Power line carrier signal synchronization method and device based on OFDMA system

Abstract

The invention discloses a power line carrier signal synchronization method and device based on an OFDMA system, and belongs to the technical field of power line carrier communication. The method comprises the following steps: performing cross-correlation processing on a received signal and a reference sequence to obtain a target cross-correlation result, and performing self-correlation operation on the target cross-correlation result and a target historical cross-correlation result to obtain a target self-correlation result; analyzing the position of a first target autocorrelation peak in the received signal based on the target autocorrelation result; the first target autocorrelation peak is the autocorrelation peak with the maximum peak value in the received signal; determining a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak; and determining the position of a synchronization peak in the received signal based on the position of the autocorrelation peak in the first window. According to the invention, the autocorrelation peak is determined by combining cross-correlation and autocorrelation, and the position of the synchronization peak is determined by integrating the position of the autocorrelation peak in the first window, so that the accuracy of signal synchronization is improved.

Description

Technical Field

[0001] This application belongs to the field of communication technologies, and particularly relates to a power line carrier signal synchronization method and apparatus based on an OFDMA system. Background Art

[0002] Orthogonal Frequency Division Multiple Access (OFDMA) is an advanced wireless communication access technology. It combines Orthogonal Frequency Division Multiple (OFDM) technology with multiple access, divides the available frequency band into multiple orthogonal subcarriers, and assigns different subcarriers to different users, thereby achieving parallel communication of multiple users.

[0003] However, in an actual communication environment, the signal will pass through multiple different paths to reach the receiving end during transmission. The lengths of these paths are different, and the attenuation degree and propagation delay of the signal on different paths will also be different, resulting in the received signal at the receiving end being a superposition of multiple attenuated and time-delayed signals, causing the position of the maximum peak of the received signal to deviate from the true synchronization peak position, and affecting the accuracy of signal synchronization. Summary of the Invention

[0004] This application aims to solve at least one of the technical problems existing in the prior art. For this purpose, this application proposes a power line carrier signal synchronization method and apparatus based on an OFDMA system to improve the accuracy of signal synchronization.

[0005] In a first aspect, this application provides a power line carrier signal synchronization method based on an OFDMA system, including: Performing cross-correlation processing on a received signal and a reference sequence to obtain a target cross-correlation result, and performing autocorrelation operation on the target cross-correlation result and a target historical cross-correlation result to obtain a target autocorrelation result; Analyzing the position of a first target autocorrelation peak in the received signal based on the target autocorrelation result; the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the received signal; Determining a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak; Determining the synchronization peak position in the received signal based on the positions of the autocorrelation peaks within the first window.

[0006] The power line carrier signal synchronization method based on the OFDMA system provided by the embodiment of the present application analyzes and processes the received signal and the reference sequence, combines the cross-correlation and auto-correlation methods, can capture the signal characteristics more comprehensively, improves the accuracy of auto-correlation peak detection. Since the first target auto-correlation peak is the auto-correlation peak with the largest peak value in the received signal, a first window is determined through the position of the first target auto-correlation peak, narrowing the analysis range of signal synchronization, and comprehensively determining the starting position of the data frame in the received signal based on the positions of the auto-correlation peaks within the first window, thereby reducing the synchronization error caused by the deviation of the maximum peak position from the true synchronization point and improving the accuracy of signal synchronization.

[0007] According to an embodiment of the present application, determining the synchronization peak position in the received signal based on the positions of the auto-correlation peaks within the first window includes: Judging whether the first target auto-correlation peak is a valid peak based on the signal-to-noise ratio of the first window; When the first target auto-correlation peak is a valid peak, determining the synchronization peak position in the received signal based on the positions of the auto-correlation peaks within the first window.

[0008] In this embodiment, considering that in the OFDMA system, multiple users will cause time delay, resulting in multipath effects, and the auto-correlation results during synchronization will have peaks with different energies within a certain range. At the same time, the influence of superimposed noise is considered, and the maximum auto-correlation peak is not necessarily a valid auto-correlation peak. By detecting the signal-to-noise ratio of the first window during synchronization, the signal quality can be accurately identified, and thus it can be accurately judged whether the first target auto-correlation peak is a valid peak.

[0009] According to an embodiment of the present application, judging whether the first target auto-correlation peak is a valid peak based on the signal-to-noise ratio of the received signal within the first window includes: Calculating the signal-to-noise ratio of the first window; When the signal-to-noise ratio is greater than the target signal-to-noise ratio threshold, determining that the first target auto-correlation peak is a valid peak.

[0010] In this embodiment, considering that the influence of multipath effects superimposed on the noise energy on the peak value of the auto-correlation peak is relatively large, by detecting the signal-to-noise ratio of the first window during synchronization, when the signal-to-noise ratio is higher than the target signal-to-noise ratio threshold, it indicates that the signal quality is good and the first target auto-correlation peak is a valid auto-correlation peak, thereby reducing the influence of noise and improving the accuracy of signal synchronization.

[0011] According to an embodiment of the present application, calculating the signal-to-noise ratio of the first window includes: Searching for a second window with a second target length based on the position of the first target auto-correlation peak; no auto-correlation peak is included within the second window; Determine the average value of the autocorrelation results of the sampling points of the received signal within the second window as the average noise energy within the second window; Take the average noise energy within the second window as the average noise energy within the first window, and combine it with the autocorrelation results of the sampling points of the received signal within the first window to calculate the average signal energy without noise within the first window; Determine the ratio of the average signal energy to the average noise energy as the signal-to-noise ratio.

[0012] According to an embodiment of the present application, according to the formula: , Calculate the average signal energy; Wherein, represents the average signal energy of the signal without noise within the first window, represents the autocorrelation result of the sampling point within the first window, represents the number of sampling points within the first window, represents the average noise energy within the second window.

[0013] In this embodiment, considering that the superposition of noise energy and multipath effects has a greater impact on the autocorrelation peak, by searching for a second window without an autocorrelation peak according to the position of the first target autocorrelation peak, since the second window does not include an autocorrelation peak, it can be considered that the received signal within the second window is mainly composed of noise. Taking the average noise energy within the second window as the average noise energy within the first window can reduce the influence of noise energy and make the calculation of the signal-to-noise ratio more accurate.

[0014] According to an embodiment of the present application, determining the first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak includes: Determine the first target length of the first window; Determine the range with the position of the target autocorrelation peak as the center and the length of the first target length as the first window.

[0015] In this embodiment, by clarifying the first target length of the first window and defining the window range with the position of the target autocorrelation peak as the center, it is possible to focus on the key feature area of the signal, reduce misjudgment caused by noise or interference in a complex signal environment, make better use of the autocorrelation characteristics of the signal, accurately locate the position of the synchronization peak, and improve the accuracy of signal synchronization.

[0016] According to an embodiment of the present application, determining the position of the synchronization peak in the received signal based on the position of the autocorrelation peak within the first window includes: Obtain multiple second target autocorrelation peaks within the first window; the multiple second target autocorrelation peaks at least include the first target autocorrelation peak; Determine the position of the synchronization peak in the received signal according to the positions of the multiple second target autocorrelation peaks.

[0017] In this embodiment, by comprehensively considering the position information of multiple autocorrelation peaks, the characteristics of the signal can be captured more comprehensively, reducing the synchronization error caused by the deviation of the maximum peak position from the true synchronization point and improving the accuracy of signal synchronization.

[0018] According to an embodiment of the present application, the second target autocorrelation peak is an autocorrelation peak whose peak value meets the target requirements among the autocorrelation peaks within the first window.

[0019] In this embodiment, by using the autocorrelation peak whose peak value meets the target requirements as a reference to determine the position of the synchronization peak in the received signal, the positions of multiple key peaks related to the synchronization peak position are integrated, which can reduce the overall deviation of the synchronization position and improve the accuracy of signal synchronization.

[0020] According to an embodiment of the present application, the target requirements include: the n autocorrelation peaks with the largest peak values among the autocorrelation peaks within the first window or the autocorrelation peaks whose peak values are greater than the target threshold among the autocorrelation peaks within the first window.

[0021] In this embodiment, by selecting the n autocorrelation peaks with the largest peak values, the autocorrelation characteristics of the signal can be fully utilized, or by setting the target threshold, some false peaks caused by noise can be excluded, and multiple key peaks related to the synchronization peak position can be screened out from the autocorrelation peaks within the first window, improving the accuracy of signal synchronization.

[0022] According to an embodiment of the present application, the determining the position of the synchronization peak in the received signal according to the positions of the multiple second target autocorrelation peaks includes: Calculate the average value or weighted average value of the positions of the multiple second target autocorrelation peaks; Determine the average value or the weighted average value as the position of the synchronization peak in the received signal.

[0023] In this embodiment, by comprehensively considering the position information of multiple autocorrelation peaks and adopting the method of average value or weighted average value, the synchronization deviation caused by the error of a single autocorrelation peak or the influence of noise can be reduced. Introducing the weighted average value can assign different weights according to the intensity or other characteristics of the autocorrelation peak, so as to more accurately locate the position of the synchronization peak.

[0024] According to an embodiment of the present application, the determining the average value or weighted average value of the positions of the multiple second target autocorrelation peaks includes: Determine the sampling points corresponding to multiple second target autocorrelation peaks; Take the positions of the sampling points corresponding to multiple second target autocorrelation peaks as the positions of multiple second target autocorrelation peaks, and determine the average value or the weighted average value.

[0025] In this embodiment, by using the sampling point positions to identify the positions of autocorrelation peaks and calculating the average value or weighted average value based on the positions of these sampling points, the position of the synchronization peak can be accurately located.

[0026] According to an embodiment of the present application, the cross-correlating the received signal with the reference sequence to obtain a target cross-correlation result, and performing an autocorrelation operation on the target cross-correlation result and the target historical cross-correlation result to obtain a target autocorrelation result includes: Perform a cross-correlation calculation on the signal sequence within the current sliding window in the received signal and the reference sequence to obtain a target cross-correlation result; the target cross-correlation result is the cross-correlation result of the first sampling point; the first sampling point is within the signal sequence in the current sliding window; Perform an autocorrelation calculation on the target cross-correlation result and the target historical cross-correlation result to obtain the target autocorrelation result; the target autocorrelation result is the autocorrelation result of the first sampling point; the target historical cross-correlation result is the cross-correlation result of the second sampling point, and the second sampling point is within the signal sequence in the historical sliding window.

[0027] In this embodiment, by performing a cross-correlation calculation to compare the signal sequence within the current sliding window in the received signal with the reference sequence, the similarity between the signal sequence and the reference sequence can be identified. Performing an autocorrelation calculation on the cross-correlation result of the first sampling point obtained and the cross-correlation result of the second sampling point in the historical sliding window to obtain the autocorrelation result of the first sampling point combines the cross-correlation and autocorrelation methods, can more comprehensively capture the characteristics of the signal, and improve the accuracy of autocorrelation peak detection.

[0028] According to an embodiment of the present application, the performing a cross-correlation calculation on the signal sequence within the current sliding window in the received signal and the reference sequence to obtain a target cross-correlation result includes: Calculate the symbol coefficient corresponding to each sampling point according to the signal amplitude corresponding to each sampling point in the signal sequence within the current sliding window; wherein, the positive and negative of the signal amplitude are the same as the positive and negative of the symbol coefficient; Multiply the symbol coefficients corresponding to the sampling points in the same position in the signal sequence within the current sliding window and the reference sequence, and sum the multiplication results of each sampling point to obtain a target cross-correlation result.

[0029] In this embodiment, by determining the sign coefficient of each sampling point according to the signal amplitude corresponding to each sampling point in the current sliding window signal sequence, the positive and negative of the signal amplitude are kept consistent with the positive and negative of the sign coefficient, so that complex multiplication operations are not required in the cross-correlation calculation, simplifying the calculation process and reducing the computational complexity.

[0030] According to an embodiment of the present application, the performing autocorrelation calculation on the target cross-correlation result and the target historical cross-correlation result to obtain the target autocorrelation result includes: Multiplying the cross-correlation result of the first sampling point by the cross-correlation result of the second sampling point to obtain the target autocorrelation result.

[0031] In this embodiment, by multiplying the cross-correlation result of the first sampling point by the cross-correlation result of the second sampling point, the autocorrelation result of the first sampling point is directly obtained, which can efficiently capture the internal correlation of the signal and simplifies the solution process of the autocorrelation result.

[0032] According to an embodiment of the present application, the analyzing the position of the first target autocorrelation peak in the received signal based on the target autocorrelation result includes: When the absolute value of the target autocorrelation result is greater than the target threshold, updating the target threshold with the absolute value of the target autocorrelation result; Searching for the autocorrelation results of the sampling points after the first sampling point. When the absolute value of the autocorrelation result of the sampling points after the first sampling point is greater than the updated target threshold, updating the target threshold with the absolute value of the autocorrelation result of the sampling points after the first sampling point until the absolute values of the autocorrelation results of the target number of sampling points are less than or equal to the updated target threshold; Determining the position of the first target autocorrelation peak according to the position of the target sampling point corresponding to the updated target threshold.

[0033] In this embodiment, when the absolute value of the autocorrelation result of the first sampling point is greater than the target threshold, it indicates that a position with a relatively large correlation is detected. Since the correlation peak has an ascending process, by comparing the autocorrelation results corresponding to several sampling points after the first sampling point in the received signal, finding the maximum value, and determining the position of the target sampling point corresponding to the maximum value as the position of the autocorrelation peak, the accuracy of determining the autocorrelation peak is improved.

[0034] In a second aspect, the present application provides a power line carrier signal synchronization device based on an OFDMA system. The device includes: A processing module, configured to perform cross-correlation processing on a received signal and a reference sequence to obtain a target cross-correlation result, and perform autocorrelation operation on the target cross-correlation result and a target historical cross-correlation result to obtain a target autocorrelation result; An analysis module, configured to analyze the position of a first target autocorrelation peak in the received signal based on the target autocorrelation result; the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the received signal; A first determination module, configured to determine a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak; A second determination module, configured to determine the position of a synchronization peak in the received signal based on the positions of the autocorrelation peaks within the first window.

[0035] The power line carrier signal synchronization device based on the OFDMA system provided by the embodiments of the present application analyzes and processes the received signal and the reference sequence through cross-correlation calculation, combines the methods of cross-correlation and autocorrelation, can capture the characteristics of the signal more comprehensively, improves the accuracy of autocorrelation peak detection. Since the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the received signal, the first window is determined according to the position of the first target autocorrelation peak, narrowing the analysis range of signal synchronization, and comprehensively determining the starting position of the data frame in the received signal based on the positions of the autocorrelation peaks within the first window, thereby reducing the synchronization error caused by the deviation of the position of the maximum peak from the true synchronization point and improving the accuracy of signal synchronization.

[0036] In a third aspect, the present application provides a power line carrier signal synchronization system based on an OFDMA system, including: A signal sending device, configured to send a signal; A signal receiving device, configured to execute the power line carrier signal synchronization method based on the OFDMA system as described in the first aspect above.

[0037] In a fourth aspect, the present application provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, where when the processor executes the computer program, it implements the power line carrier signal synchronization method based on the OFDMA system as described in the first aspect above.

[0038] In a fifth aspect, the present application provides a non-transitory computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the power line carrier signal synchronization method based on the OFDMA system as described in the first aspect above.

[0039] In a sixth aspect, the present application provides a computer program product, including a computer program which, when executed by a processor, implements the power line carrier signal synchronization method based on an OFDMA system as described in the first aspect above.

[0040] One or more of the above technical solutions in the embodiments of the present application have at least one of the following technical effects: The power line carrier signal synchronization method based on an OFDMA system provided by the embodiments of the present application analyzes and processes the received signal and a reference sequence, combines the methods of cross-correlation and auto-correlation, can capture the characteristics of the signal more comprehensively, improves the accuracy of auto-correlation peak detection. Since the first target auto-correlation peak is the auto-correlation peak with the largest peak value in the received signal, a first window is determined through the position of the first target auto-correlation peak, narrowing the analysis range of signal synchronization, and determining the starting position of the data frame in the received signal by synthesizing the positions of the auto-correlation peaks within the first window, thereby reducing the synchronization error caused by the deviation of the maximum peak position from the true synchronization point and improving the accuracy of signal synchronization.

[0041] Furthermore, considering that in an OFDMA system, multiple users will cause time delay, resulting in multipath effects, and the auto-correlation results during synchronization will have peaks with different energies within a certain range, and with the influence of superimposed noise, the maximum auto-correlation peak is not necessarily a valid auto-correlation peak. By detecting the signal-to-noise ratio of the first window during the synchronization process, the signal quality can be accurately identified, and thus it can be accurately determined whether the first target auto-correlation peak is a valid peak.

[0042] Furthermore, considering that the influence of the superimposed noise energy of multipath effects on the peak value of the auto-correlation peak is relatively large, by detecting the signal-to-noise ratio of the first window during the synchronization process, when the signal-to-noise ratio is higher than the target signal-to-noise ratio threshold, it indicates that the signal quality is good, and the first target auto-correlation peak is a valid auto-correlation peak, thereby reducing the influence of noise and improving the accuracy of signal synchronization.

[0043] Furthermore, considering that the influence of the superimposed noise energy of multipath effects on the auto-correlation peak is relatively large, by searching for a second window that does not include auto-correlation peaks according to the position of the first target auto-correlation peak, since the second window does not include auto-correlation peaks, it can be considered that the received signal within the second window is mainly composed of noise. Using the average noise energy within the second window as the average noise energy within the first window can reduce the influence of noise energy and make the calculation of the signal-to-noise ratio more accurate.

[0044] Furthermore, by defining the first target length of the first window and centering the window range on the position of the target autocorrelation peak, the key feature region of the signal can be focused, reducing misjudgment caused by noise or interference in a complex signal environment, better utilizing the autocorrelation characteristics of the signal, accurately locating the position of the synchronization peak, and improving the accuracy of signal synchronization.

[0045] Even further, by comprehensively considering the position information of multiple autocorrelation peaks, the characteristics of the signal can be captured more comprehensively, reducing the synchronization error caused by the deviation of the maximum peak position from the true synchronization point, and improving the accuracy of signal synchronization.

[0046] Even further, by using the autocorrelation peak whose peak value meets the target requirements as a reference to determine the position of the synchronization peak in the received signal, integrating the positions of multiple key peaks related to the synchronization peak position, the overall deviation of the synchronization position can be reduced, and the accuracy of signal synchronization can be improved.

[0047] Even further, by selecting the n autocorrelation peaks with the largest peak values, the autocorrelation characteristics of the signal can be fully utilized, or by setting a target threshold, some false peaks caused by noise can be excluded, and multiple key peaks related to the synchronization peak position can be screened out from the autocorrelation peaks of the first window, improving the accuracy of signal synchronization.

[0048] Even further, by comprehensively considering the position information of multiple autocorrelation peaks and using the method of average value or weighted average value, the synchronization deviation caused by the error or noise influence of a single autocorrelation peak can be reduced. Introducing the weighted average value can assign different weights according to the intensity or other characteristics of the autocorrelation peak, thereby more accurately locating the position of the synchronization peak.

[0049] Even further, by performing cross-correlation calculation to compare the signal sequence within the current sliding window in the received signal with the reference sequence, the similarity between the signal sequence and the reference sequence can be identified. Performing autocorrelation calculation on the cross-correlation result of the first sampling point and the cross-correlation result of the second sampling point within the historical sliding window to obtain the autocorrelation result of the first sampling point. Combining the methods of cross-correlation and autocorrelation can capture the characteristics of the signal more comprehensively and improve the accuracy of autocorrelation peak detection.

[0050] Even further, when the absolute value of the autocorrelation result of the first sampling point is greater than the target threshold, it indicates that a position with a relatively large correlation is detected. Since the correlation peak has an ascending process, by comparing the autocorrelation results corresponding to several sampling points after the first sampling point in the received signal, finding the maximum value, and determining the position of the target sampling point corresponding to the maximum value as the position of the autocorrelation peak, the accuracy of autocorrelation peak determination is improved.

[0051] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned by practice of the present application. Description of the Drawings

[0052] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0053] Figure 1 is the autocorrelation simulation result diagram of the OFDM system provided by the embodiment of the present application in the presence of noise; Figure 2 is the autocorrelation simulation result diagram of the OFDMA system provided by the embodiment of the present application in the presence of noise; Figure 3 is the schematic flowchart of the power line carrier signal synchronization method based on the OFDMA system provided by the embodiment of the present application; Figure 4 is the schematic diagram of the first window and the second window provided by the embodiment of the present application; Figure 5 is the schematic structural diagram of the power line carrier signal synchronization device based on the OFDMA system provided by the embodiment of the present application; Figure 6 is the schematic structural diagram of the electronic device provided by the embodiment of the present application. Detailed Embodiments

[0054] The technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application fall within the scope of protection of the present application.

[0055] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are usually of the same category, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally represents an "or" relationship between the associated objects before and after.

[0056] Power Line Communication (PLC) is a communication technology that uses existing power lines as a data transmission medium. Among them, High-Speed Power Line Communication (HPLC) is a high-speed communication technology based on PLC, using alternating current power lines as the physical medium for signal transmission. HPLC has a wider bandwidth, higher data rate, can reach the Mbps level, and has lower noise and less interference at higher frequencies, thus providing better performance and reliability. Broadband Power Line Communication (BPLC) is also an important form of PLC, with its bandwidth limited between 2 and 30 MHz, and the communication rate is usually above 1 Mbps.

[0057] OFDM is an efficient digital modulation technique widely used in PLC. OFDM divides the available frequency band into multiple orthogonal subcarriers, converts the input signal into multiple parallel signals, and modulates them onto these subcarriers respectively. Since the subcarriers are orthogonal to each other, the receiving end can recover the information of each subcarrier without distortion. OFDM technology can effectively cope with complex and changing channel environments, improving the reliability and transmission rate of communication. A significant feature of OFDM is that within a time slot, all subcarriers are allocated to one user, and the user occupies the entire system bandwidth during signal transmission, and different users can only occupy different time slots.

[0058] To better support multi-user communication, the OFDMA technology came into being. OFDMA is a multi-user extended version of OFDM technology, which can effectively solve the limitations of OFDM in multi-user scenarios. Different from OFDM, OFDMA allows different subcarriers to be allocated to multiple users within a time slot, and each user only occupies one or more of them, thus realizing shared communication among multiple users in the same time slot. Through OFDMA technology, the power line carrier communication system can better support multi-user access and meet the diverse communication needs in the smart grid.

[0059] However, in an actual communication environment, signals reach the receiving end through multiple different paths during transmission. The lengths of these paths are different, and the attenuation degree and propagation delay of the signals on different paths will also vary, resulting in multipath effects. As a result, the signal received at the receiving end is a superposition of multiple attenuated and time-delayed signals, which will not only affect the position and shape of the synchronization peak, but also disperse the energy of the synchronization peak, causing the position of the maximum peak of the received signal to deviate from the true synchronization peak position. Therefore, the position of the maximum peak may not be the true synchronization peak. If the synchronization peak cannot be accurately determined, it will lead to misjudgment of the signal and demodulation errors, thus affecting the performance and reliability of the communication system.

[0060] Figure 1 is the autocorrelation simulation result diagram of the OFDM system with noise. As Figure 1 shown, in the OFDM system, the peak position is relatively obvious. Generally, the position of the maximum peak is the synchronization peak position, and the peak value of the synchronization peak is significantly larger than the autocorrelation results of the sampling points at other positions, and the peak position is relatively sharp. Figure 2 is the autocorrelation simulation result diagram of the OFDMA system with noise. As Figure 2 shown, in the OFDMA system, the superposition of noise and multipath effects makes the autocorrelation peak not obvious, and the autocorrelation results of the sampling points fluctuate greatly. At this time, the difference between the position of the maximum peak and the autocorrelation results of other sampling points is not obvious either. In this application, the first window is determined through the position of the maximum peak, and then combined with the signal-to-noise ratio of the first window, so as to accurately judge whether the position of the maximum peak is a valid peak; at the same time, the influence of noise is removed during the signal-to-noise ratio judgment process, thus improving the accuracy of the valid peak judgment; in the case where the maximum peak is a valid peak, finally, the synchronization peak position is determined according to the autocorrelation peak position within the first window, thus considering the time-delay influence caused by multipath effects and obtaining an accurate synchronization peak position.

[0061] Next, in conjunction with the accompanying drawings, the power line carrier signal synchronization and device based on the OFDMA system provided by the embodiments of the present application will be described in detail through specific embodiments and their application scenarios.

[0062] Among them, the power line carrier signal synchronization method based on the OFDMA system can be applied to a terminal, and can be specifically executed by hardware or software in the terminal.

[0063] The terminal includes, but is not limited to, portable communication devices such as mobile phones or tablets with a touch-sensitive surface (such as a touch screen display and / or a touchpad). It should also be understood that in some embodiments, the terminal may not be a portable communication device, but a desktop computer with a touch-sensitive surface (such as a touch screen display and / or a touchpad).

[0064] In each of the following embodiments, a terminal including a display and a touch-sensitive surface is described. However, it should be understood that the terminal may include one or more other physical user interface devices such as a physical keyboard, a mouse, and a joystick.

[0065] The power line carrier signal synchronization method based on the OFDMA system provided in the embodiments of this application. The execution subject of this method can be an electronic device or a functional module or functional entity in the electronic device that can implement this method. The electronic devices mentioned in the embodiments of this application include, but are not limited to, mobile phones, tablet computers, computers, cameras, and wearable devices, etc. Hereinafter, taking the electronic device as the execution subject, the power line carrier signal synchronization method provided in the embodiments of this application will be described.

[0066] Figure 3 is a schematic flowchart of the power line carrier signal synchronization method based on the OFDMA system provided in the embodiments of this application. As Figure 3 shown, the power line carrier signal synchronization method based on the OFDMA system includes: step 310, step 320, step 330, and step 340.

[0067] Step 310: Perform cross-correlation processing on the received signal and the reference sequence to obtain a target cross-correlation result, and perform autocorrelation operation on the target cross-correlation result and the target historical cross-correlation result to obtain a target autocorrelation result.

[0068] Signal synchronization refers to the process in a communication system where the receiving end and the transmitting end are consistent in time, frequency, and phase. In a communication system, the transmitting end sends signals according to a certain timing structure, and the receiving end needs to accurately identify the starting point, symbol boundary, and frequency and phase information of the received signal in order to correctly demodulate and decode the signal.

[0069] During the communication process, signals are usually transmitted in the form of data frames. A data frame is the basic transmission unit of a signal and contains parts such as synchronization information, control information, and user data. In order to correctly receive and process these data frames, the receiving end needs to be consistent with the transmitting end in time, frequency, and phase, which requires signal synchronization. The starting position of the data frame is a reference point in the synchronization process. By determining the position of the synchronization peak, the receiving end can accurately find the starting position of the data frame. Further, the receiving end can determine the data symbols based on the starting position, thereby correctly demodulating and parsing the information in the data frame and achieving reliable data transmission.

[0070] In the embodiments of the present application, the reference sequence is a pre-known signal sequence with specific characteristics. In power line carrier communication, the reference sequence is usually pre-agreed upon by both the transmitting end and the receiving end. The design of the reference sequence needs to meet some specific requirements, such as having good autocorrelation and cross-correlation characteristics. The length of the reference sequence can be the interval length between the starting positions of different data frames in the received signal, for example, it can be a length covering 1024 sampling points.

[0071] Cross-correlation is used to measure the degree of correlation between the received signal sequence and the known signal sequence, and it can usually be determined by calculating the sum of products of one signal and another signal at different time delays. Autocorrelation is the degree of correlation between a signal and its own values at different time delays. If the time series has strong autocorrelation at a certain time delay, it indicates that there is a certain degree of repetition or periodicity in the sequence at this delay time.

[0072] Therefore, the cross-correlation operation can be first performed on the received signal and the known reference sequence to obtain the cross-correlation result. Whenever a cross-correlation result is calculated, it can be stored, and then the autocorrelation operation can be performed on the cross-correlation result and the previously calculated cross-correlation results to obtain the autocorrelation result.

[0073] In some embodiments, performing cross-correlation processing on the received signal and the reference sequence to obtain the target cross-correlation result includes: Performing cross-correlation calculation on the signal sequence within the current sliding window in the received signal and the reference sequence to obtain the target cross-correlation result; the target cross-correlation result is the cross-correlation result of the first sampling point; the first sampling point is within the signal sequence in the current sliding window.

[0074] In this embodiment, the sampling point is a discrete representation of the received signal in terms of time and amplitude, and the sampling point carries the key information of the received signal. By sampling the received signal, a series of sampling points can be used to approximately represent the original continuous received signal.

[0075] The sliding window is an analysis window that can move on the received signal and is used to analyze the characteristics of the signal segment by segment. The length of the sliding window is the same as the length of the reference sequence. The sliding window can slide on the received signal with a preset step size. For example, each sliding step size is 1 sampling point, 2 sampling points, or other numbers of sampling points. The current sliding window is the current position where the sliding window slides to.

[0076] In this embodiment, the signal sequence within the current sliding window can be cross-correlated with the reference sequence to obtain the cross-correlation result of the first sampling point. Among them, the first sampling point can be a specific sampling point within the current sliding window, and the relative position of this specific sampling point within the sliding window is fixed. For example, the specific sampling point can be the first sampling point, the second sampling point, or the sampling point at other positions within the sliding window.

[0077] In some embodiments, cross-correlating the signal sequence within the current sliding window in the received signal with the reference sequence to obtain the target cross-correlation result includes: Calculating the symbol coefficient corresponding to each sampling point according to the signal amplitude corresponding to each sampling point in the signal sequence within the current sliding window; among them, the positive and negative of the signal amplitude are consistent with the positive and negative of the symbol coefficient; Multiplying the symbol coefficients corresponding to the sampling points at the same positions in the signal sequence and the reference sequence within the current sliding window, and summing the multiplication results of each sampling point to obtain the target cross-correlation result.

[0078] In the related art, the calculation of the cross-correlation result usually requires multiplying and adding the signal amplitudes of different sampling points in two signals, and the calculation is relatively complex.

[0079] In this embodiment, the calculation of the cross-correlation result can take the symbol coefficient of the signal amplitude, and calculate the cross-correlation result by multiplying and adding the symbol coefficients, thereby simplifying the calculation process, improving the calculation efficiency, and at the same time retaining the basic characteristics of the signal.

[0080] Specifically, in the signal sequence and the reference sequence within the current sliding window, both contain multiple sampling points, and each sampling point has a corresponding signal amplitude. The signal amplitude is the instantaneous value of the sampling point, which can be positive, negative, or zero, and the signal amplitude reflects the intensity and direction of the signal at different time points.

[0081] For each sampling point, a symbol coefficient can be determined according to the positive and negative of the signal amplitude. The symbol coefficient is a simple mark used to represent the direction of the signal amplitude. If the signal amplitude is positive, the symbol coefficient is +1; if the signal amplitude is negative, the symbol coefficient is -1; if the signal amplitude is zero, the symbol coefficient is 0.

[0082] For example, the signal sequence within the current sliding window is , where is the signal amplitude of the th sampling point, and the corresponding symbol coefficient is , where is the symbol coefficient of the th sampling point: , After determining the symbol coefficients of the signal sequence and the reference sequence within the current sliding window, the symbol coefficients corresponding to the sampling points at the same positions in the signal sequence and the reference sequence within the current sliding window can be multiplied, and the multiplication results of each sampling point are summed to obtain the cross-correlation result of the first sampling point.

[0083] For example, the symbol coefficient corresponding to the current sliding window is , and the symbol coefficient corresponding to the reference sequence is , being the symbol coefficient of the -th sampling point in the reference sequence, then the cross-correlation result of the first sampling point can be expressed as: , In this embodiment, by determining the symbol coefficient of each sampling point according to the signal amplitude corresponding to each sampling point in the signal sequence within the current sliding window, the positive and negative of the signal amplitude are consistent with the positive and negative of the symbol coefficient, so that complex multiplication operations are not required in the cross-correlation calculation, simplifying the calculation process and reducing the calculation complexity.

[0084] In some embodiments, performing an autocorrelation operation on the target cross-correlation result and the target historical cross-correlation result to obtain the target autocorrelation result includes: Performing an autocorrelation calculation on the target cross-correlation result and the target historical cross-correlation result to obtain the target autocorrelation result; the target autocorrelation result is the autocorrelation result of the first sampling point; the target historical cross-correlation result is the cross-correlation result of the second sampling point, and the second sampling point is located in the signal sequence within the historical sliding window.

[0085] In this embodiment, the target historical cross-correlation result is the cross-correlation result of the second sampling point. The second sampling point is a specific sampling point within the historical sliding window, and the position of the second sampling point within the historical sliding window is the same as the position of the first sampling point within the previous sliding window, for example, both are the first sampling point within the sliding window.

[0086] In some embodiments, the distance between the first sampling point and the second sampling point can be the length of the sliding window, for example, a distance of 1024 sampling points. By performing an autocorrelation calculation on the cross-correlation result of the first sampling point and the cross-correlation result of the second sampling point, the autocorrelation result of the first sampling point can be obtained.

[0087] In some embodiments, performing an autocorrelation calculation on the target cross-correlation result and the target historical cross-correlation result to obtain the target autocorrelation result includes: Multiplying the cross-correlation result of the first sampling point and the cross-correlation result of the second sampling point to obtain the target autocorrelation result.

[0088] Since the cross-correlation peak may vary in different noise environments and is sometimes not obvious, this embodiment performs autocorrelation based on the cross-correlation result, that is, by accumulating two cross-correlation results at a preset interval, that is, multiplying the cross-correlation result of the first sampling point by the cross-correlation result of the second sampling point, so that a more obvious correlation peak can be obtained.

[0089] In this embodiment, the autocorrelation result of the first sampling point is directly obtained by multiplying the cross-correlation result of the first sampling point with the cross-correlation result of the second sampling point, which can effectively capture the intrinsic correlation of the signal and simplify the process of solving the autocorrelation result.

[0090] In related technologies, the synchronization peak position is usually determined by calculating the cross-correlation result between the signal and the local sequence. This method can achieve effective synchronization under ideal channel conditions, but the strong noise interference (such as narrowband interference, background noise) and low signal-to-noise ratio environment of the power line channel will seriously weaken the significance of the correlation peak. For example, burst pulse noise in the power line may cause false correlation peaks and cause misjudgment; the cross-correlation peak is not obvious under low signal-to-noise ratio, which is also easy to misjudgment.

[0091] In this embodiment, the signal sequence in the received signal located in the current sliding window is compared with the reference sequence through cross-correlation calculation, so that the similarity between the signal sequence and the reference sequence can be identified, and the cross-correlation result of the first sampling point obtained is subjected to autocorrelation calculation with the cross-correlation result of the second sampling point in the historical sliding window to obtain the autocorrelation result of the first sampling point. The combination of cross-correlation and autocorrelation can more comprehensively capture the characteristics of the signal and improve the accuracy of autocorrelation peak detection.

[0092] Step 320: Analyze the position of a first target autocorrelation peak in the received signal based on the target autocorrelation result; the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the received signal.

[0093] When there is a large correlation between the received signal and the reference, the autocorrelation results obtained in history will show a peak shape in the data distribution, that is, the autocorrelation peak.

[0094] The peak value of the autocorrelation peak can be represented by the autocorrelation result of the sampling point. When the autocorrelation result of the sampling point is greater than a preset threshold, the location of the sampling point can be considered as the location of the autocorrelation peak. Further, by comparing the autocorrelation results of multiple sampling points, the autocorrelation peak with the largest peak value can be found, that is, the first target autocorrelation peak.

[0095] In some embodiments, analyzing the position of a first target autocorrelation peak in the received signal based on the target autocorrelation result includes: When the absolute value of the target autocorrelation result is greater than the target threshold, update the target threshold with the absolute value of the target autocorrelation result; Search for the autocorrelation results of the sampling points after the first sampling point. When the absolute value of the autocorrelation result of the sampling points after the first sampling point is greater than the updated target threshold, update the target threshold with the absolute value of the autocorrelation result of the sampling points after the first sampling point until the absolute values of the autocorrelation results of the target number of sampling points are less than or equal to the updated target threshold; Determine the position of the first target autocorrelation peak according to the position of the target sampling point corresponding to the updated target threshold.

[0096] In this embodiment, the target threshold is a preset threshold, which can be used to judge whether the autocorrelation result is large enough, so as to determine whether there is a significant autocorrelation peak. The target threshold can be adjusted according to the characteristics of the received signal and the noise level.

[0097] If the absolute value of the autocorrelation result is greater than the target threshold, it indicates that there may be a significant autocorrelation peak near the first sampling point. The position of the autocorrelation peak can be determined according to the position of the first sampling point. For example, the position of the first sampling point can be determined as the position of the autocorrelation peak.

[0098] Since the autocorrelation peak has a rising process, the position of the first sampling point may be at the foot or waist of the peak. Therefore, the position of the peak can be searched by dynamically adjusting the target threshold. Specifically, when the absolute value of the target autocorrelation result is greater than the target threshold, update the target threshold with the absolute value of the target autocorrelation result. Search for the autocorrelation results of the sampling points after the first sampling point. If the absolute value of the autocorrelation result of the searched sampling point is greater than the updated target threshold, use the absolute value of the autocorrelation result of this sampling point as the new target threshold and continue to search backward until the target threshold is stable. For example, continue to search backward for the target number of sampling points, and the autocorrelation results of these sampling points are all less than or equal to the target threshold. Among them, the target number can be 15, 20, 30, 50, 60 or other numbers. The target number can be set according to the characteristics of the signal and the expected width of the autocorrelation peak. For example, if the expected autocorrelation peak is wider, the target number can be set larger; if the expected autocorrelation peak is narrower, the target number can be set smaller.

[0099] In one example, the comparison can start from the first sampling point after the first sampling point. If the absolute value of the autocorrelation result of the first sampling point is greater than the absolute value of the autocorrelation result of the first sampling point, the absolute value of the autocorrelation result of the first sampling point can be updated to the target threshold value. Then, the autocorrelation result of the second sampling point after the first sampling point is compared with the updated target threshold value. If the absolute value of the autocorrelation result of the second sampling point is less than the target threshold value, the target threshold value is not updated. If the absolute value of the autocorrelation result of the second sampling point is greater than the target threshold value, the absolute value of the autocorrelation result of the second sampling point is updated to the target threshold value, and so on. After updating the absolute value of the autocorrelation result of the a-th sampling point to the target threshold value, continue to search backward for the target number of sampling points. If the autocorrelation results of these sampling points are all less than or equal to the target threshold value, the a-th sampling point can be determined as the target sampling point, and the position where the a-th sampling point is located can be determined as the position of the autocorrelation peak.

[0100] In this embodiment, when the absolute value of the autocorrelation result of the first sampling point is greater than the target threshold, it indicates that a position with a relatively large correlation is detected. Since there is an ascending process for the correlation peak, by comparing the autocorrelation results corresponding to several sampling points after the first sampling point in the received signal, the maximum value is found, and the position of the target sampling point corresponding to the maximum value is determined as the position of the autocorrelation peak, which improves the accuracy of determining the autocorrelation peak.

[0101] Step 330: Determine a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak.

[0102] In the embodiments of the present application, a specific interval, that is, a first window, can be determined according to the position of the first target autocorrelation peak. The size and position of the first window can be determined according to the position of the first target autocorrelation peak and the characteristics of the signal. For example, the first window can be centered on the first target autocorrelation peak and extend a certain range to both sides, or the first target autocorrelation peak can be located at any position within the first window.

[0103] In some embodiments, determining a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak includes: Determine the first target length of the first window; Determine the range with the position of the target autocorrelation peak as the center and the length of the first target length as the first window.

[0104] In this embodiment, the first target length can also be preset or determined based on the characteristics of the received signal. For example, if the periodic characteristics of the received signal are very clear and the synchronization requirement is high, the first target length can be set relatively short to more accurately capture the synchronization characteristics of the received signal. If the noise level of the received signal is high or the periodic characteristics of the signal are not obvious enough, a longer first target length can be set to include more signal characteristics, thereby improving the reliability of synchronization.

[0105] After determining the first target length, a range centered on the position of the target autocorrelation peak and with a length of the first target length can be determined as the first window. For example, the length of the window can be measured by the number of sampling points. If the first target length is 40 sampling points, that is, in addition to the sampling point corresponding to the first target correlation peak, the length of the first window also covers 40 sampling points. The range of the first 20 sampling points and the last 20 sampling points before the first target correlation peak can be used as the first window. Of course, the length of the window can also be measured by time, and the embodiments of the present application do not limit this.

[0106] In this embodiment, by clarifying the first target length of the first window and defining the window range centered on the position of the target autocorrelation peak, it is possible to focus on the key feature area of the signal, reduce misjudgment caused by noise or interference in a complex signal environment, make better use of the autocorrelation characteristics of the signal, accurately locate the synchronization peak position, and improve the accuracy of signal synchronization.

[0107] In some embodiments, determining the first target length of the first window includes: Obtaining the maximum time delay of the received signal propagating along multiple different paths; Determining the first target length according to the maximum time delay and the sampling rate of the received signal.

[0108] During the communication process, the received signal usually propagates along multiple different paths. The lengths of these paths are different, resulting in different arrival times of the signal at the receiving end. The maximum time delay of the received signal propagating along multiple different paths can be obtained, and the first target length can be determined according to the maximum time delay and the sampling rate of the received signal. For example, the maximum time delay is 4 μs and the sampling rate is 20 MHz (i.e., the sampling interval is 50 ns), then the first target length is 4×20 = 80, that is, the first target length is 80 sampling points. The range of the first 40 points and the last 40 points before the first target correlation peak can be used as the first window.

[0109] In this embodiment, the maximum time delay reflects the time difference of signal propagation on different paths, and the sampling rate determines the degree of signal discretization in time. By combining the maximum time delay with the sampling rate, the length of the first window can be determined such that the first window can cover the key feature region of the signal, contain as many relevant peaks of valid multipath components as possible, and make the determination of the synchronization peak position more accurate.

[0110] Step 340: Determine the synchronization peak position in the received signal based on the position of the autocorrelation peak within the first window.

[0111] Considering that in an OFDMA system, multiple users will cause time delay, resulting in multipath effects, and the autocorrelation result during synchronization will have peaks with different energies within a certain range. At the same time, the influence of superimposed noise causes the maximum autocorrelation peak not necessarily to be a valid autocorrelation peak. Therefore, before determining the synchronization peak position in the received signal based on the position of the autocorrelation peak within the first window, it is necessary to determine whether the first target autocorrelation peak is a valid peak.

[0112] In some embodiments, determining the synchronization peak position in the received signal based on the position of the autocorrelation peak within the first window includes: Determine whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the first window; In the case where the first target autocorrelation peak is a valid peak, determine the synchronization peak position in the received signal based on the position of the autocorrelation peak within the first window.

[0113] Since the multipath effect superimposed with the noise energy has a greater impact on the autocorrelation peak value, in order to determine whether the first target autocorrelation peak is a valid peak, that is, a false peak not caused by noise, it is possible to determine whether the first target autocorrelation peak is a valid peak according to the signal-to-noise ratio of the first window.

[0114] In this embodiment, by detecting the signal-to-noise ratio of the first window during the synchronization process, the signal quality can be accurately identified, and thus it can be accurately determined whether the first target autocorrelation peak is a valid peak.

[0115] In some embodiments, determining whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the first window includes: Calculate the signal-to-noise ratio of the first window; In the case where the signal-to-noise ratio is greater than the target signal-to-noise ratio threshold, determine that the first target autocorrelation peak is a valid peak.

[0116] In this embodiment, the signal-to-noise ratio of the first window can be calculated. In the case where the signal-to-noise ratio is greater than the target signal-to-noise ratio threshold, it indicates that the reliability of the signal is relatively high and it is less affected by noise. Determine that the first target autocorrelation peak is a valid peak, and the synchronization peak position in the received signal can be determined based on the position of the autocorrelation peak within the first window.

[0117] Considering that in the absence of multipath effects, whether the maximum peak is valid is determined by whether the signal-to-noise ratio of the maximum peak is greater than the target signal-to-noise ratio threshold, and the target signal-to-noise ratio threshold is set relatively high. In the presence of multipath effects, the signal-to-noise ratio of the maximum peak will decrease. Therefore, a relatively low target signal-to-noise ratio threshold needs to be set, and the signal-to-noise ratio within the first window is used to determine whether the maximum peak is a valid peak, which can reduce the influence of multipath effects and noise and improve the accuracy of signal synchronization.

[0118] In some embodiments, calculating the signal-to-noise ratio of the first window includes: Searching for a second window with a second target length based on the position of the first target autocorrelation peak; the second window does not include the autocorrelation peak; Determining the average autocorrelation result of the sampling points of the received signal within the second window as the average noise energy within the second window; Taking the average noise energy within the second window as the average noise energy within the first window, and combining the autocorrelation result of the sampling points of the received signal within the first window, calculating the average signal energy of the first window without including noise; Determining the ratio of the average signal energy to the average noise energy as the signal-to-noise ratio.

[0119] In this embodiment, noise is the random interference part in the signal, which will mask the true characteristics of the signal. The average noise energy refers to the average value of the energy of the noise component in the signal.

[0120] To accurately estimate the average noise energy, a second window can be searched according to the position of the first target autocorrelation peak. The second window can be a position in the received signal before or after the first target autocorrelation peak, and the second window does not include the autocorrelation peak.

[0121] The second target length of the second window can be the same as or different from the first target length. The second target length can be greater than the first target length. It should be noted that the interval between the positions of different synchronization peaks in the received signal is theoretically fixed. For example, the interval is fixed at a distance of 1024 sampling points. Therefore, the second target length can be less than the distance of 1024 sampling points. For example, the second target length can be set to 600 sampling points, 800 sampling points, 900 sampling points or other values. In one example, Figure 4 is a schematic diagram of the first window and the second window, as Figure 4 shown, in the second window, the autocorrelation peak is not included.

[0122] Since there is no autocorrelation peak in the second window, it can be considered that the signal components in the second window are mainly composed of noise. The autocorrelation results of all sampling points in the second window can be averaged to obtain the average noise energy. That is, the average noise energy is the average value of the autocorrelation results of the sampling points in the second window.

[0123] In this embodiment, since the position of the second window is adjacent to the position of the first target autocorrelation peak, it can be considered that the noise characteristics in the second window are similar to those in the first window. Therefore, the average noise energy in the second window can be used to represent the noise level in the first window.

[0124] In this embodiment, the average signal energy in the first window can be calculated based on the average noise energy. Specifically, the autocorrelation result of each sampling point in the first window can be subtracted by the average energy of the noise to obtain the signal energy in the first window, and then the signal energies in the first window are accumulated and averaged to obtain the average signal energy. That is, subtract the average noise energy from the autocorrelation result of each sampling point in the first window to obtain the signal energy in the first window; then accumulate and average the signal energies in the first window to obtain the average signal energy.

[0125] In some embodiments, the formula can be used: , to calculate the average signal energy; where, represents the average signal energy of the signal without noise in the first window, represents the sampling points in the first window autocorrelation result, represents the number of sampling points in the first window, represents the average noise energy in the second window.

[0126] In this embodiment, considering that the influence of noise energy superposition on the multipath effect on the autocorrelation peak is relatively large, by searching for the second window without autocorrelation peak according to the position of the first target autocorrelation peak, since there is no autocorrelation peak in the second window, it can be considered that the received signal in the second window is mainly composed of noise. Using the average noise energy in the second window as the average noise energy in the first window can reduce the influence of noise energy and make the calculation of the signal-to-noise ratio more accurate. From Figure 4It can be seen that the energy in the first window is affected by multipath effects and noise energy, resulting in little difference between the autocorrelation results in the first window and the autocorrelation results in the second window. In the embodiment of the present application, the energy in the first window is subtracted from the energy in the second window, so as to reduce the influence of noise on the signal-to-noise ratio in the first window, and thus the calculated signal-to-noise ratio is more accurate. Further, it can accurately determine whether the autocorrelation peak in the first window is a valid peak, reduce misjudgment, and improve the accuracy of judgment.

[0127] In the embodiment of the present application, the position information of the autocorrelation peak in the first window can be used to determine the position of the synchronization peak in the received signal. In one example, as Figure 4 shown, in the first window, in addition to the first target autocorrelation peak, there are other autocorrelation peaks, where the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the first window.

[0128] In some embodiments, the average value of the positions of multiple autocorrelation peaks in the first window can be determined as the position of the synchronization peak in the received signal. The position of the synchronization peak in the received signal can also be determined by other means. For example, weights can be assigned according to the peak values of different autocorrelation peaks, and the higher the peak value, the higher the weight is assigned. Then, the positions of multiple autocorrelation peaks are weighted and averaged, and the weighted average value is determined as the position of the synchronization peak in the received signal. Of course, the position of the synchronization peak in the received signal can also be determined by other means based on the positions of the autocorrelation peaks in the first window, and the embodiments of the present application do not limit this.

[0129] In some embodiments, determining the position of the synchronization peak in the received signal based on the positions of the autocorrelation peaks in the first window includes: Obtaining multiple second target autocorrelation peaks in the first window; the multiple second target autocorrelation peaks at least include the first target autocorrelation peak; Determining the position of the synchronization peak in the received signal according to the positions of the multiple second target autocorrelation peaks.

[0130] In this embodiment, the first window contains multiple autocorrelation peaks. For example, the peak values of these autocorrelation peaks are greater than the initial peak threshold, and multiple second target autocorrelation peaks can be screened from the multiple autocorrelation peaks in the first window; the multiple second target autocorrelation peaks at least include the first target autocorrelation peak.

[0131] In this embodiment, by comprehensively considering the position information of multiple autocorrelation peaks, the characteristics of the signal can be captured more comprehensively, the synchronization error caused by the deviation of the position of the maximum peak from the true synchronization point is reduced, and the accuracy of signal synchronization is improved.

[0132] In some embodiments, the second target autocorrelation peak is an autocorrelation peak whose peak value in the first window meets the target requirements.

[0133] In this embodiment, by using the autocorrelation peak whose peak value meets the target requirements as a reference to determine the position of the synchronization peak in the received signal, the positions of multiple key peaks related to the synchronization peak position are integrated, which can reduce the overall deviation of the synchronization position and improve the accuracy of signal synchronization.

[0134] In this embodiment, the higher the peak value of the autocorrelation peak, the more significant the periodic or repetitive characteristics of the position corresponding to the autocorrelation peak in the received signal, and the more likely it is the synchronization peak position. Therefore, the target requirements can be the n autocorrelation peaks with the largest peak values among the autocorrelation peaks within the first window. For example, n can be 2, 3, 4, 5 or other numbers. The target requirements can also be the autocorrelation peaks whose peak values are greater than the target threshold within the first window. By selecting the n autocorrelation peaks with the largest peak values, the autocorrelation characteristics of the signal can be fully utilized, or by setting the target threshold, some false peaks caused by noise can be excluded, and multiple key peaks related to the starting position of the data frame can be screened out from the autocorrelation peaks within the first window, improving the accuracy of signal synchronization.

[0135] In some embodiments, determining the position of the synchronization peak in the received signal according to the positions of multiple second target autocorrelation peaks includes: Calculating the average value or weighted average value of the positions of multiple second target autocorrelation peaks; Determining the average value or weighted average value as the position of the synchronization peak in the received signal.

[0136] In this embodiment, the position information of multiple second target autocorrelation peaks can be utilized to calculate the average value of these positions and determine the average value as the position of the synchronization peak in the received signal.

[0137] Alternatively, different weights can be assigned according to the peak values or other characteristics of each second target correlation peak, and then the weighted average value of the positions is calculated, and the weighted average value is determined as the position of the synchronization peak in the received signal.

[0138] In this embodiment, by comprehensively considering the position information of multiple autocorrelation peaks and adopting the method of average value or weighted average value, the synchronization deviation caused by the error or noise influence of a single autocorrelation peak can be reduced. Introducing the weighted average value can assign different weights according to the intensity or other characteristics of the autocorrelation peak, so as to more accurately locate the synchronization peak position.

[0139] According to an embodiment of the present application, determining the average value or weighted average value of the positions of multiple second target autocorrelation peaks includes: Determining the sampling points corresponding to multiple second target autocorrelation peaks; Taking the positions of the sampling points corresponding to multiple second target autocorrelation peaks as the positions of multiple second target autocorrelation peaks, and determining the average value or weighted average value.

[0140] In this embodiment, the position of the autocorrelation peak can be represented by sampling points. For example, if the autocorrelation result of the 10th sampling point is greater than a certain value, the peak corresponding to the 10 sampling points is the autocorrelation peak, the autocorrelation result is the peak value of this autocorrelation peak, and the position of the autocorrelation peak is the position where the 10th sampling point is located.

[0141] In this embodiment, the positions of the sampling points corresponding to multiple second target autocorrelation peaks can be used as the positions of the multiple second target autocorrelation peaks to determine the average value or the weighted average value. For example, if there are three second target autocorrelation peaks in the first window, and the positions of the corresponding sampling points are X1, X2, and X3 respectively, and the average value (X1 + X2 + X3) / 3 is determined, then the position of the synchronization peak in the received signal is (X1 + X2 + X3) / 3.

[0142] In this embodiment, by identifying the position of the autocorrelation peak through the sampling point position and calculating the average value or the weighted average value based on the positions of these sampling points, the position of the synchronization peak can be accurately located.

[0143] The power line carrier signal synchronization method based on the OFDMA system provided by the embodiments of the present application analyzes and processes the received signal and the reference sequence, combines the cross-correlation and autocorrelation methods, can capture the signal characteristics more comprehensively, improves the accuracy of autocorrelation peak detection. Since the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the received signal, the first window is determined through the position of the first target autocorrelation peak, narrowing the analysis range of signal synchronization, and comprehensively determining the starting position of the data frame in the received signal based on the positions of the autocorrelation peaks in the first window, thereby reducing the synchronization error caused by the deviation of the maximum peak position from the true synchronization point and improving the accuracy of signal synchronization.

[0144] The power line carrier signal synchronization method based on the OFDMA system provided by the embodiments of the present application may be executed by a power line carrier signal synchronization device based on the OFDMA system. In the embodiments of the present application, taking the power line carrier signal synchronization device based on the OFDMA system executing the power line carrier signal synchronization method based on the OFDMA system as an example, the power line carrier signal synchronization device based on the OFDMA system provided by the embodiments of the present application is described.

[0145] The embodiments of the present application also provide a power line carrier signal synchronization device based on the OFDMA system.

[0146] Figure 5 It is a schematic structural diagram of the power line carrier signal synchronization device based on the OFDMA system provided by the embodiments of the present application, as Figure 5 shown, the power line carrier signal synchronization device based on the OFDMA system includes: A processing module 510 is configured to perform cross-correlation processing on the received signal and a reference sequence to obtain a target cross-correlation result, and perform autocorrelation operation on the target cross-correlation result and a target historical cross-correlation result to obtain a target autocorrelation result; An analysis module 520 is configured to analyze the position of a first target autocorrelation peak in the received signal based on the target autocorrelation result; the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the received signal; A first determination module 530 is configured to determine a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak; A second determination module 540 is configured to determine the position of a synchronization peak in the received signal based on the positions of the autocorrelation peaks within the first window.

[0147] The power line carrier signal synchronization device based on the OFDMA system provided by the embodiments of the present application analyzes and processes the received signal and a reference sequence, combines cross-correlation and autocorrelation methods, can capture the characteristics of the signal more comprehensively, improves the accuracy of autocorrelation peak detection. Since the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the received signal, the first window is determined according to the position of the first target autocorrelation peak, narrowing the analysis range of signal synchronization, and comprehensively determining the starting position of the data frame in the received signal based on the positions of the autocorrelation peaks within the first window, thereby reducing the synchronization error caused by the deviation of the maximum peak position from the true synchronization point and improving the accuracy of signal synchronization.

[0148] In some embodiments, the second determination module 540 is further configured to: Judge whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the received signal within the first window; When the first target autocorrelation peak is a valid peak, determine the position of the synchronization peak in the received signal based on the positions of the autocorrelation peaks within the first window.

[0149] In some embodiments, the second determination module 540 is further configured to: Calculate the signal-to-noise ratio of the received signal within the first window; When the signal-to-noise ratio is greater than the target signal-to-noise ratio threshold, determine that the first target autocorrelation peak is a valid peak.

[0150] In some embodiments, the second determination module 540 is further configured to: Search for a second window with a second target length from the received signal based on the position of the first target autocorrelation peak; no autocorrelation peak is included within the second window; Determine the average value of the autocorrelation results of the sampling points of the received signal within the second window as the average noise energy within the second window; Take the average noise energy in the second window as the average noise energy in the first window, and combine the autocorrelation results of the sampling points of the received signal in the first window to calculate the average signal energy of the received signal in the first window excluding noise; Determine the ratio of the average signal energy to the average noise energy as the signal-to-noise ratio.

[0151] In some embodiments, the second determination module 540 is further configured to: According to the formula: , Calculate the average signal energy; Wherein, represents the average signal energy of the signal excluding the noise signal in the first window, represents the sampling points in the first window autocorrelation result of, represents the number of sampling points in the first window, represents the average noise energy in the second window.

[0152] In some embodiments, the first determination module 530 is further configured to: Determine the first target length of the first window; Determine the range centered on the position of the target autocorrelation peak and with a length of the first target length as the first window.

[0153] In some embodiments, the second determination module 540 is further configured to: Obtain multiple second target autocorrelation peaks in the first window; the multiple second target autocorrelation peaks include at least the first target autocorrelation peak; Determine the position of the synchronization peak in the received signal according to the positions of the multiple second target autocorrelation peaks.

[0154] In some embodiments, the second determination module 540 is further configured to: Calculate the average value or weighted average value of the positions of the multiple second target autocorrelation peaks; Determine the average value or weighted average value as the position of the synchronization peak in the received signal.

[0155] In some embodiments, the second determination module 540 is further configured to: Determine the sampling points corresponding to the multiple second target autocorrelation peaks; Use the positions of the sampling points corresponding to the multiple second target autocorrelation peaks as the positions of the multiple second target autocorrelation peaks to determine the average value or weighted average value.

[0156] In some embodiments, the processing module 510 is further configured to: Perform a cross-correlation calculation on the signal sequence within the current sliding window in the received signal and the reference sequence to obtain a target cross-correlation result; the target cross-correlation result is the cross-correlation result of the first sampling point; the first sampling point is located in the signal sequence within the current sliding window. Perform an autocorrelation calculation on the target cross-correlation result and the target historical cross-correlation result to obtain a target autocorrelation result; the target autocorrelation result is the autocorrelation result of the first sampling point; the target historical cross-correlation result is the cross-correlation result of the second sampling point, and the second sampling point is located in the signal sequence within the historical sliding window.

[0157] In some embodiments, the processing module 510 is further configured to: Calculate the symbol coefficient corresponding to each sampling point according to the signal amplitude corresponding to each sampling point in the signal sequence within the current sliding window; wherein, the positive or negative of the signal amplitude is consistent with the positive or negative of the symbol coefficient. Multiply the symbol coefficients corresponding to the sampling points at the same positions in the signal sequence within the current sliding window and the reference sequence, and sum the multiplication results of each sampling point to obtain the target cross-correlation result.

[0158] In some embodiments, the processing module 510 is further configured to: Multiply the cross-correlation result of the first sampling point by the cross-correlation result of the second sampling point to obtain the target autocorrelation result.

[0159] In some embodiments, the analysis module 520 is further configured to: In the case where the absolute value of the target autocorrelation result is greater than the target threshold, update the target threshold using the absolute value of the target autocorrelation result. Search for the autocorrelation results of the sampling points after the first sampling point. In the case where the absolute value of the autocorrelation result of the sampling points after the first sampling point is greater than the updated target threshold, update the target threshold using the absolute value of the autocorrelation result of the sampling points after the first sampling point until the absolute values of the autocorrelation results of the target number of sampling points are less than or equal to the updated target threshold. Determine the position of the first target autocorrelation peak according to the position of the target sampling point corresponding to the updated target threshold.

[0160] The power line carrier signal synchronization device based on the OFDMA system in the embodiments of the present application can be an electronic device or a component in an electronic device, such as an integrated circuit or a chip. The electronic device can be a terminal or other devices other than terminals. Exemplarily, the electronic device can be a mobile phone, a tablet computer, a laptop computer, a palm computer, a vehicle-mounted electronic device, a Mobile Internet Device (MID), an augmented reality (AR) / virtual reality (VR) device, a robot, a wearable device, an ultra-mobile personal computer (UMPC), a netbook, or a personal digital assistant (PDA), etc., and can also be a server, a Network Attached Storage (NAS), a personal computer (PC), a television (TV), a teller machine, or a self-service machine, etc. The embodiments of the present application do not make specific limitations.

[0161] The power line carrier signal synchronization device based on the OFDMA system in the embodiments of the present application can be a device with an operating system. The operating system can be the Microsoft (Windows) operating system, the Android operating system, the IOS operating system, or other possible operating systems. The embodiments of the present application do not make specific limitations.

[0162] In some embodiments, Figure 6 is a schematic structural diagram of the electronic device provided by the embodiments of the present application. As Figure 6 shown, the embodiments of the present application also provide an electronic device 600, including a processor 601, a memory 602, and a computer program stored on the memory 602 and executable on the processor 601. When the program is executed by the processor 601, it implements each process of the above-mentioned embodiments of the power line carrier signal synchronization method based on the OFDMA system and can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0163] It should be noted that the electronic devices in the embodiments of the present application include the above-mentioned mobile electronic devices and non-mobile electronic devices.

[0164] The embodiments of the present application also provide a power line carrier signal synchronization system based on the OFDMA system, including: A signal sending device for sending signals; A signal receiving device for executing the above-mentioned power line carrier signal synchronization method based on the OFDMA system.

[0165] The embodiment of the present application also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements each process of the above-mentioned embodiment of the power line carrier signal synchronization method based on the OFDMA system, and can achieve the same technical effect. To avoid repetition, it will not be elaborated here.

[0166] Among them, the processor is the processor in the electronic device in the above-mentioned embodiment. The readable storage medium includes computer-readable storage media, such as computer read-only memory ROM, random access memory RAM, magnetic disks or optical discs, etc.

[0167] The embodiment of the present application also provides a computer program product, including a computer program. When the computer program is executed by a processor, it implements the above-mentioned power line carrier signal synchronization method based on the OFDMA system.

[0168] Among them, the processor is the processor in the electronic device in the above-mentioned embodiment. The readable storage medium includes computer-readable storage media, such as computer read-only memory ROM, random access memory RAM, magnetic disks or optical discs, etc.

[0169] The embodiment of the present application further provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement each process of the above-mentioned embodiment of the power line carrier signal synchronization method based on the OFDMA system, and can achieve the same technical effect. To avoid repetition, it will not be elaborated here.

[0170] It should be understood that the chip mentioned in the embodiment of the present application may also be referred to as a system-on-chip, system chip, chip system or system-on-chip, etc.

[0171] It should be noted that in this article, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising such element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in a reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, the features described with reference to certain examples may be combined in other examples.

[0172] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-described example methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions for causing a terminal (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in various embodiments of the present application.

[0173] The embodiments of the present application have been described above with reference to the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of them fall within the protection scope of the present application.

[0174] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0175] Although embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present application. The scope of the present application is defined by the claims and their equivalents.

Claims

1. A power line carrier signal synchronization method based on an OFDMA system, characterized in that Including: Performing cross-correlation processing on the received signal and a reference sequence to obtain a target cross-correlation result, and performing autocorrelation operation on the target cross-correlation result and a target historical cross-correlation result to obtain a target autocorrelation result; Analyzing the position of the first target autocorrelation peak in the received signal based on the target autocorrelation result; the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the received signal; Determining a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak; Determining the synchronization peak position in the received signal based on the positions of the autocorrelation peaks within the first window.

2. The method according to claim 1, wherein The determining the synchronization peak position in the received signal based on the positions of the autocorrelation peaks within the first window includes: Judging whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the first window; When the first target autocorrelation peak is a valid peak, determining the synchronization peak position in the received signal based on the positions of the autocorrelation peaks within the first window.

3. The method according to claim 2, wherein The judging whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the first window includes: Calculating the signal-to-noise ratio of the first window; When the signal-to-noise ratio is greater than a target signal-to-noise ratio threshold, determining that the first target autocorrelation peak is a valid peak.

4. The method according to claim 3, characterized in that The calculating the signal-to-noise ratio of the received signal within the first window includes: Searching for a second window with a second target length based on the position of the first target autocorrelation peak; no autocorrelation peak is included within the second window; Determining the average autocorrelation result of the sampling points of the received signal within the second window as the average noise energy within the second window; Taking the average noise energy within the second window as the average noise energy within the first window, and combining the autocorrelation results of the sampling points of the received signal within the first window, calculating the average signal energy of the received signal within the first window without noise; Determining the ratio of the signal average energy to the noise average energy as the signal-to-noise ratio.

5. The method according to claim 1, wherein The determining the first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak includes: Determining the first target length of the first window; Determining the range centered on the position of the target autocorrelation peak with a length of the first target length as the first window.

6. The method according to claim 1, characterized in that The determining the synchronization peak position in the received signal based on the positions of the autocorrelation peaks within the first window includes: Obtaining a plurality of second target autocorrelation peaks within the first window; the plurality of second target autocorrelation peaks at least include the first target autocorrelation peak; Determining the synchronization peak position in the received signal according to the positions of the plurality of second target autocorrelation peaks.

7. The method according to claim 6, wherein The determining the synchronization peak position in the received signal according to the positions of the plurality of second target autocorrelation peaks includes: Calculating the average value or weighted average value of the positions of the plurality of second target autocorrelation peaks; Determining the average value or the weighted average value as the synchronization peak position in the received signal.

8. The method according to claim 1, wherein Performing cross-correlation processing on the received signal and the reference sequence to obtain a target cross-correlation result, and performing autocorrelation operation on the target cross-correlation result and the target historical cross-correlation result to obtain a target autocorrelation result, including: Performing cross-correlation calculation on the signal sequence within the current sliding window in the received signal and the reference sequence to obtain a target cross-correlation result; the target cross-correlation result is the cross-correlation result of the first sampling point; the first sampling point is located in the signal sequence within the current sliding window; Performing autocorrelation calculation on the target cross-correlation result and the target historical cross-correlation result to obtain the target autocorrelation result; the target autocorrelation result is the autocorrelation result of the first sampling point; the target historical cross-correlation result is the cross-correlation result of the second sampling point, and the second sampling point is located in the signal sequence within the historical sliding window.

9. The method according to claim 8, characterized in that, Analyzing the position of the first target autocorrelation peak in the received signal based on the target autocorrelation result, including: When the absolute value of the target autocorrelation result is greater than the target threshold, updating the target threshold using the absolute value of the target autocorrelation result; Searching for the autocorrelation results of the sampling points after the first sampling point. When the absolute value of the autocorrelation result of the sampling points after the first sampling point is greater than the updated target threshold, updating the target threshold using the absolute value of the autocorrelation result of the sampling points after the first sampling point until the absolute values of the autocorrelation results of the target number of sampling points are less than or equal to the updated target threshold; Determining the position of the first target autocorrelation peak according to the position of the target sampling point corresponding to the updated target threshold.

10. A power line carrier signal synchronization device based on an OFDMA system, characterized in that Including: A processing module for performing cross-correlation processing on the received signal and the reference sequence to obtain a target cross-correlation result, and performing autocorrelation operation on the target cross-correlation result and the target historical cross-correlation result to obtain a target autocorrelation result; An analysis module for analyzing the position of the first target autocorrelation peak in the received signal based on the target autocorrelation result; the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the received signal; A first determination module for determining a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak; A second determination module for determining the position of the synchronization peak in the received signal based on the position of the autocorrelation peak within the first window.

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