Power line carrier signal synchronization method and device

Abstract

The invention discloses a power line carrier signal synchronization method and device, and belongs to the technical field of power line carrier communication. The method comprises the following steps: under the condition that a signal sequence is received, determining an autocorrelation result based on a known signal sequence; under the condition that the self-correlation result exceeds a dynamic threshold value, determining an effective correlation peak; the dynamic threshold is dynamically updated along with the change trend of the plurality of self-correlation results; and starting signal synchronization under the condition that the effective correlation peak and the historical effective correlation peak form a continuous correlation peak. According to the invention, through combination of cross-correlation and self-correlation, accurate detection of effective correlation peaks is realized, a dynamic threshold and continuity verification mechanism is introduced, the accuracy and robustness of signal synchronization are improved, the synchronization misjudgment rate can be significantly reduced, and the synchronization efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a power line carrier signal synchronization method and device. Background Art

[0002] High-speed Power Line Communication (HPLC) technology is a communication technology that uses power lines for high-speed data transmission. In related technologies, the HPLC system mainly uses the cross-correlation method for time synchronization, which performs cross-correlation calculations on the received signal and a pre-known local reference sequence, and determines the synchronization position based on the peak position of the correlation function.

[0003] However, due to the complex power line channel environment, common background noise, narrowband interference and sudden pulse noise will have a significant impact on the received signal. Under low signal-to-noise ratio conditions, the main peak of the cross-correlation output and the side peak caused by noise are difficult to distinguish, resulting in synchronization failure; and sudden pulse noise may introduce pseudo peaks, leading to misjudgment of the synchronization position. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention proposes a power line carrier signal synchronization method, device, system, chip, equipment and storage medium to achieve high robustness and high precision signal synchronization.

[0005] In a first aspect, the present invention provides a method for synchronizing a power line carrier signal, the method comprising: In case of receiving the signal sequence, determining an autocorrelation result based on the known signal sequence; In the case where the autocorrelation result exceeds a dynamic threshold, determining a valid correlation peak; the dynamic threshold is dynamically updated along with the changing trend of the multiple autocorrelation results; When the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak, signal synchronization is initiated.

[0006] According to the power line carrier signal synchronization method provided by the present invention, by detecting a signal sequence and, in the case of receiving the signal sequence, determining an autocorrelation result based on the known signal sequence, the synchronization feature in the signal can be effectively detected through autocorrelation processing, improving the accuracy and reliability of synchronization detection; in the case where the autocorrelation result exceeds a dynamic threshold, a valid correlation peak is determined, which can eliminate invalid correlation peaks, improving the anti-interference ability of synchronization detection, and adopting a dynamic threshold mechanism based on the changing trend of the autocorrelation result can adaptively update the threshold, making the identification of valid correlation peaks more accurate; and in the case where the valid correlation peak and the historical valid correlation peak form a continuous correlation peak, by detecting the continuous correlation peaks, the stability and consistency of the synchronization signal are ensured, thereby reliably starting the signal synchronization process, reducing the possibility of misjudgment and missed judgment, achieving efficient and accurate synchronization of signals in a complex channel environment, and enhancing the robustness and reliability of signal synchronization.

[0007] According to an embodiment of the present invention, the determining a valid correlation peak in the case where the autocorrelation result exceeds a dynamic threshold includes: in the case where the autocorrelation result exceeds a dynamic threshold, determining the maximum correlation peak; the peak value of the maximum correlation peak is the current autocorrelation result, and the peak position is the signal position of the sampling point corresponding to the peak; verifying the validity of the maximum correlation peak, and in the case where the validity verification passes, determining the maximum correlation peak as a valid correlation peak.

[0008] According to an embodiment of the present invention, the verifying the validity of the maximum correlation peak includes: determining the sampling point interval associated with the maximum correlation peak; the sampling point interval does not include the sampling point corresponding to the peak value of the maximum correlation peak; determining the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak.

[0009] According to an embodiment of the present invention, the determining the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak includes: based on the autocorrelation results corresponding to each sampling point within the sampling point interval, determining the average autocorrelation result; determining the signal-to-noise ratio of the peak value of the maximum correlation peak to the average autocorrelation result; wherein, the signal-to-noise ratio characterizes the shape of the maximum correlation peak, and the larger the signal-to-noise ratio, the sharper the maximum correlation peak; in the case where the signal-to-noise ratio exceeds the signal-to-noise ratio threshold, determining that the maximum correlation peak is valid.

[0010] According to an embodiment of the present invention, in the case where the autocorrelation result exceeds the dynamic threshold, determining the maximum correlation peak includes: comparing the current autocorrelation result with the dynamic threshold; in the case where the autocorrelation result exceeds the dynamic threshold, updating the dynamic threshold based on the current autocorrelation result to obtain a new dynamic threshold; the new dynamic threshold is used to compare with the newly obtained autocorrelation result next time; continue to receive the signal sequence, and return to the step of comparing the current autocorrelation result with the dynamic threshold to continue execution until the current autocorrelation result does not exceed the dynamic threshold obtained by the most recent update, to obtain the target dynamic threshold; verify the effectiveness of the target dynamic threshold, and in the case where the target dynamic threshold is effective, determine the current autocorrelation result as the maximum correlation peak.

[0011] According to an embodiment of the present invention, verifying the effectiveness of the target dynamic threshold includes: determining a preset number of target sampling points after the current sampling point, and respectively determining the autocorrelation results corresponding to each target sampling point; the current sampling point corresponds to the current autocorrelation result; in the case where the autocorrelation results corresponding to each target sampling point do not exceed the autocorrelation result corresponding to the current sampling point, determine that the target dynamic threshold is effective.

[0012] According to an embodiment of the present invention, after determining the valid correlation peak, before starting signal synchronization in the case where the valid correlation peak and the historical valid correlation peak form a continuous correlation peak, the method further includes: determining the historical valid correlation peak, and determining the first distance between the historical valid correlation peak and the current valid correlation peak; in the case where the first distance meets the distance threshold condition, increase the adjacent count value; in the case where the first distance does not meet the distance threshold condition, reset the adjacent count value; in the case where the adjacent count value exceeds the preset count threshold, determine that the valid correlation peak and the historical valid correlation peak form a continuous correlation peak.

[0013] According to an embodiment of the present invention, in the case of receiving a signal sequence, determining the autocorrelation result based on a known signal sequence includes: performing a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result; determining the target historical cross-correlation result; performing an autocorrelation operation on the cross-correlation result and the target historical cross-correlation result to obtain the autocorrelation result.

[0014] According to an embodiment of the present invention, performing a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result includes: determining the symbol coefficient corresponding to each sampling point based on the signal amplitude corresponding to each sampling point in the signal sequence; wherein, the positive and negative of the signal amplitude are the same as the positive and negative of the symbol coefficient; determining the symbol sequence corresponding to the signal sequence based on the symbol coefficient corresponding to each sampling point; performing a cross-correlation operation on the symbol sequence and the known signal sequence to obtain the cross-correlation result.

[0015] According to an embodiment of the present invention, performing a cross-correlation operation on the symbol sequence and the known signal sequence to obtain a cross-correlation result includes: for any sampling point, multiplying the symbol coefficient corresponding to the targeted sampling point by the known signal at the same position in the known signal sequence to obtain a cross-correlation value corresponding to the targeted sampling point; and obtaining the cross-correlation result based on the sum of the cross-correlation values corresponding to each sampling point in the signal sequence.

[0016] According to an embodiment of the present invention, performing an autocorrelation operation on the cross-correlation result and the target historical cross-correlation result to obtain an autocorrelation result includes: multiplying the cross-correlation result by the target historical cross-correlation result to obtain an autocorrelation value; and obtaining the autocorrelation result based on the absolute value of the autocorrelation value.

[0017] According to an embodiment of the present invention, there is a second spacing between the target historical cross-correlation result and the cross-correlation result, and the length of the second spacing is the same as the length of the known signal sequence.

[0018] According to an embodiment of the present invention, the steps of signal synchronization include: receiving a frame preamble signal; the frame preamble signal includes a synchronization sequence and a flag sequence; whenever an effective correlation peak is determined based on the received synchronization sequence, performing a signal transformation process on the received synchronization sequence to obtain a signal transformation result; the signal transformation result is used for channel estimation; and ending signal synchronization when it is determined that the flag sequence is received.

[0019] According to an embodiment of the present invention, the method further includes: when it is determined, based on the autocorrelation result corresponding to any effective correlation peak, that the autocorrelation value is negative, determining that the flag sequence is received; wherein the boundary position between the synchronization sequence and the flag sequence is the end position of signal synchronization.

[0020] According to an embodiment of the present invention, the sequence length of the signal sequence is the same as the sequence length of the known signal sequence, and the known signal sequence corresponds to the synchronization sequence.

[0021] In a second aspect, the present invention provides a power line carrier signal synchronization device, and the device includes: An operation module, configured to determine an autocorrelation result based on a known signal sequence when a signal sequence is received; A processing module, configured to determine an effective correlation peak when the autocorrelation result exceeds a dynamic threshold; the dynamic threshold is dynamically updated according to the change trend of multiple autocorrelation results; A synchronization module, configured to start signal synchronization when the effective correlation peak and a historical effective correlation peak form a continuous correlation peak.

[0022] According to the power line carrier signal synchronization device provided by the present invention, by detecting a signal sequence and, in the case of receiving the signal sequence, determining an autocorrelation result based on a known signal sequence, the synchronization feature in the signal can be effectively detected through autocorrelation processing, improving the accuracy and reliability of synchronization detection; in the case where the autocorrelation result exceeds a dynamic threshold, a valid correlation peak is determined, which can eliminate invalid correlation peaks, improving the anti-interference ability of synchronization detection, and adopting a dynamic threshold mechanism based on the change trend of the autocorrelation result can adaptively update the threshold, making the identification of valid correlation peaks more accurate; and in the case where the valid correlation peak and the historical valid correlation peak form a continuous correlation peak, by detecting the continuous correlation peaks, the stability and consistency of the synchronization signal are ensured, thereby reliably starting the signal synchronization process, reducing the possibility of misjudgment and missed judgment, achieving efficient and accurate synchronization of signals in a complex channel environment, and enhancing the robustness and reliability of signal synchronization.

[0023] In a third aspect, the present invention provides a signal synchronization system, which includes: A signal sending device for sending a carrier signal; the carrier signal includes a frame preamble signal, a frame control signal, and a data payload; A signal receiving device for executing and implementing the power line carrier signal synchronization method as described in the first aspect, so as to extract the data payload carried in the carrier signal based on the frame control signal after the signal synchronization ends.

[0024] In a fourth aspect, the present invention provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the power line carrier signal synchronization method as described in the first aspect above.

[0025] In a fifth aspect, the present invention provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the power line carrier signal synchronization method as described in the first aspect above.

[0026] In a sixth aspect, the present invention provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the power line carrier signal synchronization method as described in the first aspect above.

[0027] In a seventh aspect, the present invention provides a computer program product, including a computer program. When the computer program is executed by a processor, it implements the power line carrier signal synchronization method as described in the first aspect above.

[0028] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned by practice of the present invention. Description of the Drawings

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of embodiments in conjunction with the following drawings, in which: Figure 1 is a schematic structural diagram of a PPDU signal frame provided in some embodiments of the present invention; Figure 2 is a schematic structural diagram of a preamble signal provided in some embodiments of the present invention; Figure 3 is a schematic structural diagram of a power line carrier signal synchronization system provided in some embodiments of the present invention; Figure 4 is a schematic flowchart of a power line carrier signal synchronization method provided in some embodiments of the present invention; Figure 5 is a schematic diagram of the principle of a sampling point interval provided in some embodiments of the present invention; Figure 6 is a schematic diagram of the shape of a maximum correlation peak provided in some embodiments of the present invention; Figure 7 is a schematic flowchart of a power line carrier signal synchronization method provided in some other embodiments of the present invention; Figure 8 is a schematic diagram of a cross-correlation result obtained by performing a cross-correlation operation between a signal sequence and a known synchronization sequence under noise-free conditions in some embodiments of the present invention; Figure 9 is a schematic diagram of an autocorrelation result obtained by performing an autocorrelation operation based on the cross-correlation result under noise-free conditions in some embodiments of the present invention; Figure 10 is a schematic diagram of a cross-correlation result obtained by performing a cross-correlation operation between a signal sequence and a known synchronization sequence under noise interference in some embodiments of the present invention; Figure 11 is a schematic diagram of an autocorrelation result obtained by performing an autocorrelation operation based on the cross-correlation result under noise interference in some embodiments of the present invention; Figure 12 is a schematic structural diagram of a power line carrier signal synchronization device provided in some embodiments of the present invention; Figure 13 is a schematic structural diagram of a computer device provided in some embodiments of the present invention. Detailed Embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs; the terms used in the specification of the present application in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention; the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of the present invention or the above drawings are used to distinguish different objects, rather than to describe a specific order or primary-secondary relationship.

[0032] Referring to "embodiments" in the present invention means that specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present invention. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described in the present invention can be combined with other embodiments.

[0033] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "attached" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0034] The term "and / or" in the present invention is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present invention generally represents an "or" relationship between the front and rear associated objects.

[0035] The "multiple" mentioned in the present invention refers to two or more (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0036] With the widespread deployment of carrier communication systems such as power line communication in the fields of smart grid, smart home, and industrial automation, the requirements for the real-time and reliability of data transmission in communication systems are increasing day by day. Orthogonal Frequency Division Multiplexing (OFDM) is a modulation technology widely used in modern communication systems. Its core idea is to decompose a high-speed data stream into multiple parallel low-speed subcarrier signals for transmission. Due to the strict orthogonality of each subcarrier in the frequency domain, OFDM technology not only effectively improves the spectrum utilization rate but also has good anti-multipath interference ability.

[0037] However, to maintain the orthogonality between subcarriers, OFDM systems have extremely high requirements for the accuracy of time synchronization and frequency synchronization. Especially at the receiving end, if the synchronization deviation is large, it will lead to the destruction of the orthogonality between subcarriers, thus causing serious Inter-Symbol Interference (ISI) and Inter-Carrier Interference (ICI), and further seriously affecting the demodulation performance.

[0038] In such systems, signal synchronization, as a key pre-step to ensure the correctness of frame-level reception, has a direct impact on the stability and efficiency of the entire communication process. Especially in low signal-to-noise ratio environments or strong interference scenarios, traditional synchronization algorithms often struggle to balance peak recognition accuracy, synchronization delay, and computational complexity, resulting in missed communication frames or synchronization failures, severely restricting the further improvement of system performance.

[0039] On the other hand, current mainstream synchronization methods mostly focus on the mutation detection of the cross-correlation function at specific positions or rely on fixed thresholds to judge the correlation peaks. This approach is difficult to adapt flexibly to different channel states and is prone to false judgments or missed judgments. To achieve a more robust and adaptive frame synchronization process, there is an urgent need for a signal synchronization mechanism that can dynamically respond to channel changes, improve the reliability of peak determination, and effectively control the synchronization delay.

[0040] In view of this, the present invention proposes a power line carrier signal synchronization method based on a joint determination mechanism of cross-correlation and auto-correlation. By introducing technical means such as symbol processing, dynamic threshold update, and continuous peak verification, this method not only improves the robustness and accuracy of synchronization determination but also reduces the computational complexity to a certain extent, and is particularly suitable for synchronization detection under low signal-to-noise ratios.

[0041] The following will combine the accompanying drawings to elaborate in detail on the power line carrier signal synchronization method and others provided by the embodiments of the present invention through specific embodiments and their application scenarios.

[0042] For the HPLC system, the physical layer, data link layer, application layer protocols of the broadband carrier communication standard and related inspection specifications are detailedly specified in the industry technical specifications. In the technical specifications, OFDM symbols are usually transmitted sequentially through individual PPDU frames (Physical Protocol Data Unit).

[0043] Figure 1 It is a schematic structural diagram of the PPDU signal frame provided in some embodiments of the present invention. As Figure 1 shown, the PPDU frame usually includes a preamble signal, a frame control signal (FC), and a data payload (PL). Among them, the preamble signal is used for frame synchronization and channel estimation. The frame control signal is used to describe the basic information of the frame, such as the modulation method, subcarrier distribution, etc. The data payload is used to describe the actual data part to be transmitted.

[0044] Figure 2 It is a schematic structural diagram of the preamble signal provided in some embodiments of the present invention. Among them, the preamble signal is a periodic sequence known to both the transmitter and the receiver. As Figure 2 shown, SYNCP (Synchronization Pattern) is used to provide a synchronization signal for the receiving end to help the receiving end identify the start of the frame and can be called a synchronization sequence. SYNCM (Synchronization Marker) is used to mark the end of the frame and can be called a marker sequence. The repetition interval (RI) is the gap / interval in the preamble frame to avoid interference or superposition between preamble symbols.

[0045] Generally speaking, the preamble signal includes 10.5 SYCNP sequences and 2.5 SYNCM sequences. Each SYCNP sequence includes 1024 sampling point signals, and each SYNCM sequence includes 1024 sampling point signals.

[0046] During the data transmission process, the data is first organized into a logical frame at the upper layer protocol, the logical frame is encapsulated into a PPDU frame and transmitted to the physical layer. The physical layer performs OFDM modulation on the PPDU frame and sends it as a continuous signal through the power line.

[0047] Figure 3 It is a schematic structural diagram of the power line carrier signal synchronization system provided in some embodiments of the present invention. The power line carrier signal synchronization method provided by the present invention can be applied to such as Figure 3The signal synchronization system shown. The signal synchronization system includes a signal transmitting device and a signal receiving device. The signal transmitting device is used to transmit a carrier signal. Among them, the carrier signal includes a preamble signal, a frame control signal, and a data payload.

[0048] Exemplarily, the signal transmitting device receives data from the data link layer, processes and transforms it through a series of power line carrier signal processes, processes the encoded data using OFDM modulation, modulates the preamble signal, frame control signal, and data payload to form an OFDM signal, also known as a carrier signal, and transmits the carrier signal to the power line.

[0049] After detecting the signal from the power line, the signal receiving device enters the frame synchronization state, accurately locates the frame synchronization position for subsequent data frame extraction, such as extracting the frequency domain features required for channel estimation; when the SYNCM sequence, i.e., the flag sequence, appears, the final positioning of frame synchronization is completed, and the starting position of the frame control signal is determined to complete signal synchronization. After signal synchronization is completed, the signal receiving device extracts the data payload carried in the carrier signal based on the frame control signal, and restores it to decoded data information through decoding and demodulation processing, and finally sends it to the data link layer for subsequent protocol parsing.

[0050] Among them, the signal transmitting device and the signal receiving device can be, for example, computer devices. The computer device can be a power line communication terminal, a concentrator device, a smart meter, a communication module embedded device, or a communication test terminal, etc. Or, the computer device can also be a device with computing capabilities or an intelligent robot for performing steps such as signal acquisition, processing, and synchronization in the present invention.

[0051] During the process of signal synchronization, the present invention performs cross-correlation processing based on a locally known sequence and the received signal sequence, and at the same time introduces an autocorrelation mechanism to identify potential correlation peak positions. During the detection process, the accurate positioning of the correlation peak is achieved by continuously tracking the maximum value of the absolute value of the autocorrelation, effectively eliminating false correlation peaks, and starting signal synchronization by detecting multiple consecutive valid correlation peaks, further enhancing the robustness of signal synchronization.

[0052] The power line carrier signal synchronization method provided by the present invention can adaptively process complex channel characteristics such as burst noise and periodic interference existing in the power line, and is applicable to, for example, smart grid communication, industrial automation, home broadband power line networks, and other wireless or wired communication systems based on OFDM modulation, with broad practicality and promotion value.

[0053] The power line carrier signal synchronization method provided by the present invention, the execution subject of this method can be a signal receiving device, or a functional module or functional entity in the signal receiving device that can implement this method.

[0054] Taking the signal receiving device as an example of the execution entity, the power line carrier signal synchronization method provided by the present invention will be described below.

[0055] Figure 4 It is a schematic flowchart of the power line carrier signal synchronization method provided by the present invention in some embodiments. As Figure 4 shown, the power line carrier signal synchronization method includes: step 420, step 440, and step 460.

[0056] Step 420: When a signal sequence is received, determine the autocorrelation result based on the known signal sequence.

[0057] Among them, the signal sequence is formed by arranging sampling point signals of a certain length in chronological order. A sampling point refers to the signal value obtained at a certain sampling period when sampling a continuous signal. Among them, the sampling period can be determined according to the actual situation.

[0058] The signal receiving device can usually sample the continuous signal at uniform time intervals to obtain discrete sampling points, and a set of preset numbers of discrete sampling points forms a signal sequence. Exemplarily, the length of the signal sequence is 1024 sampling points.

[0059] Alternatively, the signal receiving device can set a sliding window of a certain length, and the signal within the sliding window is the current signal sequence. The length of the sliding window can be 1024, corresponding to 1024 sampling point signals.

[0060] For the received signal sequence, the signal receiving device performs correlation evaluation based on the known signal sequence to obtain the autocorrelation value. Among them, the autocorrelation value has positive and negative signs, and the absolute value of the autocorrelation value is called the autocorrelation result. Among them, the known signal sequence refers to a signal sequence that has been determined in advance. In the embodiments of the present invention, the known signal sequence can be a locally stored synchronization sequence, that is, a local SYNCP sequence.

[0061] For example, the signal receiving device slides and matches in the received signal sequence, calculates the cross-correlation result between each sampling point signal in the signal sequence and the known signal sequence to characterize the correlation between the two. Each sampling point position corresponds to a cross-correlation result, and the entire cross-correlation process outputs a set of continuous cross-correlation sequences.

[0062] Among them, in order to improve the accuracy and computational efficiency of cross-correlation matching, it is usually required that the input signal sequence for matching be the same in length as the local synchronization sequence. For this purpose, the sequence length of the signal sequence is the same as that of the known signal sequence, and the known signal sequence corresponds to the synchronization sequence, so as to retain the correlation characteristics of the signal to the greatest extent, avoid recognition errors caused by data truncation or alignment deviation, and at the same time reduce the consumption of unnecessary computing resources. Exemplarily, the lengths of the signal sequence and the local SYNCP sequence are both 1024.

[0063] In one way, since autocorrelation is the cross-correlation of a signal with itself, the autocorrelation result can be obtained by calculating the cross-correlation of the signal with itself. Cross-correlation is used to measure the degree of correlation between the received signal sequence and the known signal sequence, and it can usually be determined by calculating the sum of products of the received signal sequence and the known signal sequence. Therefore, the signal receiving device can first perform a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result; whenever a cross-correlation result is calculated, the signal receiving device stores it, so that subsequently, the autocorrelation operation can be performed on the cross-correlation result and the cross-correlation results calculated historically to obtain the autocorrelation result.

[0064] In another way, the signal receiving device can establish a neural network or machine learning model related to the signal sequence through the mapping relationship between the historical signal sequence and the known signal sequence, and after training is completed, use the current signal sequence as the input to obtain the autocorrelation result output by the neural network or machine learning model.

[0065] In yet another way, the signal receiving device can also extract the part containing the known signal sequence from the received signal sequence and perform an autocorrelation operation on this part, such as calculating the sum of products of the signals at each sampling point and the signals at the sampling points after a certain time delay, to obtain the autocorrelation result.

[0066] Step 440: When the autocorrelation result exceeds the dynamic threshold, determine the valid correlation peak; the dynamic threshold is dynamically updated according to the change trend of multiple autocorrelation results.

[0067] When there is a large correlation between the signal sequence and the known signal sequence, combining the historical autocorrelation results of each sampling point, a spike shape will appear in the data distribution, that is, the autocorrelation peak, simply referred to as the correlation peak.

[0068] Among them, the correlation peak refers to the peak value that appears in the autocorrelation process, indicating that two signals or the signal itself have the maximum correlation at a specific time delay. For example, in the above first way, the correlation peak means that the cross-correlation result of a certain sampling point has the maximum correlation with the cross-correlation result of another sampling point calculated historically.

[0069] In the case where the autocorrelation result exceeds the dynamic threshold, it indicates that the current autocorrelation result is very likely to be at the peak position. At this time, the signal receiving device can determine the maximum correlation peak based on the current autocorrelation result. Among them, in the process of finding the maximum correlation peak each time, the dynamic threshold starts from the initial dynamic threshold and is continuously updated dynamically with the changing trend of multiple autocorrelation results that are continuously determined until the dynamic threshold reaches the maximum value, which means that the autocorrelation result also reaches a maximum value. At this time, the current autocorrelation result is very likely to be a maximum correlation peak.

[0070] Since there may be pulse signals or burst noises in power line communication, etc., this may cause correlation peaks to appear even if the signal sequence is not correlated with the known signal sequence. Therefore, in order to screen out the true correlation peaks, the detected maximum correlation peaks need to be further verified for effectiveness to obtain effective correlation peaks. For example, the signal receiving device can judge based on the autocorrelation results of other sampling points in the area near the current sampling point to determine whether the current sampling point is the true maximum correlation peak. In the case where it is determined that the current sampling point is the true maximum correlation peak, the signal receiving device determines an effective correlation peak. After that, the signal receiving device can judge the next effective correlation peak.

[0071] In actual power line communication, noise interference will affect the judgment of the maximum correlation peak. For this reason, in the embodiments of the present invention, by setting an initial dynamic threshold, in the process of finding the maximum correlation peak each time, this initial dynamic threshold will be dynamically adjusted and updated with the changing trend of the autocorrelation results of each sampling point to adaptively detect the maximum correlation peak within a certain sampling point interval. Among them, the changing trend of the autocorrelation result represents the pattern or direction of the autocorrelation result changing with time or the sampling signal, such as continuous increase, continuous decrease or oscillation, etc.

[0072] In some embodiments, the signal receiving device repeats the process of finding the maximum correlation peak during the entire frame synchronization process; during the process of receiving the signal sequence, repeats the process of finding the maximum correlation peak; in any process of finding the maximum correlation peak, compares the autocorrelation result of the current sampling point with the dynamic threshold and updates the dynamic threshold based on the comparison result until the maximum correlation peak in the current search process is determined; among them, the dynamic threshold at the start of each search process is the initial value; after determining the maximum correlation peak in any case, continue to receive the subsequent signal sequence and restart the above process of finding the maximum correlation peak until frame synchronization is completed and signal synchronization is entered. The process of finding the maximum correlation peak and receiving the signal sequence can be synchronized or asynchronous.

[0073] In other words, during the process of continuously receiving a signal sequence, the signal receiving device will have to search for the maximum correlation peak multiple times. For example, when receiving the sampled point signal, the signal receiving device determines whether it is the maximum correlation peak. If not, it continues to search backward until the first maximum correlation peak is found, and then starts to search for the next maximum correlation peak... until the frame synchronization position is found and signal synchronization is enabled.

[0074] Among them, at the beginning of the judgment process of each maximum correlation peak, the signal receiving device starts the comparison and update with the same initial dynamic threshold. The dynamic thresholds finally determined during the judgment processes of each maximum correlation peak can be the same or different to adapt to the channel characteristics or noise changes.

[0075] For example, at each sampled point, the signal receiving device calculates the corresponding autocorrelation result and compares it with the currently set dynamic threshold. If the autocorrelation result exceeds the dynamic threshold, the threshold is updated, and the autocorrelation results of subsequent sampled points are continuously compared. When it is detected that a certain sampled point meets the maximum correlation peak determination condition (for example, the autocorrelation values of several subsequent sampled points do not exceed its current value), this point is confirmed as the maximum correlation peak in a search process. At this time, the signal receiving device records the position of the sampled point corresponding to this maximum correlation peak, and then continues to receive the signal and repeats the above search process. In the new search process for the maximum correlation peak, the initial threshold is also used as the starting point to re-perform autocorrelation comparison, threshold update, and maximum peak determination until it is detected that the frame synchronization condition is met.

[0076] Thus, by introducing the dynamic threshold adjustment and maximum correlation peak detection mechanism in the local area, the robustness and self - adaptability of the correlation peak determination in signal synchronization are enhanced, the influence of noise interference on signal synchronization is reduced, and the accuracy and robustness of signal synchronization detection can be improved.

[0077] Step 460: When the valid correlation peak and the historical valid correlation peak form a continuous correlation peak, start signal synchronization.

[0078] Among them, the historical valid correlation peak refers to the valid correlation peak detected in the previous signal processing. The continuous correlation peak refers to the correlation peaks that appear continuously at the expected interval, and the continuous correlation peak can be used to indicate the periodic signal. For the sake of distinction, the interval between the historical valid correlation peak and the current valid correlation peak is called the first interval. If the two valid correlation peaks are not continuous, such as the first interval between them exceeds the interval threshold or there are invalid correlation peaks in the middle, etc., there may be a situation where one or more signal sequences are missed during the signal synchronization process. If signal synchronization is directly performed, it will lead to inaccurate signal reception.

[0079] Therefore, in the embodiments of the present invention, the signal receiving device further detects continuous correlation peaks. By using the judgment strategy of continuous correlation peaks, the robustness of the synchronization process is further enhanced, and the possibilities of false judgment and missed judgment are reduced, which is particularly applicable to complex and changeable communication environments.

[0080] Specifically, for any current valid correlation peak, the signal receiving device jointly judges it with historical valid correlation peaks to determine whether it forms a continuous correlation peak with the historical valid correlation peaks. For example, when the historical valid correlation peak P t-2 , the historical valid correlation peak P t-1 and the current valid correlation peak P t are continuous, and the spacing between any two valid correlation peaks does not exceed the spacing threshold, then the signal receiving device determines that the valid correlation peak P t forms a continuous correlation peak with the historical valid correlation peaks P t-1 and P t-2 . There can be multiple historical valid correlation peaks. Generally speaking, the more the number, the stricter the determination conditions for continuous correlation peaks.

[0081] In the case of detecting continuous correlation peaks, it usually means that there is a repetitive pattern in the received signal that is highly similar to the local known signal sequence, corresponding to the periodic occurrence of the synchronization sequence SYNCP in the frame preamble signal. In other words, the received signal has a high correlation with the local known signal sequence at multiple positions, which means that it is very likely to have successfully located the starting position of the frame preamble signal.

[0082] Furthermore, when the valid correlation peak forms a continuous correlation peak with the historical valid correlation peaks, the signal receiving device can initiate signal synchronization and continue to search for valid correlation peaks backward. When a negative valid correlation peak is obtained, it indicates that the flag sequence SYNCM is detected, indicating that frame synchronization is completed. The signal receiving device takes the position at the junction of the synchronization sequence SYNCP and the flag sequence SYNCM as the final positioning position of frame synchronization to complete frame synchronization.

[0083] After frame synchronization is completed, the signal receiving device can extract the data payload carried in the carrier signal based on the frame control signal. For example, the signal receiving device locates and analyzes the frame control signal to extract important information about the frame structure and content, such as frame type, length, modulation method, and coding scheme, etc. Thus, based on the information provided in the frame control signal, the signal receiving device can demodulate the received signal according to the modulation method indicated by the frame control signal to recover the baseband signal. Or, the signal receiving device can also decode the demodulated signal according to the coding scheme indicated by the frame control signal to correct possible errors during transmission and recover the original data payload.

[0084] According to the power line carrier signal synchronization method provided by the present invention, by detecting the signal sequence and, when the signal sequence is received, determining the autocorrelation result based on the known signal sequence, the synchronization feature in the signal can be effectively detected through autocorrelation processing, improving the accuracy and reliability of synchronization detection; when the autocorrelation result exceeds the dynamic threshold, an effective correlation peak is determined, which can eliminate invalid correlation peaks, improving the anti-interference ability of synchronization detection, and adopting a dynamic threshold mechanism based on the change trend of the autocorrelation result can adaptively update the threshold, making the identification of effective correlation peaks more accurate; and when the effective correlation peak and the historical effective correlation peak form a continuous correlation peak, by detecting the continuous correlation peaks, the stability and consistency of the synchronization signal are ensured, thereby reliably starting the signal synchronization process, reducing the possibility of misjudgment and missed judgment, achieving efficient and accurate synchronization of the signal in a complex channel environment, and enhancing the robustness and reliability of signal synchronization.

[0085] Before performing signal synchronization judgment, the signal receiving device should have the ability to monitor the channel state in real time and be able to judge whether there is a signal sequence to be received based on this, thereby triggering the subsequent synchronization detection process. For this purpose, in some embodiments, before step 420, the power line carrier signal synchronization method provided by the present invention further includes step 410: monitoring the power line channel and determining whether a signal sequence is detected.

[0086] In this embodiment, the signal receiving device can continuously monitor the signal amplitude or power level in the power line channel and compare it with a preset noise threshold. When the signal strength exceeds the background noise threshold and lasts for a certain time or meets specific characteristics, it is considered that a possible signal sequence is detected, and then the subsequent cross-correlation and autocorrelation processing stages are entered.

[0087] Among them, the specific characteristics include but are not limited to rising edges, power mutations, or spectral characteristics, etc.

[0088] Exemplarily, the signal receiving device samples the power line voltage signal at regular time intervals and accumulates the signal energy values of a sampling window (such as 1024 points). If the energy value exceeds the noise threshold for 3 consecutive windows, it is determined that a signal sequence is detected, and steps 420 to 460 are started to perform the subsequent signal synchronization process.

[0089] In the above embodiment, by predicting whether a signal is received, it is avoided to wrongly enter the synchronization process in the signal-free state, improving the system efficiency and saving system power consumption. At the same time, it can effectively distinguish the communication signal in the power line from environmental noise or instantaneous interference, reducing the possibility of false triggering of frame synchronization.

[0090] In HPLC, signal synchronization is a key technology to ensure accurate data transmission and reception. In related technologies, synchronization is performed through cross-correlation, which performs poorly in a power line communication environment with strong noise interference such as narrowband interference, background noise, and low signal-to-noise ratio, and it is difficult to meet the requirements of high-reliability communication. Therefore, the present invention proposes a method for calculating the autocorrelation result by combining cross-correlation and autocorrelation operations to improve the accuracy and robustness of signal synchronization.

[0091] For this purpose, in some embodiments, in step 420, when a signal sequence is received, the autocorrelation result is determined based on a known signal sequence, including steps 422 to 426: Step 422: Perform a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result; Step 424: Determine the target historical cross-correlation result; Step 426: Perform an autocorrelation operation on the cross-correlation result and the target historical cross-correlation result to obtain an autocorrelation result.

[0092] In this embodiment, the signal receiving device performs a cross-correlation operation on the received signal sequence and the local known signal sequence to calculate the cross-correlation result of each sampling point in the signal sequence. The known signal sequence is, for example, the known synchronization sequence SYNCP. Among them, the cross-correlation result can be, for example, the sum of the products of the signal values of each sampling point signal in the signal sequence and the signal values of each sampling point signal in the known signal sequence.

[0093] For example, the signal receiving device slides and matches in the received signal sequence to calculate the cross-correlation result between each sampling point signal in the signal sequence and the known signal sequence to characterize the correlation between the two. Each sampling point position corresponds to a cross-correlation result, and the entire cross-correlation process outputs a set of continuous cross-correlation sequences.

[0094] Whenever the cross-correlation result of a sampling point is calculated, the signal receiving device saves it. For example, the signal receiving device can maintain a buffer in the memory to store the cross-correlation results of multiple sampling points for a period of time for subsequent analysis.

[0095] For the cross-correlation result of the current sampling point, the signal receiving device extracts the target historical cross-correlation result from the historical cross-correlation results, and performs an autocorrelation operation on the current cross-correlation result and the target historical cross-correlation result to calculate the autocorrelation value and obtain the autocorrelation result of the current sampling point. Among them, the autocorrelation result can be, for example, the product of the cross-correlation result of the current sampling point and the target historical cross-correlation result (the cross-correlation result corresponding to the target historical sampling point).

[0096] In the above embodiments, by combining cross-correlation and autocorrelation operations, and performing autocorrelation operations on the current cross-correlation result and historical data, the correlation peak can be more significantly highlighted, so as to more accurately identify repeated synchronization patterns, thereby improving the accuracy and reliability of synchronization detection.

[0097] In communication systems based on orthogonal frequency division multiplexing technology such as high-speed power line communication, in order to effectively decode the received signal, frame synchronization needs to be accurately completed at the receiving end. Cross-correlation is a commonly used synchronization detection method. By calculating the similarity between the received signal sequence and the locally pre-stored known signal sequence, the starting position of the synchronization sequence in the received signal can be located. However, in the power line communication scenario, due to the influence of interference factors such as burst pulse noise, narrowband interference, and background noise, the traditional cross-correlation method relying on amplitude may not be applicable to the actual application environment with limited hardware resources or poor channel conditions due to problems such as complex multiplication calculations and sensitivity to amplitude fluctuations.

[0098] In addition, the efficiency of signal synchronization is also one of the keys in high-speed power line carrier communication. The usual cross-correlation operation is to perform a multiplication operation on the received signal sequence and the locally known signal sequence, which not only consumes high computing resources but also has relatively low computing efficiency.

[0099] In view of this, in some embodiments, in step 422, performing a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result includes steps 4222 to 4226: Step 4222, based on the signal amplitudes corresponding to each sampling point in the signal sequence, determining the symbol coefficients corresponding to each sampling point; wherein, the positive and negative of the signal amplitude are consistent with the positive and negative of the symbol coefficient; Step 4224, based on the symbol coefficients corresponding to each sampling point, determining the symbol sequence corresponding to the signal sequence; Step 4226, performing a cross-correlation operation on the symbol sequence and the known signal sequence to obtain a cross-correlation result.

[0100] In this embodiment, for the received signal sequence, the signal receiving device determines the symbol coefficient corresponding to each sampling point according to the signal amplitude corresponding to each sampling point in the signal sequence.

[0101] Among them, the positive and negative of the symbol coefficient are consistent with the positive and negative of the signal amplitude. In other words, each symbol coefficient represents the positive and negative polarity of the signal amplitude at that sampling point, +1 represents a positive value, -1 represents a negative value, and 0 represents 0 or approximately 0.

[0102] For example, a signal receiving device receives a signal sequence of length 1024, including 1024 sampling points. Then, based on the signal amplitude corresponding to the sampling point signal, if the amplitude is positive, the symbol coefficient is taken as +1; if the amplitude is negative, the symbol coefficient is taken as -1. In this way, the symbol coefficients corresponding to each sampling point can be obtained quickly. The symbol coefficients corresponding to each sampling point constitute a symbol sequence corresponding to the signal sequence, such as {+1, +1, -1, ……, +1, -1}, etc.

[0103] Furthermore, the signal receiving device can then perform a cross-correlation operation based on the symbol sequence and a known signal sequence. Since only the symbol coefficients corresponding to each sampling point are taken, during the cross-correlation operation, the multiplication operation between the symbol sequence corresponding to the signal sequence and the known signal sequence is converted into a simple addition and subtraction operation, greatly reducing the amount of computation.

[0104] In the above embodiment, by simplifying the received signal amplitude to its corresponding symbol coefficient and only retaining the positive and negative polarities, compared with the multiplication operation on the specific amplitude in the traditional cross-correlation operation, the computational complexity and the dependence on the amplitude accuracy are effectively reduced, the processing efficiency is improved, and the stability and real-time performance of synchronous recognition are enhanced.

[0105] Among them, in some embodiments, in step 4226, a cross-correlation operation is performed on the symbol sequence and the known signal sequence to obtain a cross-correlation result, including: for any sampling point, multiplying the symbol coefficient corresponding to the sampling point targeted by the known signal at the same position in the known signal sequence to obtain a cross-correlation value corresponding to the sampling point targeted; based on the sum of the cross-correlation values corresponding to each sampling point in the signal sequence, the cross-correlation result is obtained.

[0106] In this embodiment, for any sampling point in the received symbol sequence, the signal receiving device extracts its corresponding symbol coefficient, such as +1, -1, or 0, etc. The signal receiving device multiplies this symbol coefficient by the symbol at the same position in the known signal sequence to obtain the cross-correlation value corresponding to the current sampling point.

[0107] After that, the signal receiving device sums up the cross-correlation values of each sampling point in the entire signal sequence, and the obtained sum value is the cross-correlation result between the current signal sequence and the known sequence.

[0108] Taking a sliding window of 1024 points in length as an example: First, extract 1024 sampling points covered by the current sliding window from the received signal sequence; for the amplitudes of these 1024 sampling points, calculate their sign coefficients one by one to form a sign sequence of length 1024; then, multiply this sign sequence with the SYNCP sequence stored locally point by point to calculate the product at each pair of positions; sum up these 1024 product values to obtain a cross-correlation result value, which is used as the cross-correlation index corresponding to the current sliding window position; repeat the above process to update the cross-correlation result sequence when the sliding window moves.

[0109] In the above embodiment, by converting the signal amplitude into a sign coefficient, the floating-point multiplication calculation is avoided, greatly reducing the amount of computation and improving the processing efficiency. Even in a low signal-to-noise ratio environment, the relevant peak can be effectively identified, improving the synchronization robustness; in addition, since only the positive and negative sign coefficients of the signal are taken, the hardware implementation difficulty and processing delay are also greatly reduced, making it suitable for deployment on communication terminals or embedded platforms with limited resources.

[0110] In the traditional scheme, the autocorrelation operation often depends on the original received signal itself, with a large amount of computation and being easily interfered by channel disturbances and noise. For this reason, the present invention proposes an autocorrelation calculation method based on the cross-correlation result and its historical value. By using the product of the current cross-correlation value and the historical cross-correlation value to form an autocorrelation value, and then taking its absolute value as the autocorrelation intensity, an index for discriminating the significance of the relevant peak is constructed, which not only reduces the amount of computation but also improves the detection accuracy.

[0111] For this reason, in some embodiments, in step 426, an autocorrelation operation is performed on the cross-correlation result and the target historical cross-correlation result to obtain an autocorrelation result, including: multiplying the cross-correlation result with the target historical cross-correlation result to obtain an autocorrelation value; obtaining the autocorrelation result based on the absolute value of the autocorrelation value.

[0112] To ensure that the current cross-correlation result and the historical data reflect the matching results of the same round or the same structure of the synchronization sequence, in some embodiments, there is a preset distance, called the second distance, between the target historical cross-correlation result and the cross-correlation result, and the length of the second distance is the same as the length of the known signal sequence.

[0113] Thus, it can be ensured that the two reflect two adjacent or repeatedly occurring synchronization sequence matching points (for example, ensuring that the two cross-correlation values respectively reflect the SYNCP segments in two adjacent periods of the received signal), thereby improving the representativeness and stability of the autocorrelation result and reducing the false detection rate.

[0114] In some embodiments, the current cross-correlation result is calculated by computing the symbol sequence corresponding to the currently received signal sequence and a locally known signal sequence (such as the SYNCP sequence) under a certain sliding window. The target historical cross-correlation result can be the cross-correlation result calculated at several positions forward of this sliding window (such as 1024 points ahead).

[0115] The signal receiving device multiplies the current cross-correlation result by the target historical cross-correlation result to obtain the autocorrelation value at the corresponding position. The signal receiving device takes the absolute value of the autocorrelation value as the autocorrelation intensity index at this position, which is used to determine whether there is a significant peak matching the known signal sequence.

[0116] It is easy to understand that the above process can be repeatedly executed under the sliding window mechanism, enabling the system to monitor the repeatability of the cross-correlation results in real time, thereby identifying potential synchronization points, continuously updating the autocorrelation results, being applicable to dynamic detection, and improving the response efficiency and accuracy of the synchronization process.

[0117] Exemplarily, at the i-th sliding window position, the signal receiving device calculates the cross-correlation value as Corr_i. And the signal receiving device records the historical cross-correlation result Corr_i-1024 at the (i−1024)-th sliding window position. Then the signal receiving device multiplies Corr_i and Corr_i-1024 to obtain the autocorrelation value AutoCorrVal = Corr_i × Corr_i-1024. Further, the signal receiving device takes the absolute value of this value to obtain the autocorrelation result AbsAutoCorr = |AutoCorr|.

[0118] In the above embodiments, by performing autocorrelation on the current cross-correlation result and the historical cross-correlation result, it can be determined whether the synchronization sequence continuously appears in multiple cycles, and the correlation peak can be identified more quickly and accurately; moreover, using the absolute value of the autocorrelation value as the autocorrelation intensity index can effectively filter out the errors caused by the change of symbol polarity, improving the recognition accuracy in a strong interference environment.

[0119] In the process of implementing signal synchronization based on the cross-correlation and autocorrelation mechanisms, the determination of valid correlation peaks is crucial for synchronization accuracy. Traditional cross-correlation detection often only relies on whether a single peak exceeds a fixed threshold to determine the correlation. However, in a complex channel environment with strong interference and low signal-to-noise ratio such as power line communication, noise is extremely likely to induce false peaks, resulting in synchronization misjudgment.

[0120] Therefore, in some embodiments, in step 440, when the autocorrelation result exceeds the dynamic threshold, determining a valid correlation peak includes steps 442 to 444: Step 442: When the autocorrelation result exceeds the dynamic threshold, determine the maximum correlation peak; the peak value of the maximum correlation peak is the current autocorrelation result, and the peak position is the signal position of the sampling point corresponding to the peak. Step 444: Verify the validity of the maximum correlation peak, and when the validity verification passes, determine the maximum correlation peak as the valid correlation peak.

[0121] As described above, during the process of continuously receiving signal sequences, the signal receiving device will go through multiple processes of finding the maximum correlation peak. For example, when receiving the sampling point signal, the signal receiving device determines whether it is the maximum correlation peak. If not, it continues to search backward until a maximum correlation peak is found. In this embodiment, an example of any process of finding the maximum correlation peak is used for illustration. The signal receiving device compares the current autocorrelation result with the dynamic threshold to find the point with the maximum peak value of the autocorrelation results within a certain area, takes the peak amplitude and the corresponding position of this point as the current maximum correlation peak, and updates the dynamic threshold with the current autocorrelation result. For the next sampling point, the signal receiving device will compare the autocorrelation result of the next sampling point with the dynamically threshold updated last time, and when the autocorrelation result of the next sampling point exceeds the dynamically threshold updated last time, continue to update the dynamically threshold updated last time for the next comparison... Thus, by continuously updating the dynamic threshold, the most prominent one can be selected from multiple possible correlation peaks, enhancing the stability of synchronization judgment.

[0122] For example, the signal receiving device traverses the autocorrelation values of all sampling points in the current sliding window. Based on the autocorrelation value being greater than the current dynamic threshold, continuously record the maximum value of the peak and its corresponding position. Whenever a higher autocorrelation value appears, the signal receiving device updates the current maximum value and the peak position until the traversal is completed or the autocorrelation value no longer rises, then the maximum correlation peak within the current segment can be determined.

[0123] Subsequently, the signal receiving device verifies the validity of the maximum correlation peak through the set peak validity conditions. Among them, the validity verification can be, for example, but not limited to, verification based on the ratio of the maximum correlation peak to the background noise level, the persistence of the peak, and other optional statistical indicators, etc.

[0124] For example, the signal receiving device selects a predetermined sampling range after the maximum correlation peak as the background reference interval, and calculates the average autocorrelation value within this interval to form a comparison with the maximum correlation peak. If this ratio exceeds the preset threshold, it indicates that the peak is significant and can be determined as a valid correlation peak.

[0125] In the above embodiments, by screening the maximum correlation peak instead of the peak that first exceeds the threshold, it is possible to avoid misidentifying a non-maximum point with large volatility as a valid correlation peak, and it is possible to stably and accurately identify the true synchronization mark under the conditions of complex channel interference and large SNR fluctuations, thereby improving the robustness and accuracy of frame synchronization. In addition, the high-quality identification of valid correlation peaks can help to subsequently judge continuous correlation peaks to smoothly enter the frame synchronization state.

[0126] Among them, verifying the validity of the maximum correlation peak in step 444 includes steps 4442 to 4444: Step 4442, determine the sampling point interval associated with the maximum correlation peak; the sampling point interval does not include the sampling point corresponding to the peak value of the maximum correlation peak; Step 4444, determine the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak.

[0127] In this embodiment, after detecting the maximum correlation peak, the signal receiving device will calculate the signal-to-noise ratio within the sampling point interval around the peak to assist in determining whether the correlation peak has sufficient significance.

[0128] The signal receiving device first determines a sampling point interval corresponding to the maximum correlation peak. This interval is usually a preset length interval (such as 1000 sampling points) after the sampling point where the maximum correlation peak is located. For example, the sampling point interval after shifting backward by a fixed length (such as 20 to 50 sampling points). And this sampling point interval does not include the peak sampling point of the maximum correlation peak to avoid interference from this peak value to the background noise determination.

[0129] The signal receiving device calculates the average value of the autocorrelation results or other statistics within this sampling point interval as a background noise reference. Combining the absolute value of the autocorrelation of the maximum correlation peak, the signal receiving device can calculate the signal-to-noise ratio index between it and this background reference.

[0130] Among them, the signal-to-noise ratio index can be used to measure whether the correlation peak is prominent enough in the background noise, thereby serving as a basis for determining whether it is a valid correlation peak. When this signal-to-noise ratio index exceeds the preset threshold, it is considered that the correlation peak has good significance, and thus it is determined as a valid correlation peak.

[0131] Figure 5 It is a schematic diagram of the principle of the sampling point interval provided by the present invention in some embodiments. Exemplarily, such as Figure 5As shown, starting from the position of the maximum correlation peak, the signal receiving device is shifted backward by 20 sampling points, and the average value of the absolute values of the autocorrelation values corresponding to 1000 sampling points within the sampling point interval is statistically calculated as the noise background. Furthermore, the signal receiving device compares the value of the maximum correlation peak with the background average value. If the ratio exceeds the set threshold, the peak is considered a valid correlation peak; otherwise, it is determined as a false peak or an invalid peak, and the search continues backward for the next potential peak.

[0132] In the above embodiment, by introducing the signal-to-noise ratio index to verify the correlation peak, the probability of misjudging a false correlation peak induced by noise as valid is effectively reduced, and by setting the sampling point interval, different lengths of interference pulses or background noise can be flexibly handled, improving the adaptability to complex power line channel conditions.

[0133] As mentioned above, the power line communication environment is complex, and there are a large number of narrowband interferences, periodic background noises, and random burst noises in the channel, which are likely to cause pseudo-peaks or reduce the peak significance, resulting in synchronization judgment errors. Therefore, further, in step 4444, the signal-to-noise ratio of the maximum correlation peak within the sampling point interval is determined to verify the effectiveness of the maximum correlation peak, including: determining the average autocorrelation result based on the autocorrelation results corresponding to each sampling point within the sampling point interval; determining the signal-to-noise ratio of the peak value of the maximum correlation peak to the average autocorrelation result; and determining that the maximum correlation peak is valid when the signal-to-noise ratio exceeds the signal-to-noise ratio threshold.

[0134] In some embodiments, the signal receiving device selects one or more sampling point intervals adjacent to the maximum correlation peak (such as a fixed-length interval after the peak sampling point), extracts the autocorrelation results within this interval and calculates their average value as the average autocorrelation result.

[0135] Subsequently, the signal receiving device compares the peak value of the maximum correlation peak with the average autocorrelation result to obtain the signal-to-noise ratio index of this peak. Among them, the signal-to-noise ratio characterizes the shape of the maximum correlation peak. The larger the signal-to-noise ratio, the sharper the maximum correlation peak; the smaller the signal-to-noise ratio, the flatter the maximum correlation peak.

[0136] If the calculated signal-to-noise ratio exceeds the signal-to-noise ratio threshold, the signal receiving device determines that the maximum correlation peak is valid; conversely, if the calculated signal-to-noise ratio does not exceed the signal-to-noise ratio threshold, the signal receiving device determines that the maximum correlation peak is invalid.

[0137] Figure 6 is a schematic diagram of the shape of the maximum correlation peak provided by the present invention in some embodiments. Exemplarily, as Figure 6 shown, Figure 6 (a) indicates that the maximum correlation peak is valid, while Figure 6 (b) indicates that the maximum correlation peak is invalid.

[0138] In the above embodiments, by making a judgment based on the signal-to-noise ratio, it is possible to more accurately evaluate whether the relevant peak is prominent, avoid misjudging the noise-induced pseudo-peak as a valid peak, and can suppress low-frequency influences such as burst interference and background clutter, improving the synchronization robustness and accuracy.

[0139] In addition, in traditional solutions, a synchronization strategy of sampling a fixed threshold to judge the relevant peak is usually adopted. However, in an OFDM system, especially in a high-speed power line communication environment, due to the existence of strong background noise, narrowband interference, and bursty impulse noise, the relevant detection results, especially the autocorrelation results, fluctuate greatly, making it difficult for the traditional method to adapt to the severely changing channel conditions and prone to problems such as starting the synchronization process too early or too late.

[0140] To this end, in some embodiments, in step 440, when the autocorrelation result exceeds the dynamic threshold, determining the maximum correlation peak includes: comparing the current autocorrelation result with the dynamic threshold; when the autocorrelation result exceeds the dynamic threshold, updating the dynamic threshold based on the current autocorrelation result to obtain a new dynamic threshold; the new dynamic threshold is used to compare with the newly obtained autocorrelation result next time; continue to receive the signal sequence, and return to the step of comparing the current autocorrelation result with the dynamic threshold and continue to execute until the current autocorrelation result does not exceed the dynamic threshold obtained by the most recent update, to obtain the target dynamic threshold; verify the effectiveness of the target dynamic threshold, and when the target dynamic threshold is effective, determine the current autocorrelation result as the maximum correlation peak.

[0141] In the process of finding the maximum correlation peak each time, the signal receiving device first determines the autocorrelation result k1 of the current sampling point a1 and compares it with the initial dynamic threshold λ0. The initial dynamic threshold can be determined based on the actual power line carrier communication channel.

[0142] If the current autocorrelation result k1 exceeds the initial dynamic threshold λ0, the signal receiving device records the current autocorrelation result k1 and updates λ1 with the current autocorrelation result k1 to obtain a new dynamic threshold λ1. The method of updating the dynamic threshold based on the autocorrelation result includes: using the autocorrelation value of the current autocorrelation result as the value of the new dynamic threshold.

[0143] At this time, the signal receiving device still cannot determine whether the current autocorrelation result is the maximum correlation peak. Therefore, the signal receiving device determines the autocorrelation result k2 of the next sampling point a2, and compares the autocorrelation result k2 of the next sampling point a2 with the dynamic threshold λ1 obtained from the previous update. If the current autocorrelation result k2 exceeds the dynamic threshold λ1 obtained from the previous update, the signal receiving device records the current autocorrelation result k2, and updates the initial dynamic threshold λ1 with the current autocorrelation result k2 to obtain a new dynamic threshold λ2... and continuously repeats the steps of comparison and update.

[0144] If the autocorrelation result kn of a certain sampling point an does not exceed the dynamic threshold λn-1 obtained from the previous update, it indicates that the current autocorrelation result kn is very likely to be a maximum correlation peak. Then the signal receiving device uses the dynamic threshold λn-1 obtained from the previous update as the target dynamic threshold in the process of searching for the maximum correlation peak this time, and verifies the effectiveness of the target dynamic threshold.

[0145] Due to the complex and changeable channel environment, if the autocorrelation value of a certain sampling point is relatively high, but the autocorrelation results of the sampling points immediately adjacent to it continue to rise or fluctuate, it indicates that this point is not a peak, but only an intermediate point in the local rising process. At this time, the updated dynamic threshold may still be updated later. Therefore, verifying the effectiveness of the target dynamic threshold, judging whether the autocorrelation results of the sampling points within a certain range subsequently rise compared with the current autocorrelation result, and then judging whether the current autocorrelation result is the maximum correlation peak in the process of searching for the maximum correlation peak this time can well avoid misjudging interference spikes as the maximum correlation peak.

[0146] When the target dynamic threshold is effective, the signal receiving device determines the current autocorrelation result as the maximum correlation peak. Thus, instead of relying on single-point judgment, it is based on the statistical judgment of a continuous segment of sampling points, effectively suppressing the false triggering phenomenon caused by sudden noise or channel anomalies, and improving the robustness of the system.

[0147] Among them, the method of updating the initial dynamic threshold based on the autocorrelation result includes, for example: updating the initial dynamic threshold to the absolute value of the autocorrelation value.

[0148] In the above embodiments, by introducing a dynamic threshold iterative update mechanism, comparing the autocorrelation result with the current dynamic threshold, adaptively adjusting the threshold level, and combining the subsequent nodes where the update stops to determine the maximum correlation peak, it can effectively adapt to the channel characteristics under different signal-to-noise ratio conditions, and avoid the problems of misjudgment or missed judgment caused by fixed thresholds due to environmental changes. At the same time, by introducing a verification mechanism for the target dynamic threshold, the reliability of correlation peak detection is further enhanced, making the identification of synchronization points more accurate, and improving the robustness and stability of the signal synchronization process.

[0149] Accordingly, in some embodiments, determining the validity of the dynamic threshold obtained in the most recent update includes: determining a preset number of target sampling points after the current sampling point, and respectively determining the autocorrelation results corresponding to each target sampling point; the current sampling point corresponds to the current autocorrelation result; in the case where the autocorrelation results corresponding to each target sampling point do not exceed the autocorrelation result corresponding to the current sampling point, it is determined that the candidate dynamic threshold is valid.

[0150] After identifying a candidate maximum correlation peak, that is, the current autocorrelation result, the signal receiving device needs to further verify the validity of the corresponding dynamic threshold. Specifically, the signal receiving device obtains a plurality of sampling points after the current sampling point as target sampling points, and respectively calculates the autocorrelation values of these target sampling points. If the autocorrelation values of all these target sampling points do not exceed the autocorrelation value of the current sampling point, it can be confirmed that the candidate correlation peak has local maximality, and the dynamic threshold is representative, so that it can be used as an effective target dynamic threshold, and then it is determined that the autocorrelation result corresponding to this sampling point is the maximum correlation peak. By this means, the accuracy of determining the maximum correlation peak in the actual power line carrier communication environment can be effectively improved.

[0151] Among them, the preset number can be, for example, 20 to 50 sampling points, etc., and the specific value can be determined based on the actual communication conditions.

[0152] In the above embodiments, by introducing a dynamic threshold verification mechanism for subsequent sampling points, it is confirmed that the sampling point corresponding to the target dynamic threshold is indeed a local maximum correlation peak, effectively suppressing the false peak judgment caused by burst interference or local noise, thereby improving the accuracy of signal synchronization and avoiding the drift of the synchronization position.

[0153] In a complex noise environment or under multipath interference, single correlation peak detection is prone to phenomena such as accidental peaks, false peaks or missing peaks, resulting in synchronization misjudgment. Therefore, a single detected effective correlation peak is not sufficient to confirm the synchronization state based on this.

[0154] For this reason, in some embodiments, between step 440 and step 460, the power line carrier signal synchronization method provided by the present invention further includes step 450: determining historical effective correlation peaks, and determining a first distance between the historical effective correlation peaks and the current effective correlation peak; in the case where the first distance satisfies the distance threshold condition, increasing the adjacent count value; in the case where the first distance does not satisfy the distance threshold condition, resetting the adjacent count value; in the case where the adjacent count value exceeds the preset count threshold, determining that the effective correlation peak and the historical effective correlation peak form continuous correlation peaks.

[0155] In this embodiment, after detecting the current valid correlation peak, the signal receiving device determines whether the spacing threshold condition is met between the current valid correlation peak and the historical valid correlation peak based on the sampling point spacing therebetween, which is referred to as the first spacing.

[0156] The first spacing is generally consistent with the length of a known synchronization sequence (such as SYNCP), and an allowable error range can be preset to form the spacing threshold condition.

[0157] If the first spacing meets the spacing threshold condition, that is, the first spacing does not exceed the spacing threshold, the signal receiving device considers that the current correlation peak is related to the historical correlation peak and may belong to consecutive synchronization flags; otherwise, it is considered that there is loss or interference in between.

[0158] Moreover, the signal receiving device also maintains an adjacent count value to record the number of times that consecutive spacings meet the condition: if the current spacing meets the condition, the adjacent count value is incremented; if the current spacing does not meet the condition, the count value is reset; when the adjacent count value exceeds the set count threshold, it can be determined that multiple consecutive valid correlation peaks have been detected, and the synchronization state can be confirmed to be entered.

[0159] Exemplarily, assume that the length of the local known synchronization sequence SYNCP is 1024 points, and the preset allowable deviation is ±20 points, that is, the spacing threshold range defined by the spacing threshold condition is [1004, 1044]. The signal receiving device detects the valid correlation peak A for the first time and records its peak position as the sampling point P1 = 2048; subsequently, the valid correlation peak B is detected, and the peak position is P2 = 3075, and the spacing between the two is 1027, within the allowable error; the adjacent count value Begincount++ increases from the initial value 1 (Begincount+ when the current valid correlation peak is detected, and the initial value increases from 0 to 1) to 2; if the valid correlation peak C is detected again later, located at the sampling point P3 = 4099, and the spacing from B is 1024, and the condition is met again, the adjacent count value is incremented to 3, reaching the preset count threshold (such as 3 times), then the signal receiving device determines that A, B, and C are consecutive correlation peaks, and the signal receiving device enters the frame synchronization state, that is, the SYNCBegin state. If the spacing is 980 or 1060 at a certain time and does not meet the range [1004, 1044], the adjacent count value is cleared to avoid misjudgment.

[0160] In the above embodiment, through the continuous peak judgment mechanism, accidental noise peaks and true synchronization peaks can be effectively distinguished, and the system can be prevented from entering synchronization prematurely due to a single pseudo-peak or misjudged peak, improving the judgment accuracy and reducing the synchronization failure rate; in addition, the introduction of the spacing tolerance and continuous counting mechanism allows a certain degree of synchronization deviation and improves the adaptability to channel disturbances.

[0161] Typically, frame synchronization is achieved by detecting the synchronization sequence and the flag sequence in the pre-embedded frame preamble. During the frame synchronization process, the receiving end not only needs to determine whether it enters the synchronization state, but also needs to accurately determine when the synchronization ends.

[0162] To this end, in some embodiments, in step 460, the steps of signal synchronization include steps 462 to 466: Step 462, receive the frame preamble; the frame preamble includes a synchronization sequence and a flag sequence; Step 464, whenever a valid correlation peak is determined based on the received synchronization sequence, perform signal transformation processing on the received synchronization sequence to obtain a signal transformation result; the signal transformation result is used for channel estimation; Step 466, when it is determined that the flag sequence is received, end the signal synchronization.

[0163] In this embodiment, when the signal receiving device detects multiple consecutive valid correlation peaks, it is determined to enter the synchronization state. The signal receiving device receives and buffers the frame preamble, and the frame preamble is composed of one or more synchronization sequences SYNCP and a flag sequence SYNCM.

[0164] Each time a new valid correlation peak is detected, the signal receiving device performs signal transformation processing on the synchronization sequence at its corresponding position, such as the Fast Fourier Transform (FFT), to obtain a frequency-domain transformation result, which is used to construct a channel estimation value. To suppress instantaneous fluctuations, multiple FFT results can be averaged.

[0165] When the signal receiving device detects the flag sequence SYNCM (such as the autocorrelation result is a negative peak, or the matching flag bit pattern), it is confirmed that the frame preamble ends, and the frame synchronization process is completed accordingly.

[0166] In the above embodiment, the signal receiving device executes the signal synchronization process, and the transformation processing is triggered by the synchronization sequence, and the flag sequence confirms the exit from the synchronization process. Thus, a stable and reliable synchronization start and exit mechanism can be realized, and at the same time, high-quality input is provided for channel estimation.

[0167] The frame structure is often designed so that there are obvious characteristic differences between the flag sequence and the synchronization sequence, such as polarity inversion. By analyzing whether the autocorrelation result changes from a positive peak to a negative value, it can be determined whether SYNCM has been received, so that the synchronization process can be reliably terminated without performing a complete pattern match on SYNCM.

[0168] For this purpose, in some embodiments, before step 466, it further includes step 465: when determining that the autocorrelation value is negative based on the autocorrelation result corresponding to any valid correlation peak, determining that the flag sequence is received; wherein, the boundary position between the synchronization sequence and the flag sequence is the end position of signal synchronization.

[0169] In this embodiment, the signal receiving device obtains the autocorrelation result corresponding to the currently detected valid correlation peak. If the autocorrelation result is negative, it is determined that the currently input signal already contains the flag sequence SYNCM, that is, the preamble part of the frame ends. Further, this location is used as the boundary point between the synchronization sequence SYNCP and the flag sequence SYNCM, and is determined as the end position of frame synchronization.

[0170] In the above embodiment, by analyzing the sign change of the autocorrelation result, there is no need to specifically mark the frame tail structure, and the closed-loop control of the synchronization process is achieved. Compared with matching the flag sequence or performing continuous cross-correlation operations, judging the sign of the autocorrelation value is more efficient and has stronger real-time performance.

[0171] Combined with one or more of the above embodiments, a specific embodiment will be described below.

[0172] Figure 7 It is a schematic flowchart of the power line carrier signal synchronization method provided by the present invention in some other embodiments. As Figure 7 shown, in some embodiments, the power line carrier signal synchronization method provided by the present invention includes the following steps: Step a, signal detection stage: Monitor the power line channel and determine whether a signal sequence is detected.

[0173] The signal receiving device monitors the power line channel and determines whether a signal sequence containing synchronization information is detected. For example, the signal receiving device can continuously monitor the signal amplitude or power level in the power line channel and compare it with a preset noise threshold to determine whether a possible signal sequence is detected.

[0174] Step b, autocorrelation result calculation stage: When a signal sequence is received, determine the autocorrelation result based on the known signal sequence.

[0175] Upon receiving a signal sequence, a signal receiving device determines symbol coefficients corresponding to each sampling point based on the signal amplitudes corresponding to the respective sampling points in the signal sequence; wherein, the signs of the signal amplitudes are the same as the signs of the symbol coefficients; based on the symbol coefficients corresponding to each sampling point, a symbol sequence corresponding to the signal sequence is determined; for any sampling point, the symbol coefficient corresponding to the targeted sampling point is multiplied by the known signal at the same position in the known signal sequence to obtain a cross-correlation value corresponding to the targeted sampling point; based on the sum of the cross-correlation values corresponding to each sampling point in the signal sequence, a cross-correlation result is obtained. Moreover, the signal receiving device determines a target historical cross-correlation result, and multiplies the cross-correlation result by the target historical cross-correlation result to obtain an autocorrelation value; based on the absolute value of the autocorrelation value, an autocorrelation result is obtained.

[0176] Exemplarily, the signal receiving device uses a sliding window of length 1024 to frame the received signal data, and performs symbol cross-correlation between the signal within the sliding window and the local SYNCP sequence, that is, only the symbol coefficients are taken, and no specific amplitude multiplication operation is required, so as to reduce the consumption of computing resources and improve the computing efficiency.

[0177] After calculating the cross-correlation result, the signal receiving device stores the cross-correlation result in a buffer. Each time a new cross-correlation value is obtained, it performs autocorrelation with the cross-correlation value before its 1024th point to obtain an autocorrelation result AutoCorrVal, and takes the absolute value AbsAutoCorr.

[0178] Thus, autocorrelation is performed on the basis of the cross-correlation value, that is, by accumulating two cross-correlation values at a preset interval, so that a more obvious correlation peak can be obtained.

[0179] Step c: Initialize the dynamic threshold.

[0180] In each process of finding the maximum correlation peak, the signal receiving device first initializes the dynamic threshold, that is, determines the dynamic threshold as a preset value.

[0181] Step d: Dynamic threshold update mechanism and effective correlation peak detection stage.

[0182] The signal receiving device compares the obtained autocorrelation result with the dynamic threshold; in the case where the autocorrelation result exceeds the dynamic threshold, the dynamic threshold is updated based on the current autocorrelation result to obtain a new dynamic threshold; the new dynamic threshold is used to compare with the newly obtained autocorrelation result next time; continue to receive the signal sequence, and return to the first step to continue execution until the dynamic threshold remains stable, and the dynamic threshold is obtained.

[0183] When the absolute value of autocorrelation AbsAutoCorr is greater than the set dynamic threshold, it indicates that the detected data has a large correlation with the local sequence. However, since there is an ascending process for the correlation peak, it is necessary to continue to find the position with the largest correlation peak. Therefore, each time the signal receiving device obtains a larger AbsAutoCorr, it updates the dynamic threshold with this value and continues to search backward until it no longer increases. The dynamic threshold obtained from the last update is used as the target dynamic threshold, and the target sampling points and autocorrelation results of a preset number after the current sampling point are determined. When the autocorrelation results corresponding to each of the target sampling points do not exceed the autocorrelation result corresponding to the current sampling point, it is determined that the target dynamic threshold is valid, and then the current autocorrelation result is determined as the maximum correlation peak. Thus, the signal receiving device records this position and the current absolute value of autocorrelation to record the maximum correlation peak.

[0184] After that, the signal receiving device verifies the validity of the maximum correlation peak. The signal receiving device determines the sampling point interval associated with the maximum correlation peak; the sampling point interval does not include the sampling point corresponding to the peak value of the maximum correlation peak, and based on the autocorrelation results corresponding to each sampling point within the sampling point interval, the average autocorrelation result is determined. Furthermore, the signal receiving device determines the signal-to-noise ratio of the peak value of the maximum correlation peak to the average autocorrelation result; when the signal-to-noise ratio exceeds the signal-to-noise ratio threshold, it is determined that the maximum correlation peak is valid.

[0185] Exemplarily, after the signal receiving device finds the position with the largest correlation peak, it skips 20 points backward, then calculates the average value of the absolute values of autocorrelation for 1000 points as the background noise, and calculates the ratio of the autocorrelation value of the maximum peak to the average value of the absolute values of autocorrelation for this segment, which is the signal-to-noise ratio. If the signal-to-noise ratio is greater than the set signal-to-noise ratio threshold, it is considered that this correlation peak is valid, and the adjacent count value Begincount = 1.

[0186] Step e: Continuous correlation peak judgment stage.

[0187] The signal receiving device determines the historical valid correlation peaks and determines the first spacing between the historical valid correlation peaks and the current valid correlation peak; when the first spacing meets the spacing threshold condition, the adjacent count value is incremented; when the first spacing does not meet the spacing threshold condition, the adjacent count value is reset; when the adjacent count value exceeds the preset count threshold, it is determined that the valid correlation peak and the historical valid correlation peak form a continuous correlation peak. When the adjacent count value exceeds the preset count threshold, it indicates that the number of continuous correlation peaks exceeds the preset threshold, and then the signal receiving device confirms that the signal synchronization timing has been met.

[0188] For example, the signal receiving device repeats steps a to e, finds the next correlation peak, and determines whether the distance between the correlation peak position and the previous correlation peak is within the range of 1024 ± 20. If it is within the range, it indicates that continuous correlation peaks are found, and Begincount++. If it is not within the range, it indicates that SYNCP is missed in the middle, and Begincount is reset to 1.

[0189] Step f: Signal synchronization and channel estimation stage: When the valid correlation peaks and the historical valid correlation peaks form continuous correlation peaks, signal synchronization is started.

[0190] When the valid correlation peaks and the historical valid correlation peaks form continuous correlation peaks, the signal receiving device receives the frame preamble signal; the frame preamble signal includes a synchronization sequence and a flag sequence. Whenever a valid correlation peak is determined based on the received synchronization sequence, the signal receiving device performs signal transformation processing on the received synchronization sequence to obtain a signal transformation result; the signal transformation result is used for channel estimation.

[0191] Exemplarily, when Begincount > 2, it indicates that three consecutive valid correlation peaks are found. The signal receiving device enters the SYNCBegin state and continues to search for correlation peaks backward. Whenever a correlation peak is found, the signal receiving device performs FFT on the signal at the corresponding position of the input signal, takes the average with the previous FFT result, and saves the FFT result for subsequent channel estimation.

[0192] Step g: Flag sequence detection stage: When, based on the autocorrelation result corresponding to any valid correlation peak, it is determined that the autocorrelation value is negative, the signal receiving device determines that the flag sequence is received; among them, the boundary position between the synchronization sequence and the flag sequence is the end position of signal synchronization.

[0193] Exemplarily, when the signal receiving device finds a certain correlation peak and the autocorrelation result AutoCorrVal is negative, it indicates that the position of SYNCM is found. Then the signal receiving device no longer performs FFT operations, and takes the position at the junction of SYNCP and SYNCM as the position of the final frame synchronization positioning, which is used to obtain frame control data and data payload subsequently.

[0194] When the flag sequence is successfully detected, the signal receiving device ends the signal synchronization process, completes the synchronization positioning of the frame structure, and provides data support for subsequent data parsing.

[0195] To verify the robustness and detection accuracy of the power line carrier signal synchronization method proposed in the present invention under different channel conditions, relevant simulation experiments were carried out. Specifically, under the conditions of noiseless and a low signal-to-noise ratio of -10 dB, the cross-correlation processing results between the input signal and the known synchronization sequence, as well as the autocorrelation processing results further calculated, were analyzed and compared.

[0196] The following will be shown respectively in combination with the simulation data diagrams.

[0197] Figure 8 It is a schematic diagram of the cross-correlation result obtained by performing cross-correlation operation on the signal sequence and the known synchronization sequence under noiseless conditions provided in some embodiments of the present invention. Figure 8 It shows the cross-correlation result diagram obtained by performing cross-correlation operation on the signal sequence and the known synchronization sequence under noiseless conditions. As Figure 8 shown, in an ideal channel environment (i.e., noiseless condition), after the received signal sequence is cross-correlated with the local known synchronization sequence SYNCP, the obtained cross-correlation result CorrVal presents a significant sharp peak, which can clearly locate the synchronization point position. This correlation peak has a very high amplitude advantage relative to the surrounding background noise, indicating that under the condition of no interference, the traditional cross-correlation method can achieve a relatively ideal synchronization detection effect.

[0198] Figure 9 It is a schematic diagram of the autocorrelation result obtained by performing autocorrelation operation based on the cross-correlation result under noiseless conditions provided in some embodiments of the present invention. Figure 9 It shows the autocorrelation result diagram obtained by further performing autocorrelation processing on this basis. As Figure 9 shown, after the maximum correlation peak is subjected to autocorrelation operation, the autocorrelation value autoCorr still maintains a highly concentrated and clear sharp shape, and its corresponding absolute value is much higher than the rest of the background part, which can further enhance the ability to confirm the position of the correlation peak. Thus, it can be seen that under noiseless conditions, introducing autocorrelation calculation can enhance the correlation peak characteristics, improve the synchronization positioning accuracy, and provide a more reliable data basis for subsequent synchronization confirmation and dynamic threshold setting.

[0199] Figure 10 It is a schematic diagram of the cross-correlation result obtained by performing cross-correlation operation on the signal sequence and the known synchronization sequence under the condition of noise interference provided in some embodiments of the present invention. Figure 10 It shows the cross-correlation result diagram obtained under the condition of high noise interference in the channel. As Figure 10As shown, under the condition of a power line channel with a relatively low signal-to-noise ratio (SNR = -10 dB) and the presence of burst interference, although the main correlation peak in the cross-correlation result CorrVal still exists, its relative amplitude significantly decreases, and the distinguishability from multiple surrounding false peaks weakens. In addition, background noise causes obvious perturbations in the overall cross-correlation graph, easily leading to the problem of misjudging the synchronization position. This verifies the defect of the traditional cross-correlation-based synchronization detection method in terms of insufficient robustness under low signal-to-noise ratio conditions.

[0200] Figure 11 It is a schematic diagram of the autocorrelation result obtained after performing autocorrelation operation based on the cross-correlation result in some embodiments of the present invention under the condition of noise interference. Figure 11 It shows the autocorrelation result graph obtained after performing autocorrelation processing based on the cross-correlation result under the condition of high noise interference in the channel. As Figure 11 shown, under the same low signal-to-noise ratio condition (SNR = -10 dB), after performing autocorrelation processing based on the cross-correlation result, the obtained autocorrelation value autoCorr significantly improves the relative prominence of the main correlation peak. Although channel interference still exists, the absolute value of the autocorrelation value shows higher concentration and discriminability at the main peak position. Compared with Figure 10 the mixed interference peaks, autocorrelation processing effectively suppresses the pseudo-peak interference and enhances the ability to identify the effective correlation peak. Combining the dynamic threshold update mechanism and the peak shape evaluation method can further improve the accuracy and robustness of synchronization recognition.

[0201] Through the above comparison, it can be more intuitively observed that the method proposed by the present invention can still effectively extract the correlation peak, adaptively adjust the dynamic threshold, and identify the synchronization starting point in the presence of channel noise, thereby achieving robust signal synchronization.

[0202] The power line carrier signal synchronization method provided by the embodiments of the present invention may be executed by a power line carrier signal synchronization device. In the embodiments of the present invention, taking the power line carrier signal synchronization device executing the power line carrier signal synchronization method as an example, the power line carrier signal synchronization device provided by the embodiments of the present invention is described.

[0203] Figure 12 It is a schematic structural diagram of the power line carrier signal synchronization device provided by the present invention in some embodiments. As Figure 12 shown, the embodiments of the present invention also provide a power line carrier signal synchronization device, which is applied to a signal receiving device. The power line carrier signal synchronization device includes an operation module 1201, a processing module 1202, and a synchronization module 1203. Among them: The operation module 1201 is configured to determine the autocorrelation result based on a known signal sequence when receiving a signal sequence.

[0204] A processing module 1202 is configured to determine a valid correlation peak when the autocorrelation result exceeds a dynamic threshold; the dynamic threshold is dynamically updated according to the variation trend of multiple autocorrelation results.

[0205] A synchronization module 1203 is configured to initiate signal synchronization when the valid correlation peak and the historical valid correlation peak form a continuous correlation peak.

[0206] According to the power line carrier signal synchronization device provided by an embodiment of the present invention, by detecting a signal sequence and, when receiving the signal sequence, determining an autocorrelation result based on a known signal sequence, the synchronization feature in the signal can be effectively detected through autocorrelation processing, improving the accuracy and reliability of synchronization detection; when the autocorrelation result exceeds the dynamic threshold, a valid correlation peak is determined, which can eliminate invalid correlation peaks, improving the anti-interference ability of synchronization detection, and adopting a dynamic threshold mechanism based on the variation trend of the autocorrelation result can adaptively update the threshold, making the identification of the valid correlation peak more accurate; and when the valid correlation peak and the historical valid correlation peak form a continuous correlation peak, by detecting the continuous correlation peaks, the stability and consistency of the synchronization signal are ensured, thereby reliably initiating the signal synchronization process, reducing the possibility of false judgment and missed judgment, achieving efficient and accurate synchronization of the signal in a complex channel environment, and enhancing the robustness and reliability of signal synchronization.

[0207] According to an embodiment of the present invention, the processing module is further configured to determine a maximum correlation peak when the autocorrelation result exceeds the dynamic threshold; the peak value of the maximum correlation peak is the current autocorrelation result, and the peak position is the signal position of the sampling point corresponding to the peak; verify the validity of the maximum correlation peak, and when the validity verification passes, determine the maximum correlation peak as a valid correlation peak.

[0208] According to an embodiment of the present invention, the processing module is further configured to determine a sampling point interval associated with the maximum correlation peak; the sampling point interval does not include the sampling point corresponding to the peak value of the maximum correlation peak; determine the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak.

[0209] According to an embodiment of the present invention, the processing module is further configured to determine an average autocorrelation result based on the autocorrelation results corresponding to each sampling point within the sampling point interval; determine the signal-to-noise ratio of the peak value of the maximum correlation peak to the average autocorrelation result; wherein, the signal-to-noise ratio characterizes the shape of the maximum correlation peak, and the larger the signal-to-noise ratio, the sharper the maximum correlation peak; when the signal-to-noise ratio exceeds the signal-to-noise ratio threshold, determine that the maximum correlation peak is valid.

[0210] According to an embodiment of the present invention, the above-mentioned device further includes a threshold module, which is used to compare the current autocorrelation result with a dynamic threshold; in the case that the autocorrelation result exceeds the dynamic threshold, update the dynamic threshold based on the current autocorrelation result to obtain a new dynamic threshold; the new dynamic threshold is used to compare with the newly obtained autocorrelation result next time; continue to receive the signal sequence, and return to the step of comparing the current autocorrelation result with the dynamic threshold to continue execution until the current autocorrelation result does not exceed the dynamic threshold obtained by the most recent update, to obtain a target dynamic threshold; verify the effectiveness of the target dynamic threshold, and in the case that the target dynamic threshold is effective, determine the current autocorrelation result as the maximum correlation peak.

[0211] According to an embodiment of the present invention, the threshold module is further used to determine a preset number of target sampling points after the current sampling point, and respectively determine the autocorrelation results corresponding to each target sampling point; the current sampling point corresponds to the current autocorrelation result; in the case that the autocorrelation results corresponding to each target sampling point do not exceed the autocorrelation result corresponding to the current sampling point, determine that the target dynamic threshold is effective.

[0212] According to an embodiment of the present invention, the above-mentioned device further includes a judgment module, which is used to determine the historical valid correlation peak and determine the first distance between the historical valid correlation peak and the current valid correlation peak; in the case that the first distance meets the distance threshold condition, increase the adjacent count value; in the case that the first distance does not meet the distance threshold condition, reset the adjacent count value; in the case that the adjacent count value exceeds the preset count threshold, determine that the valid correlation peak and the historical valid correlation peak form a continuous correlation peak.

[0213] According to an embodiment of the present invention, the operation module is further used to perform cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result; determine the target historical cross-correlation result; perform autocorrelation operation on the cross-correlation result and the target historical cross-correlation result to obtain an autocorrelation result.

[0214] According to an embodiment of the present invention, the operation module is further used to determine the symbol coefficient corresponding to each sampling point based on the signal amplitude corresponding to each sampling point in the signal sequence; wherein, the positive and negative of the signal amplitude are consistent with the positive and negative of the symbol coefficient; based on the symbol coefficients corresponding to each sampling point, determine the symbol sequence corresponding to the signal sequence; perform cross-correlation operation on the symbol sequence and the known signal sequence to obtain a cross-correlation result.

[0215] According to an embodiment of the present invention, the operation module is further used to multiply the symbol coefficient corresponding to the sampling point targeted by any sampling point by the known signal at the same position in the known signal sequence to obtain the cross-correlation value corresponding to the sampling point targeted; based on the sum of the cross-correlation values corresponding to each sampling point in the signal sequence, obtain a cross-correlation result.

[0216] According to an embodiment of the present invention, the operation module is further configured to multiply the cross-correlation result by the target historical cross-correlation result to obtain an autocorrelation value; and obtain an autocorrelation result based on the absolute value of the autocorrelation value.

[0217] According to an embodiment of the present invention, there is a second spacing between the target historical cross-correlation result and the cross-correlation result, and the length of the second spacing is the same as the length of the known signal sequence.

[0218] According to an embodiment of the present invention, the synchronization module is further configured to receive a frame preamble signal; the frame preamble signal includes a synchronization sequence and a flag sequence; whenever a valid correlation peak is determined based on the received synchronization sequence, perform signal transformation processing on the received synchronization sequence to obtain a signal transformation result; the signal transformation result is used for channel estimation; and end signal synchronization when it is determined that the flag sequence is received.

[0219] According to an embodiment of the present invention, the synchronization module is further configured to determine that the flag sequence is received when it is determined based on the autocorrelation result corresponding to any valid correlation peak that the autocorrelation value is negative; wherein the junction position between the synchronization sequence and the flag sequence is the end position of signal synchronization.

[0220] According to an embodiment of the present invention, the sequence length of the signal sequence is the same as the sequence length of the known signal sequence, and the known signal sequence corresponds to the synchronization sequence.

[0221] The power line carrier signal synchronization device in the embodiments of the present invention is applied to a signal receiving device, and the signal receiving device may be a computer device or a component in a computer device, such as an integrated circuit or a chip. The computer device may be a terminal device, etc. Exemplarily, the computer device may be a mobile phone, a tablet computer, a notebook computer, a palm computer, an in-vehicle computer device, a Mobile Internet Device (MID), an Augmented Reality (AR) / Virtual Reality (VR) device, a robot, a wearable device, an Ultra-mobile Personal Computer (UMPC), a netbook, or a Personal Digital Assistant (PDA), etc., and may 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 embodiments of the present invention do not make specific limitations.

[0222] The power line carrier signal synchronization device in the embodiments of the present invention can be a device with an operating system. The operating system can be the Microsoft (Windows) operating system, the Android operating system, the IOS operating system, or other possible operating systems, which are not specifically limited in the embodiments of the present invention.

[0223] The power line carrier signal synchronization device provided in the embodiments of the present invention can implement each process implemented by the method embodiments. To avoid repetition, it will not be elaborated here.

[0224] Figure 13 It is a schematic structural diagram of a computer device provided in some embodiments of the present invention. In some embodiments, as Figure 13 shown, the embodiments of the present invention also provide a computer device 1300, including a processor 1301, a memory 1302, and a computer program stored on the memory 1302 and executable on the processor 1301. When the program is executed by the processor 1301, it implements each process of the above method embodiments and can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0225] It should be noted that the computer devices in the embodiments of the present invention include the above-mentioned mobile computer devices and non-mobile computer devices.

[0226] The embodiments of the present invention also provide a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements each process of the above method embodiments of power line carrier signal synchronization and can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0227] Among them, the processor is the processor in the computer device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory ROM, random access memory RAM, magnetic disks, or optical discs.

[0228] The embodiments of the present invention also provide a computer program product, including a computer program, which implements the above power line carrier signal synchronization method when executed by a processor.

[0229] Among them, the processor is the processor in the computer device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory ROM, random access memory RAM, magnetic disks, or optical discs.

[0230] Another embodiment of the present invention provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is configured to run programs or instructions to implement each process of the above embodiment of the power line carrier signal synchronization method and can achieve the same technical effects. To avoid repetition, details are not described herein again.

[0231] It should be understood that the chip mentioned in the embodiment of the present invention may also be referred to as a system-on-chip, system chip, chip system, or system-on-chip.

[0232] It should be noted that in this article, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the presence of additional identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the methods and devices in the embodiments of the present invention are not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in a reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0233] Through the description of the above embodiments, those skilled in the art can clearly understand that the above embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the related technology, can be embodied in the form of a computer software product. The computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disc) and includes several instructions for causing a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in various embodiments of the present invention.

[0234] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the present invention and the claims, and all of them belong to the protection scope of the present invention.

[0235] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0236] If there is no special instruction, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution.

[0237] If there is no special instruction, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0238] If there is no special instruction, all steps of the present invention can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0239] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A power line carrier signal synchronization method, characterized in that The method includes: When receiving a signal sequence, determining an autocorrelation result based on a known signal sequence; When the autocorrelation result exceeds a dynamic threshold, determining a valid correlation peak; the dynamic threshold is dynamically updated according to the changing trend of multiple autocorrelation results; When the valid correlation peak and a historical valid correlation peak form a continuous correlation peak, starting signal synchronization.

2. The power line carrier signal synchronization method according to claim 1, wherein The step of determining a valid correlation peak when the autocorrelation result exceeds a dynamic threshold includes: When the autocorrelation result exceeds a dynamic threshold, determining a maximum correlation peak; the peak value of the maximum correlation peak is the current autocorrelation result, and the peak position is the signal position of the sampling point corresponding to the peak; Verifying the validity of the maximum correlation peak, and when the validity verification passes, determining the maximum correlation peak as a valid correlation peak.

3. The power line carrier signal synchronization method according to claim 2, wherein The step of verifying the validity of the maximum correlation peak includes: Determining a sampling point interval associated with the maximum correlation peak; the sampling point corresponding to the peak value of the maximum correlation peak is not included in the sampling point interval; Determining the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak.

4. The power line carrier signal synchronization method according to claim 3, wherein The step of determining the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak includes: Based on the autocorrelation results corresponding to each sampling point within the sampling point interval, determining an average autocorrelation result; Determining the signal-to-noise ratio between the peak value of the maximum correlation peak and the average autocorrelation result; wherein, the signal-to-noise ratio characterizes the shape of the maximum correlation peak, and the larger the signal-to-noise ratio, the sharper the maximum correlation peak; When the signal-to-noise ratio exceeds a signal-to-noise ratio threshold, determining that the maximum correlation peak is valid.

5. The power line carrier signal synchronization method according to any one of claims 1 to 4, characterized in that The step of determining a maximum correlation peak when the autocorrelation result exceeds a dynamic threshold includes: Comparing the current autocorrelation result with the dynamic threshold; When the autocorrelation result exceeds the dynamic threshold, updating the dynamic threshold based on the current autocorrelation result to obtain a new dynamic threshold; the new dynamic threshold is used for the next comparison with a newly obtained autocorrelation result; Continuing to receive the signal sequence, and returning to the step of comparing the current autocorrelation result with the dynamic threshold to continue execution until the current autocorrelation result does not exceed the dynamically threshold obtained by the most recent update, obtaining a target dynamic threshold; Verifying the validity of the target dynamic threshold, and when the target dynamic threshold is valid, determining the current autocorrelation result as the maximum correlation peak.

6. The power line carrier signal synchronization method according to claim 5, characterized in that, The step of verifying the validity of the target dynamic threshold includes: Determining a preset number of target sampling points after the current sampling point, and respectively determining the autocorrelation results corresponding to each target sampling point; the current sampling point corresponds to the current autocorrelation result; When the autocorrelation results corresponding to each target sampling point do not exceed the autocorrelation result corresponding to the current sampling point, determining that the target dynamic threshold is valid.

7. The power line carrier signal synchronization method according to claim 1, characterized in that, After determining the valid correlation peak, before starting signal synchronization when the valid correlation peak and a historical valid correlation peak form a continuous correlation peak, the method further includes: Determining a historical valid correlation peak, and determining a first distance between the historical valid correlation peak and the current valid correlation peak; When the first spacing meets the spacing threshold condition, increase the adjacent count value; When the first spacing does not meet the spacing threshold condition, reset the adjacent count value; When the adjacent count value exceeds the preset count threshold, determine that the valid correlation peak and the historical valid correlation peak form a continuous correlation peak.

8. The power line carrier signal synchronization method according to claim 1, wherein The determining the autocorrelation result based on the known signal sequence when receiving the signal sequence includes: Performing a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result; Determining the target historical cross-correlation result; Performing an autocorrelation operation on the cross-correlation result and the target historical cross-correlation result to obtain an autocorrelation result.

9. The power line carrier signal synchronization method according to claim 8, wherein The performing a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result includes: Based on the signal amplitudes corresponding to the respective sampling points in the signal sequence, determining the sign coefficients corresponding to the respective sampling points; wherein, the positive and negative of the signal amplitude are the same as the positive and negative of the sign coefficient; Based on the sign coefficients corresponding to the respective sampling points, determining the sign sequence corresponding to the signal sequence; Performing a cross-correlation operation on the sign sequence and the known signal sequence to obtain a cross-correlation result.

10. A power line carrier signal synchronization device, characterized in that, The device includes: An operation module, configured to determine an autocorrelation result based on a known signal sequence when receiving a signal sequence; A processing module, configured to determine a valid correlation peak when the autocorrelation result exceeds a dynamic threshold; the dynamic threshold is dynamically updated according to the change trend of multiple autocorrelation results; A synchronization module, configured to start signal synchronization when the valid correlation peak and the historical valid correlation peak form a continuous correlation peak.

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