A Frequency-Domain Carrier Synchronization Method and Device Based on Sparse Pilot

Abstract

The present application discloses a frequency-domain carrier synchronization method and apparatus based on sparse pilot frequency, which relates to the technical field of carrier frequency synchronization. The method includes: the transmitting end generates a data sequence and an original UW sequence; the transmitting end inserts the original UW sequence into the data sequence in an equally spaced postposition manner to obtain a first data transmission frame, and sends the first data transmission frame to the receiving end; the receiving end detects the received second data transmission frame to determine the maximum peak position of the frequency-domain signal; the receiving end determines a frequency offset estimation value according to the maximum peak position of the frequency-domain signal; the receiving end performs deviation correction on the second data transmission frame based on the frequency offset estimation value to obtain the first data transmission frame. This method comprehensively considers the influencing factors in the actual communication transmission process, and improves the anti-interference performance and the accuracy of frequency offset estimation.

Description

Technical Field

[0001] The present application relates to the technical field of carrier frequency synchronization, and in particular, to a frequency-domain carrier synchronization method and apparatus based on sparse pilot signals. Background Art

[0002] With the rapid development of wireless communication, the demand for data transmission in different satellite systems is increasing continuously, and the integration of wireless communication and mobile communication systems has become more and more common. In the field of wireless communication, the requirements for data transmission rate, stability and reliability are increasing day by day. As a key link to ensure accurate signal transmission, carrier synchronization technology has become increasingly important. At present, burst communication systems are applied in key communication fields such as satellite communication and airborne command emergency communication. When the communication system works in a high-dynamic environment, the Doppler frequency shift generated by the relative movement between the communication parties and the frequency difference of the oscillators at the transceiver end cause a large frequency offset in the system, which has an adverse effect on the communication quality.

[0003] The existing burst communication systems are divided into a feed-forward working mode and a feedback working mode according to the working mode. According to whether pilot assistance is required, they can be divided into data-aided and non-data-aided categories. The feed-forward working mode usually combines with data assistance to complete carrier synchronization, and is generally used for burst communication carrier synchronization. The feedback working mode takes the phase-locked loop as the core and directly extracts the coherent carrier from the received signal, which can make full use of the frequency band resources. However, when there is a large relative speed between the communication parties, the severe Doppler effect will cause a large carrier Doppler frequency shift, and even a large Doppler frequency shift change rate.

[0004] In addition, the traditional method for estimating the frequency offset is realized by multiplying the front and rear pilots pairwise in conjugate and then summing. If there are M pilots in the data segment, after multiplying the front and rear pilots in conjugate and summing, M-1 complex results are obtained, and then the complex results are transformed to calculate M-1 frequency offset values, and then the average value of the frequency offset values is obtained to get the final frequency offset value. However, this traditional method for estimating the frequency offset has the problem of low accuracy. Especially in an environment with low signal-to-noise ratio, the ability to capture the frequency offset is weak, and the frequency offset value cannot be accurately estimated, resulting in the receiving end being unable to correctly identify the synchronization information, and even causing communication interruption, showing poor anti-interference performance and low estimation accuracy. Summary of the Invention

[0005] The embodiments of the present application provide a frequency-domain carrier synchronization method and device based on sparse pilot frequency, which solve the problems of transmission signal distortion or spectrum imbalance in the prior art. By using a data-aided feedforward working mode, the original UW sequence at the transmitting end is correlated with the first UW sequence at the receiving end, and the complex data is obtained through conjugate summation. Then, the time-domain signal is converted into a frequency-domain signal through fast Fourier transform, the position of the power spectrum peak is calculated, and then the frequency offset value is calculated. The problem of poor anti-interference performance of frequency offset estimation is effectively solved, and the accuracy of frequency offset estimation is improved.

[0006] In a first aspect, the embodiments of the present application provide a frequency-domain carrier synchronization method based on sparse pilot frequency, including: the transmitting end generates a data sequence and an original UW sequence; the transmitting end inserts the original UW sequence into the data sequence in an equally spaced postposition manner to obtain a first data transmission frame, and sends the first data transmission frame to the receiving end; the receiving end detects the received second data transmission frame to determine the maximum peak position of the frequency-domain signal; the receiving end determines a frequency offset estimation value according to the maximum peak position of the frequency-domain signal; the receiving end performs deviation correction on the second data transmission frame based on the frequency offset estimation value to obtain the first data transmission frame.

[0007] In a possible implementation manner, after the transmitting end inserts the original UW sequence into the data sequence in an equally spaced postposition manner to obtain a first data transmission frame, the method further includes: performing modulation and noise addition processing on the first data transmission frame; wherein, the modulation and noise addition processing includes: performing double-sideband modulation on the baseband signal in the first data transmission frame to obtain a modulation signal; adding noise to the modulation signal by using an optimized Gaussian channel; wherein, the optimized Gaussian channel includes introducing a multipath fading channel into the Gaussian channel.

[0008] In a possible implementation manner, the receiving end detects the received second data transmission frame to determine the maximum peak position of the frequency-domain signal, including: the receiving end extracts the second data transmission frame to obtain a first UW sequence; performing correlation calculation on the first UW sequence and the original UW sequence to obtain an extraction sequence; determining the maximum peak position of the frequency-domain signal according to the extraction sequence.

[0009] In a possible implementation manner, the performing correlation calculation on the first UW sequence and the original UW sequence to obtain an extraction sequence includes: performing correlation calculation on the first UW sequence and the original UW sequence according to a correlation formula to obtain an extraction sequence; the correlation formula is as follows:

[0010] ;

[0011] In the formula, Denote the correlation value between the received first UW sequence and the original UW sequence, i.e., the extracted sequence. Denote the received first UW sequence. Denote the original UW sequence. Denote taking the conjugate of the original UW sequence. Denote the quantities of the first UW sequence and the original UW sequence.

[0012] In a possible implementation manner, the determining the maximum peak position of the frequency-domain signal according to the extracted sequence includes: Based on the extracted sequence, performing signal conversion using the fast Fourier transform method to determine the position of the maximum value power spectrum of the frequency-domain signal; According to the position of the maximum value power spectrum of the frequency-domain signal, determining the maximum peak position.

[0013] In a possible implementation manner, the based on the extracted sequence, performing signal conversion using the fast Fourier transform method to determine the position of the maximum value power spectrum of the frequency-domain signal includes: Based on the extracted sequence, performing signal conversion using the fast Fourier transform method to determine the power spectrum of the frequency-domain signal; Traversing the power spectrum to determine multiple local peaks; According to the peak screening strategy, determining the maximum value power spectrum and its corresponding frequency-domain index from the multiple local peaks; where the peak screening strategy includes taking the local peak with the highest correlation with the original UW sequence as the maximum value power spectrum; Mapping the frequency-domain index to the frequency axis, taking the position where the frequency corresponding to the maximum value power spectrum is located as the position of the maximum value power spectrum, and according to the position of the maximum value power spectrum, determining the frequency range of the frequency domain; The maximum peak position of the frequency-domain signal is the position of the maximum value power spectrum.

[0014] In a possible implementation manner, the receiving end determining the frequency offset estimation value according to the maximum peak position includes: The receiving end determining the frequency offset estimation value according to the maximum peak position and the frequency offset estimation formula; The frequency offset estimation formula is as follows:

[0015] ;

[0016] In the formula, Denote the frequency offset estimation value. Denote the maximum peak position. Denote the sampling rate. Denote the length of the data block. Denote the number of points of the fast Fourier transform.

[0017] In a second aspect, an embodiment of the present application provides a device for frequency-domain carrier synchronization based on sparse pilot frequency, including: a data acquisition module for generating a data sequence and an original UW sequence at a transmitting end; a data processing module for the transmitting end inserting the original UW sequence into the data sequence in an equally spaced post-insertion manner to obtain a first data transmission frame and sending the first data transmission frame to a receiving end; the receiving end detecting the received second data transmission frame to determine the maximum peak position of a frequency-domain signal; a frequency offset calculation module for the receiving end determining a frequency offset estimation value according to the maximum peak position of the frequency-domain signal; and a carrier synchronization module for the receiving end performing deviation correction on the second data transmission frame based on the frequency offset estimation value to obtain the first data transmission frame.

[0018] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0019] By adopting a method and device for frequency-domain carrier synchronization based on sparse pilot frequency, the embodiments of the present application effectively solve the problems of low estimation accuracy and poor noise immunity in the frequency offset estimation process. Based on the cross-distributed data structure composed of the data sequence and the original UW sequence, conjugate summation is performed on the first UW sequence and the original UW sequence received at the receiving end. The position of the maximum peak is determined by using the fast Fourier transform, and the frequency offset estimation value is determined according to the maximum peak position. Considering the actual signal transmission environment, especially in a low signal-to-noise ratio environment, while simplifying the calculation, the robustness and anti-interference ability of the frequency offset estimation are enhanced, and the accuracy of the frequency offset estimation is improved. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for describing the embodiments of the present application or the prior art. Obviously, the following drawings are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a flowchart of a method for frequency-domain carrier synchronization based on sparse pilot frequency provided by an embodiment of the present application;

[0022] Figure 2 It is a schematic structural diagram of a first data transmission frame provided by an embodiment of the present application;

[0023] Figure 3 It is a result diagram of a frequency offset estimation experiment provided by an embodiment of the present application;

[0024] Figure 4 It is a result diagram of a traditional frequency offset estimation experiment provided by an embodiment of the present application;

[0025] Figure 5 This is a schematic structural diagram of a frequency-domain carrier synchronization device based on sparse pilot frequency provided by an embodiment of the present application.

[0026] In the accompanying drawings, the modules represented by a frequency-domain carrier synchronization device 500 based on sparse pilot frequency are described as follows:

[0027] Data acquisition module 501, data processing module 502, frequency offset calculation module 503, carrier synchronization module 504. Specific implementation manners

[0028] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0029] The following explanations are made for some technologies involved in the embodiments of the present application to facilitate understanding. It should be considered that they are only exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described here without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, the descriptions of some well-known functions and structures are omitted in the following.

[0030] Figure 1 This is a flowchart of a frequency-domain carrier synchronization method based on sparse pilot frequency provided by an embodiment of the present application, including steps 101 to 105. Figure 1 This is only an execution order shown in the embodiment of the present application and does not represent the only execution order of the frequency-domain carrier synchronization method based on sparse pilot frequency. When the final result can be achieved, Figure 1 the steps shown can be executed in parallel or reversed, as follows.

[0031] Step 101: The transmitting end generates a data sequence and an original UW sequence.

[0032] In the embodiment of the present application, since the original UW sequence has a unique pattern and good autocorrelation, the receiving end of data transmission can more easily identify the original UW sequence, thereby more accurately achieving frame synchronization and timing recovery, and significantly improving the accuracy of carrier synchronization. Therefore, the original UW sequence is used as the pilot sequence. In addition, the original UW sequence has a short length and high spectral efficiency. Combining the data sequence with the original UW sequence can support various communication scenarios and transmission requirements without increasing additional spectral overhead, and achieve efficient synchronization and data transmission.

[0033] Step 102: The transmitting end inserts the original UW sequence into the data sequence in an equally spaced postposition manner to obtain the first data transmission frame, and sends the first data transmission frame to the receiving end.

[0034] Among them, as Figure 2 shown, at the transmitting end of data transmission, the data sequence of the original bit stream and the original UW sequence are generated. The original UW sequence is inserted into the data sequence in an equally spaced postposition manner, and is composed in a cross-distributed form by data segments to form the first data transmission frame.

[0035] Exemplarily, there is the following first data transmission frame:

[0036] Such as the data sequence,

[0037] Such as the original UW sequence.

[0038] Insert the sequence into the data sequence in an equally spaced postposition manner, and so on. Insert original UW sequences into the data sequence to form the first data block (such as including and , , and ).

[0039] Finally, a total of data blocks are generated, and data blocks constitute the first data transmission frame (such as including

[0040] Compared with the traditional transmitting end transmission frame, the cross-distributed structure provided in the embodiment of the present application ensures the uniform distribution of the original UW sequence, provides a reference point for frequency offset estimation for the entire first data transmission frame. It no longer affects the communication quality due to too low signal-to-noise ratio of a certain data sequence segment, reduces the computational complexity of frequency offset estimation, and reduces the estimation error caused by relying on the time interval of a small number of pilot signals in the prior art.

[0041] After inserting the original UW sequence into the data sequence in an equally spaced postposition manner at the transmitting end to obtain the first data transmission frame, the first data transmission frame can also be subjected to modulation and noise addition processing. Modulation and noise addition can simulate the signal degradation process in a real communication environment and is suitable for performance testing in complex scenarios such as burst communication and satellite communication. Among them, the modulation and noise addition processing includes:

[0042] Perform double-sideband modulation on the baseband signal in the first data transmission frame to obtain a modulated signal; add noise to the modulated signal using an optimized Gaussian channel.

[0043] Among them, optimizing the Gaussian channel includes introducing a multipath fading channel into the Gaussian channel.

[0044] Specifically, in the embodiments of the present application, the original UW sequence is used as the pilot sequence. During the modulation process of the first data transmission frame, the amplitude change of the first UW sequence is converted into the amplitude change of the carrier signal. Since the frequency and phase characteristics of the pilot signal are fixed, it is the same as the first UW sequence received by the receiving end of the data transmission. In addition, due to the influence of the Doppler effect during the data frame transmission process, the carrier frequency may shift. During the transmission process, this frequency shift can be continuously estimated and corrected through frequency offset tracking to ensure carrier synchronization.

[0045] During the signal processing process, a multipath fading channel is added to the Gaussian channel. Compared with the processing of a single Gaussian channel, the optimized Gaussian channel is more general and practical, and can be applied to various data rates, modulation methods, code rates, and channel conditions, such as BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (Sixteen Quadrature Amplitude Modulation), 64QAM (Sixty - four Quadrature Amplitude Modulation), etc.

[0046] Through modulation, the original UW sequence can be transmitted on different frequency bands, avoiding interference between channels and improving the anti - interference ability of the pilot sequence. Existing technologies usually perform noise reduction processing on signals to improve signal quality and the detection ability of targets. However, information distortion or loss may occur during the noise reduction process, increasing the computational complexity and cost. At the same time, noise reduction processing usually needs to be optimized in a specific noise environment and its effect is not good in some dynamic or uncertain noise environments. The present application selects noise addition processing to better simulate the real transmission environment, adds an appropriate amount of noise to the pilot sequence using the stochastic resonance algorithm, improves the detection performance of the first UW sequence, and thus improves the anti - interference ability and frequency offset correction ability of the overall carrier signal.

[0047] Through modulation and noise addition processing, the recovery ability and frequency offset estimation performance of the first UW sequence under different signal - to - noise ratios can be more accurately evaluated, helping to evaluate its anti - interference performance and providing a dynamic optimization scheme for changes in the channel environment.

[0048] Step 103: The receiving end detects the received second data transmission frame and determines the position of the maximum peak of the frequency - domain signal.

[0049] In some possible implementation manners, step 103 may include:

[0050] The receiving end extracts the second data transmission frame to obtain the first UW sequence, performs correlation calculation on the first UW sequence and the original sequence to obtain the extracted sequence. According to the extracted sequence, the position of the maximum peak of the frequency - domain signal is determined.

[0051] Specifically, the receiving end pre-stores a pilot sequence, i.e., the original UW sequence. Both the receiving end and the transmitting end pre-store the pilot sequence, i.e., the original UW sequence. Among them, the second data transmission frame includes the first UW sequence and the received data sequence. The original UW sequence serves as a reference signal known to the receiving end. The first UW sequence and the original UW sequence essentially have the same and fixed frequency and phase. Therefore, the original UW sequence and / or the first UW sequence can provide a reliable carrier synchronization reference. After correlation calculation, subsequent frequency offset estimation is performed. The traditional method of calculating the spectrum usually performs pairwise conjugate multiplication of the front and back samples of the pilot sequence to achieve frequency offset correction. However, due to problems such as rounding errors or overflows that may be introduced by the complex operations of the Fourier transform, the numerical instability is aggravated, thus affecting the accuracy of the results. Therefore, in the embodiments of the present application, only the first UW sequence in the received second transmission frame needs to be extracted, and the conjugate calculation is performed on the first UW sequence and the original UW sequence to obtain a number of correlation values. According to the correlation values, the corresponding two extraction sequences can be determined. Those skilled in the art can extract the first UW sequence from the received signal, i.e., the second transmission frame, according to the known insertion rule of the pilot sequence.

[0052] In some possible implementation manners, determining the maximum peak position of the frequency-domain signal according to the extraction sequence may include:

[0053] Performing correlation calculation on the first UW sequence and the original UW sequence according to the relevant formula to obtain the extraction sequence. The relevant formula is as follows:

[0054] ;

[0055] In the formula, represents the correlation value between the first UW sequence at the receiving end and the original UW sequence, i.e., the extraction sequence, represents the received first UW sequence, represents the original UW sequence, represents taking the conjugate of the original UW sequence, represents the number of the original UW sequences and / or the first UW sequences.

[0056] In some possible implementation manners, determining the maximum peak position of the frequency-domain signal according to the extraction sequence may include steps 1 to 2:

[0057] Step 1: Based on the extraction sequence, use the fast Fourier transform method to perform signal conversion to determine the position of the maximum value power spectrum of the frequency-domain signal.

[0058] In some possible implementation manners, step 1 may include steps 1.1 to 1.5.

[0059] Step 1.1: Based on the extracted sequence, perform signal conversion using the fast Fourier transform method to determine the power spectrum of the frequency-domain signal.

[0060] Specifically, the fast Fourier transform method (FFT) can be used to convert the time-domain signal into a frequency-domain signal, such as by implementing the conversion formula as follows:

[0061] ;

[0062] In the formula, represents the frequency-domain signal, represents the time-domain signal, represents the number of points of the fast Fourier transform, represents the base of the natural logarithm, represents the complex exponential function, represents the imaginary unit, represents the frequency, represents the time.

[0063] Calculate the power spectrum using the complex values of the frequency-domain signal. The power spectrum formula can be obtained by calculating the square of the absolute value of the frequency-domain signal, as follows:

[0064] ;

[0065] In the formula, represents the power spectrum, represents the frequency-domain signal, represents the frequency corresponding amplitude, represents the frequency.

[0066] Step 1.2: Traverse the power spectrum to determine multiple local peaks.

[0067] Step 1.3: According to the peak selection strategy, determine the maximum power spectrum and its corresponding frequency-domain index from multiple local peaks; among them, the peak selection strategy includes taking the local peak with the highest correlation with the original UW sequence as the maximum power spectrum.

[0068] Specifically, after the communication signal undergoes multipath propagation, the signals of different paths will be superimposed in the frequency domain, resulting in multiple peaks on the power spectrum, interfering with the detection of the subsequent maximum peak. In addition, in a low signal-to-noise ratio environment, there may be pseudo-peaks caused by random noise in the power spectrum, interfering with the judgment of the maximum peak. For such pseudo-peaks, that is, local peaks, in this application, through the peak selection strategy, multiple local peaks are screened, and the peak with the highest correlation with the original UW sequence, that is, the peak with a correlation value approaching 1, is selected as the maximum power spectrum, improving the accuracy of subsequent maximum peak positioning.

[0069] Step 1.4: Map the frequency-domain index to the frequency axis. Take the position corresponding to the frequency of the maximum power spectrum as the position of the maximum power spectrum, and determine the frequency range of the frequency domain according to the position of the maximum power spectrum.

[0070] Specifically, during the signal transmission, the frequency-domain position changes, resulting in a shift of the signal spectrum on the frequency axis. The signal received at the receiving end is not completely aligned with the signal of the transmitting end expected to be received, which affects subsequent demodulation and decoding processes. The result of the fast Fourier algorithm is a complex number array, where each element represents the amplitude and phase of the frequency-domain signal at the corresponding frequency. By combining the symmetry and periodicity of the discrete Fourier transform, the frequency-domain signal of the extracted sequence is decomposed into multiple discrete Fourier transforms of smaller scales and combined for solution, thus greatly reducing the computational complexity. According to the position of the frequency corresponding to the maximum power spectrum, determine which half segment it corresponds to in the frequency domain to facilitate subsequent accurate calculation of the frequency offset estimation value.

[0071] Step 1.5: The position of the maximum peak of the frequency-domain signal is the position of the maximum power spectrum.

[0072] Step Two: Determine the position of the maximum peak according to the position of the maximum power spectrum of the frequency-domain signal.

[0073] Step 104: The receiving end determines the frequency offset estimation value according to the position of the maximum peak of the frequency-domain signal.

[0074] Specifically, the receiving end determines the frequency offset estimation value according to the position of the maximum peak and the frequency offset estimation formula. The frequency offset estimation formula is as follows:

[0075] ;

[0076] In the formula, represents the frequency offset estimation value, represents the position of the maximum peak, represents the sampling rate, represents the length of the data block, represents the number of points of the fast Fourier transform.

[0077] Exemplarily, the sampling rate set during the simulation experiment is 30.72e6, and the number of points of the fast Fourier transform set is 512.

[0078] Among them, as Figure 3 shown, it is the result graph of the frequency offset estimation experiment of this application under low signal-to-noise ratio conditions. It can be directly seen from Figure 3 the remaining frequency offset range represented by the abscissa. Compared with Figure 4Compared with the result graph of the traditional frequency offset estimation experiment shown, the remaining frequency offset range of this application is shortened from ±5000 Hz to about ±1000 Hz, and the accuracy of frequency offset estimation is significantly improved. And through the frequency offset estimation experiment provided by this application, there is a nearly 55% probability that the remaining frequency offset range is maintained within ±250 Hz, and the probability of a large remaining frequency offset is smaller. It can be seen from the traditional frequency offset estimation experiment that the range of the remaining frequency offset is large, even reaching about ±5000 Hz, and the probability within ±1000 Hz is about 50%, which reflects that the estimated frequency offset is greatly different from the actual frequency offset, showing a significant gap with the method provided by this application. In addition, when using the method provided by this application for frequency offset estimation, it can be realized that at different signal-to-noise ratios, the probability that the estimated frequency offset is close to the actual frequency offset is greater, and the performance of frequency offset estimation is better. Among them, the way of the traditional frequency offset estimation experiment is that in one frame of data, a pilot is inserted at the same interval, such as dividing one frame of data into ten equal-length data blocks. A pilot is inserted after each data block, the conjugate summation operation is performed pairwise before and after each pilot, and then it is converted into an angle to obtain the corresponding frequency offset value. Finally, the average value of the frequency offset values is taken to obtain the final frequency offset estimated by the traditional frequency offset estimation method. Figure 3 In Figure 4 both, the abscissa represents the remaining frequency offset, with the unit of hertz (Hz), and the ordinate represents the probability distribution, with the unit of (%).

[0079] Step 105: The receiving end corrects the deviation of the second data transmission frame based on the frequency offset estimation value to obtain the first data transmission frame.

[0080] In the embodiment of this application, through the data-assisted feedforward carrier synchronization working mode, the frequency offset estimation value is calculated, and the receiving end of data transmission can correct the deviation of the second data transmission frame by adjusting the frequency of the local oscillator. The corrected frequency-domain signal is closer to the data transmission frame of the transmitting end of data transmission, that is, the first data transmission frame, thereby improving the accuracy of data demodulation.

[0081] In addition, during the transmission of the first data transmission frame, the receiving end of data transmission will continuously use the pilot signal, that is, the original UW sequence, for carrier synchronization tracking, continuously estimating and correcting the deviation of the carrier frequency, and being able to maintain stable carrier synchronization while adapting to changes in channel conditions. This application can be applied to various code rates and modulation methods, and compared with the traditional method of frequency offset estimation in the time domain, this application has a lower signal-to-noise ratio threshold and higher estimation accuracy.

[0082] Although the present application provides method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on routine or non-creative labor. The order of steps listed in this embodiment is only one way among the execution orders of numerous steps and does not represent the only execution order. When the actual device or client product is executed, it may be executed in the method order shown in this embodiment or the accompanying drawings or executed in parallel (such as in an environment of parallel processors or multi-threaded processing).

[0083] As Figure 5 shown, an embodiment of the present application further provides a frequency-domain carrier synchronization device 500 based on sparse pilot frequency. The device includes: a data acquisition module 501, a data processing module 502, a frequency offset calculation module 503, and a carrier synchronization module 504, which are specifically as follows.

[0084] The data acquisition module 501 is used to generate a data sequence and an original UW sequence at the transmitter.

[0085] The data processing module 502 is used to insert the original UW sequence into the data sequence in an equally spaced post-position manner at the transmitter to obtain a first data transmission frame, and send the first data transmission frame to the receiver.

[0086] The receiver detects the received second data transmission frame to determine the maximum peak position of the frequency-domain signal.

[0087] The frequency offset calculation module 503 is used to determine a frequency offset estimation value at the receiver according to the maximum peak position of the frequency-domain signal.

[0088] The carrier synchronization module 504 is used to perform deviation correction on the second data transmission frame at the receiver based on the frequency offset estimation value to obtain the first data transmission frame.

[0089] Some modules in the device described in the present application may be described in a general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc. that perform specific tasks or implement specific abstract data types. The present application can also be practiced in a distributed computing environment, where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media including storage devices.

[0090] The devices or modules described in the above application embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. For the convenience of description, when describing the above devices, they are divided into various modules according to functions and described separately. When implementing the application embodiments, the functions of each module can be implemented in the same or multiple software and / or hardware. Of course, the module that implements a certain function can also be implemented by combining multiple sub-modules or sub-units.

[0091] The methods, devices or modules described in this application can be implemented in the form of computer-readable program codes. The controller can be implemented in any appropriate manner. For example, the controller can take the form of, for example, a microprocessor or a processor, and a computer-readable medium storing computer-readable program codes (such as software or firmware) executable by the (micro)processor, logic gates, switches, application specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C8051F320. The memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art also know that in addition to implementing the controller in the form of pure computer-readable program codes, the method steps can be logically programmed to enable the controller to be implemented in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, and embedded microcontrollers to achieve the same function. Therefore, such a controller can be considered a hardware component, and the devices included therein for implementing various functions can also be regarded as the structures within the hardware component. Or even, the devices for implementing various functions can be regarded as either software modules for implementing the method or structures within the hardware component.

[0092] The embodiments of the present application also provide a device for executing a frequency-domain carrier synchronization method based on sparse pilot channels. The device includes: a processor; a memory for storing instructions executable by the processor; when the processor executes the executable instructions, the method described in the embodiments of the present application is implemented.

[0093] The embodiments of the present application also provide a non-volatile computer-readable storage medium, on which a computer program or instructions are stored. When the computer program or instructions are executed, the method described in the embodiments of the present application is implemented.

[0094] In addition, in each embodiment of the present application, the various functional modules can be integrated into one processing module, or each module can exist independently, or two or more modules can be integrated into one module.

[0095] The above storage medium includes, but is not limited to, random access memory (English: Random Access Memory; abbreviation: RAM), read-only memory (English: Read-Only Memory; abbreviation: ROM), cache (English: Cache), hard disk drive (English: Hard Disk Drive; abbreviation: HDD), or memory card (English: Memory Card). The memory can be used to store computer program instructions.

[0096] From the description of the above embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary hardware. Based on such an 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, or can also be reflected in the implementation process of data migration. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, mobile terminal, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0097] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments. All or part of this application can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld or portable devices, tablet devices, mobile communication terminals, multi-processor systems, microprocessor-based systems, programmable electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, and so on.

[0098] The above embodiments are only used to illustrate the technical solutions of this application, rather than to limit this application; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of this application.

Claims

1. A frequency domain carrier synchronization method based on sparse pilot, characterized in that: include: The transmitter generates a data sequence and an original UW sequence; The transmitting end inserts the original UW sequence into the data sequence in a post-positioned manner at equal intervals to obtain a first data transmission frame, and sends the first data transmission frame to the receiving end; The receiving end detects the received second data transmission frame to determine the maximum peak position of the frequency domain signal; wherein the receiving end extracts the second data transmission frame to obtain a first UW sequence; Performing correlation calculation on the first UW sequence and the original UW sequence to obtain an extracted sequence; Determining the maximum peak position of the frequency domain signal according to the extraction sequence; According to a correlation formula, correlation calculation is performed on the first UW sequence and the original UW sequence to obtain an extracted sequence; the correlation formula is as follows: ； In the formula, represents a correlation value between the first received UW sequence and the original UW sequence, that is, the extracted sequence, represents the first UW sequence received, represents the original UW sequence, represents taking the conjugate of the original UW sequence, represents the number of the first UW sequence and the original UW sequence; The receiving end determines a frequency offset estimation value according to the maximum peak position of the frequency domain signal; the receiving end determines the frequency offset estimation value according to the maximum peak position and a frequency offset estimation formula; the frequency offset estimation formula is as follows: ； In the formula, represents the frequency offset estimation value, represents the maximum peak position, represents the sampling rate, Indicates the length of the data block. represents the number of points of the fast Fourier transform; The receiving end performs deviation correction on the second data transmission frame based on the frequency offset estimation value to obtain the first data transmission frame.

2. The method according to claim 1, characterized in that After the transmitting end inserts the original UW sequence into the data sequence in an evenly spaced post-position manner to obtain a first data transmission frame, the method further includes: Performing modulation and noise adding processing on the first data transmission frame; The modulation and noise adding process includes: Performing double-sideband modulation on the baseband signal in the first data transmission frame to obtain a modulated signal; Noise is added to the modulated signal using an optimized Gaussian channel; wherein the optimized Gaussian channel includes introducing a multipath fading channel into the Gaussian channel.

3. The method according to claim 1, characterized in that: Determining the maximum peak position of the frequency domain signal according to the extraction sequence includes: Based on the extraction sequence, a fast Fourier transform method is used to perform signal conversion to determine the position of the maximum power spectrum of the frequency domain signal; The maximum peak position is determined according to the position of the maximum value power spectrum of the frequency domain signal.

4. The method according to claim 3, characterized in that The method of performing signal conversion based on the extraction sequence using a fast Fourier transform method to determine the position of the maximum power spectrum of the frequency domain signal includes: Based on the extraction sequence, a fast Fourier transform method is used to perform signal conversion to determine the power spectrum of the frequency domain signal; Traversing the power spectrum to determine a plurality of local peaks; According to the peak screening strategy, the maximum power spectrum and its corresponding frequency domain index are determined from the multiple local peaks; wherein the peak screening strategy includes taking the local peak with the highest correlation with the original UW sequence as the maximum power spectrum; Mapping the frequency domain index to the frequency axis, taking the position of the frequency corresponding to the maximum value power spectrum as the position of the maximum value power spectrum, and determining the frequency range of the frequency domain according to the position of the maximum value power spectrum; The maximum peak position of the frequency domain signal is the position of the maximum value power spectrum.

5. A device for frequency domain carrier synchronization based on sparse pilot, characterized in that: include: Data acquisition module, used for generating data sequence and original UW sequence at the transmitting end; A data processing module, configured for the transmitting end to insert the original UW sequence into the data sequence in an evenly spaced post-position manner to obtain a first data transmission frame, and to send the first data transmission frame to the receiving end; The receiving end detects the received second data transmission frame to determine the maximum peak position of the frequency domain signal; wherein the receiving end extracts the second data transmission frame to obtain a first UW sequence; Performing correlation calculation on the first UW sequence and the original UW sequence to obtain an extracted sequence; Determining the maximum peak position of the frequency domain signal according to the extraction sequence; According to a correlation formula, correlation calculation is performed on the first UW sequence and the original UW sequence to obtain an extracted sequence; the correlation formula is as follows: ； In the formula, represents a correlation value between the first received UW sequence and the original UW sequence, that is, the extracted sequence, represents the first UW sequence received, represents the original UW sequence, represents taking the conjugate of the original UW sequence, represents the number of the first UW sequence and the original UW sequence; A frequency offset calculation module is used for the receiving end to determine the frequency offset estimation value according to the maximum peak position of the frequency domain signal; the receiving end determines the frequency offset estimation value according to the maximum peak position and a frequency offset estimation formula; the frequency offset estimation formula is as follows: ； In the formula, represents the frequency offset estimation value, represents the maximum peak position, represents the sampling rate, Indicates the length of the data block. represents the number of points of the fast Fourier transform; The carrier synchronization module is used for the receiving end to perform deviation correction on the second data transmission frame based on the frequency offset estimation value to obtain the first data transmission frame.

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