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

Abstract

The present application discloses a power line carrier signal synchronization method and device based on an OFDMA system, which belongs to the field of power line carrier communication technology. The method includes: 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 the 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 the 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 position of the autocorrelation peak in the first window. The present application determines the autocorrelation peak by combining cross-correlation and autocorrelation, and determines the synchronization peak position by combining the position of the autocorrelation peak in the first window, thereby improving the accuracy of signal synchronization.

Description

Technical Field

[0001] The present application belongs to the field of communication technology, and in particular relates to a method and device for synchronizing power line carrier signals based on an OFDMA system. Background Art

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

[0003] However, in real-world communication environments, signals travel through multiple paths to reach the receiver. These paths vary in length, and the signal attenuation and propagation delay along each path also vary. As a result, the signal received by the receiver is a superposition of multiple attenuated and delayed signals. This causes the maximum peak position of the received signal to deviate from the true synchronization peak position, affecting signal synchronization accuracy. Summary of the Invention

[0004] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a method and apparatus for synchronizing power line carrier signals based on an OFDMA system to improve the accuracy of signal synchronization.

[0005] In a first aspect, the present application provides a power line carrier signal synchronization method based on an OFDMA system, comprising:

[0006] 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;

[0007] 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;

[0008] determining a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak;

[0009] The synchronization peak position in the received signal is determined based on the position of the autocorrelation peak in the first window.

[0010] The power line carrier signal synchronization method based on the OFDMA system provided in the embodiment of the present application analyzes and processes the received signal and the reference sequence, combines the cross-correlation and autocorrelation methods, and can more comprehensively capture the characteristics of the signal and improve 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 by the position of the first target autocorrelation peak, which narrows the analysis range of signal synchronization, and the position of the autocorrelation peak in the first window is combined to determine the starting position of the data frame in the received signal, 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.

[0011] According to one embodiment of the present application, determining the synchronization peak position in the received signal based on the position of the autocorrelation peak in the first window includes:

[0012] determining whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the first window;

[0013] In a case where the first target autocorrelation peak is a valid peak, a synchronization peak position in the received signal is determined based on a position of the autocorrelation peak in the first window.

[0014] In this embodiment, considering that in an OFDMA system, multiple users may cause time delays and multipath effects, resulting in the autocorrelation results during synchronization having peaks with different energies within a certain interval, and at the same time, the influence of superimposed noise may cause the maximum autocorrelation peak to not necessarily be a valid autocorrelation peak. By performing signal-to-noise ratio detection on the first window during the synchronization process, the signal quality can be accurately identified, thereby accurately determining whether the first target autocorrelation peak is a valid peak.

[0015] According to one embodiment of the present application, determining whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the received signal in the first window includes:

[0016] Calculating the signal-to-noise ratio of the first window;

[0017] When the signal-to-noise ratio is greater than a target signal-to-noise ratio threshold, the first target autocorrelation peak is determined to be a valid peak.

[0018] In this embodiment, considering that the multipath effect superimposed on the noise energy has a significant impact on the peak value of the autocorrelation peak, a signal-to-noise ratio detection is performed on 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 autocorrelation peak is a valid autocorrelation peak, thereby reducing the influence of noise and improving the accuracy of signal synchronization.

[0019] According to one embodiment of the present application, calculating the signal-to-noise ratio of the first window includes:

[0020] Searching for a second window having a second target length based on the position of the first target autocorrelation peak; the second window does not include the autocorrelation peak;

[0021] Determine an average value of autocorrelation results of sampling points of the received signal in the second window as the average noise energy in the second window;

[0022] Using the average noise energy in the second window as the average noise energy in the first window, and combining the autocorrelation results of the sampling points of the received signal in the first window to calculate the average signal energy excluding noise in the first window;

[0023] The ratio of the signal average energy to the noise average energy is determined as the signal-to-noise ratio.

[0024] According to one embodiment of the present application, according to the formula:

[0025] ,

[0026] Calculating the average energy of the signal;

[0027] in, represents the average energy of the signal in the first window excluding the noise signal, Indicates the sampling point in the first window The autocorrelation results of represents the number of sampling points in the first window, Represents the average noise energy in the second window.

[0028] In this embodiment, considering that the noise energy superimposed on the multipath effect has a significant impact on the autocorrelation peak, a second window that does not include the autocorrelation peak is searched according to the position of the first target autocorrelation peak. Since the second window does not include the autocorrelation peak, it can be considered that the received signal in the second window is mainly composed of noise. The average noise energy in the second window is used as the average noise energy in the first window, which can reduce the influence of the noise energy and make the calculation of the signal-to-noise ratio more accurate.

[0029] According to one embodiment of the present application, determining a first window including the first target autocorrelation peak according to a position of the first target autocorrelation peak includes:

[0030] determining a first target length of the first window;

[0031] A range centered at the position of the target autocorrelation peak and having a length equal to the first target length is determined as the first window.

[0032] 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, the key feature area of the signal can be focused, thereby reducing misjudgment caused by noise or interference in a complex signal environment, and better utilizing the autocorrelation characteristics of the signal to accurately locate the synchronization peak position, thereby improving the accuracy of signal synchronization.

[0033] According to one embodiment of the present application, determining the synchronization peak position in the received signal based on the position of the autocorrelation peak in the first window includes:

[0034] Acquire 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;

[0035] The synchronization peak position in the received signal is determined according to the positions of the plurality of second target autocorrelation peaks.

[0036] 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 maximum peak position deviating from the true synchronization point is reduced, and the accuracy of signal synchronization is improved.

[0037] According to one embodiment of the present application, the second target autocorrelation peak is an autocorrelation peak whose peak value meets the target requirement among the autocorrelation peaks in the first window.

[0038] In this embodiment, the synchronization peak position in the received signal is determined by taking the autocorrelation peak whose peak value meets the target requirements as a reference, and 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.

[0039] According to one embodiment of the present application, the target requirement includes: n autocorrelation peaks with the largest peak values among the autocorrelation peaks in the first window or autocorrelation peaks with a peak value greater than a target threshold among the autocorrelation peaks in the first window.

[0040] In this embodiment, by selecting 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, thereby improving the accuracy of signal synchronization.

[0041] According to one embodiment of the present application, determining the synchronization peak position in the received signal according to the positions of the plurality of second target autocorrelation peaks includes:

[0042] Calculating an average or weighted average of the positions of a plurality of second target autocorrelation peaks;

[0043] The average value or the weighted average value is determined as the synchronization peak position in the received signal.

[0044] In this embodiment, by comprehensively considering the position information of multiple autocorrelation peaks and adopting the average value or weighted average value, the synchronization deviation caused by the error or noise influence of a single autocorrelation peak can be reduced. The introduction of the weighted average value can assign different weights according to the intensity or other characteristics of the autocorrelation peak, thereby more accurately locating the synchronization peak position.

[0045] According to one embodiment of the present application, determining an average value or a weighted average value of the positions of the plurality of second target autocorrelation peaks includes:

[0046] determining a plurality of sampling points corresponding to the second target autocorrelation peaks;

[0047] The sampling point positions corresponding to the plurality of second target autocorrelation peaks are used as the positions of the plurality of second target autocorrelation peaks, and the average value or the weighted average value is determined.

[0048] In this embodiment, the position of the autocorrelation peak is identified by the sampling point positions, and an average value or a weighted average value is calculated based on the positions of these sampling points, so that the synchronization peak position can be accurately located.

[0049] According to one embodiment of the present application, 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 a target historical cross-correlation result to obtain a target autocorrelation result includes:

[0050] performing cross-correlation calculation on a signal sequence in the received signal located within the current sliding window and the reference sequence to obtain a target cross-correlation result; the target cross-correlation result is a cross-correlation result of a first sampling point; the first sampling point is located in the signal sequence within the current sliding window;

[0051] 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.

[0052] In this embodiment, a signal sequence in the received signal within the current sliding window is compared with a reference sequence through cross-correlation calculation, so that similarity between the signal sequence and the reference sequence can be identified. An autocorrelation calculation is performed on the obtained cross-correlation result of the first sampling point 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. By combining the cross-correlation and autocorrelation methods, the characteristics of the signal can be more comprehensively captured, thereby improving the accuracy of autocorrelation peak detection.

[0053] According to one embodiment of the present application, performing cross-correlation calculation on a signal sequence in the received signal located within the current sliding window and the reference sequence to obtain a target cross-correlation result includes:

[0054] Calculating a sign coefficient corresponding to each sampling point based on a signal amplitude corresponding to each sampling point in the signal sequence within the current sliding window; wherein the sign of the signal amplitude is consistent with the sign of the sign coefficient;

[0055] The signal sequence in the current sliding window and the symbol coefficients corresponding to the sampling points at the same position in the reference sequence are multiplied, and the multiplication results of each sampling point are summed to obtain a target cross-correlation result.

[0056] In this embodiment, the sign coefficient of each sampling point is determined based on the signal amplitude corresponding to each sampling point in the signal sequence within the current sliding window. The positive and negative signs of the signal amplitude are kept consistent with the positive and negative signs of the sign coefficient, so that no complex multiplication operations are required in the cross-correlation calculation, which simplifies the calculation process and reduces the calculation complexity.

[0057] According to one embodiment of the present application, performing autocorrelation calculation on the target mutual correlation result and the target historical mutual correlation result to obtain the target autocorrelation result includes:

[0058] The cross-correlation result of the first sampling point is multiplied by the cross-correlation result of the second sampling point to obtain the target autocorrelation result.

[0059] 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.

[0060] According to one embodiment of the present application, analyzing the position of the first target autocorrelation peak in the received signal based on the target autocorrelation result includes:

[0061] When the absolute value of the target autocorrelation result is greater than the target threshold value, updating the target threshold value by using the absolute value of the target autocorrelation result;

[0062] Searching for autocorrelation results of sampling points subsequent to the first sampling point, and if an absolute value of the autocorrelation result of the sampling point subsequent to the first sampling point is greater than an updated target threshold, updating the target threshold using the absolute value of the autocorrelation result of the sampling point subsequent to the first sampling point, until the absolute values of the autocorrelation results of a target number of sampling points are less than or equal to the updated target threshold;

[0063] The position of the first target autocorrelation peak is determined according to the position of the target sampling point corresponding to the updated target threshold value.

[0064] 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 large correlation has been detected. Since the correlation peak has a rising process, the autocorrelation results corresponding to several sampling points located after the first sampling point in the received signal are compared to find the maximum value therein, and the target sampling point position corresponding to the maximum value is determined as the position of the autocorrelation peak, thereby improving the accuracy of determining the autocorrelation peak.

[0065] In a second aspect, the present application provides a power line carrier signal synchronization device based on an OFDMA system, the device comprising:

[0066] a processing module, configured to 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;

[0067] an analysis module, configured to analyze a position of a first target autocorrelation peak in the received signal based on the target autocorrelation result; the first target autocorrelation peak being the autocorrelation peak with the largest peak value in the received signal;

[0068] a first determining module, configured to determine a first window including the first target autocorrelation peak according to a position of the first target autocorrelation peak;

[0069] The second determining module is configured to determine a synchronization peak position in the received signal based on a position of an autocorrelation peak in the first window.

[0070] The power line carrier signal synchronization device based on the OFDMA system provided in the embodiment of the present application analyzes and processes the received signal and the reference sequence through cross-correlation calculation, combines the cross-correlation and autocorrelation methods, can more comprehensively capture the characteristics of the signal, and 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 by the position of the first target autocorrelation peak, which narrows the analysis range of signal synchronization, and the position of the autocorrelation peak in the first window is combined to determine the starting position of the data frame in the received signal, 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.

[0071] In a third aspect, the present application provides a power line carrier signal synchronization system based on an OFDMA system, comprising:

[0072] a signal sending device, used for sending signals;

[0073] A signal receiving device is used to execute the power line carrier signal synchronization method based on the OFDMA system as described in the first aspect above.

[0074] In a fourth aspect, the present application provides an electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the power line carrier signal synchronization method based on the OFDMA system as described in the first aspect above is implemented.

[0075] In a fifth aspect, the present application provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the power line carrier signal synchronization method based on the OFDMA system as described in the first aspect above.

[0076] 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 the OFDMA system as described in the first aspect above.

[0077] The above one or more technical solutions in the embodiments of the present application have at least one of the following technical effects:

[0078] The power line carrier signal synchronization method based on the OFDMA system provided in the embodiment of the present application analyzes and processes the received signal and the reference sequence, combines the cross-correlation and autocorrelation methods, and can more comprehensively capture the characteristics of the signal and improve 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 by the position of the first target autocorrelation peak, which narrows the analysis range of signal synchronization, and the position of the autocorrelation peak in the first window is combined to determine the starting position of the data frame in the received signal, 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.

[0079] Furthermore, considering that in the OFDMA system, multiple users will cause time delay and multipath effect, the autocorrelation results during synchronization will have peaks with different energies within a certain interval. At the same time, the influence of superimposed noise will cause the maximum autocorrelation peak to not necessarily be a valid autocorrelation peak. By performing signal-to-noise ratio detection on the first window during the synchronization process, the signal quality can be accurately identified, thereby accurately judging whether the first target autocorrelation peak is a valid peak.

[0080] Furthermore, considering that the multipath effect and the superposition of noise energy have a significant impact on the peak value of the autocorrelation peak, the signal-to-noise ratio of the first window is detected 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 autocorrelation peak is a valid autocorrelation peak, thereby reducing the influence of noise and improving the accuracy of signal synchronization.

[0081] Furthermore, considering that noise energy superimposed on multipath effects has a significant impact on the autocorrelation peak, a second window excluding the autocorrelation peak is searched based on the position of the first target autocorrelation peak. Since the second window does not include the autocorrelation peak, it can be considered that the received signal in the second window is mainly composed of noise. The average noise energy in the second window is used as the average noise energy in the first window, which can reduce the influence of noise energy and make the calculation of the signal-to-noise ratio more accurate.

[0082] Furthermore, 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 characteristic area of the signal, reduce misjudgment caused by noise or interference in a complex signal environment, better utilize the autocorrelation characteristics of the signal, accurately locate the synchronization peak position, and improve the accuracy of signal synchronization.

[0083] Furthermore, 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 maximum peak position from the true synchronization point is reduced, and the accuracy of signal synchronization is improved.

[0084] Furthermore, by using the autocorrelation peak whose peak meets the target requirements as a reference to determine the synchronization peak position 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.

[0085] Furthermore, 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, thereby improving the accuracy of signal synchronization.

[0086] Furthermore, by comprehensively considering the position information of multiple autocorrelation peaks and adopting the average value or weighted average value, the synchronization deviation caused by the error or noise of a single autocorrelation peak can be reduced. The introduction of the weighted average value can assign different weights according to the intensity or other characteristics of the autocorrelation peak, thereby more accurately locating the synchronization peak position.

[0087] Furthermore, by comparing the signal sequence in the current sliding window of the received signal with the reference sequence through cross-correlation calculation, 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.

[0088] Furthermore, 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 greater correlation has been detected. Since the correlation peak has a rising process, the autocorrelation results corresponding to several sampling points located after the first sampling point in the received signal are compared to find the maximum value therein, and the target sampling point position corresponding to the maximum value is determined as the position of the autocorrelation peak, thereby improving the accuracy of determining the autocorrelation peak.

[0089] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0091] Figure 1This is a graph of autocorrelation simulation results in the presence of noise in an OFDM system provided by an embodiment of the present application;

[0092] Figure 2 This is a graph of autocorrelation simulation results in the presence of noise in an OFDMA system provided by an embodiment of the present application;

[0093] Figure 3 1 is a flow chart of a power line carrier signal synchronization method based on an OFDMA system provided in an embodiment of the present application;

[0094] Figure 4 is a schematic diagram of a first window and a second window provided in an embodiment of the present application;

[0095] Figure 5 This is a structural diagram of a power line carrier signal synchronization device based on an OFDMA system provided in an embodiment of the present application;

[0096] Figure 6 It is a structural diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0097] The following will be combined with the accompanying drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0098] The terms "first," "second," and the like in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of this application can be implemented in an order other than that illustrated or described herein, and that the objects distinguished by "first," "second," and the like are generally of the same type, and do not limit the number of objects; for example, the first object can be one or more. In addition, the term "and / or" in the specification and claims refers to at least one of the connected objects, and the character " / " generally indicates that the objects connected are in an "or" relationship.

[0099] Power Line Communication (PLC) is a communications technology that uses existing power lines as a data transmission medium. High-Speed Power Line Communication (HPLC) is a high-speed communication technology based on PLC, using AC power lines as the physical medium for signal transmission. HPLC offers wider bandwidth and higher data rates, reaching Mbps levels. It also exhibits lower noise and interference at higher frequencies, resulting in improved performance and reliability. Broadband Power Line Communication (BPLC), also an important form of PLC, has a bandwidth limited to 2 to 30 MHz and communication rates typically exceeding 1 Mbps.

[0100] OFDM is a highly efficient digital modulation technology 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. Because the subcarriers are mutually orthogonal, the receiver can recover the information of each subcarrier without distortion. OFDM technology can effectively cope with complex and changing channel environments, improving communication reliability and transmission rates. A notable 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. Different users can only occupy different time slots.

[0101] To better support multi-user communications, OFDMA technology emerged. OFDMA is a multi-user extension of OFDM technology, effectively addressing OFDM's limitations in multi-user scenarios. Unlike OFDM, OFDMA allows different subcarriers to be allocated to multiple users within a time slot, with each user occupying only one or more subcarriers, enabling shared communication among multiple users within the same time slot. Using OFDMA, power line carrier communication systems can better support multi-user access and meet the diverse communication needs of smart grids.

[0102] However, in real-world communication environments, signals travel through multiple different paths during transmission to the receiver. These paths vary in length, and the signal attenuation and propagation delay along each path also vary, creating a multipath effect. The signal received by the receiver is a superposition of multiple attenuated and delayed signals. This not only affects the position and shape of the synchronization peak but also disperses the peak's energy, causing the maximum peak position of the received signal to deviate from the true synchronization peak. Consequently, the maximum peak position may not be the true synchronization peak. Failure to accurately determine the synchronization peak can lead to signal misjudgment and demodulation errors, compromising the performance and reliability of the communication system.

[0103] Figure 1 This is the autocorrelation simulation result diagram when there is noise in the OFDM system, such as Figure 1 As shown, in the OFDM system, the peak position is relatively obvious. Generally, the maximum peak position is the synchronization peak position, and the synchronization peak-to-peak value is significantly larger than the autocorrelation results of sampling points at other positions, and the peak position is relatively sharp. Figure 2 This is the autocorrelation simulation result diagram when there is noise in the OFDMA system. Figure 2 As shown, in the OFDMA system, the noise superposition multipath effect makes the autocorrelation peak not obvious, and the autocorrelation results of the sampling points fluctuate greatly. At this time, the difference between the maximum peak position and the autocorrelation results of other sampling points is not obvious. The present application determines the first window by the maximum peak position, and then combines the signal-to-noise ratio of the first window to accurately judge whether the maximum peak position is a valid peak; at the same time, the influence of noise is removed in the signal-to-noise ratio judgment process, thereby improving the accuracy of the valid peak judgment; when the maximum peak is a valid peak, the synchronization peak position is finally determined according to the autocorrelation peak position in the first window, thereby taking into account the time delay influence caused by the multipath effect and obtaining an accurate synchronization peak position.

[0104] The power line carrier signal synchronization and apparatus based on the OFDMA system provided by the embodiment of the present application will be described in detail below with reference to the accompanying drawings through specific embodiments and their application scenarios.

[0105] 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.

[0106] The terminal includes, but is not limited to, a portable communication device such as a mobile phone or tablet computer having a touch-sensitive surface (e.g., a touch screen display and / or a touch pad). It should also be understood that in some embodiments, the terminal may not be a portable communication device, but rather a desktop computer having a touch-sensitive surface (e.g., a touch screen display and / or a touch pad).

[0107] In 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.

[0108] The embodiment of the present application provides a power line carrier signal synchronization method based on an OFDMA system. The execution subject of the method can be an electronic device or a functional module or functional entity in the electronic device that can implement the method. The electronic devices mentioned in the embodiment of the present application include but are not limited to mobile phones, tablets, computers, cameras and wearable devices. The power line carrier signal synchronization method based on an OFDMA system provided in the embodiment of the present application is described below using an electronic device as an example of the execution subject.

[0109] Figure 3 FIG. 1 is a flow chart of a power line carrier signal synchronization method based on an OFDMA system provided in an embodiment of the present application. Figure 3 As shown, the power line carrier signal synchronization method based on the OFDMA system includes: step 310, step 320, step 330 and step 340.

[0110] 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.

[0111] Signal synchronization refers to the process by which the receiver and transmitter maintain consistency in time, frequency, and phase within a communication system. In a communication system, the transmitter sends signals according to a specific timing structure, while the receiver must accurately identify the starting point, symbol boundaries, frequency, and phase information of the received signal to correctly demodulate and decode the signal.

[0112] During communications, signals are typically transmitted in the form of data frames. Data frames are the basic transmission unit of signals and contain synchronization information, control information, and user data. To correctly receive and process these data frames, the receiver must align time, frequency, and phase with the transmitter, which necessitates signal synchronization. The starting position of a data frame serves as a reference point during synchronization. By determining the location of the synchronization peak, the receiver can accurately locate the starting position of the data frame. Furthermore, the receiver can use this starting position to determine the data symbols, thereby correctly demodulating and interpreting the information in the data frame, achieving reliable data transmission.

[0113] In the embodiments of the present application, a reference sequence is a pre-known signal sequence with specific characteristics. In power line carrier communication, the reference sequence is typically pre-agreed upon by both the transmitter and receiver. The design of the reference sequence must meet certain specific requirements, such as having good autocorrelation and cross-correlation characteristics. The length of the reference sequence can be the interval length between the start positions of different data frames in the received signal, for example, a length covering 1024 sampling points.

[0114] Cross-correlation measures the correlation between a received signal sequence and a known signal sequence. It can typically be determined by calculating the sum of the products of one signal and another at different time delays. Autocorrelation measures the correlation between a signal and its own values at different time delays. If a time series exhibits strong autocorrelation at a certain time delay, it indicates that the sequence exhibits a certain degree of repetitiveness or periodicity at that delay.

[0115] Therefore, a cross-correlation operation can be first performed on the received signal and a known reference sequence to obtain a cross-correlation result. Each time a cross-correlation result is calculated, it can be stored. Subsequently, an autocorrelation operation can be performed on the cross-correlation result and the cross-correlation result obtained by historical calculation to obtain an autocorrelation result.

[0116] In some embodiments, performing cross-correlation processing on the received signal and the reference sequence to obtain a target cross-correlation result includes:

[0117] A signal sequence in the received signal located in the current sliding window is cross-correlated with a reference sequence to obtain a target cross-correlation result; the target cross-correlation result is a cross-correlation result of a first sampling point; the first sampling point is located in the signal sequence in the current sliding window.

[0118] In this embodiment, the sampling points are discrete representations of the received signal in terms of time and amplitude, and the sampling points carry 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.

[0119] A sliding window is an analysis window that can be moved across the received signal to analyze the signal's characteristics segment by segment. The sliding window's length is the same as the length of the reference sequence. The sliding window can slide across the received signal in a preset step size, for example, one sample point, two samples, or another number of samples. The current sliding window is the current position of the sliding window.

[0120] In this embodiment, a cross-correlation calculation may be performed on the signal sequence within the current sliding window and the reference sequence to obtain a cross-correlation result at a first sampling point. The first sampling point may be a specific sampling point within the current sliding window, and the relative position of the specific sampling point within the sliding window is fixed. For example, the specific sampling point may be the first sampling point, the second sampling point, or a sampling point at another position within the sliding window.

[0121] In some embodiments, performing cross-correlation calculation on a signal sequence in a received signal located within a current sliding window and a reference sequence to obtain a target cross-correlation result includes:

[0122] Calculate the sign coefficient corresponding to each sampling point based on the signal amplitude corresponding to each sampling point in the signal sequence within the current sliding window; wherein the positive and negative signs of the signal amplitude are consistent with the positive and negative signs of the sign coefficient;

[0123] The signal sequence in the current sliding window is multiplied with the symbol coefficients corresponding to the sampling points at the same position in the reference sequence, and the multiplication results of each sampling point are summed to obtain the target cross-correlation result.

[0124] In related technologies, calculation of cross-correlation results usually requires multiplying and then adding the signal amplitudes of two signals at different sampling points, which is computationally complex.

[0125] In this embodiment, the calculation of the cross-correlation result can take the sign coefficient of the signal amplitude, and calculate the cross-correlation result by multiplying and adding the sign coefficients, thereby simplifying the calculation process, improving the calculation efficiency, and retaining the basic characteristics of the signal.

[0126] Specifically, both the signal sequence and the reference sequence within the current sliding window contain multiple sampling points, each of which has a corresponding signal amplitude. The signal amplitude is the instantaneous value of the sampling point and can be positive, negative, or zero. The signal amplitude reflects the strength and direction of the signal at different time points.

[0127] For each sampling point, a sign coefficient is determined based on the sign of the signal amplitude. The sign coefficient is a simple marker that indicates the direction of the signal amplitude. If the signal amplitude is positive, the sign coefficient is +1; if the signal amplitude is negative, the sign coefficient is -1; and if the signal amplitude is zero, the sign coefficient is 0.

[0128] For example, the signal sequence in the current sliding window is ,in, For the The signal amplitude of the sampling points, the corresponding symbol coefficient is ,in, For the The symbol coefficients of the sampling points:

[0129] ,

[0130] 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 position 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.

[0131] For example, the symbol coefficient corresponding to the current sliding window is , the symbol coefficient corresponding to the reference sequence is , The reference sequence The symbol coefficients of the sampling points, then the cross-correlation result of the first sampling point is It can be expressed as:

[0132] ,

[0133] In this embodiment, the sign coefficient of each sampling point is determined based on the signal amplitude corresponding to each sampling point in the signal sequence within the current sliding window. The positive and negative signs of the signal amplitude are kept consistent with the positive and negative signs of the sign coefficient, so that no complex multiplication operations are required in the cross-correlation calculation, which simplifies the calculation process and reduces the calculation complexity.

[0134] 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:

[0135] The target cross-correlation result and the target historical cross-correlation result are autocorrelated 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.

[0136] 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. 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 points within the sliding window.

[0137] 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 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.

[0138] In some embodiments, performing autocorrelation calculation on the target cross-correlation result and the target historical cross-correlation result to obtain the target autocorrelation result includes:

[0139] The cross-correlation result of the first sampling point is multiplied by the cross-correlation result of the second sampling point to obtain a target autocorrelation result.

[0140] Because the cross-correlation peak may vary in different noise environments and may not be obvious, this embodiment performs autocorrelation on the basis of 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, a more obvious correlation peak can be obtained.

[0141] 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.

[0142] Related technologies typically calculate the cross-correlation between the signal and the local sequence, using the cross-correlation peak to determine the synchronization peak. This approach can achieve effective synchronization under ideal channel conditions, but strong noise interference (such as narrowband interference and background noise) and low signal-to-noise ratio (SNR) in power line channels can significantly reduce the significance of correlation peaks. For example, bursts of impulse noise in power lines can cause false correlation peaks, leading to misjudgment. In low SNR conditions, the cross-correlation peak is less pronounced, also making misjudgment more likely.

[0143] In this embodiment, a signal sequence in the received signal within the current sliding window is compared with a reference sequence through cross-correlation calculation, so that similarity between the signal sequence and the reference sequence can be identified. An autocorrelation calculation is performed on the obtained cross-correlation result of the first sampling point 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. By combining the cross-correlation and autocorrelation methods, the characteristics of the signal can be more comprehensively captured, thereby improving the accuracy of autocorrelation peak detection.

[0144] 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.

[0145] When there is a large correlation between the received signal and the reference, the autocorrelation results obtained in combination with the history will show a peak shape in the data distribution, that is, the autocorrelation peak.

[0146] The peak value of the autocorrelation peak can be represented by the autocorrelation result of the sampling point. When the autocorrelation result of a sampling point is greater than a preset threshold, the location of the sampling point can be considered to be the location of the autocorrelation peak. Furthermore, by comparing the autocorrelation results of multiple sampling points, the autocorrelation peak with the largest peak value can be found, i.e., the first target autocorrelation peak.

[0147] In some embodiments, analyzing a position of a first target autocorrelation peak in the received signal based on the target autocorrelation result includes:

[0148] When the absolute value of the target autocorrelation result is greater than the target threshold value, the target threshold value is updated using the absolute value of the target autocorrelation result;

[0149] Searching the autocorrelation results of the sampling points after the first sampling point, and if the absolute value of the autocorrelation result of the sampling point after the first sampling point is greater than the updated target threshold value, updating the target threshold value by using the absolute value of the autocorrelation result of the sampling point after the first sampling point, until the absolute value of the autocorrelation result of the target number of sampling points is less than or equal to the updated target threshold value;

[0150] The position of the first target autocorrelation peak is determined according to the position of the target sampling point corresponding to the updated target threshold value.

[0151] In this embodiment, the target threshold is a preset threshold value that can be used to determine whether the autocorrelation result is large enough, thereby determining 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.

[0152] 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 based on 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.

[0153] Because the autocorrelation peak rises, the first sampling point may be located at the foot or waist of the peak. Therefore, the peak location can be searched by dynamically adjusting the target threshold. Specifically, if the absolute value of the target autocorrelation result is greater than the target threshold, the target threshold is updated using the absolute value of the target autocorrelation result. The autocorrelation results of sampling points after the first sampling point are searched. If the absolute value of the autocorrelation result of the searched sampling point is greater than the updated target threshold, the absolute value of the autocorrelation result of the searched sampling point is used as the new target threshold. The search continues backward until the target threshold stabilizes. For example, the search continues backward until a target number of sampling points are found, and the autocorrelation results of these sampling points are all less than or equal to the target threshold. The target number can be 15, 20, 30, 50, 60, or any other number. The target number can be set based on the signal characteristics and the expected autocorrelation peak width. For example, if the expected autocorrelation peak is wide, the target number can be set larger; if the expected autocorrelation peak is narrow, the target number can be set smaller.

[0154] 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 the absolute value of the autocorrelation result of the a-th sampling point is updated to the target threshold value, the search for a target number of sampling points is continued backward. 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 of the a-th sampling point can be determined as the position of the autocorrelation peak.

[0155] 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 large correlation has been detected. Since the correlation peak has a rising process, the autocorrelation results corresponding to several sampling points located after the first sampling point in the received signal are compared to find the maximum value therein, and the target sampling point position corresponding to the maximum value is determined as the position of the autocorrelation peak, thereby improving the accuracy of determining the autocorrelation peak.

[0156] Step 330: Determine a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak.

[0157] In an embodiment of the present application, a specific interval, i.e., a first window, can be defined based on the position of the first target autocorrelation peak. The size and position of the first window can be determined based on 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 to both sides within a certain range, or the first target autocorrelation peak can be located at any position within the first window.

[0158] In some embodiments, determining a first window including the first target autocorrelation peak according to a position of the first target autocorrelation peak includes:

[0159] determining a first target length of the first window;

[0160] A range centered at the position of the target autocorrelation peak and having a length equal to a first target length is determined as a first window.

[0161] In this embodiment, the first target length may be pre-set or determined based on the characteristics of the received signal. For example, if the received signal has a very clear periodicity and high synchronization requirements, the first target length may 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 periodicity of the signal is less obvious, a longer first target length may be set to include more signal characteristics, thereby improving synchronization reliability.

[0162] After determining the first target length, a range centered at the position of the target autocorrelation peak and having a length equal to 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. For example, if the first target length is 40 sampling points, that is, in addition to the sampling points corresponding to the first target correlation peak, the length of the first window also covers 40 sampling points. The range of the 20 sampling points before and the 20 sampling points after 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, which is not limited in the embodiments of the present application.

[0163] 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, the key feature area of the signal can be focused, thereby reducing misjudgment caused by noise or interference in a complex signal environment, and better utilizing the autocorrelation characteristics of the signal to accurately locate the synchronization peak position, thereby improving the accuracy of signal synchronization.

[0164] In some embodiments, determining the first target length of the first window includes:

[0165] Obtain the maximum delay of the received signal along multiple different paths;

[0166] The first target length is determined according to the maximum delay and the sampling rate of the received signal.

[0167] During communications, received signals typically propagate along multiple different paths of varying length, resulting in varying arrival times. The maximum propagation delay of the received signal along these paths can be determined, and the first target length can be determined based on the maximum delay and the received signal sampling rate. For example, if the maximum delay is 4 μs and the sampling rate is 20 MHz (i.e., a sampling interval of 50 ns), the first target length is 4 × 20 = 80, or 80 sampling points. The first window can be the range of 40 points before and after the first target correlation peak.

[0168] In this embodiment, the maximum delay reflects the time difference of the signal propagating on different paths, and the sampling rate determines the degree of temporal discretization of the signal. By combining the maximum delay with the sampling rate, the length of the first window determined can enable the first window to cover the key characteristic area of the signal and include as many correlation peaks of effective multipath components as possible, making the determination of the synchronization peak position more accurate.

[0169] Step 340: Determine the position of the synchronization peak in the received signal based on the position of the autocorrelation peak in the first window.

[0170] Considering that in the OFDMA system, multiple users will cause time delay and multipath effect, resulting in the autocorrelation result during synchronization having peaks with different energies within a certain interval, and the influence of superimposed noise, the maximum autocorrelation peak is not necessarily a valid autocorrelation peak. Therefore, before determining the synchronization peak position in the received signal based on the position of the autocorrelation peak in the first window, it is necessary to determine whether the first target autocorrelation peak is a valid peak.

[0171] In some embodiments, determining a synchronization peak position in the received signal based on a position of an autocorrelation peak in the first window includes:

[0172] Determining whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the first window;

[0173] In the case where the first target autocorrelation peak is a valid peak, the synchronization peak position in the received signal is determined based on the position of the autocorrelation peak in the first window.

[0174] Since the multipath effect and noise energy have a significant impact on the autocorrelation peak, in order to determine whether the first target autocorrelation peak is a valid peak, that is, a false peak not caused by noise, the signal-to-noise ratio of the first window can be used to determine whether the first target autocorrelation peak is a valid peak.

[0175] In this embodiment, by performing signal-to-noise ratio detection on the first window during the synchronization process, the signal quality can be accurately identified, thereby accurately determining whether the first target autocorrelation peak is a valid peak.

[0176] 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:

[0177] Calculate the signal-to-noise ratio of the first window;

[0178] When the signal-to-noise ratio is greater than the target signal-to-noise ratio threshold, the first target autocorrelation peak is determined to be a valid peak.

[0179] In this embodiment, the signal-to-noise ratio of the first window can be calculated. When the signal-to-noise ratio is greater than the target signal-to-noise ratio threshold, it indicates that the signal reliability is high and is less affected by noise. It is determined that the first target autocorrelation peak is a valid peak, and the position of the synchronization peak in the received signal can be determined based on the position of the autocorrelation peak in the first window.

[0180] Considering that in the absence of multipath, the validity of the maximum peak is determined by whether its SNR exceeds the target SNR threshold, the target SNR threshold is set relatively high. In the presence of multipath, the SNR of the maximum peak decreases, so a relatively low target SNR threshold is required. Determining the validity of the maximum peak based on the SNR within the first window can reduce the impact of multipath and noise, improving signal synchronization accuracy.

[0181] In some embodiments, calculating the signal-to-noise ratio of the first window includes:

[0182] searching a second window having a second target length based on the position of the first target autocorrelation peak; the second window does not include the autocorrelation peak;

[0183] Determine the average value of the autocorrelation results of the sampling points of the received signal in the second window as the average noise energy in the second window;

[0184] The average noise energy in the second window is used as the average noise energy in the first window, and the average signal energy of the first window excluding noise is calculated in combination with the autocorrelation results of the sampling points of the received signal in the first window;

[0185] The ratio of the average energy of the signal to the average energy of the noise is determined as the signal-to-noise ratio.

[0186] In this embodiment, noise is a random interference component in a signal that masks the true characteristics of the signal. Noise average energy refers to the energy average of the noise component in the signal.

[0187] To accurately estimate the average energy of the noise, a second window may be searched according to the position of the first target autocorrelation peak. The second window may be a position before or after the first target autocorrelation peak in the received signal, and the second window does not include the autocorrelation peak.

[0188] 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 fixed in theory, for example, the interval is fixed to 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, such as Figure 4 As shown, in the second window, there is no autocorrelation peak.

[0189] Since the second window does not contain an autocorrelation peak, it can be assumed that the signal component in the second window is mainly composed of noise. The autocorrelation results of all sampling points in the second window can be averaged to obtain the noise average energy. In other words, the noise average energy is the average of the autocorrelation results of the sampling points in the second window.

[0190] 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 the noise characteristics in the first window, so the average noise energy in the second window can be used to represent the noise level in the first window.

[0191] In this embodiment, the signal average energy within the first window can be calculated based on the noise average energy. Specifically, the signal energy within the first window can be obtained by subtracting the average energy of the noise from the autocorrelation result of each sampling point in the first window. The signal energy within the first window is then accumulated and averaged to obtain the signal average energy. Specifically, the signal energy within the first window can be obtained by subtracting the average energy of the noise from the autocorrelation result of each sampling point in the first window. The signal energy within the first window is then accumulated and averaged to obtain the signal average energy.

[0192] In some embodiments, the formula:

[0193] ,

[0194] Calculating the average energy of the signal;

[0195] in, represents the average energy of the signal in the first window excluding the noise signal, Indicates the sampling point in the first window The autocorrelation results of represents the number of sampling points in the first window, Represents the average noise energy in the second window.

[0196] In this embodiment, considering that the noise energy superimposed on the multipath effect has a significant impact on the autocorrelation peak, a second window that does not include the autocorrelation peak is searched according to the position of the first target autocorrelation peak. Since the second window does not include the autocorrelation peak, it can be considered that the received signal in the second window is mainly composed of noise. The average noise energy in the second window is used as the average noise energy in the first window, which can reduce the impact of the noise energy and make the calculation of the signal-to-noise ratio more accurate. Figure 4It can be seen that the energy in the first window is affected by the multipath effect and the noise energy, resulting in that the autocorrelation result in the first window is not much different from the autocorrelation result in the second window. In the embodiment of the present application, the energy in the second window is subtracted from the energy in the first window, thereby reducing the influence of noise on the signal-to-noise ratio in the first window, so that the calculated signal-to-noise ratio is more accurate. Further, it can be accurately judged whether the autocorrelation peak in the first window is a valid peak, thereby reducing misjudgment and improving the accuracy of judgment.

[0197] In the embodiment of the present application, the autocorrelation peak position information in the first window can be used to determine the synchronization peak position in the received signal. Figure 4 As shown, in the first window, in addition to the first target autocorrelation peak, there are other autocorrelation peaks, wherein the first target autocorrelation peak is the autocorrelation peak with the largest peak value in the first window.

[0198] In some embodiments, the average of the positions of multiple autocorrelation peaks in the first window can be determined as the synchronization peak position in the received signal. The synchronization peak position in the received signal can also be determined by other means. For example, weights can be assigned based on the peak values of different autocorrelation peaks, with higher weights assigned to higher peak values. The positions of the multiple autocorrelation peaks are then weighted averaged, and the weighted average is determined as the synchronization peak position in the received signal. Of course, the synchronization peak position in the received signal can also be determined based on the positions of the autocorrelation peaks in the first window by other means, and this embodiment of the present application is not limited thereto.

[0199] In some embodiments, determining a synchronization peak position in the received signal based on a position of an autocorrelation peak in the first window includes:

[0200] Acquire 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;

[0201] The synchronization peak position in the received signal is determined according to the positions of the plurality of second target autocorrelation peaks.

[0202] In this embodiment, the first window includes multiple autocorrelation peaks. For example, the peak values of these autocorrelation peaks are greater than the initial peak threshold. The multiple autocorrelation peaks in the first window can be screened to obtain multiple second target autocorrelation peaks; the multiple second target autocorrelation peaks include at least the first target autocorrelation peak.

[0203] 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 maximum peak position deviating from the true synchronization point is reduced, and the accuracy of signal synchronization is improved.

[0204] In some embodiments, the second target autocorrelation peak is an autocorrelation peak whose peak value meets the target requirement among the autocorrelation peaks in the first window.

[0205] In this embodiment, the synchronization peak position in the received signal is determined by taking the autocorrelation peak whose peak value meets the target requirements as a reference, and 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.

[0206] In this embodiment, the higher the peak value of the autocorrelation peak, the more significant the periodicity or repeatability of the position of the autocorrelation peak corresponding to the received signal, and the more likely it is to be the synchronization peak position. Therefore, the target requirement can be the n autocorrelation peaks with the largest peak values among the autocorrelation peaks in the first window, for example, n can be 2, 3, 4, 5 or other numbers. The target requirement can also be the autocorrelation peaks with a peak value greater than the target threshold among the autocorrelation peaks in 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 a 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 in the first window, thereby improving the accuracy of signal synchronization.

[0207] In some embodiments, determining a synchronization peak position in a received signal based on positions of a plurality of second target autocorrelation peaks includes:

[0208] Calculating an average or weighted average of positions of a plurality of second target autocorrelation peaks;

[0209] The average value or the weighted average value is determined as the synchronization peak position in the received signal.

[0210] In this embodiment, the position information of multiple second target autocorrelation peaks may be used to calculate the average value of these positions, and the average value may be determined as the synchronization peak position in the received signal.

[0211] Different weights may also be assigned according to the peak values or other characteristics of the second target correlation peaks, and then a weighted average value of the positions is calculated, and the weighted average value is determined as the synchronization peak position in the received signal.

[0212] In this embodiment, by comprehensively considering the position information of multiple autocorrelation peaks and adopting the average value or weighted average value, the synchronization deviation caused by the error or noise influence of a single autocorrelation peak can be reduced. The introduction of the weighted average value can assign different weights according to the intensity or other characteristics of the autocorrelation peak, thereby more accurately locating the synchronization peak position.

[0213] According to one embodiment of the present application, determining an average value or a weighted average value of positions of a plurality of second target autocorrelation peaks includes:

[0214] determining sampling points corresponding to a plurality of second target autocorrelation peaks;

[0215] The sampling point positions corresponding to the plurality of second target autocorrelation peaks are used as the positions of the plurality of second target autocorrelation peaks, and an average value or a weighted average value is determined.

[0216] In this embodiment, the position of the autocorrelation peak can be represented by a sampling point. 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 the autocorrelation peak, and the position of the autocorrelation peak is the position of the 10th sampling point.

[0217] In this embodiment, an average value or weighted average value can be determined by using the positions of the sampling points corresponding to the multiple second target autocorrelation peaks as the positions of the multiple second target autocorrelation peaks. For example, if the first window includes three second target autocorrelation peaks, and the corresponding sampling points are located at positions X1, X2, and X3, respectively, and the average value is determined to be (X1+X2+X3) / 3, then the position of the synchronization peak in the received signal is (X1+X2+X3) / 3.

[0218] In this embodiment, the position of the autocorrelation peak is identified by the sampling point positions, and an average value or a weighted average value is calculated based on the positions of these sampling points, so that the synchronization peak position can be accurately located.

[0219] The power line carrier signal synchronization method based on the OFDMA system provided in the embodiment of the present application analyzes and processes the received signal and the reference sequence, combines the cross-correlation and autocorrelation methods, and can more comprehensively capture the characteristics of the signal and improve 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 by the position of the first target autocorrelation peak, which narrows the analysis range of signal synchronization, and the position of the autocorrelation peak in the first window is combined to determine the starting position of the data frame in the received signal, 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.

[0220] The power line carrier signal synchronization method based on an OFDMA system provided in the embodiments of the present application can be executed by a power line carrier signal synchronization device based on an OFDMA system. In the embodiments of the present application, the power line carrier signal synchronization method based on an OFDMA system is executed by a power line carrier signal synchronization device based on an OFDMA system as an example to illustrate the power line carrier signal synchronization device based on an OFDMA system provided in the embodiments of the present application.

[0221] An embodiment of the present application also provides a power line carrier signal synchronization device based on an OFDMA system.

[0222] Figure 5 FIG. 1 is a schematic diagram of a power line carrier signal synchronization device based on an OFDMA system provided in an embodiment of the present application. Figure 5 As shown, the power line carrier signal synchronization device based on the OFDMA system includes:

[0223] The processing module 510 is configured to 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;

[0224] An analysis module 520 is configured to analyze a 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;

[0225] A first determining 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;

[0226] The second determining module 540 is configured to determine a synchronization peak position in the received signal based on a position of an autocorrelation peak in the first window.

[0227] The power line carrier signal synchronization device based on the OFDMA system provided in the embodiment of the present application analyzes and processes the received signal and the reference sequence, combines the cross-correlation and autocorrelation methods, and can more comprehensively capture the characteristics of the signal, thereby improving 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 by the position of the first target autocorrelation peak, which narrows the analysis range of the signal synchronization, and the position of the autocorrelation peak in the first window is combined to determine the starting position of the data frame in the received signal, thereby reducing the synchronization error caused by the deviation of the maximum peak position from the true synchronization point, thereby improving the accuracy of signal synchronization.

[0228] In some embodiments, the second determining module 540 is further configured to:

[0229] Determining whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the received signal in the first window;

[0230] In the case where the first target autocorrelation peak is a valid peak, the synchronization peak position in the received signal is determined based on the position of the autocorrelation peak in the first window.

[0231] In some embodiments, the second determining module 540 is further configured to:

[0232] Calculating the signal-to-noise ratio of the received signal in the first window;

[0233] When the signal-to-noise ratio is greater than the target signal-to-noise ratio threshold, the first target autocorrelation peak is determined to be a valid peak.

[0234] In some embodiments, the second determining module 540 is further configured to:

[0235] searching the received signal for a second window having a second target length based on the position of the first target autocorrelation peak; the second window does not include the autocorrelation peak;

[0236] Determine the average value of the autocorrelation results of the sampling points of the received signal in the second window as the average noise energy in the second window;

[0237] The noise average energy in the second window is used as the noise average energy in the first window, and the signal average energy of the received signal in the first window excluding noise is calculated in combination with the autocorrelation results of the sampling points of the received signal in the first window;

[0238] The ratio of the average energy of the signal to the average energy of the noise is determined as the signal-to-noise ratio.

[0239] In some embodiments, the second determining module 540 is further configured to:

[0240] According to the formula:

[0241] ,

[0242] Calculating the average energy of the signal;

[0243] in, represents the average energy of the signal in the first window excluding the noise signal, Indicates the sampling point in the first window The autocorrelation results of represents the number of sampling points in the first window, Represents the average noise energy in the second window.

[0244] In some embodiments, the first determining module 530 is further configured to:

[0245] determining a first target length of the first window;

[0246] A range centered at the position of the target autocorrelation peak and having a length equal to a first target length is determined as a first window.

[0247] In some embodiments, the second determining module 540 is further configured to:

[0248] Acquire 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;

[0249] The synchronization peak position in the received signal is determined according to the positions of the plurality of second target autocorrelation peaks.

[0250] In some embodiments, the second determining module 540 is further configured to:

[0251] Calculating an average or weighted average of positions of a plurality of second target autocorrelation peaks;

[0252] The average value or the weighted average value is determined as the synchronization peak position in the received signal.

[0253] In some embodiments, the second determining module 540 is further configured to:

[0254] determining sampling points corresponding to a plurality of second target autocorrelation peaks;

[0255] The positions of the sampling points corresponding to the plurality of second target autocorrelation peaks are used as the positions of the plurality of second target autocorrelation peaks, and an average value or a weighted average value is determined.

[0256] In some embodiments, the processing module 510 is further configured to:

[0257] Performing cross-correlation calculation on a signal sequence in the received signal located within the current sliding window and a reference sequence to obtain a target cross-correlation result; the target cross-correlation result is a cross-correlation result of a first sampling point; the first sampling point is located in the signal sequence within the current sliding window;

[0258] The target cross-correlation result and the target historical cross-correlation result are autocorrelated 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.

[0259] In some embodiments, the processing module 510 is further configured to:

[0260] Calculate the sign coefficient corresponding to each sampling point based on the signal amplitude corresponding to each sampling point in the signal sequence within the current sliding window; wherein the positive and negative signs of the signal amplitude are consistent with the positive and negative signs of the sign coefficient;

[0261] The signal sequence in the current sliding window is multiplied with the symbol coefficients corresponding to the sampling points at the same position in the reference sequence, and the multiplication results of each sampling point are summed to obtain the target cross-correlation result.

[0262] In some embodiments, the processing module 510 is further configured to:

[0263] The cross-correlation result of the first sampling point is multiplied by the cross-correlation result of the second sampling point to obtain a target autocorrelation result.

[0264] In some embodiments, the analysis module 520 is further configured to:

[0265] When the absolute value of the target autocorrelation result is greater than the target threshold value, the target threshold value is updated using the absolute value of the target autocorrelation result;

[0266] Searching the autocorrelation results of the sampling points after the first sampling point, and if the absolute value of the autocorrelation result of the sampling point after the first sampling point is greater than the updated target threshold value, updating the target threshold value by using the absolute value of the autocorrelation result of the sampling point after the first sampling point, until the absolute value of the autocorrelation result of the target number of sampling points is less than or equal to the updated target threshold value;

[0267] The position of the first target autocorrelation peak is determined according to the position of the target sampling point corresponding to the updated target threshold value.

[0268] The power line carrier signal synchronization device based on the OFDMA system in the embodiment of the present application can be an electronic device or a component of the electronic device, such as an integrated circuit or chip. The electronic device can be a terminal or other devices other than a terminal. For example, the electronic device can be a mobile phone, a tablet computer, a laptop computer, a PDA, an in-vehicle 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. It 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., and the embodiment of the present application does not specifically limit it.

[0269] The OFDMA-based power line carrier signal synchronization device in the embodiments of the present application may be a device having an operating system. The operating system may be a Microsoft (Windows) operating system, an Android operating system, an iOS operating system, or other possible operating systems, which are not specifically limited in the embodiments of the present application.

[0270] In some embodiments, Figure 6 is a schematic diagram of the structure of the electronic device provided in the embodiment of the present application, such as Figure 6As shown, an embodiment of the present application further provides an electronic device 600, including a processor 601, a memory 602, and a computer program stored in the memory 602 and executable on the processor 601. When the program is executed by the processor 601, the various processes of the above-mentioned embodiment of the power line carrier signal synchronization method based on the OFDMA system are implemented, and the same technical effect can be achieved. To avoid repetition, it will not be described here.

[0271] 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.

[0272] The embodiment of the present application further provides a power line carrier signal synchronization system based on an OFDMA system, comprising:

[0273] a signal sending device, used for sending signals;

[0274] The signal receiving device is used to execute the above-mentioned power line carrier signal synchronization method based on the OFDMA system.

[0275] An 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, the various processes of the above-mentioned embodiment of the power line carrier signal synchronization method based on the OFDMA system are implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0276] The processor is the processor in the electronic device in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory ROM, a random access memory RAM, a magnetic disk or an optical disk.

[0277] An embodiment of the present application further provides a computer program product, including a computer program, which, when executed by a processor, implements the above-mentioned power line carrier signal synchronization method based on the OFDMA system.

[0278] The processor is the processor in the electronic device in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory ROM, a random access memory RAM, a magnetic disk or an optical disk.

[0279] An embodiment of the present application further provides a chip, which includes a processor and a communication interface, the communication interface and the processor are coupled, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned power line carrier signal synchronization method embodiment based on the OFDMA system, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0280] It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0281] It should be noted that, in this article, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, it should be noted 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 the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0282] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better embodiment. Based on this understanding, the technical solution of this application, or the part that contributes to the existing technology, 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 a number of instructions for enabling a terminal (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in each embodiment of this application.

[0283] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the protection of this application.

[0284] Throughout this specification, 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 conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0285] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and intent of the present application, and that 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 OFDMA system, characterized in that: include: 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; 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 a size and position of the first window according to the position of the first target autocorrelation peak and characteristics of the received signal; determining a synchronization peak position in the received signal based on a position of an autocorrelation peak in the first window; The determining of the synchronization peak position in the received signal based on the position of the autocorrelation peak in the first window includes: determining whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the first window; In a case where the first target autocorrelation peak is a valid peak, a synchronization peak position in the received signal is determined based on a position of the autocorrelation peak in the first window.

2. The method according to claim 1, characterized in that The determining 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, the first target autocorrelation peak is determined to be a valid peak.

3. The method according to claim 2, characterized in that The calculating the signal-to-noise ratio of the received signal in the first window includes: Searching for a second window having a second target length based on the position of the first target autocorrelation peak; the second window does not include the autocorrelation peak; Determine an average value of autocorrelation results of sampling points of the received signal in the second window as the average noise energy in the second window; Using the noise average energy in the second window as the noise average energy in the first window, and combining the autocorrelation results of the sampling points of the received signal in the first window to calculate the signal average energy of the received signal in the first window excluding the noise; The ratio of the signal average energy to the noise average energy is determined as the signal-to-noise ratio.

4. The method according to claim 1, wherein The determining a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak comprises: determining a first target length of the first window; A range centered at the position of the target autocorrelation peak and having a length equal to the first target length is determined as the first window.

5. The method according to claim 1, characterized in that The determining the synchronization peak position in the received signal based on the position of the autocorrelation peak in the first window includes: Acquire 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; The synchronization peak position in the received signal is determined according to the positions of the plurality of second target autocorrelation peaks.

6. The method according to claim 5, characterized in that The determining the synchronization peak position in the received signal according to the positions of the plurality of second target autocorrelation peaks includes: Calculating an average or weighted average of the positions of a plurality of second target autocorrelation peaks; The average value or the weighted average value is determined as the synchronization peak position in the received signal.

7. The method according to claim 1, characterized in that The cross-correlation processing of the received signal and the reference sequence to obtain a target cross-correlation result, and the autocorrelation operation of the target cross-correlation result and the target historical cross-correlation result to obtain a target autocorrelation result includes: performing cross-correlation calculation on a signal sequence in the received signal located within the current sliding window and the reference sequence to obtain a target cross-correlation result; the target cross-correlation result is a cross-correlation result of a 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.

8. The method according to claim 7, characterized in that The analyzing a 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 value, updating the target threshold value by using the absolute value of the target autocorrelation result; Searching for autocorrelation results of sampling points subsequent to the first sampling point, and if an absolute value of the autocorrelation result of the sampling point subsequent to the first sampling point is greater than an updated target threshold, updating the target threshold using the absolute value of the autocorrelation result of the sampling point subsequent to the first sampling point, until the absolute values of the autocorrelation results of a target number of sampling points are less than or equal to the updated target threshold; The position of the first target autocorrelation peak is determined according to the position of the target sampling point corresponding to the updated target threshold value.

9. A power line carrier signal synchronization device based on OFDMA system, characterized in that: include: a processing module, configured to 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; an analysis module, configured to analyze a position of a first target autocorrelation peak in the received signal based on the target autocorrelation result; the first target autocorrelation peak being the autocorrelation peak with the largest peak value in the received signal; a first determining module, configured to determine a first window including the first target autocorrelation peak according to the position of the first target autocorrelation peak; the size and position of the first window may be determined according to the position of the first target autocorrelation peak and signal characteristics; A second determining module is configured to determine a synchronization peak position in the received signal based on a position of an autocorrelation peak in the first window; wherein determining the synchronization peak position in the received signal based on the position of the autocorrelation peak in the first window includes: determining whether the first target autocorrelation peak is a valid peak based on the signal-to-noise ratio of the first window; In a case where the first target autocorrelation peak is a valid peak, a synchronization peak position in the received signal is determined based on a position of the autocorrelation peak in the first window.

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