellation mapping is performed according to the modulation method of the transmitting end to obtain the second frequency domain data of the mapped data symbols. .

[0093] Step 1034: Perform correlation calculations based on the second frequency domain data and the first frequency domain data to obtain the decision feedback channel estimation result.

[0094] Specifically, the formula for calculating the decision feedback channel estimation result is as follows:

[0095]

[0096] in, The first frequency domain data of the data symbol, For second frequency domain data conjugate, This is the result of the decision feedback channel estimation.

[0097] Based on the above scheme, since the second frequency domain data is reconstructed based on the correct decoding results, the decision feedback channel estimation results have higher accuracy.

[0098] Step 104: Based on the preamble channel estimation result and the decision feedback signal estimation result, obtain the first time-domain channel response signal and the second time-domain channel response signal.

[0099] Specifically, in order to extract the time-domain impulse response characteristics of the channel, it is necessary to convert the frequency-domain channel estimation results into a time-domain signal. The specific process is as follows:

[0100] Preamble channel estimation results Performing an inverse fast Fourier transform (IFFT) converts the frequency-domain channel estimate into a time-domain channel response signal, yielding the first time-domain channel response signal. The specific formula is as follows:

[0101]

[0102]

[0103]

[0104] Estimation results of the decision feedback channel Perform an inverse fast Fourier transform (IFFT) to obtain the second time-domain channel response signal. The specific formula is as follows:

[0105]

[0106]

[0107]

[0108] In this embodiment, the time-domain channel response signal can intuitively reflect the multipath characteristics of the channel, and its peak position corresponds to the main multipath components of the channel, providing a basis for subsequent peak processing.

[0109] Step 105: Determine the effective peak positions of the first time-domain channel response signal and the second time-domain channel response signal, and perform correlation calculations based on the sampling points of the time-domain channel response signal corresponding to the effective peak positions to obtain the correlation values.

[0110] The effective peak position is the first peak position and the second peak position when the position error between the first peak position and the second peak position is less than a preset threshold. The first peak position is the peak position of the first time-domain channel response signal, and the second peak position is the peak position of the second time-domain channel response signal.

[0111] Specifically, this step extracts valid channel information through peak filtering and related calculations, providing a basis for calculating residual sampling frequency offset. The preset threshold is preferably ±3 sampling points; that is, when the positional error between the first peak position and the second peak position is within ±3 sampling points, it is determined to be a valid peak position; if it exceeds this range, the current peak is discarded and does not participate in subsequent related calculations. It should be noted that the preset threshold can also be configured according to the needs of the actual application scenario.

[0112] In this embodiment, the first time-domain channel response signal Second time-domain channel response signal Modulus calculations were performed separately to obtain their respective power distributions. Then, a peak search was performed to find the peak position with the highest power, which was denoted as the first peak position. (Corresponding to the first time-domain channel response signal) and the second peak position (Corresponding to the second time-domain channel response signal).

[0113] Determine the position of the first peak With the second peak position The positional error between the sampling points is considered. A preset positional error threshold is ±3 sampling points. If the positional error is within this threshold, it is determined to be a valid peak position; if it exceeds this threshold, the current peak is discarded, and the process returns to the previous step to re-search for peaks (or the current estimation is discarded). This embodiment, through its peak position determination design, can effectively eliminate invalid peaks caused by multipath interference, improving the accuracy of subsequent estimations.

[0114] Based on the effective peak position, extract the corresponding time-domain channel response signal sampling points: the first time-domain channel response signal in sampling points at the location and the second time-domain channel response signal in sampling points at the location .

[0115] Subsequently, the sampling points of the second time-domain channel response signal are conjugately calculated, and then multiplied with the sampling points of the first time-domain channel response signal to obtain the correlation value. The calculation is shown in the following formula:

[0116]

[0117] in, For relevant values, The first time-domain channel response signal at the effective peak position sampling points, The second time-domain channel response signal at the effective peak position The conjugate of the sampling points.

[0118] Step 106: Calculate the residual sampling frequency offset based on the relevant values, update the estimated sampling frequency offset value by combining the filter coefficients, and perform iterative sampling frequency offset compensation based on the updated estimated sampling frequency offset value to track the sampling frequency offset in real time.

[0119] In this embodiment, this step calculates the residual sampling frequency offset based on the correlation value, and achieves real-time tracking of the sampling frequency offset through iterative updates.

[0120] According to relevant values Phase information, calculate residual sampling frequency offset The phase of the correlation value is caused by the residual sampling frequency offset. Combining the signal sampling frequency, the effective peak position difference, and the preamble symbol length, the residual sampling frequency offset can be calculated using the following formula:

[0121]

[0122]

[0123] in, For residual sampling frequency offset, The phase of the correlation value, The signal sampling frequency, The length of the preamble symbol.

[0124] Combined with filter coefficients ( Update the sampling frequency offset estimate. Filter coefficients. The estimation accuracy and convergence speed for balancing residual sampling frequency offset can be adaptively adjusted according to the actual channel environment, and the update formula is shown below:

[0125]

[0126] in, This is the updated estimated sampling frequency offset value. This is a preliminary estimate of the sampling frequency offset. These are the filter coefficients. , This represents the residual sampling frequency offset. The filter coefficients are... k It can be adaptively adjusted according to the channel characteristics of the actual communication scenario to balance estimation accuracy and convergence speed.

[0127] In this embodiment, based on the updated sampling frequency offset estimate Iterative sampling and frequency offset compensation are performed on the received signal; simultaneously, As the initial sampling frequency offset estimate for the next iteration By repeating steps 102 to 106 above, symbol-by-symbol real-time tracking of sampling frequency offset can be achieved.

[0128] Based on the above scheme, a sampling frequency offset tracking method is provided, which can track in real time without pilots. Through a decision feedback mechanism, a channel estimate is generated based on each data symbol to achieve symbol-by-symbol real-time tracking of the sampling frequency offset. It does not rely on pilots and is adapted to OFDM systems without pilots, solving the defect of existing methods that cannot track in real time without pilots. Through time-domain peak filtering, only valid estimates with peak position errors within a preset threshold range are retained, eliminating invalid estimates caused by multipath interference. At the same time, the channel impulse response characteristics are utilized to suppress the influence of random noise on the estimation results, significantly improving the estimation accuracy in complex channel environments. Through the dual-channel estimation linkage of preamble and data symbols, combined with conjugate correlation operation and iterative compensation mechanism, residual sampling frequency offset is effectively reduced, the sampling frequency offset estimate is continuously optimized, and the system synchronization performance and data transmission reliability are improved.

[0129] In a more detailed embodiment, the specific technical solution of the sampling frequency offset tracking method provided in this embodiment is as follows:

[0130] Synchronization processing involves receiving signals that have undergone radio frequency downconversion and analog-to-digital conversion. Automatic gain control and coarse synchronization are achieved through short training sequences to determine the frame start point; fine synchronization is achieved through preamble symbols.

[0131] Initial frequency offset compensation involves making preliminary frequency offset adjustments to the received signal based on a preset initial estimate.

[0132] The time-frequency domain transformation involves performing an FFT transform on the synchronized preamble and data symbols respectively, converting them into frequency domain symbols.

[0133] Dual-channel estimation is performed: preamble channel estimation, which uses the conjugate of the preamble symbol frequency domain data and the reference preamble symbol for correlation operation to obtain the preamble channel estimation result; and decision feedback channel estimation, which uses the data symbol frequency domain data after equalization, demapping and decoding. If the decoding is correct, it is re-encoded and mapped, and then the mapping data is correlated with the conjugate of the original data symbol frequency domain data to obtain the decision feedback channel estimation result.

[0134] Time-domain transformation and peak processing: IFFT transformation is performed on the two channel estimates to obtain the time-domain response signal. The modulus is calculated and the peak is searched. Only valid estimates with peak position errors less than or equal to 3 sampling points are retained.

[0135] Correlation and frequency offset calculations are performed by extracting time-domain sampling points based on the effective peak positions and performing conjugate correlation operations, and using the correlation value phase to calculate the residual sampling frequency offset.

[0136] Iterative tracking compensation is performed, and the estimated sampling frequency offset is updated by combining the filter coefficients and fed back to the initial compensation step for iterative optimization.

[0137] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0138] Based on the same inventive concept, this application also provides a sampling frequency offset tracking device for implementing the sampling frequency offset tracking method described above. The solution provided by this device is similar to the implementation scheme described in the above method; therefore, the specific limitations in one or more sampling frequency offset tracking device embodiments provided below can be found in the limitations of the sampling frequency offset tracking method described above, and will not be repeated here.

[0139] In one embodiment, such as Figure 6 As shown, a sampling frequency offset tracking device 600 is provided, including: a synchronization module 610, a first channel estimation module 620, a second channel estimation module 630, a time-frequency domain conversion module 640, a peak processing module 650, and a sampling frequency offset tracking module 660, wherein:

[0140] The synchronization module 610 is used to perform signal synchronization processing based on the frame structure of the received signal to obtain the frame start point; wherein the received signal includes short training sequence symbols, preamble symbols, and data symbols. Specifically, the synchronization module achieves automatic gain control and coarse synchronization through short training sequence symbols, and achieves fine synchronization through preamble symbols to accurately locate the frame start point.

[0141] The first channel estimation module 620 is used to perform preliminary sampling frequency offset compensation and channel estimation based on the preamble symbols to obtain the preamble channel estimation result. Specifically, the first channel estimation module includes a preamble FFT unit, a preamble correlation operation unit, and a preliminary frequency offset compensation unit, which are used to implement the time-frequency domain transformation of the preamble symbols, the correlation operation with the reference symbols, and the preliminary sampling frequency offset compensation, respectively.

[0142] The second channel estimation module 630 is used to perform decision feedback channel estimation based on the data symbols to obtain the decision feedback signal estimation result. Specifically, the second channel estimation module includes a data FFT unit, an equalization demapping decoding unit, an encoding mapping unit, and a decision feedback correlation operation unit, which are respectively used to implement the time-frequency domain transformation of the data symbols, equalization demapping decoding, re-encoding mapping of the correct decoding result, and decision feedback correlation operation.

[0143] The time-frequency domain conversion module 640 is used to obtain a first time-domain channel response signal and a second time-domain channel response signal based on the preamble channel estimation result and the decision feedback signal estimation result. Specifically, the time-frequency domain conversion module includes two IFFT units, which perform inverse fast Fourier transform on the preamble channel estimation result and the decision feedback channel estimation result, respectively, and output the corresponding time-domain channel response signals.

[0144] The peak processing module 650 is used to determine the effective peak positions of the first time-domain channel response signal and the second time-domain channel response signal, and to perform correlation operations based on the sampling points of the time-domain channel response signal corresponding to the effective peak positions to obtain correlation values. The effective peak positions are the first peak position and the second peak position when the positional error between the first peak position and the second peak position is less than a preset threshold. The first peak position is the peak position of the first time-domain channel response signal, and the second peak position is the peak position of the second time-domain channel response signal. Specifically, the peak processing module includes a modulus calculation unit, a peak search unit, a peak judgment unit, and a correlation operation unit, which are respectively used to perform modulus calculation, peak search, peak validity judgment, and conjugate correlation operations on the effective sampling points of the time-domain channel response signal.

[0145] The sampling frequency offset tracking module 660 is used to calculate the residual sampling frequency offset based on the correlation value, update the estimated sampling frequency offset value in combination with the filter coefficients, and perform iterative sampling frequency offset compensation based on the updated estimated sampling frequency offset value to track the sampling frequency offset in real time. Specifically, the sampling frequency offset tracking module includes a residual frequency offset calculation unit, a frequency offset estimation update unit, and an iterative compensation unit, which are used to calculate the residual sampling frequency offset, update the estimated sampling frequency offset value, and perform iterative frequency offset compensation, respectively.

[0146] The sampling frequency offset tracking device provided in this embodiment corresponds one-to-one with the sampling frequency offset tracking method in Embodiment 1 above. The specific functions of each module can be found in the detailed description of Embodiment 1, and will not be repeated here. This device can be integrated into the receiver of an OFDM system and implemented through hardware circuits, software programs, or a combination of hardware and software.

[0147] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 7 As shown, the computer device includes a processor, memory, input / output interfaces, a communication interface, a display unit, and an input device. The processor, memory, and input / output interfaces are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The input / output interfaces are used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a sampling frequency offset tracking method. The display unit is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0148] Those skilled in the art will understand that Figure 7 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0149] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the aforementioned method embodiment.

[0150] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the aforementioned method embodiments.

[0151] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the foregoing method embodiments.

[0152] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0153] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0154] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A sampling frequency offset tracking method, characterized in that, include: Signal synchronization processing is performed based on the frame structure of the received signal to obtain the frame start point; wherein, the received signal includes short training sequence symbols, preamble symbols, and data symbols; Preliminary sampling frequency offset compensation and channel estimation are performed based on the preamble symbols to obtain the preamble channel estimation result; Based on the data symbols, a decision feedback channel estimation is performed to obtain the decision feedback channel estimation result; Based on the preamble channel estimation result and the decision feedback channel estimation result, obtain the first time-domain channel response signal and the second time-domain channel response signal; The effective peak positions of the first time-domain channel response signal and the second time-domain channel response signal are determined, and correlation operations are performed based on the sampling points of the time-domain channel response signal corresponding to the effective peak positions to obtain correlation values; wherein, the effective peak positions are the first peak position and the second peak position when the positional error between the first peak position and the second peak position is within the range of a preset threshold, the first peak position is the peak position of the first time-domain channel response signal, and the second peak position is the peak position of the second time-domain channel response signal; the preset threshold is ±3 sampling points; The residual sampling frequency offset is calculated based on the relevant values, and the estimated sampling frequency offset is updated by combining the filter coefficients. Iterative sampling frequency offset compensation is then performed based on the updated estimated sampling frequency offset to track the sampling frequency offset in real time. The step of obtaining the first time-domain channel response signal and the second time-domain channel response signal based on the preamble channel estimation result and the decision feedback channel estimation result includes: Perform an inverse fast Fourier transform on the preamble channel estimation result to obtain the first time-domain channel response signal; Perform an inverse fast Fourier transform on the decision feedback channel estimation result to obtain the second time-domain channel response signal.

2. The method according to claim 1, characterized in that, The step of performing signal synchronization processing based on the frame structure of the received signal to obtain the frame start point includes: Acquire received signals; The frame start point is obtained by performing signal synchronization processing based on the short training sequence symbols and preamble symbols of the received signal.

3. The method according to claim 1, characterized in that, The step of performing preliminary sampling frequency offset compensation and channel estimation based on the preamble symbol to obtain the preamble channel estimation result includes: The preamble symbol is subjected to time-frequency domain transformation to obtain the frequency domain data of the preamble symbol; Correlation operations are performed based on the frequency domain data of the preamble symbol and the reference symbol to obtain the preamble channel estimation result; A preliminary sampling frequency offset estimate is generated based on the preamble channel estimation result, and preliminary sampling frequency offset compensation is performed based on the preliminary sampling frequency offset estimate.

4. The method according to claim 1, characterized in that, The process of performing channel estimation based on the data symbols to obtain the decision feedback channel estimation result includes: The data symbols are subjected to time-frequency domain transformation to obtain the first frequency domain data of the synchronized data symbols; The first frequency domain data is sequentially subjected to equalization processing, demapping processing, and decoding processing; If the decoding is correct, the decoding result is re-encoded and mapped to obtain the second frequency domain data of the mapped data symbols. Based on the second frequency domain data and the first frequency domain data, correlation calculations are performed to obtain the decision feedback channel estimation result.

5. The method according to claim 1, characterized in that, The correlation operation based on the time-domain channel response signal sampling points corresponding to the effective peak positions to obtain the correlation values ​​includes: in, For relevant values, The first time-domain channel response signal at the effective peak position sampling points, The second time-domain channel response signal at the effective peak position The conjugate of the sampling points.

6. The method according to claim 5, characterized in that, The residual sampling frequency offset is calculated based on the aforementioned correlation value, and the estimated sampling frequency offset is updated by combining the filter coefficients, including: in, For residual sampling frequency offset, The phase of the correlation value, The signal sampling frequency, The length of the preamble symbol. This is the updated estimated sampling frequency offset value. This is a preliminary estimate of the sampling frequency offset. These are the filter coefficients. .

7. A sampling frequency offset tracking device, characterized in that, include: The synchronization module is used to perform signal synchronization processing according to the frame structure of the received signal to obtain the frame start point; wherein, the received signal includes short training sequence symbols, preamble symbols and data symbols; The first channel estimation module is used to perform preliminary sampling frequency offset compensation and channel estimation based on the preamble symbol to obtain the preamble channel estimation result. The second channel estimation module is used to perform decision feedback channel estimation based on the data symbols and obtain the decision feedback channel estimation result. The time-frequency domain conversion module is used to obtain the first time-domain channel response signal and the second time-domain channel response signal based on the preamble channel estimation result and the decision feedback channel estimation result; A peak processing module is used to determine the effective peak positions of the first time-domain channel response signal and the second time-domain channel response signal, and to perform correlation calculations based on the sampling points of the time-domain channel response signal corresponding to the effective peak positions to obtain correlation values; wherein, the effective peak positions are the first peak position and the second peak position when the positional error between the first peak position and the second peak position is within a preset threshold range, the first peak position is the peak position of the first time-domain channel response signal, and the second peak position is the peak position of the second time-domain channel response signal; the preset threshold is ±3 sampling points; The sampling frequency offset tracking module is used to calculate the residual sampling frequency offset based on the correlation value, update the estimated sampling frequency offset value in combination with the filter coefficients, and perform iterative sampling frequency offset compensation based on the updated estimated sampling frequency offset value in order to track the sampling frequency offset in real time. The time-frequency domain conversion module is further configured to perform an inverse fast Fourier transform on the preamble channel estimation result to obtain the first time-domain channel response signal; and to perform an inverse fast Fourier transform on the decision feedback channel estimation result to obtain the second time-domain channel response signal.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the sampling frequency offset tracking method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the sampling frequency offset tracking method according to any one of claims 1 to 6.

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