Frequency offset processing method and device for OFDM signal

Abstract

The application provides a frequency offset processing method and device of an OFDM signal, which can be applied to the technical field of signal processing. The method comprises: processing an initial OFDM signal to obtain a processed OFDM signal, the processed OFDM signal comprising a main synchronization sequence and a plurality of OFDM symbols, and each OFDM symbol comprising a plurality of pilot symbols; determining a first frequency adjustment value according to a spectral line position of a high-order spectrum of the main synchronization sequence; adjusting the frequency of the processed OFDM signal to obtain an intermediate OFDM signal; for each intermediate OFDM symbol: determining a first phase adjustment value corresponding to each intermediate OFDM symbol according to the phases of a plurality of intermediate pilot symbols and the phases of theoretical pilot symbols corresponding to the plurality of intermediate pilot symbols; and adjusting the phase of the intermediate OFDM signal to obtain a target OFDM signal, the target OFDM signal comprising a plurality of target OFDM symbols.

Description

Technical Field

[0001] This application relates to the field of signal processing technology, and more specifically, to a method and apparatus for frequency offset processing of OFDM signals. Background Technology

[0002] Orthogonal Frequency Division Modulation (OFDM) is a multi-carrier modulation technique applicable to systems such as 4G / 5G cellular mobile communication systems, wireless local area networks (WLANs), and satellite internet systems. In satellite internet systems, low-Earth orbit (LEO) satellites, due to their ability to reduce transmission latency, serve as the core access service platform for both non-terrestrial networks and satellite internet systems. However, in LEO satellite internet systems, there are issues with inaccurate frequency offset processing of OFDM signals. Summary of the Invention

[0003] In view of this, this application provides a method and apparatus for frequency offset processing of OFDM signals.

[0004] One aspect of this application provides a frequency offset processing method for an OFDM signal, comprising: processing an initial OFDM signal to obtain a processed OFDM signal, wherein the initial OFDM signal is a signal transmitted from a transmitter to a receiver, the processed OFDM signal includes a master synchronization sequence and multiple OFDM symbols, each OFDM symbol including multiple pilot symbols; determining a first frequency adjustment value based on the spectral line positions of the higher-order spectrum of the master synchronization sequence; adjusting the frequency of the processed OFDM signal according to the first frequency adjustment value to obtain an intermediate OFDM signal, wherein the intermediate OFDM signal includes an intermediate master synchronization sequence corresponding to the master synchronization sequence and an intermediate master synchronization sequence corresponding to each of the multiple OFDM symbols. The corresponding intermediate OFDM symbols, each of which includes multiple intermediate pilot symbols; for each of the intermediate OFDM symbols: based on the phases of the multiple intermediate pilot symbols and the phases of the theoretical pilot symbols corresponding to the multiple intermediate pilot symbols, a first phase adjustment value corresponding to each of the intermediate OFDM symbols is determined, wherein the theoretical pilot symbols indicate the theoretical transmission phase of the intermediate pilot symbols; the phase of the intermediate OFDM signal is adjusted according to the first phase adjustment value corresponding to each of the intermediate OFDM symbols to obtain a target OFDM signal, wherein the target OFDM signal includes a target OFDM symbol corresponding to each of the multiple intermediate OFDM symbols.

[0005] Another aspect of this application provides a frequency offset processing apparatus for OFDM signals, comprising: a first obtaining module, configured to process an initial OFDM signal to obtain a processed OFDM signal, wherein the initial OFDM signal is a signal transmitted from a transmitter to a receiver, and the processed OFDM signal includes a master synchronization sequence and multiple OFDM symbols, each OFDM symbol including multiple pilot symbols; a first determining module, configured to determine a first frequency adjustment value based on the spectral line positions of the higher-order spectrum of the master synchronization sequence; and a second obtaining module, configured to adjust the frequency of the processed OFDM signal according to the first frequency adjustment value to obtain an intermediate OFDM signal, wherein the intermediate OFDM signal includes an intermediate master synchronization sequence corresponding to the master synchronization sequence and multiple OFDM symbols. Each of the M symbols corresponds to an intermediate OFDM symbol, and each of the intermediate OFDM symbols includes multiple intermediate pilot symbols; the second determining module is used for each of the intermediate OFDM symbols to: determine a first phase adjustment value corresponding to each of the intermediate OFDM symbols based on the phase of each of the multiple intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the multiple intermediate pilot symbols, wherein the theoretical pilot symbol indicates the theoretical transmission phase of the intermediate pilot symbol; the third obtaining module is used to adjust the phase of the intermediate OFDM signal according to the first phase adjustment value corresponding to each of the intermediate OFDM symbols to obtain a target OFDM signal, wherein the target OFDM signal includes a target OFDM symbol corresponding to each of the multiple intermediate OFDM symbols.

[0006] Another aspect of this application provides an electronic device comprising:

[0007] One or more processors;

[0008] Memory, used to store one or more programs.

[0009] When the above one or more programs are executed by the above one or more processors, the above one or more processors implement the methods described above.

[0010] Another aspect of this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed, are used to implement the methods described above.

[0011] Another aspect of this application provides a computer program product including computer-executable instructions that, when executed, implement the method described above.

[0012] According to embodiments of this application, the initial OFDM signal is processed to obtain a processed OFDM signal including a master synchronization sequence and multiple OFDM symbols. A first frequency adjustment value is determined based on the spectral line positions of the higher-order spectrum of the master synchronization sequence in the time domain, and the frequency of the processed OFDM signal is adjusted for the first time based on the first frequency adjustment value, thus achieving the initial adjustment of the processed OFDM signal. Furthermore, based on the variation pattern of the pilot symbols during transmission, a first phase adjustment value based on the frequency domain is determined for each intermediate OFDM symbol, thereby performing a second adjustment on the intermediate OFDM signal. The first phase adjustment value is calculated using the phase relationship between the intermediate pilot symbols and the theoretical pilot symbols in the intermediate OFDM signal, achieving frequency offset processing without relying on ephemeris information, reducing the possibility of errors in frequency offset estimation, and further improving the accuracy of OFDM signal processing by having a first phase adjustment value for each intermediate OFDM symbol. Attached Figure Description

[0013] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0014] Figure 1 An exemplary system architecture for a frequency offset processing method and apparatus for OFDM signals, applicable according to embodiments of this application, is shown.

[0015] Figure 2 A flowchart of a frequency offset processing method for OFDM signals according to an embodiment of this application is shown.

[0016] Figure 3 A schematic diagram of a fourth-order higher-order spectrum according to an embodiment of this application is shown.

[0017] Figure 4A A schematic diagram showing the distribution of symbols of the second intermediate OFDM symbol according to an embodiment of this application is shown.

[0018] Figure 4B A schematic diagram showing the symbol distribution of the 11th intermediate OFDM symbol according to an embodiment of this application is shown.

[0019] Figure 4C A schematic diagram showing the distribution of symbols for the 21st intermediate OFDM symbol according to an embodiment of this application is provided.

[0020] Figure 5 A schematic diagram showing the symbol phase deviation value and the estimated value of the cumulative phase deviation of a high-quality intermediate pilot symbol according to an embodiment of this application is provided.

[0021] Figure 6The diagram illustrates the phase cumulative deviation estimate, the first phase adjustment value, and the fitting curve corresponding to the first phase adjustment value according to an embodiment of this application.

[0022] Figure 7A A schematic diagram showing the target OFDM signal obtained by first phase adjustment according to an embodiment of this application is illustrated.

[0023] Figure 7B A schematic diagram showing the target OFDM signal obtained by the second frequency adjustment value and the second phase adjustment value according to an embodiment of this application is illustrated.

[0024] Figure 8 A block diagram of an OFDM signal frequency offset processing apparatus according to an embodiment of this application is shown.

[0025] Figure 9 A block diagram of an electronic device suitable for implementing the frequency offset processing method for OFDM signals described above, according to an embodiment of this application, is shown. Detailed Implementation

[0026] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0029] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0030] Some low-Earth orbit (LEO) satellite communication systems primarily support voice and low-speed data services, failing to meet users' demands for high-capacity data, video, and virtual reality (VR) technologies. OFDM technology, however, can achieve high-bandwidth data transmission. Therefore, applying OFDM technology to uplink and downlink user links in LEO satellite communication systems has resulted in transmission rate increases of hundreds or even thousands of times. In fact, LEO satellites have been tested to support user link transmission rates as high as 512 Mbps. Compared to high-Earth orbit (HEO) satellites and terrestrial wireless communication systems, LEO satellites exhibit extremely high relative mobility with ground terminals, and their radial velocity displays highly dynamic variations.

[0031] The communication frequency bands of low-Earth orbit (LEO) satellite communication systems have expanded to the Ku band (approximately 12-18 GHz) and the Ka band (approximately 26.5-40 GHz), resulting in a wide range and rapidly changing Doppler frequency offset in the OFDM signals transmitted by LEO satellite communication systems. Furthermore, due to the difficulty in achieving real-time clock synchronization between satellite and ground systems, and the instability of local oscillators, the OFDM signals received at the receiver also exhibit frequency offset. Therefore, the application of OFDM technology in the user link of LEO satellite communication systems requires addressing the sampling frequency offset problem caused by the wide range and high dynamics of Doppler frequency offset.

[0032] During normal communication, the user terminal, i.e., the receiving end, can typically calculate the Doppler frequency shift using the precise satellite ephemeris information broadcast by the low-Earth orbit satellite and its own position information. It can then perform pre-compensation for the uplink signal frequency offset before transmission, or perform precise frequency offset compensation for the received downlink signal. Low-Earth orbit satellites can also perform pre-compensation for transmitted signal frequency offset and compensation for received signal frequency offset in a similar manner.

[0033] However, when low-Earth orbit satellite communication systems malfunction or satellite / terminal devices age, satellite ephemeris information or the location of user terminals may be inaccurate, leading to errors in Doppler frequency shift calculations and consequently inaccurate compensation at the transmitting / receiving end.

[0034] Integer multiple frequency offset estimation can be achieved based on pilot symbols in the frequency domain. For example, pseudo-random pilot symbols can be used to estimate the correlation peak between the frequency domain pilot symbol and the theoretical pilot symbol of a single OFDM symbol, and the frequency offset can be estimated based on the integer multiple of the correlation peak estimate. Fractional multiple frequency offset estimation can also be achieved based on pilot symbols in the frequency domain. For example, the phase difference between the pilot symbols at the receiving end of adjacent OFDM symbols can be calculated using the same pilot symbols on different OFDM symbols, and then the frequency offset can be calculated. However, pilot symbols on different OFDM symbols also exhibit pseudo-random characteristics, making it difficult to directly use the phase difference between adjacent received symbols for frequency offset estimation. Furthermore, when using frequency domain pilot symbols for frequency offset estimation, the calculation of the phase difference between the pilot symbol at the receiving end and the theoretical symbol has a periodic cyclical characteristic. When noise, interference, or the phase difference accumulates to the periodic boundary, the calculated phase difference will exhibit periodic cyclical characteristics, affecting the accuracy of the frequency offset estimation, especially when the frequency offset changes dynamically with the OFDM symbol. Meanwhile, the high-speed motion of low-Earth orbit satellites can cause compression or expansion of OFDM symbols at the receiver, resulting in time-varying sampling rates and timing estimates for different OFDM symbols. Furthermore, inaccurate timing of individual OFDM symbols can also lead to inaccurate frequency offset estimation based on frequency domain pilots.

[0035] In view of this, embodiments of this application provide a frequency offset processing method for OFDM signals, comprising: processing an initial OFDM signal to obtain a processed OFDM signal, wherein the initial OFDM signal is a signal transmitted from a transmitter to a receiver, the processed OFDM signal includes a master synchronization sequence and multiple OFDM symbols, each OFDM symbol including multiple pilot symbols; determining a first frequency adjustment value based on the spectral line positions of the higher-order spectrum of the master synchronization sequence; adjusting the frequency of the processed OFDM signal according to the first frequency adjustment value to obtain an intermediate OFDM signal, wherein the intermediate OFDM signal includes an intermediate master synchronization sequence corresponding to the master synchronization sequence and multiple OFDM symbols. Each symbol corresponds to an intermediate OFDM symbol, and each intermediate OFDM symbol includes multiple intermediate pilot symbols. For each intermediate OFDM symbol: based on the phases of the multiple intermediate pilot symbols and the phases of the theoretical pilot symbols corresponding to the multiple intermediate pilot symbols, a first phase adjustment value corresponding to each intermediate OFDM symbol is determined, wherein the theoretical pilot symbols indicate the theoretical transmission phase of the intermediate pilot symbols; the phase of the intermediate OFDM signal is adjusted according to the first phase adjustment value corresponding to each intermediate OFDM symbol to obtain the target OFDM signal, wherein the target OFDM signal includes the target OFDM symbols corresponding to the multiple intermediate OFDM symbols.

[0036] Figure 1 An exemplary system architecture for a frequency offset processing method and apparatus for OFDM signals, applicable according to embodiments of this application, is shown. It should be noted that... Figure 1 The examples shown are merely examples of system architectures that can be applied to the embodiments of this application, in order to help those skilled in the art understand the technical content of this application, but do not mean that the embodiments of this application cannot be used in other devices, systems, environments or scenarios.

[0037] like Figure 1 As shown, the system architecture 100 according to this embodiment may include a transmitter 101 and a receiver 102. The transmitter 101 may be, for example, a low-Earth orbit satellite, and the receiver 102 may be, for example, various electronic devices or servers, including but not limited to smartphones, tablets, laptops, and desktop computers.

[0038] The initial OFDM signal can be a signal sent from the transmitter 101 to the receiver 102, or a signal sent from the receiver 102 to the transmitter 101. After receiving the initial OFDM signal, the receiver 102 can execute the frequency offset processing method for OFDM signals according to the embodiments of this application.

[0039] It should be understood that Figure 1 The number of transmitters and receivers shown is merely illustrative. Depending on implementation requirements, there can be any number of transmitters and receivers.

[0040] Figure 2 A flowchart of a frequency offset processing method for OFDM signals according to an embodiment of this application is shown.

[0041] like Figure 2 As shown, the method may include operations S210~S250.

[0042] In operation S210, the initial OFDM signal is processed to obtain the processed OFDM signal.

[0043] The initial OFDM signal is the signal sent from the transmitter to the receiver. Processing the OFDM signal includes the master synchronization sequence and multiple OFDM symbols, each of which includes multiple pilot symbols.

[0044] In operation S220, the first frequency adjustment value is determined based on the spectral line positions of the higher-order spectrum of the master synchronization sequence.

[0045] In operation S230, the frequency of the processed OFDM signal is adjusted according to the first frequency adjustment value to obtain an intermediate OFDM signal.

[0046] The intermediate OFDM signal includes an intermediate master synchronization sequence corresponding to the master synchronization sequence, and intermediate OFDM symbols corresponding to multiple OFDM symbols. Each intermediate OFDM symbol includes multiple intermediate pilot symbols.

[0047] In operation S240, for each intermediate OFDM symbol: based on the phase of each of the multiple intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the multiple intermediate pilot symbols, determine the first phase adjustment value corresponding to each intermediate OFDM symbol.

[0048] The theoretical pilot symbol indicates the theoretical transmission phase of the intermediate pilot symbol.

[0049] In operation S250, the phase of the intermediate OFDM signal is adjusted according to the first phase adjustment value corresponding to each intermediate OFDM symbol to obtain the target OFDM signal.

[0050] The target OFDM signal includes the target OFDM symbol corresponding to each of the multiple intermediate OFDM symbols.

[0051] The initial OFDM signal can be a wideband signal. Processing the initial OFDM signal can involve analyzing its waveform to obtain a processed OFDM signal.

[0052] The master synchronization sequence can be a sequence used to synchronize OFDM signals. OFDM symbols can be signals modulated by multiple orthogonal subcarriers. Each subcarrier can correspond to a pilot symbol without information or a constellation symbol carrying information. Pilot symbols can be symbols known to both the receiver and transmitter for determining the signal phase. Since each subcarrier will produce a certain phase shift, pilot symbols are inserted into the initial OFDM signal to provide a phase reference, allowing the receiver to estimate the signal phase upon receiving the signal.

[0053] Higher-order spectra provide a better view of the frequency distribution of the master synchronization sequence. Since the master synchronization sequence is used for synchronization, it is the earliest part transmitted to the receiver in the initial OFDM signal. The frequency offset of the master synchronization sequence can be determined based on the spectral line positions of its higher-order spectra, thereby determining the first frequency adjustment value. The frequency of the processed OFDM signal is then adjusted according to this first frequency adjustment value to obtain the intermediate OFDM signal. For example, the frequency of the master synchronization sequence and the frequencies of multiple OFDM symbols can be adjusted based on the first frequency adjustment value to obtain the intermediate master synchronization sequence and the corresponding intermediate OFDM symbols for each of the multiple OFDM symbols.

[0054] Because signal transmission has a certain timing sequence, the frequency offset of each OFDM symbol is different, with later OFDM symbols having larger offsets. The master synchronization sequence is earlier in the time sequence; therefore, the first frequency adjustment value obtained from the master synchronization sequence may be more applicable to earlier OFDM symbols. After adjusting the frequency of all OFDM symbols using a uniform first frequency adjustment value, intermediate OFDM signals will still have frequency offsets. Since both the receiver and transmitter possess theoretical pilot symbols as a basis, i.e., the theoretical transmission phase of the intermediate pilot symbols, processing can be performed on a per-intermediate OFDM symbol basis. For example, the combined phase offset of an intermediate OFDM symbol can be determined based on the phases of each of the multiple intermediate pilot symbols and the phases of their corresponding theoretical pilot symbols, and the first phase adjustment value can be determined based on this combined phase offset.

[0055] The phase of the intermediate OFDM signal can be adjusted according to the first phase adjustment value corresponding to each intermediate OFDM symbol to obtain the target OFDM symbol corresponding to each intermediate OFDM symbol, thereby obtaining the target OFDM signal.

[0056] According to embodiments of this application, the initial OFDM signal is processed to obtain a processed OFDM signal including a master synchronization sequence and multiple OFDM symbols. A first frequency adjustment value is determined based on the spectral line positions of the higher-order spectrum of the master synchronization sequence in the time domain, and the frequency of the processed OFDM signal is adjusted for the first time based on the first frequency adjustment value, thus achieving the initial adjustment of the processed OFDM signal. Furthermore, based on the variation pattern of the pilot symbols during transmission, a first phase adjustment value based on the frequency domain is determined for each intermediate OFDM symbol, thereby performing a second adjustment on the intermediate OFDM signal. The first phase adjustment value is calculated using the phase relationship between the intermediate pilot symbols and the theoretical pilot symbols in the intermediate OFDM signal, achieving frequency offset processing without relying on ephemeris information, reducing the possibility of errors in frequency offset estimation, and further improving the accuracy of OFDM signal processing by having a first phase adjustment value for each intermediate OFDM symbol.

[0057] According to an embodiment of this application, processing an initial OFDM signal to obtain a processed OFDM signal may include: sampling the initial OFDM signal based on a sampling signal to obtain a sampled OFDM signal; performing a coarse parameter estimation on the sampled OFDM signal to obtain a coarse parameter estimation result for the sampled OFDM signal, wherein the coarse parameter estimation result includes at least one of the signal start time, signal end time, or signal frequency range of the sampled OFDM signal; and preprocessing the sampled OFDM signal based on the coarse parameter estimation result to obtain a processed OFDM signal.

[0058] The sampled signal can be a wideband sampled signal, and its frequency can be greater than the frequency of the initial OFDM signal. For example, the frequency of the sampled signal can be expressed as F. s1 The initial frequency of the initial OFDM signal can be expressed as F. star F s1 ≥F star F s1 =F star M1 / M2, M2≥1, M1>0, M1 and M2 are both positive integers.

[0059] Coarse parameter estimation can be performed on sampled OFDM signals, for example, in the time domain, frequency domain, time-frequency domain, or other transform domains. The coarse parameter estimation result is obtained, and the signal start time of the coarse parameter estimation result can be expressed as T. start The signal end time can be expressed as T. end The signal frequency range can be represented as [F1, F2].

[0060] The coarse parameter estimation results indicate the start, end, and frequency-related information of the sampled OFDM signal. Therefore, the sampled OFDM signal can be processed based on the coarse parameter estimation results to obtain the processed OFDM signal.

[0061] According to embodiments of this application, preprocessing includes at least one of time slicing, zero-IF shifting, upsampling, or filtering.

[0062] Based on the coarse parameter estimation results, the sampled OFDM signal is preprocessed to obtain a processed OFDM signal, including: time slicing the sampled OFDM signal according to the signal start time and signal end time so that the obtained processed OFDM signal is a signal within a preset time period; and / or zero-IF shifting the sampled OFDM signal according to the signal frequency range so that the signal center frequency of the obtained processed OFDM signal is the target frequency; and / or upsampling the sampled OFDM signal according to the sampling frequency of the sampled signal and the initial frequency of the initial OFDM signal so that the sampling frequency of the obtained processed OFDM signal is the target sampling frequency; and / or filtering the sampled OFDM signal according to the signal frequency range so that the obtained processed OFDM signal is a signal within a preset frequency band.

[0063] Based on the signal start time T start and signal end time T end Retention time margin Get the preset time period The sampled OFDM signal is preprocessed by time slicing according to a preset time period to obtain the processed OFDM signal.

[0064] It is also possible to perform up-conversion or down-conversion processing on the signal based on the signal frequency range [F1, F2], so that the signal center frequency changes to the vicinity of the target frequency, for example, 0.

[0065] The sampled OFDM signal can be upsampled; for example, the upsampling frequency can be F. s1，up =M2F s1 To make the sampling frequency of the obtained processed OFDM signal the target sampling frequency, the target sampling frequency is equal to the upsampling sampling frequency F. s1，up .

[0066] Frequency margin can be reserved based on the signal frequency range [F1, F2]. To obtain the preset frequency band The signal outside the preset frequency band of the sampled OFDM signal is filtered to obtain the processed OFDM signal.

[0067] According to embodiments of this application, preprocessing can increase the effective segments of the OFDM signal, reduce useless signals in the signal, and amplify the signal, thereby improving the signal processing efficiency.

[0068] According to an embodiment of this application, determining a first frequency adjustment value based on the spectral line position of the higher-order spectrum of the master synchronization sequence may include: determining a first frequency adjustment value based on the center spectral line of the higher-order spectrum of the master synchronization sequence; and / or determining a first frequency adjustment value based on the adjacent spectral lines of the center spectral line of the higher-order spectrum of the master synchronization sequence.

[0069] The master synchronization sequence signal is a time-domain synchronization symbol sequence, which adopts digital phase modulation or digital amplitude-phase modulation, including but not limited to binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), and 8-ary phase-shift keying (8PSK).

[0070] The master synchronization sequence can be extracted from the processed OFDM signal, and its higher-order spectrum can be calculated. The first frequency adjustment value can be calculated based on the spectral line positions of the higher-order spectrum. The order of the higher-order spectrum can be determined based on the modulation scheme of the master synchronization sequence.

[0071] The first frequency adjustment value can be calculated based on the frequency of the center spectral line of the higher-order spectrum of the master synchronization sequence. For example, the frequency corresponding to the center spectral line is... The first frequency adjustment value is L represents the order of the higher-order spectrum.

[0072] The first frequency adjustment value can also be calculated based on the frequencies of adjacent spectral lines to the center spectral line of the higher-order spectrum of the main synchronization sequence. For example, the frequencies of adjacent spectral lines to the center spectral line of the higher-order spectrum of the main synchronization sequence are respectively... and The first frequency adjustment value is .

[0073] Figure 3 A schematic diagram of a fourth-order higher-order spectrum according to an embodiment of this application is shown.

[0074] like Figure 3 As shown, taking QPSK modulation as an example, the order of QPSK is L=4, and the true frequency offset is set to 150kHz. The frequency of the center spectral line (the position of the spectral line marked by the triangle) of the higher-order spectrum of the main synchronization sequence is used as an example. =549.32kHz, the first frequency adjustment value can be determined. =137.32kHz. Based on the frequencies of the spectral lines adjacent to the center line of the higher-order spectrum of the main synchronization sequence (the positions of the spectral lines are marked with circles). =-239.31MHz and =240.60MHz, the first frequency adjustment value can be determined. =160.22kHz.

[0075] Figure 4A A schematic diagram showing the distribution of symbols of the second intermediate OFDM symbol according to an embodiment of this application is shown. Figure 4B A schematic diagram showing the symbol distribution of the 11th intermediate OFDM symbol according to an embodiment of this application is shown. Figure 4C A schematic diagram showing the distribution of symbols for the 21st intermediate OFDM symbol according to an embodiment of this application is provided.

[0076] Taking an OFDM signal containing 100 OFDM symbols as an example, the distribution diagram of the intermediate pilot symbols and constellation symbols of some intermediate OFDM symbols obtained after adjusting the OFDM signal using the first frequency adjustment value is as follows: Figure 4A , Figure 4B and Figure 4C As shown (intermediate pilot symbols and constellation symbols are represented as dots in the figure and are not distinguished), it can be seen that after adjusting the first frequency adjustment value, the frequency deviation on the second OFDM symbol is relatively small, and there is basically no crosstalk between the intermediate pilot symbols and constellation symbols. However, for subsequent OFDM symbols, such as the 11th and 21st, the crosstalk between the intermediate pilot symbols and constellation symbols gradually increases, requiring further fine-tuning of the frequency offset correction.

[0077] According to embodiments of this application, the intermediate OFDM signal can be downsampled to remove the training symbol sequence and cyclic prefix, and demultiplexing operations can be performed. The downsampling frequency can be determined based on F... s1 =F star M1 / M2 is determined; for example, the downsampling frequency can be F. s2，down =M1F s1 After removing the training symbol sequence and cyclic prefix from the intermediate OFDM signal and demultiplexing it, the digital modulation symbols on each subcarrier of the intermediate OFDM signal can be obtained. The digital modulation symbols include intermediate pilot symbols and constellation symbols.

[0078] According to the embodiments of this application, the first frequency deviation estimation is achieved based on the spectral lines by utilizing the higher-order spectral characteristics of the time-domain master synchronization sequence after upsampling. This method is not sensitive to the timing error of the received signal at the receiving end and can achieve good frequency deviation estimation performance in the initial stage of receiving end processing, completing the estimation of integer multiple frequency deviation and some fractional multiple frequency deviation.

[0079] According to an embodiment of this application, determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on the phase of each of the multiple intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the multiple intermediate pilot symbols may include: determining a multiple high-quality intermediate pilot symbols from the multiple intermediate pilot symbols based on the symbol transmission quality of each of the multiple intermediate pilot symbols; and determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on the phase of each of the multiple high-quality intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the multiple high-quality intermediate pilot symbols.

[0080] During the initial OFDM signal transmission process, the signal may experience attenuation, loss, errors, etc. Therefore, the obtained intermediate pilot symbols may also have problems. The frequency of the intermediate pilot symbols can be used as the standard for determining the symbol transmission quality. By detecting the frequency of the intermediate pilot symbols, the symbol transmission quality of each intermediate pilot symbol can be determined, and intermediate pilot symbols that meet certain requirements in terms of frequency, etc., can be identified as high-quality intermediate pilot symbols.

[0081] A standard phase value can be set, and the phase of the high-quality intermediate pilot symbol and the phase of the corresponding theoretical pilot symbol can be compared with the standard phase value to determine the difference between the phase of the high-quality intermediate pilot symbol and the standard phase value, as well as the difference between the phase of the theoretical pilot symbol and the standard phase value. Based on the two differences, the phase difference between the high-quality intermediate pilot symbol and the theoretical pilot symbol can be determined. Then, the phase difference between each of the multiple high-quality intermediate pilot symbols and the phase of their respective theoretical pilot symbols can be determined. Finally, the first phase adjustment value corresponding to the intermediate OFDM symbol can be determined based on the average of the multiple differences.

[0082] According to an embodiment of this application, determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on the phase of each of the plurality of high-quality intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the plurality of high-quality intermediate pilot symbols may include: determining a symbol phase deviation value corresponding to each of the plurality of high-quality intermediate pilot symbols based on the phase of each of the plurality of high-quality intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the plurality of high-quality intermediate pilot symbols; and determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on the multiple symbol phase deviation values.

[0083] The phase of a high-quality intermediate pilot symbol can be compared with the phase of the corresponding theoretical pilot symbol to determine the symbol phase deviation value between the phase of the high-quality intermediate pilot symbol and the phase of the theoretical pilot symbol. Then, the symbol phase deviation values ​​between the phases of multiple high-quality intermediate pilot symbols and their respective theoretical pilot symbols can be determined. Finally, the first phase adjustment value corresponding to the intermediate OFDM symbol can be determined based on the average value of the multiple symbol phase deviation values.

[0084] According to an embodiment of this application, determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on multiple symbol phase deviation values ​​may include: determining a target number of multiple symbol phase deviation values ​​within a target phase deviation value range; correcting the multiple symbol phase deviation values ​​when the target number is greater than a preset number threshold to obtain corrected symbol phase deviation values ​​corresponding to each of the multiple symbol phase deviation values; determining a first phase adjustment value based on the multiple corrected symbol phase deviation values; and determining a first phase adjustment value based on the multiple symbol phase deviation values ​​when the target number is less than or equal to a preset number threshold.

[0085] The symbol phase deviation between the phase of the p-th high-quality intermediate pilot symbol of the n-th intermediate OFDM symbol and the phase of the theoretical pilot symbol can be expressed as follows: The range of values ​​is (-π, π]. , Indicates the number of intermediate OFDM symbols. , This indicates the number of high-quality intermediate pilot symbols for each intermediate OFDM symbol.

[0086] Since the range of symbol phase deviation is (-π, π], when the phase error caused by Doppler frequency offset is close to the boundary of the range (-π or π), due to non-ideal factors such as the actual transmission environment and noise, the calculated symbol phase deviation value may flip from near -π to near π, or from near π to near -π. This can lead to variations within the same intermediate OFDM symbol. The phase deviation value of a high-quality intermediate pilot symbol may be partially located near -π and partially near π. If directly... Averaging the values ​​of high-quality intermediate pilot symbols will result in a large deviation between the cumulative phase deviation of the intermediate OFDM symbol and the true value.

[0087] Therefore, for each intermediate OFDM symbol, determine The distribution of the symbol phase deviation values ​​of each high-quality intermediate pilot symbol is used to determine the number of targets within the target phase deviation value range. + The target phase deviation value can be in the range of <-π / 2 and >π / 2. This indicates the quantity of <-π / 2. It represents the quantity greater than π / 2.

[0088] You can set a preset quantity threshold. As an example, It can be .

[0089] exist + Greater than In cases where the number of phase deviation values ​​is large, multiple symbol phase deviation values ​​can be corrected to obtain the corrected symbol phase deviation value relative to the p-th high-quality intermediate pilot symbol of the n-th intermediate OFDM symbol. Calculate and judge Is it greater than π? If it is greater than π, then determine the estimated phase cumulative deviation of the nth intermediate OFDM symbol as follows: ,otherwise .

[0090] exist + Less than or equal to In cases where the number of phase deviation values ​​is relatively small, the estimated cumulative phase deviation of the nth intermediate OFDM symbol can be determined directly based on the phase deviation values ​​of multiple symbols. .

[0091] Figure 5 A schematic diagram showing the symbol phase deviation value and the estimated value of the cumulative phase deviation of a high-quality intermediate pilot symbol according to an embodiment of this application is provided.

[0092] like Figure 5 As shown, the symbol phase deviation value of a high-quality intermediate pilot symbol is as follows: Figure 5 The blue symbol in the figure represents the estimated phase cumulative deviation, as shown below. Figure 5 As shown by the red symbol in the image.

[0093] Based on the phase cumulative deviation estimate and the phase jump of n, the phase of each intermediate OFDM symbol can be corrected to obtain the first phase adjustment value of each intermediate OFDM symbol.

[0094] According to an embodiment of this application, by statistically analyzing the distribution of phase deviation values, the phase deviation values ​​can be corrected, thereby reducing the problem that the deviation of the first phase adjustment value is high due to the deviation of the phase deviation values.

[0095] According to an embodiment of this application, when the target number is greater than a preset number threshold, correcting multiple symbol phase deviation values ​​to obtain corrected symbol phase deviation values ​​corresponding to each of the multiple symbol phase deviation values ​​may include: when the target number is greater than the preset number threshold and the symbol phase deviation value is negative, adjusting the symbol phase deviation value according to the value range of the symbol phase deviation value to obtain corrected symbol phase deviation values ​​corresponding to each of the multiple symbol phase deviation values; when the target number is greater than the preset number threshold and the symbol phase deviation value is not negative, obtaining corrected symbol phase deviation values ​​corresponding to each of the multiple symbol phase deviation values ​​based on the symbol phase deviation value.

[0096] In symbol phase deviation value In this case, the symbol phase deviation value can be adjusted according to the range of the symbol phase deviation value, i.e., 2π, to obtain the corrected symbol phase deviation value. .

[0097] In symbol phase deviation value In this case, the corrected symbol phase deviation value can be obtained directly from the symbol phase deviation value, that is... .

[0098] According to embodiments of this application, the phase change characteristics of frequency domain pilot symbols are utilized to perform joint frequency offset estimation of multiple OFDM symbols, obtaining fractional frequency offsets and phase deviations. First, this method solves the problem of cyclic phase differences caused by non-ideal factors such as noise interference or phase accumulation deviations by performing initial value calculation, threshold judgment, and rotation correction on the phase differences between multiple high-quality intermediate pilot symbols and theoretical pilot symbols in the frequency domain for each intermediate OFDM symbol. This allows for the calculation of the correct cumulative phase deviation of the intermediate OFDM symbol. Second, this method performs joint frequency offset estimation of multiple symbols based on the cumulative phase deviations of multiple intermediate OFDM symbols. The characteristics of phase accumulation deviation ensure that even with different timing errors remaining in each intermediate OFDM symbol, precise frequency offset estimation can still be achieved. Furthermore, the joint processing of multiple adjacent intermediate OFDM symbols further improves the robustness of the frequency offset estimation, solving the problem of inaccurate frequency offset estimation caused by channel environment and sudden interference affecting intermediate OFDM symbols.

[0099] According to an embodiment of this application, adjusting the phase of an intermediate OFDM signal based on a first phase adjustment value corresponding to each intermediate OFDM symbol may include: fitting the first phase adjustment value corresponding to each intermediate OFDM symbol to obtain a second frequency adjustment value and a second phase adjustment value; adjusting the intermediate OFDM signal based on the second frequency adjustment value and the second phase adjustment value to obtain a target OFDM signal.

[0100] After obtaining the first phase adjustment value, the first phase adjustment value corresponding to each intermediate OFDM symbol can be further fitted. Multiple first phase adjustment values ​​can be used for fitting. Fitting methods can include linear fitting, polynomial fitting, exponential fitting, etc., ultimately yielding the second frequency adjustment value and the second phase adjustment value.

[0101] The intermediate OFDM signal can be adjusted using the second frequency adjustment value and the second phase adjustment value to obtain the target OFDM signal.

[0102] According to the embodiments of this application, during the execution of the frequency offset processing method for OFDM signals in the embodiments of this application, or after obtaining the target OFDM signal, signal timing deviation estimation and compensation can be performed, and channel equalization and OFDM demultiplexing can be completed to obtain the demodulated constellation symbols.

[0103] Figure 6 The diagram illustrates the phase cumulative deviation estimate, the first phase adjustment value, and the fitting curve corresponding to the first phase adjustment value according to an embodiment of this application.

[0104] like Figure 6 As shown, the estimated phase cumulative deviation is represented by a red cross in the figure, and the first phase adjustment value is represented by a blue circle. A fitted curve is obtained based on the first phase adjustment value, as shown by the solid green line in the figure. Based on the slope of the fitted curve, the second frequency adjustment value can be determined to be -10.73kHz, and the second phase adjustment value to be -2.374rad using a formula.

[0105] Figure 7A A schematic diagram showing the target OFDM signal obtained by first phase adjustment according to an embodiment of this application is illustrated.

[0106] like Figure 7A As shown, the target OFDM signal is obtained by compensating the corresponding phase of each intermediate OFDM symbol using the first phase adjustment value. It can be seen that the phase clustering of symbols on the subcarriers of each target OFDM symbol is good. This method utilizes the phase accumulation deviation to directly perform phase rotation operations on the subcarrier symbols in the frequency domain, resulting in low computational complexity and excellent performance under favorable channel conditions.

[0107] Figure 7BA schematic diagram showing the target OFDM signal obtained by the second frequency adjustment value and the second phase adjustment value according to an embodiment of this application is illustrated.

[0108] like Figure 7B As shown, the intermediate OFDM signal is adjusted according to the second frequency adjustment value and the second phase adjustment value to obtain the target OFDM signal. It can be seen that the symbol phase clustering on the subcarriers of each target OFDM symbol is good. This method uses the joint frequency offset estimation results of multiple symbols to perform time-domain frequency offset compensation, and performs frequency offset compensation in the frequency domain according to the estimated frequency offset value, which can better adapt to scenarios with large noise and interference.

[0109] According to embodiments of this application, the first frequency adjustment value of the OFDM signal frequency offset processing method is based on the master synchronization sequence. The estimation method is insensitive to the timing error of the signal at the receiving end, and can achieve good frequency offset estimation performance in the initial stage of signal processing at the receiving end. The first phase adjustment value is based on the intermediate pilot symbol in the frequency domain. The phase period rotation problem caused by non-ideal factors such as noise interference or the accumulation of phase offset is solved by the designed phase cumulative deviation calculation method. The high-precision estimation problem of fractional frequency offset in the case of time-varying timing deviation is solved by frequency offset estimation and correction based on phase cumulative deviation. Furthermore, two examples of frequency offset compensation for intermediate OFDM signals are proposed, which have the advantages of low computational complexity or high noise and interference resistance performance for different scenarios.

[0110] Figure 8 A block diagram of an OFDM signal frequency offset processing apparatus according to an embodiment of this application is shown.

[0111] like Figure 8 As shown, the frequency offset processing device 800 for OFDM signals includes a first obtaining module 810, a first determining module 820, a second obtaining module 830, a second determining module 840, and a third obtaining module 850.

[0112] The first obtaining module 810 is used to process the initial OFDM signal to obtain a processed OFDM signal. The initial OFDM signal is a signal sent from the transmitting end to the receiving end. The processed OFDM signal includes a master synchronization sequence and multiple OFDM symbols, and each OFDM symbol includes multiple pilot symbols.

[0113] The first determining module 820 is used to determine the first frequency adjustment value based on the spectral line positions of the higher-order spectrum of the master synchronization sequence.

[0114] The second obtaining module 830 is used for each of the intermediate OFDM symbols to adjust the frequency of the processed OFDM signal according to the first frequency adjustment value to obtain an intermediate OFDM signal, wherein the intermediate OFDM signal includes an intermediate main synchronization sequence corresponding to the main synchronization sequence and intermediate OFDM symbols corresponding to each of the multiple OFDM symbols, and each intermediate OFDM symbol includes multiple intermediate pilot symbols.

[0115] The second determining module 840 is used for each intermediate OFDM symbol to determine a first phase adjustment value corresponding to each intermediate OFDM symbol based on the phase of each of the multiple intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the multiple intermediate pilot symbols, wherein the theoretical pilot symbol indicates the theoretical transmission phase of the intermediate pilot symbol.

[0116] The third obtaining module 850 is used to adjust the phase of the intermediate OFDM signal according to the first phase adjustment value corresponding to each intermediate OFDM symbol to obtain the target OFDM signal, wherein the target OFDM signal includes the target OFDM symbol corresponding to each of the multiple intermediate OFDM symbols.

[0117] According to an embodiment of this application, a second determining module 840 for determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on the phase of each of the plurality of intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the plurality of intermediate pilot symbols includes a first determining submodule and a second determining submodule.

[0118] The first determining submodule is used to determine multiple high-quality intermediate pilot symbols from multiple intermediate pilot symbols based on the symbol transmission quality of each of the multiple intermediate pilot symbols.

[0119] The second determining submodule is used to determine the first phase adjustment value corresponding to each intermediate OFDM symbol based on the phase of each of the multiple high-quality intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the multiple high-quality intermediate pilot symbols.

[0120] According to an embodiment of this application, a second determining submodule for determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on the phase of each of the plurality of high-quality intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the plurality of high-quality intermediate pilot symbols includes a first determining unit and a second determining unit.

[0121] The first determining unit is used to determine the symbol phase deviation value corresponding to each of the multiple high-quality intermediate pilot symbols based on the phase of each of the multiple high-quality intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the multiple high-quality intermediate pilot symbols.

[0122] The second determining unit is used to determine the first phase adjustment value corresponding to each intermediate OFDM symbol based on the phase deviation values ​​of multiple symbols.

[0123] According to an embodiment of this application, a second determining unit for determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on multiple symbol phase deviation values ​​includes a first determining subunit, a second determining subunit, a third determining subunit, and a fourth determining subunit.

[0124] The first determining sub-unit is used to determine the number of targets within the target phase deviation value range of multiple symbol phase deviation values.

[0125] The second determining subunit is used to correct multiple symbol phase deviation values ​​when the target number is greater than a preset number threshold, so as to obtain the corrected symbol phase deviation value corresponding to each of the multiple symbol phase deviation values.

[0126] The third determining subunit is used to determine the first phase adjustment value based on the phase deviation values ​​of multiple correction symbols.

[0127] The fourth determining subunit is used to determine the first phase adjustment value based on multiple symbol phase deviation values ​​when the target quantity is less than or equal to a preset quantity threshold.

[0128] According to an embodiment of this application, a second determining subunit for correcting multiple symbol phase deviation values ​​to obtain corrected symbol phase deviation values ​​corresponding to each of the multiple symbol phase deviation values ​​when the target number is greater than a preset number threshold includes a first determining component and a second determining component.

[0129] The first determining component is used to adjust the symbol phase deviation value according to the value range of the symbol phase deviation value when the target number is greater than a preset number threshold and the symbol phase deviation value is negative, so as to obtain the corrected symbol phase deviation value corresponding to each of the multiple symbol phase deviation values.

[0130] The second determining component is used to obtain the corrected symbol phase deviation value corresponding to each of the multiple symbol phase deviation values, based on the symbol phase deviation value, when the target number is greater than a preset number threshold and the symbol phase deviation value is not negative.

[0131] According to an embodiment of this application, a third obtaining module for adjusting the phase of an intermediate OFDM signal according to a first phase adjustment value corresponding to each intermediate OFDM symbol to obtain a target OFDM signal includes a first obtaining submodule and a second obtaining submodule.

[0132] The first submodule is used to fit the first phase adjustment value corresponding to each intermediate OFDM symbol to obtain the second frequency adjustment value and the second phase adjustment value.

[0133] The second submodule is used to adjust the intermediate OFDM signal according to the second frequency adjustment value and the second phase adjustment value to obtain the target OFDM signal.

[0134] According to an embodiment of this application, a first determining module 820 for determining a first frequency adjustment value based on the spectral line position of the higher-order spectrum of the master synchronization sequence includes a third determining submodule and a fourth determining submodule.

[0135] The third determining submodule is used to determine the first frequency adjustment value based on the center spectral line of the higher-order spectrum of the master synchronization sequence. And / or

[0136] The fourth determination submodule is used to determine the first frequency adjustment value based on the adjacent spectral lines of the center spectral line of the higher-order spectrum of the master synchronization sequence.

[0137] According to an embodiment of this application, a first obtaining module 810 for processing an initial OFDM signal to obtain a processed OFDM signal includes a third obtaining submodule, a fourth obtaining submodule, and a fifth obtaining submodule.

[0138] The third submodule is used to sample the initial OFDM signal based on the sampling signal to obtain the sampled OFDM signal.

[0139] The fourth submodule is used to perform coarse parameter estimation on the sampled OFDM signal to obtain the coarse parameter estimation result of the sampled OFDM signal. The coarse parameter estimation result includes at least one of the following: the signal start time, the signal end time, or the signal frequency range of the sampled OFDM signal.

[0140] The fifth submodule is used to preprocess the sampled OFDM signal based on the coarse parameter estimation results to obtain the processed OFDM signal.

[0141] According to embodiments of this application, preprocessing includes at least one of time slicing, zero-IF shifting, upsampling, or filtering.

[0142] The third obtaining submodule, which is used to preprocess the sampled OFDM signal based on the coarse parameter estimation results, to obtain the processed OFDM signal, includes a first obtaining unit, a second obtaining unit, a third obtaining unit, and a fourth obtaining unit.

[0143] The first obtaining unit is used to time-slice the sampled OFDM signal according to the signal start time and signal end time, so that the obtained processed OFDM signal is a signal within a preset time period. And / or the second obtaining unit is used to zero-IF shift the sampled OFDM signal according to the signal frequency range, so that the signal center frequency of the obtained processed OFDM signal is the target frequency. And / or the third obtaining unit is used to upsample the sampled OFDM signal according to the sampling frequency of the sampled signal and the initial frequency of the initial OFDM signal, so that the sampling frequency of the obtained processed OFDM signal is the target sampling frequency; and / or the fourth obtaining unit is used to filter the sampled OFDM signal according to the signal frequency range, so that the obtained processed OFDM signal is a signal within a preset frequency band.

[0144] Any one or more of the modules, submodules, units, and subunits according to the embodiments of this application, or at least part of the functions of any one or more of them, can be implemented in one module. Any one or more of the modules, submodules, units, and subunits according to the embodiments of this application can be implemented by dividing them into multiple modules. Any one or more of the modules, submodules, units, and subunits according to the embodiments of this application can be at least partially implemented as hardware circuits, such as field-programmable gate arrays (FPGAs), programmable logic arrays (PLAs), systems-on-a-chip, systems-on-a-substrate, systems-on-package, application-specific integrated circuits (ASICs), or implemented by hardware or firmware in any other reasonable manner by integrating or packaging circuits, or implemented in any one of software, hardware, and firmware, or in a suitable combination of any of these. Alternatively, one or more of the modules, submodules, units, and subunits according to the embodiments of this application can be at least partially implemented as computer program modules, which, when run, can perform corresponding functions.

[0145] For example, any plurality of the first obtaining module 810, the first determining module 820, the second obtaining module 830, the second determining module 840, and the third obtaining module 850 can be combined into one module / unit / subunit, or any one of these modules / units / subunits can be split into multiple modules / units / subunits. Alternatively, at least part of the functionality of one or more of these modules / units / subunits can be combined with at least part of the functionality of other modules / units / subunits and implemented in one module / unit / subunit. According to embodiments of this application, at least one of the first obtaining module 810, the first determining module 820, the second obtaining module 830, the second determining module 840, and the third obtaining module 850 can be at least partially implemented as hardware circuitry, such as a field-programmable gate array (FPGA), a programmable logic array (PLA), a system-on-a-chip, a system-on-a-substrate, a system-on-package, an application-specific integrated circuit (ASIC), or any other reasonable means of integrating or packaging the circuitry, or implemented in software, hardware, or firmware, or in any suitable combination of any of these three implementation methods. Alternatively, at least one of the first obtaining module 810, the first determining module 820, the second obtaining module 830, the second determining module 840, and the third obtaining module 850 may be at least partially implemented as a computer program module, which can perform corresponding functions when the computer program module is run.

[0146] Figure 9 A block diagram of an electronic device suitable for implementing the frequency offset processing method for OFDM signals described above, according to an embodiment of this application, is shown. Figure 9 The electronic device shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0147] like Figure 9 As shown, an electronic device 900 according to an embodiment of this application includes a processor 901, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 902 or a program loaded from a storage portion 908 into a random access memory (RAM) 903. The processor 901 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 901 may also include onboard memory for caching purposes. The processor 901 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of this application.

[0148] RAM 903 stores various programs and data required for the operation of electronic device 900. Processor 901, ROM 902, and RAM 903 are interconnected via bus 904. Processor 901 executes various operations of the method flow according to embodiments of this application by executing programs in ROM 902 and / or RAM 903. It should be noted that the programs may also be stored in one or more memories other than ROM 902 and RAM 903. Processor 901 may also execute various operations of the method flow according to embodiments of this application by executing programs stored in said one or more memories.

[0149] According to embodiments of this application, the electronic device 900 may further include an input / output (I / O) interface 905, which is also connected to a bus 904. The electronic device 900 may also include one or more of the following components connected to the input / output (I / O) interface 905: an input section 906 including a keyboard, mouse, etc.; an output section 907 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 908 including a hard disk, etc.; and a communication section 909 including a network interface card such as a LAN card, modem, etc. The communication section 909 performs communication processing via a network such as the Internet. A drive 910 is also connected to the input / output (I / O) interface 905 as needed. A removable medium 911, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 910 as needed so that computer programs read from it can be installed into the storage section 908 as needed.

[0150] According to embodiments of this application, the method flow according to embodiments of this application can be implemented as a computer software program. For example, embodiments of this application include a computer program product comprising a computer program carried on a computer-readable storage medium, the computer program containing program code for performing the methods shown in the flowchart. In such embodiments, the computer program can be downloaded and installed from a network via communication section 909, and / or installed from removable medium 911. When the computer program is executed by processor 901, it performs the functions defined in the system of embodiments of this application. According to embodiments of this application, the systems, devices, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0151] This application also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of this application.

[0152] According to embodiments of this application, the computer-readable storage medium can be a non-volatile computer-readable storage medium. Examples include, but are not limited to: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0153] For example, according to embodiments of this application, a computer-readable storage medium may include the ROM 902 and / or RAM 903 described above and / or one or more memories other than ROM 902 and RAM 903.

[0154] Embodiments of this application also include a computer program product comprising a computer program containing program code for performing the methods provided in the embodiments of this application. When the computer program product is run on an electronic device, the program code is used to enable the electronic device to implement the methods provided in the embodiments of this application.

[0155] When the computer program is executed by the processor 901, it performs the functions defined in the system / apparatus of this application embodiment. According to the embodiments of this application, the systems, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0156] In one embodiment, the computer program may rely on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may also be transmitted and distributed in the form of signals over a network medium, and downloaded and installed via the communication section 909, and / or installed from a removable medium 911. The program code contained in the computer program can be transmitted using any suitable network medium, including but not limited to: wireless, wired, etc., or any suitable combination thereof.

[0157] According to embodiments of this application, program code for executing the computer programs provided in the embodiments of this application can be written in any combination of one or more programming languages. Specifically, these computational programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, languages ​​such as Java, C++, Python, "C", or similar programming languages. The program code can be executed entirely on the user's computing device, partially on the user's device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0158] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions. Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations are not explicitly described in this application. In particular, without departing from the spirit and teachings of this application, the features described in the various embodiments of this application can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of this application.

[0159] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Without departing from the scope of this application, those skilled in the art can make various substitutions and modifications, all of which should fall within the scope of this application.

Claims

1. A method for frequency offset processing of OFDM signals, characterized in that, include: The initial OFDM signal is processed to obtain a processed OFDM signal, wherein the initial OFDM signal is a signal sent from the transmitting end to the receiving end, and the processed OFDM signal includes a master synchronization sequence and multiple OFDM symbols, each OFDM symbol including multiple pilot symbols; The first frequency adjustment value is determined based on the spectral line positions of the higher-order spectrum of the master synchronization sequence; The frequency of the processed OFDM signal is adjusted according to the first frequency adjustment value to obtain an intermediate OFDM signal. The intermediate OFDM signal includes an intermediate main synchronization sequence corresponding to the main synchronization sequence and intermediate OFDM symbols corresponding to each of the multiple OFDM symbols. Each intermediate OFDM symbol includes multiple intermediate pilot symbols. For each of the intermediate OFDM symbols: Based on the phases of the plurality of intermediate pilot symbols and the phases of the theoretical pilot symbols corresponding to the plurality of intermediate pilot symbols, a first phase adjustment value corresponding to each intermediate OFDM symbol is determined, wherein the theoretical pilot symbol indicates the theoretical transmission phase of the intermediate pilot symbol; The phase of the intermediate OFDM signal is adjusted according to a first phase adjustment value corresponding to each intermediate OFDM symbol to obtain a target OFDM signal, wherein the target OFDM signal includes a target OFDM symbol corresponding to each of the plurality of intermediate OFDM symbols.

2. The method according to claim 1, characterized in that, The step of determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on the phase of each of the plurality of intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the plurality of intermediate pilot symbols includes: Based on the symbol transmission quality of each of the intermediate pilot symbols, a plurality of high-quality intermediate pilot symbols are determined from the plurality of intermediate pilot symbols; Based on the phases of the various high-quality intermediate pilot symbols and the phases of the theoretical pilot symbols corresponding to the various high-quality intermediate pilot symbols, a first phase adjustment value corresponding to each intermediate OFDM symbol is determined.

3. The method according to claim 2, characterized in that, The step of determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on the phases of the plurality of high-quality intermediate pilot symbols and the phases of the theoretical pilot symbols corresponding to the plurality of high-quality intermediate pilot symbols includes: Based on the phase of each of the multiple high-quality intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the multiple high-quality intermediate pilot symbols, determine the symbol phase deviation value corresponding to each of the multiple high-quality intermediate pilot symbols. Based on the multiple symbol phase deviation values, a first phase adjustment value corresponding to each intermediate OFDM symbol is determined.

4. The method according to claim 3, characterized in that, The step of determining a first phase adjustment value corresponding to each intermediate OFDM symbol based on multiple symbol phase deviation values ​​includes: Determine the number of targets within the target phase deviation value range for the multiple symbol phase deviation values; When the target number is greater than a preset number threshold, the multiple symbol phase deviation values ​​are corrected to obtain corrected symbol phase deviation values ​​corresponding to each of the multiple symbol phase deviation values. The first phase adjustment value is determined based on the phase deviation values ​​of the multiple correction symbols; If the target number is less than or equal to the preset number threshold, the first phase adjustment value is determined based on the multiple symbol phase deviation values.

5. The method according to claim 4, characterized in that, When the target number is greater than a preset threshold, the step of correcting multiple symbol phase deviation values ​​to obtain corrected symbol phase deviation values ​​corresponding to each of the multiple symbol phase deviation values ​​includes: When the target number is greater than the preset number threshold and the symbol phase deviation value is negative, the symbol phase deviation value is adjusted according to the value range of the symbol phase deviation value to obtain the corrected symbol phase deviation value corresponding to each of the multiple symbol phase deviation values. When the target number is greater than the preset number threshold and the symbol phase deviation value is not negative, a corrected symbol phase deviation value corresponding to each of the multiple symbol phase deviation values ​​is obtained based on the symbol phase deviation value.

6. The method according to any one of claims 1 to 5, characterized in that, The step of adjusting the phase of the intermediate OFDM signal according to a first phase adjustment value corresponding to each intermediate OFDM symbol includes: The first phase adjustment value corresponding to each intermediate OFDM symbol is fitted to obtain the second frequency adjustment value and the second phase adjustment value. The intermediate OFDM signal is adjusted according to the second frequency adjustment value and the second phase adjustment value to obtain the target OFDM signal.

7. The method according to any one of claims 1 to 5, characterized in that, Determining the first frequency adjustment value based on the spectral line positions of the higher-order spectrum of the master synchronization sequence includes: The first frequency adjustment value is determined based on the center spectral line of the higher-order spectrum of the master synchronization sequence; and / or The first frequency adjustment value is determined based on the adjacent spectral lines of the center spectral line of the higher-order spectrum of the master synchronization sequence.

8. The method according to any one of claims 1 to 5, characterized in that, The process of processing the initial OFDM signal to obtain the processed OFDM signal includes: The initial OFDM signal is sampled according to the sampling signal to obtain the sampled OFDM signal; The sampled OFDM signal is subjected to coarse parameter estimation to obtain a coarse parameter estimation result of the sampled OFDM signal. The coarse parameter estimation result includes at least one of the signal start time, signal end time, or signal frequency range of the sampled OFDM signal. The sampled OFDM signal is preprocessed based on the coarse estimation results of the parameters to obtain the processed OFDM signal.

9. The method according to claim 8, characterized in that, The preprocessing includes at least one of time slicing, zero intermediate frequency shifting, upsampling, or filtering; The step of preprocessing the sampled OFDM signal based on the coarse parameter estimation result to obtain a processed OFDM signal includes: Based on the signal start time and signal end time, the sampled OFDM signal is time-sliced ​​so that the resulting processed OFDM signal is a signal within a preset time period; and / or Based on the signal frequency range, the sampled OFDM signal is zero-IF shifted so that the center frequency of the resulting processed OFDM signal is the target frequency; and / or Based on the sampling frequency of the sampled signal and the initial frequency of the initial OFDM signal, the sampled OFDM signal is upsampled so that the sampling frequency of the resulting processed OFDM signal is the target sampling frequency; and / or The sampled OFDM signal is filtered according to the signal frequency range so that the resulting processed OFDM signal is a signal within a preset frequency band.

10. A frequency offset processing device for OFDM signals, characterized in that, include: The first obtaining module is used to process the initial OFDM signal to obtain a processed OFDM signal, wherein the initial OFDM signal is a signal sent from the transmitting end to the receiving end, and the processed OFDM signal includes a master synchronization sequence and multiple OFDM symbols, each OFDM symbol including multiple pilot symbols; The first determining module is used to determine a first frequency adjustment value based on the spectral line positions of the higher-order spectrum of the master synchronization sequence; The second obtaining module is used to adjust the frequency of the processed OFDM signal according to the first frequency adjustment value to obtain an intermediate OFDM signal, wherein the intermediate OFDM signal includes an intermediate main synchronization sequence corresponding to the main synchronization sequence and intermediate OFDM symbols corresponding to each of the plurality of OFDM symbols, and each intermediate OFDM symbol includes a plurality of intermediate pilot symbols. The second determining module is configured to, for each intermediate OFDM symbol, determine a first phase adjustment value corresponding to each intermediate OFDM symbol based on the phase of each of the plurality of intermediate pilot symbols and the phase of the theoretical pilot symbol corresponding to each of the plurality of intermediate pilot symbols, wherein the theoretical pilot symbol indicates the theoretical transmission phase of the intermediate pilot symbol; The third obtaining module is used to adjust the phase of the intermediate OFDM signal according to the first phase adjustment value corresponding to each intermediate OFDM symbol to obtain the target OFDM signal, wherein the target OFDM signal includes the target OFDM symbol corresponding to each of the plurality of intermediate OFDM symbols.

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