Signal Synchronization Method and Device Based on OFDM System

Abstract

The embodiment of the present application relates to a signal synchronization method and device based on an OFDM system. The method performs autocorrelation calculation on a received wireless signal through a preset time interval and a preset window length. When the autocorrelation value corresponding to a sampling point at a certain moment is greater than a preset autocorrelation peak threshold, it is determined whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal, so that the false autocorrelation peak caused by noise and the real autocorrelation peak caused by a valid signal can be further distinguished, thereby avoiding the false synchronization phenomenon caused by noise and improving the accuracy and reliability of signal synchronization.

Description

Technical Field

[0001] The present invention relates to the field of electric power communication, and in particular to a signal synchronization method and device based on an OFDM system. Background Art

[0002] In power carrier communication, the transmitter of the orthogonal frequency division multiplexing (OFDM) system will decompose the transmission channel into several orthogonal sub-channels, convert the high-speed data signal to be transmitted into parallel low-speed data streams, and modulate them to the sub-carriers of each orthogonal channel for transmission. The superimposed and transmitted orthogonal signals are demodulated and separated in a certain way at the receiving end. In the OFDM communication system, it is crucial to ensure the accuracy of the time synchronization at the receiving end. Once the time synchronization deviates, on the one hand, the orthogonality between the sub-carriers will be destroyed, resulting in increased interference between the signals, thereby affecting the correct demodulation of the signal; at the same time, it may also lead to the erroneous reception of the entire data packet, resulting in data packet loss, which seriously affects the stability and reliability of communication.

[0003] The quality of power carrier communication is greatly affected by the environment, especially wireless communication, whose transmission environment is relatively complex. Factors such as the complexity of the signal path and channel changes increase the difficulty of data transmission. In wireless communication, the accuracy of time synchronization will be affected by various noise interferences, especially some regular noises, such as sine wave noise. Regular noise has a specific frequency, regular phase amplitude, etc., which can easily lead to the appearance of autocorrelation peaks in autocorrelation calculations. It is particularly obvious in the idle time when there is no effective signal transmission, resulting in the occurrence of missynchronization. Missynchronization will cause phase and frequency deviations in the signal demodulation process, making it impossible for the receiving end to accurately restore the original data, resulting in a decrease in communication quality. More seriously, missynchronization may also trigger a chain reaction, increase the amount of data processing, and lead to a series of errors in subsequent data processing, ultimately affecting the performance of the entire communication system. Therefore, how to improve the accuracy of synchronization and reduce the occurrence of missynchronization is an urgent problem to be solved. Summary of the invention

[0004] In view of this, in order to solve the problems in the background technology, the embodiments of the present application provide a signal frame synchronization method, device, readable storage medium and electronic device.

[0005] In a first aspect, an embodiment of the present application provides a signal synchronization method based on an OFDM system, the method comprising:

[0006] Receive wireless signals;

[0007] Based on a preset delay interval and a preset window length, performing autocorrelation calculation on the wireless signal to obtain an autocorrelation value corresponding to a sampling point at each moment;

[0008] If the autocorrelation value corresponding to a sampling point at a certain moment is greater than a preset autocorrelation peak threshold, it is determined whether the signal within the preset window length corresponding to the sampling point at that moment is a valid signal;

[0009] If the signal within the preset window length corresponding to the sampling point at the moment is a valid signal, the starting position of the signal frame in the wireless signal is obtained according to the sampling point at the moment.

[0010] In a second aspect, an embodiment of the present application provides a signal synchronization device based on an OFDM system, the device comprising:

[0011] A receiving unit, used for receiving wireless signals;

[0012] An autocorrelation value calculation unit, configured to perform autocorrelation calculation on the wireless signal based on a preset delay interval and a preset window length, and obtain an autocorrelation value corresponding to a sampling point at each moment;

[0013] A judgment unit, used to judge whether a signal within a preset window length corresponding to a sampling point at a certain moment is a valid signal if the autocorrelation value corresponding to the sampling point at the moment is greater than a preset autocorrelation peak threshold;

[0014] The starting position determining unit is used to obtain the starting position of the signal frame in the wireless signal according to the sampling point at the moment if the signal within the preset window length corresponding to the sampling point at the moment is a valid signal.

[0015] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, which stores instructions. When the instructions are executed by a processor of an electronic device, the electronic device can execute the signal synchronization method based on the OFDM system provided in any one of the above-mentioned first aspects.

[0016] In a fourth aspect, an embodiment of the present application provides an electronic device, the electronic device comprising:

[0017] processor;

[0018] memory for storing computer executable instructions;

[0019] The processor is used to execute the computer executable instructions to implement the signal synchronization method based on the OFDM system as described in any one of the first aspects above.

[0020] The embodiment of the present application performs autocorrelation calculation on the received wireless signal through a preset time interval and a preset window length. When the autocorrelation value corresponding to a sampling point at a certain moment is greater than a preset autocorrelation peak threshold, it is determined whether the signal within the preset window length corresponding to the sampling point at that moment is a valid signal, so that the false autocorrelation peak caused by noise and the real autocorrelation peak caused by a valid signal can be further distinguished, thereby avoiding the false synchronization phenomenon caused by noise and improving the accuracy and reliability of signal synchronization.

[0021] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0023] Figure 1 A schematic diagram of a flow chart of a signal synchronization method based on an OFDM system provided in one embodiment of the present application;

[0024] Figure 2 A flowchart of a method for autocorrelation calculation provided in one embodiment of the present application;

[0025] Figure 3 A schematic diagram of a flow chart of determining whether a time window signal is a valid signal according to an embodiment of the present application;

[0026] Figure 4 A schematic diagram of a signal synchronization device based on an OFDM system according to an embodiment of the present application;

[0027] Figure 5 A schematic diagram of the structure of an electronic device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the technical solutions and beneficial effects of the present invention more clearly understandable, the following is a detailed description by listing specific embodiments. In the present disclosure, it should be understood that terms such as "including" or "having" are intended to indicate the existence of the features, numbers, steps, behaviors, parts or combinations thereof disclosed in the present specification, and are not intended to exclude the possibility that one or more other features, numbers, steps, behaviors, parts or combinations thereof exist or are added.

[0029] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0030] The wireless signal synchronization method based on the OFDM system of the embodiment of the present application is used in the high-speed power line carrier communication (HPLC)-(high-speed wireless communication) HRF dual-mode system to improve the synchronization accuracy and reliability of the HRF signal. It should be noted that the HPLC-HRF dual-mode system uses power lines and space as transmission media to complement the advantages of wired and wireless. In the HPCL-HRF dual-mode system, HRF signal synchronization is achieved through short training sequence (STF) autocorrelation calculation, but due to interference, multipath, attenuation and other related characteristics in the power grid environment, the STF autocorrelation peak detection is more prone to misdetection, resulting in the occurrence of missynchronization.

[0031] Figure 1 FIG. 1 is a flow chart of a signal synchronization method based on an OFDM system according to an embodiment of the present application. Figure 1 As shown, the synchronization method provided in this embodiment includes the following steps:

[0032] S1. Receive wireless signals.

[0033] Specifically, the wireless signal includes a valid signal and a noise signal. The valid signal is the HRF signal sent by the transmitter. The HRF signal can be composed of one or more signal frames, each of which is composed of a preamble, a physical frame header control word (SIG), a physical frame header (PHR) and a physical layer service unit (PSDU); wherein the preamble includes an STF and a long training sequence (LTF), the STF is used for signal frame synchronization and coarse frequency synchronization, and the LTF is used for fine frequency synchronization and signal estimation. STF has a specific sequence structure, which is repeated or periodic in the time domain, so it can be identified by autocorrelation calculation; specifically, when a part of the signal is similar to other parts of itself, an autocorrelation peak can be obtained by autocorrelation calculation. Once the autocorrelation peak is found, the starting position of the signal frame can be determined. It should be noted that there is a frame interval between adjacent signal frames, and the signal in the frame interval is not a valid signal. The length of the frame interval is not fixed, but the transmitter changes according to the actual communication situation.

[0034] S2. Based on a preset delay interval and a preset window length, perform autocorrelation calculation on the wireless signal to obtain an autocorrelation value corresponding to a sampling point at each moment.

[0035] Among them, the preset delay interval and the preset window length are set according to the length of the STF in the communication protocol and the data format of the STF. Optionally, the preset delay interval is equal to the number of sampling point intervals of the repeated data segment in the STF, and the preset window length is equal to the length of the STF. For example, if each STF consists of 8 groups of repeated data, and each group of data has 10 sampling points, the preset delay interval is 10 sampling intervals, and the preset window length is 80 sampling points. It should be noted that each data frame may include one or more STFs, which is specifically related to the communication protocol and is not limited in this application.

[0036] Figure 2 A flow chart of a method for autocorrelation calculation provided in one embodiment of the present application. Figure 2 As shown, as an optional specific implementation, S2 includes:

[0037] S201. Obtain a first signal based on a preset window length and a sampling point at a current moment.

[0038] The first signal is a signal within a preset window length corresponding to the current sampling point. Specifically, sampling points are taken from the current sampling point forward in sequence until the length between the last sampling point and the current sampling point is equal to the preset window length.

[0039] S202: Based on a preset delay interval and according to a preset sampling rule, an autocorrelation calculation sequence corresponding to a sampling point at a current moment is obtained from the first signal.

[0040] The preset sampling rule is to select sampling points of preset delay intervals starting from the current sampling point. Specifically, for example, a first signal is {k1, k2, k3...k16}, where k16 is the current sampling point, and the preset delay interval is 4 sampling intervals, then the autocorrelation calculation sequence corresponding to the current sampling point is {k16, k12, k8, k4}.

[0041] S203: Calculate the autocorrelation value corresponding to the sampling point at the current moment according to the autocorrelation calculation sequence corresponding to the sampling point at the current moment.

[0042] Optionally, the autocorrelation value corresponding to the sampling point at the current moment is calculated using the following formula:

[0043]

[0044] in, represents the autocorrelation value of the sampling point at the current time t, n represents the nth sampling point corresponding to the current time t, represents the amplitude of the nth sampling point, m represents the preset delay interval; k is a constant determined according to the number of STF repetition data in the communication protocol.

[0045] Compared with power line carrier communication, the transmission environment of wireless carrier communication is relatively complex. Factors such as signal complexity and channel changes increase the difficulty of data transmission. The embodiment of the present application is based on the repeatability of data in the STF, and the autocorrelation algorithm can more easily and quickly determine the position of the signal. Furthermore, the traditional autocorrelation method is based on continuous signal sampling points for autocorrelation calculation, which is computationally intensive and time-consuming, and is prone to calculation errors due to noise interference. The autocorrelation calculation of the embodiment of the present application is based on the regularity of the STF data of the transmitted signal, and the autocorrelation calculation is performed through sampling of a preset time window and a preset delay interval, which not only reduces the amount of calculation, but also can more accurately identify repeated data in the signal, thereby improving the accuracy and reliability of synchronization.

[0046] S3. If the autocorrelation value corresponding to a sampling point at a certain moment is greater than a preset autocorrelation peak threshold, it is determined whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal.

[0047] Specifically, if the autocorrelation value corresponding to a sampling point at a certain moment is greater than a preset autocorrelation peak threshold, it indicates that the sampling point at the current moment is an autocorrelation peak. Correspondingly, the starting position of the signal frame can be obtained according to the sampling point at the current moment. In the prior art, noise signals can seriously affect the identification of autocorrelation peaks in valid signals, especially when there are some periodic regular noises such as sine waves, autocorrelation peaks may also exist in the noise signal, resulting in false synchronization, which seriously affects the accuracy of signal synchronization. For example, in an OFDM system, the transmitter usually needs a local oscillator to generate a carrier signal, which is modulated with the data signal to be sent and then sent to the power line. However, due to system design reasons or environmental factors, such as insufficient physical isolation of the local oscillator, circuit design defects or external electromagnetic interference, the signal of the local oscillator may leak to other parts of the system, especially to the output end of the transmitter, thereby generating regular sinusoidal noise at the transmitter. These sinusoidal noises are similar to the STF in the preamble, have a specific structure and a fixed length, and are also presented as periodic waveforms in the time domain. In the frequency domain, they are also multiple discrete frequency components. Therefore, when performing autocorrelation calculations, the autocorrelation value is easily greater than the autocorrelation threshold, that is, periodic noise is also prone to generate autocorrelation peaks. In the prior art, due to the existence of periodic noise, relying solely on the appearance of the autocorrelation peak to determine the starting position of the signal frame may cause missynchronization. In the embodiment of the present application, by judging whether the time window signal corresponding to the autocorrelation peak is a valid signal, it is possible to more accurately distinguish between the false autocorrelation peak caused by the periodic noise and the real autocorrelation peak caused by the valid signal, thereby avoiding the missynchronization phenomenon caused by the periodic noise and improving the accuracy and reliability of signal synchronization.

[0048] It should be noted that if there is sinusoidal noise in the idle phase without signal transmission, misidentifying the sinusoidal wave in the noise as a valid signal will lead to subsequent demodulation errors, and additional computing resources may be required for error detection and correction, thereby reducing the overall efficiency of the system; in extreme cases, missynchronization persists and cannot be resolved, which may cause the system to fail to work properly. If there is sinusoidal noise in the phase of signal transmission, since there will be frame intervals between signal frames, it is also easy to misidentify the useless signals between the frame intervals as valid signals, thereby introducing erroneous data in the subsequent demodulation process, affecting the communication performance of the system.

[0049] Figure 3 FIG. 1 is a flow chart of determining whether a time window signal is a valid signal according to an embodiment of the present application. Figure 3 As shown, as an optional specific implementation manner, determining whether a signal within a preset window length corresponding to the sampling point at the moment is a valid signal includes:

[0050] S301. Calculate phase differences between adjacent sampling points in a signal within a preset window length to obtain a first phase difference sequence.

[0051] Specifically, the time window signal corresponding to the autocorrelation peak includes information such as the count value, amplitude and phase of each sampling point, where the phase of the sampling point in the time window signal is , , ...... , where n represents the number of sampling points in the time window signal, Represents the phase of the nth sampling point. Specifically, the phase difference between adjacent sampling points is calculated by the following formula:

[0052]

[0053] in, Represents the phase difference between the n-1th adjacent points, represents the phase of the nth sampling point, Indicates the phase of the n-1th sampling point.

[0054] In the embodiment of the present application, the first phase difference sequence obtained according to the time window signal corresponding to the autocorrelation peak is: , , … For sinusoidal noise, the time interval between each sampling point is the same, and ideally the phase difference between adjacent sampling points is a fixed value, that is, = = =…… But the specific value is related to the sampling interval. It should be noted that the ideal sine wave signal is a periodic waveform, and the changes are consistent in each cycle. When sampled at a fixed time interval, the sine wave phase increases with the time sampling period. This increment is determined by the signal frequency and the sampling period. The higher the frequency, the faster the phase changes; the shorter the sampling period, the more obvious the phase difference between adjacent points; but no matter how it changes, the phase difference between adjacent points is always fixed.

[0055] S302: Calculate the differences between adjacent points in the first phase difference sequence to obtain a second phase difference sequence.

[0056] Specifically, the difference between adjacent points in the first phase difference sequence is calculated by the following formula:

[0057]

[0058] in, represents the difference value of the n-2th adjacent point in the first phase difference sequence. Correspondingly, the second phase difference sequence is , , … It should be noted that, for an ideal sinusoidal noise, the values ​​in the second phase difference sequence are all zero.

[0059] S303: Accumulate the values ​​in the second phase difference sequence to obtain a cumulative phase difference value.

[0060] Specifically, the cumulative phase difference is calculated by the following formula:

[0061]

[0062] in, Represents the cumulative phase difference. For ideal sinusoidal noise, its cumulative phase difference is zero. That is, in the time window signal, if it only contains ideal sinusoidal noise, its cumulative phase difference is zero; but in actual communication, when there is no idle phase in which effective signal transmission occurs, the noise includes sinusoidal noise and other noises, and its cumulative phase difference varies within a certain threshold range, and its cumulative phase difference is relatively small; when there is a phase in which effective signal transmission occurs, the time window signal will include effective signals, sinusoidal noise and other noises, and at this time its cumulative phase difference is mainly related to sinusoidal noise and effective signals, and its cumulative phase difference is the result of the superposition of the two, and its relative value is relatively large. It should be noted that the idle phase in which there is no effective signal transmission in the embodiment of the present application also includes the interval phase between signal frames during the effective signal transmission process, that is, it also includes the frame interval phase between signal frames.

[0063] S304: Compare the accumulated phase difference value with a preset effective threshold value, and determine whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal according to the comparison result.

[0064] Specifically, S304 includes: if the absolute value of the accumulated phase difference is less than the preset effective threshold, the signal within the preset window length corresponding to the sampling point at that moment is not a valid signal; if the absolute value of the accumulated phase difference is greater than the preset effective threshold, the signal within the preset window length corresponding to the sampling point at that moment is a valid signal.

[0065] In the embodiment of the present application, by comparing the accumulated phase difference value corresponding to the time window signal with the preset effective threshold, it is possible to determine whether the preset window length corresponding to the sampling point at that moment is a valid signal, thereby effectively avoiding the problem of missynchronization caused by sinusoidal wave noise and improving the synchronization accuracy and reliability of the OFDM system. It should be noted that the preset effective threshold can be set according to the actual communication situation.

[0066] As an optional specific implementation, a preset effective threshold is obtained according to a local reference sequence and a preset reference coefficient. Specifically, the preset effective threshold is calculated according to the following formula:

[0067] β=k'*λ

[0068] Wherein, β represents a preset effective threshold, k' represents a local cumulative phase difference value, and λ represents a preset reference coefficient. λ is less than 1, and the specific value is set according to the actual communication situation.

[0069] Optionally, the local cumulative phase difference value is calculated according to the local reference sequence, specifically including: calculating the phase difference of adjacent sampling points in the local reference sequence to obtain a first local phase difference sequence; calculating the difference between adjacent points in the first local phase difference sequence to obtain a second local phase difference sequence; accumulating the values ​​in the second local phase difference sequence to obtain a local cumulative phase difference value. It should be noted that the local reference sequence is data pre-stored at the receiving end, specifically, the local reference sequence is the STF in the preamble.

[0070] In the embodiment of the present application, although the local reference sequence has a certain regularity, the phase difference between its adjacent sampling points is not a fixed value. Therefore, the cumulative phase difference calculated by the sinusoidal noise and the local cumulative phase difference calculated by the local reference sequence will be significantly different. By using the local cumulative phase difference and the preset reference coefficient to obtain the preset effective threshold, it is possible to effectively determine whether the corresponding time window signal is a valid signal or a noise signal, thereby improving the accuracy and reliability of the judgment.

[0071] S4. If the signal within the preset window length corresponding to the sampling point at the moment is a valid signal, the starting position of the signal frame in the wireless signal is obtained according to the sampling point at the moment.

[0072] In one embodiment of the present application, the starting position of the frame signal in the received signal is determined by the autocorrelation peak, and then the received signal can be subsequently demodulated according to the starting position of the frame signal.

[0073] In the embodiment of the present application, by judging whether the signal within the preset window length corresponding to the autocorrelation peak is a valid signal, it is possible to accurately distinguish between the false autocorrelation peak caused by periodic noise and the true autocorrelation peak caused by the valid signal, thereby avoiding the false synchronization phenomenon caused by periodic noise and improving the accuracy and reliability of signal synchronization.

[0074] The signal frame synchronization method provided in the embodiment of the present application can be specifically applied in an electronic device, which may be a terminal, a server or other device.

[0075] It should be understood that although Figure 1-3 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1-3 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0076] Figure 4 FIG. 1 is a schematic diagram of a signal synchronization device based on an OFDM system according to an embodiment of the present application. Figure 4 As shown, the synchronization device includes:

[0077] The receiving unit 100 is used to receive a wireless signal;

[0078] An autocorrelation value calculation unit 200 is used to perform autocorrelation calculation on the wireless signal based on a preset delay interval and a preset window length to obtain an autocorrelation value corresponding to a sampling point at each moment;

[0079] The judging unit 300 is used to judge whether the signal within the preset window length corresponding to the sampling point at a certain moment is a valid signal if the autocorrelation value corresponding to the sampling point at the moment is greater than the preset autocorrelation peak threshold;

[0080] The starting position determining unit 400 is used to obtain the starting position of the signal frame in the wireless signal according to the sampling point at the moment if the signal within the preset window length corresponding to the sampling point at the moment is a valid signal.

[0081] Optionally, the judging unit 300 includes:

[0082] A first phase difference sequence calculation unit, used to calculate the phase differences of adjacent sampling points in a signal within a preset window length to obtain a first phase difference sequence;

[0083] A second phase difference sequence calculation unit, used to calculate the difference between adjacent points in the first phase difference sequence to obtain a second phase difference sequence;

[0084] A cumulative phase difference value calculation unit, used for accumulating the values ​​in the second phase difference sequence to obtain a cumulative phase difference value;

[0085] The comparison and judgment unit is used to compare the accumulated phase difference value with the preset effective threshold value, and judge whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal according to the comparison result.

[0086] Optionally, judging whether a signal within a preset window length corresponding to the sampling point at the moment is a valid signal according to the comparison result includes:

[0087] If the absolute value of the accumulated phase difference is less than the preset effective threshold, the signal within the preset window length corresponding to the sampling point at that moment is not a valid signal;

[0088] If the absolute value of the accumulated phase difference is greater than the preset effective threshold, the signal within the preset window length corresponding to the sampling point at that moment is a valid signal.

[0089] Optionally, a preset effective threshold is calculated based on a local reference sequence and a preset reference coefficient.

[0090] Optionally, the autocorrelation value calculation unit 200 includes:

[0091] A first signal acquisition unit, configured to acquire a first signal based on a preset window length and a sampling point at a current moment; wherein the first signal is a signal within the preset window length corresponding to the sampling point at the current moment;

[0092] An autocorrelation sequence sampling unit, configured to obtain an autocorrelation calculation sequence corresponding to a sampling point at a current moment from the first signal based on a preset delay interval and according to a preset sampling rule;

[0093] The sampling point autocorrelation calculation unit is used to calculate the autocorrelation value corresponding to the sampling point at the current moment according to the autocorrelation calculation sequence corresponding to the sampling point at the current moment.

[0094] Optionally, the autocorrelation value corresponding to the sampling point at the current moment is calculated using the following formula:

[0095]

[0096] in, represents the autocorrelation value of the sampling point at the current time t, n represents the nth sampling point corresponding to the current time t, represents the amplitude of the nth sampling point, m represents the preset delay interval; k is a constant determined according to the number of STF repetition data in the communication protocol.

[0097] The embodiment of the present application further provides a computer-readable storage medium. The computer-readable storage medium stores instructions, and when the instructions are executed by a processor of an electronic device, the electronic device can execute the steps of the signal synchronization method based on an OFDM system in any of the above embodiments.

[0098] The embodiments of the present application may be systems, methods and / or computer program products. The computer program product may include a computer-readable storage medium on which computer-readable program instructions are loaded for causing a processor to implement various aspects of the present application. In some embodiments, by using the state information of the computer-readable program instructions to personalize an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA) or a programmable logic array (PLA), the electronic circuit may execute the computer-readable program instructions to implement various aspects of the present application.

[0099] Computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. Computer readable storage medium is a tangible device that can keep and store instructions used by an instruction execution device. The readable storage medium can include, for example, but is not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage medium include: portable computer disk, hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disk read-only memory (CD-ROM), digital versatile disk (DVD), memory stick, floppy disk, mechanical encoding device, such as a punch card or a protruding structure in a groove on which instructions are stored, and any suitable combination of the above.

[0100] Various aspects of the present application are described herein with reference to flowcharts and / or block diagrams of methods, devices (systems) and computer program products according to embodiments of the present application. It should be understood that each box in the flowchart and / or block diagram and the combination of boxes in the flowchart and / or block diagram can be implemented by computer-readable program instructions.

[0101] An embodiment of the present application also provides an electronic device. Figure 5 This is a schematic diagram of the structure of an electronic device provided by an embodiment of the present application. Figure 5 As shown, the electronic device 500 includes: one or more processors 501 and a memory 502; the memory 502 stores computer executable instructions; the processor 501 is used to execute the computer executable instructions to implement the steps in the signal synchronization method based on the OFDM system as in any of the above embodiments.

[0102] The processor 501 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0103] The memory 502 may include one or more computer program products, and the computer program products may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory (cache), etc. Non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 501 may execute the program instructions to implement the steps in the text recognition method of each embodiment of the present application described above and / or other desired functions.

[0104] In one example, the electronic device 500 may further include: an input device and an output device, and these components are interconnected via a bus system and / or other forms of connection mechanisms (not shown in the figure).

[0105] In addition, the input device may also include, for example, a keyboard, a mouse, a microphone, etc. The output device may output various information to the outside, and may include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto, and the like.

[0106] Of course, to simplify, Figure 5 Only a part of the components related to the present application in the electronic device 500 is shown, and components such as a bus, an input device / output interface, etc. are omitted. In addition, according to specific application conditions, the electronic device 500 may also include any other appropriate components.

[0107] It should be noted that the signal synchronization method embodiment based on OFDM system, the signal synchronization device embodiment based on OFDM system, the computer-readable storage medium embodiment and the electronic device embodiment provided in the embodiments of the present application belong to the same concept; the technical features in the technical solutions recorded in each embodiment can be arbitrarily combined without conflict.

[0108] It should be understood that the above embodiments are exemplary and are not intended to include all possible implementations included in the claims. Various modifications and changes may be made on the basis of the above embodiments without departing from the scope of the present disclosure. Similarly, the various technical features of the above embodiments may be arbitrarily combined to form other embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only express several implementations of the present invention and do not limit the scope of protection of the patent of the present invention.

Claims

1. A signal synchronization method based on an OFDM system, characterized in that: The method comprises: Receive wireless signals; Based on a preset delay interval and a preset window length, an autocorrelation calculation is performed on the wireless signal to obtain an autocorrelation value corresponding to a sampling point at each moment; wherein the preset window length is equal to the length of a short training sequence (STF); and the preset delay interval is equal to the number of sampling point intervals of a repeated data segment in the STF; If the autocorrelation value corresponding to a sampling point at a certain moment is greater than a preset autocorrelation peak threshold, it is determined whether the signal within the preset window length corresponding to the sampling point at that moment is a valid signal; If the signal within the preset window length corresponding to the sampling point at the moment is a valid signal, then obtaining the starting position of the signal frame in the wireless signal according to the sampling point at the moment; Among them, the autocorrelation value corresponding to each sampling point at each moment is calculated by the following formula: ， in, represents the autocorrelation value of the sampling point at the current time t, n represents the nth sampling point corresponding to the current time t, represents the amplitude of the nth sampling point, m represents the preset delay interval; k is a constant determined according to the number of STF repetition data in the communication protocol; Wherein, judging whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal includes: Calculating phase differences between adjacent sampling points in the signal within the preset window length to obtain a first phase difference sequence; Calculating the differences between adjacent points in the first phase difference sequence to obtain a second phase difference sequence; Accumulating the values ​​in the second phase difference sequence to obtain a cumulative phase difference value; Compare the accumulated phase difference value with the preset effective threshold value, and determine whether the signal within the preset window length corresponding to the sampling point at that moment is a valid signal based on the comparison result.

2. The signal synchronization method based on OFDM system as claimed in claim 1, characterized in that: Judging whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal according to the comparison result includes: If the absolute value of the accumulated phase difference is less than the preset effective threshold, the signal within the preset window length corresponding to the sampling point at this moment is not a valid signal; If the absolute value of the accumulated phase difference is greater than the preset validity threshold, the signal within the preset window length corresponding to the sampling point at this moment is a valid signal.

3. The signal synchronization method based on OFDM system as claimed in claim 1, characterized in that: The preset effective threshold is obtained according to the local reference sequence and the preset reference coefficient.

4. The signal synchronization method based on OFDM system as claimed in claim 3, characterized in that: The preset effective threshold is calculated by the following formula: β=k'*λ Wherein, β represents a preset effective threshold, k' represents a local accumulated phase difference value, and λ represents a preset reference coefficient; The local accumulated phase difference value is calculated by the local reference sequence, specifically including: Calculate the phase differences of adjacent sampling points in the local reference sequence to obtain a first local phase difference sequence; Calculating differences between adjacent points in the first local phase difference sequence to obtain a second local phase difference sequence; The values ​​in the second local phase difference sequence are accumulated to obtain a local accumulated phase difference value.

5. The signal synchronization method based on OFDM system as claimed in claim 1, characterized in that: Based on a preset delay interval and a preset window length, performing autocorrelation calculation on the wireless signal to obtain an autocorrelation value corresponding to a sampling point at each moment, including: Based on the preset window length and the current sampling point, a first signal is obtained; wherein the first signal is a signal within the preset window length corresponding to the current sampling point; Based on a preset delay interval, obtaining an autocorrelation calculation sequence corresponding to the sampling point at the current moment from the first signal according to a preset sampling rule; According to the autocorrelation calculation sequence corresponding to the sampling point at the current moment, the autocorrelation value corresponding to the sampling point at the current moment is calculated.

6. A signal synchronization device based on an OFDM system, characterized in that: The device comprises: A receiving unit, used for receiving wireless signals; An autocorrelation value calculation unit, configured to perform autocorrelation calculation on the wireless signal based on a preset delay interval and a preset window length, to obtain an autocorrelation value corresponding to a sampling point at each moment; wherein the preset window length is equal to the length of the STF; and the preset delay interval is equal to the number of sampling point intervals of a repeated data segment in the STF; A judgment unit, used to judge whether a signal within a preset window length corresponding to a sampling point at a certain moment is a valid signal if the autocorrelation value corresponding to the sampling point at the moment is greater than a preset autocorrelation peak threshold; A starting position determining unit, configured to obtain a starting position of a signal frame in the wireless signal according to the sampling point at the moment if the signal within a preset window length corresponding to the sampling point at the moment is a valid signal; Among them, the autocorrelation value corresponding to each sampling point at each moment is calculated by the following formula: ， in, represents the autocorrelation value of the sampling point at the current time t, n represents the nth sampling point corresponding to the current time t, represents the amplitude of the nth sampling point, m represents the preset delay interval; k is a constant determined according to the number of STF repetition data in the communication protocol; The judging unit includes: A first phase difference sequence calculation unit, used to calculate the phase differences of adjacent sampling points in the signal within the preset window length to obtain a first phase difference sequence; A second phase difference sequence calculation unit, configured to calculate the difference between adjacent points in the first phase difference sequence to obtain a second phase difference sequence; A cumulative phase difference value calculation unit, used for accumulating the values ​​in the second phase difference sequence to obtain a cumulative phase difference value; The comparison and judgment unit is used to compare the accumulated phase difference value with the preset effective threshold value, and judge whether the signal within the preset window length corresponding to the sampling point at this moment is a valid signal according to the comparison result.

7. The signal synchronization device based on OFDM system as claimed in claim 6, characterized in that: Judging whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal according to the comparison result includes: If the absolute value of the accumulated phase difference is less than the preset effective threshold, the signal within the preset window length corresponding to the sampling point at this moment is not a valid signal; If the absolute value of the accumulated phase difference is greater than the preset validity threshold, the signal within the preset window length corresponding to the sampling point at this moment is a valid signal.

8. The signal synchronization device based on OFDM system as claimed in claim 6, characterized in that: The preset effective threshold is obtained according to the local reference sequence and the preset reference coefficient.

9. The signal synchronization device based on OFDM system as claimed in claim 8, characterized in that: The preset effective threshold is calculated by the following formula: β=k'*λ; Wherein, β represents a preset effective threshold, k' represents a local accumulated phase difference value, and λ represents a preset reference coefficient; The local accumulated phase difference value is calculated by the local reference sequence, specifically including: Calculate the phase differences of adjacent sampling points in the local reference sequence to obtain a first local phase difference sequence; Calculating differences between adjacent points in the first local phase difference sequence to obtain a second local phase difference sequence; The values ​​in the second local phase difference sequence are accumulated to obtain a local accumulated phase difference value.

10. The signal synchronization device based on OFDM system as claimed in claim 6, characterized in that: The autocorrelation value calculation unit comprises: A first signal acquisition unit, configured to acquire a first signal based on a preset window length and a sampling point at a current moment; wherein the first signal is a signal within the preset window length corresponding to the sampling point at the current moment; An autocorrelation sequence sampling unit, configured to obtain an autocorrelation calculation sequence corresponding to the sampling point at the current moment from the first signal based on a preset delay interval and according to a preset sampling rule; The sampling point autocorrelation calculation unit is used to calculate the autocorrelation value corresponding to the sampling point at the current moment according to the autocorrelation calculation sequence corresponding to the sampling point at the current moment.

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